Reviewers: Sven Panne,
Description:
[turbofan] Avoid useless sign extension after sign extended load.
TEST=unittests
[email protected]
Please review this at https://codereview.chromium.org/735623002/
Base URL: https://chromium.googlesource.com/v8/v8.git@master
Affected files (+45, -0 lines):
M src/compiler/machine-operator-reducer.cc
M test/unittests/compiler/machine-operator-reducer-unittest.cc
Index: src/compiler/machine-operator-reducer.cc
diff --git a/src/compiler/machine-operator-reducer.cc
b/src/compiler/machine-operator-reducer.cc
index
bb1596f58bd93e74e8467555f6053cf2988dca49..f788cb54bc272e7da48fcda64169997095f7d95a
100644
--- a/src/compiler/machine-operator-reducer.cc
+++ b/src/compiler/machine-operator-reducer.cc
@@ -250,6 +250,21 @@ Reduction MachineOperatorReducer::Reduce(Node* node) {
if (m.IsFoldable()) { // K >> K => K
return ReplaceInt32(m.left().Value() >> m.right().Value());
}
+ if (m.left().IsWord32Shl()) {
+ Int32BinopMatcher mleft(m.left().node());
+ if (mleft.left().IsLoad()) {
+ LoadRepresentation const rep =
+ OpParameter<LoadRepresentation>(mleft.left().node());
+ if (m.right().Is(24) && mleft.right().Is(24) && rep ==
kMachInt8) {
+ // Load[kMachInt8] << 24 >> 24 => Load[kMachInt8]
+ return Replace(mleft.left().node());
+ }
+ if (m.right().Is(16) && mleft.right().Is(16) && rep ==
kMachInt16) {
+ // Load[kMachInt16] << 16 >> 16 => Load[kMachInt8]
+ return Replace(mleft.left().node());
+ }
+ }
+ }
break;
}
case IrOpcode::kWord32Ror: {
Index: test/unittests/compiler/machine-operator-reducer-unittest.cc
diff --git a/test/unittests/compiler/machine-operator-reducer-unittest.cc
b/test/unittests/compiler/machine-operator-reducer-unittest.cc
index
065a734e2038257a15ff58de0a048d16987e80d1..1284c566a3431d75b20407bbaf1252e19b360df2
100644
--- a/test/unittests/compiler/machine-operator-reducer-unittest.cc
+++ b/test/unittests/compiler/machine-operator-reducer-unittest.cc
@@ -645,6 +645,36 @@ TEST_F(MachineOperatorReducerTest,
Word32RorWithConstants) {
//
-----------------------------------------------------------------------------
+// Word32Sar
+
+
+TEST_F(MachineOperatorReducerTest, Word32SarWithWord32ShlAndLoad) {
+ Node* const p0 = Parameter(0);
+ Node* const p1 = Parameter(1);
+ {
+ Node* const l = graph()->NewNode(machine()->Load(kMachInt8), p0, p1,
+ graph()->start(), graph()->start());
+ Reduction const r = Reduce(graph()->NewNode(
+ machine()->Word32Sar(),
+ graph()->NewNode(machine()->Word32Shl(), l, Int32Constant(24)),
+ Int32Constant(24)));
+ ASSERT_TRUE(r.Changed());
+ EXPECT_EQ(l, r.replacement());
+ }
+ {
+ Node* const l = graph()->NewNode(machine()->Load(kMachInt16), p0, p1,
+ graph()->start(), graph()->start());
+ Reduction const r = Reduce(graph()->NewNode(
+ machine()->Word32Sar(),
+ graph()->NewNode(machine()->Word32Shl(), l, Int32Constant(16)),
+ Int32Constant(16)));
+ ASSERT_TRUE(r.Changed());
+ EXPECT_EQ(l, r.replacement());
+ }
+}
+
+
+//
-----------------------------------------------------------------------------
// Word32Shl
--
--
v8-dev mailing list
[email protected]
http://groups.google.com/group/v8-dev
---
You received this message because you are subscribed to the Google Groups "v8-dev" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
For more options, visit https://groups.google.com/d/optout.
