a8a02a51f1
R=svenpanne@chromium.org BUG=v8:3469 LOG=N Review URL: https://codereview.chromium.org/425943002 git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22665 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
121 lines
4.2 KiB
JavaScript
121 lines
4.2 KiB
JavaScript
// Copyright 2014 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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// Monkey-patch Float32Array.
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Float32Array = function(x) { this[0] = 0; };
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assertTrue(isNaN(Math.fround(NaN)));
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assertTrue(isNaN(Math.fround(function() {})));
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assertTrue(isNaN(Math.fround({ toString: function() { return NaN; } })));
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assertTrue(isNaN(Math.fround({ valueOf: function() { return "abc"; } })));
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assertTrue(isNaN(Math.fround(NaN)));
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assertTrue(isNaN(Math.fround(function() {})));
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assertTrue(isNaN(Math.fround({ toString: function() { return NaN; } })));
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assertTrue(isNaN(Math.fround({ valueOf: function() { return "abc"; } })));
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function unopt(x) { return Math.fround(x); }
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function opt(y) { return Math.fround(y); }
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opt(0.1);
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opt(0.1);
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unopt(0.1);
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%NeverOptimizeFunction(unopt);
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%OptimizeFunctionOnNextCall(opt);
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function test(f) {
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assertEquals("Infinity", String(1/f(0)));
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assertEquals("-Infinity", String(1/f(-0)));
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assertEquals("Infinity", String(f(Infinity)));
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assertEquals("-Infinity", String(f(-Infinity)));
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assertEquals("Infinity", String(f(1E200)));
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assertEquals("-Infinity", String(f(-1E200)));
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assertEquals("Infinity", String(1/f(1E-300)));
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assertEquals("-Infinity", String(1/f(-1E-300)));
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}
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test(opt);
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test(unopt);
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mantissa_23_shift = Math.pow(2, -23);
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mantissa_29_shift = Math.pow(2, -23-29);
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// Javascript implementation of IEEE 754 to test double to single conversion.
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function ieee754float(sign_bit,
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exponent_bits,
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mantissa_23_bits,
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mantissa_29_bits) {
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this.sign_bit = sign_bit & 1;
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this.exponent_bits = exponent_bits & ((1 << 11) - 1);
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this.mantissa_23_bits = mantissa_23_bits & ((1 << 23) - 1);
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this.mantissa_29_bits = mantissa_29_bits & ((1 << 29) - 1);
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}
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ieee754float.prototype.returnSpecial = function() {
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if (mantissa_23_bits == 0 && mantissa_29_bits == 0) return sign * Infinity;
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return NaN;
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}
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ieee754float.prototype.toDouble = function() {
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var sign = this.sign_bit ? -1 : 1;
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var exponent = this.exponent_bits - 1023;
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if (exponent == -1023) returnSpecial();
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var mantissa = 1 + this.mantissa_23_bits * mantissa_23_shift +
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this.mantissa_29_bits * mantissa_29_shift;
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return sign * Math.pow(2, exponent) * mantissa;
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}
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ieee754float.prototype.toSingle = function() {
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var sign = this.sign_bit ? -1 : 1;
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var exponent = this.exponent_bits - 1023;
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if (exponent == -1023) returnSpecial();
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if (exponent > 127) return sign * Infinity;
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if (exponent < -126) return this.toSingleSubnormal(sign, exponent);
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var round = this.mantissa_29_bits >> 28;
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var mantissa = 1 + (this.mantissa_23_bits + round) * mantissa_23_shift;
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return sign * Math.pow(2, exponent) * mantissa;
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}
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ieee754float.prototype.toSingleSubnormal = function(sign, exponent) {
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var shift = -126 - exponent;
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if (shift > 24) return sign * 0;
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var round_mask = 1 << (shift - 1);
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var mantissa_23_bits = this.mantissa_23_bits + (1 << 23);
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var round = ((mantissa_23_bits & round_mask) != 0) | 0;
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if (round) { // Round to even if tied.
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var tied_mask = round_mask - 1;
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var result_last_bit_mask = 1 << shift;
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var tied = this.mantissa_29_bits == 0 &&
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(mantissa_23_bits & tied_mask ) == 0;
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var result_already_even = (mantissa_23_bits & result_last_bit_mask) == 0;
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if (tied && result_already_even) round = 0;
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}
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mantissa_23_bits >>= shift;
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var mantissa = (mantissa_23_bits + round) * mantissa_23_shift;
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return sign * Math.pow(2, -126) * mantissa;
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}
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var pi = new ieee754float(0, 0x400, 0x490fda, 0x14442d18);
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assertEquals(pi.toSingle(), opt(pi.toDouble()));
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assertEquals(pi.toSingle(), unopt(pi.toDouble()));
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function fuzz_mantissa(sign, exp, m1inc, m2inc) {
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for (var m1 = 0; m1 < (1 << 23); m1 += m1inc) {
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for (var m2 = 0; m2 < (1 << 29); m2 += m2inc) {
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var float = new ieee754float(sign, exp, m1, m2);
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assertEquals(float.toSingle(), unopt(float.toDouble()));
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assertEquals(float.toSingle(), opt(float.toDouble()));
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}
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}
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}
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for (var sign = 0; sign < 2; sign++) {
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for (var exp = 1024 - 170; exp < 1024 + 170; exp++) {
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fuzz_mantissa(sign, exp, 1337 * exp - sign, 127913 * exp - sign);
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}
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}
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