0a36b5cd2c
After multiplying two integers we emit code like:
if (result == 0) {
if (OR_OPERATION(rhs, lhs) < 0) {
DEOPT;
}
}
This CL allows us to eliminate the OR and comparison if either rhs or
lhs is a negative number, reducing the code to:
if (result == 0) DEOPT;
BUG=
Review-Url: https://codereview.chromium.org/2167643002
Cr-Commit-Position: refs/heads/master@{#38016}
46 lines
1.4 KiB
JavaScript
46 lines
1.4 KiB
JavaScript
// Copyright 2016 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// Flags: --allow-natives-syntax
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// For TurboFan, make sure we can eliminate the -0 return value check
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// by recognizing a constant value.
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function gotaconstant(y) { return 15 * y; }
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assertEquals(45, gotaconstant(3));
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gotaconstant(3);
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%OptimizeFunctionOnNextCall(gotaconstant);
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gotaconstant(3);
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function gotaconstant_truncated(x, y) { return x * y | 0; }
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assertEquals(45, gotaconstant_truncated(3, 15));
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gotaconstant_truncated(3, 15);
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%OptimizeFunctionOnNextCall(gotaconstant_truncated);
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gotaconstant_truncated(3, 15);
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function test(x, y) { return x * y; }
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assertEquals(12, test(3, 4));
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assertEquals(16, test(4, 4));
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%OptimizeFunctionOnNextCall(test);
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assertEquals(27, test(9, 3));
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assertEquals(-0, test(-3, 0));
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assertEquals(-0, test(0, -0));
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const SMI_MAX = (1 << 29) - 1 + (1 << 29); // Create without overflowing.
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const SMI_MIN = -SMI_MAX - 1; // Create without overflowing.
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// multiply by 3 to avoid compiler optimizations that convert 2*x to x + x.
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assertEquals(SMI_MAX + SMI_MAX + SMI_MAX, test(SMI_MAX, 3));
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// Verify that strength reduction will reduce the -0 check quite a bit
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// if we have a negative integer constant.
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function negtest(y) { return -3 * y; }
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assertEquals(-12, negtest(4));
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assertEquals(-12, negtest(4));
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%OptimizeFunctionOnNextCall(negtest);
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negtest(4);
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