code.cc

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// Copyright 2019 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/objects/code.h"
 
#include <iomanip>
 
#include "src/codegen/assembler-inl.h"
#include "src/codegen/flush-instruction-cache.h"
#include "src/codegen/reloc-info-inl.h"
#include "src/codegen/source-position-table.h"
#include "src/codegen/source-position.h"
#include "src/deoptimizer/deoptimizer.h"
#include "src/objects/code-inl.h"
 
#ifdef ENABLE_DISASSEMBLER
#include "src/diagnostics/disassembler.h"
#include "src/diagnostics/eh-frame.h"
#endif
 
namespace v8 {
namespace internal {
 
Tagged<Object> Code::raw_deoptimization_data_or_interpreter_data() const {
  return RawProtectedPointerField(kDeoptimizationDataOrInterpreterDataOffset)
      .load();
}
 
Tagged<Object> Code::raw_position_table() const {
  return RawProtectedPointerField(kPositionTableOffset).load();
}
 
void Code::ClearEmbeddedObjectsAndJSDispatchHandles(Heap* heap) {
  DisallowGarbageCollection no_gc;
  Tagged<HeapObject> undefined = ReadOnlyRoots(heap).undefined_value();
  Tagged<InstructionStream> istream = unchecked_instruction_stream();
  int mode_mask = RelocInfo::EmbeddedObjectModeMask();
#ifdef V8_ENABLE_LEAPTIERING
  mode_mask |= RelocInfo::JSDispatchHandleModeMask();
#endif
  {
    WritableJitAllocation jit_allocation = ThreadIsolation::LookupJitAllocation(
        istream->address(), istream->Size(),
        ThreadIsolation::JitAllocationType::kInstructionStream, true);
    for (WritableRelocIterator it(jit_allocation, istream, constant_pool(),
                                  mode_mask);
         !it.done(); it.next()) {
      const auto mode = it.rinfo()->rmode();
      if (RelocInfo::IsEmbeddedObjectMode(mode)) {
        it.rinfo()->set_target_object(istream, undefined, SKIP_WRITE_BARRIER);
#ifdef V8_ENABLE_LEAPTIERING
      } else {
        it.rinfo()->set_js_dispatch_handle(istream, kNullJSDispatchHandle,
                                           SKIP_WRITE_BARRIER);
#endif  // V8_ENABLE_LEAPTIERING
      }
    }
  }
  set_embedded_objects_cleared(true);
}
 
void Code::FlushICache() const {
  FlushInstructionCache(instruction_start(), instruction_size());
}
 
int Code::SourcePosition(int offset) const {
  CHECK_NE(kind(), CodeKind::BASELINE);
 
  // Subtract one because the current PC is one instruction after the call site.
  offset--;
 
  int position = 0;
  if (!has_source_position_table()) return position;
  for (SourcePositionTableIterator it(
           source_position_table(),
           SourcePositionTableIterator::kJavaScriptOnly,
           SourcePositionTableIterator::kDontSkipFunctionEntry);
       !it.done() && it.code_offset() <= offset; it.Advance()) {
    position = it.source_position().ScriptOffset();
  }
  return position;
}
 
int Code::SourceStatementPosition(int offset) const {
  CHECK_NE(kind(), CodeKind::BASELINE);
 
  // Subtract one because the current PC is one instruction after the call site.
  offset--;
 
  int position = 0;
  if (!has_source_position_table()) return position;
  for (SourcePositionTableIterator it(source_position_table());
       !it.done() && it.code_offset() <= offset; it.Advance()) {
    if (it.is_statement()) {
      position = it.source_position().ScriptOffset();
    }
  }
  return position;
}
 
SafepointEntry Code::GetSafepointEntry(Isolate* isolate, Address pc) {
  DCHECK(!is_maglevved());
  SafepointTable table(isolate, pc, *this);
  return table.FindEntry(pc);
}
 
MaglevSafepointEntry Code::GetMaglevSafepointEntry(Isolate* isolate,
                                                   Address pc) {
  DCHECK(is_maglevved());
  MaglevSafepointTable table(isolate, pc, *this);
  return table.FindEntry(pc);
}
 
