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AssemblyHelpers.cpp
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AssemblyHelpers.cpp
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/*
* Copyright (C) 2011-2022 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 "SuperSampler.h"
#include "ThunkGenerators.h"
#include "UnlinkedCodeBlock.h"
#if ENABLE(WEBASSEMBLY)
#include "WasmContext.h"
#include "WasmMemoryInformation.h"
#include "WasmInstance.h"
#endif
namespace JSC {
namespace AssemblyHelpersInternal {
constexpr bool dumpVerbose = false;
}
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 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)
{
Jump checkJSInt32 = branch64(AboveOrEqual, gpr, GPRInfo::numberTagRegister);
abortWithReason(AHIsNotJSInt32);
checkJSInt32.link(this);
}
void AssemblyHelpers::jitAssertIsJSNumber(GPRReg gpr)
{
Jump checkJSNumber = branchTest64(MacroAssembler::NonZero, gpr, GPRInfo::numberTagRegister);
abortWithReason(AHIsNotJSNumber);
checkJSNumber.link(this);
}
void AssemblyHelpers::jitAssertIsJSDouble(GPRReg gpr)
{
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)
{
Jump checkCell = branchTest64(MacroAssembler::Zero, gpr, GPRInfo::notCellMaskRegister);
abortWithReason(AHIsNotCell);
checkCell.link(this);
}
void AssemblyHelpers::jitAssertTagsInPlace()
{
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)
{
UNUSED_PARAM(gpr);
}
void AssemblyHelpers::jitAssertIsJSInt32(GPRReg gpr)
{
Jump checkJSInt32 = branch32(Equal, gpr, TrustedImm32(JSValue::Int32Tag));
abortWithReason(AHIsNotJSInt32);
checkJSInt32.link(this);
}
void AssemblyHelpers::jitAssertIsJSNumber(GPRReg gpr)
{
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)
{
Jump checkJSDouble = branch32(Below, gpr, TrustedImm32(JSValue::LowestTag));
abortWithReason(AHIsNotJSDouble);
checkJSDouble.link(this);
}
void AssemblyHelpers::jitAssertIsCell(GPRReg gpr)
{
Jump checkCell = branchIfCell(gpr);
abortWithReason(AHIsNotCell);
checkCell.link(this);
}
void AssemblyHelpers::jitAssertTagsInPlace()
{
}
#endif // USE(JSVALUE32_64)
void AssemblyHelpers::jitAssertHasValidCallFrame()
{
Jump checkCFR = branchTestPtr(Zero, GPRInfo::callFrameRegister, TrustedImm32(7));
abortWithReason(AHCallFrameMisaligned);
checkCFR.link(this);
}
void AssemblyHelpers::jitAssertIsNull(GPRReg gpr)
{
Jump checkNull = branchTestPtr(Zero, gpr);
abortWithReason(AHIsNotNull);
checkNull.link(this);
}
void AssemblyHelpers::jitAssertArgumentCountSane()
{
Jump ok = branch32(Below, payloadFor(CallFrameSlot::argumentCountIncludingThis), TrustedImm32(10000000));
abortWithReason(AHInsaneArgumentCount);
ok.link(this);
}
void AssemblyHelpers::jitAssertCodeBlockOnCallFrameWithType(GPRReg scratchGPR, JITType type)
{
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 (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)
{
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)
{
if (UNLIKELY(Options::useExceptionFuzz()))
callExceptionFuzz(vm);
if (width == FarJumpWidth)
kind = (kind == NormalExceptionCheck ? InvertedExceptionCheck : NormalExceptionCheck);
Jump result;
#if USE(JSVALUE64)
