Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 4424 insertions, 0 deletions

diff --git a/js/src/jit/BaselineCacheIRCompiler.cpp b/js/src/jit/BaselineCacheIRCompiler.cpp
new file mode 100644
index 0000000000..171771ed51
--- /dev/null
+++ b/js/src/jit/BaselineCacheIRCompiler.cpp
@@ -0,0 +1,4424 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jit/BaselineCacheIRCompiler.h"
+
+#include "gc/GC.h"
+#include "jit/CacheIR.h"
+#include "jit/CacheIRCloner.h"
+#include "jit/CacheIRWriter.h"
+#include "jit/JitFrames.h"
+#include "jit/JitRuntime.h"
+#include "jit/JitZone.h"
+#include "jit/Linker.h"
+#include "jit/MoveEmitter.h"
+#include "jit/RegExpStubConstants.h"
+#include "jit/SharedICHelpers.h"
+#include "jit/VMFunctions.h"
+#include "js/experimental/JitInfo.h"  // JSJitInfo
+#include "js/friend/DOMProxy.h"       // JS::ExpandoAndGeneration
+#include "proxy/DeadObjectProxy.h"
+#include "proxy/Proxy.h"
+#include "util/Unicode.h"
+#include "vm/StaticStrings.h"
+
+#include "jit/JitScript-inl.h"
+#include "jit/MacroAssembler-inl.h"
+#include "jit/SharedICHelpers-inl.h"
+#include "jit/VMFunctionList-inl.h"
+#include "vm/List-inl.h"
+
+using namespace js;
+using namespace js::jit;
+
+using mozilla::Maybe;
+
+using JS::ExpandoAndGeneration;
+
+namespace js {
+namespace jit {
+
+static uint32_t GetICStackValueOffset() {
+  uint32_t offset = ICStackValueOffset;
+  if (JitOptions.enableICFramePointers) {
+#ifdef JS_USE_LINK_REGISTER
+    // The frame pointer and return address are also on the stack.
+    offset += 2 * sizeof(uintptr_t);
+#else
+    // The frame pointer is also on the stack.
+    offset += sizeof(uintptr_t);
+#endif
+  }
+  return offset;
+}
+
+static void PushICFrameRegs(MacroAssembler& masm) {
+  MOZ_ASSERT(JitOptions.enableICFramePointers);
+#ifdef JS_USE_LINK_REGISTER
+  masm.pushReturnAddress();
+#endif
+  masm.push(FramePointer);
+}
+
+static void PopICFrameRegs(MacroAssembler& masm) {
+  MOZ_ASSERT(JitOptions.enableICFramePointers);
+  masm.pop(FramePointer);
+#ifdef JS_USE_LINK_REGISTER
+  masm.popReturnAddress();
+#endif
+}
+
+Address CacheRegisterAllocator::addressOf(MacroAssembler& masm,
+                                          BaselineFrameSlot slot) const {
+  uint32_t offset =
+      stackPushed_ + GetICStackValueOffset() + slot.slot() * sizeof(JS::Value);
+  return Address(masm.getStackPointer(), offset);
+}
+BaseValueIndex CacheRegisterAllocator::addressOf(MacroAssembler& masm,
+                                                 Register argcReg,
+                                                 BaselineFrameSlot slot) const {
+  uint32_t offset =
+      stackPushed_ + GetICStackValueOffset() + slot.slot() * sizeof(JS::Value);
+  return BaseValueIndex(masm.getStackPointer(), argcReg, offset);
+}
+
+// BaselineCacheIRCompiler compiles CacheIR to BaselineIC native code.
+BaselineCacheIRCompiler::BaselineCacheIRCompiler(JSContext* cx,
+                                                 TempAllocator& alloc,
+                                                 const CacheIRWriter& writer,
+                                                 uint32_t stubDataOffset)
+    : CacheIRCompiler(cx, alloc, writer, stubDataOffset, Mode::Baseline,
+                      StubFieldPolicy::Address),
+      makesGCCalls_(false) {}
+
+// AutoStubFrame methods
+AutoStubFrame::AutoStubFrame(BaselineCacheIRCompiler& compiler)
+    : compiler(compiler)
+#ifdef DEBUG
+      ,
+      framePushedAtEnterStubFrame_(0)
+#endif
+{
+}
+void AutoStubFrame::enter(MacroAssembler& masm, Register scratch) {
+  MOZ_ASSERT(compiler.allocator.stackPushed() == 0);
+
+  if (JitOptions.enableICFramePointers) {
+    // If we have already pushed the frame pointer, pop it
+    // before creating the stub frame.
+    PopICFrameRegs(masm);
+  }
+  EmitBaselineEnterStubFrame(masm, scratch);
+
+#ifdef DEBUG
+  framePushedAtEnterStubFrame_ = masm.framePushed();
+#endif
+
+  MOZ_ASSERT(!compiler.enteredStubFrame_);
+  compiler.enteredStubFrame_ = true;
+
+  // All current uses of this are to call VM functions that can GC.
+  compiler.makesGCCalls_ = true;
+}
+void AutoStubFrame::leave(MacroAssembler& masm) {
+  MOZ_ASSERT(compiler.enteredStubFrame_);
+  compiler.enteredStubFrame_ = false;
+
+#ifdef DEBUG
+  masm.setFramePushed(framePushedAtEnterStubFrame_);
+#endif
+
+  EmitBaselineLeaveStubFrame(masm);
+  if (JitOptions.enableICFramePointers) {
+    // We will pop the frame pointer when we return,
+    // so we have to push it again now.
+    PushICFrameRegs(masm);
+  }
+}
+
+void AutoStubFrame::storeTracedValue(MacroAssembler& masm, ValueOperand value) {
+  MOZ_ASSERT(compiler.localTracingSlots_ < 255);
+  MOZ_ASSERT(masm.framePushed() - framePushedAtEnterStubFrame_ ==
+             compiler.localTracingSlots_ * sizeof(Value));
+  masm.Push(value);
+  compiler.localTracingSlots_++;
+}
+
+void AutoStubFrame::loadTracedValue(MacroAssembler& masm, uint8_t slotIndex,
+                                    ValueOperand value) {
+  MOZ_ASSERT(slotIndex <= compiler.localTracingSlots_);
+  int32_t offset = BaselineStubFrameLayout::LocallyTracedValueOffset +
+                   slotIndex * sizeof(Value);
+  masm.loadValue(Address(FramePointer, -offset), value);
+}
+
+#ifdef DEBUG
+AutoStubFrame::~AutoStubFrame() { MOZ_ASSERT(!compiler.enteredStubFrame_); }
+#endif
+
+}  // namespace jit
+}  // namespace js
+
+bool BaselineCacheIRCompiler::makesGCCalls() const { return makesGCCalls_; }
+
+Address BaselineCacheIRCompiler::stubAddress(uint32_t offset) const {
+  return Address(ICStubReg, stubDataOffset_ + offset);
+}
+
+template <typename Fn, Fn fn>
+void BaselineCacheIRCompiler::callVM(MacroAssembler& masm) {
+  VMFunctionId id = VMFunctionToId<Fn, fn>::id;
+  callVMInternal(masm, id);
+}
+
+JitCode* BaselineCacheIRCompiler::compile() {
+  AutoCreatedBy acb(masm, "BaselineCacheIRCompiler::compile");
+
+#ifndef JS_USE_LINK_REGISTER
+  masm.adjustFrame(sizeof(intptr_t));
+#endif
+#ifdef JS_CODEGEN_ARM
+  AutoNonDefaultSecondScratchRegister andssr(masm, BaselineSecondScratchReg);
+#endif
+  if (JitOptions.enableICFramePointers) {
+    /* [SMDOC] Baseline IC Frame Pointers
+     *
+     *  In general, ICs don't have frame pointers until just before
+     *  doing a VM call, at which point we retroactively create a stub
+     *  frame. However, for the sake of external profilers, we
+     *  optionally support full-IC frame pointers in baseline ICs, with
+     *  the following approach:
+     *    1. We push a frame pointer when we enter an IC.
+     *    2. We pop the frame pointer when we return from an IC, or
+     *       when we jump to the next IC.
+     *    3. Entering a stub frame for a VM call already pushes a
+     *       frame pointer, so we pop our existing frame pointer
+     *       just before entering a stub frame and push it again
+     *       just after leaving a stub frame.
+     *  Some ops take advantage of the fact that the frame pointer is
+     *  not updated until we enter a stub frame to read values from
+     *  the caller's frame. To support this, we allocate a separate
+     *  baselineFrame register when IC frame pointers are enabled.
+     */
+    PushICFrameRegs(masm);
+    masm.moveStackPtrTo(FramePointer);
+
+    MOZ_ASSERT(baselineFrameReg() != FramePointer);
+    masm.loadPtr(Address(FramePointer, 0), baselineFrameReg());
+  }
+
+  // Count stub entries: We count entries rather than successes as it much
+  // easier to ensure ICStubReg is valid at entry than at exit.
+  Address enteredCount(ICStubReg, ICCacheIRStub::offsetOfEnteredCount());
+  masm.add32(Imm32(1), enteredCount);
+
+  CacheIRReader reader(writer_);
+  do {
+    CacheOp op = reader.readOp();
+    perfSpewer_.recordInstruction(masm, op);
+    switch (op) {
+#define DEFINE_OP(op, ...)                 \
+  case CacheOp::op:                        \
+    if (!emit##op(reader)) return nullptr; \
+    break;
+      CACHE_IR_OPS(DEFINE_OP)
+#undef DEFINE_OP
+
+      default:
+        MOZ_CRASH("Invalid op");
+    }
+    allocator.nextOp();
+  } while (reader.more());
+
+  MOZ_ASSERT(!enteredStubFrame_);
+  masm.assumeUnreachable("Should have returned from IC");
+
+  // Done emitting the main IC code. Now emit the failure paths.
+  for (size_t i = 0; i < failurePaths.length(); i++) {
+    if (!emitFailurePath(i)) {
+      return nullptr;
+    }
+    if (JitOptions.enableICFramePointers) {
+      PopICFrameRegs(masm);
+    }
+    EmitStubGuardFailure(masm);
+  }
+
+  Linker linker(masm);
+  Rooted<JitCode*> newStubCode(cx_, linker.newCode(cx_, CodeKind::Baseline));
+  if (!newStubCode) {
+    cx_->recoverFromOutOfMemory();
+    return nullptr;
+  }
+
+  newStubCode->setLocalTracingSlots(localTracingSlots_);
+
+  return newStubCode;
+}
+
+bool BaselineCacheIRCompiler::emitGuardShape(ObjOperandId objId,
+                                             uint32_t shapeOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Register obj = allocator.useRegister(masm, objId);
+  AutoScratchRegister scratch1(allocator, masm);
+
+  bool needSpectreMitigations = objectGuardNeedsSpectreMitigations(objId);
+
+  Maybe<AutoScratchRegister> maybeScratch2;
+  if (needSpectreMitigations) {
+    maybeScratch2.emplace(allocator, masm);
+  }
+
+  FailurePath* failure;
+  if (!addFailurePath(&failure)) {
+    return false;
+  }
+
+  Address addr(stubAddress(shapeOffset));
+  masm.loadPtr(addr, scratch1);
+  if (needSpectreMitigations) {
+    masm.branchTestObjShape(Assembler::NotEqual, obj, scratch1, *maybeScratch2,
+                            obj, failure->label());
+  } else {
+    masm.branchTestObjShapeNoSpectreMitigations(Assembler::NotEqual, obj,
+                                                scratch1, failure->label());
+  }
+
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitGuardProto(ObjOperandId objId,
+                                             uint32_t protoOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Register obj = allocator.useRegister(masm, objId);
+  AutoScratchRegister scratch(allocator, masm);
+
+  FailurePath* failure;
+  if (!addFailurePath(&failure)) {
+    return false;
+  }
+
+  Address addr(stubAddress(protoOffset));
+  masm.loadObjProto(obj, scratch);
+  masm.branchPtr(Assembler::NotEqual, addr, scratch, failure->label());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitGuardCompartment(ObjOperandId objId,
+                                                   uint32_t globalOffset,
+                                                   uint32_t compartmentOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Register obj = allocator.useRegister(masm, objId);
+  AutoScratchRegister scratch(allocator, masm);
+
+  FailurePath* failure;
+  if (!addFailurePath(&failure)) {
+    return false;
+  }
+
+  // Verify that the global wrapper is still valid, as
+  // it is pre-requisite for doing the compartment check.
+  Address globalWrapper(stubAddress(globalOffset));
+  masm.loadPtr(globalWrapper, scratch);
+  Address handlerAddr(scratch, ProxyObject::offsetOfHandler());
+  masm.branchPtr(Assembler::Equal, handlerAddr,
+                 ImmPtr(&DeadObjectProxy::singleton), failure->label());
+
+  Address addr(stubAddress(compartmentOffset));
+  masm.branchTestObjCompartment(Assembler::NotEqual, obj, addr, scratch,
+                                failure->label());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitGuardAnyClass(ObjOperandId objId,
+                                                uint32_t claspOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Register obj = allocator.useRegister(masm, objId);
+  AutoScratchRegister scratch(allocator, masm);
+
+  FailurePath* failure;
+  if (!addFailurePath(&failure)) {
+    return false;
+  }
+
+  Address testAddr(stubAddress(claspOffset));
+  if (objectGuardNeedsSpectreMitigations(objId)) {
+    masm.branchTestObjClass(Assembler::NotEqual, obj, testAddr, scratch, obj,
+                            failure->label());
+  } else {
+    masm.branchTestObjClassNoSpectreMitigations(
+        Assembler::NotEqual, obj, testAddr, scratch, failure->label());
+  }
+
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitGuardHasProxyHandler(ObjOperandId objId,
+                                                       uint32_t handlerOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Register obj = allocator.useRegister(masm, objId);
+  AutoScratchRegister scratch(allocator, masm);
+
+  FailurePath* failure;
+  if (!addFailurePath(&failure)) {
+    return false;
+  }
+
+  Address testAddr(stubAddress(handlerOffset));
+  masm.loadPtr(testAddr, scratch);
+
+  Address handlerAddr(obj, ProxyObject::offsetOfHandler());
+  masm.branchPtr(Assembler::NotEqual, handlerAddr, scratch, failure->label());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitGuardSpecificObject(ObjOperandId objId,
+                                                      uint32_t expectedOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Register obj = allocator.useRegister(masm, objId);
+
+  FailurePath* failure;
+  if (!addFailurePath(&failure)) {
+    return false;
+  }
+
+  Address addr(stubAddress(expectedOffset));
+  masm.branchPtr(Assembler::NotEqual, addr, obj, failure->label());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitGuardSpecificFunction(
+    ObjOperandId objId, uint32_t expectedOffset, uint32_t nargsAndFlagsOffset) {
+  return emitGuardSpecificObject(objId, expectedOffset);
+}
+
+bool BaselineCacheIRCompiler::emitGuardFunctionScript(
+    ObjOperandId funId, uint32_t expectedOffset, uint32_t nargsAndFlagsOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  Register fun = allocator.useRegister(masm, funId);
+  AutoScratchRegister scratch(allocator, masm);
+
+  FailurePath* failure;
+  if (!addFailurePath(&failure)) {
+    return false;
+  }
+
+  Address addr(stubAddress(expectedOffset));
+  masm.loadPrivate(Address(fun, JSFunction::offsetOfJitInfoOrScript()),
+                   scratch);
+  masm.branchPtr(Assembler::NotEqual, addr, scratch, failure->label());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitGuardSpecificAtom(StringOperandId strId,
+                                                    uint32_t expectedOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Register str = allocator.useRegister(masm, strId);
+  AutoScratchRegister scratch(allocator, masm);
+
+  FailurePath* failure;
+  if (!addFailurePath(&failure)) {
+    return false;
+  }
+
+  Address atomAddr(stubAddress(expectedOffset));
+
+  Label done;
+  masm.branchPtr(Assembler::Equal, atomAddr, str, &done);
+
+  // The pointers are not equal, so if the input string is also an atom it
+  // must be a different string.
+  masm.branchTest32(Assembler::NonZero, Address(str, JSString::offsetOfFlags()),
+                    Imm32(JSString::ATOM_BIT), failure->label());
+
+  // Check the length.
+  masm.loadPtr(atomAddr, scratch);
+  masm.loadStringLength(scratch, scratch);
+  masm.branch32(Assembler::NotEqual, Address(str, JSString::offsetOfLength()),
+                scratch, failure->label());
+
+  // We have a non-atomized string with the same length. Call a helper
+  // function to do the comparison.
+  LiveRegisterSet volatileRegs(GeneralRegisterSet::Volatile(),
+                               liveVolatileFloatRegs());
+  masm.PushRegsInMask(volatileRegs);
+
+  using Fn = bool (*)(JSString* str1, JSString* str2);
+  masm.setupUnalignedABICall(scratch);
+  masm.loadPtr(atomAddr, scratch);
+  masm.passABIArg(scratch);
+  masm.passABIArg(str);
+  masm.callWithABI<Fn, EqualStringsHelperPure>();
+  masm.storeCallPointerResult(scratch);
+
+  LiveRegisterSet ignore;
+  ignore.add(scratch);
+  masm.PopRegsInMaskIgnore(volatileRegs, ignore);
+  masm.branchIfFalseBool(scratch, failure->label());
+
+  masm.bind(&done);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitGuardSpecificSymbol(SymbolOperandId symId,
+                                                      uint32_t expectedOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Register sym = allocator.useRegister(masm, symId);
+
+  FailurePath* failure;
+  if (!addFailurePath(&failure)) {
+    return false;
+  }
+
+  Address addr(stubAddress(expectedOffset));
+  masm.branchPtr(Assembler::NotEqual, addr, sym, failure->label());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitLoadValueResult(uint32_t valOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  AutoOutputRegister output(*this);
+  masm.loadValue(stubAddress(valOffset), output.valueReg());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitLoadFixedSlotResult(ObjOperandId objId,
+                                                      uint32_t offsetOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  AutoOutputRegister output(*this);
+  Register obj = allocator.useRegister(masm, objId);
+  AutoScratchRegisterMaybeOutput scratch(allocator, masm, output);
+
+  masm.load32(stubAddress(offsetOffset), scratch);
+  masm.loadValue(BaseIndex(obj, scratch, TimesOne), output.valueReg());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitLoadFixedSlotTypedResult(
+    ObjOperandId objId, uint32_t offsetOffset, ValueType) {
+  // The type is only used by Warp.
+  return emitLoadFixedSlotResult(objId, offsetOffset);
+}
+
+bool BaselineCacheIRCompiler::emitLoadDynamicSlotResult(ObjOperandId objId,
+                                                        uint32_t offsetOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  AutoOutputRegister output(*this);
+  Register obj = allocator.useRegister(masm, objId);
+  AutoScratchRegisterMaybeOutput scratch(allocator, masm, output);
+  AutoScratchRegister scratch2(allocator, masm);
+
+  masm.load32(stubAddress(offsetOffset), scratch);
+  masm.loadPtr(Address(obj, NativeObject::offsetOfSlots()), scratch2);
+  masm.loadValue(BaseIndex(scratch2, scratch, TimesOne), output.valueReg());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitCallScriptedGetterShared(
+    ValOperandId receiverId, uint32_t getterOffset, bool sameRealm,
+    uint32_t nargsAndFlagsOffset, Maybe<uint32_t> icScriptOffset) {
+  ValueOperand receiver = allocator.useValueRegister(masm, receiverId);
+  Address getterAddr(stubAddress(getterOffset));
+
+  AutoScratchRegister code(allocator, masm);
+  AutoScratchRegister callee(allocator, masm);
+  AutoScratchRegister scratch(allocator, masm);
+
+  bool isInlined = icScriptOffset.isSome();
+
+  // First, retrieve raw jitcode for getter.
+  masm.loadPtr(getterAddr, callee);
+  if (isInlined) {
+    FailurePath* failure;
+    if (!addFailurePath(&failure)) {
+      return false;
+    }
+    masm.loadBaselineJitCodeRaw(callee, code, failure->label());
+  } else {
+    masm.loadJitCodeRaw(callee, code);
+  }
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  if (!sameRealm) {
+    masm.switchToObjectRealm(callee, scratch);
+  }
+
+  // Align the stack such that the JitFrameLayout is aligned on
+  // JitStackAlignment.
