Revision: 16943
Author: [email protected]
Date: Wed Sep 25 15:10:48 2013 UTC
Log: Special handle for mul/div minus one when
kAllUsesTruncatingToInt32
BUG=
[email protected]
Review URL: https://chromiumcodereview.appspot.com/24521002
http://code.google.com/p/v8/source/detail?r=16943
Added:
/branches/bleeding_edge/test/mjsunit/div-mul-minus-one.js
Modified:
/branches/bleeding_edge/src/hydrogen-instructions.cc
/branches/bleeding_edge/src/hydrogen-instructions.h
=======================================
--- /dev/null
+++ /branches/bleeding_edge/test/mjsunit/div-mul-minus-one.js Wed Sep 25
15:10:48 2013 UTC
@@ -0,0 +1,53 @@
+// Copyright 2013 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following
+// disclaimer in the documentation and/or other materials provided
+// with the distribution.
+// * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived
+// from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --allow-natives-syntax
+
+function div(g) {
+ return (g/-1) ^ 1
+}
+
+var kMinInt = 1 << 31;
+var expected_MinInt = div(kMinInt);
+var expected_minus_zero = div(0);
+%OptimizeFunctionOnNextCall(div);
+assertEquals(expected_MinInt, div(kMinInt));
+assertOptimized(div);
+assertEquals(expected_minus_zero , div(0));
+assertOptimized(div);
+
+function mul(g) {
+ return (g * -1) ^ 1
+}
+
+expected_MinInt = mul(kMinInt);
+expected_minus_zero = mul(0);
+%OptimizeFunctionOnNextCall(mul);
+assertEquals(expected_MinInt, mul(kMinInt));
+assertOptimized(mul);
+assertEquals(expected_minus_zero , mul(0));
+assertOptimized(mul);
=======================================
--- /branches/bleeding_edge/src/hydrogen-instructions.cc Tue Sep 24
09:48:39 2013 UTC
+++ /branches/bleeding_edge/src/hydrogen-instructions.cc Wed Sep 25
15:10:48 2013 UTC
@@ -1235,6 +1235,16 @@
if (IsIdentityOperation(right(), left(), 1)) return right();
return this;
}
+
+
+bool HMul::MulMinusOne() {
+ if (left()->EqualsInteger32Constant(-1) ||
+ right()->EqualsInteger32Constant(-1)) {
+ return true;
+ }
+
+ return false;
+}
HValue* HMod::Canonicalize() {
@@ -1622,10 +1632,13 @@
Range* a = left()->range();
Range* b = right()->range();
Range* res = a->Copy(zone);
- if (!res->MulAndCheckOverflow(r, b)) {
- // Clearing the kCanOverflow flag when kAllUsesAreTruncatingToInt32
- // would be wrong, because truncated integer multiplication is too
- // precise and therefore not the same as converting to Double and
back.
+ if (!res->MulAndCheckOverflow(r, b) ||
+ (((r.IsInteger32() && CheckFlag(kAllUsesTruncatingToInt32)) ||
+ (r.IsSmi() && CheckFlag(kAllUsesTruncatingToSmi))) &&
+ MulMinusOne())) {
+ // Truncated int multiplication is too precise and therefore not the
+ // same as converting to Double and back.
+ // Handle truncated integer multiplication by -1 special.
ClearFlag(kCanOverflow);
}
res->set_can_be_minus_zero(!CheckFlag(kAllUsesTruncatingToSmi) &&
@@ -1647,7 +1660,10 @@
result->set_can_be_minus_zero(!CheckFlag(kAllUsesTruncatingToInt32) &&
(a->CanBeMinusZero() ||
(a->CanBeZero() &&
b->CanBeNegative())));
- if (!a->Includes(kMinInt) || !b->Includes(-1)) {
+ if (!a->Includes(kMinInt) ||
+ !b->Includes(-1) ||
+ CheckFlag(kAllUsesTruncatingToInt32)) {
+ // It is safe to clear kCanOverflow when kAllUsesTruncatingToInt32.
ClearFlag(HValue::kCanOverflow);
}
@@ -2596,6 +2612,12 @@
ASSERT(CheckFlag(kFlexibleRepresentation));
Representation new_rep = RepresentationFromInputs();
UpdateRepresentation(new_rep, h_infer, "inputs");
+
+ if (representation().IsSmi() && HasNonSmiUse()) {
+ UpdateRepresentation(
+ Representation::Integer32(), h_infer, "use requirements");
+ }
+
if (observed_output_representation_.IsNone()) {
new_rep = RepresentationFromUses();
UpdateRepresentation(new_rep, h_infer, "uses");
@@ -2603,11 +2625,6 @@
new_rep = RepresentationFromOutput();
UpdateRepresentation(new_rep, h_infer, "output");
}
-
- if (representation().IsSmi() && HasNonSmiUse()) {
- UpdateRepresentation(
- Representation::Integer32(), h_infer, "use requirements");
- }
}
@@ -2634,7 +2651,7 @@
return ((current_rep.IsInteger32() &&
CheckUsesForFlag(kTruncatingToInt32)) ||
(current_rep.IsSmi() && CheckUsesForFlag(kTruncatingToSmi))) &&
// Mul in Integer32 mode would be too precise.
- !this->IsMul();
+ (!this->IsMul() || HMul::cast(this)->MulMinusOne());
}
=======================================
--- /branches/bleeding_edge/src/hydrogen-instructions.h Wed Sep 25 11:57:20
2013 UTC
+++ /branches/bleeding_edge/src/hydrogen-instructions.h Wed Sep 25 15:10:48
2013 UTC
@@ -4580,6 +4580,8 @@
const char* reason) V8_OVERRIDE {
HArithmeticBinaryOperation::UpdateRepresentation(new_rep, h_infer,
reason);
}
+
+ bool MulMinusOne();
DECLARE_CONCRETE_INSTRUCTION(Mul)
--
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