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 } 121
