Adding upstream version 86.0.1.upstream/86.0.1upstream

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

1 files changed, 1345 insertions, 0 deletions

diff --git a/js/src/jit/mips32/Trampoline-mips32.cpp b/js/src/jit/mips32/Trampoline-mips32.cpp
new file mode 100644
index 0000000000..7506953cd6
--- /dev/null
+++ b/js/src/jit/mips32/Trampoline-mips32.cpp
@@ -0,0 +1,1345 @@
+/* -*- 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 "mozilla/DebugOnly.h"
+
+#include "jit/Bailouts.h"
+#include "jit/BaselineFrame.h"
+#include "jit/CalleeToken.h"
+#include "jit/JitFrames.h"
+#include "jit/JitRuntime.h"
+#include "jit/JitSpewer.h"
+#include "jit/mips-shared/SharedICHelpers-mips-shared.h"
+#include "jit/mips32/Bailouts-mips32.h"
+#ifdef JS_ION_PERF
+#  include "jit/PerfSpewer.h"
+#endif
+#include "jit/VMFunctions.h"
+#include "vm/JitActivation.h"  // js::jit::JitActivation
+#include "vm/JSContext.h"
+#include "vm/Realm.h"
+
+#include "jit/MacroAssembler-inl.h"
+
+using namespace js;
+using namespace js::jit;
+
+static_assert(sizeof(uintptr_t) == sizeof(uint32_t), "Not 64-bit clean.");
+
+struct EnterJITRegs {
+  double f30;
+  double f28;
+  double f26;
+  double f24;
+  double f22;
+  double f20;
+
+  // non-volatile registers.
+  uintptr_t ra;
+  uintptr_t fp;
+  uintptr_t s7;
+  uintptr_t s6;
+  uintptr_t s5;
+  uintptr_t s4;
+  uintptr_t s3;
+  uintptr_t s2;
+  uintptr_t s1;
+  uintptr_t s0;
+};
+
+struct EnterJITArgs {
+  // First 4 argumet placeholders
+  void* jitcode;  // <- sp points here when function is entered.
+  int maxArgc;
+  Value* maxArgv;
+  InterpreterFrame* fp;
+
+  // Arguments on stack
+  CalleeToken calleeToken;
+  JSObject* scopeChain;
+  size_t numStackValues;
+  Value* vp;
+};
+
+static void GenerateReturn(MacroAssembler& masm, int returnCode) {
+  MOZ_ASSERT(masm.framePushed() == sizeof(EnterJITRegs));
+
+  // Restore non-volatile registers
+  masm.as_lw(s0, StackPointer, offsetof(EnterJITRegs, s0));
+  masm.as_lw(s1, StackPointer, offsetof(EnterJITRegs, s1));
+  masm.as_lw(s2, StackPointer, offsetof(EnterJITRegs, s2));
+  masm.as_lw(s3, StackPointer, offsetof(EnterJITRegs, s3));
+  masm.as_lw(s4, StackPointer, offsetof(EnterJITRegs, s4));
+  masm.as_lw(s5, StackPointer, offsetof(EnterJITRegs, s5));
+  masm.as_lw(s6, StackPointer, offsetof(EnterJITRegs, s6));
+  masm.as_lw(s7, StackPointer, offsetof(EnterJITRegs, s7));
+  masm.as_lw(fp, StackPointer, offsetof(EnterJITRegs, fp));
+  masm.as_lw(ra, StackPointer, offsetof(EnterJITRegs, ra));
+
+  // Restore non-volatile floating point registers
+  masm.as_ldc1(f20, StackPointer, offsetof(EnterJITRegs, f20));
+  masm.as_ldc1(f22, StackPointer, offsetof(EnterJITRegs, f22));
+  masm.as_ldc1(f24, StackPointer, offsetof(EnterJITRegs, f24));
+  masm.as_ldc1(f26, StackPointer, offsetof(EnterJITRegs, f26));
+  masm.as_ldc1(f28, StackPointer, offsetof(EnterJITRegs, f28));
+  masm.as_ldc1(f30, StackPointer, offsetof(EnterJITRegs, f30));
+
+  masm.freeStack(sizeof(EnterJITRegs));
+
+  masm.branch(ra);
+}
+
+static void GeneratePrologue(MacroAssembler& masm) {
+  // Save non-volatile registers. These must be saved by the trampoline,
+  // rather than the JIT'd code, because they are scanned by the conservative
+  // scanner.
+  masm.reserveStack(sizeof(EnterJITRegs));
+  masm.as_sw(s0, StackPointer, offsetof(EnterJITRegs, s0));
+  masm.as_sw(s1, StackPointer, offsetof(EnterJITRegs, s1));
+  masm.as_sw(s2, StackPointer, offsetof(EnterJITRegs, s2));
+  masm.as_sw(s3, StackPointer, offsetof(EnterJITRegs, s3));
+  masm.as_sw(s4, StackPointer, offsetof(EnterJITRegs, s4));
+  masm.as_sw(s5, StackPointer, offsetof(EnterJITRegs, s5));
+  masm.as_sw(s6, StackPointer, offsetof(EnterJITRegs, s6));
+  masm.as_sw(s7, StackPointer, offsetof(EnterJITRegs, s7));
+  masm.as_sw(fp, StackPointer, offsetof(EnterJITRegs, fp));
+  masm.as_sw(ra, StackPointer, offsetof(EnterJITRegs, ra));
+
+  masm.as_sdc1(f20, StackPointer, offsetof(EnterJITRegs, f20));
+  masm.as_sdc1(f22, StackPointer, offsetof(EnterJITRegs, f22));
+  masm.as_sdc1(f24, StackPointer, offsetof(EnterJITRegs, f24));
+  masm.as_sdc1(f26, StackPointer, offsetof(EnterJITRegs, f26));
+  masm.as_sdc1(f28, StackPointer, offsetof(EnterJITRegs, f28));
+  masm.as_sdc1(f30, StackPointer, offsetof(EnterJITRegs, f30));
+}
+
+/*
+ * This method generates a trampoline for a c++ function with the following
+ * signature:
+ *   void enter(void* code, int argc, Value* argv, InterpreterFrame* fp,
+ *              CalleeToken calleeToken, JSObject* scopeChain, Value* vp)
+ *   ...using standard EABI calling convention
+ */
+void JitRuntime::generateEnterJIT(JSContext* cx, MacroAssembler& masm) {
+  enterJITOffset_ = startTrampolineCode(masm);
+
+  const Register reg_code = a0;
+  const Register reg_argc = a1;
+  const Register reg_argv = a2;
+  const mozilla::DebugOnly<Register> reg_frame = a3;
+
+  MOZ_ASSERT(OsrFrameReg == reg_frame);
+
+  GeneratePrologue(masm);
+
+  const Address slotToken(
+      sp, sizeof(EnterJITRegs) + offsetof(EnterJITArgs, calleeToken));
+  const Address slotVp(sp, sizeof(EnterJITRegs) + offsetof(EnterJITArgs, vp));
+
+  // Save stack pointer into s4
+  masm.movePtr(StackPointer, s4);
+
+  // Load calleeToken into s2.
+  masm.loadPtr(slotToken, s2);
+
+  // Save stack pointer as baseline frame.
+  masm.movePtr(StackPointer, BaselineFrameReg);
+
+  // Load the number of actual arguments into s3.
