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// Copyright 2011 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/disassembler.h"
#include <memory>
#include <unordered_map>
#include <vector>
#include "src/assembler-inl.h"
#include "src/code-comments.h"
#include "src/code-reference.h"
#include "src/debug/debug.h"
#include "src/deoptimizer.h"
#include "src/disasm.h"
#include "src/ic/ic.h"
#include "src/isolate-data.h"
#include "src/macro-assembler.h"
#include "src/objects-inl.h"
#include "src/snapshot/embedded-data.h"
#include "src/snapshot/serializer-common.h"
#include "src/string-stream.h"
#include "src/wasm/wasm-code-manager.h"
#include "src/wasm/wasm-engine.h"
namespace v8 {
namespace internal {
#ifdef ENABLE_DISASSEMBLER
class V8NameConverter: public disasm::NameConverter {
public:
explicit V8NameConverter(Isolate* isolate, CodeReference code = {})
: isolate_(isolate), code_(code) {}
const char* NameOfAddress(byte* pc) const override;
const char* NameInCode(byte* addr) const override;
const char* RootRelativeName(int offset) const override;
const CodeReference& code() const { return code_; }
private:
void InitExternalRefsCache() const;
Isolate* isolate_;
CodeReference code_;
EmbeddedVector<char, 128> v8_buffer_;
// Map from root-register relative offset of the external reference value to
// the external reference name (stored in the external reference table).
// This cache is used to recognize [root_reg + offs] patterns as direct
// access to certain external reference's value.
mutable std::unordered_map<int, const char*> directly_accessed_external_refs_;
};
void V8NameConverter::InitExternalRefsCache() const {
ExternalReferenceTable* external_reference_table =
isolate_->external_reference_table();
if (!external_reference_table->is_initialized()) return;
base::AddressRegion addressable_region =
isolate_->root_register_addressable_region();
Address isolate_root = isolate_->isolate_root();
for (uint32_t i = 0; i < ExternalReferenceTable::kSize; i++) {
Address address = external_reference_table->address(i);
if (addressable_region.contains(address)) {
int offset = static_cast<int>(address - isolate_root);
const char* name = external_reference_table->name(i);
directly_accessed_external_refs_.insert({offset, name});
}
}
}
const char* V8NameConverter::NameOfAddress(byte* pc) const {
if (!code_.is_null()) {
const char* name =
isolate_ ? isolate_->builtins()->Lookup(reinterpret_cast<Address>(pc))
: nullptr;
if (name != nullptr) {
SNPrintF(v8_buffer_, "%p (%s)", static_cast<void*>(pc), name);
return v8_buffer_.start();
}
int offs = static_cast<int>(reinterpret_cast<Address>(pc) -
code_.instruction_start());
// print as code offset, if it seems reasonable
if (0 <= offs && offs < code_.instruction_size()) {
SNPrintF(v8_buffer_, "%p <+0x%x>", static_cast<void*>(pc), offs);
return v8_buffer_.start();
}
wasm::WasmCode* wasm_code =
isolate_ ? isolate_->wasm_engine()->code_manager()->LookupCode(
reinterpret_cast<Address>(pc))
: nullptr;
if (wasm_code != nullptr) {
SNPrintF(v8_buffer_, "%p (%s)", static_cast<void*>(pc),
wasm::GetWasmCodeKindAsString(wasm_code->kind()));
return v8_buffer_.start();
}
}
return disasm::NameConverter::NameOfAddress(pc);
}
const char* V8NameConverter::NameInCode(byte* addr) const {
// The V8NameConverter is used for well known code, so we can "safely"
// dereference pointers in generated code.
return code_.is_null() ? "" : reinterpret_cast<const char*>(addr);
}
const char* V8NameConverter::RootRelativeName(int offset) const {
if (isolate_ == nullptr) return nullptr;
const int kRootsTableStart = IsolateData::roots_table_offset();
const unsigned kRootsTableSize = sizeof(RootsTable);
const int kExtRefsTableStart = IsolateData::external_reference_table_offset();
const unsigned kExtRefsTableSize = ExternalReferenceTable::kSizeInBytes;
const int kBuiltinsTableStart = IsolateData::builtins_table_offset();
const unsigned kBuiltinsTableSize =
Builtins::builtin_count * kSystemPointerSize;
if (static_cast<unsigned>(offset - kRootsTableStart) < kRootsTableSize) {
uint32_t offset_in_roots_table = offset - kRootsTableStart;
// Fail safe in the unlikely case of an arbitrary root-relative offset.
