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AssemblyHelpers.cpp
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2035 lines (1769 loc) · 85.3 KB
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/*
* Copyright (C) 2011-2023 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "AssemblyHelpers.h"
#if ENABLE(JIT)
#include "AccessCase.h"
#include "AssemblyHelpersSpoolers.h"
#include "JITOperations.h"
#include "JSArrayBufferView.h"
#include "JSCJSValueInlines.h"
#include "JSDataView.h"
#include "LinkBuffer.h"
#include "MaxFrameExtentForSlowPathCall.h"
#include "MegamorphicCache.h"
#include "SuperSampler.h"
#include "ThunkGenerators.h"
#include "UnlinkedCodeBlock.h"
#include <wtf/TZoneMallocInlines.h>
#if ENABLE(WEBASSEMBLY)
#include "WasmContext.h"
#include "WasmMemoryInformation.h"
#include "WasmInstance.h"
#endif
namespace JSC {
namespace AssemblyHelpersInternal {
constexpr bool dumpVerbose = false;
}
WTF_MAKE_TZONE_ALLOCATED_IMPL(AssemblyHelpers);
AssemblyHelpers::Jump AssemblyHelpers::branchIfFastTypedArray(GPRReg baseGPR)
{
return branch8(
Equal,
Address(baseGPR, JSArrayBufferView::offsetOfMode()),
TrustedImm32(FastTypedArray));
}
AssemblyHelpers::Jump AssemblyHelpers::branchIfNotFastTypedArray(GPRReg baseGPR)
{
return branch8(
NotEqual,
Address(baseGPR, JSArrayBufferView::offsetOfMode()),
TrustedImm32(FastTypedArray));
}
void AssemblyHelpers::incrementSuperSamplerCount()
{
add32(TrustedImm32(1), AbsoluteAddress(bitwise_cast<const void*>(&g_superSamplerCount)));
}
void AssemblyHelpers::decrementSuperSamplerCount()
{
sub32(TrustedImm32(1), AbsoluteAddress(bitwise_cast<const void*>(&g_superSamplerCount)));
}
void AssemblyHelpers::purifyNaN(FPRReg fpr)
{
MacroAssembler::Jump notNaN = branchIfNotNaN(fpr);
static const double NaN = PNaN;
loadDouble(TrustedImmPtr(&NaN), fpr);
notNaN.link(this);
}
#if ENABLE(SAMPLING_FLAGS)
void AssemblyHelpers::setSamplingFlag(int32_t flag)
{
ASSERT(flag >= 1);
ASSERT(flag <= 32);
or32(TrustedImm32(1u << (flag - 1)), AbsoluteAddress(SamplingFlags::addressOfFlags()));
}
void AssemblyHelpers::clearSamplingFlag(int32_t flag)
{
ASSERT(flag >= 1);
ASSERT(flag <= 32);
and32(TrustedImm32(~(1u << (flag - 1))), AbsoluteAddress(SamplingFlags::addressOfFlags()));
}
#endif
#if ASSERT_ENABLED
#if USE(JSVALUE64)
void AssemblyHelpers::jitAssertIsInt32(GPRReg gpr)
{
if (!Options::useJITAsserts())
return;
#if CPU(X86_64) || CPU(ARM64)
Jump checkInt32 = branch64(BelowOrEqual, gpr, TrustedImm64(static_cast<uintptr_t>(0xFFFFFFFFu)));
abortWithReason(AHIsNotInt32);
checkInt32.link(this);
#else
UNUSED_PARAM(gpr);
#endif
}
void AssemblyHelpers::jitAssertIsJSInt32(GPRReg gpr)
{
if (!Options::useJITAsserts())
return;
Jump checkJSInt32 = branch64(AboveOrEqual, gpr, GPRInfo::numberTagRegister);
abortWithReason(AHIsNotJSInt32);
checkJSInt32.link(this);
}
void AssemblyHelpers::jitAssertIsJSNumber(GPRReg gpr)
{
if (!Options::useJITAsserts())
return;
Jump checkJSNumber = branchTest64(MacroAssembler::NonZero, gpr, GPRInfo::numberTagRegister);
abortWithReason(AHIsNotJSNumber);
checkJSNumber.link(this);
}
void AssemblyHelpers::jitAssertIsJSDouble(GPRReg gpr)
{
if (!Options::useJITAsserts())
return;
Jump checkJSInt32 = branch64(AboveOrEqual, gpr, GPRInfo::numberTagRegister);
Jump checkJSNumber = branchTest64(MacroAssembler::NonZero, gpr, GPRInfo::numberTagRegister);
checkJSInt32.link(this);
abortWithReason(AHIsNotJSDouble);
checkJSNumber.link(this);
}
void AssemblyHelpers::jitAssertIsCell(GPRReg gpr)
{
if (!Options::useJITAsserts())
return;
Jump checkCell = branchTest64(MacroAssembler::Zero, gpr, GPRInfo::notCellMaskRegister);
abortWithReason(AHIsNotCell);
checkCell.link(this);
}
void AssemblyHelpers::jitAssertTagsInPlace()
{
if (!Options::useJITAsserts())
return;
Jump ok = branch64(Equal, GPRInfo::numberTagRegister, TrustedImm64(JSValue::NumberTag));
abortWithReason(AHNumberTagNotInPlace);
breakpoint();
ok.link(this);
ok = branch64(Equal, GPRInfo::notCellMaskRegister, TrustedImm64(JSValue::NotCellMask));
abortWithReason(AHNotCellMaskNotInPlace);
ok.link(this);
}
#elif USE(JSVALUE32_64)
void AssemblyHelpers::jitAssertIsInt32(GPRReg gpr)
{
if (!Options::useJITAsserts())
return;
UNUSED_PARAM(gpr);
}
void AssemblyHelpers::jitAssertIsJSInt32(GPRReg gpr)
{
if (!Options::useJITAsserts())
return;
Jump checkJSInt32 = branch32(Equal, gpr, TrustedImm32(JSValue::Int32Tag));
abortWithReason(AHIsNotJSInt32);
checkJSInt32.link(this);
}
void AssemblyHelpers::jitAssertIsJSNumber(GPRReg gpr)
{
if (!Options::useJITAsserts())
return;
Jump checkJSInt32 = branch32(Equal, gpr, TrustedImm32(JSValue::Int32Tag));
Jump checkJSDouble = branch32(Below, gpr, TrustedImm32(JSValue::LowestTag));
abortWithReason(AHIsNotJSNumber);
checkJSInt32.link(this);
