[Bug string/22353] New: sysdeps/i386/i586/strcpy.S isn't maintainable

["hjl.tools at gmail dot com" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=22353

            Bug ID: 22353
           Summary: sysdeps/i386/i586/strcpy.S isn't maintainable
           Product: glibc
           Version: 2.27
            Status: NEW
          Severity: normal
          Priority: P2
         Component: string
          Assignee: unassigned at sourceware dot org
          Reporter: hjl.tools at gmail dot com
  Target Milestone: ---
            Target: i586

sysdeps/i386/i586/strcpy.S has

       andl    $3, %ecx

#ifdef PIC
        call    2f  
        cfi_adjust_cfa_offset (4) 
2:      popl    %edx
        cfi_adjust_cfa_offset (-4)
        /* 0xb is the distance between 2: and 1: but we avoid writing
           1f-2b because the assembler generates worse code.  */
        leal    0xb(%edx,%ecx,8), %ecx
#else
        leal    1f(,%ecx,8), %ecx
#endif

        jmp     *%ecx

        .align 8
1:
        orb     (%esi), %al 
        jz      L(end)
        stosb
        xorl    %eax, %eax
        incl    %esi

        orb     (%esi), %al 
        jz      L(end)
        stosb
        xorl    %eax, %eax
        incl    %esi

        orb     (%esi), %al 
        jz      L(end)
        stosb
        xorl    %eax, %eax
        incl    %esi

L(1):   movl    (%esi), %ecx
        leal    4(%esi),%esi

Change a single instruction will break the jump table.

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