bool Code::IsIsolateIndependent(Isolate* isolate) {
  static constexpr int kModeMask =
      RelocInfo::AllRealModesMask() &
      ~RelocInfo::ModeMask(RelocInfo::CONST_POOL) &
      ~RelocInfo::ModeMask(RelocInfo::OFF_HEAP_TARGET) &
      ~RelocInfo::ModeMask(RelocInfo::VENEER_POOL) &
      ~RelocInfo::ModeMask(RelocInfo::WASM_CANONICAL_SIG_ID) &
      ~RelocInfo::ModeMask(RelocInfo::WASM_CODE_POINTER_TABLE_ENTRY);
  static_assert(kModeMask ==
                (RelocInfo::ModeMask(RelocInfo::CODE_TARGET) |
                 RelocInfo::ModeMask(RelocInfo::RELATIVE_CODE_TARGET) |
                 RelocInfo::ModeMask(RelocInfo::COMPRESSED_EMBEDDED_OBJECT) |
                 RelocInfo::ModeMask(RelocInfo::FULL_EMBEDDED_OBJECT) |
                 RelocInfo::ModeMask(RelocInfo::EXTERNAL_REFERENCE) |
                 RelocInfo::ModeMask(RelocInfo::INTERNAL_REFERENCE) |
                 RelocInfo::ModeMask(RelocInfo::INTERNAL_REFERENCE_ENCODED) |
                 RelocInfo::ModeMask(RelocInfo::JS_DISPATCH_HANDLE) |
                 RelocInfo::ModeMask(RelocInfo::NEAR_BUILTIN_ENTRY) |
                 RelocInfo::ModeMask(RelocInfo::WASM_CALL) |
                 RelocInfo::ModeMask(RelocInfo::WASM_STUB_CALL)));
 
#if defined(V8_TARGET_ARCH_PPC64) || defined(V8_TARGET_ARCH_MIPS64)
  return RelocIterator(*this, kModeMask).done();
#elif defined(V8_TARGET_ARCH_X64) || defined(V8_TARGET_ARCH_ARM64) ||  \
    defined(V8_TARGET_ARCH_ARM) || defined(V8_TARGET_ARCH_S390X) ||    \
    defined(V8_TARGET_ARCH_IA32) || defined(V8_TARGET_ARCH_RISCV64) || \
    defined(V8_TARGET_ARCH_LOONG64) || defined(V8_TARGET_ARCH_RISCV32)
  for (RelocIterator it(*this, kModeMask); !it.done(); it.next()) {
    // On these platforms we emit relative builtin-to-builtin
    // jumps for isolate independent builtins in the snapshot. They are later
    // rewritten as pc-relative jumps to the off-heap instruction stream and are
    // thus process-independent. See also: FinalizeEmbeddedCodeTargets.
    if (RelocInfo::IsCodeTargetMode(it.rinfo()->rmode())) {
      Address target_address = it.rinfo()->target_address();
      if (OffHeapInstructionStream::PcIsOffHeap(isolate, target_address))
        continue;
 
      Tagged<Code> target = Code::FromTargetAddress(target_address);
      if (Builtins::IsIsolateIndependentBuiltin(target)) {
        continue;
      }
    }
    return false;
  }
  return true;
#else
#error Unsupported architecture.
#endif
}
 
bool Code::Inlines(Tagged<SharedFunctionInfo> sfi) {
  // We can only check for inlining for optimized code.
  DCHECK(is_optimized_code());
  DisallowGarbageCollection no_gc;
  Tagged<DeoptimizationData> const data =
      Cast<DeoptimizationData>(deoptimization_data());
  if (data->length() == 0) return false;
  if (data->GetSharedFunctionInfo() == sfi) return true;
  Tagged<DeoptimizationLiteralArray> const literals = data->LiteralArray();
  int const inlined_count = data->InlinedFunctionCount().value();
  for (int i = 0; i < inlined_count; ++i) {
    if (Cast<SharedFunctionInfo>(literals->get(i)) == sfi) return true;
  }
  return false;
}
 
#ifdef ENABLE_DISASSEMBLER
 
namespace {
 
void DisassembleCodeRange(Isolate* isolate, std::ostream& os, Tagged<Code> code,
                          Address begin, size_t size, Address current_pc,
                          size_t range_limit = 0) {
  Address end = begin + size;
  AllowHandleAllocation allow_handles;
  DisallowGarbageCollection no_gc;
  HandleScope handle_scope(isolate);
  Disassembler::Decode(isolate, os, reinterpret_cast<uint8_t*>(begin),
                       reinterpret_cast<uint8_t*>(end),
                       CodeReference(handle(code, isolate)), current_pc,
                       range_limit);
}
 
void DisassembleOnlyCode(const char* name, std::ostream& os, Isolate* isolate,
                         Tagged<Code> code, Address current_pc,
                         size_t range_limit) {
  int code_size = code->instruction_size();
  DisassembleCodeRange(isolate, os, code, code->instruction_start(), code_size,
                       current_pc, range_limit);
}
 
void Disassemble(const char* name, std::ostream& os, Isolate* isolate,
                 Tagged<Code> code, Address current_pc) {
  CodeKind kind = code->kind();
  os << "kind = " << CodeKindToString(kind) << "\n";
  if (name == nullptr && code->is_builtin()) {
    name = Builtins::name(code->builtin_id());
  }
  if ((name != nullptr) && (name[0] != '\0')) {
    os << "name = " << name << "\n";
  }
  os << "compiler = "
     << (code->is_turbofanned()       ? "turbofan"
         : code->is_maglevved()       ? "maglev"
         : kind == CodeKind::BASELINE ? "baseline"
                                      : "unknown")
     << "\n";
  os << "address = " << reinterpret_cast<void*>(code.ptr()) << "\n\n";
 
