see.c (see_def_extension_not_merged): Use copy_rtx_if_shared to avoid invalid sharing.

2008-05-28  Rafael Espindola  <espindola@google.com>

	* see.c (see_def_extension_not_merged): Use copy_rtx_if_shared to avoid
	invalid sharing.

2008-05-28  Rafael Espindola  <espindola@google.com>

	* gcc.dg/20080528-1.c: New test.

From-SVN: r136115

gcc/ChangeLog

+2008-05-28  Rafael Espindola  <espindola@google.com>
+
+	* see.c (see_def_extension_not_merged): Use copy_rtx_if_shared to avoid
+	invalid sharing.
+
 2008-05-28  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/36339

gcc/see.c

@@ -2554,6 +2554,17 @@ see_def_extension_not_merged (struct see_ref_s *curr_ref_s, rtx def_se)
 
   /* The manipulation succeeded.  Store the new manipulated reference.  */
 
+  /* It is possible for dest_reg to appear multiple times in ref_copy. In this
+     case, ref_copy now has invalid sharing. Copying solves the problem.
+     We don't use copy_rtx as an optimization for the common case (no sharing).
+     We can't just use copy_rtx_if_shared since it does nothing on INSNs.
+     Another possible solution would be to make validate_replace_rtx_1
+     public and use it instead of replace_rtx. */
+  reset_used_flags (PATTERN (ref_copy));
+  reset_used_flags (REG_NOTES (ref_copy));
+  PATTERN (ref_copy) = copy_rtx_if_shared (PATTERN (ref_copy));
+  REG_NOTES (ref_copy) = copy_rtx_if_shared (REG_NOTES (ref_copy));
+
   /* Try to simplify the new manipulated insn.  */
   validate_simplify_insn (ref_copy);
 

gcc/testsuite/ChangeLog

+2008-05-28  Rafael Espindola  <espindola@google.com>
+
+	* gcc.dg/20080528-1.c: New test.
+
 2008-05-28  Arnaud Charlet  <charlet@adacore.com>
 
 	* gnat.dg/old_errors.adb, gnat.dg/deep_old.adb: Adjust.

gcc/testsuite/gcc.dg/20080528-1.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -fsee" } */
+
+unsigned long g(int a, int b) {
+  return a / b;
+}
+unsigned long f(long int a) {
+  return g(a, 1<<13);
+}