Implement Fast Accessor Builder

src/compiler/fast-accessor-assembler.cc

+// Copyright 2015 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/compiler/fast-accessor-assembler.h"
+
+#include "src/base/logging.h"
+#include "src/compiler/graph.h"
+#include "src/compiler/linkage.h"
+#include "src/compiler/pipeline.h"
+#include "src/compiler/raw-machine-assembler.h"
+#include "src/compiler/schedule.h"
+#include "src/compiler/verifier.h"
+#include "src/handles-inl.h"
+#include "src/objects.h"  // For FAA::GetInternalField impl.
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+FastAccessorAssembler::FastAccessorAssembler(Isolate* isolate)
+    : zone_(),
+      assembler_(new RawMachineAssembler(
+          isolate, new (zone()) Graph(zone()),
+          Linkage::GetJSCallDescriptor(&zone_, false, 1,
+                                       CallDescriptor::kNoFlags))),
+      state_(kBuilding) {}
+
+
+FastAccessorAssembler::~FastAccessorAssembler() {}
+
+
+FastAccessorAssembler::ValueId FastAccessorAssembler::IntegerConstant(
+    int const_value) {
+  CHECK_EQ(kBuilding, state_);
+  return FromRaw(assembler_->NumberConstant(const_value));
+}
+
+
+FastAccessorAssembler::ValueId FastAccessorAssembler::GetCallTarget() {
+  CHECK_EQ(kBuilding, state_);
+
+  // For JS call descriptor, we can assume that the call target / 'this' pointer

[Michael Starzinger, 2015/12/02 19:28:06]

We need to use internal nomenclature here, otherwise all V8 devs will be highly
confused.

1) "call target" -> Parameter(-1), refers to the closure (i.e. JSFunction
object) that represents the target function of the call and that this code
object has been attached to.

2) "receiver" (aka "this") -> Parameter(0), refers to the object acting as the
message receiver for the method invocation. Implicitly that is the first
parameter to the function, all other arguments have been shifted back by one.

Actionable feedback: The comment should only talk about "receiver" or "this" and
I would rename the function to GetReceiver() or something similar.

[vogelheim, 2015/12/03 13:10:31]

Done.

+  // is parameter 0. If we use other call descriptors, this may or may not hold.
+  // So let's check.
+  CHECK(assembler_->call_descriptor()->IsJSFunctionCall());
+  return FromRaw(assembler_->Parameter(0));
+}
+
+
+FastAccessorAssembler::ValueId FastAccessorAssembler::GetInternalField(

[Michael Starzinger, 2015/12/02 19:28:06]

nit: How would you feel about s/GetInternalField/LoadInternalField/ here?

[vogelheim, 2015/12/03 13:10:31]

Done.

+    ValueId value, int field_no) {
+  CHECK_EQ(kBuilding, state_);
+  return FromRaw(assembler_->Load(
+      kMachPtr, FromId(value),
+      assembler_->IntPtrConstant(JSObject::kHeaderSize - kHeapObjectTag +

[Michael Starzinger, 2015/12/02 19:28:06]

This calculation is only correct for JSObject, for several subclasses of
JSObject which can also have internal fields the header size differs (i.e. see
JSObject::GetHeaderSize). If we want to go with this restriction, then it needs
to be clearly documented.

[vogelheim, 2015/12/03 13:10:31]

Changed to check for JSObject, and to return Undefined if it doesn't match. I'm
not sure that's the best way: Alternatively, the function could take a Label
parameter so that the user can implement their own check-fail branch.

+                                 kPointerSize * field_no)));
+}
+
+
+FastAccessorAssembler::ValueId FastAccessorAssembler::LoadValue(
+    FastAccessorAssembler::ValueId value, int offset) {
+  CHECK_EQ(kBuilding, state_);
+  return FromRaw(assembler_->Load(kMachIntPtr, FromId(value),
+                                  assembler_->IntPtrConstant(offset)));
+}
+
+
+FastAccessorAssembler::ValueId FastAccessorAssembler::LoadObject(
+    FastAccessorAssembler::ValueId value, int offset) {
+  CHECK_EQ(kBuilding, state_);
+  return FromRaw(assembler_->Load(
+      kMachAnyTagged, assembler_->Load(kMachPtr, FromId(value),
+                                       assembler_->IntPtrConstant(offset))));
+}
+
+
+void FastAccessorAssembler::ReturnValue(ValueId value) {
+  CHECK_EQ(kBuilding, state_);
+  assembler_->Return(FromId(value));
+}
+
+
+void FastAccessorAssembler::CheckFlagSetOrReturnNull(
+    FastAccessorAssembler::ValueId value, int mask) {
+  CHECK_EQ(kBuilding, state_);
+  RawMachineLabel pass, fail;
+  assembler_->Branch(
+      assembler_->Word32Equal(
+          assembler_->Word32And(FromId(value), assembler_->Int32Constant(mask)),
+          assembler_->Int32Constant(0)),
+      &pass, &fail);
+  assembler_->Bind(&fail);
+  assembler_->Return(assembler_->NullConstant());
+  assembler_->Bind(&pass);
+}
+
+
+void FastAccessorAssembler::CheckNotNullOrReturnNull(ValueId value) {