  {
    int code_size = code->instruction_size();
    os << "Instructions (size = " << code_size << ")\n";
    DisassembleCodeRange(isolate, os, code, code->instruction_start(),
                         code_size, current_pc);
 
    if (int pool_size = code->constant_pool_size()) {
      DCHECK_EQ(pool_size & kPointerAlignmentMask, 0);
      os << "\nConstant Pool (size = " << pool_size << ")\n";
      base::Vector<char> buf = base::Vector<char>::New(50);
      intptr_t* ptr = reinterpret_cast<intptr_t*>(code->constant_pool());
      for (int i = 0; i < pool_size; i += kSystemPointerSize, ptr++) {
        SNPrintF(buf, "%4d %08" V8PRIxPTR, i, *ptr);
        os << static_cast<const void*>(ptr) << "  " << buf.begin() << "\n";
      }
    }
  }
  os << "\n";
 
  // TODO(cbruni): add support for baseline code.
  if (code->has_source_position_table()) {
    {
      SourcePositionTableIterator it(
          code->source_position_table(),
          SourcePositionTableIterator::kJavaScriptOnly);
      if (!it.done()) {
        os << "Source positions:\n pc offset  position\n";
        for (; !it.done(); it.Advance()) {
          os << std::setw(10) << std::hex << it.code_offset() << std::dec
             << std::setw(10) << it.source_position().ScriptOffset()
             << (it.is_statement() ? "  statement" : "") << "\n";
        }
        os << "\n";
      }
    }
 
    {
      SourcePositionTableIterator it(
          code->source_position_table(),
          SourcePositionTableIterator::kExternalOnly);
      if (!it.done()) {
        os << "External Source positions:\n pc offset  fileid  line\n";
        for (; !it.done(); it.Advance()) {
          DCHECK(it.source_position().IsExternal());
          os << std::setw(10) << std::hex << it.code_offset() << std::dec
             << std::setw(10) << it.source_position().ExternalFileId()
             << std::setw(10) << it.source_position().ExternalLine() << "\n";
        }
        os << "\n";
      }
    }
  }
 
  if (code->uses_deoptimization_data()) {
    Tagged<DeoptimizationData> data =
        Cast<DeoptimizationData>(code->deoptimization_data());
    data->PrintDeoptimizationData(os);
  }
  os << "\n";
 
  if (code->uses_safepoint_table()) {
    if (code->is_maglevved()) {
      MaglevSafepointTable table(isolate, current_pc, code);
      table.Print(os);
    } else {
      SafepointTable table(isolate, current_pc, code);
      table.Print(os);
    }
    os << "\n";
  }
 
  if (code->has_handler_table()) {
    HandlerTable table(code);
    os << "Handler Table (size = " << table.NumberOfReturnEntries() << ")\n";
    if (CodeKindIsOptimizedJSFunction(kind)) {
      table.HandlerTableReturnPrint(os);
    }
    os << "\n";
  }
 
  os << "RelocInfo (size = " << code->relocation_size() << ")\n";
  if (code->has_instruction_stream()) {
    for (RelocIterator it(code); !it.done(); it.next()) {
      it.rinfo()->Print(isolate, os);
    }
  }
  os << "\n";
 
  if (code->has_unwinding_info()) {
    os << "UnwindingInfo (size = " << code->unwinding_info_size() << ")\n";
    EhFrameDisassembler eh_frame_disassembler(
        reinterpret_cast<uint8_t*>(code->unwinding_info_start()),
        reinterpret_cast<uint8_t*>(code->unwinding_info_end()));
    eh_frame_disassembler.DisassembleToStream(os);
    os << "\n";
  }
}
 
}  // namespace
 
void Code::Disassemble(const char* name, std::ostream& os, Isolate* isolate,
                       Address current_pc) {
  i::Disassemble(name, os, isolate, *this, current_pc);
}
 
void Code::DisassembleOnlyCode(const char* name, std::ostream& os,
                               Isolate* isolate, Address current_pc,
                               size_t range_limit) {
  i::DisassembleOnlyCode(name, os, isolate, *this, current_pc, range_limit);
}
 
#endif  // ENABLE_DISASSEMBLER
 
void Code::TraceMarkForDeoptimization(Isolate* isolate,
                                      LazyDeoptimizeReason reason) {
  Deoptimizer::TraceMarkForDeoptimization(isolate, *this, reason);
}
 
}  // namespace internal
}  // namespace v8