v8/test/mjsunit/compiler/math-mul.js

// Copyright 2016 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

// For TurboFan, make sure we can eliminate the -0 return value check
// by recognizing a constant value.
function gotaconstant(y) { return 15 * y; }
%PrepareFunctionForOptimization(gotaconstant);
assertEquals(45, gotaconstant(3));
gotaconstant(3);
%OptimizeFunctionOnNextCall(gotaconstant);
gotaconstant(3);

function gotaconstant_truncated(x, y) { return x * y | 0; }
%PrepareFunctionForOptimization(gotaconstant_truncated);
assertEquals(45, gotaconstant_truncated(3, 15));
gotaconstant_truncated(3, 15);
%OptimizeFunctionOnNextCall(gotaconstant_truncated);
gotaconstant_truncated(3, 15);

function test(x, y) { return x * y; }

%PrepareFunctionForOptimization(test);
assertEquals(12, test(3, 4));
assertEquals(16, test(4, 4));

%OptimizeFunctionOnNextCall(test);
assertEquals(27, test(9, 3));

assertEquals(-0, test(-3, 0));
assertEquals(-0, test(0, -0));


const SMI_MAX = (1 << 29) - 1 + (1 << 29);  // Create without overflowing.
const SMI_MIN = -SMI_MAX - 1;  // Create without overflowing.

// multiply by 3 to avoid compiler optimizations that convert 2*x to x + x.
assertEquals(SMI_MAX + SMI_MAX + SMI_MAX, test(SMI_MAX, 3));

// Verify that strength reduction will reduce the -0 check quite a bit
// if we have a negative integer constant.
function negtest(y) { return -3 * y; }
%PrepareFunctionForOptimization(negtest);
assertEquals(-12, negtest(4));
assertEquals(-12, negtest(4));
%OptimizeFunctionOnNextCall(negtest);
negtest(4);