[Bug tree-optimization/43529] G++ doesn't optimize away empty loop when index is a double

[changpeng dot fang at amd dot com]

------- Comment #3 from changpeng dot fang at amd dot com  2010-06-04 23:29 
-------
(In reply to comment #2)
> Interesting! What's the difference between 17 and 18?
> ------------
> int main()
> {
>   double i;
>   for(i=0; i<18; i+=1); /* gcc -O3, empty loop not removed */
> }


The funny thing occurs in gcc 4, not gcc 6:

        .file   "empty.c"
        .text
        .p2align 4,,15
.globl main
        .type   main, @function
main:
.LFB0:
        .cfi_startproc
        xorl    %eax, %eax
        .p2align 4,,10
        .p2align 3
.L2:
        addl    $1, %eax
        cmpl    $18, %eax
        jne     .L2
        rep
        ret
        .cfi_endproc
.LFE0:
        .size   main, .-main
        .ident  "GCC: (Ubuntu 4.4.1-4ubuntu9) 4.4.1"
        .section        .note.GNU-stack,"",@progbits


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43529