if (offset_in_roots_table % kSystemPointerSize != 0) return nullptr;
RootIndex root_index =
static_cast<RootIndex>(offset_in_roots_table / kSystemPointerSize);
SNPrintF(v8_buffer_, "root (%s)", RootsTable::name(root_index));
return v8_buffer_.start();
} else if (static_cast<unsigned>(offset - kExtRefsTableStart) <
kExtRefsTableSize) {
uint32_t offset_in_extref_table = offset - kExtRefsTableStart;
// Fail safe in the unlikely case of an arbitrary root-relative offset.
if (offset_in_extref_table % ExternalReferenceTable::kEntrySize != 0) {
return nullptr;
}
// Likewise if the external reference table is uninitialized.
if (!isolate_->external_reference_table()->is_initialized()) {
return nullptr;
}
SNPrintF(v8_buffer_, "external reference (%s)",
isolate_->external_reference_table()->NameFromOffset(
offset_in_extref_table));
return v8_buffer_.start();
} else if (static_cast<unsigned>(offset - kBuiltinsTableStart) <
kBuiltinsTableSize) {
uint32_t offset_in_builtins_table = (offset - kBuiltinsTableStart);
Builtins::Name builtin_id = static_cast<Builtins::Name>(
offset_in_builtins_table / kSystemPointerSize);
const char* name = Builtins::name(builtin_id);
SNPrintF(v8_buffer_, "builtin (%s)", name);
return v8_buffer_.start();
} else {
// It must be a direct access to one of the external values.
if (directly_accessed_external_refs_.empty()) {
InitExternalRefsCache();
}
auto iter = directly_accessed_external_refs_.find(offset);
if (iter != directly_accessed_external_refs_.end()) {
SNPrintF(v8_buffer_, "external value (%s)", iter->second);
return v8_buffer_.start();
}
return "WAAT??? What are we accessing here???";
}
}
static void DumpBuffer(std::ostream* os, StringBuilder* out) {
(*os) << out->Finalize() << std::endl;
out->Reset();
}
static const int kOutBufferSize = 2048 + String::kMaxShortPrintLength;
static const int kRelocInfoPosition = 57;
static void PrintRelocInfo(StringBuilder* out, Isolate* isolate,
const ExternalReferenceEncoder* ref_encoder,
std::ostream* os, CodeReference host,
RelocInfo* relocinfo, bool first_reloc_info = true) {
// Indent the printing of the reloc info.
if (first_reloc_info) {
// The first reloc info is printed after the disassembled instruction.
out->AddPadding(' ', kRelocInfoPosition - out->position());
} else {
// Additional reloc infos are printed on separate lines.
DumpBuffer(os, out);
out->AddPadding(' ', kRelocInfoPosition);
}
RelocInfo::Mode rmode = relocinfo->rmode();
if (rmode == RelocInfo::DEOPT_SCRIPT_OFFSET) {
out->AddFormatted(" ;; debug: deopt position, script offset '%d'",
static_cast<int>(relocinfo->data()));
} else if (rmode == RelocInfo::DEOPT_INLINING_ID) {
out->AddFormatted(" ;; debug: deopt position, inlining id '%d'",
static_cast<int>(relocinfo->data()));
} else if (rmode == RelocInfo::DEOPT_REASON) {
DeoptimizeReason reason = static_cast<DeoptimizeReason>(relocinfo->data());
out->AddFormatted(" ;; debug: deopt reason '%s'",
DeoptimizeReasonToString(reason));
} else if (rmode == RelocInfo::DEOPT_ID) {
out->AddFormatted(" ;; debug: deopt index %d",
static_cast<int>(relocinfo->data()));
} else if (rmode == RelocInfo::EMBEDDED_OBJECT) {
HeapStringAllocator allocator;
StringStream accumulator(&allocator);
relocinfo->target_object()->ShortPrint(&accumulator);
std::unique_ptr<char[]> obj_name = accumulator.ToCString();
out->AddFormatted(" ;; object: %s", obj_name.get());
} else if (rmode == RelocInfo::EXTERNAL_REFERENCE) {
const char* reference_name =
ref_encoder ? ref_encoder->NameOfAddress(
isolate, relocinfo->target_external_reference())
: "unknown";
out->AddFormatted(" ;; external reference (%s)", reference_name);
} else if (RelocInfo::IsCodeTargetMode(rmode)) {
out->AddFormatted(" ;; code:");
Code code = isolate->heap()->GcSafeFindCodeForInnerPointer(
relocinfo->target_address());
Code::Kind kind = code->kind();
if (code->is_builtin()) {
out->AddFormatted(" Builtin::%s", Builtins::name(code->builtin_index()));
} else {
out->AddFormatted(" %s", Code::Kind2String(kind));
}
} else if (RelocInfo::IsWasmStubCall(rmode) && host.is_wasm_code()) {
// Host is isolate-independent, try wasm native module instead.
