swap_tree_operands does not handle swapping operands in
a_1 = x_2 + 1; very well as it keeps the use operand for
x_2 pointing to its old slot and thus 1 after it finished.
That's of course bad as no user of swap_tree_operands feels
the need to update the statement - swap_tree_operands is
after all exactly to avoid updating the statement (and
eventually disrupting the operand list).
Fixed, thus.
Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
Richard.
2011-09-09 Richard Guenther <rguent...@suse.de>
* tree-ssa-operands.c (swap_tree_operands): Always adjust
existing operand positions.
Index: gcc/tree-ssa-operands.c
===================================================================
--- gcc/tree-ssa-operands.c (revision 178719)
+++ gcc/tree-ssa-operands.c (working copy)
@@ -1149,7 +1149,8 @@ swap_tree_operands (gimple stmt, tree *e
/* If the operand cache is active, attempt to preserve the relative
positions of these two operands in their respective immediate use
- lists. */
+ lists by adjusting their use pointer to point to the new
+ operand position. */
if (ssa_operands_active () && op0 != op1)
{
use_optype_p use0, use1, ptr;
@@ -1170,14 +1171,12 @@ swap_tree_operands (gimple stmt, tree *e
break;
}
- /* If both uses don't have operand entries, there isn't much we can do
- at this point. Presumably we don't need to worry about it. */
- if (use0 && use1)
- {
- tree *tmp = USE_OP_PTR (use1)->use;
- USE_OP_PTR (use1)->use = USE_OP_PTR (use0)->use;
- USE_OP_PTR (use0)->use = tmp;
- }
+ /* And adjust their location to point to the new position of the
+ operand. */
+ if (use0)
+ USE_OP_PTR (use0)->use = exp1;
+ if (use1)
+ USE_OP_PTR (use1)->use = exp0;
}
/* Now swap the data. */