checkJSDouble.link(this);
}
void AssemblyHelpers::jitAssertIsJSDouble(GPRReg gpr)
{
if (!Options::useJITAsserts())
return;
Jump checkJSDouble = branch32(Below, gpr, TrustedImm32(JSValue::LowestTag));
abortWithReason(AHIsNotJSDouble);
checkJSDouble.link(this);
}
void AssemblyHelpers::jitAssertIsCell(GPRReg gpr)
{
if (!Options::useJITAsserts())
return;
Jump checkCell = branchIfCell(gpr);
abortWithReason(AHIsNotCell);
checkCell.link(this);
}
void AssemblyHelpers::jitAssertTagsInPlace()
{
if (!Options::useJITAsserts())
return;
}
#endif // USE(JSVALUE32_64)
void AssemblyHelpers::jitAssertHasValidCallFrame()
{
if (!Options::useJITAsserts())
return;
Jump checkCFR = branchTestPtr(Zero, GPRInfo::callFrameRegister, TrustedImm32(7));
abortWithReason(AHCallFrameMisaligned);
checkCFR.link(this);
}
void AssemblyHelpers::jitAssertIsNull(GPRReg gpr)
{
if (!Options::useJITAsserts())
return;
Jump checkNull = branchTestPtr(Zero, gpr);
abortWithReason(AHIsNotNull);
checkNull.link(this);
}
void AssemblyHelpers::jitAssertArgumentCountSane()
{
if (!Options::useJITAsserts())
return;
Jump ok = branch32(Below, payloadFor(CallFrameSlot::argumentCountIncludingThis), TrustedImm32(10000000));
abortWithReason(AHInsaneArgumentCount);
ok.link(this);
}
void AssemblyHelpers::jitAssertCodeBlockOnCallFrameWithType(GPRReg scratchGPR, JITType type)
{
if (!Options::useJITAsserts())
return;
JIT_COMMENT(*this, "jitAssertCodeBlockOnCallFrameWithType | ", scratchGPR, " = callFrame->codeBlock->jitCode->jitType == ", type);
emitGetFromCallFrameHeaderPtr(CallFrameSlot::codeBlock, scratchGPR);
loadPtr(Address(scratchGPR, CodeBlock::jitCodeOffset()), scratchGPR);
load8(Address(scratchGPR, JITCode::offsetOfJITType()), scratchGPR);
Jump ok = branch32(Equal, scratchGPR, TrustedImm32(static_cast<unsigned>(type)));
abortWithReason(AHInvalidCodeBlock);
ok.link(this);
}
void AssemblyHelpers::jitAssertCodeBlockMatchesCurrentCalleeCodeBlockOnCallFrame(GPRReg scratchGPR, GPRReg scratchGPR2, UnlinkedCodeBlock& block)
{
if (!Options::useJITAsserts())
return;
if (block.codeType() != FunctionCode)
return;
auto kind = block.isConstructor() ? CodeForConstruct : CodeForCall;
JIT_COMMENT(*this, "jitAssertCodeBlockMatchesCurrentCalleeCodeBlockOnCallFrame with code block type: ", kind, " | ", scratchGPR, " = callFrame->callee->executableOrRareData");
emitGetFromCallFrameHeaderPtr(CallFrameSlot::callee, scratchGPR);
loadPtr(Address(scratchGPR, JSFunction::offsetOfExecutableOrRareData()), scratchGPR);
auto hasExecutable = branchTestPtr(Zero, scratchGPR, TrustedImm32(JSFunction::rareDataTag));
loadPtr(Address(scratchGPR, FunctionRareData::offsetOfExecutable() - JSFunction::rareDataTag), scratchGPR);
hasExecutable.link(this);
JIT_COMMENT(*this, scratchGPR, " = (", scratchGPR, ": Executable)->codeBlock");
loadPtr(Address(scratchGPR, FunctionExecutable::offsetOfCodeBlockFor(kind)), scratchGPR);
JIT_COMMENT(*this, scratchGPR2, " = callFrame->codeBlock");
emitGetFromCallFrameHeaderPtr(CallFrameSlot::codeBlock, scratchGPR2);
Jump ok = branch32(Equal, scratchGPR, scratchGPR2);
abortWithReason(AHInvalidCodeBlock);
ok.link(this);
}
void AssemblyHelpers::jitAssertCodeBlockOnCallFrameIsOptimizingJIT(GPRReg scratchGPR)
{
if (!Options::useJITAsserts())
return;
emitGetFromCallFrameHeaderPtr(CallFrameSlot::codeBlock, scratchGPR);
loadPtr(Address(scratchGPR, CodeBlock::jitCodeOffset()), scratchGPR);
load8(Address(scratchGPR, JITCode::offsetOfJITType()), scratchGPR);
JumpList ok;
ok.append(branch32(Equal, scratchGPR, TrustedImm32(static_cast<unsigned>(JITType::DFGJIT))));
ok.append(branch32(Equal, scratchGPR, TrustedImm32(static_cast<unsigned>(JITType::FTLJIT))));
abortWithReason(AHInvalidCodeBlock);
ok.link(this);
}
#endif // ASSERT_ENABLED
void AssemblyHelpers::jitReleaseAssertNoException(VM& vm)
{
Jump noException;
#if USE(JSVALUE64)
noException = branchTest64(Zero, AbsoluteAddress(vm.addressOfException()));
#elif USE(JSVALUE32_64)
noException = branch32(Equal, AbsoluteAddress(vm.addressOfException()), TrustedImm32(0));
#endif
abortWithReason(JITUncaughtExceptionAfterCall);
noException.link(this);
}
void AssemblyHelpers::callExceptionFuzz(VM& vm)
{
RELEASE_ASSERT(Options::useExceptionFuzz());
EncodedJSValue* buffer = vm.exceptionFuzzingBuffer(sizeof(EncodedJSValue) * (GPRInfo::numberOfRegisters + FPRInfo::numberOfRegisters));
for (unsigned i = 0; i < GPRInfo::numberOfRegisters; ++i) {
#if USE(JSVALUE64)
store64(GPRInfo::toRegister(i), buffer + i);
#else
store32(GPRInfo::toRegister(i), buffer + i);
#endif
}
for (unsigned i = 0; i < FPRInfo::numberOfRegisters; ++i) {
move(TrustedImmPtr(buffer + GPRInfo::numberOfRegisters + i), GPRInfo::regT0);
storeDouble(FPRInfo::toRegister(i), Address(GPRInfo::regT0));
}
// Set up one argument.
