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8209171: Simplify Java implementation of Integer/Long.numberOfTrailingZeros()

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Co-authored-by: Martin Buchholz <martinrb@google.com>
Reviewed-by: martin
This commit is contained in:
Ivan Gerasimov 2018-08-23 12:09:46 -07:00
parent acaf155de7
commit ffa4cfe355
2 changed files with 12 additions and 19 deletions
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13
src/java.base/share/classes/java/lang/Long.java
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@ -1782,16 +1782,9 @@ public final class Long extends Number implements Comparable<Long> {
*/
@HotSpotIntrinsicCandidate
public static int numberOfTrailingZeros(long i) {
// HD, Figure 5-14
int x, y;
if (i == 0) return 64;
int n = 63;
y = (int)i; if (y != 0) { n = n -32; x = y; } else x = (int)(i>>>32);
y = x <<16; if (y != 0) { n = n -16; x = y; }
y = x << 8; if (y != 0) { n = n - 8; x = y; }
y = x << 4; if (y != 0) { n = n - 4; x = y; }
y = x << 2; if (y != 0) { n = n - 2; x = y; }
return n - ((x << 1) >>> 31);
int x = (int)i;
return x == 0 ? 32 + Integer.numberOfTrailingZeros((int)(i >>> 32))
: Integer.numberOfTrailingZeros(x);
}
/**