re PR tree-optimization/63962 ([x86] Code pessimization after r217213)

2014-11-20  Richard Biener  <rguenther@suse.de>

	PR middle-end/63962
	* match.pd ((p +p off1) +p off2 -> (p +p (off1 + off2))):
	Guard with single-use operand 0.

	* gcc.dg/tree-ssa/forwprop-30.c: New testcase.

From-SVN: r217828

gcc/ChangeLog

+2014-11-20  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/63962
+	* match.pd ((p +p off1) +p off2 -> (p +p (off1 + off2))):
+	Guard with single-use operand 0.
+
 2014-11-20   Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/63677

gcc/match.pd

@@ -370,8 +370,9 @@ along with GCC; see the file COPYING3.  If not see
 
 /* Associate (p +p off1) +p off2 as (p +p (off1 + off2)).  */
 (simplify
-  (pointer_plus (pointer_plus @0 @1) @3)
-  (pointer_plus @0 (plus @1 @3)))
+  (pointer_plus (pointer_plus@2 @0 @1) @3)
+  (if (TREE_CODE (@2) != SSA_NAME || has_single_use (@2))
+   (pointer_plus @0 (plus @1 @3))))
 
 /* Pattern match
      tem1 = (long) ptr1;

gcc/testsuite/ChangeLog

+2014-11-20  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/63962
+	* gcc.dg/tree-ssa/forwprop-30.c: New testcase.
+
 2014-11-20   Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/63677

gcc/testsuite/gcc.dg/tree-ssa/forwprop-30.c

+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-optimized" } */
+
+int *p;
+int *foo (int *q, int i, int j)
+{
+  p = q + i;
+  return p + j;
+}
+
+/* We shouldn't associate (q + i) + j to q + (i + j) here as we
+   need q + i as well.  */
+
+/* { dg-final { scan-tree-dump-times "\\+" 2 "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */