v8/src/lithium-codegen.cc

// Copyright 2013 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * 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.
//     * Neither the name of Google Inc. nor the names of its
//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
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#include "v8.h"

#include "lithium-codegen.h"

#if V8_TARGET_ARCH_IA32
#include "ia32/lithium-ia32.h"
#include "ia32/lithium-codegen-ia32.h"
#elif V8_TARGET_ARCH_X64
#include "x64/lithium-x64.h"
#include "x64/lithium-codegen-x64.h"
#elif V8_TARGET_ARCH_ARM
#include "arm/lithium-arm.h"
#include "arm/lithium-codegen-arm.h"
#elif V8_TARGET_ARCH_ARM64
#include "arm64/lithium-arm64.h"
#include "arm64/lithium-codegen-arm64.h"
#elif V8_TARGET_ARCH_MIPS
#include "mips/lithium-mips.h"
#include "mips/lithium-codegen-mips.h"
#else
#error Unsupported target architecture.
#endif

namespace v8 {
namespace internal {


HGraph* LCodeGenBase::graph() const {
  return chunk()->graph();
}


LCodeGenBase::LCodeGenBase(LChunk* chunk,
                           MacroAssembler* assembler,
                           CompilationInfo* info)
    : chunk_(static_cast<LPlatformChunk*>(chunk)),
      masm_(assembler),
      info_(info),
      zone_(info->zone()),
      status_(UNUSED),
      current_block_(-1),
      current_instruction_(-1),
      instructions_(chunk->instructions()),
      last_lazy_deopt_pc_(0) {
}


bool LCodeGenBase::GenerateBody() {
  ASSERT(is_generating());
  bool emit_instructions = true;
  LCodeGen* codegen = static_cast<LCodeGen*>(this);
  for (current_instruction_ = 0;
       !is_aborted() && current_instruction_ < instructions_->length();
       current_instruction_++) {
    LInstruction* instr = instructions_->at(current_instruction_);

    // Don't emit code for basic blocks with a replacement.
    if (instr->IsLabel()) {
      emit_instructions = !LLabel::cast(instr)->HasReplacement() &&
          (!FLAG_unreachable_code_elimination ||
           instr->hydrogen_value()->block()->IsReachable());
      if (FLAG_code_comments && !emit_instructions) {
        Comment(
            ";;; <@%d,#%d> -------------------- B%d (unreachable/replaced) "
            "--------------------",
            current_instruction_,
            instr->hydrogen_value()->id(),
            instr->hydrogen_value()->block()->block_id());
      }
    }
    if (!emit_instructions) continue;

    if (FLAG_code_comments && instr->HasInterestingComment(codegen)) {
      Comment(";;; <@%d,#%d> %s",
              current_instruction_,
              instr->hydrogen_value()->id(),
              instr->Mnemonic());
    }

    GenerateBodyInstructionPre(instr);

    HValue* value = instr->hydrogen_value();
    if (!value->position().IsUnknown()) {
      RecordAndWritePosition(
        chunk()->graph()->SourcePositionToScriptPosition(value->position()));
    }

    instr->CompileToNative(codegen);

    GenerateBodyInstructionPost(instr);
  }
  EnsureSpaceForLazyDeopt(Deoptimizer::patch_size());
  last_lazy_deopt_pc_ = masm()->pc_offset();
  return !is_aborted();
}


void LCodeGenBase::CheckEnvironmentUsage() {
#ifdef DEBUG
  bool dead_block = false;
  for (int i = 0; i < instructions_->length(); i++) {
    LInstruction* instr = instructions_->at(i);
    HValue* hval = instr->hydrogen_value();
    if (instr->IsLabel()) dead_block = LLabel::cast(instr)->HasReplacement();
    if (dead_block || !hval->block()->IsReachable()) continue;

    HInstruction* hinstr = HInstruction::cast(hval);
    if (!hinstr->CanDeoptimize() && instr->HasEnvironment()) {
      V8_Fatal(__FILE__, __LINE__, "CanDeoptimize is wrong for %s (%s)\n",
               hinstr->Mnemonic(), instr->Mnemonic());
    }

    if (instr->HasEnvironment() && !instr->environment()->has_been_used()) {
      V8_Fatal(__FILE__, __LINE__, "unused environment for %s (%s)\n",
               hinstr->Mnemonic(), instr->Mnemonic());
    }
  }
#endif
}


void LCodeGenBase::Comment(const char* format, ...) {
  if (!FLAG_code_comments) return;
  char buffer[4 * KB];
  StringBuilder builder(buffer, ARRAY_SIZE(buffer));
  va_list arguments;
  va_start(arguments, format);
  builder.AddFormattedList(format, arguments);
  va_end(arguments);