+  masm.loadPtr(slotVp, s3);
+  masm.unboxInt32(Address(s3, 0), s3);
+
+  /***************************************************************
+  Loop over argv vector, push arguments onto stack in reverse order
+  ***************************************************************/
+
+  // if we are constructing, that also needs to include newTarget
+  {
+    Label noNewTarget;
+    masm.branchTest32(Assembler::Zero, s2,
+                      Imm32(CalleeToken_FunctionConstructing), &noNewTarget);
+
+    masm.add32(Imm32(1), reg_argc);
+
+    masm.bind(&noNewTarget);
+  }
+
+  masm.as_sll(s0, reg_argc, 3);  // s0 = argc * 8
+  masm.addPtr(reg_argv, s0);     // s0 = argv + argc * 8
+
+  // Loop over arguments, copying them from an unknown buffer onto the Ion
+  // stack so they can be accessed from JIT'ed code.
+  Label header, footer;
+  // If there aren't any arguments, don't do anything
+  masm.ma_b(s0, reg_argv, &footer, Assembler::BelowOrEqual, ShortJump);
+  {
+    masm.bind(&header);
+
+    masm.subPtr(Imm32(2 * sizeof(uintptr_t)), s0);
+    masm.subPtr(Imm32(2 * sizeof(uintptr_t)), StackPointer);
+
+    ValueOperand value = ValueOperand(s6, s7);
+    masm.loadValue(Address(s0, 0), value);
+    masm.storeValue(value, Address(StackPointer, 0));
+
+    masm.ma_b(s0, reg_argv, &header, Assembler::Above, ShortJump);
+  }
+  masm.bind(&footer);
+
+  masm.subPtr(Imm32(2 * sizeof(uintptr_t)), StackPointer);
+  masm.storePtr(s3,
+                Address(StackPointer, sizeof(uintptr_t)));  // actual arguments
+  masm.storePtr(s2, Address(StackPointer, 0));              // callee token
+
+  masm.subPtr(StackPointer, s4);
+  masm.makeFrameDescriptor(s4, FrameType::CppToJSJit, JitFrameLayout::Size());
+  masm.push(s4);  // descriptor
+
+  CodeLabel returnLabel;
+  CodeLabel oomReturnLabel;
+  {
+    // Handle Interpreter -> Baseline OSR.
+    AllocatableGeneralRegisterSet regs(GeneralRegisterSet::All());
+    regs.take(OsrFrameReg);
+    regs.take(BaselineFrameReg);
+    regs.take(reg_code);
+    regs.take(ReturnReg);
+
+    const Address slotNumStackValues(
+        BaselineFrameReg,
+        sizeof(EnterJITRegs) + offsetof(EnterJITArgs, numStackValues));
+    const Address slotScopeChain(
+        BaselineFrameReg,
+        sizeof(EnterJITRegs) + offsetof(EnterJITArgs, scopeChain));
+
+    Label notOsr;
+    masm.ma_b(OsrFrameReg, OsrFrameReg, &notOsr, Assembler::Zero, ShortJump);
+
+    Register scratch = regs.takeAny();
+
+    Register numStackValues = regs.takeAny();
+    masm.load32(slotNumStackValues, numStackValues);
+
+    // Push return address.
+    masm.subPtr(Imm32(sizeof(uintptr_t)), StackPointer);
+    masm.ma_li(scratch, &returnLabel);
+    masm.storePtr(scratch, Address(StackPointer, 0));
+
+    // Push previous frame pointer.
+    masm.subPtr(Imm32(sizeof(uintptr_t)), StackPointer);
+    masm.storePtr(BaselineFrameReg, Address(StackPointer, 0));
+
+    // Reserve frame.
+    Register framePtr = BaselineFrameReg;
+    masm.subPtr(Imm32(BaselineFrame::Size()), StackPointer);
+    masm.movePtr(StackPointer, framePtr);
+
+    // Reserve space for locals and stack values.
+    masm.ma_sll(scratch, numStackValues, Imm32(3));
+    masm.subPtr(scratch, StackPointer);
+
+    // Enter exit frame.
+    masm.addPtr(
+        Imm32(BaselineFrame::Size() + BaselineFrame::FramePointerOffset),
+        scratch);
+    masm.makeFrameDescriptor(scratch, FrameType::BaselineJS,
+                             ExitFrameLayout::Size());
+
+    // Push frame descriptor and fake return address.
+    masm.reserveStack(2 * sizeof(uintptr_t));
+    masm.storePtr(
+        scratch, Address(StackPointer, sizeof(uintptr_t)));  // Frame descriptor
+    masm.storePtr(zero, Address(StackPointer, 0));  // fake return address
+
+    // No GC things to mark, push a bare token.
+    masm.loadJSContext(scratch);
+    masm.enterFakeExitFrame(scratch, scratch, ExitFrameType::Bare);
+
+    masm.reserveStack(2 * sizeof(uintptr_t));
+    masm.storePtr(framePtr,
+                  Address(StackPointer, sizeof(uintptr_t)));  // BaselineFrame
+    masm.storePtr(reg_code, Address(StackPointer, 0));        // jitcode
+
+    using Fn = bool (*)(BaselineFrame * frame, InterpreterFrame * interpFrame,
+                        uint32_t numStackValues);
+    masm.setupUnalignedABICall(scratch);
+    masm.passABIArg(BaselineFrameReg);  // BaselineFrame
+    masm.passABIArg(OsrFrameReg);       // InterpreterFrame
+    masm.passABIArg(numStackValues);
+    masm.callWithABI<Fn, jit::InitBaselineFrameForOsr>(
+        MoveOp::GENERAL, CheckUnsafeCallWithABI::DontCheckHasExitFrame);
+
+    regs.add(OsrFrameReg);
+    regs.take(JSReturnOperand);
+    Register jitcode = regs.takeAny();
+    masm.loadPtr(Address(StackPointer, 0), jitcode);
+    masm.loadPtr(Address(StackPointer, sizeof(uintptr_t)), framePtr);
+    masm.freeStack(2 * sizeof(uintptr_t));
+
+    Label error;
+    masm.freeStack(ExitFrameLayout::SizeWithFooter());
+    masm.addPtr(Imm32(BaselineFrame::Size()), framePtr);
+    masm.branchIfFalseBool(ReturnReg, &error);
+
+    // If OSR-ing, then emit instrumentation for setting lastProfilerFrame
+    // if profiler instrumentation is enabled.
+    {
+      Label skipProfilingInstrumentation;
+      Register realFramePtr = numStackValues;
+      AbsoluteAddress addressOfEnabled(
+          cx->runtime()->geckoProfiler().addressOfEnabled());
+      masm.branch32(Assembler::Equal, addressOfEnabled, Imm32(0),
+                    &skipProfilingInstrumentation);
+      masm.ma_addu(realFramePtr, framePtr, Imm32(sizeof(void*)));
+      masm.profilerEnterFrame(realFramePtr, scratch);
+      masm.bind(&skipProfilingInstrumentation);
+    }
+
+    masm.jump(jitcode);
+
+    // OOM: load error value, discard return address and previous frame
+    // pointer and return.
+    masm.bind(&error);
+    masm.movePtr(framePtr, StackPointer);
+    masm.addPtr(Imm32(2 * sizeof(uintptr_t)), StackPointer);
+    masm.moveValue(MagicValue(JS_ION_ERROR), JSReturnOperand);
+    masm.ma_li(scratch, &oomReturnLabel);
+    masm.jump(scratch);
+
+    masm.bind(&notOsr);
+    // Load the scope chain in R1.
+    MOZ_ASSERT(R1.scratchReg() != reg_code);
+    masm.loadPtr(slotScopeChain, R1.scratchReg());
+  }
+
+  // The call will push the return address on the stack, thus we check that
+  // the stack would be aligned once the call is complete.
+  masm.assertStackAlignment(JitStackAlignment, sizeof(uintptr_t));
+
+  // Call the function with pushing return address to stack.
+  masm.callJitNoProfiler(reg_code);
+
+  {
+    // Interpreter -> Baseline OSR will return here.
+    masm.bind(&returnLabel);
+    masm.addCodeLabel(returnLabel);
+    masm.bind(&oomReturnLabel);
+    masm.addCodeLabel(oomReturnLabel);
+  }
+
+  // Pop arguments off the stack.
+  // s0 <- 8*argc (size of all arguments we pushed on the stack)
+  masm.pop(s0);
+  masm.rshiftPtr(Imm32(FRAMESIZE_SHIFT), s0);
+  masm.addPtr(s0, StackPointer);
+
+  // Store the returned value into the slotVp
+  masm.loadPtr(slotVp, s1);
+  masm.storeValue(JSReturnOperand, Address(s1, 0));
+
+  // Restore non-volatile registers and return.
+  GenerateReturn(masm, ShortJump);
+}
+
+void JitRuntime::generateInvalidator(MacroAssembler& masm, Label* bailoutTail) {
+  invalidatorOffset_ = startTrampolineCode(masm);
+
+  // NOTE: Members ionScript_ and osiPointReturnAddress_ of
+  // InvalidationBailoutStack are already on the stack.
+  static const uint32_t STACK_DATA_SIZE =
+      sizeof(InvalidationBailoutStack) - 2 * sizeof(uintptr_t);
+
+  // Stack has to be alligned here. If not, we will have to fix it.
+  masm.checkStackAlignment();
+
+  // Make room for data on stack.
+  masm.subPtr(Imm32(STACK_DATA_SIZE), StackPointer);
+
+  // Save general purpose registers
+  for (uint32_t i = 0; i < Registers::Total; i++) {
+    Address address =
+        Address(StackPointer, InvalidationBailoutStack::offsetOfRegs() +
+                                  i * sizeof(uintptr_t));
+    masm.storePtr(Register::FromCode(i), address);
+  }
+
+  // Save floating point registers
+  // We can use as_sd because stack is alligned.
+  for (uint32_t i = 0; i < FloatRegisters::TotalDouble; i++) {
+    masm.as_sdc1(
+        FloatRegister::FromIndex(i, FloatRegister::Double), StackPointer,
+        InvalidationBailoutStack::offsetOfFpRegs() + i * sizeof(double));
+  }
+
+  // Pass pointer to InvalidationBailoutStack structure.
+  masm.movePtr(StackPointer, a0);
+
+  // Reserve place for return value and BailoutInfo pointer
+  masm.subPtr(Imm32(2 * sizeof(uintptr_t)), StackPointer);
+  // Pass pointer to return value.
+  masm.ma_addu(a1, StackPointer, Imm32(sizeof(uintptr_t)));
+  // Pass pointer to BailoutInfo
+  masm.movePtr(StackPointer, a2);
+
+  using Fn = bool (*)(InvalidationBailoutStack * sp, size_t * frameSizeOut,
+                      BaselineBailoutInfo * *info);
+  masm.setupAlignedABICall();
+  masm.passABIArg(a0);
+  masm.passABIArg(a1);
+  masm.passABIArg(a2);
+  masm.callWithABI<Fn, InvalidationBailout>(
+      MoveOp::GENERAL, CheckUnsafeCallWithABI::DontCheckOther);
+
+  masm.loadPtr(Address(StackPointer, 0), a2);
+  masm.loadPtr(Address(StackPointer, sizeof(uintptr_t)), a1);
+  // Remove the return address, the IonScript, the register state
+  // (InvaliationBailoutStack) and the space that was allocated for the
+  // return value.
+  masm.addPtr(Imm32(sizeof(InvalidationBailoutStack) + 2 * sizeof(uintptr_t)),
+              StackPointer);
+  // remove the space that this frame was using before the bailout
+  // (computed by InvalidationBailout)
+  masm.addPtr(a1, StackPointer);
+
+  // Jump to shared bailout tail. The BailoutInfo pointer has to be in r2.
+  masm.jump(bailoutTail);
+}
+
+void JitRuntime::generateArgumentsRectifier(MacroAssembler& masm,
+                                            ArgumentsRectifierKind kind) {
+  switch (kind) {
+    case ArgumentsRectifierKind::Normal:
+      argumentsRectifierOffset_ = startTrampolineCode(masm);
+      break;
+    case ArgumentsRectifierKind::TrialInlining:
+      trialInliningArgumentsRectifierOffset_ = startTrampolineCode(masm);
+      break;
+  }
+  masm.pushReturnAddress();
+
+  Register numActArgsReg = t6;
+  Register calleeTokenReg = t7;
+  Register numArgsReg = t5;
+
+  // Load the number of actual arguments into numActArgsReg
+  masm.loadPtr(
+      Address(StackPointer, RectifierFrameLayout::offsetOfNumActualArgs()),
+      numActArgsReg);
+
+  // Load the number of |undefined|s to push into t1.
+  masm.loadPtr(
+      Address(StackPointer, RectifierFrameLayout::offsetOfCalleeToken()),
+      calleeTokenReg);
+
+  // Copy the number of actual arguments into s3.
+  masm.mov(numActArgsReg, s3);
+
+  masm.mov(calleeTokenReg, numArgsReg);
+  masm.andPtr(Imm32(CalleeTokenMask), numArgsReg);
+  masm.load16ZeroExtend(Address(numArgsReg, JSFunction::offsetOfNargs()),
+                        numArgsReg);
+
+  masm.as_subu(t1, numArgsReg, s3);
+
+  // Get the topmost argument.
+  masm.ma_sll(t0, s3, Imm32(3));  // t0 <- nargs * 8
+  masm.as_addu(t2, sp, t0);       // t2 <- sp + nargs * 8
+  masm.addPtr(Imm32(sizeof(RectifierFrameLayout)), t2);
+
+  {
+    Label notConstructing;
+
+    masm.branchTest32(Assembler::Zero, calleeTokenReg,
+                      Imm32(CalleeToken_FunctionConstructing),
+                      &notConstructing);
+
+    // Add sizeof(Value) to overcome |this|
+    masm.subPtr(Imm32(sizeof(Value)), StackPointer);
+    masm.load32(Address(t2, NUNBOX32_TYPE_OFFSET + sizeof(Value)), t0);
+    masm.store32(t0, Address(StackPointer, NUNBOX32_TYPE_OFFSET));
+    masm.load32(Address(t2, NUNBOX32_PAYLOAD_OFFSET + sizeof(Value)), t0);
+    masm.store32(t0, Address(StackPointer, NUNBOX32_PAYLOAD_OFFSET));
+
+    // Include the newly pushed newTarget value in the frame size
+    // calculated below.
+    masm.add32(Imm32(1), numArgsReg);
+
+    masm.bind(&notConstructing);
+  }
+
+  // Push undefined.
