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Int64 improvements

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1. Avoid test for JavaScript vs VM
2. strengthen & and | masking to help infer uint31 types in tests

R=cbracken@google.com

Review URL: https://codereview.chromium.org/1520773002 .
This commit is contained in:
Stephen Adams 2015-12-14 13:50:11 -08:00
parent a1ed9c6d17
commit 231de7d3c2
2 changed files with 16 additions and 49 deletions
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63
pkg/fixnum/lib/src/int64.dart
View file

@ -104,7 +104,7 @@ class Int64 implements IntX {
if (negative) return _negate(d0, d1, d2);
return new Int64._bits(d0, d1, d2);
return Int64._masked(d0, d1, d2);
}
/**
@ -131,18 +131,13 @@ class Int64 implements IntX {
negative = true;
value = -value - 1;
}
if (_haveBigInts) {
v0 = _MASK & value;
v1 = _MASK & (value >> _BITS);
v2 = _MASK2 & (value >> _BITS01);
} else {
// Avoid using bitwise operations that coerce their input to 32 bits.
v2 = value ~/ 17592186044416; // 2^44
value -= v2 * 17592186044416;
v1 = value ~/ 4194304; // 2^22
value -= v1 * 4194304;
v0 = value;
}
// Avoid using bitwise operations that in JavaScript coerce their input to
// 32 bits.
v2 = value ~/ 17592186044416; // 2^44
value -= v2 * 17592186044416;
v1 = value ~/ 4194304; // 2^22
value -= v1 * 4194304;
v0 = value;
if (negative) {
v0 = ~v0;
@ -202,7 +197,7 @@ class Int64 implements IntX {
int d0 = _MASK & bottom;
int d1 = ((0xfff & top) << 10) | (0x3ff & (bottom >> _BITS));
int d2 = _MASK2 & (top >> 12);
return new Int64._bits(d0, d1, d2);
return Int64._masked(d0, d1, d2);
}
// Returns the [Int64] representation of the specified value. Throws
@ -325,7 +320,7 @@ class Int64 implements IntX {
int a0 = _l & o._l;
int a1 = _m & o._m;
int a2 = _h & o._h;
return new Int64._bits(a0, a1, a2);
return Int64._masked(a0, a1, a2);
}
Int64 operator |(other) {
@ -333,7 +328,7 @@ class Int64 implements IntX {
int a0 = _l | o._l;
int a1 = _m | o._m;
int a2 = _h | o._h;
return new Int64._bits(a0, a1, a2);
return Int64._masked(a0, a1, a2);
}
Int64 operator ^(other) {
@ -629,23 +624,15 @@ class Int64 implements IntX {
int l = _l;
int m = _m;
int h = _h;
bool negative = false;
// In the sum we add least significant to most significant so that in
// JavaScript double arithmetic rounding occurs on only the last addition.
if ((_h & _SIGN_BIT_MASK) != 0) {
l = _MASK & ~_l;
m = _MASK & ~_m;
h = _MASK2 & ~_h;
negative = true;
}
if (_haveBigInts) {
int result = (h << _BITS01) | (m << _BITS) | l;
return negative ? -result - 1 : result;
return -((1 + l) + (4194304 * m) + (17592186044416 * h));
} else {
if (negative) {
return -((l + 1) + (m * 4194304) + (h * 17592186044416));
} else {
return (l + (m * 4194304)) + (h * 17592186044416);
}
return l + (4194304 * m) + (17592186044416 * h);
}
}
@ -671,7 +658,6 @@ class Int64 implements IntX {
if (isZero) return "0";
Int64 x = this;
String hexStr = "";
Int64 digit_f = new Int64(0xf);
while (!x.isZero) {
int digit = x._l & 0xf;
hexStr = "${_hexDigit(digit)}$hexStr";
@ -843,27 +829,8 @@ class Int64 implements IntX {
return _sub(0, 0, 0, b0, b1, b2);
}
// Determine whether the platform supports ints greater than 2^53
// without loss of precision.
static bool _haveBigIntsCached = null;
static bool get _haveBigInts {
if (_haveBigIntsCached == null) {
var x = 9007199254740992;
// Defeat compile-time constant folding.
if (2 + 2 != 4) {
x = 0;
}
var y = x + 1;
var same = y == x;
_haveBigIntsCached = !same;
}
return _haveBigIntsCached;
}
String _hexDigit(int digit) => "0123456789ABCDEF"[digit];
// Work around dart2js bugs with negative arguments to '>>' operator.
static int _shiftRight(int x, int n) {
if (x >= 0) {

2
pkg/fixnum/pubspec.yaml
View file

@ -1,5 +1,5 @@
name: fixnum
version: 0.10.2
version: 0.10.3
author: Dart Team <misc@dartlang.org>
description: Library for 32- and 64-bit fixed size integers.
homepage: http://www.dartlang.org