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[turbofan] Decide lowering for NumberDivide based on feedback.

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Again in the spirit of https://chromium-review.googlesource.com/1226033
we can simplify the handling of NumberDivide and decide the lowering
based on the feedback type.

Drive-by-fix: Add test coverage for the relevant corner cases of the
NumberDivide handling in SimplifiedLowering.

Bug: v8:8015
Change-Id: I0edaca0fddb31d64d2c269268e87a32a687a0b26
Reviewed-on: https://chromium-review.googlesource.com/1236262
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56113}
This commit is contained in:
Benedikt Meurer 2018-09-20 20:25:29 +02:00 committed by Commit Bot
parent b57a87749f
commit 8c1a7c5ec5
2 changed files with 75 additions and 14 deletions
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26
src/compiler/simplified-lowering.cc
View File

@ -1954,25 +1954,23 @@ class RepresentationSelector {
return;
}
case IrOpcode::kNumberDivide: {
if (BothInputsAreUnsigned32(node) && truncation.IsUsedAsWord32()) {
if (TypeOf(node->InputAt(0)).Is(Type::Unsigned32()) &&
TypeOf(node->InputAt(1)).Is(Type::Unsigned32()) &&
(truncation.IsUsedAsWord32() ||
TypeOf(node).Is(Type::Unsigned32()))) {
// => unsigned Uint32Div
VisitWord32TruncatingBinop(node);
if (lower()) DeferReplacement(node, lowering->Uint32Div(node));
return;
}
if (BothInputsAreSigned32(node)) {
if (NodeProperties::GetType(node).Is(Type::Signed32())) {
// => signed Int32Div
VisitWord32TruncatingBinop(node);
if (lower()) DeferReplacement(node, lowering->Int32Div(node));
return;
}
if (truncation.IsUsedAsWord32()) {
// => signed Int32Div
VisitWord32TruncatingBinop(node);
if (lower()) DeferReplacement(node, lowering->Int32Div(node));
return;
}
if (TypeOf(node->InputAt(0)).Is(Type::Signed32()) &&
TypeOf(node->InputAt(1)).Is(Type::Signed32()) &&
(truncation.IsUsedAsWord32() ||
TypeOf(node).Is(Type::Signed32()))) {
// => signed Int32Div
VisitWord32TruncatingBinop(node);
if (lower()) DeferReplacement(node, lowering->Int32Div(node));
return;
}
// Number x Number => Float64Div
VisitFloat64Binop(node);

63
test/mjsunit/compiler/number-divide.js Normal file
View File

@ -0,0 +1,63 @@
// Copyright 2018 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.
// Flags: --allow-natives-syntax --opt
// Test that NumberDivide with Number feedback works if only in the
// end SimplifiedLowering figures out that the inputs to this operation
// are actually Unsigned32.
(function() {
// We need a separately polluted % with NumberOrOddball feedback.
function bar(x) { return x / 2; }
bar(undefined); // The % feedback is now NumberOrOddball.
// Now just use the gadget above in a way that only after RETYPE
// in SimplifiedLowering we find out that the `x` is actually in
// Unsigned32 range (based on taking the SignedSmall feedback on
// the + operator).
function foo(x) {
x = (x >>> 0) + 1;
return bar(x) | 0;
}
assertEquals(1, foo(1));
assertEquals(1, foo(2));
assertEquals(2, foo(3));
assertEquals(2, foo(4));
%OptimizeFunctionOnNextCall(foo);
assertEquals(1, foo(1));
assertEquals(1, foo(2));
assertEquals(2, foo(3));
assertEquals(2, foo(4));
assertOptimized(foo);
})();
// Test that NumberDivide with Number feedback works if only in the
// end SimplifiedLowering figures out that the inputs to this operation
// are actually Signed32.
(function() {
// We need a separately polluted % with NumberOrOddball feedback.
function bar(x) { return x / 2; }
bar(undefined); // The % feedback is now NumberOrOddball.
// Now just use the gadget above in a way that only after RETYPE
// in SimplifiedLowering we find out that the `x` is actually in
// Signed32 range (based on taking the SignedSmall feedback on
// the + operator).
function foo(x) {
x = (x | 0) + 1;
return bar(x) | 0;
}
assertEquals(1, foo(1));
assertEquals(1, foo(2));
assertEquals(2, foo(3));
assertEquals(2, foo(4));
%OptimizeFunctionOnNextCall(foo);
assertEquals(1, foo(1));
assertEquals(1, foo(2));
assertEquals(2, foo(3));
assertEquals(2, foo(4));
assertOptimized(foo);
})();