wasm::WasmCode* code = host.as_wasm_code()->native_module()->Lookup(
relocinfo->wasm_stub_call_address());
out->AddFormatted(" ;; wasm stub: %s", code->GetRuntimeStubName());
} else if (RelocInfo::IsRuntimeEntry(rmode) && isolate &&
isolate->deoptimizer_data() != nullptr) {
// A runtime entry relocinfo might be a deoptimization bailout.
Address addr = relocinfo->target_address();
DeoptimizeKind type;
if (Deoptimizer::IsDeoptimizationEntry(isolate, addr, &type)) {
out->AddFormatted(" ;; %s deoptimization bailout",
Deoptimizer::MessageFor(type));
} else {
out->AddFormatted(" ;; %s", RelocInfo::RelocModeName(rmode));
}
} else {
out->AddFormatted(" ;; %s", RelocInfo::RelocModeName(rmode));
}
}
static int DecodeIt(Isolate* isolate, ExternalReferenceEncoder* ref_encoder,
std::ostream* os, CodeReference code,
const V8NameConverter& converter, byte* begin, byte* end,
Address current_pc) {
CHECK(!code.is_null());
v8::internal::EmbeddedVector<char, 128> decode_buffer;
v8::internal::EmbeddedVector<char, kOutBufferSize> out_buffer;
StringBuilder out(out_buffer.start(), out_buffer.length());
byte* pc = begin;
disasm::Disassembler d(converter,
disasm::Disassembler::kContinueOnUnimplementedOpcode);
RelocIterator* it = nullptr;
CodeCommentsIterator cit(code.code_comments());
// Relocation exists if we either have no isolate (wasm code),
// or we have an isolate and it is not an off-heap instruction stream.
if (!isolate ||
!InstructionStream::PcIsOffHeap(isolate, bit_cast<Address>(begin))) {
it = new RelocIterator(code);
} else {
// No relocation information when printing code stubs.
}
int constants = -1; // no constants being decoded at the start
while (pc < end) {
// First decode instruction so that we know its length.
byte* prev_pc = pc;
if (constants > 0) {
SNPrintF(decode_buffer,
"%08x constant",
*reinterpret_cast<int32_t*>(pc));
constants--;
pc += 4;
} else {
int num_const = d.ConstantPoolSizeAt(pc);
if (num_const >= 0) {
SNPrintF(decode_buffer,
"%08x constant pool begin (num_const = %d)",
*reinterpret_cast<int32_t*>(pc), num_const);
constants = num_const;
pc += 4;
} else if (it != nullptr && !it->done() &&
it->rinfo()->pc() == reinterpret_cast<Address>(pc) &&
it->rinfo()->rmode() == RelocInfo::INTERNAL_REFERENCE) {
// raw pointer embedded in code stream, e.g., jump table
byte* ptr = *reinterpret_cast<byte**>(pc);
SNPrintF(
decode_buffer, "%08" V8PRIxPTR " jump table entry %4" PRIuS,
reinterpret_cast<intptr_t>(ptr), static_cast<size_t>(ptr - begin));
pc += sizeof(ptr);
} else {
decode_buffer[0] = '\0';
pc += d.InstructionDecode(decode_buffer, pc);
}
}
// Collect RelocInfo for this instruction (prev_pc .. pc-1)
std::vector<const char*> comments;
std::vector<Address> pcs;
std::vector<RelocInfo::Mode> rmodes;
std::vector<intptr_t> datas;
if (it != nullptr) {
while (!it->done() && it->rinfo()->pc() < reinterpret_cast<Address>(pc)) {
// Collect all data.
