re PR target/26726 (-fivopts producing out of bounds array refs)

2006-05-01  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/26726
	* tree-ssa-loop-ivopts.c (idx_find_step): Mark source of the
	problem ...
	(find_interesting_uses_address): ... we work around here
	by folding INDIRECT_REFs in the substituted base.

	* g++.dg/tree-ssa/ivopts-1.C: New testcase.

From-SVN: r113414

gcc/ChangeLog

+2006-05-01  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/26726
+	* tree-ssa-loop-ivopts.c (idx_find_step): Mark source of the
+	problem ...
+	(find_interesting_uses_address): ... we work around here
+	by folding INDIRECT_REFs in the substituted base.
+
 2006-05-01  Diego Novillo  <dnovillo@redhat.com>
 
 	* omp-low.c (dump_omp_region): Add newlines.

gcc/testsuite/ChangeLog

+2006-05-01  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/26726
+	* g++.dg/tree-ssa/ivopts-1.C: New testcase.
+
 2006-04-30  Roger Sayle  <roger@eyesopen.com>
 
 	* gcc.dg/Woverflow-1.c: New test case.

gcc/testsuite/g++.dg/tree-ssa/ivopts-1.C

+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-ivopts" } */
+
+struct Foo {
+  Foo() : s(1) {}
+  int s;
+};
+void foo(Foo&);
+void bar(void)
+{
+  Foo x[4];
+  foo(x[0]);
+}
+
+/* { dg-final { scan-tree-dump-not "-&x" "ivopts" } } */
+/* { dg-final { scan-tree-dump-not "offset: -4B" "ivopts" { xfail i?86-*-* x86_64-*-* } } } */
+/* { dg-final { scan-tree-dump-not "&x\\\[5\\\]" "ivopts" { xfail i?86-*-* x86_64-*-* } } } */
+/* { dg-final { cleanup-tree-dump "ivopts" } } */

gcc/tree-ssa-loop-ivopts.c

@@ -1376,6 +1376,9 @@ idx_find_step (tree base, tree *idx, void *data)
   if (!iv)
     return false;
 
+  /* XXX  We produce for a base of *D42 with iv->base being &x[0]
+	  *&x[0], which is not folded and does not trigger the
+	  ARRAY_REF path below.  */
   *idx = iv->base;
 
   if (!iv->step)
@@ -1547,6 +1550,17 @@ find_interesting_uses_address (struct ivopts_data *data, tree stmt, tree *op_p)
       gcc_assert (TREE_CODE (base) != MISALIGNED_INDIRECT_REF);
 
       base = build_fold_addr_expr (base);
+
+      /* Substituting bases of IVs into the base expression might
+	 have caused folding opportunities.  */
+      if (TREE_CODE (base) == ADDR_EXPR)
+	{
+	  tree *ref = &TREE_OPERAND (base, 0);
+	  while (handled_component_p (*ref))
+	    ref = &TREE_OPERAND (*ref, 0);
+	  if (TREE_CODE (*ref) == INDIRECT_REF)
+	    *ref = fold_indirect_ref (*ref);
+	}
     }
 
   civ = alloc_iv (base, step);