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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
#include "jit/arm/SharedICHelpers-arm.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/PerfSpewer.h"
#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 const FloatRegisterSet NonVolatileFloatRegs = FloatRegisterSet(
(1ULL << FloatRegisters::d8) | (1ULL << FloatRegisters::d9) |
(1ULL << FloatRegisters::d10) | (1ULL << FloatRegisters::d11) |
(1ULL << FloatRegisters::d12) | (1ULL << FloatRegisters::d13) |
(1ULL << FloatRegisters::d14) | (1ULL << FloatRegisters::d15));
static void GenerateReturn(MacroAssembler& masm, int returnCode) {
// Restore non-volatile floating point registers.
masm.transferMultipleByRuns(NonVolatileFloatRegs, IsLoad, StackPointer, IA);
// Get rid of padding word.
masm.addPtr(Imm32(sizeof(void*)), sp);
// Set up return value
masm.ma_mov(Imm32(returnCode), r0);
// Pop and return
masm.startDataTransferM(IsLoad, sp, IA, WriteBack);
masm.transferReg(r4);
masm.transferReg(r5);
masm.transferReg(r6);
masm.transferReg(r7);
masm.transferReg(r8);
masm.transferReg(r9);
masm.transferReg(r10);
masm.transferReg(r11);
// r12 isn't saved, so it shouldn't be restored.
masm.transferReg(pc);
masm.finishDataTransfer();
masm.flushBuffer();
}
struct EnterJITStack {
double d8;
double d9;
double d10;
double d11;
double d12;
double d13;
double d14;
double d15;
// Padding.
void* padding;
// Non-volatile registers.
void* r4;
void* r5;
void* r6;
void* r7;
void* r8;
void* r9;
void* r10;
void* r11;
// The abi does not expect r12 (ip) to be preserved
void* lr;
// Arguments.
// code == r0
// argc == r1
// argv == r2
// frame == r3
CalleeToken token;
JSObject* scopeChain;
size_t numStackValues;
Value* vp;
};
/*
* 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) {
AutoCreatedBy acb(masm, "JitRuntime::generateEnterJIT");
enterJITOffset_ = startTrampolineCode(masm);
const Address slot_token(sp, offsetof(EnterJITStack, token));
const Address slot_vp(sp, offsetof(EnterJITStack, vp));
static_assert(OsrFrameReg == r3);
Assembler* aasm = &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.startDataTransferM(IsStore, sp, DB, WriteBack);
masm.transferReg(r4); // [sp,0]
masm.transferReg(r5); // [sp,4]
masm.transferReg(r6); // [sp,8]
masm.transferReg(r7); // [sp,12]
masm.transferReg(r8); // [sp,16]
masm.transferReg(r9); // [sp,20]
masm.transferReg(r10); // [sp,24]
masm.transferReg(r11); // [sp,28]
// The abi does not expect r12 (ip) to be preserved
masm.transferReg(lr); // [sp,32]
// The 5th argument is located at [sp, 36]
masm.finishDataTransfer();
// Add padding word.
masm.subPtr(Imm32(sizeof(void*)), sp);
// Push the float registers.
masm.transferMultipleByRuns(NonVolatileFloatRegs, IsStore, sp, DB);
// Load calleeToken into r9.
masm.loadPtr(slot_token, r9);
// Save stack pointer.
masm.movePtr(sp, r11);
// Load the number of actual arguments into r10.
masm.loadPtr(slot_vp, r10);
masm.unboxInt32(Address(r10, 0), r10);
{
Label noNewTarget;
masm.branchTest32(Assembler::Zero, r9,
Imm32(CalleeToken_FunctionConstructing), &noNewTarget);
masm.add32(Imm32(1), r1);
masm.bind(&noNewTarget);
}
// Guarantee stack alignment of Jit frames.
//
// This code moves the stack pointer to the location where it should be when
// we enter the Jit frame. It moves the stack pointer such that we have
// enough space reserved for pushing the arguments, and the JitFrameLayout.
// The stack pointer is also aligned on the alignment expected by the Jit
// frames.
//
// At the end the register r4, is a pointer to the stack where the first
// argument is expected by the Jit frame.
