src/code-stubs.cc

// Copyright 2012 the V8 project authors. All rights reserved.
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// 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.
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//       with the distribution.
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//       contributors may be used to endorse or promote products derived
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//
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#include "v8.h"

#include "bootstrapper.h"
#include "code-stubs.h"
#include "stub-cache.h"
#include "factory.h"
#include "gdb-jit.h"
#include "macro-assembler.h"

namespace v8 {
namespace internal {

bool CodeStub::FindCodeInCache(Code** code_out) {
  Heap* heap = Isolate::Current()->heap();
  int index = heap->code_stubs()->FindEntry(GetKey());
  if (index != UnseededNumberDictionary::kNotFound) {
    *code_out = Code::cast(heap->code_stubs()->ValueAt(index));
    return true;
  }
  return false;
}


void CodeStub::GenerateCode(MacroAssembler* masm) {
  // Update the static counter each time a new code stub is generated.
  masm->isolate()->counters()->code_stubs()->Increment();

  // Nested stubs are not allowed for leaves.
  AllowStubCallsScope allow_scope(masm, false);

  // Generate the code for the stub.
  masm->set_generating_stub(true);
  NoCurrentFrameScope scope(masm);
  Generate(masm);
}


SmartArrayPointer<const char> CodeStub::GetName() {
  char buffer[100];
  NoAllocationStringAllocator allocator(buffer,
                                        static_cast<unsigned>(sizeof(buffer)));
  StringStream stream(&allocator);
  PrintName(&stream);
  return stream.ToCString();
}


void CodeStub::RecordCodeGeneration(Code* code, MacroAssembler* masm) {
  code->set_major_key(MajorKey());

  Isolate* isolate = masm->isolate();
  SmartArrayPointer<const char> name = GetName();
  PROFILE(isolate, CodeCreateEvent(Logger::STUB_TAG, code, *name));
  GDBJIT(AddCode(GDBJITInterface::STUB, *name, code));
  Counters* counters = isolate->counters();
  counters->total_stubs_code_size()->Increment(code->instruction_size());

#ifdef ENABLE_DISASSEMBLER
  if (FLAG_print_code_stubs) {
    code->Disassemble(*name);
    PrintF("\n");
  }
#endif
}


int CodeStub::GetCodeKind() {
  return Code::STUB;
}


Handle<Code> CodeStub::GetCode() {
  Isolate* isolate = Isolate::Current();
  Factory* factory = isolate->factory();
  Heap* heap = isolate->heap();
  Code* code;
  if (UseSpecialCache()
      ? FindCodeInSpecialCache(&code)
      : FindCodeInCache(&code)) {
    ASSERT(IsPregenerated() == code->is_pregenerated());
    return Handle<Code>(code);
  }

  {
    HandleScope scope(isolate);

    // Generate the new code.
    MacroAssembler masm(isolate, NULL, 256);
    GenerateCode(&masm);

    // Create the code object.
    CodeDesc desc;
    masm.GetCode(&desc);

    // Copy the generated code into a heap object.
    Code::Flags flags = Code::ComputeFlags(
        static_cast<Code::Kind>(GetCodeKind()),
        GetICState());
    Handle<Code> new_object = factory->NewCode(
        desc, flags, masm.CodeObject(), NeedsImmovableCode());
    RecordCodeGeneration(*new_object, &masm);
    FinishCode(new_object);

    if (UseSpecialCache()) {
      AddToSpecialCache(new_object);
    } else {
      // Update the dictionary and the root in Heap.
      Handle<UnseededNumberDictionary> dict =
          factory->DictionaryAtNumberPut(
              Handle<UnseededNumberDictionary>(heap->code_stubs()),
              GetKey(),
              new_object);
      heap->public_set_code_stubs(*dict);
    }
    code = *new_object;
  }

  Activate(code);
  ASSERT(!NeedsImmovableCode() || heap->lo_space()->Contains(code));
  return Handle<Code>(code, isolate);
}


const char* CodeStub::MajorName(CodeStub::Major major_key,
                                bool allow_unknown_keys) {
  switch (major_key) {
#define DEF_CASE(name) case name: return #name "Stub";
    CODE_STUB_LIST(DEF_CASE)
#undef DEF_CASE
    default:
      if (!allow_unknown_keys) {
        UNREACHABLE();
      }
      return NULL;
  }
}


void CodeStub::PrintName(StringStream* stream) {
  stream->Add("%s", MajorName(MajorKey(), false));
}


void ICCompareStub::AddToSpecialCache(Handle<Code> new_object) {
  ASSERT(*known_map_ != NULL);
  Isolate* isolate = new_object->GetIsolate();
  Factory* factory = isolate->factory();
  return Map::UpdateCodeCache(known_map_,
                              factory->compare_ic_symbol(),
                              new_object);
}


