Revision: 25023
Author: [email protected]
Date: Thu Oct 30 15:52:26 2014 UTC
Log: Fix bug in optimization of Uint32LessThan.
[email protected]
BUG=
Review URL: https://codereview.chromium.org/689883003
https://code.google.com/p/v8/source/detail?r=25023
Added:
/branches/bleeding_edge/test/mjsunit/asm/uint32-less-than-shift.js
Modified:
/branches/bleeding_edge/src/compiler/machine-operator-reducer.cc
/branches/bleeding_edge/test/unittests/compiler/machine-operator-reducer-unittest.cc
=======================================
--- /dev/null
+++ /branches/bleeding_edge/test/mjsunit/asm/uint32-less-than-shift.js Thu
Oct 30 15:52:26 2014 UTC
@@ -0,0 +1,61 @@
+// 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.
+
+function Module(stdlib, foreign, heap) {
+ 'use asm';
+
+ function foo1(i1) {
+ i1 = i1 | 0;
+ var i10 = i1 >> 5;
+ if (i10 >>> 0 < 5) {
+ return 1;
+ } else {
+ return 0;
+ }
+ return 0;
+ }
+
+ function foo2(i1) {
+ i1 = i1 | 0;
+ var i10 = i1 / 32 | 0;
+ if (i10 >>> 0 < 5) {
+ return 1;
+ } else {
+ return 0;
+ }
+ return 0;
+ }
+
+ function foo3(i1) {
+ i1 = i1 | 0;
+ var i10 = (i1 + 32 | 0) / 32 | 0;
+ if (i10 >>> 0 < 5) {
+ return 1;
+ } else {
+ return 0;
+ }
+ return 0;
+ }
+ return {foo1: foo1, foo2: foo2, foo3: foo3};
+}
+
+var m = Module(this, {}, undefined);
+
+for (var i = 0; i < 4 * 32; i++) {
+ assertEquals(1, m.foo1(i));
+ assertEquals(1, m.foo2(i));
+ assertEquals(1, m.foo3(i));
+}
+
+for (var i = 4 * 32; i < 5 * 32; i++) {
+ assertEquals(1, m.foo1(i));
+ assertEquals(1, m.foo2(i));
+ assertEquals(0, m.foo3(i));
+}
+
+for (var i = 5 * 32; i < 10 * 32; i++) {
+ assertEquals(0, m.foo1(i));
+ assertEquals(0, m.foo2(i));
+ assertEquals(0, m.foo3(i));
+}
=======================================
--- /branches/bleeding_edge/src/compiler/machine-operator-reducer.cc Wed
Oct 29 21:07:18 2014 UTC
+++ /branches/bleeding_edge/src/compiler/machine-operator-reducer.cc Thu
Oct 30 15:52:26 2014 UTC
@@ -370,15 +370,16 @@
if (m.left().IsWord32Sar() && m.right().HasValue()) {
Int32BinopMatcher mleft(m.left().node());
if (mleft.right().HasValue()) {
- // (x >> K) < C => x < (C << K) | (2^K - 1)
+ // (x >> K) < C => x < (C << K)
// when C < (M >> K)
const uint32_t c = m.right().Value();
const uint32_t k = mleft.right().Value() & 0x1f;
if (c < static_cast<uint32_t>(kMaxInt >> k)) {
node->ReplaceInput(0, mleft.left().node());
- node->ReplaceInput(1, Uint32Constant((c << k) | ((1 << k) -
1)));
+ node->ReplaceInput(1, Uint32Constant(c << k));
return Changed(node);
}
+ // TODO(turbofan): else the comparison is always true.
}
}
break;
=======================================
---
/branches/bleeding_edge/test/unittests/compiler/machine-operator-reducer-unittest.cc
Tue Oct 28 11:57:20 2014 UTC
+++
/branches/bleeding_edge/test/unittests/compiler/machine-operator-reducer-unittest.cc
Thu Oct 30 15:52:26 2014 UTC
@@ -1089,10 +1089,9 @@
Reduction r = Reduce(node);
ASSERT_TRUE(r.Changed());
- EXPECT_THAT(
- r.replacement(),
- IsUint32LessThan(p0, IsInt32Constant(bit_cast<int32_t>(
- (limit << shift) | ((1u << shift) -
1)))));
+ EXPECT_THAT(r.replacement(),
+ IsUint32LessThan(
+ p0, IsInt32Constant(bit_cast<int32_t>(limit <<
shift))));
}
}
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