From 9ffe004ae4e7015f0e5881f56539fe35465cdf87 Mon Sep 17 00:00:00 2001 From: "yangguo@chromium.org" Date: Tue, 18 Feb 2014 10:43:06 +0000 Subject: [PATCH] Harmony: implement Math.fround. R=jarin@chromium.org BUG=v8:2938 LOG=N Review URL: https://codereview.chromium.org/169513002 git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19433 ce2b1a6d-e550-0410-aec6-3dcde31c8c00 --- src/harmony-math.js | 15 ++++-- src/runtime.cc | 10 ++++ src/runtime.h | 1 + test/mjsunit/harmony/math-fround.js | 99 +++++++++++++++++++++++++++++++++++++ 4 files changed, 121 insertions(+), 4 deletions(-) create mode 100644 test/mjsunit/harmony/math-fround.js diff --git a/src/harmony-math.js b/src/harmony-math.js index ee426ef..4265f17 100644 --- a/src/harmony-math.js +++ b/src/harmony-math.js @@ -109,19 +109,19 @@ function MathAtanh(x) { } -//ES6 draft 09-27-13, section 20.2.2.21. +// ES6 draft 09-27-13, section 20.2.2.21. function MathLog10(x) { return MathLog(x) * 0.434294481903251828; // log10(x) = log(x)/log(10). } -//ES6 draft 09-27-13, section 20.2.2.22. +// ES6 draft 09-27-13, section 20.2.2.22. function MathLog2(x) { return MathLog(x) * 1.442695040888963407; // log2(x) = log(x)/log(2). } -//ES6 draft 09-27-13, section 20.2.2.17. +// ES6 draft 09-27-13, section 20.2.2.17. function MathHypot(x, y) { // Function length is 2. // We may want to introduce fast paths for two arguments and when // normalization to avoid overflow is not necessary. For now, we @@ -154,6 +154,12 @@ function MathHypot(x, y) { // Function length is 2. } +// ES6 draft 09-27-13, section 20.2.2.16. +function MathFround(x) { + return %Math_fround(TO_NUMBER_INLINE(x)); +} + + function ExtendMath() { %CheckIsBootstrapping(); @@ -169,7 +175,8 @@ function ExtendMath() { "atanh", MathAtanh, "log10", MathLog10, "log2", MathLog2, - "hypot", MathHypot + "hypot", MathHypot, + "fround", MathFround )); } diff --git a/src/runtime.cc b/src/runtime.cc index 958675a..48c4ef0 100644 --- a/src/runtime.cc +++ b/src/runtime.cc @@ -7829,6 +7829,16 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_Math_sqrt) { } +RUNTIME_FUNCTION(MaybeObject*, Runtime_Math_fround) { + SealHandleScope shs(isolate); + ASSERT(args.length() == 1); + + CONVERT_DOUBLE_ARG_CHECKED(x, 0); + float xf = static_cast(x); + return isolate->heap()->AllocateHeapNumber(xf); +} + + RUNTIME_FUNCTION(MaybeObject*, Runtime_DateMakeDay) { SealHandleScope shs(isolate); ASSERT(args.length() == 2); diff --git a/src/runtime.h b/src/runtime.h index ae8cc3d..95f41bb 100644 --- a/src/runtime.h +++ b/src/runtime.h @@ -185,6 +185,7 @@ namespace internal { F(Math_pow_cfunction, 2, 1) \ F(RoundNumber, 1, 1) \ F(Math_sqrt, 1, 1) \ + F(Math_fround, 1, 1) \ \ /* Regular expressions */ \ F(RegExpCompile, 3, 1) \ diff --git a/test/mjsunit/harmony/math-fround.js b/test/mjsunit/harmony/math-fround.js new file mode 100644 index 0000000..ea432ea --- /dev/null +++ b/test/mjsunit/harmony/math-fround.js @@ -0,0 +1,99 @@ +// Copyright 2014 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: --harmony-maths + +// Monkey-patch Float32Array. +Float32Array = function(x) { this[0] = 0; }; + +assertTrue(isNaN(Math.fround(NaN))); +assertTrue(isNaN(Math.fround(function() {}))); +assertTrue(isNaN(Math.fround({ toString: function() { return