+  masm.alignJitStackBasedOnNArgs(0, /*countIncludesThis = */ false);
+
+  // Getter is called with 0 arguments, just |receiver| as thisv.
+  // Note that we use Push, not push, so that callJit will align the stack
+  // properly on ARM.
+  masm.Push(receiver);
+
+  if (isInlined) {
+    // Store icScript in the context.
+    Address icScriptAddr(stubAddress(*icScriptOffset));
+    masm.loadPtr(icScriptAddr, scratch);
+    masm.storeICScriptInJSContext(scratch);
+  }
+
+  masm.Push(callee);
+  masm.PushFrameDescriptorForJitCall(FrameType::BaselineStub, /* argc = */ 0);
+
+  // Handle arguments underflow.
+  Label noUnderflow;
+  masm.loadFunctionArgCount(callee, callee);
+  masm.branch32(Assembler::Equal, callee, Imm32(0), &noUnderflow);
+
+  // Call the arguments rectifier.
+  ArgumentsRectifierKind kind = isInlined
+                                    ? ArgumentsRectifierKind::TrialInlining
+                                    : ArgumentsRectifierKind::Normal;
+  TrampolinePtr argumentsRectifier =
+      cx_->runtime()->jitRuntime()->getArgumentsRectifier(kind);
+  masm.movePtr(argumentsRectifier, code);
+
+  masm.bind(&noUnderflow);
+  masm.callJit(code);
+
+  stubFrame.leave(masm);
+
+  if (!sameRealm) {
+    masm.switchToBaselineFrameRealm(R1.scratchReg());
+  }
+
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitCallScriptedGetterResult(
+    ValOperandId receiverId, uint32_t getterOffset, bool sameRealm,
+    uint32_t nargsAndFlagsOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Maybe<uint32_t> icScriptOffset = mozilla::Nothing();
+  return emitCallScriptedGetterShared(receiverId, getterOffset, sameRealm,
+                                      nargsAndFlagsOffset, icScriptOffset);
+}
+
+bool BaselineCacheIRCompiler::emitCallInlinedGetterResult(
+    ValOperandId receiverId, uint32_t getterOffset, uint32_t icScriptOffset,
+    bool sameRealm, uint32_t nargsAndFlagsOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  return emitCallScriptedGetterShared(receiverId, getterOffset, sameRealm,
+                                      nargsAndFlagsOffset,
+                                      mozilla::Some(icScriptOffset));
+}
+
+bool BaselineCacheIRCompiler::emitCallNativeGetterResult(
+    ValOperandId receiverId, uint32_t getterOffset, bool sameRealm,
+    uint32_t nargsAndFlagsOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  ValueOperand receiver = allocator.useValueRegister(masm, receiverId);
+  Address getterAddr(stubAddress(getterOffset));
+
+  AutoScratchRegister scratch(allocator, masm);
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  // Load the callee in the scratch register.
+  masm.loadPtr(getterAddr, scratch);
+
+  masm.Push(receiver);
+  masm.Push(scratch);
+
+  using Fn =
+      bool (*)(JSContext*, HandleFunction, HandleValue, MutableHandleValue);
+  callVM<Fn, CallNativeGetter>(masm);
+
+  stubFrame.leave(masm);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitCallDOMGetterResult(ObjOperandId objId,
+                                                      uint32_t jitInfoOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  Register obj = allocator.useRegister(masm, objId);
+  Address jitInfoAddr(stubAddress(jitInfoOffset));
+
+  AutoScratchRegister scratch(allocator, masm);
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  // Load the JSJitInfo in the scratch register.
+  masm.loadPtr(jitInfoAddr, scratch);
+
+  masm.Push(obj);
+  masm.Push(scratch);
+
+  using Fn =
+      bool (*)(JSContext*, const JSJitInfo*, HandleObject, MutableHandleValue);
+  callVM<Fn, CallDOMGetter>(masm);
+
+  stubFrame.leave(masm);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitProxyGetResult(ObjOperandId objId,
+                                                 uint32_t idOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Register obj = allocator.useRegister(masm, objId);
+  Address idAddr(stubAddress(idOffset));
+
+  AutoScratchRegister scratch(allocator, masm);
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  // Load the jsid in the scratch register.
+  masm.loadPtr(idAddr, scratch);
+
+  masm.Push(scratch);
+  masm.Push(obj);
+
+  using Fn = bool (*)(JSContext*, HandleObject, HandleId, MutableHandleValue);
+  callVM<Fn, ProxyGetProperty>(masm);
+
+  stubFrame.leave(masm);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitFrameIsConstructingResult() {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  Register outputScratch = output.valueReg().scratchReg();
+
+  // Load the CalleeToken.
+  Address tokenAddr(baselineFrameReg(), JitFrameLayout::offsetOfCalleeToken());
+  masm.loadPtr(tokenAddr, outputScratch);
+
+  // The low bit indicates whether this call is constructing, just clear the
+  // other bits.
+  static_assert(CalleeToken_Function == 0x0);
+  static_assert(CalleeToken_FunctionConstructing == 0x1);
+  masm.andPtr(Imm32(0x1), outputScratch);
+
+  masm.tagValue(JSVAL_TYPE_BOOLEAN, outputScratch, output.valueReg());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitLoadConstantStringResult(uint32_t strOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  AutoOutputRegister output(*this);
+  AutoScratchRegisterMaybeOutput scratch(allocator, masm, output);
+
+  masm.loadPtr(stubAddress(strOffset), scratch);
+  masm.tagValue(JSVAL_TYPE_STRING, scratch, output.valueReg());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitCompareStringResult(JSOp op,
+                                                      StringOperandId lhsId,
+                                                      StringOperandId rhsId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  AutoOutputRegister output(*this);
+
+  Register left = allocator.useRegister(masm, lhsId);
+  Register right = allocator.useRegister(masm, rhsId);
+
+  AutoScratchRegisterMaybeOutput scratch(allocator, masm, output);
+
+  allocator.discardStack(masm);
+
+  Label slow, done;
+  masm.compareStrings(op, left, right, scratch, &slow);
+  masm.jump(&done);
+  masm.bind(&slow);
+  {
+    AutoStubFrame stubFrame(*this);
+    stubFrame.enter(masm, scratch);
+
+    // Push the operands in reverse order for JSOp::Le and JSOp::Gt:
+    // - |left <= right| is implemented as |right >= left|.
+    // - |left > right| is implemented as |right < left|.
+    if (op == JSOp::Le || op == JSOp::Gt) {
+      masm.Push(left);
+      masm.Push(right);
+    } else {
+      masm.Push(right);
+      masm.Push(left);
+    }
+
+    using Fn = bool (*)(JSContext*, HandleString, HandleString, bool*);
+    if (op == JSOp::Eq || op == JSOp::StrictEq) {
+      callVM<Fn, jit::StringsEqual<EqualityKind::Equal>>(masm);
+    } else if (op == JSOp::Ne || op == JSOp::StrictNe) {
+      callVM<Fn, jit::StringsEqual<EqualityKind::NotEqual>>(masm);
+    } else if (op == JSOp::Lt || op == JSOp::Gt) {
+      callVM<Fn, jit::StringsCompare<ComparisonKind::LessThan>>(masm);
+    } else {
+      MOZ_ASSERT(op == JSOp::Le || op == JSOp::Ge);
+      callVM<Fn, jit::StringsCompare<ComparisonKind::GreaterThanOrEqual>>(masm);
+    }
+
+    stubFrame.leave(masm);
+    masm.storeCallPointerResult(scratch);
+  }
+  masm.bind(&done);
+  masm.tagValue(JSVAL_TYPE_BOOLEAN, scratch, output.valueReg());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitSameValueResult(ValOperandId lhsId,
+                                                  ValOperandId rhsId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  AutoScratchRegister scratch(allocator, masm);
+  ValueOperand lhs = allocator.useValueRegister(masm, lhsId);
+#ifdef JS_CODEGEN_X86
+  // Use the output to avoid running out of registers.
+  allocator.copyToScratchValueRegister(masm, rhsId, output.valueReg());
+  ValueOperand rhs = output.valueReg();
+#else
+  ValueOperand rhs = allocator.useValueRegister(masm, rhsId);
+#endif
+
+  allocator.discardStack(masm);
+
+  Label done;
+  Label call;
+
+  // Check to see if the values have identical bits.
+  // This is correct for SameValue because SameValue(NaN,NaN) is true,
+  // and SameValue(0,-0) is false.
+  masm.branch64(Assembler::NotEqual, lhs.toRegister64(), rhs.toRegister64(),
+                &call);
+  masm.moveValue(BooleanValue(true), output.valueReg());
+  masm.jump(&done);
+
+  {
+    masm.bind(&call);
+
+    AutoStubFrame stubFrame(*this);
+    stubFrame.enter(masm, scratch);
+
+    masm.pushValue(lhs);
+    masm.pushValue(rhs);
+
+    using Fn = bool (*)(JSContext*, HandleValue, HandleValue, bool*);
+    callVM<Fn, SameValue>(masm);
+
+    stubFrame.leave(masm);
+    masm.tagValue(JSVAL_TYPE_BOOLEAN, ReturnReg, output.valueReg());
+  }
+
+  masm.bind(&done);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitStoreSlotShared(bool isFixed,
+                                                  ObjOperandId objId,
+                                                  uint32_t offsetOffset,
+                                                  ValOperandId rhsId) {
+  Register obj = allocator.useRegister(masm, objId);
+  ValueOperand val = allocator.useValueRegister(masm, rhsId);
+
+  AutoScratchRegister scratch1(allocator, masm);
+  Maybe<AutoScratchRegister> scratch2;
+  if (!isFixed) {
+    scratch2.emplace(allocator, masm);
+  }
+
+  Address offsetAddr = stubAddress(offsetOffset);
+  masm.load32(offsetAddr, scratch1);
+
+  if (isFixed) {
+    BaseIndex slot(obj, scratch1, TimesOne);
+    EmitPreBarrier(masm, slot, MIRType::Value);
+    masm.storeValue(val, slot);
+  } else {
+    masm.loadPtr(Address(obj, NativeObject::offsetOfSlots()), scratch2.ref());
+    BaseIndex slot(scratch2.ref(), scratch1, TimesOne);
+    EmitPreBarrier(masm, slot, MIRType::Value);
+    masm.storeValue(val, slot);
+  }
+
+  emitPostBarrierSlot(obj, val, scratch1);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitStoreFixedSlot(ObjOperandId objId,
+                                                 uint32_t offsetOffset,
+                                                 ValOperandId rhsId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  return emitStoreSlotShared(true, objId, offsetOffset, rhsId);
+}
+
+bool BaselineCacheIRCompiler::emitStoreDynamicSlot(ObjOperandId objId,
+                                                   uint32_t offsetOffset,
+                                                   ValOperandId rhsId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  return emitStoreSlotShared(false, objId, offsetOffset, rhsId);
+}
+
+bool BaselineCacheIRCompiler::emitAddAndStoreSlotShared(
+    CacheOp op, ObjOperandId objId, uint32_t offsetOffset, ValOperandId rhsId,
+    uint32_t newShapeOffset, Maybe<uint32_t> numNewSlotsOffset) {
+  Register obj = allocator.useRegister(masm, objId);
+  ValueOperand val = allocator.useValueRegister(masm, rhsId);
+
+  AutoScratchRegister scratch1(allocator, masm);
+  AutoScratchRegister scratch2(allocator, masm);
+
+  Address newShapeAddr = stubAddress(newShapeOffset);
+  Address offsetAddr = stubAddress(offsetOffset);
+
+  if (op == CacheOp::AllocateAndStoreDynamicSlot) {
+    // We have to (re)allocate dynamic slots. Do this first, as it's the
+    // only fallible operation here. Note that growSlotsPure is fallible but
+    // does not GC.
+    Address numNewSlotsAddr = stubAddress(*numNewSlotsOffset);
+
+    FailurePath* failure;
+    if (!addFailurePath(&failure)) {
+      return false;
+    }
+
+    LiveRegisterSet save(GeneralRegisterSet::Volatile(),
+                         liveVolatileFloatRegs());
+    masm.PushRegsInMask(save);
+
+    using Fn = bool (*)(JSContext* cx, NativeObject* obj, uint32_t newCount);
+    masm.setupUnalignedABICall(scratch1);
+    masm.loadJSContext(scratch1);
+    masm.passABIArg(scratch1);
+    masm.passABIArg(obj);
+    masm.load32(numNewSlotsAddr, scratch2);
+    masm.passABIArg(scratch2);
+    masm.callWithABI<Fn, NativeObject::growSlotsPure>();
+    masm.storeCallPointerResult(scratch1);
+
+    LiveRegisterSet ignore;
+    ignore.add(scratch1);
+    masm.PopRegsInMaskIgnore(save, ignore);
+
+    masm.branchIfFalseBool(scratch1, failure->label());
+  }
+
+  // Update the object's shape.
+  masm.loadPtr(newShapeAddr, scratch1);
+  masm.storeObjShape(scratch1, obj,
+                     [](MacroAssembler& masm, const Address& addr) {
+                       EmitPreBarrier(masm, addr, MIRType::Shape);
+                     });
+
+  // Perform the store. No pre-barrier required since this is a new
+  // initialization.
+  masm.load32(offsetAddr, scratch1);
+  if (op == CacheOp::AddAndStoreFixedSlot) {
+    BaseIndex slot(obj, scratch1, TimesOne);
+    masm.storeValue(val, slot);
+  } else {
+    MOZ_ASSERT(op == CacheOp::AddAndStoreDynamicSlot ||
+               op == CacheOp::AllocateAndStoreDynamicSlot);
+    masm.loadPtr(Address(obj, NativeObject::offsetOfSlots()), scratch2);
+    BaseIndex slot(scratch2, scratch1, TimesOne);
+    masm.storeValue(val, slot);
+  }
+
+  emitPostBarrierSlot(obj, val, scratch1);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitAddAndStoreFixedSlot(
+    ObjOperandId objId, uint32_t offsetOffset, ValOperandId rhsId,
+    uint32_t newShapeOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Maybe<uint32_t> numNewSlotsOffset = mozilla::Nothing();
+  return emitAddAndStoreSlotShared(CacheOp::AddAndStoreFixedSlot, objId,
+                                   offsetOffset, rhsId, newShapeOffset,
+                                   numNewSlotsOffset);
+}
+
+bool BaselineCacheIRCompiler::emitAddAndStoreDynamicSlot(
+    ObjOperandId objId, uint32_t offsetOffset, ValOperandId rhsId,
+    uint32_t newShapeOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Maybe<uint32_t> numNewSlotsOffset = mozilla::Nothing();
+  return emitAddAndStoreSlotShared(CacheOp::AddAndStoreDynamicSlot, objId,
+                                   offsetOffset, rhsId, newShapeOffset,
+                                   numNewSlotsOffset);
+}
+
+bool BaselineCacheIRCompiler::emitAllocateAndStoreDynamicSlot(
+    ObjOperandId objId, uint32_t offsetOffset, ValOperandId rhsId,
+    uint32_t newShapeOffset, uint32_t numNewSlotsOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  return emitAddAndStoreSlotShared(CacheOp::AllocateAndStoreDynamicSlot, objId,
+                                   offsetOffset, rhsId, newShapeOffset,
+                                   mozilla::Some(numNewSlotsOffset));
+}
+
+bool BaselineCacheIRCompiler::emitArrayJoinResult(ObjOperandId objId,
+                                                  StringOperandId sepId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  Register obj = allocator.useRegister(masm, objId);
+  Register sep = allocator.useRegister(masm, sepId);
+  AutoScratchRegisterMaybeOutput scratch(allocator, masm, output);
+
+  allocator.discardStack(masm);
+
+  // Load obj->elements in scratch.
+  masm.loadPtr(Address(obj, NativeObject::offsetOfElements()), scratch);
+  Address lengthAddr(scratch, ObjectElements::offsetOfLength());
+
+  // If array length is 0, return empty string.
+  Label finished;
+
+  {
+    Label arrayNotEmpty;
+    masm.branch32(Assembler::NotEqual, lengthAddr, Imm32(0), &arrayNotEmpty);
+    masm.movePtr(ImmGCPtr(cx_->names().empty_), scratch);
+    masm.tagValue(JSVAL_TYPE_STRING, scratch, output.valueReg());
+    masm.jump(&finished);
+    masm.bind(&arrayNotEmpty);
+  }
+
+  Label vmCall;
+
+  // Otherwise, handle array length 1 case.
+  masm.branch32(Assembler::NotEqual, lengthAddr, Imm32(1), &vmCall);
+
+  // But only if initializedLength is also 1.
+  Address initLength(scratch, ObjectElements::offsetOfInitializedLength());
+  masm.branch32(Assembler::NotEqual, initLength, Imm32(1), &vmCall);
+
+  // And only if elem0 is a string.
+  Address elementAddr(scratch, 0);
+  masm.branchTestString(Assembler::NotEqual, elementAddr, &vmCall);
+
+  // Store the value.
+  masm.loadValue(elementAddr, output.valueReg());
+  masm.jump(&finished);
+
+  // Otherwise call into the VM.
+  {
+    masm.bind(&vmCall);
+
+    AutoStubFrame stubFrame(*this);
+    stubFrame.enter(masm, scratch);
+
+    masm.Push(sep);
+    masm.Push(obj);
+
+    using Fn = JSString* (*)(JSContext*, HandleObject, HandleString);
+    callVM<Fn, jit::ArrayJoin>(masm);
+
+    stubFrame.leave(masm);
+
+    masm.tagValue(JSVAL_TYPE_STRING, ReturnReg, output.valueReg());
+  }
+
+  masm.bind(&finished);
+
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitPackedArraySliceResult(
+    uint32_t templateObjectOffset, ObjOperandId arrayId, Int32OperandId beginId,
+    Int32OperandId endId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  AutoScratchRegisterMaybeOutput scratch1(allocator, masm, output);
+  AutoScratchRegisterMaybeOutputType scratch2(allocator, masm, output);
+
+  Register array = allocator.useRegister(masm, arrayId);
+  Register begin = allocator.useRegister(masm, beginId);
+  Register end = allocator.useRegister(masm, endId);
+
+  FailurePath* failure;
+  if (!addFailurePath(&failure)) {
+    return false;
+  }
+
+  masm.branchArrayIsNotPacked(array, scratch1, scratch2, failure->label());
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch1);
+
+  // Don't attempt to pre-allocate the object, instead always use the slow
+  // path.
+  ImmPtr result(nullptr);
+
+  masm.Push(result);
+  masm.Push(end);
+  masm.Push(begin);
+  masm.Push(array);
+
+  using Fn =
+      JSObject* (*)(JSContext*, HandleObject, int32_t, int32_t, HandleObject);
+  callVM<Fn, ArraySliceDense>(masm);
+
+  stubFrame.leave(masm);
+
+  masm.tagValue(JSVAL_TYPE_OBJECT, ReturnReg, output.valueReg());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitArgumentsSliceResult(
+    uint32_t templateObjectOffset, ObjOperandId argsId, Int32OperandId beginId,
+    Int32OperandId endId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  AutoScratchRegisterMaybeOutput scratch(allocator, masm, output);
+
+  Register args = allocator.useRegister(masm, argsId);
+  Register begin = allocator.useRegister(masm, beginId);
+  Register end = allocator.useRegister(masm, endId);
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  // Don't attempt to pre-allocate the object, instead always use the slow path.
+  ImmPtr result(nullptr);
+
+  masm.Push(result);
+  masm.Push(end);
+  masm.Push(begin);
+  masm.Push(args);
+
+  using Fn =
+      JSObject* (*)(JSContext*, HandleObject, int32_t, int32_t, HandleObject);
+  callVM<Fn, ArgumentsSliceDense>(masm);
+
+  stubFrame.leave(masm);
+
+  masm.tagValue(JSVAL_TYPE_OBJECT, ReturnReg, output.valueReg());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitIsArrayResult(ValOperandId inputId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  AutoScratchRegister scratch1(allocator, masm);
+  AutoScratchRegisterMaybeOutput scratch2(allocator, masm, output);
+
+  ValueOperand val = allocator.useValueRegister(masm, inputId);
+
+  allocator.discardStack(masm);
+
+  Label isNotArray;
+  // Primitives are never Arrays.
+  masm.fallibleUnboxObject(val, scratch1, &isNotArray);
+
+  Label isArray;
+  masm.branchTestObjClass(Assembler::Equal, scratch1, &ArrayObject::class_,
+                          scratch2, scratch1, &isArray);
+
+  // isArray can also return true for Proxy wrapped Arrays.
