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cmd/compile: use cheaper implementation of oneBit

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Updates #38547

file    before    after     Δ       %       
compile 19678112  19669808  -8304   -0.042% 
total   113143160 113134856 -8304   -0.007% 

Change-Id: I5f8afe17401dbdb7c7b3d66d95fe40821c499a92
Reviewed-on: https://go-review.googlesource.com/c/go/+/229127
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Josh Bleecher Snyder 2020-04-20 15:40:38 -07:00
parent 50b11318fe
commit 066c47ca5f
1 changed files with 5 additions and 5 deletions
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10
src/cmd/compile/internal/ssa/rewrite.go
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@ -395,11 +395,11 @@ func ntz32(x int32) int { return bits.TrailingZeros32(uint32(x)) }
func ntz16(x int16) int { return bits.TrailingZeros16(uint16(x)) } func ntz16(x int16) int { return bits.TrailingZeros16(uint16(x)) }
func ntz8(x int8) int { return bits.TrailingZeros8(uint8(x)) } func ntz8(x int8) int { return bits.TrailingZeros8(uint8(x)) }
func oneBit(x int64) bool { return bits.OnesCount64(uint64(x)) == 1 } func oneBit(x int64) bool { return x&(x-1) == 0 }
func oneBit8(x int8) bool { return bits.OnesCount8(uint8(x)) == 1 } func oneBit8(x int8) bool { return x&(x-1) == 0 }
func oneBit16(x int16) bool { return bits.OnesCount16(uint16(x)) == 1 } func oneBit16(x int16) bool { return x&(x-1) == 0 }
func oneBit32(x int32) bool { return bits.OnesCount32(uint32(x)) == 1 } func oneBit32(x int32) bool { return x&(x-1) == 0 }
func oneBit64(x int64) bool { return bits.OnesCount64(uint64(x)) == 1 } func oneBit64(x int64) bool { return x&(x-1) == 0 }
// nlo returns the number of leading ones. // nlo returns the number of leading ones.
func nlo(x int64) int64 { func nlo(x int64) int64 {