Initial import of ChangeLowering.

src/compiler/change-lowering.cc

+// Copyright 2014 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/change-lowering.h"
+
+#include "src/compiler/common-node-cache.h"
+#include "src/compiler/graph.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+ChangeLoweringBase::ChangeLoweringBase(Graph* graph, Linkage* linkage,
+                                       CommonNodeCache* cache)
+    : graph_(graph),
+      isolate_(graph->zone()->isolate()),
+      linkage_(linkage),
+      cache_(cache),
+      common_(graph->zone()),
+      machine_(graph->zone()) {}
+
+
+ChangeLoweringBase::~ChangeLoweringBase() {}
+
+
+Node* ChangeLoweringBase::ExternalConstant(ExternalReference reference) {

[titzer, 2014/08/13 08:59:47]

This is a big duplication of code. Why didn't you keep the original code with
used JSGraph instead?

+  Node** loc = cache()->FindExternalConstant(reference);
+  if (*loc == NULL) {
+    *loc = graph()->NewNode(common()->ExternalConstant(reference));
+  }
+  return *loc;
+}
+
+
+Node* ChangeLoweringBase::HeapConstant(PrintableUnique<HeapObject> value) {
+  // TODO(bmeurer): Use common node cache.
+  return graph()->NewNode(common()->HeapConstant(value));
+}
+
+
+Node* ChangeLoweringBase::ImmovableHeapConstant(Handle<HeapObject> value) {
+  return HeapConstant(
+      PrintableUnique<HeapObject>::CreateImmovable(graph()->zone(), value));
+}
+
+
+Node* ChangeLoweringBase::Int32Constant(int32_t value) {
+  Node** loc = cache()->FindInt32Constant(value);
+  if (*loc == NULL) {
+    *loc = graph()->NewNode(common()->Int32Constant(value));
+  }
+  return *loc;
+}
+
+
+Node* ChangeLoweringBase::NumberConstant(double value) {
+  Node** loc = cache()->FindNumberConstant(value);
+  if (*loc == NULL) {
+    *loc = graph()->NewNode(common()->NumberConstant(value));
+  }
+  return *loc;
+}
+
+
+Node* ChangeLoweringBase::CEntryStubConstant() {
+  if (!c_entry_stub_constant_.is_set()) {
+    c_entry_stub_constant_.set(
+        ImmovableHeapConstant(CEntryStub(isolate(), 1).GetCode()));
+  }
+  return c_entry_stub_constant_.get();
+}
+
+
+Node* ChangeLoweringBase::TrueConstant() {
+  if (!true_constant_.is_set()) {
+    true_constant_.set(
+        ImmovableHeapConstant(isolate()->factory()->true_value()));
+  }
+  return true_constant_.get();
+}
+
+
+Node* ChangeLoweringBase::FalseConstant() {
+  if (!false_constant_.is_set()) {
+    false_constant_.set(
+        ImmovableHeapConstant(isolate()->factory()->false_value()));
+  }
+  return false_constant_.get();
+}
+
+
+Reduction ChangeLoweringBase::ChangeBitToBool(Node* val, Node* control) {
+  Node* branch = graph()->NewNode(common()->Branch(), val, control);
+
+  Node* if_true = graph()->NewNode(common()->IfTrue(), branch);
+  Node* true_value = TrueConstant();
+
+  Node* if_false = graph()->NewNode(common()->IfFalse(), branch);
+  Node* false_value = FalseConstant();
+
+  Node* merge = graph()->NewNode(common()->Merge(2), if_true, if_false);
+  Node* phi =
+      graph()->NewNode(common()->Phi(2), true_value, false_value, merge);
+
+  return Replace(phi);
+}
+
+
+template <size_t kPointerSize>
+ChangeLowering<kPointerSize>::ChangeLowering(Graph* graph, Linkage* linkage)
+    : ChangeLoweringBase(graph, linkage,
+                         new (graph->zone()) CommonNodeCache(graph->zone())) {}
+
+
+template <size_t kPointerSize>
+Reduction ChangeLowering<kPointerSize>::Reduce(Node* node) {
+  Node* control = graph()->start();
+  Node* effect = control;
+  switch (node->opcode()) {
+    case IrOpcode::kChangeBitToBool:
+      return ChangeBitToBool(node->InputAt(0), control);
+    case IrOpcode::kChangeBoolToBit:
+      return ChangeBoolToBit(node->InputAt(0));
+    case IrOpcode::kChangeInt32ToTagged:
+      return ChangeInt32ToTagged(node->InputAt(0), effect, control);
+    case IrOpcode::kChangeTaggedToFloat64:
+      return ChangeTaggedToFloat64(node->InputAt(0), effect, control);
+    default:
+      return NoChange();
+  }
+  UNREACHABLE();
+  return NoChange();
+}
+
+
+template <>
+Reduction ChangeLowering<4>::ChangeBoolToBit(Node* val) {

[titzer, 2014/08/13 08:59:47]

This templatization of the changes is unnecessary complexity. The original code
had a simple branch on the pointer size.

[Benedikt Meurer, 2014/08/13 09:03:41]

Before it was simple and not unit testable because it depends on some global
state. Now it's simple and unit testable.

[titzer, 2014/08/13 09:11:12]

You could, e.g. make the pointer size a field on the class, and then you don't
need to templatize it.

[Benedikt Meurer, 2014/08/13 09:14:12]

That's another option, sure. But I decided to do it this way.