+  masm.branchTestObjectIsProxy(false, scratch1, scratch2, &isNotArray);
+  Label done;
+  {
+    AutoStubFrame stubFrame(*this);
+    stubFrame.enter(masm, scratch2);
+
+    masm.Push(scratch1);
+
+    using Fn = bool (*)(JSContext*, HandleObject, bool*);
+    callVM<Fn, js::IsArrayFromJit>(masm);
+
+    stubFrame.leave(masm);
+
+    masm.tagValue(JSVAL_TYPE_BOOLEAN, ReturnReg, output.valueReg());
+    masm.jump(&done);
+  }
+
+  masm.bind(&isNotArray);
+  masm.moveValue(BooleanValue(false), output.valueReg());
+  masm.jump(&done);
+
+  masm.bind(&isArray);
+  masm.moveValue(BooleanValue(true), output.valueReg());
+
+  masm.bind(&done);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitIsTypedArrayResult(ObjOperandId objId,
+                                                     bool isPossiblyWrapped) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  AutoScratchRegisterMaybeOutput scratch(allocator, masm, output);
+  Register obj = allocator.useRegister(masm, objId);
+
+  allocator.discardStack(masm);
+
+  Label notTypedArray, isProxy, done;
+  masm.loadObjClassUnsafe(obj, scratch);
+  masm.branchIfClassIsNotTypedArray(scratch, &notTypedArray);
+  masm.moveValue(BooleanValue(true), output.valueReg());
+  masm.jump(&done);
+
+  masm.bind(&notTypedArray);
+  if (isPossiblyWrapped) {
+    masm.branchTestClassIsProxy(true, scratch, &isProxy);
+  }
+  masm.moveValue(BooleanValue(false), output.valueReg());
+
+  if (isPossiblyWrapped) {
+    masm.jump(&done);
+
+    masm.bind(&isProxy);
+
+    AutoStubFrame stubFrame(*this);
+    stubFrame.enter(masm, scratch);
+
+    masm.Push(obj);
+
+    using Fn = bool (*)(JSContext*, JSObject*, bool*);
+    callVM<Fn, jit::IsPossiblyWrappedTypedArray>(masm);
+
+    stubFrame.leave(masm);
+
+    masm.tagValue(JSVAL_TYPE_BOOLEAN, ReturnReg, output.valueReg());
+  }
+
+  masm.bind(&done);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitLoadStringCharResult(
+    StringOperandId strId, Int32OperandId indexId,
+    StringCharOutOfBounds outOfBounds) {
+  AutoOutputRegister output(*this);
+  Register str = allocator.useRegister(masm, strId);
+  Register index = allocator.useRegister(masm, indexId);
+  AutoScratchRegisterMaybeOutput scratch1(allocator, masm, output);
+  AutoScratchRegisterMaybeOutputType scratch2(allocator, masm, output);
+  AutoScratchRegister scratch3(allocator, masm);
+
+  // Bounds check, load string char.
+  Label done;
+  Label tagResult;
+  Label loadFailed;
+  if (outOfBounds == StringCharOutOfBounds::Failure) {
+    FailurePath* failure;
+    if (!addFailurePath(&failure)) {
+      return false;
+    }
+
+    masm.spectreBoundsCheck32(index, Address(str, JSString::offsetOfLength()),
+                              scratch3, failure->label());
+    masm.loadStringChar(str, index, scratch2, scratch1, scratch3,
+                        failure->label());
+
+    allocator.discardStack(masm);
+  } else {
+    // Discard the stack before jumping to |done|.
+    allocator.discardStack(masm);
+
+    if (outOfBounds == StringCharOutOfBounds::EmptyString) {
+      // Return the empty string for out-of-bounds access.
+      masm.movePtr(ImmGCPtr(cx_->names().empty_), scratch1);
+    } else {
+      // Return |undefined| for out-of-bounds access.
+      masm.moveValue(UndefinedValue(), output.valueReg());
+    }
+
+    // This CacheIR op is always preceded by |LinearizeForCharAccess|, so we're
+    // guaranteed to see no nested ropes.
+    masm.spectreBoundsCheck32(index, Address(str, JSString::offsetOfLength()),
+                              scratch3, &done);
+    masm.loadStringChar(str, index, scratch2, scratch1, scratch3, &loadFailed);
+  }
+
+  // Load StaticString for this char. For larger code units perform a VM call.
+  Label vmCall;
+  masm.lookupStaticString(scratch2, scratch1, cx_->staticStrings(), &vmCall);
+  masm.jump(&tagResult);
+
+  if (outOfBounds != StringCharOutOfBounds::Failure) {
+    masm.bind(&loadFailed);
+    masm.assumeUnreachable("loadStringChar can't fail for linear strings");
+  }
+
+  {
+    masm.bind(&vmCall);
+
+    AutoStubFrame stubFrame(*this);
+    stubFrame.enter(masm, scratch3);
+
+    masm.Push(scratch2);
+
+    using Fn = JSLinearString* (*)(JSContext*, int32_t);
+    callVM<Fn, js::StringFromCharCode>(masm);
+
+    stubFrame.leave(masm);
+
+    masm.storeCallPointerResult(scratch1);
+  }
+
+  if (outOfBounds != StringCharOutOfBounds::UndefinedValue) {
+    masm.bind(&tagResult);
+    masm.bind(&done);
+    masm.tagValue(JSVAL_TYPE_STRING, scratch1, output.valueReg());
+  } else {
+    masm.bind(&tagResult);
+    masm.tagValue(JSVAL_TYPE_STRING, scratch1, output.valueReg());
+    masm.bind(&done);
+  }
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitLoadStringCharResult(StringOperandId strId,
+                                                       Int32OperandId indexId,
+                                                       bool handleOOB) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  auto outOfBounds = handleOOB ? StringCharOutOfBounds::EmptyString
+                               : StringCharOutOfBounds::Failure;
+  return emitLoadStringCharResult(strId, indexId, outOfBounds);
+}
+
+bool BaselineCacheIRCompiler::emitLoadStringAtResult(StringOperandId strId,
+                                                     Int32OperandId indexId,
+                                                     bool handleOOB) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  auto outOfBounds = handleOOB ? StringCharOutOfBounds::UndefinedValue
+                               : StringCharOutOfBounds::Failure;
+  return emitLoadStringCharResult(strId, indexId, outOfBounds);
+}
+
+bool BaselineCacheIRCompiler::emitStringFromCodeResult(Int32OperandId codeId,
+                                                       StringCode stringCode) {
+  AutoOutputRegister output(*this);
+  AutoScratchRegisterMaybeOutput scratch(allocator, masm, output);
+
+  Register code = allocator.useRegister(masm, codeId);
+
+  FailurePath* failure = nullptr;
+  if (stringCode == StringCode::CodePoint) {
+    if (!addFailurePath(&failure)) {
+      return false;
+    }
+  }
+
+  if (stringCode == StringCode::CodePoint) {
+    // Note: This condition must match tryAttachStringFromCodePoint to prevent
+    // failure loops.
+    masm.branch32(Assembler::Above, code, Imm32(unicode::NonBMPMax),
+                  failure->label());
+  }
+
+  allocator.discardStack(masm);
+
+  // We pre-allocate atoms for the first UNIT_STATIC_LIMIT characters.
+  // For code units larger than that, we must do a VM call.
+  Label vmCall;
+  masm.lookupStaticString(code, scratch, cx_->staticStrings(), &vmCall);
+
+  Label done;
+  masm.jump(&done);
+
+  {
+    masm.bind(&vmCall);
+
+    AutoStubFrame stubFrame(*this);
+    stubFrame.enter(masm, scratch);
+
+    masm.Push(code);
+
+    if (stringCode == StringCode::CodeUnit) {
+      using Fn = JSLinearString* (*)(JSContext*, int32_t);
+      callVM<Fn, js::StringFromCharCode>(masm);
+    } else {
+      using Fn = JSLinearString* (*)(JSContext*, char32_t);
+      callVM<Fn, js::StringFromCodePoint>(masm);
+    }
+
+    stubFrame.leave(masm);
+    masm.storeCallPointerResult(scratch);
+  }
+
+  masm.bind(&done);
+  masm.tagValue(JSVAL_TYPE_STRING, scratch, output.valueReg());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitStringFromCharCodeResult(
+    Int32OperandId codeId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  return emitStringFromCodeResult(codeId, StringCode::CodeUnit);
+}
+
+bool BaselineCacheIRCompiler::emitStringFromCodePointResult(
+    Int32OperandId codeId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  return emitStringFromCodeResult(codeId, StringCode::CodePoint);
+}
+
+bool BaselineCacheIRCompiler::emitMathRandomResult(uint32_t rngOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  AutoScratchRegister scratch1(allocator, masm);
+  AutoScratchRegister64 scratch2(allocator, masm);
+  AutoAvailableFloatRegister scratchFloat(*this, FloatReg0);
+
+  Address rngAddr(stubAddress(rngOffset));
+  masm.loadPtr(rngAddr, scratch1);
+
+  masm.randomDouble(scratch1, scratchFloat, scratch2,
+                    output.valueReg().toRegister64());
+
+  if (js::SupportDifferentialTesting()) {
+    masm.loadConstantDouble(0.0, scratchFloat);
+  }
+
+  masm.boxDouble(scratchFloat, output.valueReg(), scratchFloat);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitReflectGetPrototypeOfResult(
+    ObjOperandId objId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  AutoScratchRegisterMaybeOutput scratch(allocator, masm, output);
+
+  Register obj = allocator.useRegister(masm, objId);
+
+  allocator.discardStack(masm);
+
+  MOZ_ASSERT(uintptr_t(TaggedProto::LazyProto) == 1);
+
+  masm.loadObjProto(obj, scratch);
+
+  Label hasProto;
+  masm.branchPtr(Assembler::Above, scratch, ImmWord(1), &hasProto);
+
+  // Call into the VM for lazy prototypes.
+  Label slow, done;
+  masm.branchPtr(Assembler::Equal, scratch, ImmWord(1), &slow);
+
+  masm.moveValue(NullValue(), output.valueReg());
+  masm.jump(&done);
+
+  masm.bind(&hasProto);
+  masm.tagValue(JSVAL_TYPE_OBJECT, scratch, output.valueReg());
+  masm.jump(&done);
+
+  {
+    masm.bind(&slow);
+
+    AutoStubFrame stubFrame(*this);
+    stubFrame.enter(masm, scratch);
+
+    masm.Push(obj);
+
+    using Fn = bool (*)(JSContext*, HandleObject, MutableHandleValue);
+    callVM<Fn, jit::GetPrototypeOf>(masm);
+
+    stubFrame.leave(masm);
+  }
+
+  masm.bind(&done);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitHasClassResult(ObjOperandId objId,
+                                                 uint32_t claspOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  Register obj = allocator.useRegister(masm, objId);
+  AutoScratchRegisterMaybeOutput scratch(allocator, masm, output);
+
+  Address claspAddr(stubAddress(claspOffset));
+  masm.loadObjClassUnsafe(obj, scratch);
+  masm.cmpPtrSet(Assembler::Equal, claspAddr, scratch.get(), scratch);
+  masm.tagValue(JSVAL_TYPE_BOOLEAN, scratch, output.valueReg());
+  return true;
+}
+
+void BaselineCacheIRCompiler::emitAtomizeString(Register str, Register temp,
+                                                Label* failure) {
+  Label isAtom;
+  masm.branchTest32(Assembler::NonZero, Address(str, JSString::offsetOfFlags()),
+                    Imm32(JSString::ATOM_BIT), &isAtom);
+  {
+    LiveRegisterSet save(GeneralRegisterSet::Volatile(),
+                         liveVolatileFloatRegs());
+    masm.PushRegsInMask(save);
+
+    using Fn = JSAtom* (*)(JSContext* cx, JSString* str);
+    masm.setupUnalignedABICall(temp);
+    masm.loadJSContext(temp);
+    masm.passABIArg(temp);
+    masm.passABIArg(str);
+    masm.callWithABI<Fn, jit::AtomizeStringNoGC>();
+    masm.storeCallPointerResult(temp);
+
+    LiveRegisterSet ignore;
+    ignore.add(temp);
+    masm.PopRegsInMaskIgnore(save, ignore);
+
+    masm.branchPtr(Assembler::Equal, temp, ImmWord(0), failure);
+    masm.mov(temp, str);
+  }
+  masm.bind(&isAtom);
+}
+
+bool BaselineCacheIRCompiler::emitSetHasStringResult(ObjOperandId setId,
+                                                     StringOperandId strId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  Register set = allocator.useRegister(masm, setId);
+  Register str = allocator.useRegister(masm, strId);
+
+  AutoScratchRegister scratch1(allocator, masm);
+  AutoScratchRegister scratch2(allocator, masm);
+  AutoScratchRegister scratch3(allocator, masm);
+  AutoScratchRegister scratch4(allocator, masm);
+
+  FailurePath* failure;
+  if (!addFailurePath(&failure)) {
+    return false;
+  }
+
+  emitAtomizeString(str, scratch1, failure->label());
+  masm.prepareHashString(str, scratch1, scratch2);
+
+  masm.tagValue(JSVAL_TYPE_STRING, str, output.valueReg());
+  masm.setObjectHasNonBigInt(set, output.valueReg(), scratch1, scratch2,
+                             scratch3, scratch4);
+  masm.tagValue(JSVAL_TYPE_BOOLEAN, scratch2, output.valueReg());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitMapHasStringResult(ObjOperandId mapId,
+                                                     StringOperandId strId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  Register map = allocator.useRegister(masm, mapId);
+  Register str = allocator.useRegister(masm, strId);
+
+  AutoScratchRegister scratch1(allocator, masm);
+  AutoScratchRegister scratch2(allocator, masm);
+  AutoScratchRegister scratch3(allocator, masm);
+  AutoScratchRegister scratch4(allocator, masm);
+
+  FailurePath* failure;
+  if (!addFailurePath(&failure)) {
+    return false;
+  }
+
+  emitAtomizeString(str, scratch1, failure->label());
+  masm.prepareHashString(str, scratch1, scratch2);
+
+  masm.tagValue(JSVAL_TYPE_STRING, str, output.valueReg());
+  masm.mapObjectHasNonBigInt(map, output.valueReg(), scratch1, scratch2,
+                             scratch3, scratch4);
+  masm.tagValue(JSVAL_TYPE_BOOLEAN, scratch2, output.valueReg());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitMapGetStringResult(ObjOperandId mapId,
+                                                     StringOperandId strId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  Register map = allocator.useRegister(masm, mapId);
+  Register str = allocator.useRegister(masm, strId);
+
+  AutoScratchRegister scratch1(allocator, masm);
+  AutoScratchRegister scratch2(allocator, masm);
+  AutoScratchRegister scratch3(allocator, masm);
+  AutoScratchRegister scratch4(allocator, masm);
+
+  FailurePath* failure;
+  if (!addFailurePath(&failure)) {
+    return false;
+  }
+
+  emitAtomizeString(str, scratch1, failure->label());
+  masm.prepareHashString(str, scratch1, scratch2);
+
+  masm.tagValue(JSVAL_TYPE_STRING, str, output.valueReg());
+  masm.mapObjectGetNonBigInt(map, output.valueReg(), scratch1,
+                             output.valueReg(), scratch2, scratch3, scratch4);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitCallNativeSetter(
+    ObjOperandId receiverId, uint32_t setterOffset, ValOperandId rhsId,
+    bool sameRealm, uint32_t nargsAndFlagsOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Register receiver = allocator.useRegister(masm, receiverId);
+  Address setterAddr(stubAddress(setterOffset));
+  ValueOperand val = allocator.useValueRegister(masm, rhsId);
+
+  AutoScratchRegister scratch(allocator, masm);
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  // Load the callee in the scratch register.
+  masm.loadPtr(setterAddr, scratch);
+
+  masm.Push(val);
+  masm.Push(receiver);
+  masm.Push(scratch);
+
+  using Fn = bool (*)(JSContext*, HandleFunction, HandleObject, HandleValue);
+  callVM<Fn, CallNativeSetter>(masm);
+
+  stubFrame.leave(masm);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitCallScriptedSetterShared(
+    ObjOperandId receiverId, uint32_t setterOffset, ValOperandId rhsId,
+    bool sameRealm, uint32_t nargsAndFlagsOffset,
+    Maybe<uint32_t> icScriptOffset) {
+  AutoScratchRegister callee(allocator, masm);
+  AutoScratchRegister scratch(allocator, masm);
+#if defined(JS_CODEGEN_X86)
+  Register code = scratch;
+#else
+  AutoScratchRegister code(allocator, masm);
+#endif
+
+  Register receiver = allocator.useRegister(masm, receiverId);
+  Address setterAddr(stubAddress(setterOffset));
+  ValueOperand val = allocator.useValueRegister(masm, rhsId);
+
+  bool isInlined = icScriptOffset.isSome();
+
+  // First, load the callee.
+  masm.loadPtr(setterAddr, callee);
+
+  if (isInlined) {
+    // If we are calling a trial-inlined setter, guard that the
+    // target has a BaselineScript.
+    FailurePath* failure;
+    if (!addFailurePath(&failure)) {
+      return false;
+    }
+    masm.loadBaselineJitCodeRaw(callee, code, failure->label());
+  }
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  if (!sameRealm) {
+    masm.switchToObjectRealm(callee, scratch);
+  }
+
+  // Align the stack such that the JitFrameLayout is aligned on
+  // JitStackAlignment.
+  masm.alignJitStackBasedOnNArgs(1, /*countIncludesThis = */ false);
+
+  // Setter is called with 1 argument, and |receiver| as thisv. Note that we use
+  // Push, not push, so that callJit will align the stack properly on ARM.
+  masm.Push(val);
+  masm.Push(TypedOrValueRegister(MIRType::Object, AnyRegister(receiver)));
+
+  // Push callee.
+  masm.Push(callee);
+
+  // Push frame descriptor.
+  masm.PushFrameDescriptorForJitCall(FrameType::BaselineStub, /* argc = */ 1);
+
+  if (isInlined) {
+    // Store icScript in the context.
+    Address icScriptAddr(stubAddress(*icScriptOffset));
+    masm.loadPtr(icScriptAddr, scratch);
+    masm.storeICScriptInJSContext(scratch);
+  }
+
+  // Load the jitcode pointer.
+  if (isInlined) {
+    // On non-x86 platforms, this pointer is still in a register
+    // after guarding on it above. On x86, we don't have enough
+    // registers and have to reload it here.
+#ifdef JS_CODEGEN_X86
+    masm.loadBaselineJitCodeRaw(callee, code);
+#endif
+  } else {
+    masm.loadJitCodeRaw(callee, code);
+  }
+
+  // Handle arguments underflow. The rhs value is no longer needed and
+  // can be used as scratch.
+  Label noUnderflow;
+  Register scratch2 = val.scratchReg();
+  masm.loadFunctionArgCount(callee, scratch2);
+  masm.branch32(Assembler::BelowOrEqual, scratch2, Imm32(1), &noUnderflow);
+
+  // Call the arguments rectifier.
+  ArgumentsRectifierKind kind = isInlined
+                                    ? ArgumentsRectifierKind::TrialInlining
+                                    : ArgumentsRectifierKind::Normal;
+  TrampolinePtr argumentsRectifier =
+      cx_->runtime()->jitRuntime()->getArgumentsRectifier(kind);
+  masm.movePtr(argumentsRectifier, code);
+
+  masm.bind(&noUnderflow);
+  masm.callJit(code);
+
+  stubFrame.leave(masm);
+
+  if (!sameRealm) {
+    masm.switchToBaselineFrameRealm(R1.scratchReg());
+  }
+
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitCallScriptedSetter(
+    ObjOperandId receiverId, uint32_t setterOffset, ValOperandId rhsId,
+    bool sameRealm, uint32_t nargsAndFlagsOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Maybe<uint32_t> icScriptOffset = mozilla::Nothing();
+  return emitCallScriptedSetterShared(receiverId, setterOffset, rhsId,
+                                      sameRealm, nargsAndFlagsOffset,
+                                      icScriptOffset);
+}
+
+bool BaselineCacheIRCompiler::emitCallInlinedSetter(
+    ObjOperandId receiverId, uint32_t setterOffset, ValOperandId rhsId,
+    uint32_t icScriptOffset, bool sameRealm, uint32_t nargsAndFlagsOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  return emitCallScriptedSetterShared(receiverId, setterOffset, rhsId,
+                                      sameRealm, nargsAndFlagsOffset,
+                                      mozilla::Some(icScriptOffset));
+}
+
+bool BaselineCacheIRCompiler::emitCallDOMSetter(ObjOperandId objId,
+                                                uint32_t jitInfoOffset,
+                                                ValOperandId rhsId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Register obj = allocator.useRegister(masm, objId);
+  ValueOperand val = allocator.useValueRegister(masm, rhsId);
+  Address jitInfoAddr(stubAddress(jitInfoOffset));
+
+  AutoScratchRegister scratch(allocator, masm);
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  // Load the JSJitInfo in the scratch register.