NaN; } }))); +assertTrue(isNaN(Math.fround({ valueOf: function() { return "abc"; } }))); +assertEquals("Infinity", String(1/Math.fround(0))); +assertEquals("-Infinity", String(1/Math.fround(-0))); +assertEquals("Infinity", String(Math.fround(Infinity))); +assertEquals("-Infinity", String(Math.fround(-Infinity))); + +assertEquals("Infinity", String(Math.fround(1E200))); +assertEquals("-Infinity", String(Math.fround(-1E200))); +assertEquals("Infinity", String(1/Math.fround(1E-300))); +assertEquals("-Infinity", String(1/Math.fround(-1E-300))); + +mantissa_23_shift = Math.pow(2, -23); +mantissa_29_shift = Math.pow(2, -23-29); + +// Javascript implementation of IEEE 754 to test double to single conversion. +function ieee754float(sign_bit, + exponent_bits, + mantissa_23_bits, + mantissa_29_bits) { + this.sign_bit = sign_bit & 1; + this.exponent_bits = exponent_bits & ((1 << 11) - 1); + this.mantissa_23_bits = mantissa_23_bits & ((1 << 23) - 1); + this.mantissa_29_bits = mantissa_29_bits & ((1 << 29) - 1); +} + +ieee754float.prototype.returnSpecial = function() { + if (mantissa_23_bits == 0 && mantissa_29_bits == 0) return sign * Infinity; + return NaN; +} + +ieee754float.prototype.toDouble = function() { + var sign = this.sign_bit ? -1 : 1; + var exponent = this.exponent_bits - 1023; + if (exponent == -1023) returnSpecial(); + var mantissa = 1 + this.mantissa_23_bits * mantissa_23_shift + + this.mantissa_29_bits * mantissa_29_shift; + return sign * Math.pow(2, exponent) * mantissa; +} + +ieee754float.prototype.toSingle = function() { + var sign = this.sign_bit ? -1 : 1; + var exponent = this.exponent_bits - 1023; + if (exponent == -1023) returnSpecial(); + if (exponent > 127) return sign * Infinity; + if (exponent < -126) return this.toSingleSubnormal(sign, exponent); + var round = this.mantissa_29_bits >> 28; + var mantissa = 1 + (this.mantissa_23_bits + round) * mantissa_23_shift; + return sign * Math.pow(2, exponent) * mantissa; +} + +ieee754float.prototype.toSingleSubnormal = function(sign, exponent) { + var shift = -126 - exponent; + if (shift > 24) return sign * 0; + var round_mask = 1 << (shift - 1); + var mantissa_23_bits = this.mantissa_23_bits + (1 << 23); + var round = ((mantissa_23_bits & round_mask) != 0) | 0; + if (round) { // Round to even if tied. + var tied_mask = round_mask - 1; + var result_last_bit_mask = 1 << shift; + var tied = this.mantissa_29_bits == 0 && + (mantissa_23_bits & tied_mask ) == 0; + var result_already_even = (mantissa_23_bits & result_last_bit_mask) == 0; + if (tied && result_already_even) round = 0; + } + mantissa_23_bits >>= shift; + var mantissa = (mantissa_23_bits + round) * mantissa_23_shift; + return sign * Math.pow(2, -126) * mantissa; +} + + +var pi = new ieee754float(0, 0x400, 0x490fda, 0x14442d18); +assertEquals(pi.toSingle(), Math.fround(pi.toDouble())); + +function fuzz_mantissa(sign, exp, m1inc, m2inc) { + for (var m1 = 0; m1 < (1 << 23); m1 += m1inc) { + for (var m2 = 0; m2 < (1 << 29); m2 += m2inc) { + var float = new ieee754float(sign, exp, m1, m2); + assertEquals(float.toSingle(), Math.fround(float.toDouble())); + } + } +} + +for (var sign = 0; sign < 2; sign++) { + for (var exp = 1024 - 170; exp < 1024 + 170; exp++) { + fuzz_mantissa(sign, exp, 1337 * exp - sign, 127913 * exp - sign); + } +} -- 2.7.4