%PDF-
%PDF-
Mini Shell
Mini Shell
// Copyright 2018 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/codegen/reloc-info.h"
#include "src/base/vlq.h"
#include "src/codegen/assembler-inl.h"
#include "src/codegen/code-reference.h"
#include "src/codegen/external-reference-encoder.h"
#include "src/deoptimizer/deoptimize-reason.h"
#include "src/deoptimizer/deoptimizer.h"
#include "src/heap/heap-write-barrier-inl.h"
#include "src/objects/code-inl.h"
#include "src/snapshot/embedded/embedded-data-inl.h"
namespace v8 {
namespace internal {
using namespace detail;
uint32_t RelocInfoWriter::WriteLongPCJump(uint32_t pc_delta) {
// Return if the pc_delta can fit in kSmallPCDeltaBits bits.
// Otherwise write a variable length PC jump for the bits that do
// not fit in the kSmallPCDeltaBits bits.
if (is_uintn(pc_delta, kSmallPCDeltaBits)) return pc_delta;
WriteMode(RelocInfo::PC_JUMP);
uint32_t pc_jump = pc_delta >> kSmallPCDeltaBits;
DCHECK_GT(pc_jump, 0);
base::VLQEncodeUnsigned(
[this](uint8_t byte) {
*--pos_ = byte;
return pos_;
},
pc_jump);
// Return the remaining kSmallPCDeltaBits of the pc_delta.
return pc_delta & kSmallPCDeltaMask;
}
void RelocInfoWriter::WriteShortTaggedPC(uint32_t pc_delta, int tag) {
// Write a byte of tagged pc-delta, possibly preceded by an explicit pc-jump.
pc_delta = WriteLongPCJump(pc_delta);
*--pos_ = pc_delta << kTagBits | tag;
}
void RelocInfoWriter::WriteShortData(intptr_t data_delta) {
*--pos_ = static_cast<uint8_t>(data_delta);
}
void RelocInfoWriter::WriteMode(RelocInfo::Mode rmode) {
static_assert(RelocInfo::NUMBER_OF_MODES <= (1 << kLongTagBits));
*--pos_ = static_cast<int>((rmode << kTagBits) | kDefaultTag);
}
void RelocInfoWriter::WriteModeAndPC(uint32_t pc_delta, RelocInfo::Mode rmode) {
// Write two-byte tagged pc-delta, possibly preceded by var. length pc-jump.
pc_delta = WriteLongPCJump(pc_delta);
WriteMode(rmode);
*--pos_ = pc_delta;
}
void RelocInfoWriter::WriteIntData(int number) {
for (int i = 0; i < kIntSize; i++) {
*--pos_ = static_cast<uint8_t>(number);
// Signed right shift is arithmetic shift. Tested in test-utils.cc.
number = number >> kBitsPerByte;
}
}
void RelocInfoWriter::Write(const RelocInfo* rinfo) {
RelocInfo::Mode rmode = rinfo->rmode();
#ifdef DEBUG
uint8_t* begin_pos = pos_;
#endif
DCHECK(rinfo->rmode() < RelocInfo::NUMBER_OF_MODES);
DCHECK_GE(rinfo->pc() - reinterpret_cast<Address>(last_pc_), 0);
// Use unsigned delta-encoding for pc.
uint32_t pc_delta =
static_cast<uint32_t>(rinfo->pc() - reinterpret_cast<Address>(last_pc_));
// The two most common modes are given small tags, and usually fit in a byte.
