Quoting Kaz Kojima <kkoj...@rr.iij4u.or.jp>:
It seems that find_reloads calls set_unique_reg_note for
a USE insn.
That's true, and it is by design.
This use of set_unique_reg_note is a bit debatable - add_reg_note
should do just fine there.
OTOH keeping this as it is, and keeping set_unique_reg_note accepting USE
in this case, seems more conservative for stage3.
2011-11-07 Joern Rennecke <joern.renne...@embecosm.com>
* emit-rtl.c (set_unique_reg_note): Don't add notes that disagree
with the SET_DEST of INSN.
Index: trunk/gcc/emit-rtl.c
===================================================================
--- trunk/gcc/emit-rtl.c (revision 181122)
+++ trunk/gcc/emit-rtl.c (working copy)
@@ -4951,8 +4951,32 @@
rtx
set_unique_reg_note (rtx insn, enum reg_note kind, rtx datum)
{
- rtx note = find_reg_note (insn, kind, NULL_RTX);
+ rtx set, note;
+ enum machine_mode mode;
+ /* Sometimes the value is calculated with some SUBREG tricks, so the
+ SET_DEST of INSN ends up with a different mode then DATUM. */
+ set = single_set (insn);
+ if (set)
+ {
+ mode = GET_MODE (SET_DEST (set));
+ /* If DATUM is too narrow, we can't make it fit. */
+ if ((GET_MODE (datum) != VOIDmode || GET_MODE_CLASS (mode) != MODE_INT)
+ && GET_MODE_SIZE (mode) > GET_MODE_SIZE (GET_MODE (datum)))
+ return NULL_RTX;
+ if (GET_MODE (datum) != VOIDmode && GET_MODE (datum) != mode)
+ {
+ /* Adjust DATUM to the SET_DEST. */
+ datum = simplify_gen_subreg (mode, datum, GET_MODE (datum), 0);
+ if (!datum)
+ return NULL_RTX;
+ }
+ }
+ else /* Reload uses USEs with REG_EQUAL notes attached to keep track of
+ reload inhertiance opportunities. */
+ gcc_assert (PATTERN (insn) == USE && reload_in_progress);
+ note = find_reg_note (insn, kind, NULL_RTX);
+
switch (kind)
{
case REG_EQUAL:
