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GNU C Library master sources branch hjl/erms/hybrid updated. glibc-2.23-132-ge0ab62a
- From: hjl at sourceware dot org
- To: glibc-cvs at sourceware dot org
- Date: 26 Mar 2016 02:30:11 -0000
- Subject: GNU C Library master sources branch hjl/erms/hybrid updated. glibc-2.23-132-ge0ab62a
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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=e0ab62a852e0d3414e85abe9f3e32d966348f677
commit e0ab62a852e0d3414e85abe9f3e32d966348f677
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Fri Mar 25 19:29:41 2016 -0700
Avoid slow backward REP MOVSB
diff --git a/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S b/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S
index 973e6d8..7c33083 100644
--- a/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S
+++ b/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S
@@ -115,6 +115,7 @@ END (MEMMOVE_CHK_ERMS)
# endif
# if VEC_SIZE == 16
+/* Only used to measure performance of REP STOSB. */
# ifdef SHARED
ENTRY (__mempcpy_erms)
movq %rdi, %rax
@@ -125,18 +126,13 @@ END (__mempcpy_erms)
ENTRY (__memmove_erms)
movq %rdi, %rax
-#else
- /* Provide a symbol for debugger. */
-ENTRY (MEMMOVE_ENTRY (MEMMOVE_ERMS))
-# endif
-L(movsb):
movq %rdx, %rcx
cmpq %rsi, %rdi
- jbe L(movsb_forward)
+ jbe 1f
leaq (%rsi,%rcx), %rdx
cmpq %rdx, %rdi
jb L(movsb_backward)
-L(movsb_forward):
+1:
rep movsb
ret
L(movsb_backward):
@@ -146,11 +142,8 @@ L(movsb_backward):
rep movsb
cld
ret
-# if VEC_SIZE == 16
END (__memmove_erms)
strong_alias (__memmove_erms, __memcpy_erms)
-# else
-END (MEMMOVE_ENTRY (MEMMOVE_ERMS))
# endif
ENTRY (MEMMOVE_ERMS)
@@ -179,6 +172,25 @@ L(return):
VZEROUPPER
ret
+L(movsb):
+ movq %rdx, %rcx
+ cmpq %rsi, %rdi
+ jbe 1f
+ leaq (%rsi,%rcx), %rdx
+ cmpq %rdx, %rdi
+ /* Avoid slow backward REP MOVSB. */
+ jb 2f
+1:
+ rep movsb
+ ret
+
+2:
+ movq %rcx, %rdx
+# if REP_MOVSB_THRESHOLD <= (VEC_SIZE * 8)
+# error Unsupported REP_MOVSB_THRESHOLD and VEC_SIZE!
+# endif
+ jmp L(more_8x_vec_backward)
+
.p2align 4,,10
.p2align 4
L(more_2x_vec):
-----------------------------------------------------------------------
Summary of changes:
.../x86_64/multiarch/memmove-vec-unaligned-erms.S | 32 +++++++++++++------
1 files changed, 22 insertions(+), 10 deletions(-)
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