move(TrustedImmPtr(&vm), GPRInfo::argumentGPR0);
move(TrustedImmPtr(tagCFunction<OperationPtrTag>(operationExceptionFuzzWithCallFrame)), GPRInfo::nonPreservedNonReturnGPR);
prepareCallOperation(vm);
call(GPRInfo::nonPreservedNonReturnGPR, OperationPtrTag);
for (unsigned i = 0; i < FPRInfo::numberOfRegisters; ++i) {
move(TrustedImmPtr(buffer + GPRInfo::numberOfRegisters + i), GPRInfo::regT0);
loadDouble(Address(GPRInfo::regT0), FPRInfo::toRegister(i));
}
for (unsigned i = 0; i < GPRInfo::numberOfRegisters; ++i) {
#if USE(JSVALUE64)
load64(buffer + i, GPRInfo::toRegister(i));
#else
load32(buffer + i, GPRInfo::toRegister(i));
#endif
}
}
AssemblyHelpers::Jump AssemblyHelpers::emitJumpIfException(VM& vm)
{
return emitExceptionCheck(vm, NormalExceptionCheck);
}
AssemblyHelpers::Jump AssemblyHelpers::emitExceptionCheck(VM& vm, ExceptionCheckKind kind, ExceptionJumpWidth width, GPRReg exceptionReg)
{
if (UNLIKELY(Options::useExceptionFuzz()))
callExceptionFuzz(vm);
if (width == FarJumpWidth)
kind = (kind == NormalExceptionCheck ? InvertedExceptionCheck : NormalExceptionCheck);
Jump result;
if (exceptionReg != InvalidGPRReg) {
#if ASSERT_ENABLED
Jump ok = branchPtr(Equal, AbsoluteAddress(vm.addressOfException()), exceptionReg);
breakpoint();
ok.link(this);
#endif
result = branchTestPtr(kind == NormalExceptionCheck ? NonZero : Zero, exceptionReg);
} else
result = branchTestPtr(kind == NormalExceptionCheck ? NonZero : Zero, AbsoluteAddress(vm.addressOfException()));
if (width == NormalJumpWidth)
return result;
PatchableJump realJump = patchableJump();
result.link(this);
return realJump.m_jump;
}
AssemblyHelpers::Jump AssemblyHelpers::emitNonPatchableExceptionCheck(VM& vm, GPRReg exceptionReg)
{
return emitExceptionCheck(vm, NormalExceptionCheck, NormalJumpWidth, exceptionReg);
}
void AssemblyHelpers::emitStoreStructureWithTypeInfo(AssemblyHelpers& jit, TrustedImmPtr structure, RegisterID dest)
{
const Structure* structurePtr = reinterpret_cast<const Structure*>(structure.m_value);
#if USE(JSVALUE64)
jit.store64(TrustedImm64(static_cast<uint64_t>(structurePtr->id().bits()) | (static_cast<uint64_t>(structurePtr->typeInfoBlob()) << 32)), MacroAssembler::Address(dest, JSCell::structureIDOffset()));
if (ASSERT_ENABLED) {
Jump correctStructure = jit.branch32(Equal, MacroAssembler::Address(dest, JSCell::structureIDOffset()), TrustedImm32(structurePtr->id().bits()));
jit.abortWithReason(AHStructureIDIsValid);
correctStructure.link(&jit);
Jump correctIndexingType = jit.branch8(Equal, MacroAssembler::Address(dest, JSCell::indexingTypeAndMiscOffset()), TrustedImm32(structurePtr->indexingModeIncludingHistory()));
jit.abortWithReason(AHIndexingTypeIsValid);
correctIndexingType.link(&jit);
Jump correctType = jit.branch8(Equal, MacroAssembler::Address(dest, JSCell::typeInfoTypeOffset()), TrustedImm32(structurePtr->typeInfo().type()));
jit.abortWithReason(AHTypeInfoIsValid);
correctType.link(&jit);
Jump correctFlags = jit.branch8(Equal, MacroAssembler::Address(dest, JSCell::typeInfoFlagsOffset()), TrustedImm32(structurePtr->typeInfo().inlineTypeFlags()));
jit.abortWithReason(AHTypeInfoInlineTypeFlagsAreValid);
correctFlags.link(&jit);
}
#else
// Do a 32-bit wide store to initialize the cell's fields.
jit.store32(TrustedImm32(structurePtr->typeInfoBlob()), MacroAssembler::Address(dest, JSCell::indexingTypeAndMiscOffset()));
jit.storePtr(structure, MacroAssembler::Address(dest, JSCell::structureIDOffset()));
#endif
}
void AssemblyHelpers::loadProperty(GPRReg object, GPRReg offset, JSValueRegs result)
{
ASSERT(noOverlap(offset, result));
Jump isInline = branch32(LessThan, offset, TrustedImm32(firstOutOfLineOffset));
loadPtr(Address(object, JSObject::butterflyOffset()), result.payloadGPR());
neg32(offset);
signExtend32ToPtr(offset, offset);
Jump ready = jump();
isInline.link(this);
addPtr(
TrustedImm32(
static_cast<int32_t>(sizeof(JSObject)) -
(static_cast<int32_t>(firstOutOfLineOffset) - 2) * static_cast<int32_t>(sizeof(EncodedJSValue))),
object, result.payloadGPR());
ready.link(this);
loadValue(
BaseIndex(
result.payloadGPR(), offset, TimesEight, (firstOutOfLineOffset - 2) * sizeof(EncodedJSValue)),
result);
}
void AssemblyHelpers::storeProperty(JSValueRegs value, GPRReg object, GPRReg offset, GPRReg scratch)
{
// Actually, object can be the same to scratch.
ASSERT(noOverlap(offset, scratch));
ASSERT(noOverlap(value, scratch));
Jump isInline = branch32(LessThan, offset, TrustedImm32(firstOutOfLineOffset));
loadPtr(Address(object, JSObject::butterflyOffset()), scratch);
neg32(offset);
signExtend32ToPtr(offset, offset);
Jump ready = jump();
isInline.link(this);
addPtr(
TrustedImm32(
static_cast<int32_t>(sizeof(JSObject)) -
(static_cast<int32_t>(firstOutOfLineOffset) - 2) * static_cast<int32_t>(sizeof(EncodedJSValue))),
object, scratch);
ready.link(this);
storeValue(value, BaseIndex(scratch, offset, TimesEight, (firstOutOfLineOffset - 2) * sizeof(EncodedJSValue)));
}
#if USE(JSVALUE64)
AssemblyHelpers::JumpList AssemblyHelpers::loadMegamorphicProperty(VM& vm, GPRReg baseGPR, GPRReg uidGPR, UniquedStringImpl* uid, GPRReg resultGPR, GPRReg scratch1GPR, GPRReg scratch2GPR, GPRReg scratch3GPR)
{
// uidGPR can be InvalidGPRReg if uid is non-nullptr.