[Michael Starzinger, 2015/12/02 19:28:06]

One "null" is more "null" than the other "null" ...
s/CheckNotNullOrReturnNull/CheckNotZeroOrReturnNull/

[vogelheim, 2015/12/03 13:10:31]

Done.

+  CHECK_EQ(kBuilding, state_);
+  RawMachineLabel is_null, not_null;
+  assembler_->Branch(
+      assembler_->IntPtrEqual(FromId(value), assembler_->IntPtrConstant(0)),
+      &is_null, &not_null);
+  assembler_->Bind(&is_null);
+  assembler_->Return(assembler_->NullConstant());
+  assembler_->Bind(&not_null);
+}
+
+
+FastAccessorAssembler::LabelId FastAccessorAssembler::MakeLabel() {
+  CHECK_EQ(kBuilding, state_);
+  RawMachineLabel* label = new RawMachineLabel;

[Michael Starzinger, 2015/12/02 19:28:06]

Can we allocate the Labels in our Zone please? Otherwise they will leak if the
Build() method below is never called.

[vogelheim, 2015/12/03 13:10:31]

Done.

+  return FromRaw(label);
+}
+
+
+void FastAccessorAssembler::SetLabel(LabelId label_id) {
+  CHECK_EQ(kBuilding, state_);
+  assembler_->Bind(FromId(label_id));
+}
+
+
+void FastAccessorAssembler::CheckNotNullOrJump(ValueId value_id,

[Michael Starzinger, 2015/12/02 19:28:06]

Likewise s/CheckNotNullOrJump/CheckNotZeroOrJump/

[vogelheim, 2015/12/03 13:10:31]

Done.

+                                               LabelId label_id) {
+  CHECK_EQ(kBuilding, state_);
+  RawMachineLabel pass;
+  assembler_->Branch(
+      assembler_->IntPtrEqual(FromId(value_id), assembler_->IntPtrConstant(0)),
+      &pass, FromId(label_id));
+  assembler_->Bind(&pass);
+}
+
+
+MaybeHandle<Code> FastAccessorAssembler::Build() {
+  CHECK_EQ(kBuilding, state_);
+
+  // Cleanup: We no longer need this.
+  nodes_.clear();
+  for (auto label : labels_) {
+    delete label;

[Michael Starzinger, 2015/12/02 19:28:06]

See comment above, please allocate in Zone and don't delete here.

[vogelheim, 2015/12/03 13:10:31]

Done.

+  }
+  labels_.clear();
+
+  // Export the schedule and call the compiler.
+  CompilationInfo info("FastAccessorAssembler", assembler_->isolate(), zone());
+  Schedule* schedule = assembler_->Export();
+  MaybeHandle<Code> code = Pipeline::GenerateCodeForTesting(

[Michael Starzinger, 2015/12/02 19:28:06]

This definitely needs a big fat TODO that we should add a separate (non-testing)
entry point into the Pipeline for this.

[vogelheim, 2015/12/03 13:10:31]

Done.

+      &info, assembler_->call_descriptor(), assembler_->graph(), schedule);
+
+  // Update state & return.
+  state_ = !code.is_null() ? kBuilt : kError;
+  return code;
+}
+
+
+FastAccessorAssembler::ValueId FastAccessorAssembler::FromRaw(Node* node) {
+  nodes_.push_back(node);
+  ValueId value = {nodes_.size() - 1};
+  return value;
+}
+
+
+FastAccessorAssembler::LabelId FastAccessorAssembler::FromRaw(
+    RawMachineLabel* label) {
+  labels_.push_back(label);
+  LabelId label_id = {labels_.size() - 1};
+  return label_id;
+}
+
+
+Node* FastAccessorAssembler::FromId(
+    FastAccessorAssembler::ValueId value) const {
+  CHECK_LT(value.value_id, nodes_.size());
+  CHECK_NOT_NULL(nodes_.at(value.value_id));
+  return nodes_.at(value.value_id);
+}
+
+
+RawMachineLabel* FastAccessorAssembler::FromId(
+    FastAccessorAssembler::LabelId label) const {
+  CHECK_LT(label.label_id, labels_.size());
+  CHECK_NOT_NULL(labels_.at(label.label_id));
+  return labels_.at(label.label_id);
+}
+
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8