result = branchTest64(kind == NormalExceptionCheck ? NonZero : Zero, AbsoluteAddress(vm.addressOfException()));
#elif USE(JSVALUE32_64)
result = branch32(kind == NormalExceptionCheck ? NotEqual : Equal, AbsoluteAddress(vm.addressOfException()), TrustedImm32(0));
#endif
if (width == NormalJumpWidth)
return result;
PatchableJump realJump = patchableJump();
result.link(this);
return realJump.m_jump;
}
AssemblyHelpers::Jump AssemblyHelpers::emitNonPatchableExceptionCheck(VM& vm)
{
if (UNLIKELY(Options::useExceptionFuzz()))
callExceptionFuzz(vm);
Jump result;
#if USE(JSVALUE64)
result = branchTest64(NonZero, AbsoluteAddress(vm.addressOfException()));
#elif USE(JSVALUE32_64)
result = branch32(NotEqual, AbsoluteAddress(vm.addressOfException()), TrustedImm32(0));
#endif
return result;
}
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)
{
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)
{
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)));
}
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(g_jscConfig.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)
{
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 done;
if (allocator.isConstant())
move(TrustedImmPtr(allocator.allocator().localAllocator()), allocatorGPR);
load32(Address(allocatorGPR, LocalAllocator::offsetOfFreeList() + FreeList::offsetOfRemaining()), resultGPR);
popPath = branchTest32(Zero, resultGPR);
if (allocator.isConstant())
add32(TrustedImm32(-allocator.allocator().cellSize()), resultGPR, scratchGPR);
else {
move(resultGPR, scratchGPR);
sub32(Address(allocatorGPR, LocalAllocator::offsetOfCellSize()), scratchGPR);
}
negPtr(resultGPR);
store32(scratchGPR, Address(allocatorGPR, LocalAllocator::offsetOfFreeList() + FreeList::offsetOfRemaining()));
Address payloadEndAddr = Address(allocatorGPR, LocalAllocator::offsetOfFreeList() + FreeList::offsetOfPayloadEnd());
addPtr(payloadEndAddr, resultGPR);
done = jump();
popPath.link(this);
ASSERT(static_cast<ptrdiff_t>(LocalAllocator::offsetOfFreeList() + FreeList::offsetOfScrambledHead() + sizeof(void*)) == static_cast<ptrdiff_t>(LocalAllocator::offsetOfFreeList() + FreeList::offsetOfSecret()));
if constexpr (isARM64()) {
loadPairPtr(allocatorGPR, TrustedImm32(LocalAllocator::offsetOfFreeList() + FreeList::offsetOfScrambledHead()), resultGPR, scratchGPR);
xorPtr(scratchGPR, resultGPR);
} else {
loadPtr(Address(allocatorGPR, LocalAllocator::offsetOfFreeList() + FreeList::offsetOfScrambledHead()), resultGPR);
xorPtr(Address(allocatorGPR, LocalAllocator::offsetOfFreeList() + FreeList::offsetOfSecret()), resultGPR);
}
slowPath.append(branchTestPtr(Zero, resultGPR));
// The object is half-allocated: we have what we know is a fresh object, but
// it's still on the GC's free list.
loadPtr(Address(resultGPR, FreeCell::offsetOfScrambledNext()), scratchGPR);
storePtr(scratchGPR, Address(allocatorGPR, LocalAllocator::offsetOfFreeList() + FreeList::offsetOfScrambledHead()));
done.link(this);
}
void AssemblyHelpers::emitAllocate(GPRReg resultGPR, const JITAllocator& allocator, GPRReg allocatorGPR, GPRReg scratchGPR, JumpList& slowPath)
{
if (allocator.isConstant()) {
