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Diffstat (limited to 'deps/v8/src/reloc-info.cc')
| -rw-r--r-- | deps/v8/src/reloc-info.cc | 540 |
1 files changed, 540 insertions, 0 deletions
diff --git a/deps/v8/src/reloc-info.cc b/deps/v8/src/reloc-info.cc new file mode 100644 index 0000000000..ec4a1c679d --- /dev/null +++ b/deps/v8/src/reloc-info.cc @@ -0,0 +1,540 @@ +// 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/reloc-info.h" + +#include "src/assembler-arch-inl.h" +#include "src/code-stubs.h" +#include "src/deoptimize-reason.h" +#include "src/deoptimizer.h" +#include "src/heap/heap-write-barrier-inl.h" +#include "src/objects/code-inl.h" +#include "src/snapshot/snapshot.h" + +namespace v8 { +namespace internal { + +const char* const RelocInfo::kFillerCommentString = "DEOPTIMIZATION PADDING"; + +// ----------------------------------------------------------------------------- +// Implementation of RelocInfoWriter and RelocIterator +// +// Relocation information is written backwards in memory, from high addresses +// towards low addresses, byte by byte. Therefore, in the encodings listed +// below, the first byte listed it at the highest address, and successive +// bytes in the record are at progressively lower addresses. +// +// Encoding +// +// The most common modes are given single-byte encodings. Also, it is +// easy to identify the type of reloc info and skip unwanted modes in +// an iteration. +// +// The encoding relies on the fact that there are fewer than 14 +// different relocation modes using standard non-compact encoding. +// +// The first byte of a relocation record has a tag in its low 2 bits: +// Here are the record schemes, depending on the low tag and optional higher +// tags. +// +// Low tag: +// 00: embedded_object: [6-bit pc delta] 00 +// +// 01: code_target: [6-bit pc delta] 01 +// +// 10: wasm_stub_call: [6-bit pc delta] 10 +// +// 11: long_record [6 bit reloc mode] 11 +// followed by pc delta +// followed by optional data depending on type. +// +// If a pc delta exceeds 6 bits, it is split into a remainder that fits into +// 6 bits and a part that does not. The latter is encoded as a long record +// with PC_JUMP as pseudo reloc info mode. The former is encoded as part of +// the following record in the usual way. The long pc jump record has variable +// length: +// pc-jump: [PC_JUMP] 11 +// [7 bits data] 0 +// ... +// [7 bits data] 1 +// (Bits 6..31 of pc delta, with leading zeroes +// dropped, and last non-zero chunk tagged with 1.) + +const int kTagBits = 2; +const int kTagMask = (1 << kTagBits) - 1; +const int kLongTagBits = 6; + +const int kEmbeddedObjectTag = 0; +const int kCodeTargetTag = 1; +const int kWasmStubCallTag = 2; +const int kDefaultTag = 3; + +const int kSmallPCDeltaBits = kBitsPerByte - kTagBits; +const int kSmallPCDeltaMask = (1 << kSmallPCDeltaBits) - 1; +const int RelocInfo::kMaxSmallPCDelta = kSmallPCDeltaMask; + +const int kChunkBits = 7; +const int kChunkMask = (1 << kChunkBits) - 1; +const int kLastChunkTagBits = 1; +const int kLastChunkTagMask = 1; +const int kLastChunkTag = 1; + +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); + // Write kChunkBits size chunks of the pc_jump. + for (; pc_jump > 0; pc_jump = pc_jump >> kChunkBits) { + byte b = pc_jump & kChunkMask; + *--pos_ = b << kLastChunkTagBits; + } + // Tag the last chunk so it can be identified. + *pos_ = *pos_ | kLastChunkTag; + // 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<byte>(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<byte>(number); + // Signed right shift is arithmetic shift. Tested in test-utils.cc. + number = number >> kBitsPerByte; + } +} + +void RelocInfoWriter::WriteData(intptr_t data_delta) { + for (int i = 0; i < kIntptrSize; i++) { + *--pos_ = static_cast<byte>(data_delta); + // Signed right shift is arithmetic shift. Tested in test-utils.cc. + data_delta = data_delta >> kBitsPerByte; + } +} + +void RelocInfoWriter::Write(const RelocInfo* rinfo) { + RelocInfo::Mode rmode = rinfo->rmode(); +#ifdef DEBUG + byte* 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::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::IsComment(rmode)) { + WriteData(rinfo->data()); + } else 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)) { + WriteIntData(static_cast<int>(rinfo->data())); + } + } + last_pc_ = reinterpret_cast<byte*>(rinfo->pc()); +#ifdef DEBUG + DCHECK_LE(begin_pos - pos_, kMaxSize); +#endif +} + +inline int RelocIterator::AdvanceGetTag() { return *--pos_ & kTagMask; } + +inline RelocInfo::Mode RelocIterator::GetMode() { + return static_cast<RelocInfo::Mode>((*pos_ >> kTagBits) & + ((1 << kLongTagBits) - 1)); +} + +inline void RelocIterator::ReadShortTaggedPC() { + rinfo_.pc_ += *pos_ >> kTagBits; +} + +inline void RelocIterator::AdvanceReadPC() { rinfo_.pc_ += *--pos_; } + +void RelocIterator::AdvanceReadInt() { + int x = 0; + for (int i = 0; i < kIntSize; i++) { + x |= static_cast<int>(*--pos_) << i * kBitsPerByte; + } + rinfo_.data_ = x; +} + +void RelocIterator::AdvanceReadData() { + intptr_t x = 0; + for (int i = 0; i < kIntptrSize; i++) { + x |= static_cast<intptr_t>(*--pos_) << i * kBitsPerByte; + } + rinfo_.data_ = x; +} + +void RelocIterator::AdvanceReadLongPCJump() { + // Read the 32-kSmallPCDeltaBits most significant bits of the + // pc jump in kChunkBits bit chunks and shift them into place. + // Stop when the last chunk is encountered. + uint32_t pc_jump = 0; + for (int i = 0; i < kIntSize; i++) { + byte pc_jump_part = *--pos_; + pc_jump |= (pc_jump_part >> kLastChunkTagBits) << i * kChunkBits; + if ((pc_jump_part & kLastChunkTagMask) == 1) break; + } + // The least significant kSmallPCDeltaBits bits will be added + // later. + rinfo_.pc_ += pc_jump << kSmallPCDeltaBits; +} + +inline void RelocIterator::ReadShortData() { + uint8_t unsigned_b = *pos_; + rinfo_.data_ = unsigned_b; +} + +void RelocIterator::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::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::IsComment(rmode)) { + if (SetMode(rmode)) { + AdvanceReadData(); + return; + } + Advance(kIntptrSize); + } else if (RelocInfo::IsDeoptReason(rmode)) { + Advance(); + if (SetMode(rmode)) { + ReadShortData(); + return; + } + } else if (RelocInfo::IsConstPool(rmode) || + RelocInfo::IsVeneerPool(rmode) || + RelocInfo::IsDeoptId(rmode) || + RelocInfo::IsDeoptPosition(rmode)) { + if (SetMode(rmode)) { + AdvanceReadInt(); + return; + } + Advance(kIntSize); + } else if (SetMode(static_cast<RelocInfo::Mode>(rmode))) { + return; + } + } + } + } + done_ = true; +} + +RelocIterator::RelocIterator(Code* code, int mode_mask) + : RelocIterator(code, code->raw_instruction_start(), code->constant_pool(), + code->relocation_end(), code->relocation_start(), + mode_mask) {} + +RelocIterator::RelocIterator(const CodeReference code_reference, int mode_mask) + : RelocIterator(nullptr, code_reference.instruction_start(), + code_reference.constant_pool(), + code_reference.relocation_end(), + code_reference.relocation_start(), mode_mask) {} + +RelocIterator::RelocIterator(EmbeddedData* embedded_data, Code* code, + int mode_mask) + : RelocIterator( + code, embedded_data->InstructionStartOfBuiltin(code->builtin_index()), + code->constant_pool(), + code->relocation_start() + code->relocation_size(), + code->relocation_start(), mode_mask) {} + +RelocIterator::RelocIterator(const CodeDesc& desc, int mode_mask) + : RelocIterator(nullptr, reinterpret_cast<Address>(desc.buffer), 0, + desc.buffer + desc.buffer_size, + desc.buffer + desc.buffer_size - desc.reloc_size, + mode_mask) {} + +RelocIterator::RelocIterator(Vector<byte> instructions, + Vector<const byte> reloc_info, Address const_pool, + int mode_mask) + : RelocIterator(nullptr, reinterpret_cast<Address>(instructions.start()), + const_pool, reloc_info.start() + reloc_info.size(), + reloc_info.start(), mode_mask) {} + +RelocIterator::RelocIterator(Code* host, Address pc, Address constant_pool, + const byte* pos, const byte* end, int mode_mask) + : pos_(pos), end_(end), mode_mask_(mode_mask) { + // Relocation info is read backwards. + DCHECK_GE(pos_, end_); + rinfo_.host_ = host; + rinfo_.pc_ = pc; + rinfo_.constant_pool_ = constant_pool; + 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_MIPS) || \ + defined(V8_TARGET_ARCH_MIPS64) || defined(V8_TARGET_ARCH_PPC) || \ + defined(V8_TARGET_ARCH_S390) + return true; +#endif +} + +Address RelocInfo::wasm_call_address() const { + DCHECK_EQ(rmode_, WASM_CALL); + return Assembler::target_address_at(pc_, constant_pool_); +} + +void RelocInfo::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 RelocInfo::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 RelocInfo::set_target_address(Address