+  masm.moveValue(UndefinedValue(), ValueOperand(t3, t4));
+  {
+    Label undefLoopTop;
+    masm.bind(&undefLoopTop);
+
+    masm.subPtr(Imm32(sizeof(Value)), StackPointer);
+    masm.storeValue(ValueOperand(t3, t4), Address(StackPointer, 0));
+    masm.sub32(Imm32(1), t1);
+
+    masm.ma_b(t1, t1, &undefLoopTop, Assembler::NonZero, ShortJump);
+  }
+
+  // Push arguments, |nargs| + 1 times (to include |this|).
+  {
+    Label copyLoopTop, initialSkip;
+
+    masm.ma_b(&initialSkip, ShortJump);
+
+    masm.bind(&copyLoopTop);
+    masm.subPtr(Imm32(sizeof(Value)), t2);
+    masm.sub32(Imm32(1), s3);
+
+    masm.bind(&initialSkip);
+
+    MOZ_ASSERT(sizeof(Value) == 2 * sizeof(uint32_t));
+    // Read argument and push to stack.
+    masm.subPtr(Imm32(sizeof(Value)), StackPointer);
+    masm.load32(Address(t2, NUNBOX32_TYPE_OFFSET), t0);
+    masm.store32(t0, Address(StackPointer, NUNBOX32_TYPE_OFFSET));
+    masm.load32(Address(t2, NUNBOX32_PAYLOAD_OFFSET), t0);
+    masm.store32(t0, Address(StackPointer, NUNBOX32_PAYLOAD_OFFSET));
+
+    masm.ma_b(s3, s3, &copyLoopTop, Assembler::NonZero, ShortJump);
+  }
+
+  // translate the framesize from values into bytes
+  masm.ma_addu(t0, numArgsReg, Imm32(1));
+  masm.lshiftPtr(Imm32(3), t0);
+
+  // Construct sizeDescriptor.
+  masm.makeFrameDescriptor(t0, FrameType::Rectifier, JitFrameLayout::Size());
+
+  // Construct JitFrameLayout.
+  masm.subPtr(Imm32(3 * sizeof(uintptr_t)), StackPointer);
+  // Push actual arguments.
+  masm.storePtr(numActArgsReg, Address(StackPointer, 2 * sizeof(uintptr_t)));
+  // Push callee token.
+  masm.storePtr(calleeTokenReg, Address(StackPointer, sizeof(uintptr_t)));
+  // Push frame descriptor.
+  masm.storePtr(t0, Address(StackPointer, 0));
+
+  // Call the target function.
+  masm.andPtr(Imm32(CalleeTokenMask), calleeTokenReg);
+  switch (kind) {
+    case ArgumentsRectifierKind::Normal:
+      masm.loadJitCodeRaw(calleeTokenReg, t1);
+      argumentsRectifierReturnOffset_ = masm.callJitNoProfiler(t1);
+      break;
+    case ArgumentsRectifierKind::TrialInlining:
+      Label noBaselineScript, done;
+      masm.loadBaselineJitCodeRaw(calleeTokenReg, t1, &noBaselineScript);
+      masm.callJitNoProfiler(t1);
+      masm.jump(&done);
+
+      // See BaselineCacheIRCompiler::emitCallInlinedFunction.
+      masm.bind(&noBaselineScript);
+      masm.loadJitCodeRaw(calleeTokenReg, t1);
+      masm.callJitNoProfiler(t1);
+      masm.bind(&done);
+      break;
+  }
+
+  // arg1
+  //  ...
+  // argN
+  // num actual args
+  // callee token
+  // sizeDescriptor     <- sp now
+  // return address
+
+  // Remove the rectifier frame.
+  // t0 <- descriptor with FrameType.
+  masm.loadPtr(Address(StackPointer, 0), t0);
+  masm.rshiftPtr(Imm32(FRAMESIZE_SHIFT), t0);  // t0 <- descriptor.
+
+  // Discard descriptor, calleeToken and number of actual arguments.
+  masm.addPtr(Imm32(3 * sizeof(uintptr_t)), StackPointer);
+
+  // arg1
+  //  ...
+  // argN               <- sp now; t0 <- frame descriptor
+  // num actual args
+  // callee token
+  // sizeDescriptor
+  // return address
+
+  // Discard pushed arguments.
+  masm.addPtr(t0, StackPointer);
+
+  masm.ret();
+}
+
+// NOTE: Members snapshotOffset_ and padding_ of BailoutStack
+// are not stored in PushBailoutFrame().
+static const uint32_t bailoutDataSize =
+    sizeof(BailoutStack) - 2 * sizeof(uintptr_t);
+static const uint32_t bailoutInfoOutParamSize = 2 * sizeof(uintptr_t);
+
+/* There are two different stack layouts when doing bailout. They are
+ * represented via class BailoutStack.
+ *
+ * - First case is when bailout is done trough bailout table. In this case
+ * table offset is stored in $ra (look at JitRuntime::generateBailoutTable())
+ * and thunk code should save it on stack. In this case frameClassId_ cannot
+ * be NO_FRAME_SIZE_CLASS_ID. Members snapshotOffset_ and padding_ are not on
+ * the stack.
+ *
+ * - Other case is when bailout is done via out of line code (lazy bailout).
+ * In this case frame size is stored in $ra (look at
+ * CodeGeneratorMIPS::generateOutOfLineCode()) and thunk code should save it
+ * on stack. Other difference is that members snapshotOffset_ and padding_ are
+ * pushed to the stack by CodeGeneratorMIPS::visitOutOfLineBailout(). Field
+ * frameClassId_ is forced to be NO_FRAME_SIZE_CLASS_ID
+ * (See: JitRuntime::generateBailoutHandler).
+ */
+static void PushBailoutFrame(MacroAssembler& masm, uint32_t frameClass,
+                             Register spArg) {
+  // Make sure that alignment is proper.
+  masm.checkStackAlignment();
+
+  // Make room for data.
+  masm.subPtr(Imm32(bailoutDataSize), StackPointer);
+
+  // Save general purpose registers.
+  for (uint32_t i = 0; i < Registers::Total; i++) {
+    uint32_t off = BailoutStack::offsetOfRegs() + i * sizeof(uintptr_t);
+    masm.storePtr(Register::FromCode(i), Address(StackPointer, off));
+  }
+
+#ifdef ENABLE_WASM_SIMD
+  // What to do for SIMD?
+#  error "Needs more careful logic if SIMD is enabled"
+#endif
+
+  // Save floating point registers
+  // We can use as_sdc1 because stack is alligned.