bool ICCompareStub::FindCodeInSpecialCache(Code** code_out) {
  Isolate* isolate = known_map_->GetIsolate();
  Factory* factory = isolate->factory();
  Code::Flags flags = Code::ComputeFlags(
      static_cast<Code::Kind>(GetCodeKind()),
      UNINITIALIZED);
  Handle<Object> probe(
      known_map_->FindInCodeCache(*factory->compare_ic_symbol(), flags));
  if (probe->IsCode()) {
    *code_out = Code::cast(*probe);
    return true;
  }
  return false;
}


int ICCompareStub::MinorKey() {
  return OpField::encode(op_ - Token::EQ) | StateField::encode(state_);
}


void ICCompareStub::Generate(MacroAssembler* masm) {
  switch (state_) {
    case CompareIC::UNINITIALIZED:
      GenerateMiss(masm);
      break;
    case CompareIC::SMIS:
      GenerateSmis(masm);
      break;
    case CompareIC::HEAP_NUMBERS:
      GenerateHeapNumbers(masm);
      break;
    case CompareIC::STRINGS:
      GenerateStrings(masm);
      break;
    case CompareIC::SYMBOLS:
      GenerateSymbols(masm);
      break;
    case CompareIC::OBJECTS:
      GenerateObjects(masm);
      break;
    case CompareIC::KNOWN_OBJECTS:
      ASSERT(*known_map_ != NULL);
      GenerateKnownObjects(masm);
      break;
    default:
      UNREACHABLE();
  }
}


void InstanceofStub::PrintName(StringStream* stream) {
  const char* args = "";
  if (HasArgsInRegisters()) {
    args = "_REGS";
  }

  const char* inline_check = "";
  if (HasCallSiteInlineCheck()) {
    inline_check = "_INLINE";
  }

  const char* return_true_false_object = "";
  if (ReturnTrueFalseObject()) {
    return_true_false_object = "_TRUEFALSE";
  }

  stream->Add("InstanceofStub%s%s%s",
              args,
              inline_check,
              return_true_false_object);
}


void JSEntryStub::FinishCode(Handle<Code> code) {
  Handle<FixedArray> handler_table =
      code->GetIsolate()->factory()->NewFixedArray(1, TENURED);
  handler_table->set(0, Smi::FromInt(handler_offset_));
  code->set_handler_table(*handler_table);
}


void KeyedLoadElementStub::Generate(MacroAssembler* masm) {
  switch (elements_kind_) {
    case FAST_ELEMENTS:
    case FAST_SMI_ONLY_ELEMENTS:
      KeyedLoadStubCompiler::GenerateLoadFastElement(masm);
      break;
    case FAST_DOUBLE_ELEMENTS:
      KeyedLoadStubCompiler::GenerateLoadFastDoubleElement(masm);
      break;
    case EXTERNAL_BYTE_ELEMENTS:
    case EXTERNAL_UNSIGNED_BYTE_ELEMENTS:
    case EXTERNAL_SHORT_ELEMENTS:
    case EXTERNAL_UNSIGNED_SHORT_ELEMENTS:
    case EXTERNAL_INT_ELEMENTS:
    case EXTERNAL_UNSIGNED_INT_ELEMENTS:
    case EXTERNAL_FLOAT_ELEMENTS:
    case EXTERNAL_DOUBLE_ELEMENTS:
    case EXTERNAL_PIXEL_ELEMENTS:
      KeyedLoadStubCompiler::GenerateLoadExternalArray(masm, elements_kind_);
      break;
    case DICTIONARY_ELEMENTS:
      KeyedLoadStubCompiler::GenerateLoadDictionaryElement(masm);
      break;
    case NON_STRICT_ARGUMENTS_ELEMENTS:
      UNREACHABLE();
      break;
  }
}


void KeyedStoreElementStub::Generate(MacroAssembler* masm) {
  switch (elements_kind_) {
    case FAST_ELEMENTS:
    case FAST_SMI_ONLY_ELEMENTS: {
      KeyedStoreStubCompiler::GenerateStoreFastElement(masm,
                                                       is_js_array_,
                                                       elements_kind_,
                                                       grow_mode_);
    }
      break;
    case FAST_DOUBLE_ELEMENTS:
      KeyedStoreStubCompiler::GenerateStoreFastDoubleElement(masm,
                                                             is_js_array_,
                                                             grow_mode_);
      break;
    case EXTERNAL_BYTE_ELEMENTS:
    case EXTERNAL_UNSIGNED_BYTE_ELEMENTS:
    case EXTERNAL_SHORT_ELEMENTS:
    case EXTERNAL_UNSIGNED_SHORT_ELEMENTS:
    case EXTERNAL_INT_ELEMENTS:
    case EXTERNAL_UNSIGNED_INT_ELEMENTS:
    case EXTERNAL_FLOAT_ELEMENTS:
    case EXTERNAL_DOUBLE_ELEMENTS:
    case EXTERNAL_PIXEL_ELEMENTS:
      KeyedStoreStubCompiler::GenerateStoreExternalArray(masm, elements_kind_);
      break;
    case DICTIONARY_ELEMENTS:
      KeyedStoreStubCompiler::GenerateStoreDictionaryElement(masm);
      break;
    case NON_STRICT_ARGUMENTS_ELEMENTS:
      UNREACHABLE();
      break;
  }
}