if (!uid)
ASSERT(uidGPR != InvalidGPRReg);
JumpList primaryFail;
JumpList slowCases;
load32(Address(baseGPR, JSCell::structureIDOffset()), scratch1GPR);
#if CPU(ARM64)
extractUnsignedBitfield32(scratch1GPR, TrustedImm32(MegamorphicCache::structureIDHashShift1), TrustedImm32(32 - MegamorphicCache::structureIDHashShift1), scratch2GPR);
xorUnsignedRightShift32(scratch2GPR, scratch1GPR, TrustedImm32(MegamorphicCache::structureIDHashShift2), scratch3GPR);
#else
urshift32(scratch1GPR, TrustedImm32(MegamorphicCache::structureIDHashShift1), scratch2GPR);
urshift32(scratch1GPR, TrustedImm32(MegamorphicCache::structureIDHashShift2), scratch3GPR);
xor32(scratch2GPR, scratch3GPR);
#endif
if (uid)
add32(TrustedImm32(uid->hash()), scratch3GPR);
else {
// Note that we don't test if the hash is zero here. AtomStringImpl's can't have a zero
// hash, however, a SymbolImpl may. But, because this is a cache, we don't care. We only
// ever load the result from the cache if the cache entry matches what we are querying for.
// So we either get super lucky and use zero for the hash and somehow collide with the entity
// we're looking for, or we realize we're comparing against another entity, and go to the
// slow path anyways.
load32(Address(uidGPR, UniquedStringImpl::flagsOffset()), scratch2GPR);
urshift32(TrustedImm32(StringImpl::s_flagCount), scratch2GPR);
add32(scratch2GPR, scratch3GPR);
}
and32(TrustedImm32(MegamorphicCache::loadCachePrimaryMask), scratch3GPR);
if (hasOneBitSet(sizeof(MegamorphicCache::LoadEntry))) // is a power of 2
lshift32(TrustedImm32(getLSBSet(sizeof(MegamorphicCache::LoadEntry))), scratch3GPR);
else
mul32(TrustedImm32(sizeof(MegamorphicCache::LoadEntry)), scratch3GPR, scratch3GPR);
auto& cache = vm.ensureMegamorphicCache();
move(TrustedImmPtr(&cache), scratch2GPR);
ASSERT(!MegamorphicCache::offsetOfLoadCachePrimaryEntries());
addPtr(scratch2GPR, scratch3GPR);
load16(Address(scratch2GPR, MegamorphicCache::offsetOfEpoch()), scratch2GPR);
primaryFail.append(branch32(NotEqual, scratch1GPR, Address(scratch3GPR, MegamorphicCache::LoadEntry::offsetOfStructureID())));
if (uid)
primaryFail.append(branchPtr(NotEqual, Address(scratch3GPR, MegamorphicCache::LoadEntry::offsetOfUid()), TrustedImmPtr(uid)));
else
primaryFail.append(branchPtr(NotEqual, Address(scratch3GPR, MegamorphicCache::LoadEntry::offsetOfUid()), uidGPR));
// We already hit StructureID and uid. And we get stale epoch for this entry.
// Since all entries in the secondary cache has stale epoch for this StructureID and uid pair, we should just go to the slow case.
slowCases.append(branch32WithMemory16(NotEqual, Address(scratch3GPR, MegamorphicCache::LoadEntry::offsetOfEpoch()), scratch2GPR));
// Cache hit!
Label cacheHit = label();
loadPtr(Address(scratch3GPR, MegamorphicCache::LoadEntry::offsetOfHolder()), scratch2GPR);
auto missed = branchTestPtr(Zero, scratch2GPR);
moveConditionally64(Equal, scratch2GPR, TrustedImm32(bitwise_cast<uintptr_t>(JSCell::seenMultipleCalleeObjects())), baseGPR, scratch2GPR, scratch1GPR);
load16(Address(scratch3GPR, MegamorphicCache::LoadEntry::offsetOfOffset()), scratch2GPR);
loadProperty(scratch1GPR, scratch2GPR, JSValueRegs { resultGPR });
auto done = jump();
// Secondary cache lookup. Now,
// 1. scratch1GPR holds StructureID.
// 2. scratch2GPR holds global epoch.
primaryFail.link(this);
if (uid)
add32(TrustedImm32(static_cast<uint32_t>(bitwise_cast<uintptr_t>(uid))), scratch1GPR, scratch3GPR);
else
add32(uidGPR, scratch1GPR, scratch3GPR);
addUnsignedRightShift32(scratch3GPR, scratch3GPR, TrustedImm32(MegamorphicCache::structureIDHashShift3), scratch3GPR);
and32(TrustedImm32(MegamorphicCache::loadCacheSecondaryMask), scratch3GPR);
if constexpr (hasOneBitSet(sizeof(MegamorphicCache::LoadEntry))) // is a power of 2
lshift32(TrustedImm32(getLSBSet(sizeof(MegamorphicCache::LoadEntry))), scratch3GPR);
else
mul32(TrustedImm32(sizeof(MegamorphicCache::LoadEntry)), scratch3GPR, scratch3GPR);
addPtr(TrustedImmPtr(bitwise_cast<uint8_t*>(&cache) + MegamorphicCache::offsetOfLoadCacheSecondaryEntries()), scratch3GPR);
slowCases.append(branch32(NotEqual, scratch1GPR, Address(scratch3GPR, MegamorphicCache::LoadEntry::offsetOfStructureID())));
if (uid)
slowCases.append(branchPtr(NotEqual, Address(scratch3GPR, MegamorphicCache::LoadEntry::offsetOfUid()), TrustedImmPtr(uid)));
else
slowCases.append(branchPtr(NotEqual, Address(scratch3GPR, MegamorphicCache::LoadEntry::offsetOfUid()), uidGPR));
slowCases.append(branch32WithMemory16(NotEqual, Address(scratch3GPR, MegamorphicCache::LoadEntry::offsetOfEpoch()), scratch2GPR));
jump().linkTo(cacheHit, this);
missed.link(this);
moveTrustedValue(jsUndefined(), JSValueRegs { resultGPR });
done.link(this);
return slowCases;
}
std::tuple<AssemblyHelpers::JumpList, AssemblyHelpers::JumpList> AssemblyHelpers::storeMegamorphicProperty(VM& vm, GPRReg baseGPR, GPRReg uidGPR, UniquedStringImpl* uid, GPRReg valueGPR, GPRReg scratch1GPR, GPRReg scratch2GPR, GPRReg scratch3GPR)
{
// uidGPR can be InvalidGPRReg if uid is non-nullptr.