if (!allocator.allocator()) {
slowPath.append(jump());
return;
}
} else
slowPath.append(branchTestPtr(Zero, allocatorGPR));
emitAllocateWithNonNullAllocator(resultGPR, allocator, allocatorGPR, scratchGPR, slowPath);
}
void AssemblyHelpers::emitAllocateVariableSized(GPRReg resultGPR, CompleteSubspace& subspace, GPRReg allocationSize, GPRReg scratchGPR1, GPRReg scratchGPR2, JumpList& slowPath)
{
static_assert(!(MarkedSpace::sizeStep & (MarkedSpace::sizeStep - 1)), "MarkedSpace::sizeStep must be a power of two.");
unsigned stepShift = getLSBSet(MarkedSpace::sizeStep);
add32(TrustedImm32(MarkedSpace::sizeStep - 1), allocationSize, scratchGPR1);
urshift32(TrustedImm32(stepShift), scratchGPR1);
slowPath.append(branch32(Above, scratchGPR1, TrustedImm32(MarkedSpace::largeCutoff >> stepShift)));
move(TrustedImmPtr(subspace.allocatorForSizeStep()), scratchGPR2);
loadPtr(BaseIndex(scratchGPR2, scratchGPR1, ScalePtr), scratchGPR1);
emitAllocate(resultGPR, JITAllocator::variable(), scratchGPR1, scratchGPR2, slowPath);
}
void AssemblyHelpers::restoreCalleeSavesFromEntryFrameCalleeSavesBuffer(EntryFrame*& topEntryFrame)
{
#if NUMBER_OF_CALLEE_SAVES_REGISTERS > 0
RegisterAtOffsetList* allCalleeSaves = RegisterSetBuilder::vmCalleeSaveRegisterOffsets();
auto dontRestoreRegisters = RegisterSetBuilder::stackRegisters();
unsigned registerCount = allCalleeSaves->registerCount();
if constexpr (AssemblyHelpersInternal::dumpVerbose)
JIT_COMMENT(*this, "restoreCalleeSavesFromEntryFrameCalleeSavesBuffer ", *allCalleeSaves, " skip: ", dontRestoreRegisters);
else
JIT_COMMENT(*this, "restoreCalleeSavesFromEntryFrameCalleeSavesBuffer");
GPRReg scratch = InvalidGPRReg;
unsigned scratchGPREntryIndex = 0;
#if CPU(ARM64)
// We don't need a second scratch GPR, but we'll also defer restoring this
// GPR (in the next slot after the scratch) so that we can restore them together
// later using a loadPair64.
GPRReg unusedNextSlotGPR = InvalidGPRReg;
#endif
// Use the first GPR entry's register as our baseGPR.
for (unsigned i = 0; i < registerCount; i++) {
RegisterAtOffset entry = allCalleeSaves->at(i);
if (dontRestoreRegisters.contains(entry.reg(), IgnoreVectors))
continue;
if (entry.reg().isGPR()) {
#if CPU(ARM64)
if (i + 1 < registerCount) {
RegisterAtOffset entry2 = allCalleeSaves->at(i + 1);
if (!dontRestoreRegisters.contains(entry2.reg(), IgnoreVectors)
&& entry2.reg().isGPR()
&& entry2.offset() == entry.offset() + static_cast<ptrdiff_t>(sizeof(CPURegister))) {
scratchGPREntryIndex = i;
scratch = entry.reg().gpr();
unusedNextSlotGPR = entry2.reg().gpr();
break;
}
}
#else
scratchGPREntryIndex = i;
scratch = entry.reg().gpr();
break;
#endif
}
}
ASSERT(scratch != InvalidGPRReg);
RegisterSet skipList;
skipList.merge(dontRestoreRegisters);
// Skip the scratch register(s). We'll restore them later.
skipList.add(scratch, IgnoreVectors);
#if CPU(ARM64)
RELEASE_ASSERT(unusedNextSlotGPR != InvalidGPRReg);
skipList.add(unusedNextSlotGPR, IgnoreVectors);
#endif
loadPtr(&topEntryFrame, scratch);
restoreCalleeSavesFromVMEntryFrameCalleeSavesBufferImpl(scratch, skipList);
// Restore the callee save value of the scratch.
