aboutsummaryrefslogtreecommitdiff
path: root/sysdeps
diff options
context:
space:
mode:
authorUlrich Drepper <drepper@redhat.com>2009-06-05 11:32:00 -0700
committerUlrich Drepper <drepper@redhat.com>2009-06-05 11:32:00 -0700
commit3ab2d57a4d00046f1c472abd128517e93e20e485 (patch)
treeaffbd8f72f21440b6d1572bed93d3f84be62e7b3 /sysdeps
parent443caceb354d06724019625ebde083b5151c3fed (diff)
downloadglibc-3ab2d57a4d00046f1c472abd128517e93e20e485.zip
glibc-3ab2d57a4d00046f1c472abd128517e93e20e485.tar.gz
glibc-3ab2d57a4d00046f1c472abd128517e93e20e485.tar.bz2
Optimize x86-64 strlen for SSE4.2.
The SSE4.2 implementation is used in the DSO only. The patch also adds some infrastructure to be used in similar code later one.
Diffstat (limited to 'sysdeps')
-rw-r--r--sysdeps/x86_64/multiarch/Makefile1
-rw-r--r--sysdeps/x86_64/multiarch/ifunc-defines.sym15
-rw-r--r--sysdeps/x86_64/multiarch/init-arch.h2
-rw-r--r--sysdeps/x86_64/multiarch/strlen.S87
4 files changed, 104 insertions, 1 deletions
diff --git a/sysdeps/x86_64/multiarch/Makefile b/sysdeps/x86_64/multiarch/Makefile
index 2a1e910..33d98c3 100644
--- a/sysdeps/x86_64/multiarch/Makefile
+++ b/sysdeps/x86_64/multiarch/Makefile
@@ -1,3 +1,4 @@
ifeq ($(subdir),csu)
aux += init-arch
+gen-as-const-headers += ifunc-defines.sym
endif
diff --git a/sysdeps/x86_64/multiarch/ifunc-defines.sym b/sysdeps/x86_64/multiarch/ifunc-defines.sym
new file mode 100644
index 0000000..48d1287
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/ifunc-defines.sym
@@ -0,0 +1,15 @@
+#include "init-arch.h"
+#include <stddef.h>
+
+--
+
+CPU_FEATURES_SIZE sizeof (struct cpu_features)
+KIND_OFFSET offsetof (struct cpu_features, kind)
+CPUID_OFFSET offsetof (struct cpu_features, cpuid)
+CPUID_SIZE sizeof (struct cpuid_registers)
+CPUID_EAX_OFFSET offsetof (struct cpuid_registers, eax)
+CPUID_EBX_OFFSET offsetof (struct cpuid_registers, ebx)
+CPUID_ECX_OFFSET offsetof (struct cpuid_registers, ecx)
+CPUID_EDX_OFFSET offsetof (struct cpuid_registers, edx)
+
+COMMON_CPUID_INDEX_1
diff --git a/sysdeps/x86_64/multiarch/init-arch.h b/sysdeps/x86_64/multiarch/init-arch.h
index 40b8045..f160ba2 100644
--- a/sysdeps/x86_64/multiarch/init-arch.h
+++ b/sysdeps/x86_64/multiarch/init-arch.h
@@ -35,7 +35,7 @@ extern struct cpu_features
arch_kind_other
} kind;
int max_cpuid;
- struct
+ struct cpuid_registers
{
unsigned int eax;
unsigned int ebx;
diff --git a/sysdeps/x86_64/multiarch/strlen.S b/sysdeps/x86_64/multiarch/strlen.S
new file mode 100644
index 0000000..bf889c1
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/strlen.S
@@ -0,0 +1,87 @@
+/* strlen(str) -- determine the length of the string STR.
+ Copyright (C) 2009 Free Software Foundation, Inc.
+ 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, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <sysdep.h>
+#include <ifunc-defines.h>
+
+
+/* Define multiple versions only for the definition in libc and for
+ the DSO. In static binaries we need strlen before the initialization
+ happened. */
+#if defined SHARED && !defined NOT_IN_libc
+ .text
+ENTRY(strlen)
+ .type strlen, @gnu_indirect_function
+ cmpl $0, __cpu_features+KIND_OFFSET(%rip)
+ jne 1f
+ call __init_cpu_features
+1: leaq __strlen_sse2(%rip), %rax
+ testl $(1<<20), __cpu_features+CPUID_OFFSET+COMMON_CPUID_INDEX_1*CPUID_SIZE+CPUID_ECX_OFFSET(%rip)
+ jz 2f
+ leaq __strlen_sse42(%rip), %rax
+2: ret
+END(strlen)
+
+
+ .type __strlen_sse42, @function
+__strlen_sse42:
+ pxor %xmm2, %xmm2
+ movq %rdi, %rcx
+ movq %rdi, %r8
+ andq $~15, %rdi
+ movdqa %xmm2, %xmm1
+ pcmpeqb (%rdi), %xmm2
+ orl $0xffffffff, %esi
+ subq %rdi, %rcx
+ shll %cl, %esi
+ pmovmskb %xmm2, %edx
+ andl %esi, %edx
+ jnz 1f
+
+2: pcmpistri $0x08, 16(%rdi), %xmm1
+ leaq 16(%rdi), %rdi
+ jnz 2b
+
+ leaq (%rdi,%rcx), %rax
+ subq %r8, %rax
+ ret
+
+1: bsfl %edx, %eax
+ leaq (%rdi,%rax), %rax
+ subq %r8, %rax
+ ret
+ .size __strlen_sse42, .-__strlen_sse42
+
+
+# undef ENTRY
+# define ENTRY(name) \
+ .type __strlen_sse2, @function; __strlen_sse2:
+# undef END
+# define END(name) \
+ .size __strlen_sse2, .-__strlen_sse2
+# undef libc_hidden_builtin_def
+/* It doesn't make sense to send libc-internal strlen calls through a PLT.
+ The speedup we get from using SSE4.2 instruction is likely eaten away
+ by the indirect call in the PLT. */
+# define libc_hidden_builtin_def(name) \
+ .globl __GI_strlen; __GI_strlen = __strlen_sse2
+#endif
+
+#include "../strlen.S"