+  for (uint32_t i = 0; i < FloatRegisters::TotalDouble; i++) {
+    masm.as_sdc1(FloatRegister::FromIndex(i, FloatRegister::Double),
+                 StackPointer,
+                 BailoutStack::offsetOfFpRegs() + i * sizeof(double));
+  }
+
+  // Store the frameSize_ or tableOffset_ stored in ra
+  // See: JitRuntime::generateBailoutTable()
+  // See: CodeGeneratorMIPS::generateOutOfLineCode()
+  masm.storePtr(ra, Address(StackPointer, BailoutStack::offsetOfFrameSize()));
+
+  // Put frame class to stack
+  masm.storePtr(ImmWord(frameClass),
+                Address(StackPointer, BailoutStack::offsetOfFrameClass()));
+
+  // Put pointer to BailoutStack as first argument to the Bailout()
+  masm.movePtr(StackPointer, spArg);
+}
+
+static void GenerateBailoutThunk(MacroAssembler& masm, uint32_t frameClass,
+                                 Label* bailoutTail) {
+  PushBailoutFrame(masm, frameClass, a0);
+
+  // Put pointer to BailoutInfo
+  masm.subPtr(Imm32(bailoutInfoOutParamSize), StackPointer);
+  masm.storePtr(ImmPtr(nullptr), Address(StackPointer, 0));
+  masm.movePtr(StackPointer, a1);
+
+  using Fn = bool (*)(BailoutStack * sp, BaselineBailoutInfo * *info);
+  masm.setupAlignedABICall();
+  masm.passABIArg(a0);
+  masm.passABIArg(a1);
+  masm.callWithABI<Fn, Bailout>(MoveOp::GENERAL,
+                                CheckUnsafeCallWithABI::DontCheckOther);
+
+  // Get BailoutInfo pointer
+  masm.loadPtr(Address(StackPointer, 0), a2);
+
+  // Remove both the bailout frame and the topmost Ion frame's stack.
+  if (frameClass == NO_FRAME_SIZE_CLASS_ID) {
+    // Load frameSize from stack
+    masm.loadPtr(Address(StackPointer, bailoutInfoOutParamSize +
+                                           BailoutStack::offsetOfFrameSize()),
+                 a1);
+
+    // Remove complete BailoutStack class and data after it
+    masm.addPtr(Imm32(sizeof(BailoutStack) + bailoutInfoOutParamSize),
+                StackPointer);
+    // Remove frame size srom stack
+    masm.addPtr(a1, StackPointer);
+  } else {
+    uint32_t frameSize = FrameSizeClass::FromClass(frameClass).frameSize();
+    // Remove the data this fuction added and frame size.
+    masm.addPtr(Imm32(bailoutDataSize + bailoutInfoOutParamSize + frameSize),
+                StackPointer);
+  }
+
+  // Jump to shared bailout tail. The BailoutInfo pointer has to be in a2.
+  masm.jump(bailoutTail);
+}
+
+JitRuntime::BailoutTable JitRuntime::generateBailoutTable(MacroAssembler& masm,
+                                                          Label* bailoutTail,
+                                                          uint32_t frameClass) {
+  uint32_t offset = startTrampolineCode(masm);
+
+  Label bailout;
+  for (size_t i = 0; i < BAILOUT_TABLE_SIZE; i++) {
+    // Calculate offset to the end of table
+    int32_t offset = (BAILOUT_TABLE_SIZE - i) * BAILOUT_TABLE_ENTRY_SIZE;
+
+    // We use the 'ra' as table offset later in GenerateBailoutThunk
+    masm.as_bal(BOffImm16(offset));
+    masm.nop();
+  }
+  masm.bind(&bailout);
+
+  GenerateBailoutThunk(masm, frameClass, bailoutTail);
+
+  return BailoutTable(offset, masm.currentOffset() - offset);
+}
+
+void JitRuntime::generateBailoutHandler(MacroAssembler& masm,
+                                        Label* bailoutTail) {
+  bailoutHandlerOffset_ = startTrampolineCode(masm);
+
+  GenerateBailoutThunk(masm, NO_FRAME_SIZE_CLASS_ID, bailoutTail);
+}
+
+bool JitRuntime::generateVMWrapper(JSContext* cx, MacroAssembler& masm,
+                                   const VMFunctionData& f, DynFn nativeFun,
+                                   uint32_t* wrapperOffset) {
+  *wrapperOffset = startTrampolineCode(masm);
+
+  // Avoid conflicts with argument registers while discarding the result after
+  // the function call.
+  AllocatableGeneralRegisterSet regs(Register::Codes::WrapperMask);
+
+  static_assert(
+      (Register::Codes::VolatileMask & ~Register::Codes::WrapperMask) == 0,
+      "Wrapper register set should be a superset of Volatile register set.");
+
+  // The context is the first argument; a0 is the first argument register.
+  Register cxreg = a0;
+  regs.take(cxreg);
+
+  // If it isn't a tail call, then the return address needs to be saved
+  if (f.expectTailCall == NonTailCall) {
+    masm.pushReturnAddress();
+  }
+
+  // We're aligned to an exit frame, so link it up.
+  masm.loadJSContext(cxreg);
+  masm.enterExitFrame(cxreg, regs.getAny(), &f);
+
+  // Save the base of the argument set stored on the stack.
+  Register argsBase = InvalidReg;
+  if (f.explicitArgs) {
+    argsBase = t1;  // Use temporary register.
+    regs.take(argsBase);
+    masm.ma_addu(argsBase, StackPointer,
+                 Imm32(ExitFrameLayout::SizeWithFooter()));
+  }
+  uint32_t framePushedBeforeAlignStack = masm.framePushed();
+  masm.alignStackPointer();
+  masm.setFramePushed(0);
+
+  // Reserve space for the outparameter. Reserve sizeof(Value) for every
+  // case so that stack stays aligned.
+  uint32_t outParamSize = 0;
+  switch (f.outParam) {
+    case Type_Value:
+      outParamSize = sizeof(Value);
+      masm.reserveStack(outParamSize);
+      break;
+
+    case Type_Handle: {
+      uint32_t pushed = masm.framePushed();
+      masm.PushEmptyRooted(f.outParamRootType);
+      outParamSize = masm.framePushed() - pushed;
+    } break;
+
+    case Type_Bool:
+    case Type_Int32:
+      MOZ_ASSERT(sizeof(uintptr_t) == sizeof(uint32_t));
+      [[fallthrough]];
+    case Type_Pointer:
+      outParamSize = sizeof(uintptr_t);
+      masm.reserveStack(outParamSize);
+      break;
+
+    case Type_Double:
+      outParamSize = sizeof(double);
+      masm.reserveStack(outParamSize);
+      break;
+    default:
+      MOZ_ASSERT(f.outParam == Type_Void);
+      break;
+  }
+
+  uint32_t outParamOffset = 0;
+  if (f.outParam != Type_Void) {
+    // Make sure that stack is double aligned after outParam.
+    MOZ_ASSERT(outParamSize <= sizeof(double));
+    outParamOffset += sizeof(double) - outParamSize;
+  }
+  // Reserve stack for double sized args that are copied to be aligned.
+  outParamOffset += f.doubleByRefArgs() * sizeof(double);
+
+  Register doubleArgs = t0;
+  masm.reserveStack(outParamOffset);
+  masm.movePtr(StackPointer, doubleArgs);
+
+  if (!generateTLEnterVM(masm, f)) {
+    return false;
+  }
+
+  masm.setupAlignedABICall();
+  masm.passABIArg(cxreg);
+
+  size_t argDisp = 0;
+  size_t doubleArgDisp = 0;
+
+  // Copy any arguments.
+  for (uint32_t explicitArg = 0; explicitArg < f.explicitArgs; explicitArg++) {
+    switch (f.argProperties(explicitArg)) {
+      case VMFunctionData::WordByValue:
+        masm.passABIArg(MoveOperand(argsBase, argDisp), MoveOp::GENERAL);
+        argDisp += sizeof(uint32_t);
+        break;
+      case VMFunctionData::DoubleByValue:
+        // Values should be passed by reference, not by value, so we
+        // assert that the argument is a double-precision float.
