re PR tree-optimization/27755 (PRE confused by control flow)

2006-11-14  Daniel Berlin  <dberlin@dberlin.org>

	Fix PR tree-optimization/27755

	* tree-ssa-pre.c: Update comments.
	(bb_bitmap_sets): Add pa_in and  deferred member.
	(BB_DEFERRED): New macro.
	(maximal_set): New variable.
	(pre_stats): Add pa_insert member.
	(bitmap_set_and): Short circuit orig == dest.
	(bitmap_set_subtract_values): New function.
	(bitmap_set_contains_expr): Ditto.
	(translate_vuses_through_block): Add phiblock argument.
	(dependent_clean): New function.
	(compute_antic_aux): Update for maximal_set changes.
	(compute_partial_antic_aux): New function.
	(compute_antic): Handle partial anticipation.
	(do_partial_partial_insertion): New function.
	(insert_aux): Handle partial anticipation.
	(add_to_sets): Add to maximal set.
	(compute_avail): Ditto.
	(init_pre): Initialize maximal_set.
	(execute_pre): Do partial anticipation if -O3+.

From-SVN: r118821

gcc/ChangeLog

+2006-11-14  Daniel Berlin  <dberlin@dberlin.org>
+
+	Fix PR tree-optimization/27755
+
+	* tree-ssa-pre.c: Update comments.
+	(bb_bitmap_sets): Add pa_in and  deferred member.
+	(BB_DEFERRED): New macro.
+	(maximal_set): New variable.
+	(pre_stats): Add pa_insert member.
+	(bitmap_set_and): Short circuit orig == dest.
+	(bitmap_set_subtract_values): New function.
+	(bitmap_set_contains_expr): Ditto.
+	(translate_vuses_through_block): Add phiblock argument.
+	(dependent_clean): New function.
+	(compute_antic_aux): Update for maximal_set changes.
+	(compute_partial_antic_aux): New function.
+	(compute_antic): Handle partial anticipation.
+	(do_partial_partial_insertion): New function.
+	(insert_aux): Handle partial anticipation.
+	(add_to_sets): Add to maximal set.
+	(compute_avail): Ditto.
+	(init_pre): Initialize maximal_set.
+	(execute_pre): Do partial anticipation if -O3+.
+
 2006-11-14  Paolo Bonzini  <bonzini@gnu.org>
 
 	PR rtl-optimization/29798

gcc/testsuite/gcc.dg/tree-ssa/ssa-pre-16.c

+/* { dg-do compile } */ 
+/* { dg-options "-O2 -fdump-tree-pre-stats -std=c99" } */
+int foo(int k, int *x)
+{
+  int j=0;
+  int res = 0;
+  /* We should pull res = *x all the way out of the do-while */
+  do {
+    for (int n=0;n<3;++n);
+    res = *x;
+  }  while (++j<k);
+  return res;
+}
+/* { dg-final { scan-tree-dump-times "Eliminated: 1" 1 "pre"} } */
+/* { dg-final { cleanup-tree-dump "pre" } } */