https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100960
--- Comment #4 from Stefan Schulze Frielinghaus <stefansf at linux dot ibm.com>
---
I really like the idea of enhancing cselib since there is a chance that other
passes might profit from it, too. The following patch fixes the initial
reported problem:
diff --git a/gcc/cselib.cc b/gcc/cselib.cc
index 6a5609786fa..64b6996a299 100644
--- a/gcc/cselib.cc
+++ b/gcc/cselib.cc
@@ -1569,6 +1569,25 @@ new_cselib_val (unsigned int hash, machine_mode mode,
rtx x)
e->locs = 0;
e->next_containing_mem = 0;
+ scalar_int_mode int_mode;
+ if (REG_P (x) && is_int_mode (mode, &int_mode) && REG_VALUES (REGNO (x)) !=
NULL
+ && (!cselib_current_insn || !DEBUG_INSN_P (cselib_current_insn)))
+ {
+ rtx copy = shallow_copy_rtx (x);
+ scalar_int_mode narrow_mode;
+ FOR_EACH_MODE_UNTIL(narrow_mode, int_mode)
+ {
+ PUT_MODE_RAW (copy, narrow_mode);
+ cselib_val *v = cselib_lookup (copy, narrow_mode, 0, VOIDmode);
+ if (v)
+ {
+ rtx sub = lowpart_subreg (narrow_mode, e->val_rtx, int_mode);
+ if (sub)
+ new_elt_loc_list (v, sub);
+ }
+ }
+ }
+
if (dump_file && (dump_flags & TDF_CSELIB))
{
fprintf (dump_file, "cselib value %u:%u ", e->uid, hash);
So I get the subvalue relation between 5:5 and 14:14 (was initially 15:15 but
changed meanwhile due to new GCC version)
(value/u:SI 5:5 @0x4f906e0/0x4f80730)
locs:
from insn 17 (subreg:SI (value/u:DI 14:14 @0x4f907b8/0x4f808e0) 4)
from insn 1 (value/u:SI 6:263 @0x4f906f8/0x4f80760)
from insn 1 (entry_value:SI (reg:SI 2 %r2 [ xD.2274 ]))
no addrs
