[Bug c/36232] Optimizer removes condition check to terminate loop

[nick dot spence at freescale dot com]

------- Comment #3 from nick dot spence at freescale dot com  2008-05-13 19:56 
-------
The code has two loops, which compile correctly when no optimization, or
-O1 are used, but the second loop becomes infinite if -Os or -O2 is used.

        .file   "test.c"
        .section        .rodata.str1.1,"aMS",@progbits,1
.LC0:
        .string "\n reads %d, 0x%08X"
        .text
.globl main
        .type   main, @function
main:
        leal    4(%esp), %ecx
        andl    $-16, %esp
        pushl   -4(%ecx)
        pushl   %ebp
        movl    %esp, %ebp
        pushl   %esi
        pushl   %ebx
        xorl    %ebx, %ebx
        pushl   %ecx
        subl    $12, %esp
.L2:
        movl    $0, (%ebx)
        addl    $4, %ebx
        cmpl    $64, %ebx
        jne     .L2         /* branch condition for first loop */
        xorl    %esi, %esi
.L4:
        pushl   %eax
        pushl   %ebx
        subl    $4, %ebx
        pushl   %esi
        incl    %esi
        pushl   $.LC0
        call    printf
        movl    (%ebx), %eax
        addl    $16, %esp
        jmp     .L4            /* branch condition for second loop was lost */
        .size   main, .-main
        .ident  "GCC: (GNU) 4.1.2 20070626 (Red Hat 4.1.2-13)"
        .section        .note.GNU-stack,"",@progbits


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36232