------- Comment #23 from spark at gcc dot gnu dot org 2007-07-03 19:41 -------
This patch:
diff -r 29a7055e69fc gcc/df-scan.c
--- a/gcc/df-scan.c Sun Jun 24 00:16:55 2007 +0000
+++ b/gcc/df-scan.c Tue Jul 03 12:38:41 2007 -0700
@@ -2763,6 +2763,12 @@ df_def_record_1 (struct df_collection_re
|| (GET_CODE (dst) == SUBREG && REG_P (SUBREG_REG (dst))))
df_ref_record (collection_rec,
dst, loc, bb, insn, DF_REF_REG_DEF, flags);
+
+ /* We want to keep sp alive everywhere - by making all
+ writes to sp also use of sp. */
+ if (REG_P (dst) && REGNO (dst) == STACK_POINTER_REGNUM)
+ df_ref_record (collection_rec,
+ dst, NULL, bb, insn, DF_REF_REG_USE, flags);
}
also fixes the problem, by treating all defs of SP as a use of SP.
This patch essentially makes SP alive everywhere.
Also, this would create less number of unnecessary df_ref's
(since presumably there are less number of stack defs than
MEM_LOAD/STORE w/ hard frame pointer reference).
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32475
