runtime: check pointer equality in arm64 cmpbody
Updates #11336
Follow the lead of amd64 by doing a pointer equality check
before comparing string/byte contents on arm64.
BenchmarkCompareBytesEqual-8 25.8 26.3 +1.94%
BenchmarkCompareBytesToNil-8 9.59 9.59 +0.00%
BenchmarkCompareBytesEmpty-8 9.59 9.17 -4.38%
BenchmarkCompareBytesIdentical-8 26.3 9.17 -65.13%
BenchmarkCompareBytesSameLength-8 16.3 16.3 +0.00%
BenchmarkCompareBytesDifferentLength-8 16.3 16.3 +0.00%
BenchmarkCompareBytesBigUnaligned-8
1132038 1131409 -0.06%
BenchmarkCompareBytesBig-8
1126758 1128470 +0.15%
BenchmarkCompareBytesBigIdentical-8
1084366 9.17 -100.00%
Change-Id: Id7125c31957eff1ddb78897d4511bd50e79af3f7
Reviewed-on: https://go-review.googlesource.com/13885
Reviewed-by: Keith Randall <khr@golang.org>