+  masm.loadPtr(jitInfoAddr, scratch);
+
+  masm.Push(val);
+  masm.Push(obj);
+  masm.Push(scratch);
+
+  using Fn = bool (*)(JSContext*, const JSJitInfo*, HandleObject, HandleValue);
+  callVM<Fn, CallDOMSetter>(masm);
+
+  stubFrame.leave(masm);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitCallSetArrayLength(ObjOperandId objId,
+                                                     bool strict,
+                                                     ValOperandId rhsId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Register obj = allocator.useRegister(masm, objId);
+  ValueOperand val = allocator.useValueRegister(masm, rhsId);
+
+  AutoScratchRegister scratch(allocator, masm);
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  masm.Push(Imm32(strict));
+  masm.Push(val);
+  masm.Push(obj);
+
+  using Fn = bool (*)(JSContext*, HandleObject, HandleValue, bool);
+  callVM<Fn, jit::SetArrayLength>(masm);
+
+  stubFrame.leave(masm);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitProxySet(ObjOperandId objId,
+                                           uint32_t idOffset,
+                                           ValOperandId rhsId, bool strict) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Register obj = allocator.useRegister(masm, objId);
+  ValueOperand val = allocator.useValueRegister(masm, rhsId);
+  Address idAddr(stubAddress(idOffset));
+
+  AutoScratchRegister scratch(allocator, masm);
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  // Load the jsid in the scratch register.
+  masm.loadPtr(idAddr, scratch);
+
+  masm.Push(Imm32(strict));
+  masm.Push(val);
+  masm.Push(scratch);
+  masm.Push(obj);
+
+  using Fn = bool (*)(JSContext*, HandleObject, HandleId, HandleValue, bool);
+  callVM<Fn, ProxySetProperty>(masm);
+
+  stubFrame.leave(masm);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitProxySetByValue(ObjOperandId objId,
+                                                  ValOperandId idId,
+                                                  ValOperandId rhsId,
+                                                  bool strict) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Register obj = allocator.useRegister(masm, objId);
+  ValueOperand idVal = allocator.useValueRegister(masm, idId);
+  ValueOperand val = allocator.useValueRegister(masm, rhsId);
+
+  allocator.discardStack(masm);
+
+  // We need a scratch register but we don't have any registers available on
+  // x86, so temporarily store |obj| in the frame's scratch slot.
+  int scratchOffset = BaselineFrame::reverseOffsetOfScratchValue();
+  masm.storePtr(obj, Address(baselineFrameReg(), scratchOffset));
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, obj);
+
+  // Restore |obj|. Because we entered a stub frame we first have to load
+  // the original frame pointer.
+  masm.loadPtr(Address(FramePointer, 0), obj);
+  masm.loadPtr(Address(obj, scratchOffset), obj);
+
+  masm.Push(Imm32(strict));
+  masm.Push(val);
+  masm.Push(idVal);
+  masm.Push(obj);
+
+  using Fn = bool (*)(JSContext*, HandleObject, HandleValue, HandleValue, bool);
+  callVM<Fn, ProxySetPropertyByValue>(masm);
+
+  stubFrame.leave(masm);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitCallAddOrUpdateSparseElementHelper(
+    ObjOperandId objId, Int32OperandId idId, ValOperandId rhsId, bool strict) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Register obj = allocator.useRegister(masm, objId);
+  Register id = allocator.useRegister(masm, idId);
+  ValueOperand val = allocator.useValueRegister(masm, rhsId);
+  AutoScratchRegister scratch(allocator, masm);
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  masm.Push(Imm32(strict));
+  masm.Push(val);
+  masm.Push(id);
+  masm.Push(obj);
+
+  using Fn = bool (*)(JSContext* cx, Handle<NativeObject*> obj, int32_t int_id,
+                      HandleValue v, bool strict);
+  callVM<Fn, AddOrUpdateSparseElementHelper>(masm);
+
+  stubFrame.leave(masm);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitMegamorphicSetElement(ObjOperandId objId,
+                                                        ValOperandId idId,
+                                                        ValOperandId rhsId,
+                                                        bool strict) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Register obj = allocator.useRegister(masm, objId);
+  ValueOperand idVal = allocator.useValueRegister(masm, idId);
+  ValueOperand val = allocator.useValueRegister(masm, rhsId);
+
+#ifdef JS_CODEGEN_X86
+  allocator.discardStack(masm);
+  // We need a scratch register but we don't have any registers available on
+  // x86, so temporarily store |obj| in the frame's scratch slot.
+  int scratchOffset = BaselineFrame::reverseOffsetOfScratchValue();
+  masm.storePtr(obj, Address(baselineFrameReg_, scratchOffset));
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, obj);
+
+  // Restore |obj|. Because we entered a stub frame we first have to load
+  // the original frame pointer.
+  masm.loadPtr(Address(FramePointer, 0), obj);
+  masm.loadPtr(Address(obj, scratchOffset), obj);
+#else
+  AutoScratchRegister scratch(allocator, masm);
+
+  allocator.discardStack(masm);
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+#endif
+
+  masm.Push(Imm32(strict));
+  masm.Push(val);
+  masm.Push(idVal);
+  masm.Push(obj);
+
+  using Fn = bool (*)(JSContext*, HandleObject, HandleValue, HandleValue, bool);
+  callVM<Fn, SetElementMegamorphic<false>>(masm);
+
+  stubFrame.leave(masm);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitReturnFromIC() {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  allocator.discardStack(masm);
+  if (JitOptions.enableICFramePointers) {
+    PopICFrameRegs(masm);
+  }
+  EmitReturnFromIC(masm);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitLoadArgumentFixedSlot(ValOperandId resultId,
+                                                        uint8_t slotIndex) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  ValueOperand resultReg = allocator.defineValueRegister(masm, resultId);
+  Address addr = allocator.addressOf(masm, BaselineFrameSlot(slotIndex));
+  masm.loadValue(addr, resultReg);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitLoadArgumentDynamicSlot(ValOperandId resultId,
+                                                          Int32OperandId argcId,
+                                                          uint8_t slotIndex) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  ValueOperand resultReg = allocator.defineValueRegister(masm, resultId);
+  Register argcReg = allocator.useRegister(masm, argcId);
+  BaseValueIndex addr =
+      allocator.addressOf(masm, argcReg, BaselineFrameSlot(slotIndex));
+  masm.loadValue(addr, resultReg);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitGuardDOMExpandoMissingOrGuardShape(
+    ValOperandId expandoId, uint32_t shapeOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  ValueOperand val = allocator.useValueRegister(masm, expandoId);
+  AutoScratchRegister shapeScratch(allocator, masm);
+  AutoScratchRegister objScratch(allocator, masm);
+  Address shapeAddr(stubAddress(shapeOffset));
+
+  FailurePath* failure;
+  if (!addFailurePath(&failure)) {
+    return false;
+  }
+
+  Label done;
+  masm.branchTestUndefined(Assembler::Equal, val, &done);
+
+  masm.debugAssertIsObject(val);
+  masm.loadPtr(shapeAddr, shapeScratch);
+  masm.unboxObject(val, objScratch);
+  // The expando object is not used in this case, so we don't need Spectre
+  // mitigations.
+  masm.branchTestObjShapeNoSpectreMitigations(Assembler::NotEqual, objScratch,
+                                              shapeScratch, failure->label());
+
+  masm.bind(&done);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitLoadDOMExpandoValueGuardGeneration(
+    ObjOperandId objId, uint32_t expandoAndGenerationOffset,
+    uint32_t generationOffset, ValOperandId resultId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Register obj = allocator.useRegister(masm, objId);
+  Address expandoAndGenerationAddr(stubAddress(expandoAndGenerationOffset));
+  Address generationAddr(stubAddress(generationOffset));
+
+  AutoScratchRegister scratch(allocator, masm);
+  ValueOperand output = allocator.defineValueRegister(masm, resultId);
+
+  FailurePath* failure;
+  if (!addFailurePath(&failure)) {
+    return false;
+  }
+
+  masm.loadPtr(Address(obj, ProxyObject::offsetOfReservedSlots()), scratch);
+  Address expandoAddr(scratch,
+                      js::detail::ProxyReservedSlots::offsetOfPrivateSlot());
+
+  // Load the ExpandoAndGeneration* in the output scratch register and guard
+  // it matches the proxy's ExpandoAndGeneration.
+  masm.loadPtr(expandoAndGenerationAddr, output.scratchReg());
+  masm.branchPrivatePtr(Assembler::NotEqual, expandoAddr, output.scratchReg(),
+                        failure->label());
+
+  // Guard expandoAndGeneration->generation matches the expected generation.
+  masm.branch64(
+      Assembler::NotEqual,
+      Address(output.scratchReg(), ExpandoAndGeneration::offsetOfGeneration()),
+      generationAddr, scratch, failure->label());
+
+  // Load expandoAndGeneration->expando into the output Value register.
+  masm.loadValue(
+      Address(output.scratchReg(), ExpandoAndGeneration::offsetOfExpando()),
+      output);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::init(CacheKind kind) {
+  if (!allocator.init()) {
+    return false;
+  }
+
+  size_t numInputs = writer_.numInputOperands();
+  MOZ_ASSERT(numInputs == NumInputsForCacheKind(kind));
+
+  // Baseline passes the first 2 inputs in R0/R1, other Values are stored on
+  // the stack.
+  size_t numInputsInRegs = std::min(numInputs, size_t(2));
+  AllocatableGeneralRegisterSet available =
+      BaselineICAvailableGeneralRegs(numInputsInRegs);
+
+  switch (kind) {
+    case CacheKind::NewArray:
+    case CacheKind::NewObject:
+    case CacheKind::GetIntrinsic:
+      MOZ_ASSERT(numInputs == 0);
+      outputUnchecked_.emplace(R0);
+      break;
+    case CacheKind::GetProp:
+    case CacheKind::TypeOf:
+    case CacheKind::ToPropertyKey:
+    case CacheKind::GetIterator:
+    case CacheKind::OptimizeSpreadCall:
+    case CacheKind::OptimizeGetIterator:
+    case CacheKind::ToBool:
+    case CacheKind::UnaryArith:
+      MOZ_ASSERT(numInputs == 1);
+      allocator.initInputLocation(0, R0);
+      outputUnchecked_.emplace(R0);
+      break;
+    case CacheKind::Compare:
+    case CacheKind::GetElem:
+    case CacheKind::GetPropSuper:
+    case CacheKind::In:
+    case CacheKind::HasOwn:
+    case CacheKind::CheckPrivateField:
+    case CacheKind::InstanceOf:
+    case CacheKind::BinaryArith:
+      MOZ_ASSERT(numInputs == 2);
+      allocator.initInputLocation(0, R0);
+      allocator.initInputLocation(1, R1);
+      outputUnchecked_.emplace(R0);
+      break;
+    case CacheKind::SetProp:
+      MOZ_ASSERT(numInputs == 2);
+      allocator.initInputLocation(0, R0);
+      allocator.initInputLocation(1, R1);
+      break;
+    case CacheKind::GetElemSuper:
+      MOZ_ASSERT(numInputs == 3);
+      allocator.initInputLocation(0, BaselineFrameSlot(0));
+      allocator.initInputLocation(1, R1);
+      allocator.initInputLocation(2, R0);
+      outputUnchecked_.emplace(R0);
+      break;
+    case CacheKind::SetElem:
+      MOZ_ASSERT(numInputs == 3);
+      allocator.initInputLocation(0, R0);
+      allocator.initInputLocation(1, R1);
+      allocator.initInputLocation(2, BaselineFrameSlot(0));
+      break;
+    case CacheKind::GetName:
+    case CacheKind::BindName:
+      MOZ_ASSERT(numInputs == 1);
+      allocator.initInputLocation(0, R0.scratchReg(), JSVAL_TYPE_OBJECT);
+#if defined(JS_NUNBOX32)
+      // availableGeneralRegs can't know that GetName/BindName is only using
+      // the payloadReg and not typeReg on x86.
+      available.add(R0.typeReg());
+#endif
+      outputUnchecked_.emplace(R0);
+      break;
+    case CacheKind::Call:
+      MOZ_ASSERT(numInputs == 1);
+      allocator.initInputLocation(0, R0.scratchReg(), JSVAL_TYPE_INT32);
+#if defined(JS_NUNBOX32)
+      // availableGeneralRegs can't know that Call is only using
+      // the payloadReg and not typeReg on x86.
+      available.add(R0.typeReg());
+#endif
+      outputUnchecked_.emplace(R0);
+      break;
+    case CacheKind::CloseIter:
+      MOZ_ASSERT(numInputs == 1);
+      allocator.initInputLocation(0, R0.scratchReg(), JSVAL_TYPE_OBJECT);
+#if defined(JS_NUNBOX32)
+      // availableGeneralRegs can't know that CloseIter is only using
+      // the payloadReg and not typeReg on x86.
+      available.add(R0.typeReg());
+#endif
+      break;
+  }
+
+  // Baseline doesn't allocate float registers so none of them are live.
+  liveFloatRegs_ = LiveFloatRegisterSet(FloatRegisterSet());
+
+  if (JitOptions.enableICFramePointers) {
+    baselineFrameReg_ = available.takeAny();
+  }
+
+  allocator.initAvailableRegs(available);
+  return true;
+}
+
+static void ResetEnteredCounts(const ICEntry* icEntry) {
+  ICStub* stub = icEntry->firstStub();
+  while (true) {
+    stub->resetEnteredCount();
+    if (stub->isFallback()) {
+      return;
+    }
+    stub = stub->toCacheIRStub()->next();
+  }
+}
+
+static const uint32_t MaxFoldedShapes = 16;
+
+const JSClass ShapeListObject::class_ = {"JIT ShapeList", 0, &classOps_};
+
+const JSClassOps ShapeListObject::classOps_ = {
+    nullptr,                 // addProperty
+    nullptr,                 // delProperty
+    nullptr,                 // enumerate
+    nullptr,                 // newEnumerate
+    nullptr,                 // resolve
+    nullptr,                 // mayResolve
+    nullptr,                 // finalize
+    nullptr,                 // call
+    nullptr,                 // construct
+    ShapeListObject::trace,  // trace
+};
+
+/* static */ ShapeListObject* ShapeListObject::create(JSContext* cx) {
+  NativeObject* obj = NewTenuredObjectWithGivenProto(cx, &class_, nullptr);
+  if (!obj) {
+    return nullptr;
+  }
+
+  // Register this object so the GC can sweep its weak pointers.
+  if (!cx->zone()->registerObjectWithWeakPointers(obj)) {
+    return nullptr;
+  }
+
+  return &obj->as<ShapeListObject>();
+}
+
+Shape* ShapeListObject::get(uint32_t index) {
+  Value value = ListObject::get(index);
+  return static_cast<Shape*>(value.toPrivate());
+}
+
+void ShapeListObject::trace(JSTracer* trc, JSObject* obj) {
+  if (trc->traceWeakEdges()) {
+    obj->as<ShapeListObject>().traceWeak(trc);
+  }
+}
+
+bool ShapeListObject::traceWeak(JSTracer* trc) {
+  const HeapSlot* src = elements_;
+  const HeapSlot* end = src + getDenseInitializedLength();
+  HeapSlot* dst = elements_;
+  while (src != end) {
+    Shape* shape = static_cast<Shape*>(src->toPrivate());
+    MOZ_ASSERT(shape->is<Shape>());
+    if (TraceManuallyBarrieredWeakEdge(trc, &shape, "ShapeListObject shape")) {
+      dst->unbarrieredSet(PrivateValue(shape));
+      dst++;
+    }
+    src++;
+  }
+
+  MOZ_ASSERT(dst <= end);
+  size_t length = dst - elements_;
+  setDenseInitializedLength(length);
+
+  return length != 0;
+}
+
+bool js::jit::TryFoldingStubs(JSContext* cx, ICFallbackStub* fallback,
+                              JSScript* script, ICScript* icScript) {
+  ICEntry* icEntry = icScript->icEntryForStub(fallback);
+  ICStub* entryStub = icEntry->firstStub();
+
+  // Don't fold unless there are at least two stubs.
+  if (entryStub == fallback) {
+    return true;
+  }
+  ICCacheIRStub* firstStub = entryStub->toCacheIRStub();
+  if (firstStub->next()->isFallback()) {
+    return true;
+  }
+
+  const uint8_t* firstStubData = firstStub->stubDataStart();
+  const CacheIRStubInfo* stubInfo = firstStub->stubInfo();
+
+  // Check to see if:
+  //   a) all of the stubs in this chain have the exact same code.
+  //   b) all of the stubs have the same stub field data, except
+  //      for a single GuardShape where they differ.
+  //   c) at least one stub after the first has a non-zero entry count.
+  //   d) All shapes in the GuardShape have the same realm.
+  //
+  // If all of these conditions hold, then we generate a single stub
+  // that covers all the existing cases by replacing GuardShape with
+  // GuardMultipleShapes.
+
+  uint32_t numActive = 0;
+  Maybe<uint32_t> foldableFieldOffset;
+  RootedValue shape(cx);
+  RootedValueVector shapeList(cx);
+
+  // Try to add a shape to the list. Can fail on OOM or for cross-realm shapes.
+  // Returns true if the shape was successfully added to the list, and false
+  // (with no pending exception) otherwise.
+  auto addShape = [&shapeList, cx](uintptr_t rawShape) -> bool {
+    Shape* shape = reinterpret_cast<Shape*>(rawShape);
+    // Only add same realm shapes.
+    if (shape->realm() != cx->realm()) {
+      return false;
+    }
+
+    gc::ReadBarrier(shape);
+
+    if (!shapeList.append(PrivateValue(shape))) {
+      cx->recoverFromOutOfMemory();
+      return false;
+    }
+    return true;
+  };
+
+  for (ICCacheIRStub* other = firstStub->nextCacheIR(); other;
+       other = other->nextCacheIR()) {
+    // Verify that the stubs share the same code.
+    if (other->stubInfo() != stubInfo) {
+      return true;
+    }
+    const uint8_t* otherStubData = other->stubDataStart();
+
+    if (other->enteredCount() > 0) {
+      numActive++;
+    }
+
+    uint32_t fieldIndex = 0;
+    size_t offset = 0;
+    while (stubInfo->fieldType(fieldIndex) != StubField::Type::Limit) {
+      StubField::Type fieldType = stubInfo->fieldType(fieldIndex);
+
+      if (StubField::sizeIsWord(fieldType)) {
+        uintptr_t firstRaw = stubInfo->getStubRawWord(firstStubData, offset);
+        uintptr_t otherRaw = stubInfo->getStubRawWord(otherStubData, offset);
+
+        if (firstRaw != otherRaw) {
+          if (fieldType != StubField::Type::WeakShape) {
+            // Case 1: a field differs that is not a Shape. We only support
+            // folding GuardShape to GuardMultipleShapes.
+            return true;
+          }
+          if (foldableFieldOffset.isNothing()) {
+            // Case 2: this is the first field where the stub data differs.
+            foldableFieldOffset.emplace(offset);
+            if (!addShape(firstRaw) || !addShape(otherRaw)) {
+              return true;
+            }
+          } else if (*foldableFieldOffset == offset) {
+            // Case 3: this is the corresponding offset in a different stub.
+            if (!addShape(otherRaw)) {
+              return true;
+            }
+          } else {
+            // Case 4: we have found more than one field that differs.
+            return true;
+          }
+        }
+      } else {
+        MOZ_ASSERT(StubField::sizeIsInt64(fieldType));
+
+        // We do not support folding any ops with int64-sized fields.
