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* [glibc] x86: Use `testb` for FSRM check in memmove-vec-unaligned-erms
@ 2022-10-20 19:04 Noah Goldstein
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From: Noah Goldstein @ 2022-10-20 19:04 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=8775479804cfea2bbe4dcdf19d6589264c96d5fb
commit 8775479804cfea2bbe4dcdf19d6589264c96d5fb
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Wed Oct 19 19:13:38 2022 -0700
x86: Use `testb` for FSRM check in memmove-vec-unaligned-erms
`testb` saves a bit of code size is the imm-operand can be encoded
1-bytes.
Tested on x86-64.
Diff:
---
sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S b/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S
index 5b758cae5e..f6d7f3e88b 100644
--- a/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S
+++ b/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S
@@ -616,7 +616,11 @@ L(movsb):
jae L(large_memcpy_2x_check)
# if AVOID_SHORT_DISTANCE_REP_MOVSB || ALIGN_MOVSB
/* Only avoid short movsb if CPU has FSRM. */
+# if X86_STRING_CONTROL_AVOID_SHORT_DISTANCE_REP_MOVSB < 256
+ testb $X86_STRING_CONTROL_AVOID_SHORT_DISTANCE_REP_MOVSB, __x86_string_control(%rip)
+# else
testl $X86_STRING_CONTROL_AVOID_SHORT_DISTANCE_REP_MOVSB, __x86_string_control(%rip)
+# endif
jz L(skip_short_movsb_check)
# if AVOID_SHORT_DISTANCE_REP_MOVSB
/* Avoid "rep movsb" if RCX, the distance between source and
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2022-10-20 19:04 [glibc] x86: Use `testb` for FSRM check in memmove-vec-unaligned-erms Noah Goldstein
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