//
aasm->as_sub(r4, sp, O2RegImmShift(r1, LSL, 3)); // r4 = sp - argc*8
aasm->as_bic(r4, r4, Imm8(JitStackAlignment - 1));
// r4 is now the aligned on the bottom of the list of arguments.
static_assert(
sizeof(JitFrameLayout) % JitStackAlignment == 0,
"No need to consider the JitFrameLayout for aligning the stack");
// sp' = ~(JitStackAlignment - 1) & (sp - argc * sizeof(Value))
masm.movePtr(r4, sp);
// Get a copy of the number of args to use as a decrement counter, also set
// the zero condition code.
aasm->as_mov(r5, O2Reg(r1), SetCC);
// 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.
aasm->as_b(&footer, Assembler::Zero);
// Get the top of the loop.
masm.bind(&header);
aasm->as_sub(r5, r5, Imm8(1), SetCC);
// We could be more awesome, and unroll this, using a loadm
// (particularly since the offset is effectively 0) but that seems more
// error prone, and complex.
// BIG FAT WARNING: this loads both r6 and r7.
aasm->as_extdtr(IsLoad, 64, true, PostIndex, r6,
EDtrAddr(r2, EDtrOffImm(8)));
aasm->as_extdtr(IsStore, 64, true, PostIndex, r6,
EDtrAddr(r4, EDtrOffImm(8)));
aasm->as_b(&header, Assembler::NonZero);
masm.bind(&footer);
}
// Push the callee token.
masm.push(r9);
// Push the frame descriptor.
masm.pushFrameDescriptorForJitCall(FrameType::CppToJSJit, r10, r10);
Label returnLabel;
{
// Handle Interpreter -> Baseline OSR.
AllocatableGeneralRegisterSet regs(GeneralRegisterSet::All());
MOZ_ASSERT(!regs.has(r11));
regs.take(OsrFrameReg);
regs.take(r0); // jitcode
MOZ_ASSERT(!regs.has(ReturnReg), "ReturnReg matches r0");
const Address slot_numStackValues(r11,
offsetof(EnterJITStack, numStackValues));
Label notOsr;
masm.branchTestPtr(Assembler::Zero, OsrFrameReg, OsrFrameReg, ¬Osr);
Register scratch = regs.takeAny();
Register numStackValues = regs.takeAny();
masm.load32(slot_numStackValues, numStackValues);
// Write return address. On ARM, CodeLabel is only used for tableswitch,
// so we can't use it here to get the return address. Instead, we use pc
// + a fixed offset to a jump to returnLabel. The pc register holds pc +
// 8, so we add the size of 2 instructions to skip the instructions
// emitted by push and jump(&skipJump).
{
AutoForbidPoolsAndNops afp(&masm, 5);
Label skipJump;
masm.mov(pc, scratch);
masm.addPtr(Imm32(2 * sizeof(uint32_t)), scratch);
masm.push(scratch);
masm.jump(&skipJump);
masm.jump(&returnLabel);
masm.bind(&skipJump);
}
// Frame prologue.
masm.push(FramePointer);
masm.mov(sp, FramePointer);
// Reserve frame.
masm.subPtr(Imm32(BaselineFrame::Size()), sp);
Register framePtrScratch = regs.takeAny();
masm.touchFrameValues(numStackValues, scratch, framePtrScratch);
masm.mov(sp, framePtrScratch);
// Reserve space for locals and stack values.
masm.ma_lsl(Imm32(3), numStackValues, scratch);
masm.ma_sub(sp, scratch, sp);
// Enter exit frame.
masm.pushFrameDescriptor(FrameType::BaselineJS);
masm.push(Imm32(0)); // Fake return address.
masm.push(FramePointer);
// No GC things to mark on the stack, push a bare token.
masm.loadJSContext(scratch);
masm.enterFakeExitFrame(scratch, scratch, ExitFrameType::Bare);
masm.push(r0); // jitcode
using Fn = bool (*)(BaselineFrame* frame, InterpreterFrame* interpFrame,
uint32_t numStackValues);
masm.setupUnalignedABICall(scratch);
masm.passABIArg(framePtrScratch); // BaselineFrame
masm.passABIArg(OsrFrameReg); // InterpreterFrame
masm.passABIArg(numStackValues);
masm.callWithABI<Fn, jit::InitBaselineFrameForOsr>(
ABIType::General, CheckUnsafeCallWithABI::DontCheckHasExitFrame);
Register jitcode = regs.takeAny();
masm.pop(jitcode);
MOZ_ASSERT(jitcode != ReturnReg);
Label error;
masm.addPtr(Imm32(ExitFrameLayout::SizeWithFooter()), sp);
masm.branchIfFalseBool(ReturnReg, &error);
// If OSR-ing, then emit instrumentation for setting lastProfilerFrame
// if profiler instrumentation is enabled.