+        if (stubInfo->getStubRawInt64(firstStubData, offset) !=
+            stubInfo->getStubRawInt64(otherStubData, offset)) {
+          return true;
+        }
+      }
+
+      offset += StubField::sizeInBytes(fieldType);
+      fieldIndex++;
+    }
+
+    // We should never attach two completely identical stubs.
+    MOZ_ASSERT(foldableFieldOffset.isSome());
+  }
+
+  if (numActive == 0) {
+    return true;
+  }
+
+  // Clone the CacheIR, replacing GuardShape with GuardMultipleShapes.
+  CacheIRWriter writer(cx);
+  CacheIRReader reader(stubInfo);
+  CacheIRCloner cloner(firstStub);
+
+  // Initialize the operands.
+  CacheKind cacheKind = stubInfo->kind();
+  for (uint32_t i = 0; i < NumInputsForCacheKind(cacheKind); i++) {
+    writer.setInputOperandId(i);
+  }
+
+  bool success = false;
+  while (reader.more()) {
+    CacheOp op = reader.readOp();
+    switch (op) {
+      case CacheOp::GuardShape: {
+        ObjOperandId objId = reader.objOperandId();
+        uint32_t shapeOffset = reader.stubOffset();
+        if (shapeOffset == *foldableFieldOffset) {
+          // Ensure that the allocation of the ShapeListObject doesn't trigger a
+          // GC and free the stubInfo we're currently reading. Note that
+          // AutoKeepJitScripts isn't sufficient, because optimized stubs can be
+          // discarded even if the JitScript is preserved.
+          gc::AutoSuppressGC suppressGC(cx);
+
+          Rooted<ShapeListObject*> shapeObj(cx, ShapeListObject::create(cx));
+          if (!shapeObj) {
+            return false;
+          }
+          for (uint32_t i = 0; i < shapeList.length(); i++) {
+            if (!shapeObj->append(cx, shapeList[i])) {
+              return false;
+            }
+
+            MOZ_ASSERT(static_cast<Shape*>(shapeList[i].toPrivate())->realm() ==
+                       shapeObj->realm());
+          }
+
+          writer.guardMultipleShapes(objId, shapeObj);
+          success = true;
+        } else {
+          WeakHeapPtr<Shape*>& ptr =
+              stubInfo->getStubField<StubField::Type::WeakShape>(firstStub,
+                                                                 shapeOffset);
+          writer.guardShape(objId, ptr.unbarrieredGet());
+        }
+        break;
+      }
+      default:
+        cloner.cloneOp(op, reader, writer);
+        break;
+    }
+  }
+  if (!success) {
+    // If the shape field that differed was not part of a GuardShape,
+    // we can't fold these stubs together.
+    return true;
+  }
+
+  // Replace the existing stubs with the new folded stub.
+  fallback->discardStubs(cx->zone(), icEntry);
+
+  ICAttachResult result = AttachBaselineCacheIRStub(
+      cx, writer, cacheKind, script, icScript, fallback, "StubFold");
+  if (result == ICAttachResult::OOM) {
+    ReportOutOfMemory(cx);
+    return false;
+  }
+  MOZ_ASSERT(result == ICAttachResult::Attached);
+
+  fallback->setMayHaveFoldedStub();
+  return true;
+}
+
+static bool AddToFoldedStub(JSContext* cx, const CacheIRWriter& writer,
+                            ICScript* icScript, ICFallbackStub* fallback) {
+  ICEntry* icEntry = icScript->icEntryForStub(fallback);
+  ICStub* entryStub = icEntry->firstStub();
+
+  // We only update folded stubs if they're the only stub in the IC.
+  if (entryStub == fallback) {
+    return false;
+  }
+  ICCacheIRStub* stub = entryStub->toCacheIRStub();
+  if (!stub->next()->isFallback()) {
+    return false;
+  }
+
+  const CacheIRStubInfo* stubInfo = stub->stubInfo();
+  const uint8_t* stubData = stub->stubDataStart();
+
+  Maybe<uint32_t> shapeFieldOffset;
+  RootedValue newShape(cx);
+  Rooted<ShapeListObject*> foldedShapes(cx);
+
+  CacheIRReader stubReader(stubInfo);
+  CacheIRReader newReader(writer);
+  while (newReader.more() && stubReader.more()) {
+    CacheOp newOp = newReader.readOp();
+    CacheOp stubOp = stubReader.readOp();
+    switch (stubOp) {
+      case CacheOp::GuardMultipleShapes: {
+        // Check that the new stub has a corresponding GuardShape.
+        if (newOp != CacheOp::GuardShape) {
+          return false;
+        }
+
+        // Check that the object being guarded is the same.
+        if (newReader.objOperandId() != stubReader.objOperandId()) {
+          return false;
+        }
+
+        // Check that the field offset is the same.
+        uint32_t newShapeOffset = newReader.stubOffset();
+        uint32_t stubShapesOffset = stubReader.stubOffset();
+        if (newShapeOffset != stubShapesOffset) {
+          return false;
+        }
+        MOZ_ASSERT(shapeFieldOffset.isNothing());
+        shapeFieldOffset.emplace(newShapeOffset);
+
+        // Get the shape from the new stub
+        StubField shapeField =
+            writer.readStubField(newShapeOffset, StubField::Type::WeakShape);
+        Shape* shape = reinterpret_cast<Shape*>(shapeField.asWord());
+        newShape = PrivateValue(shape);
+
+        // Get the shape array from the old stub.
+        JSObject* shapeList = stubInfo->getStubField<StubField::Type::JSObject>(
+            stub, stubShapesOffset);
+        foldedShapes = &shapeList->as<ShapeListObject>();
+        MOZ_ASSERT(foldedShapes->compartment() == shape->compartment());
+
+        // Don't add a shape if it's from a different realm than the first
+        // shape.
+        //
+        // Since the list was created in the realm which guarded all the shapes
+        // added to it, we can use its realm to check and ensure we're not
+        // adding a cross-realm shape.
+        //
+        // The assert verifies this property by checking the first element has
+        // the same realm (and since everything in the list has the same realm,
+        // checking the first element suffices)
+        MOZ_ASSERT_IF(!foldedShapes->isEmpty(),
+                      foldedShapes->get(0)->realm() == foldedShapes->realm());
+        if (foldedShapes->realm() != shape->realm()) {
+          return false;
+        }
+
+        break;
+      }
+      default: {
+        // Check that the op is the same.
+        if (newOp != stubOp) {
+          return false;
+        }
+
+        // Check that the arguments are the same.
+        uint32_t argLength = CacheIROpInfos[size_t(newOp)].argLength;
+        for (uint32_t i = 0; i < argLength; i++) {
+          if (newReader.readByte() != stubReader.readByte()) {
+            return false;
+          }
+        }
+      }
+    }
+  }
+
+  if (shapeFieldOffset.isNothing()) {
+    // The stub did not contain the GuardMultipleShapes op. This can happen if a
+    // folded stub has been discarded by GC sweeping.
+    return false;
+  }
+
+  // Check to verify that all the other stub fields are the same.
+  if (!writer.stubDataEqualsIgnoring(stubData, *shapeFieldOffset)) {
+    return false;
+  }
+
+  // Limit the maximum number of shapes we will add before giving up.
+  if (foldedShapes->length() == MaxFoldedShapes) {
+    return false;
+  }
+
+  if (!foldedShapes->append(cx, newShape)) {
+    cx->recoverFromOutOfMemory();
+    return false;
+  }
+
+  return true;
+}
+
+ICAttachResult js::jit::AttachBaselineCacheIRStub(
+    JSContext* cx, const CacheIRWriter& writer, CacheKind kind,
+    JSScript* outerScript, ICScript* icScript, ICFallbackStub* stub,
+    const char* name) {
+  // We shouldn't GC or report OOM (or any other exception) here.
+  AutoAssertNoPendingException aanpe(cx);
+  JS::AutoCheckCannotGC nogc;
+
+  if (writer.tooLarge()) {
+    return ICAttachResult::TooLarge;
+  }
+  if (writer.oom()) {
+    return ICAttachResult::OOM;
+  }
+  MOZ_ASSERT(!writer.failed());
+
+  // Just a sanity check: the caller should ensure we don't attach an
+  // unlimited number of stubs.
+#ifdef DEBUG
+  static const size_t MaxOptimizedCacheIRStubs = 16;
+  MOZ_ASSERT(stub->numOptimizedStubs() < MaxOptimizedCacheIRStubs);
+#endif
+
+  constexpr uint32_t stubDataOffset = sizeof(ICCacheIRStub);
+  static_assert(stubDataOffset % sizeof(uint64_t) == 0,
+                "Stub fields must be aligned");
+
+  JitZone* jitZone = cx->zone()->jitZone();
+
+  // Check if we already have JitCode for this stub.
+  CacheIRStubInfo* stubInfo;
+  CacheIRStubKey::Lookup lookup(kind, ICStubEngine::Baseline,
+                                writer.codeStart(), writer.codeLength());
+
+  JitCode* code = jitZone->getBaselineCacheIRStubCode(lookup, &stubInfo);
+
+  if (!code && !IsPortableBaselineInterpreterEnabled()) {
+    // We have to generate stub code.
+    TempAllocator temp(&cx->tempLifoAlloc());
+    JitContext jctx(cx);
+    BaselineCacheIRCompiler comp(cx, temp, writer, stubDataOffset);
+    if (!comp.init(kind)) {
+      return ICAttachResult::OOM;
+    }
+
+    code = comp.compile();
+    if (!code) {
+      return ICAttachResult::OOM;
+    }
+
+    comp.perfSpewer().saveProfile(code, name);
+
+    // Allocate the shared CacheIRStubInfo. Note that the
+    // putBaselineCacheIRStubCode call below will transfer ownership
+    // to the stub code HashMap, so we don't have to worry about freeing
+    // it below.
+    MOZ_ASSERT(!stubInfo);
+    stubInfo =
+        CacheIRStubInfo::New(kind, ICStubEngine::Baseline, comp.makesGCCalls(),
+                             stubDataOffset, writer);
+    if (!stubInfo) {
+      return ICAttachResult::OOM;
+    }
+
+    CacheIRStubKey key(stubInfo);
+    if (!jitZone->putBaselineCacheIRStubCode(lookup, key, code)) {
+      return ICAttachResult::OOM;
+    }
+  } else if (!stubInfo) {
+    MOZ_ASSERT(IsPortableBaselineInterpreterEnabled());
+
+    // Portable baseline interpreter case. We want to generate the
+    // CacheIR bytecode but not compile it to native code.
+    //
+    // We lie that all stubs make GC calls; this is simpler than
+    // iterating over ops to determine if it is actually the base, and
+    // we don't invoke the BaselineCacheIRCompiler so we otherwise
+    // don't know for sure.
+    stubInfo = CacheIRStubInfo::New(kind, ICStubEngine::Baseline,
+                                    /* makes GC calls = */ true, stubDataOffset,
+                                    writer);
+    if (!stubInfo) {
+      return ICAttachResult::OOM;
+    }
+
+    CacheIRStubKey key(stubInfo);
+    if (!jitZone->putBaselineCacheIRStubCode(lookup, key,
+                                             /* stubCode = */ nullptr)) {
+      return ICAttachResult::OOM;
+    }
+  }
+  MOZ_ASSERT_IF(IsBaselineInterpreterEnabled(), code);
+  MOZ_ASSERT(stubInfo);
+  MOZ_ASSERT(stubInfo->stubDataSize() == writer.stubDataSize());
+
+  ICEntry* icEntry = icScript->icEntryForStub(stub);
+
+  // Ensure we don't attach duplicate stubs. This can happen if a stub failed
+  // for some reason and the IR generator doesn't check for exactly the same
+  // conditions.
+  for (ICStub* iter = icEntry->firstStub(); iter != stub;
+       iter = iter->toCacheIRStub()->next()) {
+    auto otherStub = iter->toCacheIRStub();
+    if (otherStub->stubInfo() != stubInfo) {
+      continue;
+    }
+    if (!writer.stubDataEquals(otherStub->stubDataStart())) {
+      continue;
+    }
+
+    // We found a stub that's exactly the same as the stub we're about to
+    // attach. Just return nullptr, the caller should do nothing in this
+    // case.
+    JitSpew(JitSpew_BaselineICFallback,
+            "Tried attaching identical stub for (%s:%u:%u)",
+            outerScript->filename(), outerScript->lineno(),
+            outerScript->column().oneOriginValue());
+    return ICAttachResult::DuplicateStub;
+  }
+
+  // Try including this case in an existing folded stub.
+  if (stub->mayHaveFoldedStub() &&
+      AddToFoldedStub(cx, writer, icScript, stub)) {
+    // Instead of adding a new stub, we have added a new case to an existing
+    // folded stub. We do not have to invalidate Warp, because the
+    // ShapeListObject that stores the cases is shared between baseline and
+    // Warp. Reset the entered count for the fallback stub so that we can still
+    // transpile, and reset the bailout counter if we have already been
+    // transpiled.
+    stub->resetEnteredCount();
+    JSScript* owningScript = nullptr;
+    if (cx->zone()->jitZone()->hasStubFoldingBailoutData(outerScript)) {
+      owningScript = cx->zone()->jitZone()->stubFoldingBailoutParent();
+    } else {
+      owningScript = icScript->isInlined()
+                         ? icScript->inliningRoot()->owningScript()
+                         : outerScript;
+    }
+    cx->zone()->jitZone()->clearStubFoldingBailoutData();
+    if (stub->usedByTranspiler() && owningScript->hasIonScript()) {
+      owningScript->ionScript()->resetNumFixableBailouts();
+    } else {
+      // Update the last IC counter if this is not a bailout from Ion.
+      owningScript->updateLastICStubCounter();
+    }
+    return ICAttachResult::Attached;
+  }
+
+  // Time to allocate and attach a new stub.
+
+  size_t bytesNeeded = stubInfo->stubDataOffset() + stubInfo->stubDataSize();
+
+  void* newStubMem = jitZone->stubSpace()->alloc(bytesNeeded);
+  if (!newStubMem) {
+    return ICAttachResult::OOM;
+  }
+
+  // Resetting the entered counts on the IC chain makes subsequent reasoning
+  // about the chain much easier.
+  ResetEnteredCounts(icEntry);
+
+  switch (stub->trialInliningState()) {
+    case TrialInliningState::Initial:
+    case TrialInliningState::Candidate:
+      stub->setTrialInliningState(writer.trialInliningState());
+      break;
+    case TrialInliningState::MonomorphicInlined:
+      stub->setTrialInliningState(TrialInliningState::Failure);
+      break;
+    case TrialInliningState::Inlined:
+      stub->setTrialInliningState(TrialInliningState::Failure);
+      icScript->removeInlinedChild(stub->pcOffset());
+      break;
+    case TrialInliningState::Failure:
+      break;
+  }
+
+  auto newStub = new (newStubMem) ICCacheIRStub(code, stubInfo);
+  writer.copyStubData(newStub->stubDataStart());
+  newStub->setTypeData(writer.typeData());
+  stub->addNewStub(icEntry, newStub);
+
+  JSScript* owningScript = icScript->isInlined()
+                               ? icScript->inliningRoot()->owningScript()
+                               : outerScript;
+  owningScript->updateLastICStubCounter();
+  return ICAttachResult::Attached;
+}
+
+uint8_t* ICCacheIRStub::stubDataStart() {
+  return reinterpret_cast<uint8_t*>(this) + stubInfo_->stubDataOffset();
+}
+
+bool BaselineCacheIRCompiler::emitCallStringObjectConcatResult(
+    ValOperandId lhsId, ValOperandId rhsId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  ValueOperand lhs = allocator.useValueRegister(masm, lhsId);
+  ValueOperand rhs = allocator.useValueRegister(masm, rhsId);
+
+  AutoScratchRegister scratch(allocator, masm);
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  masm.pushValue(rhs);
+  masm.pushValue(lhs);
+
+  using Fn = bool (*)(JSContext*, HandleValue, HandleValue, MutableHandleValue);
+  callVM<Fn, DoConcatStringObject>(masm);
+
+  stubFrame.leave(masm);
+  return true;
+}
+
+// The value of argc entering the call IC is not always the value of
+// argc entering the callee. (For example, argc for a spread call IC
+// is always 1, but argc for the callee is the length of the array.)
+// In these cases, we update argc as part of the call op itself, to
+// avoid modifying input operands while it is still possible to fail a
+// guard. We also limit callee argc to a reasonable value to avoid
+// blowing the stack limit.
+bool BaselineCacheIRCompiler::updateArgc(CallFlags flags, Register argcReg,
+                                         Register scratch) {
+  CallFlags::ArgFormat format = flags.getArgFormat();
+  switch (format) {
+    case CallFlags::Standard:
+      // Standard calls have no extra guards, and argc is already correct.
+      return true;
+    case CallFlags::FunCall:
+      // fun_call has no extra guards, and argc will be corrected in
+      // pushFunCallArguments.
+      return true;
+    case CallFlags::FunApplyNullUndefined:
+      // argc must be 0 if null or undefined is passed as second argument to
+      // |apply|.
+      masm.move32(Imm32(0), argcReg);
+      return true;
+    default:
+      break;
+  }
+
+  // We need to guard the length of the arguments.
+  FailurePath* failure;
+  if (!addFailurePath(&failure)) {
+    return false;
+  }
+
+  // Load callee argc into scratch.
+  switch (flags.getArgFormat()) {
+    case CallFlags::Spread:
+    case CallFlags::FunApplyArray: {
+      // Load the length of the elements.
+      BaselineFrameSlot slot(flags.isConstructing());
+      masm.unboxObject(allocator.addressOf(masm, slot), scratch);
+      masm.loadPtr(Address(scratch, NativeObject::offsetOfElements()), scratch);
+      masm.load32(Address(scratch, ObjectElements::offsetOfLength()), scratch);
+      break;
+    }
+    case CallFlags::FunApplyArgsObj: {
+      // Load the arguments object length.
+      BaselineFrameSlot slot(0);
+      masm.unboxObject(allocator.addressOf(masm, slot), scratch);
+      masm.loadArgumentsObjectLength(scratch, scratch, failure->label());
+      break;
+    }
+    default:
+      MOZ_CRASH("Unknown arg format");
+  }
+
+  // Ensure that callee argc does not exceed the limit.
+  masm.branch32(Assembler::Above, scratch, Imm32(JIT_ARGS_LENGTH_MAX),
+                failure->label());
+
+  // We're past the final guard. Update argc with the new value.
+  masm.move32(scratch, argcReg);
+
+  return true;
+}
+
+void BaselineCacheIRCompiler::pushArguments(Register argcReg,
+                                            Register calleeReg,
+                                            Register scratch, Register scratch2,
+                                            CallFlags flags, uint32_t argcFixed,
+                                            bool isJitCall) {
+  switch (flags.getArgFormat()) {
+    case CallFlags::Standard:
+      pushStandardArguments(argcReg, scratch, scratch2, argcFixed, isJitCall,
+                            flags.isConstructing());
+      break;
+    case CallFlags::Spread:
+      pushArrayArguments(argcReg, scratch, scratch2, isJitCall,
+                         flags.isConstructing());
+      break;
+    case CallFlags::FunCall:
+      pushFunCallArguments(argcReg, calleeReg, scratch, scratch2, argcFixed,
+                           isJitCall);
+      break;
+    case CallFlags::FunApplyArgsObj:
+      pushFunApplyArgsObj(argcReg, calleeReg, scratch, scratch2, isJitCall);
+      break;
+    case CallFlags::FunApplyArray:
+      pushArrayArguments(argcReg, scratch, scratch2, isJitCall,
+                         /*isConstructing =*/false);
+      break;
+    case CallFlags::FunApplyNullUndefined:
+      pushFunApplyNullUndefinedArguments(calleeReg, isJitCall);
+      break;
+    default:
+      MOZ_CRASH("Invalid arg format");
+  }
+}
+
+void BaselineCacheIRCompiler::pushStandardArguments(
+    Register argcReg, Register scratch, Register scratch2, uint32_t argcFixed,
+    bool isJitCall, bool isConstructing) {
+  MOZ_ASSERT(enteredStubFrame_);
+
+  // The arguments to the call IC are pushed on the stack left-to-right.
+  // Our calling conventions want them right-to-left in the callee, so
+  // we duplicate them on the stack in reverse order.