RegisterAtOffset entry = allCalleeSaves->at(scratchGPREntryIndex);
ASSERT(!dontRestoreRegisters.contains(entry.reg(), IgnoreVectors));
ASSERT(entry.reg().isGPR());
ASSERT(scratch == entry.reg().gpr());
#if CPU(ARM64)
RegisterAtOffset entry2 = allCalleeSaves->at(scratchGPREntryIndex + 1);
ASSERT_UNUSED(entry2, !dontRestoreRegisters.contains(entry2.reg(), IgnoreVectors));
ASSERT(entry2.reg().isGPR());
ASSERT(unusedNextSlotGPR == entry2.reg().gpr());
loadPair64(scratch, TrustedImm32(entry.offset()), scratch, unusedNextSlotGPR);
#else
loadPtr(Address(scratch, entry.offset()), scratch);
#endif
#else
UNUSED_PARAM(topEntryFrame);
#endif // NUMBER_OF_CALLEE_SAVES_REGISTERS > 0
}
void AssemblyHelpers::restoreCalleeSavesFromVMEntryFrameCalleeSavesBuffer(GPRReg vmGPR, GPRReg scratchGPR)
{
#if NUMBER_OF_CALLEE_SAVES_REGISTERS > 0
loadPtr(Address(vmGPR, VM::topEntryFrameOffset()), scratchGPR);
restoreCalleeSavesFromVMEntryFrameCalleeSavesBufferImpl(scratchGPR, RegisterSetBuilder::stackRegisters());
#else
UNUSED_PARAM(vmGPR);
#endif // NUMBER_OF_CALLEE_SAVES_REGISTERS > 0
}
void AssemblyHelpers::restoreCalleeSavesFromVMEntryFrameCalleeSavesBufferImpl(GPRReg entryFrameGPR, const RegisterSet& skipList)
{
#if NUMBER_OF_CALLEE_SAVES_REGISTERS > 0
addPtr(TrustedImm32(EntryFrame::calleeSaveRegistersBufferOffset()), entryFrameGPR);
RegisterAtOffsetList* allCalleeSaves = RegisterSetBuilder::vmCalleeSaveRegisterOffsets();
if constexpr (AssemblyHelpersInternal::dumpVerbose)
JIT_COMMENT(*this, "restoreCalleeSavesFromVMEntryFrameCalleeSavesBufferImpl ", entryFrameGPR, " callee saves: ", *allCalleeSaves, " skip: ", skipList);
else
JIT_COMMENT(*this, "restoreCalleeSavesFromVMEntryFrameCalleeSavesBufferImpl");
unsigned registerCount = allCalleeSaves->registerCount();
LoadRegSpooler spooler(*this, entryFrameGPR);
// Restore all callee saves except for the scratch.
unsigned i = 0;
for (; i < registerCount; i++) {
RegisterAtOffset entry = allCalleeSaves->at(i);
if (skipList.contains(entry.reg(), IgnoreVectors))
continue;
if (!entry.reg().isGPR())
break;
spooler.loadGPR(entry);
}
spooler.finalizeGPR();
for (; i < registerCount; i++) {
RegisterAtOffset entry = allCalleeSaves->at(i);
if (skipList.contains(entry.reg(), IgnoreVectors))
continue;
ASSERT(!entry.reg().isGPR());
spooler.loadFPR(entry);
}
spooler.finalizeFPR();
#else
UNUSED_PARAM(vmGPR);
UNUSED_PARAM(skipList);
#endif // NUMBER_OF_CALLEE_SAVES_REGISTERS > 0
}
void AssemblyHelpers::emitVirtualCall(VM& vm, JSGlobalObject* globalObject, CallLinkInfo* info)
{
move(TrustedImmPtr(globalObject), GPRInfo::regT3);
move(TrustedImmPtr(info), GPRInfo::regT2);
emitVirtualCallWithoutMovingGlobalObject(vm, GPRInfo::regT2, info->callMode());
}
void AssemblyHelpers::emitVirtualCallWithoutMovingGlobalObject(VM& vm, GPRReg callLinkInfoGPR, CallMode callMode)
{
move(callLinkInfoGPR, GPRInfo::regT2);
Call call = nearCall();
addLinkTask([=, &vm] (LinkBuffer& linkBuffer) {
auto callLocation = linkBuffer.locationOfNearCall<JITCompilationPtrTag>(call);