if (rmode == RelocInfo::FULL_EMBEDDED_OBJECT) {
WriteShortTaggedPC(pc_delta, kEmbeddedObjectTag);
} else if (rmode == RelocInfo::CODE_TARGET) {
WriteShortTaggedPC(pc_delta, kCodeTargetTag);
DCHECK_LE(begin_pos - pos_, RelocInfo::kMaxCallSize);
} else if (rmode == RelocInfo::WASM_STUB_CALL) {
WriteShortTaggedPC(pc_delta, kWasmStubCallTag);
} else {
WriteModeAndPC(pc_delta, rmode);
if (RelocInfo::IsDeoptReason(rmode)) {
DCHECK_LT(rinfo->data(), 1 << kBitsPerByte);
WriteShortData(rinfo->data());
} else if (RelocInfo::IsConstPool(rmode) ||
RelocInfo::IsVeneerPool(rmode) || RelocInfo::IsDeoptId(rmode) ||
RelocInfo::IsDeoptPosition(rmode) ||
RelocInfo::IsDeoptNodeId(rmode) ||
RelocInfo::IsRelativeSwitchTableEntry(rmode)) {
WriteIntData(static_cast<int>(rinfo->data()));
}
}
last_pc_ = reinterpret_cast<uint8_t*>(rinfo->pc());
#ifdef DEBUG
DCHECK_LE(begin_pos - pos_, kMaxSize);
#endif
}
template <typename RelocInfoT>
void RelocIteratorBase<RelocInfoT>::AdvanceReadInt() {
int x = 0;
for (int i = 0; i < kIntSize; i++) {
x |= static_cast<int>(*--pos_) << i * kBitsPerByte;
}
rinfo_.data_ = x;
}
template <typename RelocInfoT>
void RelocIteratorBase<RelocInfoT>::AdvanceReadLongPCJump() {
// Read the 32-kSmallPCDeltaBits most significant bits of the
// pc jump as a VLQ encoded integer.
uint32_t pc_jump = base::VLQDecodeUnsigned([this] { return *--pos_; });
// The least significant kSmallPCDeltaBits bits will be added
// later.
rinfo_.pc_ += pc_jump << kSmallPCDeltaBits;
}
template <typename RelocInfoT>
inline void RelocIteratorBase<RelocInfoT>::ReadShortData() {
uint8_t unsigned_b = *pos_;
rinfo_.data_ = unsigned_b;
}
template <typename RelocInfoT>
void RelocIteratorBase<RelocInfoT>::next() {
DCHECK(!done());
// Basically, do the opposite of RelocInfoWriter::Write.
// Reading of data is as far as possible avoided for unwanted modes,
// but we must always update the pc.
//
// We exit this loop by returning when we find a mode we want.
while (pos_ > end_) {
int tag = AdvanceGetTag();
if (tag == kEmbeddedObjectTag) {
ReadShortTaggedPC();
if (SetMode(RelocInfo::FULL_EMBEDDED_OBJECT)) return;
} else if (tag == kCodeTargetTag) {
ReadShortTaggedPC();
if (SetMode(RelocInfo::CODE_TARGET)) return;
} else if (tag == kWasmStubCallTag) {
ReadShortTaggedPC();
if (SetMode(RelocInfo::WASM_STUB_CALL)) return;
} else {
DCHECK_EQ(tag, kDefaultTag);
RelocInfo::Mode rmode = GetMode();
if (rmode == RelocInfo::PC_JUMP) {
AdvanceReadLongPCJump();
} else {
AdvanceReadPC();
if (RelocInfo::IsDeoptReason(rmode)) {
Advance();
if (SetMode(rmode)) {
ReadShortData();
return;
}
} else if (RelocInfo::IsConstPool(rmode) ||
RelocInfo::IsVeneerPool(rmode) ||
RelocInfo::IsDeoptId(rmode) ||
RelocInfo::IsDeoptPosition(rmode) ||
RelocInfo::IsDeoptNodeId(rmode) ||
RelocInfo::IsRelativeSwitchTableEntry(rmode)) {
if (SetMode(rmode)) {
AdvanceReadInt();
return;
}
Advance(kIntSize);
} else if (SetMode(static_cast<RelocInfo::Mode>(rmode))) {
return;
}
}
}
}
done_ = true;
}
RelocIterator::RelocIterator(Tagged<Code> code, int mode_mask)
: RelocIteratorBase<RelocInfo>(
code->instruction_start(), code->constant_pool(),
code->instruction_stream()->relocation_info()->GetDataEndAddress(),
code->instruction_stream()->relocation_info()->GetDataStartAddress(),
mode_mask) {}
RelocIterator::RelocIterator(Tagged<Code> code,
Tagged<InstructionStream> instruction_stream,
Tagged<ByteArray> relocation_info, int mode_mask)
: RelocIteratorBase<RelocInfo>(instruction_stream->instruction_start(),
code->constant_pool(instruction_stream),
relocation_info->GetDataEndAddress(),
relocation_info->GetDataStartAddress(),
mode_mask) {}
RelocIterator::RelocIterator(const CodeReference code_reference)
: RelocIteratorBase<RelocInfo>(
code_reference.instruction_start(), code_reference.constant_pool(),
code_reference.relocation_end(), code_reference.relocation_start(),
kAllModesMask) {}
RelocIterator::RelocIterator(EmbeddedData* embedded_data, Tagged<Code> code,
int mode_mask)
: RelocIteratorBase<RelocInfo>(
