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Re: [PATCH, middle-end]: Fix PR78738, unrecognized insn with -ffast-math


On Thu, Dec 8, 2016 at 10:44 PM, Uros Bizjak <ubizjak@gmail.com> wrote:
> Hello!
>
> Attached patch fixes fall-out from excess-precision improvements
> patch. As shown in the PR, the code throughout the compiler assumes
> FLAG_PRECISION_FAST when flag_unsafe_math_optimizations flag is in
> effect. The patch puts back two lines, removed by excess-precision
> improvements patch.
>
> 2016-12-08  Uros Bizjak  <ubizjak@gmail.com>
>
>     PR middle-end/78738
>     * toplev.c (init_excess_precision): Initialize flag_excess_precision
>     to EXCESS_PRECISION_FAST for flag_unsafe_math_optimizations.
>
> testsuite/ChangeLog:
>
> 2016-12-08  Uros Bizjak  <ubizjak@gmail.com>
>
>     PR middle-end/78738
>     * gcc.target/i386/pr78738.c: New test.
>
> Patch was bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.
>
> OK for mainline?

Hmm, I think it belongs to set_unsafe_math_optimization_flags instead
(and be consistent if -fexcess-precision was manually specified).

Also where do we assume connection between -funsafe-math-optimizations
and FLAG_PRECISION_FAST?  We have two flags so we should fix any
user that looks at one but means the other.

Richard.

>
> Uros.


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