re PR middle-end/71581 (ICE on valid code on x86_64-linux-gnu with…

re PR middle-end/71581 (ICE on valid code on x86_64-linux-gnu with -Wuninitialized (Segmentation fault))

	PR middle-end/71581
	* tree-ssa-uninit.c (warn_uninit): If EXPR and VAR are NULL,
	see if T isn't anonymous SSA_NAME with COMPLEX_EXPR created
	for conversion of scalar user var to complex type and use the
	underlying SSA_NAME_VAR in that case.  If EXPR is still NULL,
	punt.

	* gcc.dg/pr71581.c: New test.

From-SVN: r237621

gcc/ChangeLog

 2016-06-20  Jakub Jelinek  <jakub@redhat.com>
 
+	PR middle-end/71581
+	* tree-ssa-uninit.c (warn_uninit): If EXPR and VAR are NULL,
+	see if T isn't anonymous SSA_NAME with COMPLEX_EXPR created
+	for conversion of scalar user var to complex type and use the
+	underlying SSA_NAME_VAR in that case.  If EXPR is still NULL,
+	punt.
+
 	PR rtl-optimization/71591
 	* toplev.c (toplev::run_self_tests): If no_backend, complain and
 	don't run any tests.

gcc/testsuite/ChangeLog

 2016-06-20  Jakub Jelinek  <jakub@redhat.com>
 
+	PR middle-end/71581
+	* gcc.dg/pr71581.c: New test.
+
 	PR rtl-optimization/71591
 	* gcc.dg/cpp/pr71591.c: New test.
 

gcc/testsuite/gcc.dg/pr71581.c

+/* PR middle-end/71581 */
+/* { dg-do compile } */
+/* { dg-options "-Wuninitialized" } */
+
+_Complex float
+f1 (void)
+{
+  float x;
+  return x;	/* { dg-warning "is used uninitialized in this function" } */
+}
+
+_Complex double
+f2 (void)
+{
+  double x;
+  return x;	/* { dg-warning "is used uninitialized in this function" } */
+}
+
+_Complex int
+f3 (void)
+{
+  int x;
+  return x;	/* { dg-warning "is used uninitialized in this function" } */
+}

gcc/tree-ssa-uninit.c

@@ -131,6 +131,29 @@ warn_uninit (enum opt_code wc, tree t, tree expr, tree var,
   if (!has_undefined_value_p (t))
     return;
 
+  /* Anonymous SSA_NAMEs shouldn't be uninitialized, but ssa_undefined_value_p
+     can return true if the def stmt of anonymous SSA_NAME is COMPLEX_EXPR
+     created for conversion from scalar to complex.  Use the underlying var of
+     the COMPLEX_EXPRs real part in that case.  See PR71581.  */
+  if (expr == NULL_TREE
+      && var == NULL_TREE
+      && SSA_NAME_VAR (t) == NULL_TREE
+      && is_gimple_assign (SSA_NAME_DEF_STMT (t))
+      && gimple_assign_rhs_code (SSA_NAME_DEF_STMT (t)) == COMPLEX_EXPR)
+    {
+      tree v = gimple_assign_rhs1 (SSA_NAME_DEF_STMT (t));
+      if (TREE_CODE (v) == SSA_NAME
+	  && has_undefined_value_p (v)
+	  && zerop (gimple_assign_rhs2 (SSA_NAME_DEF_STMT (t))))
+	{
+	  expr = SSA_NAME_VAR (v);
+	  var = expr;
+	}
+    }
+
+  if (expr == NULL_TREE)
+    return;
+
   /* TREE_NO_WARNING either means we already warned, or the front end
      wishes to suppress the warning.  */
   if ((context