linkBuffer.addMainThreadFinalizationTask([=, &vm] () {
MacroAssemblerCodeRef<JITStubRoutinePtrTag> virtualThunk = vm.getCTIVirtualCall(callMode);
MacroAssembler::repatchNearCall(callLocation, CodeLocationLabel<JITStubRoutinePtrTag>(virtualThunk.code()));
});
});
}
#if USE(JSVALUE64)
void AssemblyHelpers::wangsInt64Hash(GPRReg inputAndResult, GPRReg scratch)
{
GPRReg input = inputAndResult;
// key += ~(key << 32);
move(input, scratch);
lshift64(TrustedImm32(32), scratch);
not64(scratch);
add64(scratch, input);
// key ^= (key >> 22);
move(input, scratch);
urshift64(TrustedImm32(22), scratch);
xor64(scratch, input);
// key += ~(key << 13);
move(input, scratch);
lshift64(TrustedImm32(13), scratch);
not64(scratch);
add64(scratch, input);
// key ^= (key >> 8);
move(input, scratch);
urshift64(TrustedImm32(8), scratch);
xor64(scratch, input);
// key += (key << 3);
move(input, scratch);
lshift64(TrustedImm32(3), scratch);
add64(scratch, input);
// key ^= (key >> 15);
move(input, scratch);
urshift64(TrustedImm32(15), scratch);
xor64(scratch, input);
// key += ~(key << 27);
move(input, scratch);
lshift64(TrustedImm32(27), scratch);
not64(scratch);
add64(scratch, input);
// key ^= (key >> 31);
move(input, scratch);
urshift64(TrustedImm32(31), scratch);
xor64(scratch, input);
// return static_cast<unsigned>(result)
void* mask = bitwise_cast<void*>(static_cast<uintptr_t>(UINT_MAX));
and64(TrustedImmPtr(mask), inputAndResult);
}
#endif // USE(JSVALUE64)
void AssemblyHelpers::emitConvertValueToBoolean(VM& vm, JSValueRegs value, GPRReg result, GPRReg scratchIfShouldCheckMasqueradesAsUndefined, FPRReg valueAsFPR, FPRReg tempFPR, bool shouldCheckMasqueradesAsUndefined, JSGlobalObject* globalObject, bool invert)
{
// Implements the following control flow structure:
// if (value is cell) {
// if (value is string or value is HeapBigInt)
// result = !!value->length
// else {
// do evil things for masquerades-as-undefined
// result = true
// }
// } else if (value is int32) {
// result = !!unboxInt32(value)
// } else if (value is number) {
// result = !!unboxDouble(value)
// } else if (value is BigInt32) {
// result = !!unboxBigInt32(value)
// } else {
// result = value == jsTrue
// }
JumpList done;
auto notCell = branchIfNotCell(value);
auto isString = branchIfString(value.payloadGPR());
auto isHeapBigInt = branchIfHeapBigInt(value.payloadGPR());
if (shouldCheckMasqueradesAsUndefined) {
ASSERT(scratchIfShouldCheckMasqueradesAsUndefined != InvalidGPRReg);
JumpList isNotMasqueradesAsUndefined;
isNotMasqueradesAsUndefined.append(branchTest8(Zero, Address(value.payloadGPR(), JSCell::typeInfoFlagsOffset()), TrustedImm32(MasqueradesAsUndefined)));
emitLoadStructure(vm, value.payloadGPR(), result);
move(TrustedImmPtr(globalObject), scratchIfShouldCheckMasqueradesAsUndefined);
isNotMasqueradesAsUndefined.append(branchPtr(NotEqual, Address(result, Structure::globalObjectOffset()), scratchIfShouldCheckMasqueradesAsUndefined));
// We act like we are "undefined" here.