void ArgumentsAccessStub::PrintName(StringStream* stream) {
  stream->Add("ArgumentsAccessStub_");
  switch (type_) {
    case READ_ELEMENT: stream->Add("ReadElement"); break;
    case NEW_NON_STRICT_FAST: stream->Add("NewNonStrictFast"); break;
    case NEW_NON_STRICT_SLOW: stream->Add("NewNonStrictSlow"); break;
    case NEW_STRICT: stream->Add("NewStrict"); break;
  }
}


void CallFunctionStub::PrintName(StringStream* stream) {
  stream->Add("CallFunctionStub_Args%d", argc_);
  if (ReceiverMightBeImplicit()) stream->Add("_Implicit");
  if (RecordCallTarget()) stream->Add("_Recording");
}


void CallConstructStub::PrintName(StringStream* stream) {
  stream->Add("CallConstructStub");
  if (RecordCallTarget()) stream->Add("_Recording");
}


void ToBooleanStub::PrintName(StringStream* stream) {
  stream->Add("ToBooleanStub_");
  types_.Print(stream);
}


void ToBooleanStub::Types::Print(StringStream* stream) const {
  if (IsEmpty()) stream->Add("None");
  if (Contains(UNDEFINED)) stream->Add("Undefined");
  if (Contains(BOOLEAN)) stream->Add("Bool");
  if (Contains(NULL_TYPE)) stream->Add("Null");
  if (Contains(SMI)) stream->Add("Smi");
  if (Contains(SPEC_OBJECT)) stream->Add("SpecObject");
  if (Contains(STRING)) stream->Add("String");
  if (Contains(HEAP_NUMBER)) stream->Add("HeapNumber");
}


void ToBooleanStub::Types::TraceTransition(Types to) const {
  if (!FLAG_trace_ic) return;
  char buffer[100];
  NoAllocationStringAllocator allocator(buffer,
                                        static_cast<unsigned>(sizeof(buffer)));
  StringStream stream(&allocator);
  stream.Add("[ToBooleanIC (");
  Print(&stream);
  stream.Add("->");
  to.Print(&stream);
  stream.Add(")]\n");
  stream.OutputToStdOut();
}


bool ToBooleanStub::Types::Record(Handle<Object> object) {
  if (object->IsUndefined()) {
    Add(UNDEFINED);
    return false;
  } else if (object->IsBoolean()) {
    Add(BOOLEAN);
    return object->IsTrue();
  } else if (object->IsNull()) {
    Add(NULL_TYPE);
    return false;
  } else if (object->IsSmi()) {
    Add(SMI);
    return Smi::cast(*object)->value() != 0;
  } else if (object->IsSpecObject()) {
    Add(SPEC_OBJECT);
    return !object->IsUndetectableObject();
  } else if (object->IsString()) {
    Add(STRING);
    return !object->IsUndetectableObject() &&
        String::cast(*object)->length() != 0;
  } else if (object->IsHeapNumber()) {
    ASSERT(!object->IsUndetectableObject());
    Add(HEAP_NUMBER);
    double value = HeapNumber::cast(*object)->value();
    return value != 0 && !isnan(value);
  } else {
    // We should never see an internal object at runtime here!
    UNREACHABLE();
    return true;
  }
}


bool ToBooleanStub::Types::NeedsMap() const {
  return Contains(ToBooleanStub::SPEC_OBJECT)
      || Contains(ToBooleanStub::STRING)
      || Contains(ToBooleanStub::HEAP_NUMBER);
}


bool ToBooleanStub::Types::CanBeUndetectable() const {
  return Contains(ToBooleanStub::SPEC_OBJECT)
      || Contains(ToBooleanStub::STRING);
}


void ElementsTransitionAndStoreStub::Generate(MacroAssembler* masm) {
  Label fail;
  if (!FLAG_trace_elements_transitions) {
    if (to_ == FAST_ELEMENTS) {
      if (from_ == FAST_SMI_ONLY_ELEMENTS) {
        ElementsTransitionGenerator::GenerateSmiOnlyToObject(masm);
      } else if (from_ == FAST_DOUBLE_ELEMENTS) {
        ElementsTransitionGenerator::GenerateDoubleToObject(masm, &fail);
      } else {
        UNREACHABLE();
      }
      KeyedStoreStubCompiler::GenerateStoreFastElement(masm,
                                                       is_jsarray_,
                                                       FAST_ELEMENTS,
                                                       grow_mode_);
    } else if (from_ == FAST_SMI_ONLY_ELEMENTS && to_ == FAST_DOUBLE_ELEMENTS) {
      ElementsTransitionGenerator::GenerateSmiOnlyToDouble(masm, &fail);
      KeyedStoreStubCompiler::GenerateStoreFastDoubleElement(masm,
                                                             is_jsarray_,
                                                             grow_mode_);
    } else {
      UNREACHABLE();
    }
  }
  masm->bind(&fail);
  KeyedStoreIC::GenerateRuntimeSetProperty(masm, strict_mode_);
}

} }  // namespace v8::internal