embedded_data->InstructionStartOf(code->builtin_id()),
code->constant_pool(), code->relocation_end(),
code->relocation_start(), mode_mask) {}
RelocIterator::RelocIterator(base::Vector<uint8_t> instructions,
base::Vector<const uint8_t> reloc_info,
Address const_pool, int mode_mask)
: RelocIteratorBase<RelocInfo>(
reinterpret_cast<Address>(instructions.begin()), const_pool,
reloc_info.begin() + reloc_info.size(), reloc_info.begin(),
mode_mask) {}
WritableRelocIterator::WritableRelocIterator(
WritableJitAllocation& jit_allocation, Tagged<InstructionStream> istream,
Address constant_pool, int mode_mask)
: RelocIteratorBase<WritableRelocInfo>(
istream->instruction_start(), constant_pool,
istream->unchecked_relocation_info()->GetDataEndAddress(),
istream->unchecked_relocation_info()->GetDataStartAddress(),
mode_mask) {}
WritableRelocIterator::WritableRelocIterator(
WritableJitAllocation& jit_allocation, base::Vector<uint8_t> instructions,
base::Vector<const uint8_t> reloc_info, Address constant_pool,
int mode_mask)
: RelocIteratorBase<WritableRelocInfo>(
reinterpret_cast<Address>(instructions.begin()), constant_pool,
reloc_info.begin() + reloc_info.size(), reloc_info.begin(),
mode_mask) {}
template <typename RelocInfoT>
RelocIteratorBase<RelocInfoT>::RelocIteratorBase(Address pc,
Address constant_pool,
const uint8_t* pos,
const uint8_t* end,
int mode_mask)
: pos_(pos),
end_(end),
rinfo_(pc, RelocInfo::NO_INFO, 0, constant_pool),
mode_mask_(mode_mask) {
// Relocation info is read backwards.
DCHECK_GE(pos_, end_);
if (mode_mask_ == 0) pos_ = end_;
next();
}
// -----------------------------------------------------------------------------
// Implementation of RelocInfo
// static
bool RelocInfo::OffHeapTargetIsCodedSpecially() {
#if defined(V8_TARGET_ARCH_ARM) || defined(V8_TARGET_ARCH_ARM64) || \
defined(V8_TARGET_ARCH_X64)
return false;
#elif defined(V8_TARGET_ARCH_IA32) || defined(V8_TARGET_ARCH_MIPS64) || \
defined(V8_TARGET_ARCH_PPC) || defined(V8_TARGET_ARCH_PPC64) || \
defined(V8_TARGET_ARCH_S390) || defined(V8_TARGET_ARCH_RISCV64) || \
defined(V8_TARGET_ARCH_LOONG64) || defined(V8_TARGET_ARCH_RISCV32)
return true;
#endif
}
Address RelocInfo::wasm_call_address() const {
DCHECK_EQ(rmode_, WASM_CALL);
return Assembler::target_address_at(pc_, constant_pool_);
}
void WritableRelocInfo::set_wasm_call_address(
Address address, ICacheFlushMode icache_flush_mode) {
DCHECK_EQ(rmode_, WASM_CALL);
Assembler::set_target_address_at(pc_, constant_pool_, address,
icache_flush_mode);
}
Address RelocInfo::wasm_stub_call_address() const {
DCHECK_EQ(rmode_, WASM_STUB_CALL);
return Assembler::target_address_at(pc_, constant_pool_);
}
void WritableRelocInfo::set_wasm_stub_call_address(
Address address, ICacheFlushMode icache_flush_mode) {
DCHECK_EQ(rmode_, WASM_STUB_CALL);
Assembler::set_target_address_at(pc_, constant_pool_, address,
icache_flush_mode);
}
void WritableRelocInfo::set_target_address(Address target,
ICacheFlushMode icache_flush_mode) {
DCHECK(IsCodeTargetMode(rmode_) || IsNearBuiltinEntry(rmode_) ||
IsWasmCall(rmode_));
Assembler::set_target_address_at(pc_, constant_pool_, target,
icache_flush_mode);
}
void WritableRelocInfo::set_target_address(Tagged<InstructionStream> host,
Address target,
WriteBarrierMode write_barrier_mode,
ICacheFlushMode icache_flush_mode) {
set_target_address(target, icache_flush_mode);
if (IsCodeTargetMode(rmode_) && !v8_flags.disable_write_barriers) {
Tagged<InstructionStream> target_code =
InstructionStream::FromTargetAddress(target);
WriteBarrierForCode(host, this, target_code, write_barrier_mode);
}
}
void RelocInfo::set_off_heap_target_address(Address target,
ICacheFlushMode icache_flush_mode) {
DCHECK(IsCodeTargetMode(rmode_));
Assembler::set_target_address_at(pc_, constant_pool_, target,
icache_flush_mode);
}
bool RelocInfo::HasTargetAddressAddress() const {
// TODO(jgruber): Investigate whether WASM_CALL is still appropriate on
// non-intel platforms now that wasm code is no longer on the heap.
