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x86: Fix overflow bug in wcsnlen-sse4_1 and wcsnlen-avx2 [BZ #27974]
This commit fixes the bug mentioned in the previous commit. The previous implementations of wmemchr in these files relied on maxlen * sizeof(wchar_t) which was not guranteed by the standard. The new overflow tests added in the previous commit now pass (As well as all the other tests). Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com> Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
This commit is contained in:
Noah Goldstein
parent
645a158978
commit
a775a7a3eb
@ -44,21 +44,21 @@
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# define VEC_SIZE 32
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# define PAGE_SIZE 4096
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# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE)
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.section SECTION(.text),"ax",@progbits
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ENTRY (STRLEN)
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# ifdef USE_AS_STRNLEN
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/* Check zero length. */
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# ifdef __ILP32__
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/* Clear upper bits. */
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and %RSI_LP, %RSI_LP
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# else
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test %RSI_LP, %RSI_LP
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# endif
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jz L(zero)
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/* Store max len in R8_LP before adjusting if using WCSLEN. */
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mov %RSI_LP, %R8_LP
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# ifdef USE_AS_WCSLEN
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shl $2, %RSI_LP
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# elif defined __ILP32__
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/* Clear the upper 32 bits. */
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movl %esi, %esi
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# endif
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# endif
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movl %edi, %eax
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movq %rdi, %rdx
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@ -72,10 +72,10 @@ ENTRY (STRLEN)
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/* Check the first VEC_SIZE bytes. */
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VPCMPEQ (%rdi), %ymm0, %ymm1
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vpmovmskb %ymm1, %eax
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vpmovmskb %ymm1, %eax
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# ifdef USE_AS_STRNLEN
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/* If length < VEC_SIZE handle special. */
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cmpq $VEC_SIZE, %rsi
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cmpq $CHAR_PER_VEC, %rsi
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jbe L(first_vec_x0)
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# endif
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/* If empty continue to aligned_more. Otherwise return bit
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@ -84,6 +84,7 @@ ENTRY (STRLEN)
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jz L(aligned_more)
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tzcntl %eax, %eax
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get wchar_t count. */
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shrl $2, %eax
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# endif
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VZEROUPPER_RETURN
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@ -97,9 +98,14 @@ L(zero):
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L(first_vec_x0):
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/* Set bit for max len so that tzcnt will return min of max len
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and position of first match. */
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# ifdef USE_AS_WCSLEN
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/* NB: Multiply length by 4 to get byte count. */
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sall $2, %esi
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# endif
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btsq %rsi, %rax
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tzcntl %eax, %eax
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get wchar_t count. */
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shrl $2, %eax
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# endif
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VZEROUPPER_RETURN
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@ -113,14 +119,19 @@ L(first_vec_x1):
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# ifdef USE_AS_STRNLEN
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/* Use ecx which was computed earlier to compute correct value.
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*/
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# ifdef USE_AS_WCSLEN
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leal -(VEC_SIZE * 4 + 1)(%rax, %rcx, 4), %eax
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# else
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subl $(VEC_SIZE * 4 + 1), %ecx
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addl %ecx, %eax
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# endif
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# else
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subl %edx, %edi
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incl %edi
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addl %edi, %eax
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# endif
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get wchar_t count. */
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shrl $2, %eax
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# endif
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VZEROUPPER_RETURN
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@ -133,14 +144,19 @@ L(first_vec_x2):
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# ifdef USE_AS_STRNLEN
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/* Use ecx which was computed earlier to compute correct value.
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*/
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# ifdef USE_AS_WCSLEN
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leal -(VEC_SIZE * 3 + 1)(%rax, %rcx, 4), %eax
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# else
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subl $(VEC_SIZE * 3 + 1), %ecx
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addl %ecx, %eax
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# endif
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# else
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subl %edx, %edi
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addl $(VEC_SIZE + 1), %edi
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addl %edi, %eax
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# endif
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get wchar_t count. */
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shrl $2, %eax
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# endif
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VZEROUPPER_RETURN
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@ -153,14 +169,19 @@ L(first_vec_x3):
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# ifdef USE_AS_STRNLEN
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/* Use ecx which was computed earlier to compute correct value.
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*/
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# ifdef USE_AS_WCSLEN
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leal -(VEC_SIZE * 2 + 1)(%rax, %rcx, 4), %eax
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# else
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subl $(VEC_SIZE * 2 + 1), %ecx
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addl %ecx, %eax
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# endif
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# else
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subl %edx, %edi
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addl $(VEC_SIZE * 2 + 1), %edi
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addl %edi, %eax
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# endif
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get wchar_t count. */
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shrl $2, %eax
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# endif
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VZEROUPPER_RETURN
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@ -173,14 +194,19 @@ L(first_vec_x4):
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# ifdef USE_AS_STRNLEN
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/* Use ecx which was computed earlier to compute correct value.