+
+  int additionalArgc = 1 + !isJitCall + isConstructing;
+  if (argcFixed < MaxUnrolledArgCopy) {
+#ifdef DEBUG
+    Label ok;
+    masm.branch32(Assembler::Equal, argcReg, Imm32(argcFixed), &ok);
+    masm.assumeUnreachable("Invalid argcFixed value");
+    masm.bind(&ok);
+#endif
+
+    size_t realArgc = argcFixed + additionalArgc;
+
+    if (isJitCall) {
+      masm.alignJitStackBasedOnNArgs(realArgc, /*countIncludesThis = */ true);
+    }
+
+    for (size_t i = 0; i < realArgc; ++i) {
+      masm.pushValue(Address(
+          FramePointer, BaselineStubFrameLayout::Size() + i * sizeof(Value)));
+    }
+  } else {
+    MOZ_ASSERT(argcFixed == MaxUnrolledArgCopy);
+
+    // argPtr initially points to the last argument. Skip the stub frame.
+    Register argPtr = scratch2;
+    Address argAddress(FramePointer, BaselineStubFrameLayout::Size());
+    masm.computeEffectiveAddress(argAddress, argPtr);
+
+    // countReg contains the total number of arguments to copy.
+    // In addition to the actual arguments, we have to copy hidden arguments.
+    // We always have to copy |this|.
+    // If we are constructing, we have to copy |newTarget|.
+    // If we are not a jit call, we have to copy |callee|.
+    // We use a scratch register to avoid clobbering argc, which is an input
+    // reg.
+    Register countReg = scratch;
+    masm.move32(argcReg, countReg);
+    masm.add32(Imm32(additionalArgc), countReg);
+
+    // Align the stack such that the JitFrameLayout is aligned on the
+    // JitStackAlignment.
+    if (isJitCall) {
+      masm.alignJitStackBasedOnNArgs(countReg, /*countIncludesThis = */ true);
+    }
+
+    // Push all values, starting at the last one.
+    Label loop, done;
+    masm.branchTest32(Assembler::Zero, countReg, countReg, &done);
+    masm.bind(&loop);
+    {
+      masm.pushValue(Address(argPtr, 0));
+      masm.addPtr(Imm32(sizeof(Value)), argPtr);
+
+      masm.branchSub32(Assembler::NonZero, Imm32(1), countReg, &loop);
+    }
+    masm.bind(&done);
+  }
+}
+
+void BaselineCacheIRCompiler::pushArrayArguments(Register argcReg,
+                                                 Register scratch,
+                                                 Register scratch2,
+                                                 bool isJitCall,
+                                                 bool isConstructing) {
+  MOZ_ASSERT(enteredStubFrame_);
+
+  // Pull the array off the stack before aligning.
+  Register startReg = scratch;
+  size_t arrayOffset =
+      (isConstructing * sizeof(Value)) + BaselineStubFrameLayout::Size();
+  masm.unboxObject(Address(FramePointer, arrayOffset), startReg);
+  masm.loadPtr(Address(startReg, NativeObject::offsetOfElements()), startReg);
+
+  // Align the stack such that the JitFrameLayout is aligned on the
+  // JitStackAlignment.
+  if (isJitCall) {
+    Register alignReg = argcReg;
+    if (isConstructing) {
+      // If we are constructing, we must take newTarget into account.
+      alignReg = scratch2;
+      masm.computeEffectiveAddress(Address(argcReg, 1), alignReg);
+    }
+    masm.alignJitStackBasedOnNArgs(alignReg, /*countIncludesThis =*/false);
+  }
+
+  // Push newTarget, if necessary
+  if (isConstructing) {
+    masm.pushValue(Address(FramePointer, BaselineStubFrameLayout::Size()));
+  }
+
+  // Push arguments: set up endReg to point to &array[argc]
+  Register endReg = scratch2;
+  BaseValueIndex endAddr(startReg, argcReg);
+  masm.computeEffectiveAddress(endAddr, endReg);
+
+  // Copying pre-decrements endReg by 8 until startReg is reached
+  Label copyDone;
+  Label copyStart;
+  masm.bind(&copyStart);
+  masm.branchPtr(Assembler::Equal, endReg, startReg, &copyDone);
+  masm.subPtr(Imm32(sizeof(Value)), endReg);
+  masm.pushValue(Address(endReg, 0));
+  masm.jump(&copyStart);
+  masm.bind(&copyDone);
+
+  // Push |this|.
+  size_t thisvOffset =
+      BaselineStubFrameLayout::Size() + (1 + isConstructing) * sizeof(Value);
+  masm.pushValue(Address(FramePointer, thisvOffset));
+
+  // Push |callee| if needed.
+  if (!isJitCall) {
+    size_t calleeOffset =
+        BaselineStubFrameLayout::Size() + (2 + isConstructing) * sizeof(Value);
+    masm.pushValue(Address(FramePointer, calleeOffset));
+  }
+}
+
+void BaselineCacheIRCompiler::pushFunApplyNullUndefinedArguments(
+    Register calleeReg, bool isJitCall) {
+  // argc is already set to 0, so we just have to push |this| and (for native
+  // calls) the callee.
+
+  MOZ_ASSERT(enteredStubFrame_);
+
+  // Align the stack such that the JitFrameLayout is aligned on the
+  // JitStackAlignment.
+  if (isJitCall) {
+    masm.alignJitStackBasedOnNArgs(0, /*countIncludesThis =*/false);
+  }
+
+  // Push |this|.
+  size_t thisvOffset = BaselineStubFrameLayout::Size() + 1 * sizeof(Value);
+  masm.pushValue(Address(FramePointer, thisvOffset));
+
+  // Push |callee| if needed.
+  if (!isJitCall) {
+    masm.Push(TypedOrValueRegister(MIRType::Object, AnyRegister(calleeReg)));
+  }
+}
+
+void BaselineCacheIRCompiler::pushFunCallArguments(
+    Register argcReg, Register calleeReg, Register scratch, Register scratch2,
+    uint32_t argcFixed, bool isJitCall) {
+  if (argcFixed == 0) {
+    if (isJitCall) {
+      // Align the stack to 0 args.
+      masm.alignJitStackBasedOnNArgs(0, /*countIncludesThis = */ false);
+    }
+
+    // Store the new |this|.
+    masm.pushValue(UndefinedValue());
+
+    // Store |callee| if needed.
+    if (!isJitCall) {
+      masm.Push(TypedOrValueRegister(MIRType::Object, AnyRegister(calleeReg)));
+    }
+  } else if (argcFixed < MaxUnrolledArgCopy) {
+    // See below for why we subtract 1 from argcFixed.
+    argcFixed -= 1;
+    masm.sub32(Imm32(1), argcReg);
+    pushStandardArguments(argcReg, scratch, scratch2, argcFixed, isJitCall,
+                          /*isConstructing =*/false);
+  } else {
+    Label zeroArgs, done;
+    masm.branchTest32(Assembler::Zero, argcReg, argcReg, &zeroArgs);
+
+    // When we call fun_call, the stack looks like the left column (note
+    // that newTarget will not be present, because fun_call cannot be a
+    // constructor call):
+    //
+    // ***Arguments to fun_call***
+    // callee (fun_call)               ***Arguments to target***
+    // this (target function)   -----> callee
+    // arg0 (this of target)    -----> this
+    // arg1 (arg0 of target)    -----> arg0
+    // argN (argN-1 of target)  -----> arg1
+    //
+    // As demonstrated in the right column, this is exactly what we need
+    // the stack to look like when calling pushStandardArguments for target,
+    // except with one more argument. If we subtract 1 from argc,
+    // everything works out correctly.
+    masm.sub32(Imm32(1), argcReg);
+
+    pushStandardArguments(argcReg, scratch, scratch2, argcFixed, isJitCall,
+                          /*isConstructing =*/false);
+
+    masm.jump(&done);
+    masm.bind(&zeroArgs);
+
+    // The exception is the case where argc == 0:
+    //
+    // ***Arguments to fun_call***
+    // callee (fun_call)               ***Arguments to target***
+    // this (target function)   -----> callee
+    // <nothing>                -----> this
+    //
+    // In this case, we push |undefined| for |this|.
+
+    if (isJitCall) {
+      // Align the stack to 0 args.
+      masm.alignJitStackBasedOnNArgs(0, /*countIncludesThis = */ false);
+    }
+
+    // Store the new |this|.
+    masm.pushValue(UndefinedValue());
+
+    // Store |callee| if needed.
+    if (!isJitCall) {
+      masm.Push(TypedOrValueRegister(MIRType::Object, AnyRegister(calleeReg)));
+    }
+
+    masm.bind(&done);
+  }
+}
+
+void BaselineCacheIRCompiler::pushFunApplyArgsObj(Register argcReg,
+                                                  Register calleeReg,
+                                                  Register scratch,
+                                                  Register scratch2,
+                                                  bool isJitCall) {
+  MOZ_ASSERT(enteredStubFrame_);
+
+  // Load the arguments object off the stack before aligning.
+  Register argsReg = scratch;
+  masm.unboxObject(Address(FramePointer, BaselineStubFrameLayout::Size()),
+                   argsReg);
+
+  // Align the stack such that the JitFrameLayout is aligned on the
+  // JitStackAlignment.
+  if (isJitCall) {
+    masm.alignJitStackBasedOnNArgs(argcReg, /*countIncludesThis =*/false);
+  }
+
+  // Load ArgumentsData.
+  masm.loadPrivate(Address(argsReg, ArgumentsObject::getDataSlotOffset()),
+                   argsReg);
+
+  // We push the arguments onto the stack last-to-first.
+  // Compute the bounds of the arguments array.
+  Register currReg = scratch2;
+  Address argsStartAddr(argsReg, ArgumentsData::offsetOfArgs());
+  masm.computeEffectiveAddress(argsStartAddr, argsReg);
+  BaseValueIndex argsEndAddr(argsReg, argcReg);
+  masm.computeEffectiveAddress(argsEndAddr, currReg);
+
+  // Loop until all arguments have been pushed.
+  Label done, loop;
+  masm.bind(&loop);
+  masm.branchPtr(Assembler::Equal, currReg, argsReg, &done);
+  masm.subPtr(Imm32(sizeof(Value)), currReg);
+
+  Address currArgAddr(currReg, 0);
+#ifdef DEBUG
+  // Arguments are forwarded to the call object if they are closed over.
+  // In this case, OVERRIDDEN_ELEMENTS_BIT should be set.
+  Label notForwarded;
+  masm.branchTestMagic(Assembler::NotEqual, currArgAddr, &notForwarded);
+  masm.assumeUnreachable("Should have checked for overridden elements");
+  masm.bind(&notForwarded);
+#endif
+  masm.pushValue(currArgAddr);
+
+  masm.jump(&loop);
+  masm.bind(&done);
+
+  // Push arg0 as |this| for call
+  masm.pushValue(
+      Address(FramePointer, BaselineStubFrameLayout::Size() + sizeof(Value)));
+
+  // Push |callee| if needed.
+  if (!isJitCall) {
+    masm.Push(TypedOrValueRegister(MIRType::Object, AnyRegister(calleeReg)));
+  }
+}
+
+void BaselineCacheIRCompiler::pushBoundFunctionArguments(
+    Register argcReg, Register calleeReg, Register scratch, Register scratch2,
+    CallFlags flags, uint32_t numBoundArgs, bool isJitCall) {
+  bool isConstructing = flags.isConstructing();
+  uint32_t additionalArgc = 1 + isConstructing;  // |this| and newTarget
+
+  // Calculate total number of Values to push.
+  Register countReg = scratch;
+  masm.computeEffectiveAddress(Address(argcReg, numBoundArgs + additionalArgc),
+                               countReg);
+
+  // Align the stack such that the JitFrameLayout is aligned on the
+  // JitStackAlignment.
+  if (isJitCall) {
+    masm.alignJitStackBasedOnNArgs(countReg, /*countIncludesThis = */ true);
+  }
+
+  if (isConstructing) {
+    // Push the bound function's target as newTarget.
+    Address boundTarget(calleeReg, BoundFunctionObject::offsetOfTargetSlot());
+    masm.pushValue(boundTarget);
+  }
+
+  // Ensure argPtr initially points to the last argument. Skip the stub frame.
+  Register argPtr = scratch2;
+  Address argAddress(FramePointer, BaselineStubFrameLayout::Size());
+  if (isConstructing) {
+    // Skip newTarget.
+    argAddress.offset += sizeof(Value);
+  }
+  masm.computeEffectiveAddress(argAddress, argPtr);
+
+  // Push all supplied arguments, starting at the last one.
+  Label loop, done;
+  masm.branchTest32(Assembler::Zero, argcReg, argcReg, &done);
+  masm.move32(argcReg, countReg);
+  masm.bind(&loop);
+  {
+    masm.pushValue(Address(argPtr, 0));
+    masm.addPtr(Imm32(sizeof(Value)), argPtr);
+
+    masm.branchSub32(Assembler::NonZero, Imm32(1), countReg, &loop);
+  }
+  masm.bind(&done);
+
+  // Push the bound arguments, starting at the last one.
+  constexpr size_t inlineArgsOffset =
+      BoundFunctionObject::offsetOfFirstInlineBoundArg();
+  if (numBoundArgs <= BoundFunctionObject::MaxInlineBoundArgs) {
+    for (size_t i = 0; i < numBoundArgs; i++) {
+      size_t argIndex = numBoundArgs - i - 1;
+      Address argAddr(calleeReg, inlineArgsOffset + argIndex * sizeof(Value));
+      masm.pushValue(argAddr);
+    }
+  } else {
+    masm.unboxObject(Address(calleeReg, inlineArgsOffset), scratch);
+    masm.loadPtr(Address(scratch, NativeObject::offsetOfElements()), scratch);
+    for (size_t i = 0; i < numBoundArgs; i++) {
+      size_t argIndex = numBoundArgs - i - 1;
+      Address argAddr(scratch, argIndex * sizeof(Value));
+      masm.pushValue(argAddr);
+    }
+  }
+
+  if (isConstructing) {
+    // Push the |this| Value. This is either the object we allocated or the
+    // JS_UNINITIALIZED_LEXICAL magic value. It's stored in the BaselineFrame,
+    // so skip past the stub frame, (unbound) arguments and newTarget.
+    BaseValueIndex thisAddress(FramePointer, argcReg,
+                               BaselineStubFrameLayout::Size() + sizeof(Value));
+    masm.pushValue(thisAddress, scratch);
+  } else {
+    // Push the bound |this|.
+    Address boundThis(calleeReg, BoundFunctionObject::offsetOfBoundThisSlot());
+    masm.pushValue(boundThis);
+  }
+}
+
+bool BaselineCacheIRCompiler::emitCallNativeShared(
+    NativeCallType callType, ObjOperandId calleeId, Int32OperandId argcId,
+    CallFlags flags, uint32_t argcFixed, Maybe<bool> ignoresReturnValue,
+    Maybe<uint32_t> targetOffset) {
+  AutoOutputRegister output(*this);
+  AutoScratchRegisterMaybeOutput scratch(allocator, masm, output);
+  AutoScratchRegister scratch2(allocator, masm);
+
+  Register calleeReg = allocator.useRegister(masm, calleeId);
+  Register argcReg = allocator.useRegister(masm, argcId);
+
+  bool isConstructing = flags.isConstructing();
+  bool isSameRealm = flags.isSameRealm();
+
+  if (!updateArgc(flags, argcReg, scratch)) {
+    return false;
+  }
+
+  allocator.discardStack(masm);
+
+  // Push a stub frame so that we can perform a non-tail call.
+  // Note that this leaves the return address in TailCallReg.
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  if (!isSameRealm) {
+    masm.switchToObjectRealm(calleeReg, scratch);
+  }
+
+  pushArguments(argcReg, calleeReg, scratch, scratch2, flags, argcFixed,
+                /*isJitCall =*/false);
+
+  // Native functions have the signature:
+  //
+  //    bool (*)(JSContext*, unsigned, Value* vp)
+  //
+  // Where vp[0] is space for callee/return value, vp[1] is |this|, and vp[2]
+  // onward are the function arguments.
+
+  // Initialize vp.
+  masm.moveStackPtrTo(scratch2.get());
+
+  // Construct a native exit frame.
+  masm.push(argcReg);
+
+  masm.pushFrameDescriptor(FrameType::BaselineStub);
+  masm.push(ICTailCallReg);
+  masm.push(FramePointer);
+  masm.loadJSContext(scratch);
+  masm.enterFakeExitFrameForNative(scratch, scratch, isConstructing);
+
+  // Execute call.
+  masm.setupUnalignedABICall(scratch);
+  masm.loadJSContext(scratch);
+  masm.passABIArg(scratch);
+  masm.passABIArg(argcReg);
+  masm.passABIArg(scratch2);
+
+  switch (callType) {
+    case NativeCallType::Native: {
+#ifdef JS_SIMULATOR
+      // The simulator requires VM calls to be redirected to a special
+      // swi instruction to handle them, so we store the redirected
+      // pointer in the stub and use that instead of the original one.
+      // (See CacheIRWriter::callNativeFunction.)
+      Address redirectedAddr(stubAddress(*targetOffset));
+      masm.callWithABI(redirectedAddr);
+#else
+      if (*ignoresReturnValue) {
+        masm.loadPrivate(
+            Address(calleeReg, JSFunction::offsetOfJitInfoOrScript()),
+            calleeReg);
+        masm.callWithABI(
+            Address(calleeReg, JSJitInfo::offsetOfIgnoresReturnValueNative()));
+      } else {
+        // This depends on the native function pointer being stored unchanged as
+        // a PrivateValue.
+        masm.callWithABI(Address(calleeReg, JSFunction::offsetOfNativeOrEnv()));
+      }
+#endif
+    } break;
+    case NativeCallType::ClassHook: {
+      Address nativeAddr(stubAddress(*targetOffset));
+      masm.callWithABI(nativeAddr);
+    } break;
+  }
+
+  // Test for failure.
+  masm.branchIfFalseBool(ReturnReg, masm.exceptionLabel());
+
+  // Load the return value.
+  masm.loadValue(
+      Address(masm.getStackPointer(), NativeExitFrameLayout::offsetOfResult()),
+      output.valueReg());
+
+  stubFrame.leave(masm);
+
+  if (!isSameRealm) {
+    masm.switchToBaselineFrameRealm(scratch2);
+  }
+
+  return true;
+}
+
+#ifdef JS_SIMULATOR
+bool BaselineCacheIRCompiler::emitCallNativeFunction(ObjOperandId calleeId,
+                                                     Int32OperandId argcId,
+                                                     CallFlags flags,
+                                                     uint32_t argcFixed,
+                                                     uint32_t targetOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Maybe<bool> ignoresReturnValue;
+  Maybe<uint32_t> targetOffset_ = mozilla::Some(targetOffset);
+  return emitCallNativeShared(NativeCallType::Native, calleeId, argcId, flags,
+                              argcFixed, ignoresReturnValue, targetOffset_);
+}
+
+bool BaselineCacheIRCompiler::emitCallDOMFunction(
+    ObjOperandId calleeId, Int32OperandId argcId, ObjOperandId thisObjId,
+    CallFlags flags, uint32_t argcFixed, uint32_t targetOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Maybe<bool> ignoresReturnValue;
+  Maybe<uint32_t> targetOffset_ = mozilla::Some(targetOffset);
+  return emitCallNativeShared(NativeCallType::Native, calleeId, argcId, flags,
+                              argcFixed, ignoresReturnValue, targetOffset_);
+}
+#else
+bool BaselineCacheIRCompiler::emitCallNativeFunction(ObjOperandId calleeId,
+                                                     Int32OperandId argcId,
+                                                     CallFlags flags,
+                                                     uint32_t argcFixed,
+                                                     bool ignoresReturnValue) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Maybe<bool> ignoresReturnValue_ = mozilla::Some(ignoresReturnValue);
+  Maybe<uint32_t> targetOffset;
+  return emitCallNativeShared(NativeCallType::Native, calleeId, argcId, flags,
+                              argcFixed, ignoresReturnValue_, targetOffset);
+}
+
+bool BaselineCacheIRCompiler::emitCallDOMFunction(ObjOperandId calleeId,
+                                                  Int32OperandId argcId,
+                                                  ObjOperandId thisObjId,
+                                                  CallFlags flags,
+                                                  uint32_t argcFixed) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Maybe<bool> ignoresReturnValue = mozilla::Some(false);
+  Maybe<uint32_t> targetOffset;
+  return emitCallNativeShared(NativeCallType::Native, calleeId, argcId, flags,
+                              argcFixed, ignoresReturnValue, targetOffset);
+}
+#endif
+
+bool BaselineCacheIRCompiler::emitCallClassHook(ObjOperandId calleeId,
+                                                Int32OperandId argcId,
+                                                CallFlags flags,
+                                                uint32_t argcFixed,
+                                                uint32_t targetOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Maybe<bool> ignoresReturnValue;
+  Maybe<uint32_t> targetOffset_ = mozilla::Some(targetOffset);
+  return emitCallNativeShared(NativeCallType::ClassHook, calleeId, argcId,
+                              flags, argcFixed, ignoresReturnValue,
+                              targetOffset_);
+}
+
+// Helper function for loading call arguments from the stack.  Loads
+// and unboxes an object from a specific slot.