{
Label skipProfilingInstrumentation;
AbsoluteAddress addressOfEnabled(
cx->runtime()->geckoProfiler().addressOfEnabled());
masm.branch32(Assembler::Equal, addressOfEnabled, Imm32(0),
&skipProfilingInstrumentation);
masm.profilerEnterFrame(FramePointer, scratch);
masm.bind(&skipProfilingInstrumentation);
}
masm.jump(jitcode);
// OOM: frame epilogue, load error value, discard return address and return.
masm.bind(&error);
masm.mov(FramePointer, sp);
masm.pop(FramePointer);
masm.addPtr(Imm32(sizeof(uintptr_t)), sp); // Return address.
masm.moveValue(MagicValue(JS_ION_ERROR), JSReturnOperand);
masm.jump(&returnLabel);
masm.bind(¬Osr);
// Load the scope chain in R1.
MOZ_ASSERT(R1.scratchReg() != r0);
masm.loadPtr(Address(r11, offsetof(EnterJITStack, scopeChain)),
R1.scratchReg());
}
// The callee will push the return address and frame pointer on the stack,
// thus we check that the stack would be aligned once the call is complete.
masm.assertStackAlignment(JitStackAlignment, 2 * sizeof(uintptr_t));
// Call the function.
masm.callJitNoProfiler(r0);
// Interpreter -> Baseline OSR will return here.
masm.bind(&returnLabel);
// Discard arguments and padding. Set sp to the address of the EnterJITStack
// on the stack.
masm.mov(r11, sp);
// Store the returned value into the slot_vp
masm.loadPtr(slot_vp, r5);
masm.storeValue(JSReturnOperand, Address(r5, 0));
// Restore non-volatile registers and return.
GenerateReturn(masm, true);
}
// static
mozilla::Maybe<::JS::ProfilingFrameIterator::RegisterState>
JitRuntime::getCppEntryRegisters(JitFrameLayout* frameStackAddress) {
// Not supported, or not implemented yet.
// TODO: Implement along with the corresponding stack-walker changes, in
return mozilla::Nothing{};
}
void JitRuntime::generateInvalidator(MacroAssembler& masm, Label* bailoutTail) {
// See large comment in x86's JitRuntime::generateInvalidator.
AutoCreatedBy acb(masm, "JitRuntime::generateInvalidator");
invalidatorOffset_ = startTrampolineCode(masm);
// At this point, one of two things has happened:
// 1) Execution has just returned from C code, which left the stack aligned
// 2) Execution has just returned from Ion code, which left the stack
// unaligned. The old return address should not matter, but we still want the
// stack to be aligned, and there is no good reason to automatically align it
// with a call to setupUnalignedABICall.
masm.as_bic(sp, sp, Imm8(7));
masm.startDataTransferM(IsStore, sp, DB, WriteBack);
// We don't have to push everything, but this is likely easier.
// Setting regs_.
for (uint32_t i = 0; i < Registers::Total; i++) {
masm.transferReg(Register::FromCode(i));
}
masm.finishDataTransfer();
// Since our datastructures for stack inspection are compile-time fixed,
// if there are only 16 double registers, then we need to reserve
// space on the stack for the missing 16.
if (FloatRegisters::ActualTotalPhys() != FloatRegisters::TotalPhys) {
ScratchRegisterScope scratch(masm);
int missingRegs =
FloatRegisters::TotalPhys - FloatRegisters::ActualTotalPhys();
masm.ma_sub(Imm32(missingRegs * sizeof(double)), sp, scratch);
}
masm.startFloatTransferM(IsStore, sp, DB, WriteBack);
for (uint32_t i = 0; i < FloatRegisters::ActualTotalPhys(); i++) {
masm.transferFloatReg(FloatRegister(i, FloatRegister::Double));
}
masm.finishFloatTransfer();
masm.ma_mov(sp, r0);
// Reserve 8 bytes for the outparam to ensure alignment for
// setupAlignedABICall.
masm.reserveStack(sizeof(void*) * 2);
masm.mov(sp, r1);
using Fn = bool (*)(InvalidationBailoutStack* sp, BaselineBailoutInfo** info);
masm.setupAlignedABICall();
masm.passABIArg(r0);
masm.passABIArg(r1);
masm.callWithABI<Fn, InvalidationBailout>(
ABIType::General, CheckUnsafeCallWithABI::DontCheckOther);
masm.pop(r2); // Get bailoutInfo outparam.
