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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ *
+ * Copyright 2015 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef wasm_stubs_h
+#define wasm_stubs_h
+
+#include "wasm/WasmFrameIter.h" // js::wasm::ExitReason
+#include "wasm/WasmGenerator.h"
+#include "wasm/WasmOpIter.h"
+
+namespace js {
+namespace wasm {
+
+using jit::FloatRegister;
+using jit::Register;
+using jit::Register64;
+
+// ValType and location for a single result: either in a register or on the
+// stack.
+
+class ABIResult {
+ ValType type_;
+ enum class Location { Gpr, Gpr64, Fpr, Stack } loc_;
+ union {
+ Register gpr_;
+ Register64 gpr64_;
+ FloatRegister fpr_;
+ uint32_t stackOffset_;
+ };
+
+ void validate() {
+#ifdef DEBUG
+ if (onStack()) {
+ return;
+ }
+ MOZ_ASSERT(inRegister());
+ switch (type_.kind()) {
+ case ValType::I32:
+ MOZ_ASSERT(loc_ == Location::Gpr);
+ break;
+ case ValType::I64:
+ MOZ_ASSERT(loc_ == Location::Gpr64);
+ break;
+ case ValType::F32:
+ case ValType::F64:
+ MOZ_ASSERT(loc_ == Location::Fpr);
+ break;
+ case ValType::Ref:
+ MOZ_ASSERT(loc_ == Location::Gpr);
+ break;
+ case ValType::V128:
+ MOZ_ASSERT(loc_ == Location::Fpr);
+ break;
+ }
+#endif
+ }
+
+ friend class ABIResultIter;
+ ABIResult() {}
+
+ public:
+ // Sizes of items in the stack area.
+ //
+ // The size values come from the implementations of Push() in
+ // MacroAssembler-x86-shared.cpp and MacroAssembler-arm-shared.cpp, and from
+ // VFPRegister::size() in Architecture-arm.h.
+ //
+ // On ARM unlike on x86 we push a single for float.
+
+ static constexpr size_t StackSizeOfPtr = sizeof(intptr_t);
+ static constexpr size_t StackSizeOfInt32 = StackSizeOfPtr;
+ static constexpr size_t StackSizeOfInt64 = sizeof(int64_t);
+#if defined(JS_CODEGEN_ARM)
+ static constexpr size_t StackSizeOfFloat = sizeof(float);
+#else
+ static constexpr size_t StackSizeOfFloat = sizeof(double);
+#endif
+ static constexpr size_t StackSizeOfDouble = sizeof(double);
+#ifdef ENABLE_WASM_SIMD
+ static constexpr size_t StackSizeOfV128 = sizeof(V128);
+#endif
+
+ ABIResult(ValType type, Register gpr)
+ : type_(type), loc_(Location::Gpr), gpr_(gpr) {
+ validate();
+ }
+ ABIResult(ValType type, Register64 gpr64)
+ : type_(type), loc_(Location::Gpr64), gpr64_(gpr64) {
+ validate();
+ }
+ ABIResult(ValType type, FloatRegister fpr)
+ : type_(type), loc_(Location::Fpr), fpr_(fpr) {
+ validate();
+ }
+ ABIResult(ValType type, uint32_t stackOffset)
+ : type_(type), loc_(Location::Stack), stackOffset_(stackOffset) {
+ validate();
+ }
+
+ ValType type() const { return type_; }
+ bool onStack() const { return loc_ == Location::Stack; }
+ bool inRegister() const { return !onStack(); }
+ Register gpr() const {
+ MOZ_ASSERT(loc_ == Location::Gpr);
+ return gpr_;
+ }
+ Register64 gpr64() const {
+ MOZ_ASSERT(loc_ == Location::Gpr64);
+ return gpr64_;
+ }
+ FloatRegister fpr() const {
+ MOZ_ASSERT(loc_ == Location::Fpr);
+ return fpr_;
+ }
+ // Offset from SP.
