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Use-new-strlen-implementation-in-rtld
- From: OndÅej BÃlka <neleai at seznam dot cz>
- To: libc-alpha at sourceware dot org
- Date: Thu, 31 Jan 2013 13:37:14 +0100
- Subject: Use-new-strlen-implementation-in-rtld
To also use my implementation of strlen in runtime linker
use following patch.
It uses fact that xmm are call clobbered and only xmm0-xmm7 can be
used to pass arguments so xmm8-xmm15 are available.
2013-01-31 OndÅej BÃlka <neleai@seznam.cz>
* sysdeps/x86/tst-xmmymm.sh: Check only xmm0-xmm7
* sysdeps/x86_64/rtld-strlen.S: Use sse2 implementation
---
sysdeps/x86/tst-xmmymm.sh | 2 +-
sysdeps/x86_64/rtld-strlen.S | 139 +-----------------------------------------
2 files changed, 2 insertions(+), 139 deletions(-)
diff --git a/sysdeps/x86/tst-xmmymm.sh b/sysdeps/x86/tst-xmmymm.sh
index 0883e40..0d112b7 100755
--- a/sysdeps/x86/tst-xmmymm.sh
+++ b/sysdeps/x86/tst-xmmymm.sh
@@ -80,7 +80,7 @@ echo "object files needed: $tocheck"
cp /dev/null "$tmp"
for f in $tocheck; do
$OBJDUMP -d "$objpfx"../*/"$f" |
- awk 'BEGIN { last="" } /^[[:xdigit:]]* <[_[:alnum:]]*>:$/ { fct=substr($2, 2, length($2)-3) } /,%[xy]mm[[:digit:]]*$/ { if (last != fct) { print fct; last=fct} }' |
+ awk 'BEGIN { last="" } /^[[:xdigit:]]* <[_[:alnum:]]*>:$/ { fct=substr($2, 2, length($2)-3) } /,%[xy]mm[01234567][^012345]$/ { if (last != fct) { print fct; last=fct} }' |
while read fct; do
if test "$fct" = "_dl_runtime_profile" -o "$fct" = "_dl_x86_64_restore_sse"; then
continue;
diff --git a/sysdeps/x86_64/rtld-strlen.S b/sysdeps/x86_64/rtld-strlen.S
index bb23b55..71be00b 100644
--- a/sysdeps/x86_64/rtld-strlen.S
+++ b/sysdeps/x86_64/rtld-strlen.S
@@ -1,138 +1 @@
-/* strlen(str) -- determine the length of the string STR.
- Copyright (C) 2002-2013 Free Software Foundation, Inc.
- Based on i486 version contributed by Ulrich Drepper <drepper@redhat.com>.
- This file is part of the GNU C Library.
-
- The GNU C Library is free software; you can redistribute it and/or
- modify it under the terms of the GNU Lesser General Public
- License as published by the Free Software Foundation; either
- version 2.1 of the License, or (at your option) any later version.