if (!uid)
ASSERT(uidGPR != InvalidGPRReg);
JumpList primaryFail;
JumpList slowCases;
JumpList reallocatingCases;
load32(Address(baseGPR, JSCell::structureIDOffset()), scratch1GPR);
#if CPU(ARM64)
extractUnsignedBitfield32(scratch1GPR, TrustedImm32(MegamorphicCache::structureIDHashShift1), TrustedImm32(32 - MegamorphicCache::structureIDHashShift1), scratch2GPR);
xorUnsignedRightShift32(scratch2GPR, scratch1GPR, TrustedImm32(MegamorphicCache::structureIDHashShift4), scratch3GPR);
#else
urshift32(scratch1GPR, TrustedImm32(MegamorphicCache::structureIDHashShift1), scratch2GPR);
urshift32(scratch1GPR, TrustedImm32(MegamorphicCache::structureIDHashShift4), scratch3GPR);
xor32(scratch2GPR, scratch3GPR);
#endif
if (uid)
add32(TrustedImm32(uid->hash()), scratch3GPR);
else {
// Note that we don't test if the hash is zero here. AtomStringImpl's can't have a zero
// hash, however, a SymbolImpl may. But, because this is a cache, we don't care. We only
// ever load the result from the cache if the cache entry matches what we are querying for.
// So we either get super lucky and use zero for the hash and somehow collide with the entity
// we're looking for, or we realize we're comparing against another entity, and go to the
// slow path anyways.
load32(Address(uidGPR, UniquedStringImpl::flagsOffset()), scratch2GPR);
urshift32(TrustedImm32(StringImpl::s_flagCount), scratch2GPR);
add32(scratch2GPR, scratch3GPR);
}
and32(TrustedImm32(MegamorphicCache::storeCachePrimaryMask), scratch3GPR);
if (hasOneBitSet(sizeof(MegamorphicCache::StoreEntry))) // is a power of 2
lshift32(TrustedImm32(getLSBSet(sizeof(MegamorphicCache::StoreEntry))), scratch3GPR);
else
mul32(TrustedImm32(sizeof(MegamorphicCache::StoreEntry)), scratch3GPR, scratch3GPR);
auto& cache = vm.ensureMegamorphicCache();
move(TrustedImmPtr(&cache), scratch2GPR);
addPtr(scratch2GPR, scratch3GPR);
addPtr(TrustedImmPtr(MegamorphicCache::offsetOfStoreCachePrimaryEntries()), scratch3GPR);
load16(Address(scratch2GPR, MegamorphicCache::offsetOfEpoch()), scratch2GPR);
primaryFail.append(branch32(NotEqual, scratch1GPR, Address(scratch3GPR, MegamorphicCache::StoreEntry::offsetOfOldStructureID())));
if (uid)
primaryFail.append(branchPtr(NotEqual, Address(scratch3GPR, MegamorphicCache::StoreEntry::offsetOfUid()), TrustedImmPtr(uid)));
else
primaryFail.append(branchPtr(NotEqual, Address(scratch3GPR, MegamorphicCache::StoreEntry::offsetOfUid()), uidGPR));
// We already hit StructureID and uid. And we get stale epoch for this entry.
// Since all entries in the secondary cache has stale epoch for this StructureID and uid pair, we should just go to the slow case.
slowCases.append(branch32WithMemory16(NotEqual, Address(scratch3GPR, MegamorphicCache::StoreEntry::offsetOfEpoch()), scratch2GPR));
// Cache hit!
Label cacheHit = label();
reallocatingCases.append(branchTest8(NonZero, Address(scratch3GPR, MegamorphicCache::StoreEntry::offsetOfReallocating())));
load32(Address(scratch3GPR, MegamorphicCache::StoreEntry::offsetOfNewStructureID()), scratch2GPR);
load16(Address(scratch3GPR, MegamorphicCache::StoreEntry::offsetOfOffset()), scratch3GPR);
auto replaceCase = branch32(Equal, scratch2GPR, scratch1GPR);
// We only support non-allocating transition. This means we do not need to nuke Structure* for transition here.
store32(scratch2GPR, Address(baseGPR, JSCell::structureIDOffset()));
replaceCase.link(this);
storeProperty(JSValueRegs { valueGPR }, baseGPR, scratch3GPR, scratch1GPR);
auto done = jump();
// Secondary cache lookup
primaryFail.link(this);
if (uid)
add32(TrustedImm32(static_cast<uint32_t>(bitwise_cast<uintptr_t>(uid))), scratch1GPR, scratch3GPR);
else
add32(uidGPR, scratch1GPR, scratch3GPR);
addUnsignedRightShift32(scratch3GPR, scratch3GPR, TrustedImm32(MegamorphicCache::structureIDHashShift5), scratch3GPR);
and32(TrustedImm32(MegamorphicCache::storeCacheSecondaryMask), scratch3GPR);
if constexpr (hasOneBitSet(sizeof(MegamorphicCache::StoreEntry))) // is a power of 2
lshift32(TrustedImm32(getLSBSet(sizeof(MegamorphicCache::StoreEntry))), scratch3GPR);
else
mul32(TrustedImm32(sizeof(MegamorphicCache::StoreEntry)), scratch3GPR, scratch3GPR);
addPtr(TrustedImmPtr(bitwise_cast<uint8_t*>(&cache) + MegamorphicCache::offsetOfStoreCacheSecondaryEntries()), scratch3GPR);
slowCases.append(branch32(NotEqual, scratch1GPR, Address(scratch3GPR, MegamorphicCache::StoreEntry::offsetOfOldStructureID())));
if (uid)
slowCases.append(branchPtr(NotEqual, Address(scratch3GPR, MegamorphicCache::StoreEntry::offsetOfUid()), TrustedImmPtr(uid)));
else
slowCases.append(branchPtr(NotEqual, Address(scratch3GPR, MegamorphicCache::StoreEntry::offsetOfUid()), uidGPR));
slowCases.append(branch32WithMemory16(NotEqual, Address(scratch3GPR, MegamorphicCache::StoreEntry::offsetOfEpoch()), scratch2GPR));
jump().linkTo(cacheHit, this);
done.link(this);
return std::tuple { slowCases, reallocatingCases };
}
AssemblyHelpers::JumpList AssemblyHelpers::hasMegamorphicProperty(VM& vm, GPRReg baseGPR, GPRReg uidGPR, UniquedStringImpl* uid, GPRReg resultGPR, GPRReg scratch1GPR, GPRReg scratch2GPR, GPRReg scratch3GPR)
{
// uidGPR can be InvalidGPRReg if uid is non-nullptr.
