Re: [PATCH] FMA_EXPR can cause -fnon-call-exceptions with floating point args (PR middle-end/79396)

[Richard Biener <rguenther@suse.de>]

On Sat, 25 Feb 2017, Jakub Jelinek wrote:

> On Sat, Feb 25, 2017 at 08:42:33AM +0100, Richard Biener wrote:
> > On February 24, 2017 9:56:25 PM GMT+01:00, Jakub Jelinek <jakub@redhat.com> wrote:
> > >Hi!
> > >
> > >On the following testcase we replace a PLUS_EXPR (which is considered
> > >throwing with -fnon-call-exceptions when it has floating point
> > >arguments
> > >and FP exceptions or sNaNs are enabled) with a FMA_EXPR; I believe it
> > >can throw the same, but stmt_could_throw_1_p doesn't think so (as it is
> > >not unary/binary/comparison).  While we could tweak the widen_mul patch
> > >to deal with dropping EH from gsi_replace and cleaning up cfg etc., I
> > >believe the right fix is to fix stmt_could_throw_1_p.
> > >
> > >Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> > 
> > OK.  Can you make sure this is then consistent with the other throw predicates?.
> 
> may_trap_p_1 handles FMA right, no idea what other predicates could cover
> that on RTL.  But you're right, operation_could_trap_p used by
> tree_could_trap_p needs the same treatment:

Yes, that was what I remembered (used for example by vn_nary_may_trap).

Ok.

Thanks,
Richard.

> 2017-02-25  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR middle-end/79396
> 	* tree-eh.c (operation_could_trap_p, stmt_could_throw_1_p): Handle
> 	FMA_EXPR like tcc_binary or tcc_unary.
> 
> 	* g++.dg/opt/pr79396.C: New test.
> 
> --- gcc/tree-eh.c.jj	2017-02-24 21:39:01.240088691 +0100
> +++ gcc/tree-eh.c	2017-02-25 09:21:06.017859379 +0100
> @@ -2513,7 +2513,8 @@ operation_could_trap_p (enum tree_code o
>  
>    if (TREE_CODE_CLASS (op) != tcc_comparison
>        && TREE_CODE_CLASS (op) != tcc_unary
> -      && TREE_CODE_CLASS (op) != tcc_binary)
> +      && TREE_CODE_CLASS (op) != tcc_binary
> +      && op != FMA_EXPR)
>      return false;
>  
>    return operation_could_trap_helper_p (op, fp_operation, honor_trapv,
> @@ -2738,7 +2739,8 @@ stmt_could_throw_1_p (gimple *stmt)
>  
>    if (TREE_CODE_CLASS (code) == tcc_comparison
>        || TREE_CODE_CLASS (code) == tcc_unary
> -      || TREE_CODE_CLASS (code) == tcc_binary)
> +      || TREE_CODE_CLASS (code) == tcc_binary
> +      || code == FMA_EXPR)
>      {
>        if (is_gimple_assign (stmt)
>  	  && TREE_CODE_CLASS (code) == tcc_comparison)
> --- gcc/testsuite/g++.dg/opt/pr79396.C.jj	2017-02-25 09:20:03.608706718 +0100
> +++ gcc/testsuite/g++.dg/opt/pr79396.C	2017-02-25 09:20:03.607706732 +0100
> @@ -0,0 +1,13 @@
> +// PR middle-end/79396
> +// { dg-do compile }
> +// { dg-options "-fnon-call-exceptions -O2" }
> +// { dg-additional-options "-mfma" { target i?86-*-* x86_64-*-* } }
> +
> +struct A { A (); ~A (); };
> +
> +float
> +foo (float x)
> +{
> +  A a;
> +  return __builtin_pow (x, 2) + 2;
> +}
> 
> 
> 	Jakub
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)