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Diffstat (limited to 'js/src/wasm/WasmStubs.h')
| -rw-r--r-- | js/src/wasm/WasmStubs.h | 370 |
1 files changed, 370 insertions, 0 deletions
diff --git a/js/src/wasm/WasmStubs.h b/js/src/wasm/WasmStubs.h new file mode 100644 index 0000000000..6a6622fdf2 --- /dev/null +++ b/js/src/wasm/WasmStubs.h @@ -0,0 +1,370 @@ +/* -*- 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 |