runtime: check pointer equality in arm cmpbody
Updates #11336
Follow the lead of amd64 do a pointer equality check
before comparing string/byte contents on arm.
BenchmarkCompareBytesEqual-4 208 211 +1.44%
BenchmarkCompareBytesToNil-4 83.6 81.8 -2.15%
BenchmarkCompareBytesEmpty-4 80.2 75.2 -6.23%
BenchmarkCompareBytesIdentical-4 208 75.2 -63.85%
BenchmarkCompareBytesSameLength-4 126 128 +1.59%
BenchmarkCompareBytesDifferentLength-4 128 130 +1.56%
BenchmarkCompareBytesBigUnaligned-4
14192804 14060971 -0.93%
BenchmarkCompareBytesBig-4
12277313 12128193 -1.21%
BenchmarkCompareBytesBigIdentical-4
9385046 78.5 -100.00%
Change-Id: I5b24620018688c5fe04b6ff6743a24c4ce225788
Reviewed-on: https://go-review.googlesource.com/13881
Reviewed-by: Keith Randall <khr@golang.org>