[Bug tree-optimization/56309] -O3 optimizer generates conditional moves instead of compare and branch resulting in almost 2x slower code

[arturomdn at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56309

--- Comment #16 from arturomdn at gmail dot com 2013-02-14 17:42:55 UTC ---
With -ftree-vectorize -fno-tree-loop-if-convert flags it generated this for the
loop in question:

.L39:
        movq    %rdi, %rdx
        addq    (%rsi,%rax,8), %rcx
        imulq   (%r9,%rax,8), %rdx
        addq    %rcx, %rdx
        xorl    %ecx, %ecx
        cmpq    %r10, %rdx
        jbe     .L38
        movq    %rdx, %rcx
        andl    $4294967295, %edx
        shrq    $32, %rcx
.L38:
        addq    $1, %rax
        cmpq    %r8, %rax
        movq    %rdx, -8(%rsi,%rax,8)
        jne     .L39

And it executed fast:

./by-val-O3-flags
Took 6.74 seconds total.