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*/
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# ifdef USE_AS_WCSLEN
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leal -(VEC_SIZE * 1 + 1)(%rax, %rcx, 4), %eax
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# else
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subl $(VEC_SIZE + 1), %ecx
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addl %ecx, %eax
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# endif
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# else
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subl %edx, %edi
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addl $(VEC_SIZE * 3 + 1), %edi
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addl %edi, %eax
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# endif
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get wchar_t count. */
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shrl $2, %eax
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# endif
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VZEROUPPER_RETURN
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@ -195,10 +221,14 @@ L(cross_page_continue):
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/* Check the first 4 * VEC_SIZE. Only one VEC_SIZE at a time
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since data is only aligned to VEC_SIZE. */
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# ifdef USE_AS_STRNLEN
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/* + 1 because rdi is aligned to VEC_SIZE - 1. + CHAR_SIZE because
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it simplies the logic in last_4x_vec_or_less. */
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/* + 1 because rdi is aligned to VEC_SIZE - 1. + CHAR_SIZE
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because it simplies the logic in last_4x_vec_or_less. */
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leaq (VEC_SIZE * 4 + CHAR_SIZE + 1)(%rdi), %rcx
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subq %rdx, %rcx
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get the wchar_t count. */
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sarl $2, %ecx
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# endif
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# endif
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/* Load first VEC regardless. */
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VPCMPEQ 1(%rdi), %ymm0, %ymm1
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@ -207,34 +237,38 @@ L(cross_page_continue):
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subq %rcx, %rsi
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jb L(last_4x_vec_or_less)
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# endif
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vpmovmskb %ymm1, %eax
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vpmovmskb %ymm1, %eax
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testl %eax, %eax
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jnz L(first_vec_x1)
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VPCMPEQ (VEC_SIZE + 1)(%rdi), %ymm0, %ymm1
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vpmovmskb %ymm1, %eax
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vpmovmskb %ymm1, %eax
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testl %eax, %eax
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jnz L(first_vec_x2)
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VPCMPEQ (VEC_SIZE * 2 + 1)(%rdi), %ymm0, %ymm1
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vpmovmskb %ymm1, %eax
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vpmovmskb %ymm1, %eax
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testl %eax, %eax
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jnz L(first_vec_x3)
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VPCMPEQ (VEC_SIZE * 3 + 1)(%rdi), %ymm0, %ymm1
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vpmovmskb %ymm1, %eax
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vpmovmskb %ymm1, %eax
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testl %eax, %eax
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jnz L(first_vec_x4)
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/* Align data to VEC_SIZE * 4 - 1. */
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# ifdef USE_AS_STRNLEN
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/* Before adjusting length check if at last VEC_SIZE * 4. */
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cmpq $(VEC_SIZE * 4 - 1), %rsi
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cmpq $(CHAR_PER_VEC * 4 - 1), %rsi
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jbe L(last_4x_vec_or_less_load)
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incq %rdi
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movl %edi, %ecx
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orq $(VEC_SIZE * 4 - 1), %rdi
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andl $(VEC_SIZE * 4 - 1), %ecx
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get the wchar_t count. */
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sarl $2, %ecx
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# endif
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/* Readjust length. */
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addq %rcx, %rsi
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# else
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@ -246,13 +280,13 @@ L(cross_page_continue):
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L(loop_4x_vec):
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# ifdef USE_AS_STRNLEN
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/* Break if at end of length. */
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subq $(VEC_SIZE * 4), %rsi
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subq $(CHAR_PER_VEC * 4), %rsi
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jb L(last_4x_vec_or_less_cmpeq)
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# endif
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/* Save some code size by microfusing VPMINU with the load. Since
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the matches in ymm2/ymm4 can only be returned if there where no
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matches in ymm1/ymm3 respectively there is no issue with overlap.
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*/
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/* Save some code size by microfusing VPMINU with the load.