+ uint32_t stackOffset() const {
+ MOZ_ASSERT(loc_ == Location::Stack);
+ return stackOffset_;
+ }
+ uint32_t size() const;
+};
+
+// Just as WebAssembly functions can take multiple arguments, they can also
+// return multiple results. As with a call, a limited number of results will be
+// located in registers, and the rest will be stored in a stack area. The
+// |ABIResultIter| computes result locations, given a |ResultType|.
+//
+// Recall that a |ResultType| represents a sequence of value types t1..tN,
+// indexed from 1 to N. In principle it doesn't matter how we decide which
+// results get to be in registers and which go to the stack. To better
+// harmonize with WebAssembly's abstract stack machine, whose properties are
+// taken advantage of by the baseline compiler, our strategy is to start
+// allocating result locations in "reverse" order: from result N down to 1.
+//
+// If a result with index I is in a register, then all results with index J > I
+// are also in registers. If a result I is on the stack, then all results with
+// index K < I are also on the stack, farther away from the stack pointer than
+// result I.
+//
+// Currently only a single result is ever stored in a register, though this may
+// change in the future on register-rich platforms.
+//
+// NB: The baseline compiler also uses thie ABI for locations of block
+// parameters and return values, within individual WebAssembly functions.
+
+class ABIResultIter {
+ ResultType type_;
+ uint32_t count_;
+ uint32_t index_;
+ uint32_t nextStackOffset_;
+ enum { Next, Prev } direction_;
+ ABIResult cur_;
+
+ void settleRegister(ValType type);
+ void settleNext();
+ void settlePrev();
+
+ public:
+ explicit ABIResultIter(const ResultType& type)
+ : type_(type), count_(type.length()) {
+ reset();
+ }
+
+ void reset() {
+ index_ = nextStackOffset_ = 0;
+ direction_ = Next;
+ if (!done()) {
+ settleNext();
+ }
+ }
+ bool done() const { return index_ == count_; }
+ uint32_t index() const { return index_; }
+ uint32_t count() const { return count_; }
+ uint32_t remaining() const { return count_ - index_; }
+ void switchToNext() {
+ MOZ_ASSERT(direction_ == Prev);
+ if (!done() && cur().onStack()) {
+ nextStackOffset_ += cur().size();
+ }
+ index_ = count_ - index_;
+ direction_ = Next;
+ if (!done()) {
+ settleNext();
+ }
+ }
+ void switchToPrev() {
+ MOZ_ASSERT(direction_ == Next);
+ if (!done() && cur().onStack()) {
+ nextStackOffset_ -= cur().size();
+ }
+ index_ = count_ - index_;
+ direction_ = Prev;
+ if (!done()) settlePrev();
+ }
+ void next() {
+ MOZ_ASSERT(direction_ == Next);
+ MOZ_ASSERT(!done());
+ index_++;
+ if (!done()) {
+ settleNext();
+ }
+ }
+ void prev() {
+ MOZ_ASSERT(direction_ == Prev);
+ MOZ_ASSERT(!done());
+ index_++;
+ if (!done()) {
+ settlePrev();
+ }
+ }
+ const ABIResult& cur() const {
+ MOZ_ASSERT(!done());
+ return cur_;
+ }
+
+ uint32_t stackBytesConsumedSoFar() const { return nextStackOffset_; }
+
+ static inline bool HasStackResults(const ResultType& type) {
+ return type.length() > MaxRegisterResults;
+ }
+
+ static uint32_t MeasureStackBytes(const ResultType& type) {
+ if (!HasStackResults(type)) {
+ return 0;
+ }
+ ABIResultIter iter(type);
+ while (!iter.done()) {
+ iter.next();
+ }
+ return iter.stackBytesConsumedSoFar();
+ }
+};
+
+extern bool GenerateBuiltinThunk(jit::MacroAssembler& masm,
+ jit::ABIFunctionType abiType,
+ ExitReason exitReason, void* funcPtr,
+ CallableOffsets* offsets);
+
+extern bool GenerateImportFunctions(const ModuleEnvironment& env,
+ const FuncImportVector& imports,
+ CompiledCode* code);
+
+extern bool GenerateStubs(const ModuleEnvironment& env,
+ const FuncImportVector& imports,
+ const FuncExportVector& exports, CompiledCode* code);
+
+extern bool GenerateEntryStubs(jit::MacroAssembler& masm,
+ size_t funcExportIndex, const FuncExport& fe,
+ const FuncType& funcType,
+ const Maybe<jit::ImmPtr>& callee, bool isAsmJS,
+ CodeRangeVector* codeRanges);
+
+extern void GenerateTrapExitRegisterOffsets(jit::RegisterOffsets* offsets,
+ size_t* numWords);
+
+extern bool GenerateProvisionalLazyJitEntryStub(jit::MacroAssembler& masm,
+ Offsets* offsets);
+
+// A value that is written into the trap exit frame, which is useful for
+// cross-checking during garbage collection.
