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authorjoseph <joseph@7b3dc134-2b1b-0410-93df-9e9f96275f8d>2013-10-18 21:33:25 +0000
committerjoseph <joseph@7b3dc134-2b1b-0410-93df-9e9f96275f8d>2013-10-18 21:33:25 +0000
commitfe2ed5aaa408e1ab996a9fe1595a05634208a79c (patch)
treee1027fbc9d8a4a8c33f8149b2b42e8cde89c74f6 /libc/sysdeps/x86_64/multiarch/strchr.S
parent571c782b982d888565e7d06bfc2f3d47582fe829 (diff)
Merge changes between r23946 and r24305 from /fsf/trunk.
git-svn-id: svn://svn.eglibc.org/trunk@24306 7b3dc134-2b1b-0410-93df-9e9f96275f8d
Diffstat (limited to 'libc/sysdeps/x86_64/multiarch/strchr.S')
-rw-r--r--libc/sysdeps/x86_64/multiarch/strchr.S127
1 files changed, 0 insertions, 127 deletions
diff --git a/libc/sysdeps/x86_64/multiarch/strchr.S b/libc/sysdeps/x86_64/multiarch/strchr.S
index f170238b5..3f0b2c5f5 100644
--- a/libc/sysdeps/x86_64/multiarch/strchr.S
+++ b/libc/sysdeps/x86_64/multiarch/strchr.S
@@ -29,12 +29,6 @@ ENTRY(strchr)
jne 1f
call __init_cpu_features
1: leaq __strchr_sse2(%rip), %rax
- testl $bit_Slow_SSE4_2, __cpu_features+CPUID_OFFSET+index_Slow_SSE4_2(%rip)
- jnz 2f
- testl $bit_SSE4_2, __cpu_features+CPUID_OFFSET+index_SSE4_2(%rip)
- jz 2f
- leaq __strchr_sse42(%rip), %rax
- ret
2: testl $bit_Slow_BSF, __cpu_features+FEATURE_OFFSET+index_Slow_BSF(%rip)
jz 3f
leaq __strchr_sse2_no_bsf(%rip), %rax
@@ -42,127 +36,6 @@ ENTRY(strchr)
END(strchr)
-/*
- This implementation uses SSE4 instructions to compare up to 16 bytes
- at a time looking for the first occurrence of the character c in the
- string s:
-
- char *strchr (const char *s, int c);
-
- We use 0xa:
- _SIDD_SBYTE_OPS
- | _SIDD_CMP_EQUAL_EACH
- | _SIDD_LEAST_SIGNIFICANT
- on pcmpistri to compare xmm/mem128
-
- 0 1 2 3 4 5 6 7 8 9 A B C D E F
- X X X X X X X X X X X X X X X X
-
- against xmm
-
- 0 1 2 3 4 5 6 7 8 9 A B C D E F
- C C C C C C C C C C C C C C C C
-
- to find out if the first 16byte data element has a byte C and the
- offset of the first byte. There are 3 cases:
-
- 1. The first 16byte data element has the byte C at the offset X.
- 2. The first 16byte data element has EOS and doesn't have the byte C.
- 3. The first 16byte data element is valid and doesn't have the byte C.
-
- Here is the table of ECX, CFlag, ZFlag and SFlag for 3 cases:
-
- case ECX CFlag ZFlag SFlag
- 1 X 1 0/1 0
- 2 16 0 1 0
- 3 16 0 0 0
-
- We exit from the loop for cases 1 and 2 with jbe which branches
- when either CFlag or ZFlag is 1. If CFlag == 1, ECX has the offset
- X for case 1. */
-
- .section .text.sse4.2,"ax",@progbits
- .align 16
- .type __strchr_sse42, @function
- .globl __strchr_sse42
- .hidden __strchr_sse42
-__strchr_sse42:
- cfi_startproc
- CALL_MCOUNT
- testb %sil, %sil
- je __strend_sse4
- pxor %xmm2, %xmm2
- movd %esi, %xmm1
- movl %edi, %ecx
- pshufb %xmm2, %xmm1
- andl $15, %ecx
- movq %rdi, %r8
- je L(aligned_start)
-
-/* Handle unaligned string. */
- andq $-16, %r8
- movdqa (%r8), %xmm0
- pcmpeqb %xmm0, %xmm2
- pcmpeqb %xmm1, %xmm0
- /* Find where NULL is. */
- pmovmskb %xmm2, %edx
- /* Check if there is a match. */
- pmovmskb %xmm0, %esi
- /* Remove the leading bytes. */
- sarl %cl, %edx
- sarl %cl, %esi
- testl %esi, %esi
- je L(unaligned_no_match)
- /* Check which byte is a match. */
- bsfl %esi, %eax
- /* Is there a NULL? */
- testl %edx, %edx
- je L(unaligned_match)
- bsfl %edx, %esi
- cmpl %esi, %eax
- /* Return NULL if NULL comes first. */
- ja L(return_null)
-L(unaligned_match):
- addq %rdi, %rax
- ret
-
- .p2align 4
-L(unaligned_no_match):
- testl %edx, %edx
- jne L(return_null)
-
-/* Loop start on aligned string. */
-L(loop):
- addq $16, %r8
-L(aligned_start):
- pcmpistri $0x2, (%r8), %xmm1
- jbe L(wrap)
- addq $16, %r8
- pcmpistri $0x2, (%r8), %xmm1
- jbe L(wrap)
- addq $16, %r8
- pcmpistri $0x2, (%r8), %xmm1
- jbe L(wrap)
- addq $16, %r8
- pcmpistri $0x2, (%r8), %xmm1
- jbe L(wrap)
- jmp L(loop)
-L(wrap):
- jc L(loop_exit)
-
-/* Return NULL. */
-L(return_null):
- xorl %eax, %eax
- ret
-
-/* Loop exit. */
- .p2align 4
-L(loop_exit):
- leaq (%r8,%rcx), %rax
- ret
- cfi_endproc
- .size __strchr_sse42, .-__strchr_sse42
-
# undef ENTRY
# define ENTRY(name) \