[Bug target/63599] "wrong" branch optimization with Ofast in a loop

["pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63599

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The tree level looks like this:
  t_13 = VEC_COND_EXPR <t_4 <= { 4.142135679721832275390625e-1,
4.142135679721832275390625e-1, 4.142135679721832275390625e-1,
4.142135679721832275390625e-1 }, t_4, _12>;
  ret_14 = VEC_COND_EXPR <t_4 > { 4.142135679721832275390625e-1,
4.142135679721832275390625e-1, 4.142135679721832275390625e-1,
4.142135679721832275390625e-1 }, { 7.85398185253143310546875e-1,
7.85398185253143310546875e-1, 7.85398185253143310546875e-1,
7.85398185253143310546875e-1 }, { 0.0, 0.0, 0.0, 0.0 }>;
  t_16 = _9 != 0 ? t_13 : t_4;
  ret_15 = _9 != 0 ? ret_14 : { 0.0, 0.0, 0.0, 0.0 };


>"movmskps	%xmm8, %edx"
> does not protect the code in the if block...
Yes it does just not the way you think it does.

Notice the last two statements are conditional expressions.

And that gets translated into the following:
    testl    %edx, %edx
    jne    .L9
    movaps    %xmm3, %xmm1
    pxor    %xmm2, %xmm2
.L9:

So if anything it is a missed optimization dealing with conditional moves with
vectors without a vector comparison.
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From: "rguenther at suse dot de" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/54488] tree loop invariant motion uses an excessive amount of memory
Date: Mon, 20 Oct 2014 07:44:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idT488

--- Comment #6 from rguenther at suse dot de <rguenther at suse dot de> ---
On Sun, 19 Oct 2014, evgeniya.maenkova at gmail dot com wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?idT488
>
> --- Comment #5 from Evgeniya Maenkova <evgeniya.maenkova at gmail dot com> ---
> Also, I collect massif data and see no tree-ssa-lim in it (i mean in top
> contributors).
>
> So what do you think?
>
> (How did you measured 1,8Gb caused by lim? - this is for me to understand
> whether this bug is actual or not)

I basically watched 'top' with breakpoints at the start and end of LIM.