if (!uid)
ASSERT(uidGPR != InvalidGPRReg);
JumpList primaryFail;
JumpList slowCases;
load32(Address(baseGPR, JSCell::structureIDOffset()), scratch1GPR);
#if CPU(ARM64)
extractUnsignedBitfield32(scratch1GPR, TrustedImm32(MegamorphicCache::structureIDHashShift1), TrustedImm32(32 - MegamorphicCache::structureIDHashShift1), scratch2GPR);
xorUnsignedRightShift32(scratch2GPR, scratch1GPR, TrustedImm32(MegamorphicCache::structureIDHashShift6), scratch3GPR);
#else
urshift32(scratch1GPR, TrustedImm32(MegamorphicCache::structureIDHashShift1), scratch2GPR);
urshift32(scratch1GPR, TrustedImm32(MegamorphicCache::structureIDHashShift6), scratch3GPR);
xor32(scratch2GPR, scratch3GPR);
#endif
if (uid)
add32(TrustedImm32(uid->hash()), scratch3GPR);
else {
// Note that we don't test if the hash is zero here. AtomStringImpl's can't have a zero
// hash, however, a SymbolImpl may. But, because this is a cache, we don't care. We only
// ever load the result from the cache if the cache entry matches what we are querying for.
// So we either get super lucky and use zero for the hash and somehow collide with the entity
// we're looking for, or we realize we're comparing against another entity, and go to the
// slow path anyways.
load32(Address(uidGPR, UniquedStringImpl::flagsOffset()), scratch2GPR);
urshift32(TrustedImm32(StringImpl::s_flagCount), scratch2GPR);
add32(scratch2GPR, scratch3GPR);
}
and32(TrustedImm32(MegamorphicCache::hasCachePrimaryMask), scratch3GPR);
if (hasOneBitSet(sizeof(MegamorphicCache::HasEntry))) // is a power of 2
lshift32(TrustedImm32(getLSBSet(sizeof(MegamorphicCache::HasEntry))), scratch3GPR);
else
mul32(TrustedImm32(sizeof(MegamorphicCache::HasEntry)), scratch3GPR, scratch3GPR);
auto& cache = vm.ensureMegamorphicCache();
move(TrustedImmPtr(&cache), scratch2GPR);
addPtr(scratch2GPR, scratch3GPR);
addPtr(TrustedImmPtr(MegamorphicCache::offsetOfHasCachePrimaryEntries()), scratch3GPR);
load16(Address(scratch2GPR, MegamorphicCache::offsetOfEpoch()), scratch2GPR);
primaryFail.append(branch32(NotEqual, scratch1GPR, Address(scratch3GPR, MegamorphicCache::HasEntry::offsetOfStructureID())));
if (uid)
primaryFail.append(branchPtr(NotEqual, Address(scratch3GPR, MegamorphicCache::HasEntry::offsetOfUid()), TrustedImmPtr(uid)));
else
primaryFail.append(branchPtr(NotEqual, Address(scratch3GPR, MegamorphicCache::HasEntry::offsetOfUid()), uidGPR));
// We already hit StructureID and uid. And we get stale epoch for this entry.
// Since all entries in the secondary cache has stale epoch for this StructureID and uid pair, we should just go to the slow case.
slowCases.append(branch32WithMemory16(NotEqual, Address(scratch3GPR, MegamorphicCache::HasEntry::offsetOfEpoch()), scratch2GPR));
// Cache hit!
Label cacheHit = label();
load16(Address(scratch3GPR, MegamorphicCache::HasEntry::offsetOfResult()), scratch2GPR);
boxBoolean(scratch2GPR, JSValueRegs { resultGPR });
auto done = jump();
// Secondary cache lookup. Now,
// 1. scratch1GPR holds StructureID.
// 2. scratch2GPR holds global epoch.
primaryFail.link(this);
if (uid)
add32(TrustedImm32(static_cast<uint32_t>(bitwise_cast<uintptr_t>(uid))), scratch1GPR, scratch3GPR);
else
add32(uidGPR, scratch1GPR, scratch3GPR);
addUnsignedRightShift32(scratch3GPR, scratch3GPR, TrustedImm32(MegamorphicCache::structureIDHashShift7), scratch3GPR);
and32(TrustedImm32(MegamorphicCache::hasCacheSecondaryMask), scratch3GPR);
if constexpr (hasOneBitSet(sizeof(MegamorphicCache::HasEntry))) // is a power of 2
lshift32(TrustedImm32(getLSBSet(sizeof(MegamorphicCache::HasEntry))), scratch3GPR);
else
mul32(TrustedImm32(sizeof(MegamorphicCache::HasEntry)), scratch3GPR, scratch3GPR);
addPtr(TrustedImmPtr(bitwise_cast<uint8_t*>(&cache) + MegamorphicCache::offsetOfHasCacheSecondaryEntries()), scratch3GPR);
slowCases.append(branch32(NotEqual, scratch1GPR, Address(scratch3GPR, MegamorphicCache::HasEntry::offsetOfStructureID())));
if (uid)
slowCases.append(branchPtr(NotEqual, Address(scratch3GPR, MegamorphicCache::HasEntry::offsetOfUid()), TrustedImmPtr(uid)));
else
slowCases.append(branchPtr(NotEqual, Address(scratch3GPR, MegamorphicCache::HasEntry::offsetOfUid()), uidGPR));
slowCases.append(branch32WithMemory16(NotEqual, Address(scratch3GPR, MegamorphicCache::HasEntry::offsetOfEpoch()), scratch2GPR));
jump().linkTo(cacheHit, this);
done.link(this);
return slowCases;
}
#endif
void AssemblyHelpers::emitNonNullDecodeZeroExtendedStructureID(RegisterID source, RegisterID dest)
{
#if ENABLE(STRUCTURE_ID_WITH_SHIFT)
lshift64(source, TrustedImm32(StructureID::encodeShiftAmount), dest);
#elif CPU(ADDRESS64)
// This could use BFI on arm64 but that only helps if the start of structure heap is encodable as a mov and not as an immediate in the add so it's probably not super important.
