Fix avx2 strncmp offset compare condition check [BZ #25933]

[thirdparty/glibc.git] / sysdeps / x86_64 / multiarch / strcmp-avx2.S

diff --git a/sysdeps/x86_64/multiarch/strcmp-avx2.S b/sysdeps/x86_64/multiarch/strcmp-avx2.S
index 78fc116877f1437f51afce96ac4ee8cc3c7e3a13..156c19496a31335361e198c21524fcaec016d3c9 100644 (file)
--- a/sysdeps/x86_64/multiarch/strcmp-avx2.S
+++ b/sysdeps/x86_64/multiarch/strcmp-avx2.S
@@ -591,7 +591,14 @@ L(loop_cross_page_2_vec):
        movl    $(PAGE_SIZE / (VEC_SIZE * 4) - 1), %esi
 
        testq   %rdi, %rdi
+# ifdef USE_AS_STRNCMP
+       /* At this point, if %rdi value is 0, it already tested
+          VEC_SIZE*4+%r10 byte starting from %rax. This label
+          checks whether strncmp maximum offset reached or not.  */
+       je      L(string_nbyte_offset_check)
+# else
        je      L(back_to_loop)
+# endif
        tzcntq  %rdi, %rcx
        addq    %r10, %rcx
        /* Adjust for number of bytes skipped.  */
@@ -627,6 +634,14 @@ L(loop_cross_page_2_vec):
        VZEROUPPER
        ret
 
+# ifdef USE_AS_STRNCMP
+L(string_nbyte_offset_check):
+       leaq    (VEC_SIZE * 4)(%r10), %r10
+       cmpq    %r10, %r11
+       jbe     L(zero)
+       jmp     L(back_to_loop)
+# endif
+
        .p2align 4
 L(cross_page_loop):
        /* Check one byte/dword at a time.  */