+        MOZ_ASSERT(f.argPassedInFloatReg(explicitArg));
+        masm.passABIArg(MoveOperand(argsBase, argDisp), MoveOp::DOUBLE);
+        argDisp += sizeof(double);
+        break;
+      case VMFunctionData::WordByRef:
+        masm.passABIArg(
+            MoveOperand(argsBase, argDisp, MoveOperand::EFFECTIVE_ADDRESS),
+            MoveOp::GENERAL);
+        argDisp += sizeof(uint32_t);
+        break;
+      case VMFunctionData::DoubleByRef:
+        // Copy double sized argument to aligned place.
+        masm.ma_ldc1WordAligned(ScratchDoubleReg, argsBase, argDisp);
+        masm.as_sdc1(ScratchDoubleReg, doubleArgs, doubleArgDisp);
+        masm.passABIArg(MoveOperand(doubleArgs, doubleArgDisp,
+                                    MoveOperand::EFFECTIVE_ADDRESS),
+                        MoveOp::GENERAL);
+        doubleArgDisp += sizeof(double);
+        argDisp += sizeof(double);
+        break;
+    }
+  }
+
+  MOZ_ASSERT_IF(f.outParam != Type_Void, doubleArgDisp + sizeof(double) ==
+                                             outParamOffset + outParamSize);
+
+  // Copy the implicit outparam, if any.
+  if (f.outParam != Type_Void) {
+    masm.passABIArg(
+        MoveOperand(doubleArgs, outParamOffset, MoveOperand::EFFECTIVE_ADDRESS),
+        MoveOp::GENERAL);
+  }
+
+  masm.callWithABI(nativeFun, MoveOp::GENERAL,
+                   CheckUnsafeCallWithABI::DontCheckHasExitFrame);
+
+  if (!generateTLExitVM(masm, f)) {
+    return false;
+  }
+
+  // Test for failure.
+  switch (f.failType()) {
+    case Type_Object:
+      masm.branchTestPtr(Assembler::Zero, v0, v0, masm.failureLabel());
+      break;
+    case Type_Bool:
+      // Called functions return bools, which are 0/false and non-zero/true
+      masm.branchIfFalseBool(v0, masm.failureLabel());
+      break;
+    case Type_Void:
+      break;
+    default:
+      MOZ_CRASH("unknown failure kind");
+  }
+
+  masm.freeStack(outParamOffset);
+
+  // Load the outparam and free any allocated stack.
+  switch (f.outParam) {
+    case Type_Handle:
+      masm.popRooted(f.outParamRootType, ReturnReg, JSReturnOperand);
+      break;
+
+    case Type_Value:
+      masm.loadValue(Address(StackPointer, 0), JSReturnOperand);
+      masm.freeStack(sizeof(Value));
+      break;
+
+    case Type_Int32:
+      MOZ_ASSERT(sizeof(uintptr_t) == sizeof(uint32_t));
+      [[fallthrough]];
+    case Type_Pointer:
+      masm.load32(Address(StackPointer, 0), ReturnReg);
+      masm.freeStack(sizeof(uintptr_t));
+      break;
+
+    case Type_Bool:
+      masm.load8ZeroExtend(Address(StackPointer, 0), ReturnReg);
+      masm.freeStack(sizeof(uintptr_t));
+      break;
+
+    case Type_Double:
+      if (JitOptions.supportsFloatingPoint) {
+        masm.as_ldc1(ReturnDoubleReg, StackPointer, 0);
+      } else {
+        masm.assumeUnreachable(
+            "Unable to load into float reg, with no FP support.");
+      }
+      masm.freeStack(sizeof(double));
+      break;
+
+    default:
+      MOZ_ASSERT(f.outParam == Type_Void);
+      break;
+  }
+
+  masm.restoreStackPointer();
+  masm.setFramePushed(framePushedBeforeAlignStack);
+
+  masm.leaveExitFrame();
+  masm.retn(Imm32(sizeof(ExitFrameLayout) +
+                  f.explicitStackSlots() * sizeof(uintptr_t) +
+                  f.extraValuesToPop * sizeof(Value)));
+
+  return true;
+}
+
+uint32_t JitRuntime::generatePreBarrier(JSContext* cx, MacroAssembler& masm,
+                                        MIRType type) {
+  uint32_t offset = startTrampolineCode(masm);
+
+  MOZ_ASSERT(PreBarrierReg == a1);
+  Register temp1 = a0;
+  Register temp2 = a2;
+  Register temp3 = a3;
+  masm.push(temp1);
+  masm.push(temp2);
+  masm.push(temp3);
+
+  Label noBarrier;
+  masm.emitPreBarrierFastPath(cx->runtime(), type, temp1, temp2, temp3,
+                              &noBarrier);
+
+  // Call into C++ to mark this GC thing.
+  masm.pop(temp3);
+  masm.pop(temp2);
+  masm.pop(temp1);
+
+  LiveRegisterSet save;
+  if (JitOptions.supportsFloatingPoint) {
+    save.set() = RegisterSet(GeneralRegisterSet(Registers::VolatileMask),
+                             FloatRegisterSet(FloatRegisters::VolatileMask));
+  } else {
+    save.set() = RegisterSet(GeneralRegisterSet(Registers::VolatileMask),
+                             FloatRegisterSet());
+  }
+  save.add(ra);
+  masm.PushRegsInMask(save);
+
+  masm.movePtr(ImmPtr(cx->runtime()), a0);
+
+  masm.setupUnalignedABICall(a2);
+  masm.passABIArg(a0);
+  masm.passABIArg(a1);
+  masm.callWithABI(JitMarkFunction(type));
+
+  save.take(AnyRegister(ra));
+  masm.PopRegsInMask(save);
+  masm.ret();
+
+  masm.bind(&noBarrier);
+  masm.pop(temp3);
+  masm.pop(temp2);
+  masm.pop(temp1);
+  masm.abiret();
+
+  return offset;
+}
+
+void JitRuntime::generateExceptionTailStub(MacroAssembler& masm,
+                                           Label* profilerExitTail) {
+  exceptionTailOffset_ = startTrampolineCode(masm);
+
+  masm.bind(masm.failureLabel());
+  masm.handleFailureWithHandlerTail(profilerExitTail);
+}
+
+void JitRuntime::generateBailoutTailStub(MacroAssembler& masm,
+                                         Label* bailoutTail) {
+  bailoutTailOffset_ = startTrampolineCode(masm);
+  masm.bind(bailoutTail);
+
+  masm.generateBailoutTail(a1, a2);
+}
+
+void JitRuntime::generateProfilerExitFrameTailStub(MacroAssembler& masm,
+                                                   Label* profilerExitTail) {
+  profilerExitFrameTailOffset_ = startTrampolineCode(masm);
+  masm.bind(profilerExitTail);
+
+  Register scratch1 = t0;
+  Register scratch2 = t1;
+  Register scratch3 = t2;
+  Register scratch4 = t3;
+
+  //
+  // The code generated below expects that the current stack pointer points
+  // to an Ion or Baseline frame, at the state it would be immediately
+  // before a ret().  Thus, after this stub's business is done, it executes
+  // a ret() and returns directly to the caller script, on behalf of the
+  // callee script that jumped to this code.
