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[turbofan] Canonicalize x - K to x + -K.

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TEST=unittests
R=dcarney@chromium.org

Review URL: https://codereview.chromium.org/846913002

Cr-Commit-Position: refs/heads/master@{#26027}
This commit is contained in:
bmeurer 2015-01-12 07:01:58 -08:00 committed by Commit bot
parent df30088de3
commit 0e8a6d4ec8
3 changed files with 44 additions and 11 deletions
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35
src/compiler/machine-operator-reducer.cc
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@ -75,7 +75,9 @@ Node* MachineOperatorReducer::Int32Add(Node* lhs, Node* rhs) {
Node* MachineOperatorReducer::Int32Sub(Node* lhs, Node* rhs) {
return graph()->NewNode(machine()->Int32Sub(), lhs, rhs);
Node* const node = graph()->NewNode(machine()->Int32Sub(), lhs, rhs);
Reduction const reduction = ReduceInt32Sub(node);
return reduction.Changed() ? reduction.replacement() : node;
}
@ -216,16 +218,8 @@ Reduction MachineOperatorReducer::Reduce(Node* node) {
}
case IrOpcode::kInt32Add:
return ReduceInt32Add(node);
case IrOpcode::kInt32Sub: {
Int32BinopMatcher m(node);
if (m.right().Is(0)) return Replace(m.left().node()); // x - 0 => x
if (m.IsFoldable()) { // K - K => K
return ReplaceInt32(static_cast<uint32_t>(m.left().Value()) -
static_cast<uint32_t>(m.right().Value()));
}
if (m.LeftEqualsRight()) return ReplaceInt32(0); // x - x => 0
break;
}
case IrOpcode::kInt32Sub:
return ReduceInt32Sub(node);
case IrOpcode::kInt32Mul: {
Int32BinopMatcher m(node);
if (m.right().Is(0)) return Replace(m.right().node()); // x * 0 => 0
@ -475,6 +469,25 @@ Reduction MachineOperatorReducer::ReduceInt32Add(Node* node) {
}
Reduction MachineOperatorReducer::ReduceInt32Sub(Node* node) {
DCHECK_EQ(IrOpcode::kInt32Sub, node->opcode());
Int32BinopMatcher m(node);
if (m.right().Is(0)) return Replace(m.left().node()); // x - 0 => x
if (m.IsFoldable()) { // K - K => K
return ReplaceInt32(static_cast<uint32_t>(m.left().Value()) -
static_cast<uint32_t>(m.right().Value()));
}
if (m.LeftEqualsRight()) return ReplaceInt32(0); // x - x => 0
if (m.right().HasValue()) { // x - K => x + -K
node->set_op(machine()->Int32Add());
node->ReplaceInput(1, Int32Constant(-m.right().Value()));
Reduction const reduction = ReduceInt32Add(node);
return reduction.Changed() ? reduction : Changed(node);
}
return NoChange();
}
Reduction MachineOperatorReducer::ReduceInt32Div(Node* node) {
Int32BinopMatcher m(node);
if (m.left().Is(0)) return Replace(m.left().node()); // 0 / x => 0

1
src/compiler/machine-operator-reducer.h
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@ -65,6 +65,7 @@ class MachineOperatorReducer FINAL : public Reducer {
}
Reduction ReduceInt32Add(Node* node);
Reduction ReduceInt32Sub(Node* node);
Reduction ReduceInt32Div(Node* node);
Reduction ReduceUint32Div(Node* node);
Reduction ReduceInt32Mod(Node* node);

19
test/unittests/compiler/machine-operator-reducer-unittest.cc
View File

@ -841,6 +841,25 @@ TEST_F(MachineOperatorReducerTest, Word32ShlWithWord32Shr) {
}
// -----------------------------------------------------------------------------
// Int32Sub
TEST_F(MachineOperatorReducerTest, Int32SubWithConstant) {
Node* const p0 = Parameter(0);
TRACED_FOREACH(int32_t, k, kInt32Values) {
Reduction const r =
Reduce(graph()->NewNode(machine()->Int32Sub(), p0, Int32Constant(k)));
ASSERT_TRUE(r.Changed());
if (k == 0) {
EXPECT_EQ(p0, r.replacement());
} else {
EXPECT_THAT(r.replacement(), IsInt32Add(p0, IsInt32Constant(-k)));
}
}
}
// -----------------------------------------------------------------------------
// Int32Div