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Since the matches in ymm2/ymm4 can only be returned if there
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where no matches in ymm1/ymm3 respectively there is no issue
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with overlap. */
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vmovdqa 1(%rdi), %ymm1
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VPMINU (VEC_SIZE + 1)(%rdi), %ymm1, %ymm2
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vmovdqa (VEC_SIZE * 2 + 1)(%rdi), %ymm3
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@ -260,7 +294,7 @@ L(loop_4x_vec):
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VPMINU %ymm2, %ymm4, %ymm5
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VPCMPEQ %ymm5, %ymm0, %ymm5
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vpmovmskb %ymm5, %ecx
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vpmovmskb %ymm5, %ecx
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subq $-(VEC_SIZE * 4), %rdi
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testl %ecx, %ecx
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@ -268,27 +302,28 @@ L(loop_4x_vec):
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VPCMPEQ %ymm1, %ymm0, %ymm1
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vpmovmskb %ymm1, %eax
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vpmovmskb %ymm1, %eax
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subq %rdx, %rdi
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testl %eax, %eax
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jnz L(last_vec_return_x0)
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VPCMPEQ %ymm2, %ymm0, %ymm2
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vpmovmskb %ymm2, %eax
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vpmovmskb %ymm2, %eax
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testl %eax, %eax
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jnz L(last_vec_return_x1)
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/* Combine last 2 VEC. */
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VPCMPEQ %ymm3, %ymm0, %ymm3
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vpmovmskb %ymm3, %eax
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/* rcx has combined result from all 4 VEC. It will only be used if
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the first 3 other VEC all did not contain a match. */
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vpmovmskb %ymm3, %eax
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/* rcx has combined result from all 4 VEC. It will only be used
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if the first 3 other VEC all did not contain a match. */
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salq $32, %rcx
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orq %rcx, %rax
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tzcntq %rax, %rax
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subq $(VEC_SIZE * 2 - 1), %rdi
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addq %rdi, %rax
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get wchar_t count. */
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shrq $2, %rax
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# endif
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VZEROUPPER_RETURN
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@ -297,15 +332,19 @@ L(loop_4x_vec):
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# ifdef USE_AS_STRNLEN
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.p2align 4
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L(last_4x_vec_or_less_load):
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/* Depending on entry adjust rdi / prepare first VEC in ymm1. */
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/* Depending on entry adjust rdi / prepare first VEC in ymm1.
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*/
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subq $-(VEC_SIZE * 4), %rdi
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L(last_4x_vec_or_less_cmpeq):
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VPCMPEQ 1(%rdi), %ymm0, %ymm1
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L(last_4x_vec_or_less):
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vpmovmskb %ymm1, %eax
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/* If remaining length > VEC_SIZE * 2. This works if esi is off by
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VEC_SIZE * 4. */
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# ifdef USE_AS_WCSLEN
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/* NB: Multiply length by 4 to get byte count. */
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sall $2, %esi
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# endif
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vpmovmskb %ymm1, %eax
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/* If remaining length > VEC_SIZE * 2. This works if esi is off
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by VEC_SIZE * 4. */
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testl $(VEC_SIZE * 2), %esi
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jnz L(last_4x_vec)
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@ -320,7 +359,7 @@ L(last_4x_vec_or_less):
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jb L(max)
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VPCMPEQ (VEC_SIZE + 1)(%rdi), %ymm0, %ymm1
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vpmovmskb %ymm1, %eax
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vpmovmskb %ymm1, %eax
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tzcntl %eax, %eax
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/* Check the end of data. */
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cmpl %eax, %esi
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@ -329,6 +368,7 @@ L(last_4x_vec_or_less):
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addl $(VEC_SIZE + 1), %eax
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addq %rdi, %rax
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get wchar_t count. */
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shrq $2, %rax
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# endif
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VZEROUPPER_RETURN
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@ -340,6 +380,7 @@ L(last_vec_return_x0):
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subq $(VEC_SIZE * 4 - 1), %rdi
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addq %rdi, %rax
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get wchar_t count. */
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shrq $2, %rax
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# endif
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VZEROUPPER_RETURN
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@ -350,6 +391,7 @@ L(last_vec_return_x1):
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subq $(VEC_SIZE * 3 - 1), %rdi
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addq %rdi, %rax
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get wchar_t count. */
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shrq $2, %rax
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# endif
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VZEROUPPER_RETURN