+static constexpr uintptr_t TrapExitDummyValue = 1337;
+
+// And its offset, in words, down from the highest-addressed word of the trap
+// exit frame. The value is written into the frame using WasmPush. In the
+// case where WasmPush allocates more than one word, the value will therefore
+// be written at the lowest-addressed word.
+#ifdef JS_CODEGEN_ARM64
+static constexpr size_t TrapExitDummyValueOffsetFromTop = 1;
+#else
+static constexpr size_t TrapExitDummyValueOffsetFromTop = 0;
+#endif
+
+// An argument that will end up on the stack according to the system ABI, to be
+// passed to GenerateDirectCallFromJit. Since the direct JIT call creates its
+// own frame, it is its responsibility to put stack arguments to their expected
+// locations; so the caller of GenerateDirectCallFromJit can put them anywhere.
+
+class JitCallStackArg {
+ public:
+ enum class Tag {
+ Imm32,
+ GPR,
+ FPU,
+ Address,
+ Undefined,
+ };
+
+ private:
+ Tag tag_;
+ union U {
+ int32_t imm32_;
+ jit::Register gpr_;
+ jit::FloatRegister fpu_;
+ jit::Address addr_;
+ U() {}
+ } arg;
+
+ public:
+ JitCallStackArg() : tag_(Tag::Undefined) {}
+ explicit JitCallStackArg(int32_t imm32) : tag_(Tag::Imm32) {
+ arg.imm32_ = imm32;
+ }
+ explicit JitCallStackArg(jit::Register gpr) : tag_(Tag::GPR) {
+ arg.gpr_ = gpr;
+ }
+ explicit JitCallStackArg(jit::FloatRegister fpu) : tag_(Tag::FPU) {
+ new (&arg) jit::FloatRegister(fpu);
+ }
+ explicit JitCallStackArg(const jit::Address& addr) : tag_(Tag::Address) {
+ new (&arg) jit::Address(addr);
+ }
+
+ Tag tag() const { return tag_; }
+ int32_t imm32() const {
+ MOZ_ASSERT(tag_ == Tag::Imm32);
+ return arg.imm32_;
+ }
+ jit::Register gpr() const {
+ MOZ_ASSERT(tag_ == Tag::GPR);
+ return arg.gpr_;
+ }
+ jit::FloatRegister fpu() const {
+ MOZ_ASSERT(tag_ == Tag::FPU);
+ return arg.fpu_;
+ }
+ const jit::Address& addr() const {
+ MOZ_ASSERT(tag_ == Tag::Address);
+ return arg.addr_;
+ }
+};
+
+using JitCallStackArgVector = Vector<JitCallStackArg, 4, SystemAllocPolicy>;
+
+// Generates an inline wasm call (during jit compilation) to a specific wasm
+// function (as specifed by the given FuncExport).
+// This call doesn't go through a wasm entry, but rather creates its own
+// inlined exit frame.
+// Assumes:
+// - all the registers have been preserved by the caller,
+// - all arguments passed in registers have been set up at the expected
+// locations,
+// - all arguments passed on stack slot are alive as defined by a corresponding
+// JitCallStackArg.
+
+extern void GenerateDirectCallFromJit(jit::MacroAssembler& masm,
+ const FuncExport& fe,
+ const Instance& inst,
+ const JitCallStackArgVector& stackArgs,
+ jit::Register scratch,
+ uint32_t* callOffset);
+
+} // namespace wasm
+} // namespace js
+
+#endif // wasm_stubs_h