+  return Replace(
+      graph()->NewNode(machine()->Word32Equal(), val, TrueConstant()));
+}
+
+
+template <>
+Reduction ChangeLowering<8>::ChangeBoolToBit(Node* val) {
+  return Replace(
+      graph()->NewNode(machine()->Word64Equal(), val, TrueConstant()));
+}
+
+
+template <>
+Reduction ChangeLowering<4>::ChangeInt32ToTagged(Node* val, Node* effect,
+                                                 Node* control) {
+  Node* context = NumberConstant(0);
+
+  Node* add = graph()->NewNode(machine()->Int32AddWithOverflow(), val, val);
+  Node* ovf = graph()->NewNode(common()->Projection(1), add);
+
+  Node* branch = graph()->NewNode(common()->Branch(), ovf, control);
+
+  Node* if_true = graph()->NewNode(common()->IfTrue(), branch);
+  Node* number = graph()->NewNode(machine()->ChangeInt32ToFloat64(), val);
+
+  // TODO(bmeurer): Inline allocation if possible.
+  const Runtime::Function* fn =
+      Runtime::FunctionForId(Runtime::kAllocateHeapNumber);
+  DCHECK_EQ(0, fn->nargs);
+  CallDescriptor* desc = linkage()->GetRuntimeCallDescriptor(
+      fn->function_id, 0, Operator::kNoProperties);
+  Node* heap_number =
+      graph()->NewNode(common()->Call(desc), CEntryStubConstant(),
+                       ExternalConstant(ExternalReference(fn, isolate())),
+                       Int32Constant(0), context, effect, if_true);
+
+  Node* store = graph()->NewNode(
+      machine()->Store(kMachineFloat64, kNoWriteBarrier), heap_number,
+      Int32Constant(HeapNumber::kValueOffset - kHeapObjectTag), number, effect,
+      heap_number);
+
+  Node* if_false = graph()->NewNode(common()->IfFalse(), branch);
+  Node* smi = graph()->NewNode(common()->Projection(0), add);
+
+  Node* merge = graph()->NewNode(common()->Merge(2), store, if_false);
+  Node* phi = graph()->NewNode(common()->Phi(2), heap_number, smi, merge);
+
+  return Replace(phi);
+}
+
+
+template <>
+Reduction ChangeLowering<8>::ChangeInt32ToTagged(Node* val, Node* effect,
+                                                 Node* control) {
+  return Replace(graph()->NewNode(
+      machine()->Word64Shl(), val,
+      Int32Constant(SmiTagging<8>::kSmiShiftSize + kSmiTagSize)));
+}
+
+
+template <>
+Reduction ChangeLowering<4>::ChangeTaggedToFloat64(Node* val, Node* effect,

[titzer, 2014/08/13 08:59:47]

ChangeLowering<4> and ChangeLowering<8> of this method are almost exactly alike.

[Benedikt Meurer, 2014/08/13 09:03:41]

Yap, will be refactored once everythings in place.

+                                                   Node* control) {
+  Node* branch = graph()->NewNode(
+      common()->Branch(),
+      graph()->NewNode(machine()->Word32And(), val, Int32Constant(kSmiTagMask)),
+      control);
+
+  Node* if_true = graph()->NewNode(common()->IfTrue(), branch);
+  Node* load = graph()->NewNode(
+      machine()->Load(kMachineFloat64), val,
+      Int32Constant(HeapNumber::kValueOffset - kHeapObjectTag), if_true);
+
+  Node* if_false = graph()->NewNode(common()->IfFalse(), branch);
+  Node* number = graph()->NewNode(
+      machine()->ChangeInt32ToFloat64(),
+      graph()->NewNode(
+          machine()->Word32Sar(), val,
+          Int32Constant(SmiTagging<4>::kSmiShiftSize + kSmiTagSize)));
+
+  Node* merge = graph()->NewNode(common()->Merge(2), if_true, if_false);
+  Node* phi = graph()->NewNode(common()->Phi(2), load, number, merge);
+
+  return Replace(phi);
+}
+
+
+template <>
+Reduction ChangeLowering<8>::ChangeTaggedToFloat64(Node* val, Node* effect,
+                                                   Node* control) {
+  Node* branch = graph()->NewNode(
+      common()->Branch(),
+      graph()->NewNode(machine()->Word64And(), val, Int32Constant(kSmiTagMask)),
+      control);
+
+  Node* if_true = graph()->NewNode(common()->IfTrue(), branch);
+  Node* load = graph()->NewNode(
+      machine()->Load(kMachineFloat64), val,
+      Int32Constant(HeapNumber::kValueOffset - kHeapObjectTag), if_true);
+
+  Node* if_false = graph()->NewNode(common()->IfFalse(), branch);
+  Node* number = graph()->NewNode(
+      machine()->ChangeInt32ToFloat64(),
+      graph()->NewNode(
+          machine()->ConvertInt64ToInt32(),
+          graph()->NewNode(
+              machine()->Word64Sar(), val,
+              Int32Constant(SmiTagging<8>::kSmiShiftSize + kSmiTagSize))));
+
+  Node* merge = graph()->NewNode(common()->Merge(2), if_true, if_false);
+  Node* phi = graph()->NewNode(common()->Phi(2), load, number, merge);
+
+  return Replace(phi);
+}
+
+
+template class ChangeLowering<4>;
+template class ChangeLowering<8>;
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8