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cmd/compile: store combine not working on ppc64 and arm64 with global variables #24242
While migrating the code generation tests for load/store combiners to to the top-level testsuite (fad31e5), I had to disable some tests for arm64 and ppc64le because it looks like that store combining is failing in some situations.
It looks like the bug is related to the fact that the store is made from a global variable rather than a local variable (as was being previously tested).
I noticed this regression in combining little endian stores while testing my current change for combining loads and stores in big endian order on ppc64le. I have a fix that I was going to include with the big endian change, but could make it separate if that is preferred.
CL 74410 added rules to combine consecutive byte loads and stores when the byte order was little endian for ppc64le. This is the corresponding change for bytes that are in big endian order. These rules are all intended for a little endian target arch. This adds new testcases in test/codegen/memcombine.go Fixes #22496 Updates #24242 Benchmark improvement for encoding/binary: name old time/op new time/op delta ReadSlice1000Int32s-16 11.0µs ± 0% 9.0µs ± 0% -17.47% (p=0.029 n=4+4) ReadStruct-16 2.47µs ± 1% 2.48µs ± 0% +0.67% (p=0.114 n=4+4) ReadInts-16 642ns ± 1% 630ns ± 1% -2.02% (p=0.029 n=4+4) WriteInts-16 654ns ± 0% 653ns ± 1% -0.08% (p=0.629 n=4+4) WriteSlice1000Int32s-16 8.75µs ± 0% 8.20µs ± 0% -6.19% (p=0.029 n=4+4) PutUint16-16 1.16ns ± 0% 0.93ns ± 0% -19.83% (p=0.029 n=4+4) PutUint32-16 1.16ns ± 0% 0.93ns ± 0% -19.83% (p=0.029 n=4+4) PutUint64-16 1.85ns ± 0% 0.93ns ± 0% -49.73% (p=0.029 n=4+4) LittleEndianPutUint16-16 1.03ns ± 0% 0.93ns ± 0% -9.71% (p=0.029 n=4+4) LittleEndianPutUint32-16 0.93ns ± 0% 0.93ns ± 0% ~ (all equal) LittleEndianPutUint64-16 0.93ns ± 0% 0.93ns ± 0% ~ (all equal) PutUvarint32-16 43.0ns ± 0% 43.1ns ± 0% +0.12% (p=0.429 n=4+4) PutUvarint64-16 174ns ± 0% 175ns ± 0% +0.29% (p=0.429 n=4+4) Updates made to functions in gcm.go to enable their matching. An existing testcase prevents these functions from being replaced by those in encoding/binary due to import dependencies. Change-Id: Idb3bd1e6e7b12d86cd828fb29cb095848a3e485a Reviewed-on: https://go-review.googlesource.com/98136 Run-TryBot: Lynn Boger <email@example.com> TryBot-Result: Gobot Gobot <firstname.lastname@example.org> Reviewed-by: Keith Randall <email@example.com>