+  //
+  // Thus the expected stack is:
+  //
+  //                                   StackPointer ----+
+  //                                                    v
+  // ..., ActualArgc, CalleeToken, Descriptor, ReturnAddr
+  // MEM-HI                                       MEM-LOW
+  //
+  //
+  // The generated jitcode is responsible for overwriting the
+  // jitActivation->lastProfilingFrame field with a pointer to the previous
+  // Ion or Baseline jit-frame that was pushed before this one. It is also
+  // responsible for overwriting jitActivation->lastProfilingCallSite with
+  // the return address into that frame.  The frame could either be an
+  // immediate "caller" frame, or it could be a frame in a previous
+  // JitActivation (if the current frame was entered from C++, and the C++
+  // was entered by some caller jit-frame further down the stack).
+  //
+  // So this jitcode is responsible for "walking up" the jit stack, finding
+  // the previous Ion or Baseline JS frame, and storing its address and the
+  // return address into the appropriate fields on the current jitActivation.
+  //
+  // There are a fixed number of different path types that can lead to the
+  // current frame, which is either a baseline or ion frame:
+  //
+  // <Baseline-Or-Ion>
+  // ^
+  // |
+  // ^--- Ion
+  // |
+  // ^--- Baseline Stub <---- Baseline
+  // |
+  // ^--- Argument Rectifier
+  // |    ^
+  // |    |
+  // |    ^--- Ion
+  // |    |
+  // |    ^--- Baseline Stub <---- Baseline
+  // |
+  // ^--- Entry Frame (From C++)
+  //
+  Register actReg = scratch4;
+  masm.loadJSContext(actReg);
+  masm.loadPtr(Address(actReg, offsetof(JSContext, profilingActivation_)),
+               actReg);
+
+  Address lastProfilingFrame(actReg,
+                             JitActivation::offsetOfLastProfilingFrame());
+  Address lastProfilingCallSite(actReg,
+                                JitActivation::offsetOfLastProfilingCallSite());
+
+#ifdef DEBUG
+  // Ensure that frame we are exiting is current lastProfilingFrame
+  {
+    masm.loadPtr(lastProfilingFrame, scratch1);
+    Label checkOk;
+    masm.branchPtr(Assembler::Equal, scratch1, ImmWord(0), &checkOk);
+    masm.branchPtr(Assembler::Equal, StackPointer, scratch1, &checkOk);
+    masm.assumeUnreachable(
+        "Mismatch between stored lastProfilingFrame and current stack "
+        "pointer.");
+    masm.bind(&checkOk);
+  }
+#endif
+
+  // Load the frame descriptor into |scratch1|, figure out what to do depending
+  // on its type.
+  masm.loadPtr(Address(StackPointer, JitFrameLayout::offsetOfDescriptor()),
+               scratch1);
+
+  // Going into the conditionals, we will have:
+  //      FrameDescriptor.size in scratch1
+  //      FrameDescriptor.type in scratch2
+  masm.ma_and(scratch2, scratch1, Imm32((1 << FRAMETYPE_BITS) - 1));
+  masm.rshiftPtr(Imm32(FRAMESIZE_SHIFT), scratch1);
+
+  // Handling of each case is dependent on FrameDescriptor.type
+  Label handle_IonJS;
+  Label handle_BaselineStub;
+  Label handle_Rectifier;
+  Label handle_IonICCall;
+  Label handle_Entry;
+  Label end;
+
+  masm.branch32(Assembler::Equal, scratch2, Imm32(FrameType::IonJS),
+                &handle_IonJS);
+  masm.branch32(Assembler::Equal, scratch2, Imm32(FrameType::BaselineJS),
+                &handle_IonJS);
+  masm.branch32(Assembler::Equal, scratch2, Imm32(FrameType::BaselineStub),
+                &handle_BaselineStub);
+  masm.branch32(Assembler::Equal, scratch2, Imm32(FrameType::Rectifier),
+                &handle_Rectifier);
+  masm.branch32(Assembler::Equal, scratch2, Imm32(FrameType::IonICCall),
+                &handle_IonICCall);
+  masm.branch32(Assembler::Equal, scratch2, Imm32(FrameType::CppToJSJit),
+                &handle_Entry);
+
+  // The WasmToJSJit is just another kind of entry.
+  masm.branch32(Assembler::Equal, scratch2, Imm32(FrameType::WasmToJSJit),
+                &handle_Entry);
+
+  masm.assumeUnreachable(
+      "Invalid caller frame type when exiting from Ion frame.");
+
+  //
+  // FrameType::IonJS
+  //
+  // Stack layout:
+  //                  ...
+  //                  Ion-Descriptor
+  //     Prev-FP ---> Ion-ReturnAddr
+  //                  ... previous frame data ... |- Descriptor.Size
+  //                  ... arguments ...           |
+  //                  ActualArgc          |
+  //                  CalleeToken         |- JitFrameLayout::Size()
+  //                  Descriptor          |
+  //        FP -----> ReturnAddr          |
+  //
+  masm.bind(&handle_IonJS);
+  {
+    // |scratch1| contains Descriptor.size
+
+    // returning directly to an IonJS frame.  Store return addr to frame
+    // in lastProfilingCallSite.
+    masm.loadPtr(Address(StackPointer, JitFrameLayout::offsetOfReturnAddress()),
+                 scratch2);
+    masm.storePtr(scratch2, lastProfilingCallSite);
+
+    // Store return frame in lastProfilingFrame.
+    // scratch2 := StackPointer + Descriptor.size*1 + JitFrameLayout::Size();
+    masm.as_addu(scratch2, StackPointer, scratch1);
+    masm.ma_addu(scratch2, scratch2, Imm32(JitFrameLayout::Size()));
+    masm.storePtr(scratch2, lastProfilingFrame);
+    masm.ret();
+  }
+
+  //
+  // FrameType::BaselineStub
+  //
+  // Look past the stub and store the frame pointer to
+  // the baselineJS frame prior to it.
+  //
+  // Stack layout:
+  //              ...
+  //              BL-Descriptor
+  // Prev-FP ---> BL-ReturnAddr
+  //      +-----> BL-PrevFramePointer
+  //      |       ... BL-FrameData ...
+  //      |       BLStub-Descriptor
+  //      |       BLStub-ReturnAddr
+  //      |       BLStub-StubPointer          |
+  //      +------ BLStub-SavedFramePointer    |- Descriptor.Size
+  //              ... arguments ...           |
+  //              ActualArgc          |
+  //              CalleeToken         |- JitFrameLayout::Size()
+  //              Descriptor          |
+  //    FP -----> ReturnAddr          |
+  //
+  // We take advantage of the fact that the stub frame saves the frame
+  // pointer pointing to the baseline frame, so a bunch of calculation can
+  // be avoided.
+  //
+  masm.bind(&handle_BaselineStub);
+  {
+    masm.as_addu(scratch3, StackPointer, scratch1);
+    Address stubFrameReturnAddr(
+        scratch3, JitFrameLayout::Size() +
+                      BaselineStubFrameLayout::offsetOfReturnAddress());
+    masm.loadPtr(stubFrameReturnAddr, scratch2);
+    masm.storePtr(scratch2, lastProfilingCallSite);
+
+    Address stubFrameSavedFramePtr(
+        scratch3, JitFrameLayout::Size() - (2 * sizeof(void*)));
+    masm.loadPtr(stubFrameSavedFramePtr, scratch2);
+    masm.addPtr(Imm32(sizeof(void*)), scratch2);  // Skip past BL-PrevFramePtr
+    masm.storePtr(scratch2, lastProfilingFrame);
+    masm.ret();
+  }
+
+  //
+  // FrameType::Rectifier
+  //
+  // The rectifier frame can be preceded by either an IonJS, a BaselineStub,
+  // or a CppToJSJit/WasmToJSJit frame.
