Remove the REG_EQUAL note if we don't know its invariant status.

gcc/

2010-03-18  Steven Bosscher  <steven@gcc.gnu.org>
	    Eric Botcazou  <ebotcazou@adacore.com>

	PR rtl-optimization/43360
	* loop-invariant.c (move_invariant_reg): Remove the REG_EQUAL
	note if we don't know its invariant status.

gcc/testsuite/

2010-03-18  H.J. Lu  <hongjiu.lu@intel.com>

	PR rtl-optimization/43360
	* gcc.dg/torture/pr43360.c: New.

From-SVN: r157539

gcc/ChangeLog

+2010-03-18  Steven Bosscher  <steven@gcc.gnu.org>
+	    Eric Botcazou  <ebotcazou@adacore.com>
+
+	PR rtl-optimization/43360
+	* loop-invariant.c (move_invariant_reg): Remove the REG_EQUAL
+	note if we don't know its invariant status.
+
 2010-03-18  Michael Matz  <matz@suse.de>
 
 	PR tree-optimization/43402

gcc/loop-invariant.c

@@ -1423,14 +1423,16 @@ move_invariant_reg (struct loop *loop, unsigned invno)
       emit_insn_after (gen_move_insn (dest, reg), inv->insn);
       reorder_insns (inv->insn, inv->insn, BB_END (preheader));
 
-      /* If there is a REG_EQUAL note on the insn we just moved, and
-	 insn is in a basic block that is not always executed, the note
-	 may no longer be valid after we move the insn.
-	 Note that uses in REG_EQUAL notes are taken into account in
-	 the computation of invariants.  Hence it is safe to retain the
-	 note even if the note contains register references.  */
-      if (! inv->always_executed
-	  && (note = find_reg_note (inv->insn, REG_EQUAL, NULL_RTX)))
+      /* If there is a REG_EQUAL note on the insn we just moved, and the
+	 insn is in a basic block that is not always executed or the note
+	 contains something for which we don't know the invariant status,
+	 the note may no longer be valid after we move the insn.  Note that
+	 uses in REG_EQUAL notes are taken into account in the computation
+	 of invariants, so it is safe to retain the note even if it contains
+	 register references for which we know the invariant status.  */
+      if ((note = find_reg_note (inv->insn, REG_EQUAL, NULL_RTX))
+	  && (!inv->always_executed
+	      || !check_maybe_invariant (XEXP (note, 0))))
 	remove_note (inv->insn, note);
     }
   else

gcc/testsuite/ChangeLog

+2010-03-18  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR rtl-optimization/43360
+	* gcc.dg/torture/pr43360.c: New.
+
 2010-03-18  Michael Matz  <matz@suse.de>
 
 	PR tree-optimization/43402

gcc/testsuite/gcc.dg/torture/pr43360.c

+/* { dg-do run } */
+
+int l_5_5_2 = 4;
+int g_3[1][1];
+
+void func_1 (void)
+{
+  for (g_3[0][0] = 1; g_3[0][0] < 8; g_3[0][0] += 7) {
+    int *l_6 = &g_3[0][0];
+    *l_6 = l_5_5_2;
+  }
+}
+
+int main (void)
+{
+  func_1 ();
+  if (g_3[0][0] != 11)
+      __builtin_abort ();
+  return 0;
+}