d98c51809d
For the SubFromLen64 codegen test case to work as intended, we need
to fold c-(-(x-d)) into x+(c-d).
Still, some instances of LeadingZeros are not optimized into single
CLZ instructions right now (actually, the LeadingZeros micro-benchmarks
are currently still compiled with redundant adds/subs of 64, due to
interference of loop optimizations before lowering), but perf numbers
indicate it's not that bad after all.
Micro-benchmark results on Loongson 3A5000 and 3A6000:
goos: linux
goarch: loong64
pkg: math/bits
cpu: Loongson-3A5000 @ 2500.00MHz
| bench.old | bench.new |
| sec/op | sec/op vs base |
LeadingZeros 3.660n ± 0% 1.348n ± 0% -63.17% (p=0.000 n=20)
LeadingZeros8 1.777n ± 0% 1.767n ± 0% -0.56% (p=0.000 n=20)
LeadingZeros16 2.816n ± 0% 1.770n ± 0% -37.14% (p=0.000 n=20)
LeadingZeros32 5.293n ± 1% 1.683n ± 0% -68.21% (p=0.000 n=20)
LeadingZeros64 3.622n ± 0% 1.349n ± 0% -62.76% (p=0.000 n=20)
geomean 3.229n 1.571n -51.35%
goos: linux
goarch: loong64
pkg: math/bits
cpu: Loongson-3A6000 @ 2500.00MHz
| bench.old | bench.new |
| sec/op | sec/op vs base |
LeadingZeros 2.410n ± 0% 1.103n ± 1% -54.23% (p=0.000 n=20)
LeadingZeros8 1.236n ± 0% 1.501n ± 0% +21.44% (p=0.000 n=20)
LeadingZeros16 2.106n ± 0% 1.501n ± 0% -28.73% (p=0.000 n=20)
LeadingZeros32 2.860n ± 0% 1.324n ± 0% -53.72% (p=0.000 n=20)
LeadingZeros64 2.6135n ± 0% 0.9509n ± 0% -63.62% (p=0.000 n=20)
geomean 2.159n 1.256n -41.81%
Updates #59120
This patch is a copy of CL 483356.
Co-authored-by: WANG Xuerui <git@xen0n.name>
Change-Id: Iee81a17f7da06d77a427e73dfcc016f2b15ae556
Reviewed-on: https://go-review.googlesource.com/c/go/+/624575
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
Reviewed-by: abner chenc <chenguoqi@loongson.cn>
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| api | ||
| doc | ||
| lib | ||
| misc | ||
| src | ||
| test | ||
| .gitattributes | ||
| .gitignore | ||
| codereview.cfg | ||
| CONTRIBUTING.md | ||
| go.env | ||
| LICENSE | ||
| PATENTS | ||
| README.md | ||
| SECURITY.md | ||
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