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cmd/compile: intrinsics for math/bits.OnesCount

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Popcount instructions on amd64 are not guaranteed to be
present, so we must guard their call.  Rewrite rules can't
generate control flow at the moment, so the intrinsifier
needs to generate that code.

name           old time/op  new time/op  delta
OnesCount-8    2.47ns ± 5%  1.04ns ± 2%  -57.70%  (p=0.000 n=10+10)
OnesCount16-8  1.05ns ± 1%  0.78ns ± 0%  -25.56%    (p=0.000 n=9+8)
OnesCount32-8  1.63ns ± 5%  1.04ns ± 2%  -35.96%  (p=0.000 n=10+10)
OnesCount64-8  2.45ns ± 0%  1.04ns ± 1%  -57.55%   (p=0.000 n=6+10)

Update #18616

Change-Id: I4aff2cc9aa93787898d7b22055fe272a7cf95673
Reviewed-on: https://go-review.googlesource.com/38320
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Keith Randall 2017-03-16 21:33:03 -07:00 • committed by Keith Randall
parent 59f6549d1c
commit 5cadc91b3c
10 changed files with 228 additions and 0 deletions
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5
src/cmd/compile/internal/ssa/gen/genericOps.go
View file

@ -250,6 +250,11 @@ var genericOps = []opData{
{name: "BitRev32", argLength: 1}, // Reverse the bits in arg[0]
{name: "BitRev64", argLength: 1}, // Reverse the bits in arg[0]
{name: "PopCount8", argLength: 1}, // Count bits in arg[0]
{name: "PopCount16", argLength: 1}, // Count bits in arg[0]
{name: "PopCount32", argLength: 1}, // Count bits in arg[0]
{name: "PopCount64", argLength: 1}, // Count bits in arg[0]
{name: "Sqrt", argLength: 1}, // sqrt(arg0), float64 only
// Data movement, max argument length for Phi is indefinite so just pick