if constexpr (structureHeapAddressSize >= 4 * GB) {
ASSERT(structureHeapAddressSize == 4 * GB);
move(source, dest);
} else
and32(TrustedImm32(StructureID::structureIDMask), source, dest);
or64(TrustedImm64(startOfStructureHeap()), dest);
#else // not CPU(ADDRESS64)
move(source, dest);
#endif
}
void AssemblyHelpers::emitLoadStructure(VM&, RegisterID source, RegisterID dest)
{
load32(MacroAssembler::Address(source, JSCell::structureIDOffset()), dest);
emitNonNullDecodeZeroExtendedStructureID(dest, dest);
}
void AssemblyHelpers::emitEncodeStructureID(RegisterID source, RegisterID dest)
{
#if ENABLE(STRUCTURE_ID_WITH_SHIFT)
urshift64(source, TrustedImm32(StructureID::encodeShiftAmount), dest);
#elif CPU(ADDRESS64)
move(source, dest);
static_assert(StructureID::structureIDMask <= UINT32_MAX);
and64(TrustedImm32(static_cast<uint32_t>(StructureID::structureIDMask)), dest);
#else
move(source, dest);
#endif
}
void AssemblyHelpers::emitLoadPrototype(VM& vm, GPRReg objectGPR, JSValueRegs resultRegs, JumpList& slowPath)
{
ASSERT(resultRegs.payloadGPR() != objectGPR);
emitLoadStructure(vm, objectGPR, resultRegs.payloadGPR());
auto overridesGetPrototype = branchTest32(MacroAssembler::NonZero, MacroAssembler::Address(resultRegs.payloadGPR(), Structure::outOfLineTypeFlagsOffset()), TrustedImm32(OverridesGetPrototypeOutOfLine));
slowPath.append(overridesGetPrototype);
loadValue(MacroAssembler::Address(resultRegs.payloadGPR(), Structure::prototypeOffset()), resultRegs);
auto hasMonoProto = branchIfNotEmpty(resultRegs);
loadValue(MacroAssembler::Address(objectGPR, offsetRelativeToBase(knownPolyProtoOffset)), resultRegs);
hasMonoProto.link(this);
}
void AssemblyHelpers::makeSpaceOnStackForCCall()
{
unsigned stackOffset = WTF::roundUpToMultipleOf(stackAlignmentBytes(), maxFrameExtentForSlowPathCall);
if (stackOffset)
subPtr(TrustedImm32(stackOffset), stackPointerRegister);
}
void AssemblyHelpers::reclaimSpaceOnStackForCCall()
{
unsigned stackOffset = WTF::roundUpToMultipleOf(stackAlignmentBytes(), maxFrameExtentForSlowPathCall);
if (stackOffset)
addPtr(TrustedImm32(stackOffset), stackPointerRegister);
}
#if USE(JSVALUE64)
template<typename LoadFromHigh, typename StoreToHigh, typename LoadFromLow, typename StoreToLow>
void emitRandomThunkImpl(AssemblyHelpers& jit, GPRReg scratch0, GPRReg scratch1, GPRReg scratch2, FPRReg result, const LoadFromHigh& loadFromHigh, const StoreToHigh& storeToHigh, const LoadFromLow& loadFromLow, const StoreToLow& storeToLow)
{
// Inlined WeakRandom::advance().
// uint64_t x = m_low;
loadFromLow(scratch0);
// uint64_t y = m_high;
loadFromHigh(scratch1);
// m_low = y;
storeToLow(scratch1);
// x ^= x << 23;
jit.move(scratch0, scratch2);
jit.lshift64(AssemblyHelpers::TrustedImm32(23), scratch2);
jit.xor64(scratch2, scratch0);
// x ^= x >> 17;
jit.move(scratch0, scratch2);
jit.rshift64(AssemblyHelpers::TrustedImm32(17), scratch2);
jit.xor64(scratch2, scratch0);
// x ^= y ^ (y >> 26);
jit.move(scratch1, scratch2);
jit.rshift64(AssemblyHelpers::TrustedImm32(26), scratch2);
jit.xor64(scratch1, scratch2);
jit.xor64(scratch2, scratch0);
// m_high = x;
storeToHigh(scratch0);
// return x + y;
jit.add64(scratch1, scratch0);
// Extract random 53bit. [0, 53] bit is safe integer number ranges in double representation.
jit.move(AssemblyHelpers::TrustedImm64((1ULL << 53) - 1), scratch1);
jit.and64(scratch1, scratch0);
// Now, scratch0 is always in range of int64_t. Safe to convert it to double with cvtsi2sdq.
jit.convertInt64ToDouble(scratch0, result);
// Convert `(53bit double integer value) / (1 << 53)` to `(53bit double integer value) * (1.0 / (1 << 53))`.
// In latter case, `1.0 / (1 << 53)` will become a double value represented as (mantissa = 0 & exp = 970, it means 1e-(2**54)).
static constexpr double scale = 1.0 / (1ULL << 53);
// Multiplying 1e-(2**54) with the double integer does not change anything of the mantissa part of the double integer.
// It just reduces the exp part of the given 53bit double integer.
// (Except for 0.0. This is specially handled and in this case, exp just becomes 0.)
// Now we get 53bit precision random double value in [0, 1).
jit.move(AssemblyHelpers::TrustedImmPtr(&scale), scratch1);
jit.mulDouble(AssemblyHelpers::Address(scratch1), result);
}
void AssemblyHelpers::emitRandomThunk(JSGlobalObject* globalObject, GPRReg scratch0, GPRReg scratch1, GPRReg scratch2, FPRReg result)
{
void* lowAddress = reinterpret_cast<uint8_t*>(globalObject) + JSGlobalObject::weakRandomOffset() + WeakRandom::lowOffset();
void* highAddress = reinterpret_cast<uint8_t*>(globalObject) + JSGlobalObject::weakRandomOffset() + WeakRandom::highOffset();
auto loadFromHigh = [&](GPRReg high) {
load64(highAddress, high);
};
auto storeToHigh = [&](GPRReg high) {
store64(high, highAddress);
};
auto loadFromLow = [&](GPRReg low) {
load64(lowAddress, low);
};
auto storeToLow = [&](GPRReg low) {
store64(low, lowAddress);
};
emitRandomThunkImpl(*this, scratch0, scratch1, scratch2, result, loadFromHigh, storeToHigh, loadFromLow, storeToLow);
}
void AssemblyHelpers::emitRandomThunk(VM& vm, GPRReg scratch0, GPRReg scratch1, GPRReg scratch2, GPRReg scratch3, FPRReg result)
{
emitGetFromCallFrameHeaderPtr(CallFrameSlot::callee, scratch3);
emitLoadStructure(vm, scratch3, scratch3);
loadPtr(Address(scratch3, Structure::globalObjectOffset()), scratch3);
// Now, scratch3 holds JSGlobalObject*.
