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Update dart2js/ddc int.bitLength

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1. Make bitLength work on very large values. This fixes problems with
BigInt.from on large values.

2. Restructure to allow Math.clz32 to be used once dart2js no longer
supporst IE11.

Change-Id: I255f030ff3b3630cdee63502d11a8b6630a4f008
Reviewed-on: https://dart-review.googlesource.com/41960
Reviewed-by: Sigmund Cherem <sigmund@google.com>
Reviewed-by: Vijay Menon <vsm@google.com>
This commit is contained in:
Stephen Adams 2018-02-16 22:26:35 +00:00
parent 188697d6e1
commit e1cfc35572
2 changed files with 22 additions and 9 deletions
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13
pkg/dev_compiler/tool/input_sdk/private/js_number.dart
View file

@ -384,11 +384,18 @@ class JSNumber extends Interceptor implements int, double {
@notNull
int get bitLength {
int nonneg = this < 0 ? -this - 1 : this;
if (nonneg >= 0x100000000) {
int wordBits = 32;
while (nonneg >= 0x100000000) {
nonneg = nonneg ~/ 0x100000000;
return _bitCount(_spread(nonneg)) + 32;
wordBits += 32;
}
return _bitCount(_spread(nonneg));
return wordBits - _clz32(nonneg);
}
@notNull
static int _clz32(@notNull int uint32) {
// TODO(sra): Use `Math.clz32(uint32)` (not available on IE11).
return 32 - _bitCount(_spread(uint32));
}
// Returns pow(this, e) % m.

18
sdk/lib/_internal/js_runtime/lib/js_number.dart
View file

@ -433,11 +433,17 @@ class JSInt extends JSNumber implements int, double {
int get bitLength {
int nonneg = this < 0 ? -this - 1 : this;
if (nonneg >= 0x100000000) {
int wordBits = 32;
while (nonneg >= 0x100000000) {
nonneg = nonneg ~/ 0x100000000;
return _bitCount(_spread(nonneg)) + 32;
wordBits += 32;
}
return _bitCount(_spread(nonneg));
return wordBits - _clz32(nonneg);
}
static int _clz32(int uint32) {
// TODO(sra): Use `Math.clz32(uint32)` (not available on IE11).
return 32 - _bitCount(_spread(uint32));
}
// Returns pow(this, e) % m.
@ -592,9 +598,9 @@ class JSInt extends JSNumber implements int, double {
return (i & 0x0000003F);
}
static _shru(int value, int shift) => JS('int', '# >>> #', value, shift);
static _shrs(int value, int shift) => JS('int', '# >> #', value, shift);
static _ors(int a, int b) => JS('int', '# | #', a, b);
static int _shru(int value, int shift) => JS('int', '# >>> #', value, shift);
static int _shrs(int value, int shift) => JS('int', '# >> #', value, shift);
static int _ors(int a, int b) => JS('int', '# | #', a, b);
// Assumes i is <= 32-bit
static int _spread(int i) {