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runtime: improve ppc64x memclr for tail bytes

This improves memclr for the last few bytes when
compiling for power9 or earlier.

Change-Id: I46940ebc7e98e27a2e48d4b319acb7d2106a6f29
Reviewed-on: https://go-review.googlesource.com/c/go/+/495035
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
Reviewed-by: Paul Murphy <murp@ibm.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
This commit is contained in:
Lynn Boger 2023-05-15 14:11:30 -05:00
parent 5534f04498
commit 470c6f6418

View File

@ -111,11 +111,21 @@ nozerolarge:
STXVL V0, R3, R7
RET
#else
MOVD R5, CTR // set up to clear tail bytes
zerotailloop:
MOVB R0, 0(R3) // clear single bytes
ADD $1, R3
BDNZ zerotailloop // dec ctr, br zerotailloop if ctr not 0
CMP R5, $4
BLT next2
MOVW R0, 0(R3)
ADD $4, R3
ADD $-4, R5
next2:
CMP R5, $2
BLT next1
MOVH R0, 0(R3)
ADD $2, R3
ADD $-2, R5
next1:
CMP R5, $0
BC 12, 2, LR // beqlr
MOVB R0, 0(R3)
RET
#endif