+void BaselineCacheIRCompiler::loadStackObject(ArgumentKind kind,
+                                              CallFlags flags, Register argcReg,
+                                              Register dest) {
+  MOZ_ASSERT(enteredStubFrame_);
+
+  bool addArgc = false;
+  int32_t slotIndex = GetIndexOfArgument(kind, flags, &addArgc);
+
+  if (addArgc) {
+    int32_t slotOffset =
+        slotIndex * sizeof(JS::Value) + BaselineStubFrameLayout::Size();
+    BaseValueIndex slotAddr(FramePointer, argcReg, slotOffset);
+    masm.unboxObject(slotAddr, dest);
+  } else {
+    int32_t slotOffset =
+        slotIndex * sizeof(JS::Value) + BaselineStubFrameLayout::Size();
+    Address slotAddr(FramePointer, slotOffset);
+    masm.unboxObject(slotAddr, dest);
+  }
+}
+
+template <typename T>
+void BaselineCacheIRCompiler::storeThis(const T& newThis, Register argcReg,
+                                        CallFlags flags) {
+  switch (flags.getArgFormat()) {
+    case CallFlags::Standard: {
+      BaseValueIndex thisAddress(
+          FramePointer,
+          argcReg,                               // Arguments
+          1 * sizeof(Value) +                    // NewTarget
+              BaselineStubFrameLayout::Size());  // Stub frame
+      masm.storeValue(newThis, thisAddress);
+    } break;
+    case CallFlags::Spread: {
+      Address thisAddress(FramePointer,
+                          2 * sizeof(Value) +  // Arg array, NewTarget
+                              BaselineStubFrameLayout::Size());  // Stub frame
+      masm.storeValue(newThis, thisAddress);
+    } break;
+    default:
+      MOZ_CRASH("Invalid arg format for scripted constructor");
+  }
+}
+
+/*
+ * Scripted constructors require a |this| object to be created prior to the
+ * call. When this function is called, the stack looks like (bottom->top):
+ *
+ * [..., Callee, ThisV, Arg0V, ..., ArgNV, NewTarget, StubFrameHeader]
+ *
+ * At this point, |ThisV| is JSWhyMagic::JS_IS_CONSTRUCTING.
+ *
+ * This function calls CreateThis to generate a new |this| object, then
+ * overwrites the magic ThisV on the stack.
+ */
+void BaselineCacheIRCompiler::createThis(Register argcReg, Register calleeReg,
+                                         Register scratch, CallFlags flags,
+                                         bool isBoundFunction) {
+  MOZ_ASSERT(flags.isConstructing());
+
+  if (flags.needsUninitializedThis()) {
+    storeThis(MagicValue(JS_UNINITIALIZED_LEXICAL), argcReg, flags);
+    return;
+  }
+
+  // Save live registers that don't have to be traced.
+  LiveGeneralRegisterSet liveNonGCRegs;
+  liveNonGCRegs.add(argcReg);
+  masm.PushRegsInMask(liveNonGCRegs);
+
+  // CreateThis takes two arguments: callee, and newTarget.
+
+  if (isBoundFunction) {
+    // Push the bound function's target as callee and newTarget.
+    Address boundTarget(calleeReg, BoundFunctionObject::offsetOfTargetSlot());
+    masm.unboxObject(boundTarget, scratch);
+    masm.push(scratch);
+    masm.push(scratch);
+  } else {
+    // Push newTarget:
+    loadStackObject(ArgumentKind::NewTarget, flags, argcReg, scratch);
+    masm.push(scratch);
+
+    // Push callee:
+    loadStackObject(ArgumentKind::Callee, flags, argcReg, scratch);
+    masm.push(scratch);
+  }
+
+  // Call CreateThisFromIC.
+  using Fn =
+      bool (*)(JSContext*, HandleObject, HandleObject, MutableHandleValue);
+  callVM<Fn, CreateThisFromIC>(masm);
+
+#ifdef DEBUG
+  Label createdThisOK;
+  masm.branchTestObject(Assembler::Equal, JSReturnOperand, &createdThisOK);
+  masm.branchTestMagic(Assembler::Equal, JSReturnOperand, &createdThisOK);
+  masm.assumeUnreachable(
+      "The return of CreateThis must be an object or uninitialized.");
+  masm.bind(&createdThisOK);
+#endif
+
+  // Restore saved registers.
+  masm.PopRegsInMask(liveNonGCRegs);
+  Address stubAddr(FramePointer, BaselineStubFrameLayout::ICStubOffsetFromFP);
+  masm.loadPtr(stubAddr, ICStubReg);
+
+  // Save |this| value back into pushed arguments on stack.
+  MOZ_ASSERT(!liveNonGCRegs.aliases(JSReturnOperand));
+  storeThis(JSReturnOperand, argcReg, flags);
+
+  // Restore calleeReg. CreateThisFromIC may trigger a GC, so we reload the
+  // callee from the stub frame (which is traced) instead of spilling it to
+  // the stack.
+  loadStackObject(ArgumentKind::Callee, flags, argcReg, calleeReg);
+}
+
+void BaselineCacheIRCompiler::updateReturnValue() {
+  Label skipThisReplace;
+  masm.branchTestObject(Assembler::Equal, JSReturnOperand, &skipThisReplace);
+
+  // If a constructor does not explicitly return an object, the return value
+  // of the constructor is |this|. We load it out of the baseline stub frame.
+
+  // At this point, the stack looks like this:
+  //  newTarget
+  //  ArgN
+  //  ...
+  //  Arg0
+  //  ThisVal         <---- We want this value.
+  //  Callee token          | Skip two stack slots.
+  //  Frame descriptor      v
+  //  [Top of stack]
+  size_t thisvOffset =
+      JitFrameLayout::offsetOfThis() - JitFrameLayout::bytesPoppedAfterCall();
+  Address thisAddress(masm.getStackPointer(), thisvOffset);
+  masm.loadValue(thisAddress, JSReturnOperand);
+
+#ifdef DEBUG
+  masm.branchTestObject(Assembler::Equal, JSReturnOperand, &skipThisReplace);
+  masm.assumeUnreachable("Return of constructing call should be an object.");
+#endif
+  masm.bind(&skipThisReplace);
+}
+
+bool BaselineCacheIRCompiler::emitCallScriptedFunction(ObjOperandId calleeId,
+                                                       Int32OperandId argcId,
+                                                       CallFlags flags,
+                                                       uint32_t argcFixed) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  AutoOutputRegister output(*this);
+  AutoScratchRegisterMaybeOutput scratch(allocator, masm, output);
+  AutoScratchRegister scratch2(allocator, masm);
+
+  Register calleeReg = allocator.useRegister(masm, calleeId);
+  Register argcReg = allocator.useRegister(masm, argcId);
+
+  bool isConstructing = flags.isConstructing();
+  bool isSameRealm = flags.isSameRealm();
+
+  if (!updateArgc(flags, argcReg, scratch)) {
+    return false;
+  }
+
+  allocator.discardStack(masm);
+
+  // Push a stub frame so that we can perform a non-tail call.
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  if (!isSameRealm) {
+    masm.switchToObjectRealm(calleeReg, scratch);
+  }
+
+  if (isConstructing) {
+    createThis(argcReg, calleeReg, scratch, flags,
+               /* isBoundFunction = */ false);
+  }
+
+  pushArguments(argcReg, calleeReg, scratch, scratch2, flags, argcFixed,
+                /*isJitCall =*/true);
+
+  // Load the start of the target JitCode.
+  Register code = scratch2;
+  masm.loadJitCodeRaw(calleeReg, code);
+
+  // Note that we use Push, not push, so that callJit will align the stack
+  // properly on ARM.
+  masm.PushCalleeToken(calleeReg, isConstructing);
+  masm.PushFrameDescriptorForJitCall(FrameType::BaselineStub, argcReg, scratch);
+
+  // Handle arguments underflow.
+  Label noUnderflow;
+  masm.loadFunctionArgCount(calleeReg, calleeReg);
+  masm.branch32(Assembler::AboveOrEqual, argcReg, calleeReg, &noUnderflow);
+  {
+    // Call the arguments rectifier.
+    TrampolinePtr argumentsRectifier =
+        cx_->runtime()->jitRuntime()->getArgumentsRectifier();
+    masm.movePtr(argumentsRectifier, code);
+  }
+
+  masm.bind(&noUnderflow);
+  masm.callJit(code);
+
+  // If this is a constructing call, and the callee returns a non-object,
+  // replace it with the |this| object passed in.
+  if (isConstructing) {
+    updateReturnValue();
+  }
+
+  stubFrame.leave(masm);
+
+  if (!isSameRealm) {
+    masm.switchToBaselineFrameRealm(scratch2);
+  }
+
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitCallWasmFunction(
+    ObjOperandId calleeId, Int32OperandId argcId, CallFlags flags,
+    uint32_t argcFixed, uint32_t funcExportOffset, uint32_t instanceOffset) {
+  return emitCallScriptedFunction(calleeId, argcId, flags, argcFixed);
+}
+
+bool BaselineCacheIRCompiler::emitCallInlinedFunction(ObjOperandId calleeId,
+                                                      Int32OperandId argcId,
+                                                      uint32_t icScriptOffset,
+                                                      CallFlags flags,
+                                                      uint32_t argcFixed) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  AutoOutputRegister output(*this);
+  AutoScratchRegisterMaybeOutput scratch(allocator, masm, output);
+  AutoScratchRegisterMaybeOutputType scratch2(allocator, masm, output);
+  AutoScratchRegister codeReg(allocator, masm);
+
+  Register calleeReg = allocator.useRegister(masm, calleeId);
+  Register argcReg = allocator.useRegister(masm, argcId);
+
+  bool isConstructing = flags.isConstructing();
+  bool isSameRealm = flags.isSameRealm();
+
+  FailurePath* failure;
+  if (!addFailurePath(&failure)) {
+    return false;
+  }
+
+  masm.loadBaselineJitCodeRaw(calleeReg, codeReg, failure->label());
+
+  if (!updateArgc(flags, argcReg, scratch)) {
+    return false;
+  }
+
+  allocator.discardStack(masm);
+
+  // Push a stub frame so that we can perform a non-tail call.
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  if (!isSameRealm) {
+    masm.switchToObjectRealm(calleeReg, scratch);
+  }
+
+  Label baselineScriptDiscarded;
+  if (isConstructing) {
+    createThis(argcReg, calleeReg, scratch, flags,
+               /* isBoundFunction = */ false);
+
+    // CreateThisFromIC may trigger a GC and discard the BaselineScript.
+    // We have already called discardStack, so we can't use a FailurePath.
+    // Instead, we skip storing the ICScript in the JSContext and use a
+    // normal non-inlined call.
+    masm.loadBaselineJitCodeRaw(calleeReg, codeReg, &baselineScriptDiscarded);
+  }
+
+  // Store icScript in the context.
+  Address icScriptAddr(stubAddress(icScriptOffset));
+  masm.loadPtr(icScriptAddr, scratch);
+  masm.storeICScriptInJSContext(scratch);
+
+  if (isConstructing) {
+    Label skip;
+    masm.jump(&skip);
+    masm.bind(&baselineScriptDiscarded);
+    masm.loadJitCodeRaw(calleeReg, codeReg);
+    masm.bind(&skip);
+  }
+
+  pushArguments(argcReg, calleeReg, scratch, scratch2, flags, argcFixed,
+                /*isJitCall =*/true);
+
+  // Note that we use Push, not push, so that callJit will align the stack
+  // properly on ARM.
+  masm.PushCalleeToken(calleeReg, isConstructing);
+  masm.PushFrameDescriptorForJitCall(FrameType::BaselineStub, argcReg, scratch);
+
+  // Handle arguments underflow.
+  Label noUnderflow;
+  masm.loadFunctionArgCount(calleeReg, calleeReg);
+  masm.branch32(Assembler::AboveOrEqual, argcReg, calleeReg, &noUnderflow);
+
+  // Call the trial-inlining arguments rectifier.
+  ArgumentsRectifierKind kind = ArgumentsRectifierKind::TrialInlining;
+  TrampolinePtr argumentsRectifier =
+      cx_->runtime()->jitRuntime()->getArgumentsRectifier(kind);
+  masm.movePtr(argumentsRectifier, codeReg);
+
+  masm.bind(&noUnderflow);
+  masm.callJit(codeReg);
+
+  // If this is a constructing call, and the callee returns a non-object,
+  // replace it with the |this| object passed in.
+  if (isConstructing) {
+    updateReturnValue();
+  }
+
+  stubFrame.leave(masm);
+
+  if (!isSameRealm) {
+    masm.switchToBaselineFrameRealm(codeReg);
+  }
+
+  return true;
+}
+
+#ifdef JS_PUNBOX64
+template <typename IdType>
+bool BaselineCacheIRCompiler::emitCallScriptedProxyGetShared(
+    ValOperandId targetId, ObjOperandId receiverId, ObjOperandId handlerId,
+    uint32_t trapOffset, IdType id, uint32_t nargsAndFlags) {
+  Address trapAddr(stubAddress(trapOffset));
+  Register handler = allocator.useRegister(masm, handlerId);
+  ValueOperand target = allocator.useValueRegister(masm, targetId);
+  Register receiver = allocator.useRegister(masm, receiverId);
+  ValueOperand idVal;
+  if constexpr (std::is_same_v<IdType, ValOperandId>) {
+    idVal = allocator.useValueRegister(masm, id);
+  }
+
+  AutoScratchRegister code(allocator, masm);
+  AutoScratchRegister callee(allocator, masm);
+  AutoScratchRegister scratch(allocator, masm);
+  ValueOperand scratchVal(scratch);
+
+  masm.loadPtr(trapAddr, callee);
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  // We need to keep the target around to potentially validate the proxy result
+  stubFrame.storeTracedValue(masm, target);
+  if constexpr (std::is_same_v<IdType, ValOperandId>) {
+    stubFrame.storeTracedValue(masm, idVal);
+  } else {
+    // We need to either trace the id here or grab the ICStubReg back from
+    // FramePointer + sizeof(void*) after the call in order to load it again.
+    // We elect to do this because it unifies the code path after the call.
+    Address idAddr(stubAddress(id));
+    masm.loadPtr(idAddr, scratch);
+    masm.tagValue(JSVAL_TYPE_STRING, scratch, scratchVal);
+    stubFrame.storeTracedValue(masm, scratchVal);
+  }
+
+  uint16_t nargs = nargsAndFlags >> JSFunction::ArgCountShift;
+  masm.alignJitStackBasedOnNArgs(std::max(uint16_t(3), nargs),
+                                 /*countIncludesThis = */ false);
+  for (size_t i = 3; i < nargs; i++) {
+    masm.Push(UndefinedValue());
+  }
+
+  masm.tagValue(JSVAL_TYPE_OBJECT, receiver, scratchVal);
+  masm.Push(scratchVal);
+
+  if constexpr (std::is_same_v<IdType, ValOperandId>) {
+    masm.Push(idVal);
+  } else {
+    stubFrame.loadTracedValue(masm, 1, scratchVal);
+    masm.Push(scratchVal);
+  }
+
+  masm.Push(target);
+
+  masm.tagValue(JSVAL_TYPE_OBJECT, handler, scratchVal);
+  masm.Push(scratchVal);
+
+  masm.loadJitCodeRaw(callee, code);
+
+  masm.Push(callee);
+  masm.PushFrameDescriptorForJitCall(FrameType::BaselineStub, 3);
+
+  masm.callJit(code);
+
+  Register scratch2 = code;
+
+  Label success;
+  stubFrame.loadTracedValue(masm, 0, scratchVal);
+  masm.unboxObject(scratchVal, scratch);
+  masm.branchTestObjectNeedsProxyResultValidation(Assembler::Zero, scratch,
+                                                  scratch2, &success);
+  ValueOperand scratchVal2(scratch2);
+  stubFrame.loadTracedValue(masm, 1, scratchVal2);
+  masm.Push(JSReturnOperand);
+  masm.Push(scratchVal2);
+  masm.Push(scratch);
+  using Fn = bool (*)(JSContext*, HandleObject, HandleValue, HandleValue,
+                      MutableHandleValue);
+  callVM<Fn, CheckProxyGetByValueResult>(masm);
+
+  masm.bind(&success);
+
+  stubFrame.leave(masm);
+
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitCallScriptedProxyGetResult(
+    ValOperandId targetId, ObjOperandId receiverId, ObjOperandId handlerId,
+    uint32_t trapOffset, uint32_t idOffset, uint32_t nargsAndFlags) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  return emitCallScriptedProxyGetShared(targetId, receiverId, handlerId,
+                                        trapOffset, idOffset, nargsAndFlags);
+}
+
+bool BaselineCacheIRCompiler::emitCallScriptedProxyGetByValueResult(
+    ValOperandId targetId, ObjOperandId receiverId, ObjOperandId handlerId,
+    ValOperandId idId, uint32_t trapOffset, uint32_t nargsAndFlags) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  return emitCallScriptedProxyGetShared(targetId, receiverId, handlerId,
+                                        trapOffset, idId, nargsAndFlags);
+}
+#endif
+
+bool BaselineCacheIRCompiler::emitCallBoundScriptedFunction(
+    ObjOperandId calleeId, ObjOperandId targetId, Int32OperandId argcId,
+    CallFlags flags, uint32_t numBoundArgs) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  AutoScratchRegisterMaybeOutput scratch(allocator, masm, output);
+  AutoScratchRegister scratch2(allocator, masm);
+
+  Register calleeReg = allocator.useRegister(masm, calleeId);
+  Register argcReg = allocator.useRegister(masm, argcId);
+
+  bool isConstructing = flags.isConstructing();
+  bool isSameRealm = flags.isSameRealm();
+
+  allocator.discardStack(masm);
+
+  // Push a stub frame so that we can perform a non-tail call.
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  Address boundTarget(calleeReg, BoundFunctionObject::offsetOfTargetSlot());
+
+  // If we're constructing, switch to the target's realm and create |this|. If
+  // we're not constructing, we switch to the target's realm after pushing the
+  // arguments and loading the target.
+  if (isConstructing) {
+    if (!isSameRealm) {
+      masm.unboxObject(boundTarget, scratch);
+      masm.switchToObjectRealm(scratch, scratch);
+    }
+    createThis(argcReg, calleeReg, scratch, flags,
+               /* isBoundFunction = */ true);
+  }
+
+  // Push all arguments, including |this|.
+  pushBoundFunctionArguments(argcReg, calleeReg, scratch, scratch2, flags,
+                             numBoundArgs, /* isJitCall = */ true);
+
+  // Load the target JSFunction.
+  masm.unboxObject(boundTarget, calleeReg);
+
+  if (!isConstructing && !isSameRealm) {
+    masm.switchToObjectRealm(calleeReg, scratch);
+  }
+
+  // Update argc.
+  masm.add32(Imm32(numBoundArgs), argcReg);
+
+  // Load the start of the target JitCode.
+  Register code = scratch2;
+  masm.loadJitCodeRaw(calleeReg, code);
+
+  // Note that we use Push, not push, so that callJit will align the stack
+  // properly on ARM.
+  masm.PushCalleeToken(calleeReg, isConstructing);
+  masm.PushFrameDescriptorForJitCall(FrameType::BaselineStub, argcReg, scratch);
+
+  // Handle arguments underflow.
+  Label noUnderflow;
+  masm.loadFunctionArgCount(calleeReg, calleeReg);
+  masm.branch32(Assembler::AboveOrEqual, argcReg, calleeReg, &noUnderflow);
+  {
+    // Call the arguments rectifier.