// Pop the machine state and the dead frame.
masm.moveToStackPtr(FramePointer);
// Jump to shared bailout tail. The BailoutInfo pointer has to be in r2.
masm.jump(bailoutTail);
}
void JitRuntime::generateArgumentsRectifier(MacroAssembler& masm,
ArgumentsRectifierKind kind) {
AutoCreatedBy acb(masm, "JitRuntime::generateArgumentsRectifier");
switch (kind) {
case ArgumentsRectifierKind::Normal:
argumentsRectifierOffset_ = startTrampolineCode(masm);
break;
case ArgumentsRectifierKind::TrialInlining:
trialInliningArgumentsRectifierOffset_ = startTrampolineCode(masm);
break;
}
masm.pushReturnAddress();
// Frame prologue.
//
// NOTE: if this changes, fix the Baseline bailout code too!
// See BaselineStackBuilder::calculatePrevFramePtr and
// BaselineStackBuilder::buildRectifierFrame (in BaselineBailouts.cpp).
masm.push(FramePointer);
masm.mov(StackPointer, FramePointer);
static_assert(JitStackAlignment == sizeof(Value));
// Copy number of actual arguments into r0 and r8.
masm.loadNumActualArgs(FramePointer, r0);
masm.mov(r0, r8);
// Load the number of |undefined|s to push into r6.
masm.loadPtr(
Address(FramePointer, RectifierFrameLayout::offsetOfCalleeToken()), r1);
{
ScratchRegisterScope scratch(masm);
masm.ma_and(Imm32(CalleeTokenMask), r1, r6, scratch);
}
masm.loadFunctionArgCount(r6, r6);
masm.ma_sub(r6, r8, r2);
// Get the topmost argument.
{
ScratchRegisterScope scratch(masm);
masm.ma_alu(sp, lsl(r8, 3), r3, OpAdd); // r3 <- sp + nargs * 8
masm.ma_add(r3, Imm32(sizeof(RectifierFrameLayout)), r3, scratch);
}
{
Label notConstructing;
masm.branchTest32(Assembler::Zero, r1,
Imm32(CalleeToken_FunctionConstructing),
¬Constructing);
// Add sizeof(Value) to overcome |this|
masm.as_extdtr(IsLoad, 64, true, Offset, r4, EDtrAddr(r3, EDtrOffImm(8)));
masm.as_extdtr(IsStore, 64, true, PreIndex, r4,
EDtrAddr(sp, EDtrOffImm(-8)));
masm.bind(¬Constructing);
}
// Push undefined.
masm.moveValue(UndefinedValue(), ValueOperand(r5, r4));
{
Label undefLoopTop;
masm.bind(&undefLoopTop);
masm.as_extdtr(IsStore, 64, true, PreIndex, r4,
EDtrAddr(sp, EDtrOffImm(-8)));
masm.as_sub(r2, r2, Imm8(1), SetCC);
masm.ma_b(&undefLoopTop, Assembler::NonZero);
}
// Push arguments, |nargs| + 1 times (to include |this|).
{
Label copyLoopTop;
masm.bind(©LoopTop);
masm.as_extdtr(IsLoad, 64, true, PostIndex, r4,
EDtrAddr(r3, EDtrOffImm(-8)));
masm.as_extdtr(IsStore, 64, true, PreIndex, r4,
EDtrAddr(sp, EDtrOffImm(-8)));
masm.as_sub(r8, r8, Imm8(1), SetCC);
masm.ma_b(©LoopTop, Assembler::NotSigned);
}
// Construct JitFrameLayout.
masm.ma_push(r1); // callee token
masm.pushFrameDescriptorForJitCall(FrameType::Rectifier, r0, r0);
// Call the target function.
