Reviewers: Benedikt Meurer,
Message:
PTAL
Description:
ARM64: do not optimize away shift if its result is used as both left and
right
arguments.
BUG=chromium:491049
LOG=NO
TEST=mjsunit/regress/regress-491049.js
Please review this at https://codereview.chromium.org/1150683004/
Base URL: https://chromium.googlesource.com/v8/v8.git@master
Affected files (+10, -6 lines):
M src/arm64/lithium-arm64.cc
A + test/mjsunit/regress/regress-491049.js
Index: src/arm64/lithium-arm64.cc
diff --git a/src/arm64/lithium-arm64.cc b/src/arm64/lithium-arm64.cc
index
91b4430566060e90a1241a0ba25c366dbe510cb9..a9d661d35d2f5a3eb7162c38fd12231136a90ef1
100644
--- a/src/arm64/lithium-arm64.cc
+++ b/src/arm64/lithium-arm64.cc
@@ -2126,6 +2126,11 @@ HBitwiseBinaryOperation*
LChunkBuilder::CanTransformToShiftedOp(HValue* val,
DCHECK(hleft->representation().Equals(hinstr->representation()));
DCHECK(hright->representation().Equals(hinstr->representation()));
+ if (hleft == hright) {
+ // Cannot replace two operands at once.
+ return NULL;
+ }
+
if ((hright->IsConstant() &&
LikelyFitsImmField(hinstr,
HConstant::cast(hright)->Integer32Value())) ||
(hinstr->IsCommutative() && hleft->IsConstant() &&
Index: test/mjsunit/regress/regress-491049.js
diff --git a/test/mjsunit/regress/regress-filter-contexts.js
b/test/mjsunit/regress/regress-491049.js
similarity index 66%
copy from test/mjsunit/regress/regress-filter-contexts.js
copy to test/mjsunit/regress/regress-491049.js
index
d2abe0032548428324afd6675a7031bf53a5e56e..c010b0911dcd5f700406a5950d05e16055979857
100644
--- a/test/mjsunit/regress/regress-filter-contexts.js
+++ b/test/mjsunit/regress/regress-491049.js
@@ -2,13 +2,12 @@
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
-// Flags: --allow-natives-syntax
+function f(a) {
+ return (a >>> 12) + (a >>> 2);
+}
-function f() { return f.x; }
-f.__proto__ = null;
-f.prototype = "";
-
-f();
f();
+
%OptimizeFunctionOnNextCall(f);
+
f();
--
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