move(invert ? TrustedImm32(1) : TrustedImm32(0), result);
done.append(jump());
isNotMasqueradesAsUndefined.link(this);
}
move(invert ? TrustedImm32(0) : TrustedImm32(1), result);
done.append(jump());
isString.link(this);
move(TrustedImmPtr(jsEmptyString(vm)), result);
comparePtr(invert ? Equal : NotEqual, value.payloadGPR(), result, result);
done.append(jump());
isHeapBigInt.link(this);
load32(Address(value.payloadGPR(), JSBigInt::offsetOfLength()), result);
compare32(invert ? Equal : NotEqual, result, TrustedImm32(0), result);
done.append(jump());
notCell.link(this);
auto notInt32 = branchIfNotInt32(value);
compare32(invert ? Equal : NotEqual, value.payloadGPR(), TrustedImm32(0), result);
done.append(jump());
notInt32.link(this);
auto notDouble = branchIfNotDoubleKnownNotInt32(value);
#if USE(JSVALUE64)
unboxDouble(value.gpr(), result, valueAsFPR);
#else
unboxDouble(value, valueAsFPR);
#endif
move(invert ? TrustedImm32(1) : TrustedImm32(0), result);
done.append(branchDoubleZeroOrNaN(valueAsFPR, tempFPR));
move(invert ? TrustedImm32(0) : TrustedImm32(1), result);
done.append(jump());
notDouble.link(this);
#if USE(BIGINT32)
auto isNotBigInt32 = branchIfNotBigInt32(value.gpr(), result);
move(value.gpr(), result);
urshift64(TrustedImm32(16), result);
compare32(invert ? Equal : NotEqual, result, TrustedImm32(0), result);
done.append(jump());
isNotBigInt32.link(this);
#endif // USE(BIGINT32)
#if USE(JSVALUE64)
compare64(invert ? NotEqual : Equal, value.gpr(), TrustedImm32(JSValue::ValueTrue), result);
#else
move(invert ? TrustedImm32(1) : TrustedImm32(0), result);
done.append(branchIfNotBoolean(value, InvalidGPRReg));
compare32(invert ? Equal : NotEqual, value.payloadGPR(), TrustedImm32(0), result);
#endif
done.link(this);
}
AssemblyHelpers::JumpList AssemblyHelpers::branchIfValue(VM& vm, JSValueRegs value, GPRReg scratch, GPRReg scratchIfShouldCheckMasqueradesAsUndefined, FPRReg valueAsFPR, FPRReg tempFPR, bool shouldCheckMasqueradesAsUndefined, std::variant<JSGlobalObject*, GPRReg> globalObject, bool invert)
{
// Implements the following control flow structure:
// if (value is cell) {
// if (value is string or value is HeapBigInt)
// result = !!value->length
// else {
// do evil things for masquerades-as-undefined
// result = true
// }
// } else if (value is int32) {
// result = !!unboxInt32(value)
// } else if (value is number) {
// result = !!unboxDouble(value)
// } else if (value is BigInt32) {
// result = !!unboxBigInt32(value)
// } else {
// result = value == jsTrue
// }
JumpList done;
JumpList truthy;
auto notCell = branchIfNotCell(value);
auto isString = branchIfString(value.payloadGPR());
auto isHeapBigInt = branchIfHeapBigInt(value.payloadGPR());
if (shouldCheckMasqueradesAsUndefined) {
ASSERT(scratchIfShouldCheckMasqueradesAsUndefined != InvalidGPRReg);
JumpList isNotMasqueradesAsUndefined;
isNotMasqueradesAsUndefined.append(branchTest8(Zero, Address(value.payloadGPR(), JSCell::typeInfoFlagsOffset()), TrustedImm32(MasqueradesAsUndefined)));
emitLoadStructure(vm, value.payloadGPR(), scratch);
if (std::holds_alternative<JSGlobalObject*>(globalObject))
move(TrustedImmPtr(std::get<JSGlobalObject*>(globalObject)), scratchIfShouldCheckMasqueradesAsUndefined);
else
move(std::get<GPRReg>(globalObject), scratchIfShouldCheckMasqueradesAsUndefined);
isNotMasqueradesAsUndefined.append(branchPtr(NotEqual, Address(scratch, Structure::globalObjectOffset()), scratchIfShouldCheckMasqueradesAsUndefined));