  // Copy the string before recording it in the assembler to avoid
  // issues when the stack allocated buffer goes out of scope.
  size_t length = builder.position();
  Vector<char> copy = Vector<char>::New(static_cast<int>(length) + 1);
  OS::MemCopy(copy.start(), builder.Finalize(), copy.length());
  masm()->RecordComment(copy.start());
}


int LCodeGenBase::GetNextEmittedBlock() const {
  for (int i = current_block_ + 1; i < graph()->blocks()->length(); ++i) {
    if (!graph()->blocks()->at(i)->IsReachable()) continue;
    if (!chunk_->GetLabel(i)->HasReplacement()) return i;
  }
  return -1;
}


static void AddWeakObjectToCodeDependency(Isolate* isolate,
                                          Handle<Object> object,
                                          Handle<Code> code) {
  Heap* heap = isolate->heap();
  heap->EnsureWeakObjectToCodeTable();
  Handle<DependentCode> dep(heap->LookupWeakObjectToCodeDependency(*object));
  dep = DependentCode::Insert(dep, DependentCode::kWeakCodeGroup, code);
  heap->AddWeakObjectToCodeDependency(object, dep);
}


void LCodeGenBase::RegisterWeakObjectsInOptimizedCode(Handle<Code> code) {
  ASSERT(code->is_optimized_code());
  ZoneList<Handle<Map> > maps(1, zone());
  ZoneList<Handle<JSObject> > objects(1, zone());
  ZoneList<Handle<Cell> > cells(1, zone());
  int mode_mask = RelocInfo::ModeMask(RelocInfo::EMBEDDED_OBJECT) |
                  RelocInfo::ModeMask(RelocInfo::CELL);
  for (RelocIterator it(*code, mode_mask); !it.done(); it.next()) {
    RelocInfo::Mode mode = it.rinfo()->rmode();
    if (mode == RelocInfo::CELL &&
        code->IsWeakObjectInOptimizedCode(it.rinfo()->target_cell())) {
      Handle<Cell> cell(it.rinfo()->target_cell());
      cells.Add(cell, zone());
    } else if (mode == RelocInfo::EMBEDDED_OBJECT &&
               code->IsWeakObjectInOptimizedCode(it.rinfo()->target_object())) {
      if (it.rinfo()->target_object()->IsMap()) {
        Handle<Map> map(Map::cast(it.rinfo()->target_object()));
        maps.Add(map, zone());
      } else if (it.rinfo()->target_object()->IsJSObject()) {
        Handle<JSObject> object(JSObject::cast(it.rinfo()->target_object()));
        objects.Add(object, zone());
      } else if (it.rinfo()->target_object()->IsCell()) {
        Handle<Cell> cell(Cell::cast(it.rinfo()->target_object()));
        cells.Add(cell, zone());
      }
    }
  }
  if (FLAG_enable_ool_constant_pool) {
    code->constant_pool()->set_weak_object_state(
        ConstantPoolArray::WEAK_OBJECTS_IN_OPTIMIZED_CODE);
  }
#ifdef VERIFY_HEAP
  // This disables verification of weak embedded objects after full GC.
  // AddDependentCode can cause a GC, which would observe the state where
  // this code is not yet in the depended code lists of the embedded maps.
  NoWeakObjectVerificationScope disable_verification_of_embedded_objects;
#endif
  for (int i = 0; i < maps.length(); i++) {
    Map::AddDependentCode(maps.at(i), DependentCode::kWeakCodeGroup, code);
  }
  for (int i = 0; i < objects.length(); i++) {
    AddWeakObjectToCodeDependency(isolate(), objects.at(i), code);
  }
  for (int i = 0; i < cells.length(); i++) {
    AddWeakObjectToCodeDependency(isolate(), cells.at(i), code);
  }
}


} }  // namespace v8::internal