#if defined(V8_TARGET_ARCH_IA32) || defined(V8_TARGET_ARCH_X64)
static constexpr int kTargetAddressAddressModeMask =
ModeMask(CODE_TARGET) | ModeMask(FULL_EMBEDDED_OBJECT) |
ModeMask(COMPRESSED_EMBEDDED_OBJECT) | ModeMask(EXTERNAL_REFERENCE) |
ModeMask(OFF_HEAP_TARGET) | ModeMask(WASM_CALL) |
ModeMask(WASM_STUB_CALL);
#else
static constexpr int kTargetAddressAddressModeMask =
ModeMask(CODE_TARGET) | ModeMask(RELATIVE_CODE_TARGET) |
ModeMask(FULL_EMBEDDED_OBJECT) | ModeMask(EXTERNAL_REFERENCE) |
ModeMask(OFF_HEAP_TARGET) | ModeMask(WASM_CALL);
#endif
return (ModeMask(rmode_) & kTargetAddressAddressModeMask) != 0;
}
#ifdef ENABLE_DISASSEMBLER
const char* RelocInfo::RelocModeName(RelocInfo::Mode rmode) {
switch (rmode) {
case NO_INFO:
return "no reloc";
case COMPRESSED_EMBEDDED_OBJECT:
return "compressed embedded object";
case FULL_EMBEDDED_OBJECT:
return "full embedded object";
case CODE_TARGET:
return "code target";
case RELATIVE_CODE_TARGET:
return "relative code target";
case EXTERNAL_REFERENCE:
return "external reference";
case INTERNAL_REFERENCE:
return "internal reference";
case INTERNAL_REFERENCE_ENCODED:
return "encoded internal reference";
case RELATIVE_SWITCH_TABLE_ENTRY:
return "relative switch table entry";
case OFF_HEAP_TARGET:
return "off heap target";
case NEAR_BUILTIN_ENTRY:
return "near builtin entry";
case DEOPT_SCRIPT_OFFSET:
return "deopt script offset";
case DEOPT_INLINING_ID:
return "deopt inlining id";
case DEOPT_REASON:
return "deopt reason";
case DEOPT_ID:
return "deopt index";
case DEOPT_NODE_ID:
return "deopt node id";
case CONST_POOL:
return "constant pool";
case VENEER_POOL:
return "veneer pool";
case WASM_CALL:
return "internal wasm call";
case WASM_STUB_CALL:
return "wasm stub call";
case NUMBER_OF_MODES:
case PC_JUMP:
UNREACHABLE();
}
return "unknown relocation type";
}
void RelocInfo::Print(Isolate* isolate, std::ostream& os) {
os << reinterpret_cast<const void*>(pc_) << " " << RelocModeName(rmode_);
if (rmode_ == DEOPT_SCRIPT_OFFSET || rmode_ == DEOPT_INLINING_ID) {
os << " (" << data() << ")";
} else if (rmode_ == DEOPT_REASON) {
os << " ("
<< DeoptimizeReasonToString(static_cast<DeoptimizeReason>(data_)) << ")";
} else if (rmode_ == FULL_EMBEDDED_OBJECT) {
os << " (" << Brief(target_object(isolate)) << ")";
} else if (rmode_ == COMPRESSED_EMBEDDED_OBJECT) {
os << " (" << Brief(target_object(isolate)) << " compressed)";
} else if (rmode_ == EXTERNAL_REFERENCE) {
if (isolate) {
ExternalReferenceEncoder ref_encoder(isolate);
os << " ("
<< ref_encoder.NameOfAddress(isolate, target_external_reference())
<< ") ";
}
os << " (" << reinterpret_cast<const void*>(target_external_reference())
<< ")";
} else if (IsCodeTargetMode(rmode_)) {
const Address code_target = target_address();
