Hi!
When a VALUE contains already some constant location, it will be always
preferable to expressing it by some other expression - const (or some
similar reverse operation), so we just should point at adding the
reverse_op.
This fixes the testcase from the PR on mips64-linux, bootstrapped/regtested
on x86_64-linux and i686-linux, ok for trunk?
2012-01-26 Jakub Jelinek <ja...@redhat.com>
PR debug/52001
* var-tracking.c (reverse_op): Don't add any reverse operation
if V already has any constant locations.
--- gcc/var-tracking.c.jj 2012-01-23 18:23:45.000000000 +0100
+++ gcc/var-tracking.c 2012-01-26 16:37:20.110049563 +0100
@@ -5298,6 +5298,7 @@ reverse_op (rtx val, const_rtx expr, rtx
{
rtx src, arg, ret;
cselib_val *v;
+ struct elt_loc_list *l;
enum rtx_code code;
if (GET_CODE (expr) != SET)
@@ -5333,6 +5334,14 @@ reverse_op (rtx val, const_rtx expr, rtx
if (!v || !cselib_preserved_value_p (v))
return;
+ /* Adding a reverse op isn't useful if V already has an always valid
+ location. Ignore ENTRY_VALUE, while it is always constant, we should
+ prefer non-ENTRY_VALUE locations whenever possible. */
+ for (l = v->locs; l; l = l->next)
+ if (CONSTANT_P (l->loc)
+ && (GET_CODE (l->loc) != CONST || !references_value_p (l->loc, 0)))
+ return;
+
switch (GET_CODE (src))
{
case NOT:
Jakub
