cmd/compile: intrinsify swissmap match calls with SIMD on amd64
Use similar SIMD operations to the ones used in Abseil. We still
using 8-slot groups (even though the XMM registers could handle 16-slot
groups) to keep the implementation simpler (no changes to the memory
layout of maps).
Still, the implementations of matchH2 and matchEmpty are shorter than
the portable version using standard arithmetic operations. They also
return a packed bitset, which avoids the need to shift in bitset.first.
That said, the packed bitset is a downside in cognitive complexity, as
we have to think about two different possible representations. This
doesn't leak out of the API, but we do need to intrinsify bitset to
switch to a compatible implementation.
The compiler's intrinsics don't support intrinsifying methods, so the
implementations move to free functions.
This makes operations between 0-3% faster on my machine. e.g.,
MapGetHit/impl=runtimeMap/t=Int64/len=6-12 12.34n ± 1% 11.42n ± 1% -7.46% (p=0.000 n=25)
MapGetHit/impl=runtimeMap/t=Int64/len=12-12 15.14n ± 2% 14.88n ± 1% -1.72% (p=0.009 n=25)
MapGetHit/impl=runtimeMap/t=Int64/len=18-12 15.04n ± 6% 14.66n ± 2% -2.53% (p=0.000 n=25)
MapGetHit/impl=runtimeMap/t=Int64/len=24-12 15.80n ± 1% 15.48n ± 3% ~ (p=0.444 n=25)
MapGetHit/impl=runtimeMap/t=Int64/len=30-12 15.55n ± 4% 14.77n ± 3% -5.02% (p=0.004 n=25)
MapGetHit/impl=runtimeMap/t=Int64/len=64-12 15.26n ± 1% 15.05n ± 1% ~ (p=0.055 n=25)
MapGetHit/impl=runtimeMap/t=Int64/len=128-12 15.34n ± 1% 15.02n ± 2% -2.09% (p=0.000 n=25)
MapGetHit/impl=runtimeMap/t=Int64/len=256-12 15.42n ± 1% 15.15n ± 1% -1.75% (p=0.001 n=25)
MapGetHit/impl=runtimeMap/t=Int64/len=512-12 15.48n ± 1% 15.18n ± 1% -1.94% (p=0.000 n=25)
MapGetHit/impl=runtimeMap/t=Int64/len=1024-12 17.38n ± 1% 17.05n ± 1% -1.90% (p=0.000 n=25)
MapGetHit/impl=runtimeMap/t=Int64/len=2048-12 17.96n ± 0% 17.59n ± 1% -2.06% (p=0.000 n=25)
MapGetHit/impl=runtimeMap/t=Int64/len=4096-12 18.36n ± 1% 18.18n ± 1% -0.98% (p=0.013 n=25)
MapGetHit/impl=runtimeMap/t=Int64/len=8192-12 18.75n ± 0% 18.31n ± 1% -2.35% (p=0.000 n=25)
MapGetHit/impl=runtimeMap/t=Int64/len=65536-12 26.25n ± 0% 25.95n ± 1% -1.14% (p=0.000 n=25)
MapGetHit/impl=runtimeMap/t=Int64/len=262144-12 44.24n ± 1% 44.06n ± 1% ~ (p=0.181 n=25)
MapGetHit/impl=runtimeMap/t=Int64/len=
1048576-12 85.02n ± 0% 85.35n ± 0% +0.39% (p=0.032 n=25)
MapGetHit/impl=runtimeMap/t=Int64/len=
4194304-12 98.87n ± 1% 98.85n ± 1% ~ (p=0.799 n=25)
For #54766.
Cq-Include-Trybots: luci.golang.try:gotip-linux-ppc64_power10,gotip-linux-amd64-goamd64v3
Change-Id: Ic1b852f02744404122cb3672900fd95f4625905e
Reviewed-on: https://go-review.googlesource.com/c/go/+/626277
Reviewed-by: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
Reviewed-by: Keith Randall <khr@google.com>