[Bug tree-optimization/91645] Missed optimization with sqrt(x*x)

[rguenther at suse dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91645

--- Comment #4 from rguenther at suse dot de <rguenther at suse dot de> ---
On Wed, 4 Sep 2019, lisyarus at gmail dot com wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91645
> 
> --- Comment #2 from Nikita Lisitsa <lisyarus at gmail dot com> ---
> If by 'isless(y, 0.0)' you mean 'y < 0.f', then no, it doesn't change anything,
> it produces the same 'ucomiss ... call sqrtf' boilerplate. May I have
> misunderstood you?

I meant isless literally, it's from math.h

> By the way, what about '#pragma GCC optimize ("no-math-errno")'? Is it supposed
> to work? Should I issue another bug on that matter?

It should work if the #pragma is before the function start (those pragmas 
only work on function granularity)