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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:
* 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 */
#ifndef jit_MachineState_h
#define jit_MachineState_h
#include "mozilla/Assertions.h"
#include "mozilla/Attributes.h"
#include "mozilla/Variant.h"
#include <stdint.h>
#include "jit/Registers.h"
#include "jit/RegisterSets.h"
namespace js::jit {
// Information needed to recover machine register state. This supports two
// different modes:
// * Bailouts: all registers are pushed on the stack as part of the bailout
// process, so MachineState simply points to these FPU/GPR arrays.
// See RegisterDump and BailoutStack.
// * Safepoints: live registers are pushed on the stack before a VM call, so
// MachineState stores the register sets and a pointer to the stack memory
// where these registers were pushed. This is also used by exception bailouts.
class MOZ_STACK_CLASS MachineState {
struct NullState {};
struct BailoutState {
RegisterDump::FPUArray& floatRegs;
RegisterDump::GPRArray& regs;
BailoutState(RegisterDump::FPUArray& floatRegs,
RegisterDump::GPRArray& regs)
: floatRegs(floatRegs), regs(regs) {}
struct SafepointState {
FloatRegisterSet floatRegs;
GeneralRegisterSet regs;
// Pointers to the start of the pushed |floatRegs| and |regs| on the stack.
// This is the value of the stack pointer right before the first register
// was pushed.
char* floatSpillBase;
uintptr_t* spillBase;
SafepointState(const FloatRegisterSet& floatRegs,
const GeneralRegisterSet& regs, char* floatSpillBase,
uintptr_t* spillBase)
: floatRegs(floatRegs),
spillBase(spillBase) {}
uintptr_t* addressOfRegister(Register reg) const;
char* addressOfRegister(FloatRegister reg) const;
using State = mozilla::Variant<NullState, BailoutState, SafepointState>;
State state_{NullState()};
MachineState() = default;
MachineState(const MachineState& other) = default;
MachineState& operator=(const MachineState& other) = default;
static MachineState FromBailout(RegisterDump::GPRArray& regs,
RegisterDump::FPUArray& fpregs) {
MachineState res;
res.state_.emplace<BailoutState>(fpregs, regs);
return res;
static MachineState FromSafepoint(const FloatRegisterSet& floatRegs,
const GeneralRegisterSet& regs,
char* floatSpillBase,
uintptr_t* spillBase) {
MachineState res;
res.state_.emplace<SafepointState>(floatRegs, regs, floatSpillBase,
return res;
bool has(Register reg) const {
if (<BailoutState>()) {
return true;
bool has(FloatRegister reg) const {
if (<BailoutState>()) {
return true;
uintptr_t read(Register reg) const;
template <typename T>
T read(FloatRegister reg) const;
// Used by moving GCs to update pointers.
void write(Register reg, uintptr_t value) const;
} // namespace js::jit
#endif /* jit_MachineState_h */