masm.andPtr(Imm32(CalleeTokenMask), r1);
switch (kind) {
case ArgumentsRectifierKind::Normal:
masm.loadJitCodeRaw(r1, r3);
argumentsRectifierReturnOffset_ = masm.callJitNoProfiler(r3);
break;
case ArgumentsRectifierKind::TrialInlining:
Label noBaselineScript, done;
masm.loadBaselineJitCodeRaw(r1, r3, &noBaselineScript);
masm.callJitNoProfiler(r3);
masm.jump(&done);
// See BaselineCacheIRCompiler::emitCallInlinedFunction.
masm.bind(&noBaselineScript);
masm.loadJitCodeRaw(r1, r3);
masm.callJitNoProfiler(r3);
masm.bind(&done);
break;
}
masm.mov(FramePointer, StackPointer);
masm.pop(FramePointer);
masm.ret();
}
static void PushBailoutFrame(MacroAssembler& masm, Register spArg) {
#ifdef ENABLE_WASM_SIMD
# error "Needs more careful logic if SIMD is enabled"
#endif
// STEP 1a: Save our register sets to the stack so Bailout() can read
// everything.
// sp % 8 == 0
masm.startDataTransferM(IsStore, sp, DB, WriteBack);
// We don't have to push everything, but this is likely easier.
// Setting regs_.
for (uint32_t i = 0; i < Registers::Total; i++) {
masm.transferReg(Register::FromCode(i));
}
masm.finishDataTransfer();
ScratchRegisterScope scratch(masm);
// Since our datastructures for stack inspection are compile-time fixed,
// if there are only 16 double registers, then we need to reserve
// space on the stack for the missing 16.
if (FloatRegisters::ActualTotalPhys() != FloatRegisters::TotalPhys) {
int missingRegs =
FloatRegisters::TotalPhys - FloatRegisters::ActualTotalPhys();
masm.ma_sub(Imm32(missingRegs * sizeof(double)), sp, scratch);
}
masm.startFloatTransferM(IsStore, sp, DB, WriteBack);
for (uint32_t i = 0; i < FloatRegisters::ActualTotalPhys(); i++) {
masm.transferFloatReg(FloatRegister(i, FloatRegister::Double));
}
masm.finishFloatTransfer();
// The current stack pointer is the first argument to jit::Bailout.
masm.ma_mov(sp, spArg);
}
static void GenerateBailoutThunk(MacroAssembler& masm, Label* bailoutTail) {
PushBailoutFrame(masm, r0);
// Make space for Bailout's bailoutInfo outparam.
masm.reserveStack(sizeof(void*));
masm.mov(sp, r1);
using Fn = bool (*)(BailoutStack* sp, BaselineBailoutInfo** info);
masm.setupAlignedABICall();
masm.passABIArg(r0);
masm.passABIArg(r1);
masm.callWithABI<Fn, Bailout>(ABIType::General,
CheckUnsafeCallWithABI::DontCheckOther);
masm.pop(r2); // Get the bailoutInfo outparam.
// Remove both the bailout frame and the topmost Ion frame's stack.
masm.moveToStackPtr(FramePointer);
// Jump to shared bailout tail. The BailoutInfo pointer has to be in r2.
masm.jump(bailoutTail);
}
void JitRuntime::generateBailoutHandler(MacroAssembler& masm,
Label* bailoutTail) {
AutoCreatedBy acb(masm, "JitRuntime::generateBailoutHandler");
bailoutHandlerOffset_ = startTrampolineCode(masm);
GenerateBailoutThunk(masm, bailoutTail);
}
bool JitRuntime::generateVMWrapper(JSContext* cx, MacroAssembler& masm,
VMFunctionId id, const VMFunctionData& f,
DynFn nativeFun, uint32_t* wrapperOffset) {
AutoCreatedBy acb(masm, "JitRuntime::generateVMWrapper");
*wrapperOffset = startTrampolineCode(masm);
AllocatableGeneralRegisterSet regs(Register::Codes::WrapperMask);
static_assert(
(Register::Codes::VolatileMask & ~Register::Codes::WrapperMask) == 0,
"Wrapper register set must be a superset of Volatile register set.");
// The context is the first argument; r0 is the first argument register.