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@ -366,6 +408,7 @@ L(last_vec_x1_check):
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incl %eax
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addq %rdi, %rax
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get wchar_t count. */
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shrq $2, %rax
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# endif
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VZEROUPPER_RETURN
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@ -381,14 +424,14 @@ L(last_4x_vec):
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jnz L(last_vec_x1)
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VPCMPEQ (VEC_SIZE + 1)(%rdi), %ymm0, %ymm1
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vpmovmskb %ymm1, %eax
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vpmovmskb %ymm1, %eax
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testl %eax, %eax
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jnz L(last_vec_x2)
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/* Normalize length. */
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andl $(VEC_SIZE * 4 - 1), %esi
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VPCMPEQ (VEC_SIZE * 2 + 1)(%rdi), %ymm0, %ymm1
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vpmovmskb %ymm1, %eax
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vpmovmskb %ymm1, %eax
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testl %eax, %eax
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jnz L(last_vec_x3)
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@ -396,7 +439,7 @@ L(last_4x_vec):
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jb L(max)
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VPCMPEQ (VEC_SIZE * 3 + 1)(%rdi), %ymm0, %ymm1
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vpmovmskb %ymm1, %eax
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vpmovmskb %ymm1, %eax
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tzcntl %eax, %eax
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/* Check the end of data. */
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cmpl %eax, %esi
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@ -405,6 +448,7 @@ L(last_4x_vec):
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addl $(VEC_SIZE * 3 + 1), %eax
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addq %rdi, %rax
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get wchar_t count. */
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shrq $2, %rax
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# endif
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VZEROUPPER_RETURN
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@ -419,6 +463,7 @@ L(last_vec_x1):
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incl %eax
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addq %rdi, %rax
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get wchar_t count. */
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shrq $2, %rax
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# endif
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VZEROUPPER_RETURN
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@ -432,6 +477,7 @@ L(last_vec_x2):
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addl $(VEC_SIZE + 1), %eax
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addq %rdi, %rax
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get wchar_t count. */
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shrq $2, %rax
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# endif
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VZEROUPPER_RETURN
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@ -447,6 +493,7 @@ L(last_vec_x3):
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addl $(VEC_SIZE * 2 + 1), %eax
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addq %rdi, %rax
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get wchar_t count. */
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shrq $2, %rax
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# endif
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VZEROUPPER_RETURN
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@ -455,13 +502,13 @@ L(max_end):
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VZEROUPPER_RETURN
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# endif
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/* Cold case for crossing page with first load. */
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/* Cold case for crossing page with first load. */
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.p2align 4
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L(cross_page_boundary):
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/* Align data to VEC_SIZE - 1. */
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orq $(VEC_SIZE - 1), %rdi
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VPCMPEQ -(VEC_SIZE - 1)(%rdi), %ymm0, %ymm1
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vpmovmskb %ymm1, %eax
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vpmovmskb %ymm1, %eax
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/* Remove the leading bytes. sarxl only uses bits [5:0] of COUNT
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so no need to manually mod rdx. */
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sarxl %edx, %eax, %eax
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@ -470,6 +517,10 @@ L(cross_page_boundary):
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jnz L(cross_page_less_vec)
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leaq 1(%rdi), %rcx
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subq %rdx, %rcx
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# ifdef USE_AS_WCSLEN
|
||||
/* NB: Divide bytes by 4 to get wchar_t count. */
|
||||
shrl $2, %ecx
|
||||
# endif
|
||||
/* Check length. */
|
||||
cmpq %rsi, %rcx
|
||||
jb L(cross_page_continue)
|
||||
@ -479,6 +530,7 @@ L(cross_page_boundary):
|
||||
jz L(cross_page_continue)
|
||||
tzcntl %eax, %eax
|
||||
# ifdef USE_AS_WCSLEN
|
||||
/* NB: Divide length by 4 to get wchar_t count. */
|
||||
shrl $2, %eax
|
||||
# endif
|
||||
# endif
|
||||
@ -489,6 +541,10 @@ L(return_vzeroupper):
|
||||
.p2align 4
|
||||
L(cross_page_less_vec):
|
||||
tzcntl %eax, %eax
|
||||
# ifdef USE_AS_WCSLEN
|
||||
/* NB: Multiply length by 4 to get byte count. */
|
||||
sall $2, %esi
|
||||
# endif
|
||||
cmpq %rax, %rsi
|
||||
cmovb %esi, %eax
|
||||
# ifdef USE_AS_WCSLEN
|
||||
|
||||
@ -65,12 +65,25 @@ ENTRY(strlen)
|
||||
ret
|
||||
L(n_nonzero):
|
||||
# ifdef AS_WCSLEN
|
||||
shl $2, %RSI_LP
|
||||
/* Check for overflow from maxlen * sizeof(wchar_t). If it would
|
||||
overflow the only way this program doesn't have undefined behavior
|
||||
is if there is a null terminator in valid memory so wcslen will
|
||||
suffice. */
|
||||
mov %RSI_LP, %R10_LP
|
||||
sar $62, %R10_LP
|
||||
test %R10_LP, %R10_LP
|
||||
jnz __wcslen_sse4_1
|
||||
sal $2, %RSI_LP
|
||||
# endif
|
||||
|
||||
|
||||
/* Initialize long lived registers. */
|
||||
|
||||
add %RDI_LP, %RSI_LP
|
||||
# ifdef AS_WCSLEN
|
||||
/* Check for overflow again from s + maxlen * sizeof(wchar_t). */
|
||||
jbe __wcslen_sse4_1
|
||||
# endif
|
||||
mov %RSI_LP, %R10_LP
|
||||
and $-64, %R10_LP
|
||||
mov %RSI_LP, %R11_LP
|
||||
|
||||
Loading…
Reference in New Issue
Block a user