pcs.push_back(it->rinfo()->pc());
rmodes.push_back(it->rinfo()->rmode());
datas.push_back(it->rinfo()->data());
it->next();
}
}
while (cit.HasCurrent() &&
cit.GetPCOffset() < static_cast<Address>(pc - begin)) {
comments.push_back(cit.GetComment());
cit.Next();
}
// Comments.
for (size_t i = 0; i < comments.size(); i++) {
out.AddFormatted(" %s", comments[i]);
DumpBuffer(os, &out);
}
// Instruction address and instruction offset.
if (FLAG_log_colour && reinterpret_cast<Address>(prev_pc) == current_pc) {
// If this is the given "current" pc, make it yellow and bold.
out.AddFormatted("\033[33;1m");
}
out.AddFormatted("%p %4" V8PRIxPTRDIFF " ", static_cast<void*>(prev_pc),
prev_pc - begin);
// Instruction.
out.AddFormatted("%s", decode_buffer.start());
// Print all the reloc info for this instruction which are not comments.
for (size_t i = 0; i < pcs.size(); i++) {
// Put together the reloc info
const CodeReference& host = code;
Address constant_pool =
host.is_null() ? kNullAddress : host.constant_pool();
RelocInfo relocinfo(pcs[i], rmodes[i], datas[i], Code(), constant_pool);
bool first_reloc_info = (i == 0);
PrintRelocInfo(&out, isolate, ref_encoder, os, code, &relocinfo,
first_reloc_info);
}
// If this is a constant pool load and we haven't found any RelocInfo
// already, check if we can find some RelocInfo for the target address in
// the constant pool.
if (pcs.empty() && !code.is_null()) {
RelocInfo dummy_rinfo(reinterpret_cast<Address>(prev_pc),
RelocInfo::NONE,
0, Code());
if (dummy_rinfo.IsInConstantPool()) {
Address constant_pool_entry_address =
dummy_rinfo.constant_pool_entry_address();
RelocIterator reloc_it(code);
while (!reloc_it.done()) {
if (reloc_it.rinfo()->IsInConstantPool() &&
(reloc_it.rinfo()->constant_pool_entry_address() ==
constant_pool_entry_address)) {
PrintRelocInfo(&out, isolate, ref_encoder, os, code,
reloc_it.rinfo());
break;
}
reloc_it.next();
}
}
}
if (FLAG_log_colour && reinterpret_cast<Address>(prev_pc) == current_pc) {
out.AddFormatted("\033[m");
}
DumpBuffer(os, &out);
}
// Emit comments following the last instruction (if any).
while (cit.HasCurrent() &&
cit.GetPCOffset() < static_cast<Address>(pc - begin)) {
out.AddFormatted(" %s", cit.GetComment());
DumpBuffer(os, &out);
cit.Next();
}
delete it;
return static_cast<int>(pc - begin);
}
int Disassembler::Decode(Isolate* isolate, std::ostream* os, byte* begin,
byte* end, CodeReference code, Address current_pc) {
V8NameConverter v8NameConverter(isolate, code);
if (isolate) {
// We have an isolate, so support external reference names.
SealHandleScope shs(isolate);
DisallowHeapAllocation no_alloc;
ExternalReferenceEncoder ref_encoder(isolate);
return DecodeIt(isolate, &ref_encoder, os, code, v8NameConverter, begin,
end, current_pc);
} else {
// No isolate => isolate-independent code. No external reference names.
return DecodeIt(nullptr, nullptr, os, code, v8NameConverter, begin, end,
current_pc);
}
}
#else // ENABLE_DISASSEMBLER
int Disassembler::Decode(Isolate* isolate, std::ostream* os, byte* begin,
byte* end, CodeReference code, Address current_pc) {
return 0;
}
#endif // ENABLE_DISASSEMBLER
} // namespace internal
} // namespace v8