+  //
+  // Stack layout if caller of rectifier was Ion or CppToJSJit/WasmToJSJit:
+  //
+  //              Ion-Descriptor
+  //              Ion-ReturnAddr
+  //              ... ion frame data ... |- Rect-Descriptor.Size
+  //              < COMMON LAYOUT >
+  //
+  // Stack layout if caller of rectifier was Baseline:
+  //
+  //              BL-Descriptor
+  // Prev-FP ---> BL-ReturnAddr
+  //      +-----> BL-SavedFramePointer
+  //      |       ... baseline frame data ...
+  //      |       BLStub-Descriptor
+  //      |       BLStub-ReturnAddr
+  //      |       BLStub-StubPointer          |
+  //      +------ BLStub-SavedFramePointer    |- Rect-Descriptor.Size
+  //              ... args to rectifier ...   |
+  //              < COMMON LAYOUT >
+  //
+  // Common stack layout:
+  //
+  //              ActualArgc          |
+  //              CalleeToken         |- IonRectitiferFrameLayout::Size()
+  //              Rect-Descriptor     |
+  //              Rect-ReturnAddr     |
+  //              ... rectifier data & args ... |- Descriptor.Size
+  //              ActualArgc      |
+  //              CalleeToken     |- JitFrameLayout::Size()
+  //              Descriptor      |
+  //    FP -----> ReturnAddr      |
+  //
+  masm.bind(&handle_Rectifier);
+  {
+    // scratch2 := StackPointer + Descriptor.size*1 + JitFrameLayout::Size();
+    masm.as_addu(scratch2, StackPointer, scratch1);
+    masm.add32(Imm32(JitFrameLayout::Size()), scratch2);
+    masm.loadPtr(Address(scratch2, RectifierFrameLayout::offsetOfDescriptor()),
+                 scratch3);
+    masm.ma_srl(scratch1, scratch3, Imm32(FRAMESIZE_SHIFT));
+    masm.and32(Imm32((1 << FRAMETYPE_BITS) - 1), scratch3);
+
+    // Now |scratch1| contains Rect-Descriptor.Size
+    // and |scratch2| points to Rectifier frame
+    // and |scratch3| contains Rect-Descriptor.Type
+
+    masm.assertRectifierFrameParentType(scratch3);
+
+    // Check for either Ion or BaselineStub frame.
+    Label notIonFrame;
+    masm.branch32(Assembler::NotEqual, scratch3, Imm32(FrameType::IonJS),
+                  &notIonFrame);
+
+    // Handle Rectifier <- IonJS
+    // scratch3 := RectFrame[ReturnAddr]
+    masm.loadPtr(
+        Address(scratch2, RectifierFrameLayout::offsetOfReturnAddress()),
+        scratch3);
+    masm.storePtr(scratch3, lastProfilingCallSite);
+
+    // scratch3 := RectFrame + Rect-Descriptor.Size +
+    //             RectifierFrameLayout::Size()
+    masm.as_addu(scratch3, scratch2, scratch1);
+    masm.add32(Imm32(RectifierFrameLayout::Size()), scratch3);
+    masm.storePtr(scratch3, lastProfilingFrame);
+    masm.ret();
+
+    masm.bind(&notIonFrame);
+
+    // Check for either BaselineStub or a CppToJSJit/WasmToJSJit entry
+    // frame.
+    masm.branch32(Assembler::NotEqual, scratch3, Imm32(FrameType::BaselineStub),
+                  &handle_Entry);
+
+    // Handle Rectifier <- BaselineStub <- BaselineJS
+    masm.as_addu(scratch3, scratch2, scratch1);
+    Address stubFrameReturnAddr(
+        scratch3, RectifierFrameLayout::Size() +
+                      BaselineStubFrameLayout::offsetOfReturnAddress());
+    masm.loadPtr(stubFrameReturnAddr, scratch2);
+    masm.storePtr(scratch2, lastProfilingCallSite);
+
+    Address stubFrameSavedFramePtr(
+        scratch3, RectifierFrameLayout::Size() - (2 * sizeof(void*)));
+    masm.loadPtr(stubFrameSavedFramePtr, scratch2);
+    masm.addPtr(Imm32(sizeof(void*)), scratch2);
+    masm.storePtr(scratch2, lastProfilingFrame);
+    masm.ret();
+  }
+
+  // FrameType::IonICCall
+  //
+  // The caller is always an IonJS frame.
+  //
+  //              Ion-Descriptor
+  //              Ion-ReturnAddr
+  //              ... ion frame data ... |- CallFrame-Descriptor.Size
+  //              StubCode               |
+  //              ICCallFrame-Descriptor |- IonICCallFrameLayout::Size()
+  //              ICCallFrame-ReturnAddr |
+  //              ... call frame data & args ... |- Descriptor.Size
+  //              ActualArgc      |
+  //              CalleeToken     |- JitFrameLayout::Size()
+  //              Descriptor      |
+  //    FP -----> ReturnAddr      |
+  masm.bind(&handle_IonICCall);
+  {
+    // scratch2 := StackPointer + Descriptor.size + JitFrameLayout::Size()
+    masm.as_addu(scratch2, StackPointer, scratch1);
+    masm.addPtr(Imm32(JitFrameLayout::Size()), scratch2);
+
+    // scratch3 := ICCallFrame-Descriptor.Size
+    masm.loadPtr(Address(scratch2, IonICCallFrameLayout::offsetOfDescriptor()),
+                 scratch3);
+#ifdef DEBUG
+    // Assert previous frame is an IonJS frame.
+    masm.movePtr(scratch3, scratch1);
+    masm.and32(Imm32((1 << FRAMETYPE_BITS) - 1), scratch1);
+    {
+      Label checkOk;
+      masm.branch32(Assembler::Equal, scratch1, Imm32(FrameType::IonJS),
+                    &checkOk);
+      masm.assumeUnreachable("IonICCall frame must be preceded by IonJS frame");
+      masm.bind(&checkOk);
+    }
+#endif
+    masm.rshiftPtr(Imm32(FRAMESIZE_SHIFT), scratch3);
+
+    // lastProfilingCallSite := ICCallFrame-ReturnAddr
+    masm.loadPtr(
+        Address(scratch2, IonICCallFrameLayout::offsetOfReturnAddress()),
+        scratch1);
+    masm.storePtr(scratch1, lastProfilingCallSite);
+
+    // lastProfilingFrame := ICCallFrame + ICCallFrame-Descriptor.Size +
+    //                       IonICCallFrameLayout::Size()
+    masm.as_addu(scratch1, scratch2, scratch3);
+    masm.addPtr(Imm32(IonICCallFrameLayout::Size()), scratch1);
+    masm.storePtr(scratch1, lastProfilingFrame);
+    masm.ret();
+  }
+
+  //
+  // FrameType::CppToJSJit / FrameType::WasmToJSJit
+  //
+  // If at an entry frame, store null into both fields.
+  // A fast-path wasm->jit transition frame is an entry frame from the point
+  // of view of the JIT.
+  //
+  masm.bind(&handle_Entry);
+  {
+    masm.movePtr(ImmPtr(nullptr), scratch1);
+    masm.storePtr(scratch1, lastProfilingCallSite);
+    masm.storePtr(scratch1, lastProfilingFrame);
+    masm.ret();
+  }
+}