auto loadFromHigh = [&](GPRReg high) {
load64(Address(scratch3, JSGlobalObject::weakRandomOffset() + WeakRandom::highOffset()), high);
};
auto storeToHigh = [&](GPRReg high) {
store64(high, Address(scratch3, JSGlobalObject::weakRandomOffset() + WeakRandom::highOffset()));
};
auto loadFromLow = [&](GPRReg low) {
load64(Address(scratch3, JSGlobalObject::weakRandomOffset() + WeakRandom::lowOffset()), low);
};
auto storeToLow = [&](GPRReg low) {
store64(low, Address(scratch3, JSGlobalObject::weakRandomOffset() + WeakRandom::lowOffset()));
};
emitRandomThunkImpl(*this, scratch0, scratch1, scratch2, result, loadFromHigh, storeToHigh, loadFromLow, storeToLow);
}
#endif
void AssemblyHelpers::emitAllocateWithNonNullAllocator(GPRReg resultGPR, const JITAllocator& allocator, GPRReg allocatorGPR, GPRReg scratchGPR, JumpList& slowPath, SlowAllocationResult slowAllocationResult)
{
if (Options::forceGCSlowPaths()) {
slowPath.append(jump());
return;
}
// NOTE, some invariants of this function:
// - When going to the slow path, we must leave resultGPR with zero in it.
// - We *can not* use RegisterSetBuilder::macroScratchRegisters on x86.
// - We *can* use RegisterSetBuilder::macroScratchRegisters on ARM.
Jump popPath;
Jump zeroPath;
Jump done;
if (allocator.isConstant())
move(TrustedImmPtr(allocator.allocator().localAllocator()), allocatorGPR);
#if CPU(ARM) || CPU(ARM64)
auto dataTempRegister = getCachedDataTempRegisterIDAndInvalidate();
#endif
#if CPU(ARM64)
// On ARM64, we can leverage instructions like load-pair and shifted-add to make loading from the free list
// and extracting interval information use less instructions.
// Assert that we can use loadPairPtr for the interval bounds and nextInterval/secret.
ASSERT(FreeList::offsetOfIntervalEnd() - FreeList::offsetOfIntervalStart() == sizeof(uintptr_t));
ASSERT(FreeList::offsetOfNextInterval() - FreeList::offsetOfIntervalEnd() == sizeof(uintptr_t));
ASSERT(FreeList::offsetOfSecret() - FreeList::offsetOfNextInterval() == sizeof(uintptr_t));
// Bump allocation (fast path)
loadPairPtr(allocatorGPR, TrustedImm32(LocalAllocator::offsetOfFreeList() + FreeList::offsetOfIntervalStart()), resultGPR, scratchGPR);
popPath = branchPtr(RelationalCondition::AboveOrEqual, resultGPR, scratchGPR);
auto bumpLabel = label();
if (allocator.isConstant())
addPtr(TrustedImm32(allocator.allocator().cellSize()), resultGPR, scratchGPR);
else {
load32(Address(allocatorGPR, LocalAllocator::offsetOfCellSize()), scratchGPR);
addPtr(resultGPR, scratchGPR);
}
storePtr(scratchGPR, Address(allocatorGPR, LocalAllocator::offsetOfFreeList() + FreeList::offsetOfIntervalStart()));
done = jump();
// Get next interval (slower path)
popPath.link(this);
loadPairPtr(allocatorGPR, TrustedImm32(LocalAllocator::offsetOfFreeList() + FreeList::offsetOfNextInterval()), resultGPR, scratchGPR);
zeroPath = branchTestPtr(ResultCondition::NonZero, resultGPR, TrustedImm32(1));
xor64(Address(resultGPR, FreeCell::offsetOfScrambledBits()), scratchGPR);
addSignExtend64(resultGPR, scratchGPR, dataTempRegister);
addUnsignedRightShift64(resultGPR, scratchGPR, TrustedImm32(32), scratchGPR);
storePairPtr(scratchGPR, dataTempRegister, allocatorGPR, TrustedImm32(LocalAllocator::offsetOfFreeList() + FreeList::offsetOfIntervalEnd()));
jump(bumpLabel);
#elif CPU(X86_64)
// On x86_64, we can leverage better support for memory operands to directly interact with the free
// list instead of relying on registers as much.
// Bump allocation (fast path)
loadPtr(Address(allocatorGPR, LocalAllocator::offsetOfFreeList() + FreeList::offsetOfIntervalStart()), resultGPR);
popPath = branchPtr(RelationalCondition::AboveOrEqual, resultGPR, Address(allocatorGPR, LocalAllocator::offsetOfFreeList() + FreeList::offsetOfIntervalEnd()));
auto bumpLabel = label();
if (allocator.isConstant())
add64(TrustedImm32(allocator.allocator().cellSize()), Address(allocatorGPR, LocalAllocator::offsetOfFreeList() + FreeList::offsetOfIntervalStart()));
else {
load32(Address(allocatorGPR, LocalAllocator::offsetOfCellSize()), scratchGPR);
add64(scratchGPR, Address(allocatorGPR, LocalAllocator::offsetOfFreeList() + FreeList::offsetOfIntervalStart()));
}
done = jump();
// Get next interval (slower path)
popPath.link(this);
loadPtr(Address(allocatorGPR, LocalAllocator::offsetOfFreeList() + FreeList::offsetOfNextInterval()), resultGPR);
zeroPath = branchTestPtr(ResultCondition::NonZero, resultGPR, TrustedImm32(1));
load32(Address(allocatorGPR, LocalAllocator::offsetOfFreeList() + FreeList::offsetOfSecret()), scratchGPR);
xor32(Address(resultGPR, FreeCell::offsetOfScrambledBits()), scratchGPR); // Lower 32 bits -> offset to next interval
add64(scratchGPR, Address(allocatorGPR, LocalAllocator::offsetOfFreeList() + FreeList::offsetOfNextInterval()));
load32(Address(allocatorGPR, LocalAllocator::offsetOfFreeList() + FreeList::offsetOfSecret() + 4), scratchGPR);
xor32(Address(resultGPR, FreeCell::offsetOfScrambledBits() + 4), scratchGPR); // Upper 32 bits -> size of interval
storePtr(resultGPR, Address(allocatorGPR, LocalAllocator::offsetOfFreeList() + FreeList::offsetOfIntervalStart()));
addPtr(resultGPR, scratchGPR);
storePtr(scratchGPR, Address(allocatorGPR, LocalAllocator::offsetOfFreeList() + FreeList::offsetOfIntervalEnd()));
jump(bumpLabel);