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

[Jakub Jelinek <jakub@redhat.com>]

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:

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