[Bug regression/40886] [4.3/4.4/4.5 Regression] No loop counter reversal for simple loops anymore

[spop at gcc dot gnu dot org]

------- Comment #10 from spop at gcc dot gnu dot org  2010-02-09 06:00 -------
Note that subtracting 1 from the cost of the candidate IV works as well for
this PR's testcase and we generate this asm with the patch:

        .file   "pr40886.c"
        .text
        .p2align 4,,15
.globl main
        .type   main, @function
main:
.LFB0:
        .cfi_startproc
        pushq   %rbx
        .cfi_def_cfa_offset 16
        movl    $10, %ebx
        .cfi_offset 3, -16
        .p2align 4,,10
        .p2align 3
.L2:
        xorl    %eax, %eax
        call    f2
        subl    $1, %ebx
        jne     .L2
        popq    %rbx
        .cfi_def_cfa_offset 8
        ret
        .cfi_endproc
.LFE0:
        .size   main, .-main
        .ident  "GCC: (GNU) 4.5.0 20100207 (experimental)"
        .section        .note.GNU-stack,"",@progbits


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40886