Tagged<Code> target_code = Code::FromTargetAddress(code_target);
os << " (" << CodeKindToString(target_code->kind());
if (Builtins::IsBuiltin(target_code)) {
os << " " << Builtins::name(target_code->builtin_id());
}
os << ") (" << reinterpret_cast<const void*>(target_address()) << ")";
} else if (IsConstPool(rmode_)) {
os << " (size " << static_cast<int>(data_) << ")";
} else if (IsWasmStubCall(rmode_)) {
os << " (";
Address addr = target_address();
if (isolate != nullptr) {
Builtin builtin = OffHeapInstructionStream::TryLookupCode(isolate, addr);
os << (Builtins::IsBuiltinId(builtin) ? Builtins::name(builtin)
: "<UNRECOGNIZED>")
<< ") (";
}
os << reinterpret_cast<const void*>(addr) << ")";
}
os << "\n";
}
#endif // ENABLE_DISASSEMBLER
#ifdef VERIFY_HEAP
void RelocInfo::Verify(Isolate* isolate) {
switch (rmode_) {
case COMPRESSED_EMBEDDED_OBJECT:
Object::VerifyPointer(isolate, target_object(isolate));
break;
case FULL_EMBEDDED_OBJECT:
Object::VerifyAnyTagged(isolate, target_object(isolate));
break;
case CODE_TARGET:
case RELATIVE_CODE_TARGET: {
// convert inline target address to code object
Address addr = target_address();
CHECK_NE(addr, kNullAddress);
// Check that we can find the right code object.
Tagged<InstructionStream> code =
InstructionStream::FromTargetAddress(addr);
Tagged<Code> lookup_result =
isolate->heap()->FindCodeForInnerPointer(addr);
CHECK_EQ(code.address(), lookup_result->instruction_stream().address());
break;
}
case INTERNAL_REFERENCE:
case INTERNAL_REFERENCE_ENCODED: {
Address target = target_internal_reference();
Address pc = target_internal_reference_address();
Tagged<Code> lookup_result = isolate->heap()->FindCodeForInnerPointer(pc);
CHECK_GE(target, lookup_result->instruction_start());
CHECK_LT(target, lookup_result->instruction_end());
break;
}
case OFF_HEAP_TARGET: {
Address addr = target_off_heap_target();
CHECK_NE(addr, kNullAddress);
CHECK(Builtins::IsBuiltinId(
OffHeapInstructionStream::TryLookupCode(isolate, addr)));
break;
}
case WASM_STUB_CALL:
case NEAR_BUILTIN_ENTRY: {
Address addr = target_address();
CHECK_NE(addr, kNullAddress);
CHECK(Builtins::IsBuiltinId(
OffHeapInstructionStream::TryLookupCode(isolate, addr)));
break;
}
case EXTERNAL_REFERENCE:
case DEOPT_SCRIPT_OFFSET:
case DEOPT_INLINING_ID:
case DEOPT_REASON:
case DEOPT_ID:
case DEOPT_NODE_ID:
case CONST_POOL:
case VENEER_POOL:
case WASM_CALL:
case NO_INFO:
case RELATIVE_SWITCH_TABLE_ENTRY:
break;
case NUMBER_OF_MODES:
case PC_JUMP:
UNREACHABLE();
}
}
#endif // VERIFY_HEAP
template class EXPORT_TEMPLATE_DEFINE(V8_EXPORT_PRIVATE)
RelocIteratorBase<RelocInfo>;
template class EXPORT_TEMPLATE_DEFINE(V8_EXPORT_PRIVATE)
RelocIteratorBase<WritableRelocInfo>;
} // namespace internal
} // namespace v8
Zerion Mini Shell 1.0