macro-assembler-base.cc

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// 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/codegen/macro-assembler-base.h"
 
#include "src/builtins/builtins.h"
#include "src/builtins/constants-table-builder.h"
#include "src/codegen/external-reference-encoder.h"
#include "src/common/globals.h"
#include "src/execution/isolate-data.h"
#include "src/execution/isolate-inl.h"
#include "src/snapshot/embedded/embedded-data-inl.h"
 
namespace v8 {
namespace internal {
 
MacroAssemblerBase::MacroAssemblerBase(Isolate* isolate,
                                       const AssemblerOptions& options,
                                       CodeObjectRequired create_code_object,
                                       std::unique_ptr<AssemblerBuffer> buffer)
    : MacroAssemblerBase(isolate, isolate->allocator(), options,
                         create_code_object, std::move(buffer)) {}
 
MacroAssemblerBase::MacroAssemblerBase(Isolate* isolate,
                                       MaybeAssemblerZone zone,
                                       AssemblerOptions options,
                                       CodeObjectRequired create_code_object,
                                       std::unique_ptr<AssemblerBuffer> buffer)
    : Assembler(zone, options, std::move(buffer)), isolate_(isolate) {
  if (create_code_object == CodeObjectRequired::kYes) {
    code_object_ = IndirectHandle<HeapObject>::New(
        ReadOnlyRoots(isolate).self_reference_marker(), isolate);
  }
}
 
Address MacroAssemblerBase::BuiltinEntry(Builtin builtin) {
  DCHECK(Builtins::IsBuiltinId(builtin));
  if (isolate_ != nullptr) {
    Address entry = isolate_->builtin_entry_table()[Builtins::ToInt(builtin)];
    DCHECK_EQ(entry,
              EmbeddedData::FromBlob(isolate_).InstructionStartOf(builtin));
    return entry;
  }
  EmbeddedData d = EmbeddedData::FromBlob();
  return d.InstructionStartOf(builtin);
}
 
void MacroAssemblerBase::IndirectLoadConstant(Register destination,
                                              Handle<HeapObject> object) {
  CHECK(root_array_available_);
 
  // Before falling back to the (fairly slow) lookup from the constants table,
  // check if any of the fast paths can be applied.
 
  Builtin builtin;
  RootIndex root_index;
  if (isolate()->roots_table().IsRootHandle(object, &root_index)) {
    // Roots are loaded relative to the root register.
    LoadRoot(destination, root_index);
  } else if (isolate()->builtins()->IsBuiltinHandle(object, &builtin)) {
    // Similar to roots, builtins may be loaded from the builtins table.
    LoadRootRelative(destination, RootRegisterOffsetForBuiltin(builtin));
  } else if (object.is_identical_to(code_object_) &&
             Builtins::IsBuiltinId(maybe_builtin_)) {
    // The self-reference loaded through Codevalue() may also be a builtin
    // and thus viable for a fast load.
    LoadRootRelative(destination, RootRegisterOffsetForBuiltin(maybe_builtin_));
  } else {
    CHECK(isolate()->IsGeneratingEmbeddedBuiltins());
    // Ensure the given object is in the builtins constants table and fetch its
    // index.
    BuiltinsConstantsTableBuilder* builder =
        isolate()->builtins_constants_table_builder();
    uint32_t index = builder->AddObject(object);
 
    // Slow load from the constants table.
    LoadFromConstantsTable(destination, index);
  }
}
 
void MacroAssemblerBase::IndirectLoadExternalReference(
    Register destination, ExternalReference reference) {
  CHECK(root_array_available_);
 
  if (IsAddressableThroughRootRegister(isolate(), reference)) {
    // Some external references can be efficiently loaded as an offset from
    // kRootRegister.
    intptr_t offset =
        RootRegisterOffsetForExternalReference(isolate(), reference);
    LoadRootRegisterOffset(destination, offset);
  } else {
    // Otherwise, do a memory load from the external reference table.
    LoadRootRelative(
        destination,
        RootRegisterOffsetForExternalReferenceTableEntry(isolate(), reference));
  }
}
 
// static
int32_t MacroAssemblerBase::RootRegisterOffsetForRootIndex(
    RootIndex root_index) {
  return IsolateData::root_slot_offset(root_index);
}
 
// static
int32_t MacroAssemblerBase::RootRegisterOffsetForBuiltin(Builtin builtin) {
  return IsolateData::BuiltinSlotOffset(builtin);
}
 
// static
intptr_t MacroAssemblerBase::RootRegisterOffsetForExternalReference(
    Isolate* isolate, const ExternalReference& reference) {
  if (reference.IsIsolateFieldId()) {
    return reference.offset_from_root_register();
  }
  return static_cast<intptr_t>(reference.address() - isolate->isolate_root());
}
 
// static
int32_t MacroAssemblerBase::RootRegisterOffsetForExternalReferenceTableEntry(
    Isolate* isolate, const ExternalReference& reference) {
  // Encode as an index into the external reference table stored on the
  // isolate.
  ExternalReferenceEncoder encoder(isolate);
  ExternalReferenceEncoder::Value v = encoder.Encode(reference.address());
  CHECK(!v.is_from_api());
 
  return IsolateData::external_reference_table_offset() +
         ExternalReferenceTable::OffsetOfEntry(v.index());
}
 
// static
bool MacroAssemblerBase::IsAddressableThroughRootRegister(
    Isolate* isolate, const ExternalReference& reference) {
  if (reference.IsIsolateFieldId()) return true;
 
  Address address = reference.address();
  return isolate->root_register_addressable_region().contains(address);
}
 
// static
Tagged_t MacroAssemblerBase::ReadOnlyRootPtr(RootIndex index,
                                             Isolate* isolate) {
  DCHECK(CanBeImmediate(index));
  Tagged<Object> obj = isolate->root(index);
  CHECK(IsHeapObject(obj));
  return V8HeapCompressionScheme::CompressObject(obj.ptr());
}
 
Tagged_t MacroAssemblerBase::ReadOnlyRootPtr(RootIndex index) {
  return ReadOnlyRootPtr(index, isolate_);
}
 
}  // namespace internal
}  // namespace v8