-
- The GNU C Library is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public
- License along with the GNU C Library; if not, see
- <http://www.gnu.org/licenses/>. */
-
-#include <sysdep.h>
-#include "asm-syntax.h"
-#include "bp-sym.h"
-#include "bp-asm.h"
-
-
- .text
-ENTRY (strlen)
- movq %rdi, %rcx /* Duplicate source pointer. */
- andl $7, %ecx /* mask alignment bits */
- movq %rdi, %rax /* duplicate destination. */
- jz 1f /* aligned => start loop */
-
- neg %ecx /* We need to align to 8 bytes. */
- addl $8,%ecx
- /* Search the first bytes directly. */
-0: cmpb $0x0,(%rax) /* is byte NUL? */
- je 2f /* yes => return */
- incq %rax /* increment pointer */
- decl %ecx
- jnz 0b
-
-1: movq $0xfefefefefefefeff,%r8 /* Save magic. */
-
- .p2align 4 /* Align loop. */
-4: /* Main Loop is unrolled 4 times. */
- /* First unroll. */
- movq (%rax), %rcx /* get double word (= 8 bytes) in question */
- addq $8,%rax /* adjust pointer for next word */
- movq %r8, %rdx /* magic value */
- addq %rcx, %rdx /* add the magic value to the word. We get
- carry bits reported for each byte which
- is *not* 0 */
- jnc 3f /* highest byte is NUL => return pointer */
- xorq %rcx, %rdx /* (word+magic)^word */
- orq %r8, %rdx /* set all non-carry bits */
- incq %rdx /* add 1: if one carry bit was *not* set
- the addition will not result in 0. */
- jnz 3f /* found NUL => return pointer */
-
- /* Second unroll. */
- movq (%rax), %rcx /* get double word (= 8 bytes) in question */
- addq $8,%rax /* adjust pointer for next word */
- movq %r8, %rdx /* magic value */
- addq %rcx, %rdx /* add the magic value to the word. We get
- carry bits reported for each byte which
- is *not* 0 */
- jnc 3f /* highest byte is NUL => return pointer */
- xorq %rcx, %rdx /* (word+magic)^word */
- orq %r8, %rdx /* set all non-carry bits */
- incq %rdx /* add 1: if one carry bit was *not* set
- the addition will not result in 0. */
- jnz 3f /* found NUL => return pointer */
-
- /* Third unroll. */
- movq (%rax), %rcx /* get double word (= 8 bytes) in question */
- addq $8,%rax /* adjust pointer for next word */
- movq %r8, %rdx /* magic value */
- addq %rcx, %rdx /* add the magic value to the word. We get
- carry bits reported for each byte which
- is *not* 0 */
- jnc 3f /* highest byte is NUL => return pointer */
- xorq %rcx, %rdx /* (word+magic)^word */
- orq %r8, %rdx /* set all non-carry bits */
- incq %rdx /* add 1: if one carry bit was *not* set
- the addition will not result in 0. */
- jnz 3f /* found NUL => return pointer */
-
- /* Fourth unroll. */
- movq (%rax), %rcx /* get double word (= 8 bytes) in question */
- addq $8,%rax /* adjust pointer for next word */
- movq %r8, %rdx /* magic value */
- addq %rcx, %rdx /* add the magic value to the word. We get
- carry bits reported for each byte which
- is *not* 0 */
- jnc 3f /* highest byte is NUL => return pointer */
- xorq %rcx, %rdx /* (word+magic)^word */
- orq %r8, %rdx /* set all non-carry bits */
- incq %rdx /* add 1: if one carry bit was *not* set
- the addition will not result in 0. */
- jz 4b /* no NUL found => continue loop */
-
- .p2align 4 /* Align, it's a jump target. */
-3: subq $8,%rax /* correct pointer increment. */
-
- testb %cl, %cl /* is first byte NUL? */
- jz 2f /* yes => return */
- incq %rax /* increment pointer */
-
- testb %ch, %ch /* is second byte NUL? */
- jz 2f /* yes => return */
- incq %rax /* increment pointer */
-
- testl $0x00ff0000, %ecx /* is third byte NUL? */
- jz 2f /* yes => return pointer */
- incq %rax /* increment pointer */
-
- testl $0xff000000, %ecx /* is fourth byte NUL? */
- jz 2f /* yes => return pointer */
- incq %rax /* increment pointer */
-
- shrq $32, %rcx /* look at other half. */
-
- testb %cl, %cl /* is first byte NUL? */
- jz 2f /* yes => return */
- incq %rax /* increment pointer */
-
- testb %ch, %ch /* is second byte NUL? */
- jz 2f /* yes => return */
- incq %rax /* increment pointer */
-
- testl $0xff0000, %ecx /* is third byte NUL? */
- jz 2f /* yes => return pointer */
- incq %rax /* increment pointer */
-2:
- subq %rdi, %rax /* compute difference to string start */
- ret
-END (strlen)
-libc_hidden_builtin_def (strlen)
+#include "sysdeps/x86_64/strlen.S"
--
1.7.4.4