+    TrampolinePtr argumentsRectifier =
+        cx_->runtime()->jitRuntime()->getArgumentsRectifier();
+    masm.movePtr(argumentsRectifier, code);
+  }
+
+  masm.bind(&noUnderflow);
+  masm.callJit(code);
+
+  if (isConstructing) {
+    updateReturnValue();
+  }
+
+  stubFrame.leave(masm);
+
+  if (!isSameRealm) {
+    masm.switchToBaselineFrameRealm(scratch2);
+  }
+
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitNewArrayObjectResult(uint32_t arrayLength,
+                                                       uint32_t shapeOffset,
+                                                       uint32_t siteOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  gc::AllocKind allocKind = GuessArrayGCKind(arrayLength);
+  MOZ_ASSERT(CanChangeToBackgroundAllocKind(allocKind, &ArrayObject::class_));
+  allocKind = ForegroundToBackgroundAllocKind(allocKind);
+
+  uint32_t slotCount = GetGCKindSlots(allocKind);
+  MOZ_ASSERT(slotCount >= ObjectElements::VALUES_PER_HEADER);
+  uint32_t arrayCapacity = slotCount - ObjectElements::VALUES_PER_HEADER;
+
+  AutoOutputRegister output(*this);
+  AutoScratchRegister result(allocator, masm);
+  AutoScratchRegister scratch(allocator, masm);
+  AutoScratchRegister site(allocator, masm);
+  AutoScratchRegisterMaybeOutput shape(allocator, masm, output);
+
+  Address shapeAddr(stubAddress(shapeOffset));
+  masm.loadPtr(shapeAddr, shape);
+
+  Address siteAddr(stubAddress(siteOffset));
+  masm.loadPtr(siteAddr, site);
+
+  allocator.discardStack(masm);
+
+  Label done;
+  Label fail;
+
+  masm.createArrayWithFixedElements(
+      result, shape, scratch, InvalidReg, arrayLength, arrayCapacity, 0, 0,
+      allocKind, gc::Heap::Default, &fail, AllocSiteInput(site));
+  masm.jump(&done);
+
+  {
+    masm.bind(&fail);
+
+    // We get here if the nursery is full (unlikely) but also for tenured
+    // allocations if the current arena is full and we need to allocate a new
+    // one (fairly common).
+
+    AutoStubFrame stubFrame(*this);
+    stubFrame.enter(masm, scratch);
+
+    masm.Push(site);
+    masm.Push(Imm32(int32_t(allocKind)));
+    masm.Push(Imm32(arrayLength));
+
+    using Fn =
+        ArrayObject* (*)(JSContext*, uint32_t, gc::AllocKind, gc::AllocSite*);
+    callVM<Fn, NewArrayObjectBaselineFallback>(masm);
+
+    stubFrame.leave(masm);
+    masm.storeCallPointerResult(result);
+  }
+
+  masm.bind(&done);
+  masm.tagValue(JSVAL_TYPE_OBJECT, result, output.valueReg());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitNewPlainObjectResult(uint32_t numFixedSlots,
+                                                       uint32_t numDynamicSlots,
+                                                       gc::AllocKind allocKind,
+                                                       uint32_t shapeOffset,
+                                                       uint32_t siteOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  AutoScratchRegister obj(allocator, masm);
+  AutoScratchRegister scratch(allocator, masm);
+  AutoScratchRegister site(allocator, masm);
+  AutoScratchRegisterMaybeOutput shape(allocator, masm, output);
+
+  Address shapeAddr(stubAddress(shapeOffset));
+  masm.loadPtr(shapeAddr, shape);
+
+  Address siteAddr(stubAddress(siteOffset));
+  masm.loadPtr(siteAddr, site);
+
+  allocator.discardStack(masm);
+
+  Label done;
+  Label fail;
+
+  masm.createPlainGCObject(obj, shape, scratch, shape, numFixedSlots,
+                           numDynamicSlots, allocKind, gc::Heap::Default, &fail,
+                           AllocSiteInput(site));
+  masm.jump(&done);
+
+  {
+    masm.bind(&fail);
+
+    // We get here if the nursery is full (unlikely) but also for tenured
+    // allocations if the current arena is full and we need to allocate a new
+    // one (fairly common).
+
+    AutoStubFrame stubFrame(*this);
+    stubFrame.enter(masm, scratch);
+
+    masm.Push(site);
+    masm.Push(Imm32(int32_t(allocKind)));
+    masm.loadPtr(shapeAddr, shape);  // This might have been overwritten.
+    masm.Push(shape);
+
+    using Fn = JSObject* (*)(JSContext*, Handle<SharedShape*>, gc::AllocKind,
+                             gc::AllocSite*);
+    callVM<Fn, NewPlainObjectBaselineFallback>(masm);
+
+    stubFrame.leave(masm);
+    masm.storeCallPointerResult(obj);
+  }
+
+  masm.bind(&done);
+  masm.tagValue(JSVAL_TYPE_OBJECT, obj, output.valueReg());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitBindFunctionResult(
+    ObjOperandId targetId, uint32_t argc, uint32_t templateObjectOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  AutoScratchRegister scratch(allocator, masm);
+
+  Register target = allocator.useRegister(masm, targetId);
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  // Push the arguments in reverse order.
+  for (uint32_t i = 0; i < argc; i++) {
+    Address argAddress(FramePointer,
+                       BaselineStubFrameLayout::Size() + i * sizeof(Value));
+    masm.pushValue(argAddress);
+  }
+  masm.moveStackPtrTo(scratch.get());
+
+  masm.Push(ImmWord(0));  // nullptr for maybeBound
+  masm.Push(Imm32(argc));
+  masm.Push(scratch);
+  masm.Push(target);
+
+  using Fn = BoundFunctionObject* (*)(JSContext*, Handle<JSObject*>, Value*,
+                                      uint32_t, Handle<BoundFunctionObject*>);
+  callVM<Fn, BoundFunctionObject::functionBindImpl>(masm);
+
+  stubFrame.leave(masm);
+  masm.storeCallPointerResult(scratch);
+
+  masm.tagValue(JSVAL_TYPE_OBJECT, scratch, output.valueReg());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitSpecializedBindFunctionResult(
+    ObjOperandId targetId, uint32_t argc, uint32_t templateObjectOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  AutoScratchRegisterMaybeOutput scratch1(allocator, masm);
+  AutoScratchRegister scratch2(allocator, masm);
+
+  Register target = allocator.useRegister(masm, targetId);
+
+  StubFieldOffset objectField(templateObjectOffset, StubField::Type::JSObject);
+  emitLoadStubField(objectField, scratch2);
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch1);
+
+  // Push the arguments in reverse order.
+  for (uint32_t i = 0; i < argc; i++) {
+    Address argAddress(FramePointer,
+                       BaselineStubFrameLayout::Size() + i * sizeof(Value));
+    masm.pushValue(argAddress);
+  }
+  masm.moveStackPtrTo(scratch1.get());
+
+  masm.Push(scratch2);
+  masm.Push(Imm32(argc));
+  masm.Push(scratch1);
+  masm.Push(target);
+
+  using Fn = BoundFunctionObject* (*)(JSContext*, Handle<JSObject*>, Value*,
+                                      uint32_t, Handle<BoundFunctionObject*>);
+  callVM<Fn, BoundFunctionObject::functionBindSpecializedBaseline>(masm);
+
+  stubFrame.leave(masm);
+  masm.storeCallPointerResult(scratch1);
+
+  masm.tagValue(JSVAL_TYPE_OBJECT, scratch1, output.valueReg());
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitCloseIterScriptedResult(
+    ObjOperandId iterId, ObjOperandId calleeId, CompletionKind kind,
+    uint32_t calleeNargs) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+  Register iter = allocator.useRegister(masm, iterId);
+  Register callee = allocator.useRegister(masm, calleeId);
+
+  AutoScratchRegister code(allocator, masm);
+  AutoScratchRegister scratch(allocator, masm);
+
+  masm.loadJitCodeRaw(callee, code);
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  // Call the return method.
+  masm.alignJitStackBasedOnNArgs(calleeNargs, /*countIncludesThis = */ false);
+  for (uint32_t i = 0; i < calleeNargs; i++) {
+    masm.pushValue(UndefinedValue());
+  }
+  masm.Push(TypedOrValueRegister(MIRType::Object, AnyRegister(iter)));
+  masm.Push(callee);
+  masm.PushFrameDescriptorForJitCall(FrameType::BaselineStub, /* argc = */ 0);
+
+  masm.callJit(code);
+
+  if (kind != CompletionKind::Throw) {
+    // Verify that the return value is an object.
+    Label success;
+    masm.branchTestObject(Assembler::Equal, JSReturnOperand, &success);
+
+    masm.Push(Imm32(int32_t(CheckIsObjectKind::IteratorReturn)));
+    using Fn = bool (*)(JSContext*, CheckIsObjectKind);
+    callVM<Fn, ThrowCheckIsObject>(masm);
+
+    masm.bind(&success);
+  }
+
+  stubFrame.leave(masm);
+  return true;
+}
+
+static void CallRegExpStub(MacroAssembler& masm, size_t jitZoneStubOffset,
+                           Register temp, Label* vmCall) {
+  // Call cx->zone()->jitZone()->regExpStub. We store a pointer to the RegExp
+  // stub in the IC stub to keep it alive, but we shouldn't use it if the stub
+  // has been discarded in the meantime (because we might have changed GC string
+  // pretenuring heuristics that affect behavior of the stub). This is uncommon
+  // but can happen if we discarded all JIT code but had some active (Baseline)
+  // scripts on the stack.
+  masm.loadJSContext(temp);
+  masm.loadPtr(Address(temp, JSContext::offsetOfZone()), temp);
+  masm.loadPtr(Address(temp, Zone::offsetOfJitZone()), temp);
+  masm.loadPtr(Address(temp, jitZoneStubOffset), temp);
+  masm.branchTestPtr(Assembler::Zero, temp, temp, vmCall);
+  masm.call(Address(temp, JitCode::offsetOfCode()));
+}
+
+// Used to move inputs to the registers expected by the RegExp stub.
+static void SetRegExpStubInputRegisters(MacroAssembler& masm,
+                                        Register* regexpSrc,
+                                        Register regexpDest, Register* inputSrc,
+                                        Register inputDest,
+                                        Register* lastIndexSrc,
+                                        Register lastIndexDest) {
+  MoveResolver& moves = masm.moveResolver();
+  if (*regexpSrc != regexpDest) {
+    masm.propagateOOM(moves.addMove(MoveOperand(*regexpSrc),
+                                    MoveOperand(regexpDest), MoveOp::GENERAL));
+    *regexpSrc = regexpDest;
+  }
+  if (*inputSrc != inputDest) {
+    masm.propagateOOM(moves.addMove(MoveOperand(*inputSrc),
+                                    MoveOperand(inputDest), MoveOp::GENERAL));
+    *inputSrc = inputDest;
+  }
+  if (lastIndexSrc && *lastIndexSrc != lastIndexDest) {
+    masm.propagateOOM(moves.addMove(MoveOperand(*lastIndexSrc),
+                                    MoveOperand(lastIndexDest), MoveOp::INT32));
+    *lastIndexSrc = lastIndexDest;
+  }
+
+  masm.propagateOOM(moves.resolve());
+
+  MoveEmitter emitter(masm);
+  emitter.emit(moves);
+  emitter.finish();
+}
+
+bool BaselineCacheIRCompiler::emitCallRegExpMatcherResult(
+    ObjOperandId regexpId, StringOperandId inputId, Int32OperandId lastIndexId,
+    uint32_t stubOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  Register regexp = allocator.useRegister(masm, regexpId);
+  Register input = allocator.useRegister(masm, inputId);
+  Register lastIndex = allocator.useRegister(masm, lastIndexId);
+  Register scratch = output.valueReg().scratchReg();
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  SetRegExpStubInputRegisters(masm, &regexp, RegExpMatcherRegExpReg, &input,
+                              RegExpMatcherStringReg, &lastIndex,
+                              RegExpMatcherLastIndexReg);
+
+  masm.reserveStack(RegExpReservedStack);
+
+  Label done, vmCall, vmCallNoMatches;
+  CallRegExpStub(masm, JitZone::offsetOfRegExpMatcherStub(), scratch,
+                 &vmCallNoMatches);
+  masm.branchTestUndefined(Assembler::Equal, JSReturnOperand, &vmCall);
+
+  masm.jump(&done);
+
+  {
+    Label pushedMatches;
+    masm.bind(&vmCallNoMatches);
+    masm.push(ImmWord(0));
+    masm.jump(&pushedMatches);
+
+    masm.bind(&vmCall);
+    masm.computeEffectiveAddress(
+        Address(masm.getStackPointer(), InputOutputDataSize), scratch);
+    masm.Push(scratch);
+
+    masm.bind(&pushedMatches);
+    masm.Push(lastIndex);
+    masm.Push(input);
+    masm.Push(regexp);
+
+    using Fn = bool (*)(JSContext*, HandleObject regexp, HandleString input,
+                        int32_t lastIndex, MatchPairs* pairs,
+                        MutableHandleValue output);
+    callVM<Fn, RegExpMatcherRaw>(masm);
+  }
+
+  masm.bind(&done);
+
+  static_assert(R0 == JSReturnOperand);
+
+  stubFrame.leave(masm);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitCallRegExpSearcherResult(
+    ObjOperandId regexpId, StringOperandId inputId, Int32OperandId lastIndexId,
+    uint32_t stubOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  Register regexp = allocator.useRegister(masm, regexpId);
+  Register input = allocator.useRegister(masm, inputId);
+  Register lastIndex = allocator.useRegister(masm, lastIndexId);
+  Register scratch = output.valueReg().scratchReg();
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  SetRegExpStubInputRegisters(masm, &regexp, RegExpSearcherRegExpReg, &input,
+                              RegExpSearcherStringReg, &lastIndex,
+                              RegExpSearcherLastIndexReg);
+  // Ensure `scratch` doesn't conflict with the stub's input registers.
+  scratch = ReturnReg;
+
+  masm.reserveStack(RegExpReservedStack);
+
+  Label done, vmCall, vmCallNoMatches;
+  CallRegExpStub(masm, JitZone::offsetOfRegExpSearcherStub(), scratch,
+                 &vmCallNoMatches);
+  masm.branch32(Assembler::Equal, scratch, Imm32(RegExpSearcherResultFailed),
+                &vmCall);
+
+  masm.jump(&done);
+
+  {
+    Label pushedMatches;
+    masm.bind(&vmCallNoMatches);
+    masm.push(ImmWord(0));
+    masm.jump(&pushedMatches);
+
+    masm.bind(&vmCall);
+    masm.computeEffectiveAddress(
+        Address(masm.getStackPointer(), InputOutputDataSize), scratch);
+    masm.Push(scratch);
+
+    masm.bind(&pushedMatches);
+    masm.Push(lastIndex);
+    masm.Push(input);
+    masm.Push(regexp);
+
+    using Fn = bool (*)(JSContext*, HandleObject regexp, HandleString input,
+                        int32_t lastIndex, MatchPairs* pairs, int32_t* result);
+    callVM<Fn, RegExpSearcherRaw>(masm);
+  }
+
+  masm.bind(&done);
+
+  masm.tagValue(JSVAL_TYPE_INT32, ReturnReg, output.valueReg());
+
+  stubFrame.leave(masm);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitRegExpBuiltinExecMatchResult(
+    ObjOperandId regexpId, StringOperandId inputId, uint32_t stubOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  Register regexp = allocator.useRegister(masm, regexpId);
+  Register input = allocator.useRegister(masm, inputId);
+  Register scratch = output.valueReg().scratchReg();
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  SetRegExpStubInputRegisters(masm, &regexp, RegExpMatcherRegExpReg, &input,
+                              RegExpMatcherStringReg, nullptr, InvalidReg);
+
+  masm.reserveStack(RegExpReservedStack);
+
+  Label done, vmCall, vmCallNoMatches;
+  CallRegExpStub(masm, JitZone::offsetOfRegExpExecMatchStub(), scratch,
+                 &vmCallNoMatches);
+  masm.branchTestUndefined(Assembler::Equal, JSReturnOperand, &vmCall);
+
+  masm.jump(&done);
+
+  {
+    Label pushedMatches;
+    masm.bind(&vmCallNoMatches);
+    masm.push(ImmWord(0));
+    masm.jump(&pushedMatches);
+
+    masm.bind(&vmCall);
+    masm.computeEffectiveAddress(
+        Address(masm.getStackPointer(), InputOutputDataSize), scratch);
+    masm.Push(scratch);
+
+    masm.bind(&pushedMatches);
+    masm.Push(input);
+    masm.Push(regexp);
+
+    using Fn =
+        bool (*)(JSContext*, Handle<RegExpObject*> regexp, HandleString input,
+                 MatchPairs* pairs, MutableHandleValue output);
+    callVM<Fn, RegExpBuiltinExecMatchFromJit>(masm);
+  }
+
+  masm.bind(&done);
+
+  static_assert(R0 == JSReturnOperand);
+
+  stubFrame.leave(masm);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitRegExpBuiltinExecTestResult(
+    ObjOperandId regexpId, StringOperandId inputId, uint32_t stubOffset) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  Register regexp = allocator.useRegister(masm, regexpId);
+  Register input = allocator.useRegister(masm, inputId);
+  Register scratch = output.valueReg().scratchReg();
+
+  allocator.discardStack(masm);
+
+  AutoStubFrame stubFrame(*this);
+  stubFrame.enter(masm, scratch);
+
+  SetRegExpStubInputRegisters(masm, &regexp, RegExpExecTestRegExpReg, &input,
+                              RegExpExecTestStringReg, nullptr, InvalidReg);
+  // Ensure `scratch` doesn't conflict with the stub's input registers.
+  scratch = ReturnReg;
+
+  Label done, vmCall;
+  CallRegExpStub(masm, JitZone::offsetOfRegExpExecTestStub(), scratch, &vmCall);
+  masm.branch32(Assembler::Equal, scratch, Imm32(RegExpExecTestResultFailed),
+                &vmCall);
+
+  masm.jump(&done);
+
+  {
+    masm.bind(&vmCall);
+
+    masm.Push(input);
+    masm.Push(regexp);
+
+    using Fn = bool (*)(JSContext*, Handle<RegExpObject*> regexp,
+                        HandleString input, bool* result);
+    callVM<Fn, RegExpBuiltinExecTestFromJit>(masm);
+  }
+
+  masm.bind(&done);
+
+  masm.tagValue(JSVAL_TYPE_BOOLEAN, ReturnReg, output.valueReg());
+
+  stubFrame.leave(masm);
+  return true;
+}
+
+bool BaselineCacheIRCompiler::emitRegExpHasCaptureGroupsResult(
+    ObjOperandId regexpId, StringOperandId inputId) {
+  JitSpew(JitSpew_Codegen, "%s", __FUNCTION__);
+
+  AutoOutputRegister output(*this);
+  Register regexp = allocator.useRegister(masm, regexpId);
+  Register input = allocator.useRegister(masm, inputId);
+  AutoScratchRegisterMaybeOutput scratch(allocator, masm, output);
+
+  allocator.discardStack(masm);
+
+  // Load RegExpShared in |scratch|.
+  Label vmCall;
+  masm.loadParsedRegExpShared(regexp, scratch, &vmCall);
+
+  // Return true iff pairCount > 1.
+  Label returnTrue, done;
+  masm.branch32(Assembler::Above,
+                Address(scratch, RegExpShared::offsetOfPairCount()), Imm32(1),
+                &returnTrue);
+  masm.moveValue(BooleanValue(false), output.valueReg());
+  masm.jump(&done);
+
+  masm.bind(&returnTrue);
+  masm.moveValue(BooleanValue(true), output.valueReg());
+  masm.jump(&done);
+
+  {
+    masm.bind(&vmCall);
+
+    AutoStubFrame stubFrame(*this);
+    stubFrame.enter(masm, scratch);
+
+    masm.Push(input);
+    masm.Push(regexp);
+
+    using Fn =
+        bool (*)(JSContext*, Handle<RegExpObject*>, Handle<JSString*>, bool*);
+    callVM<Fn, RegExpHasCaptureGroups>(masm);
+
+    stubFrame.leave(masm);
+    masm.storeCallBoolResult(scratch);
+    masm.tagValue(JSVAL_TYPE_BOOLEAN, scratch, output.valueReg());
+  }
+
+  masm.bind(&done);
+  return true;
+}