re PR tree-optimization/51396 (ICE: verify_flow_info failed: BB 4 can not throw…

re PR tree-optimization/51396 (ICE: verify_flow_info failed: BB 4 can not throw but has an EH edge with -O2 -fnon-call-exceptions -mfma4)

	PR tree-optimization/51396
	* tree-ssa-math-opts.c (convert_mult_to_fma): Don't optimize
	if MUL_RESULT has zero uses.

	* g++.dg/opt/pr51396.C: New test.

From-SVN: r182028

gcc/ChangeLog

 2011-12-05  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/51396
+	* tree-ssa-math-opts.c (convert_mult_to_fma): Don't optimize
+	if MUL_RESULT has zero uses.
+
 	PR debug/51410
 	* c-decl.c (pop_scope): Don't add DECL_EXTERNAL decls
 	for debug info if scope is file_scope.

gcc/testsuite/ChangeLog

 2011-12-05  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/51396
+	* g++.dg/opt/pr51396.C: New test.
+
 	PR debug/51410
 	* gcc.dg/debug/dwarf2/pr51410.c: New test.
 

gcc/testsuite/g++.dg/opt/pr51396.C

+// PR tree-optimization/51396
+// { dg-do compile }
+// { dg-options "-O2 -fnon-call-exceptions -mfma" }
+// { dg-options "-O2 -fnon-call-exceptions -mfma" { target i?86-*-* x86_64-*-* } }
+
+double baz (double) throw ();
+
+struct C
+{
+  C (double d = 0.0) : c (d) {}
+  double c;
+};
+
+static inline void
+foo (double x, const C &y)
+{
+  x ? (y.c * baz (x)) : (C (), y);
+}
+
+void
+bar (double x, C y)
+{
+  foo (x, y);
+}

gcc/tree-ssa-math-opts.c

@@ -2429,6 +2429,12 @@ convert_mult_to_fma (gimple mul_stmt, tree op1, tree op2)
   if (optab_handler (fma_optab, TYPE_MODE (type)) == CODE_FOR_nothing)
     return false;
 
+  /* If the multiplication has zero uses, it is kept around probably because
+     of -fnon-call-exceptions.  Don't optimize it away in that case,
+     it is DCE job.  */
+  if (has_zero_uses (mul_result))
+    return false;
+
   /* Make sure that the multiplication statement becomes dead after
      the transformation, thus that all uses are transformed to FMAs.
      This means we assume that an FMA operation has the same cost