re PR tree-optimization/23911 (Failure to propagate constants from a const…

re PR tree-optimization/23911 (Failure to propagate constants from a const initializer for _Complex)

gcc/
	PR tree-optimization/23911
	* tree-ssa-ccp.c (fold_const_aggregate_ref): Handle REALPART_EXPR
	and IMAGPART_EXPR too.

testsuite/
	* gcc.dg/pr23911.c: New test.

From-SVN: r104771

gcc/ChangeLog

+2005-09-29  Steven Bosscher  <stevenb@suse.de>
+
+	PR tree-optimization/23911
+	* tree-ssa-ccp.c (fold_const_aggregate_ref): Handle REALPART_EXPR
+	and IMAGPART_EXPR too.
+
 2005-09-28  Mark Mitchell  <mark@codesourcery.com>
 
 	PR 17886

gcc/testsuite/ChangeLog

+2005-09-29  Steven Bosscher  <stevenb@suse.de>
+
+	* gcc.dg/pr23911.c: New test.
+
 2005-09-28  Mark Mitchell  <mark@codesourcery.com>
 
 	* g++.dg/opt/pr19650.C: Use -w -fpermissive.

gcc/testsuite/gcc.dg/pr23911.c

+/* This was a missed optimization in tree constant propagation
+   that CSE would catch later on.  */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-store_ccp" } */
+
+double _Complex *a; 
+const double _Complex b[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}; 
+ 
+void 
+test (void) 
+{ 
+  a[0] = b[0] + b[1]; 
+  a[1] = b[0] + b[1]; 
+  return; 
+} 
+
+/* After store_ccp, there should not be any assignments from real or
+   imaginary parts anymore.  The constants should be loaded from b and
+   propagated into the elements of a.  */
+/* { dg-final { scan-tree-dump-times "= CR" 0 "store_ccp" } } */
+/* { dg-final { scan-tree-dump-times "= CI" 0 "store_ccp" } } */
+/* { dg-final { cleanup-tree-dump "store_ccp" } } */

gcc/tree-ssa-ccp.c

@@ -1045,6 +1045,15 @@ fold_const_aggregate_ref (tree t)
 	  return cval;
       break;
 
+    case REALPART_EXPR:
+    case IMAGPART_EXPR:
+      {
+	tree c = fold_const_aggregate_ref (TREE_OPERAND (t, 0));
+	if (c && TREE_CODE (c) == COMPLEX_CST)
+	  return fold_build1 (TREE_CODE (t), TREE_TYPE (t), c);
+	break;
+      }
+    
     default:
       break;
     }