Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 1 | // Copyright 2014 the V8 project authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | // Flags: --allow-natives-syntax |
| 6 | |
| 7 | // Monkey-patch Float32Array. |
| 8 | Float32Array = function(x) { this[0] = 0; }; |
| 9 | |
| 10 | assertTrue(isNaN(Math.fround(NaN))); |
| 11 | assertTrue(isNaN(Math.fround(function() {}))); |
| 12 | assertTrue(isNaN(Math.fround({ toString: function() { return NaN; } }))); |
| 13 | assertTrue(isNaN(Math.fround({ valueOf: function() { return "abc"; } }))); |
| 14 | assertTrue(isNaN(Math.fround(NaN))); |
| 15 | assertTrue(isNaN(Math.fround(function() {}))); |
| 16 | assertTrue(isNaN(Math.fround({ toString: function() { return NaN; } }))); |
| 17 | assertTrue(isNaN(Math.fround({ valueOf: function() { return "abc"; } }))); |
| 18 | |
| 19 | function unopt(x) { return Math.fround(x); } |
| 20 | function opt(y) { return Math.fround(y); } |
| 21 | |
| 22 | opt(0.1); |
| 23 | opt(0.1); |
| 24 | unopt(0.1); |
| 25 | %NeverOptimizeFunction(unopt); |
| 26 | %OptimizeFunctionOnNextCall(opt); |
| 27 | |
| 28 | function test(f) { |
| 29 | assertEquals("Infinity", String(1/f(0))); |
| 30 | assertEquals("-Infinity", String(1/f(-0))); |
| 31 | assertEquals("Infinity", String(f(Infinity))); |
| 32 | assertEquals("-Infinity", String(f(-Infinity))); |
| 33 | assertEquals("Infinity", String(f(1E200))); |
| 34 | assertEquals("-Infinity", String(f(-1E200))); |
| 35 | assertEquals("Infinity", String(1/f(1E-300))); |
| 36 | assertEquals("-Infinity", String(1/f(-1E-300))); |
| 37 | } |
| 38 | |
| 39 | test(opt); |
| 40 | test(unopt); |
| 41 | |
| 42 | mantissa_23_shift = Math.pow(2, -23); |
| 43 | mantissa_29_shift = Math.pow(2, -23-29); |
| 44 | |
| 45 | // Javascript implementation of IEEE 754 to test double to single conversion. |
| 46 | function ieee754float(sign_bit, |
| 47 | exponent_bits, |
| 48 | mantissa_23_bits, |
| 49 | mantissa_29_bits) { |
| 50 | this.sign_bit = sign_bit & 1; |
| 51 | this.exponent_bits = exponent_bits & ((1 << 11) - 1); |
| 52 | this.mantissa_23_bits = mantissa_23_bits & ((1 << 23) - 1); |
| 53 | this.mantissa_29_bits = mantissa_29_bits & ((1 << 29) - 1); |
| 54 | } |
| 55 | |
| 56 | ieee754float.prototype.returnSpecial = function() { |
| 57 | if (mantissa_23_bits == 0 && mantissa_29_bits == 0) return sign * Infinity; |
| 58 | return NaN; |
| 59 | } |
| 60 | |
| 61 | ieee754float.prototype.toDouble = function() { |
| 62 | var sign = this.sign_bit ? -1 : 1; |
| 63 | var exponent = this.exponent_bits - 1023; |
| 64 | if (exponent == -1023) returnSpecial(); |
| 65 | var mantissa = 1 + this.mantissa_23_bits * mantissa_23_shift + |
| 66 | this.mantissa_29_bits * mantissa_29_shift; |
| 67 | return sign * Math.pow(2, exponent) * mantissa; |
| 68 | } |
| 69 | |
| 70 | ieee754float.prototype.toSingle = function() { |
| 71 | var sign = this.sign_bit ? -1 : 1; |
| 72 | var exponent = this.exponent_bits - 1023; |
| 73 | if (exponent == -1023) returnSpecial(); |
| 74 | if (exponent > 127) return sign * Infinity; |
| 75 | if (exponent < -126) return this.toSingleSubnormal(sign, exponent); |
| 76 | var round = this.mantissa_29_bits >> 28; |
| 77 | var mantissa = 1 + (this.mantissa_23_bits + round) * mantissa_23_shift; |
| 78 | return sign * Math.pow(2, exponent) * mantissa; |
| 79 | } |
| 80 | |
| 81 | ieee754float.prototype.toSingleSubnormal = function(sign, exponent) { |
| 82 | var shift = -126 - exponent; |
| 83 | if (shift > 24) return sign * 0; |
| 84 | var round_mask = 1 << (shift - 1); |
| 85 | var mantissa_23_bits = this.mantissa_23_bits + (1 << 23); |
| 86 | var round = ((mantissa_23_bits & round_mask) != 0) | 0; |
| 87 | if (round) { // Round to even if tied. |
| 88 | var tied_mask = round_mask - 1; |
| 89 | var result_last_bit_mask = 1 << shift; |
| 90 | var tied = this.mantissa_29_bits == 0 && |
| 91 | (mantissa_23_bits & tied_mask ) == 0; |
| 92 | var result_already_even = (mantissa_23_bits & result_last_bit_mask) == 0; |
| 93 | if (tied && result_already_even) round = 0; |
| 94 | } |
| 95 | mantissa_23_bits >>= shift; |
| 96 | var mantissa = (mantissa_23_bits + round) * mantissa_23_shift; |
| 97 | return sign * Math.pow(2, -126) * mantissa; |
| 98 | } |
| 99 | |
| 100 | |
| 101 | var pi = new ieee754float(0, 0x400, 0x490fda, 0x14442d18); |
| 102 | assertEquals(pi.toSingle(), opt(pi.toDouble())); |
| 103 | assertEquals(pi.toSingle(), unopt(pi.toDouble())); |
| 104 | |
| 105 | |
| 106 | function fuzz_mantissa(sign, exp, m1inc, m2inc) { |
| 107 | for (var m1 = 0; m1 < (1 << 23); m1 += m1inc) { |
| 108 | for (var m2 = 0; m2 < (1 << 29); m2 += m2inc) { |
| 109 | var float = new ieee754float(sign, exp, m1, m2); |
| 110 | assertEquals(float.toSingle(), unopt(float.toDouble())); |
| 111 | assertEquals(float.toSingle(), opt(float.toDouble())); |
| 112 | } |
| 113 | } |
| 114 | } |
| 115 | |
| 116 | for (var sign = 0; sign < 2; sign++) { |
| 117 | for (var exp = 1024 - 170; exp < 1024 + 170; exp++) { |
| 118 | fuzz_mantissa(sign, exp, 1337 * exp - sign, 127913 * exp - sign); |
| 119 | } |
| 120 | } |