re PR tree-optimization/77646 (GCC Segfault with -O3)

2016-09-20  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/77646
	* tree-ssa-sccvn.c (visit_reference_op_call): Always value-number
	a VDEF.

	* gcc.dg/torture/pr77646.c: New testcase.

From-SVN: r240261

gcc/ChangeLog

+2016-09-20  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/77646
+	* tree-ssa-sccvn.c (visit_reference_op_call): Always value-number
+	a VDEF.
+
 2016-09-20  Tamar Christina  <tamar.christina@arm.com>
 
 	* config/aarch64/arm_neon.h: Add gnu_inline and artificial

gcc/testsuite/ChangeLog

+2016-09-20  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/77646
+	* gcc.dg/torture/pr77646.c: New testcase.
+
 2016-09-19  Bernd Edlinger  <bernd.edlinger@hotmail.de>
 
 	PR c++/77434

gcc/testsuite/gcc.dg/torture/pr77646.c

+/* { dg-do compile } */
+
+struct e {
+    int (*f)();
+    void (*g)();
+} * c;
+int a;
+void *h();
+typedef struct { struct e j; } k;
+int l() { return a; }
+const struct e b = {l};
+void m()
+{
+  k *d = h();
+  d->j = b;
+  c = (struct e *)d;
+  struct e *i = c;
+  if (i->f(c))
+    while (i->f(c))
+      i->g();
+}

gcc/tree-ssa-sccvn.c

@@ -3470,6 +3470,10 @@ visit_reference_op_call (tree lhs, gcall *stmt)
     {
       if (vnresult->result_vdef && vdef)
 	changed |= set_ssa_val_to (vdef, vnresult->result_vdef);
+      else if (vdef)
+	/* If the call was discovered to be pure or const reflect
+	   that as far as possible.  */
+	changed |= set_ssa_val_to (vdef, vuse_ssa_val (gimple_vuse (stmt)));
 
       if (!vnresult->result && lhs)
 	vnresult->result = lhs;