target, + WriteBarrierMode write_barrier_mode, + ICacheFlushMode icache_flush_mode) { + DCHECK(IsCodeTargetMode(rmode_) || IsRuntimeEntry(rmode_) || + IsWasmCall(rmode_)); + Assembler::set_target_address_at(pc_, constant_pool_, target, + icache_flush_mode); + if (write_barrier_mode == UPDATE_WRITE_BARRIER && host() != nullptr && + IsCodeTargetMode(rmode_)) { + Code* target_code = Code::GetCodeFromTargetAddress(target); + MarkingBarrierForCode(host(), this, target_code); + } +} + +bool RelocInfo::RequiresRelocationAfterCodegen(const CodeDesc& desc) { + RelocIterator it(desc, RelocInfo::PostCodegenRelocationMask()); + return !it.done(); +} + +bool RelocInfo::RequiresRelocation(Code* code) { + RelocIterator it(code, RelocInfo::kApplyMask); + return !it.done(); +} + +#ifdef ENABLE_DISASSEMBLER +const char* RelocInfo::RelocModeName(RelocInfo::Mode rmode) { + switch (rmode) { + case NONE: + return "no reloc"; + case EMBEDDED_OBJECT: + return "embedded object"; + case CODE_TARGET: + return "code target"; + case RELATIVE_CODE_TARGET: + return "relative code target"; + case RUNTIME_ENTRY: + return "runtime entry"; + case COMMENT: + return "comment"; + case EXTERNAL_REFERENCE: + return "external reference"; + case INTERNAL_REFERENCE: + return "internal reference"; + case INTERNAL_REFERENCE_ENCODED: + return "encoded internal reference"; + case OFF_HEAP_TARGET: + return "off heap target"; + 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 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 JS_TO_WASM_CALL: + return "js to wasm call"; + case NUMBER_OF_MODES: + case PC_JUMP: + UNREACHABLE(); + } + return "unknown relocation type"; +} + +void RelocInfo::Print(Isolate* isolate, std::ostream& os) { // NOLINT + os << reinterpret_cast<const void*>(pc_) << " " << RelocModeName(rmode_); + if (IsComment(rmode_)) { + os << " (" << reinterpret_cast<char*>(data_) << ")"; + } else 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_ == EMBEDDED_OBJECT) { + os << " (" << Brief(target_object()) << ")"; + } 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(); + Code* code = Code::GetCodeFromTargetAddress(code_target); + DCHECK(code->IsCode()); + os << " (" << Code::Kind2String(code->kind()); + if (Builtins::IsBuiltin(code)) { + os << " " << Builtins::name(code->builtin_index()); + } else if (code->kind() == Code::STUB) { + os << " " << CodeStub::MajorName(CodeStub::GetMajorKey(code)); + } + os << ") (" << reinterpret_cast<const void*>(target_address()) << ")"; + } else if (IsRuntimeEntry(rmode_) && isolate->deoptimizer_data() != nullptr) { + // Deoptimization bailouts are stored as runtime entries. + DeoptimizeKind type; + if (Deoptimizer::IsDeoptimizationEntry(isolate, target_address(), &type)) { + int id = GetDeoptimizationId(isolate, type); + os << " (" << Deoptimizer::MessageFor(type) << " deoptimization bailout " + << id << ")"; + } + } else if (IsConstPool(rmode_)) { + os << " (size " << static_cast<int>(data_) << ")"; + } + + os << "\n"; +} +#endif // ENABLE_DISASSEMBLER + +#ifdef VERIFY_HEAP +void RelocInfo::Verify(Isolate* isolate) { + switch (rmode_) { + case EMBEDDED_OBJECT: + Object::VerifyPointer(isolate, target_object()); + 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. + Code* code = Code::GetCodeFromTargetAddress(addr); + Object* found = isolate->FindCodeObject(addr); + CHECK(found->IsCode()); + CHECK(code->address() == HeapObject::cast(found)->address()); + break; + } + case INTERNAL_REFERENCE: + case INTERNAL_REFERENCE_ENCODED: { + Address target = target_internal_reference(); + Address pc = target_internal_reference_address(); + Code* code = Code::cast(isolate->FindCodeObject(pc)); + CHECK(target >= code->InstructionStart()); + CHECK(target <= code->InstructionEnd()); + break; + } + case OFF_HEAP_TARGET: { + Address addr = target_off_heap_target(); + CHECK_NE(addr, kNullAddress); + CHECK_NOT_NULL(InstructionStream::TryLookupCode(isolate, addr)); + break; + } + case RUNTIME_ENTRY: + case COMMENT: + case EXTERNAL_REFERENCE: + case DEOPT_SCRIPT_OFFSET: + case DEOPT_INLINING_ID: + case DEOPT_REASON: + case DEOPT_ID: + case CONST_POOL: + case VENEER_POOL: + case WASM_CALL: + case WASM_STUB_CALL: + case JS_TO_WASM_CALL: + case NONE: + break; + case NUMBER_OF_MODES: + case PC_JUMP: + UNREACHABLE(); + break; + } +} +#endif // VERIFY_HEAP + +} // namespace internal +} // namespace v8 |