Register cxreg = r0;
regs.take(cxreg);
// On link-register platforms, it is the responsibility of the VM *callee* to
// push the return address, while the caller must ensure that the address
// is stored in lr on entry. This allows the VM wrapper to work with both
// direct calls and tail calls.
masm.pushReturnAddress();
// Push the frame pointer to finish the exit frame, then link it up.
masm.Push(FramePointer);
masm.moveStackPtrTo(FramePointer);
masm.loadJSContext(cxreg);
masm.enterExitFrame(cxreg, regs.getAny(), id);
// Reserve space for the outparameter.
masm.reserveVMFunctionOutParamSpace(f);
masm.setupUnalignedABICallDontSaveRestoreSP();
masm.passABIArg(cxreg);
size_t argDisp = ExitFrameLayout::Size();
// Copy any arguments.
for (uint32_t explicitArg = 0; explicitArg < f.explicitArgs; explicitArg++) {
switch (f.argProperties(explicitArg)) {
case VMFunctionData::WordByValue:
masm.passABIArg(MoveOperand(FramePointer, argDisp), ABIType::General);
argDisp += sizeof(void*);
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(FramePointer, argDisp), ABIType::Float64);
argDisp += sizeof(double);
break;
case VMFunctionData::WordByRef:
masm.passABIArg(MoveOperand(FramePointer, argDisp,
MoveOperand::Kind::EffectiveAddress),
ABIType::General);
argDisp += sizeof(void*);
break;
case VMFunctionData::DoubleByRef:
masm.passABIArg(MoveOperand(FramePointer, argDisp,
MoveOperand::Kind::EffectiveAddress),
ABIType::General);
argDisp += 2 * sizeof(void*);
break;
}
}
// Copy the implicit outparam, if any.
const int32_t outParamOffset =
-int32_t(ExitFooterFrame::Size()) - f.sizeOfOutParamStackSlot();
if (f.outParam != Type_Void) {
masm.passABIArg(MoveOperand(FramePointer, outParamOffset,
MoveOperand::Kind::EffectiveAddress),
ABIType::General);
}
masm.callWithABI(nativeFun, ABIType::General,
CheckUnsafeCallWithABI::DontCheckHasExitFrame);
// Test for failure.
switch (f.failType()) {
case Type_Cell:
masm.branchTestPtr(Assembler::Zero, r0, r0, masm.failureLabel());
break;
case Type_Bool:
masm.branchIfFalseBool(r0, masm.failureLabel());
break;
case Type_Void:
break;
default:
MOZ_CRASH("unknown failure kind");
}
// Load the outparam.
masm.loadVMFunctionOutParam(f, Address(FramePointer, outParamOffset));
// Until C++ code is instrumented against Spectre, prevent speculative
// execution from returning any private data.
if (f.returnsData() && JitOptions.spectreJitToCxxCalls) {
masm.speculationBarrier();
}
// Pop frame and restore frame pointer.
masm.moveToStackPtr(FramePointer);
masm.pop(FramePointer);
// Return. Subtract sizeof(void*) for the frame pointer.
masm.retn(Imm32(sizeof(ExitFrameLayout) - sizeof(void*) +
f.explicitStackSlots() * sizeof(void*) +
f.extraValuesToPop * sizeof(Value)));
return true;
}
uint32_t JitRuntime::generatePreBarrier(JSContext* cx, MacroAssembler& masm,
MIRType type) {
AutoCreatedBy acb(masm, "JitRuntime::generatePreBarrier");
uint32_t offset = startTrampolineCode(masm);
masm.pushReturnAddress();
static_assert(PreBarrierReg == r1);
Register temp1 = r2;
Register temp2 = r3;
Register temp3 = r4;
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;
save.set() =
RegisterSet(GeneralRegisterSet(Registers::VolatileMask),
FloatRegisterSet(FloatRegisters::VolatileDoubleMask));
masm.PushRegsInMask(save);
masm.movePtr(ImmPtr(cx->runtime()), r0);
masm.setupUnalignedABICall(r2);
masm.passABIArg(r0);
masm.passABIArg(r1);
masm.callWithABI(JitPreWriteBarrier(type));
masm.PopRegsInMask(save);
masm.ret();
masm.bind(&noBarrier);
masm.pop(temp3);
masm.pop(temp2);
masm.pop(temp1);
masm.ret();
return offset;
}
void JitRuntime::generateBailoutTailStub(MacroAssembler& masm,
Label* bailoutTail) {
AutoCreatedBy acb(masm, "JitRuntime::generateBailoutTailStub");
masm.bind(bailoutTail);
masm.generateBailoutTail(r1, r2);
}