We're updating REG_DEAD notes in regrename.c, but it seems this is for
historical reasons only. As far as I can tell, every pass that needs
such notes recomputes them with df_note_add_problem/df_analyze, and the
following patch bootstrapped and tested successfully on i686-linux (some
random libmudflap failures mentioned previously), with the following
change to ensure it's tested:
+++ gcc/config/i386/i386.c (working copy)
@@ -5099,6 +5099,9 @@ static const struct default_options ix86
#ifdef INSN_SCHEDULING
{ OPT_LEVELS_ALL, OPT_fschedule_insns, NULL, 0 },
#endif
+#ifdef INSN_SCHEDULING
+ { OPT_LEVELS_2_PLUS, OPT_frename_registers, NULL, 1 },
+#endif
Ok?
Bernd
* regrename.c (do_replace): Don't update notes.
Index: gcc/regrename.c
===================================================================
--- gcc/regrename.c (revision 174842)
+++ gcc/regrename.c (working copy)
@@ -432,7 +432,6 @@ do_replace (struct du_head *head, int re
{
struct du_chain *chain;
unsigned int base_regno = head->regno;
- bool found_note = false;
gcc_assert (! DEBUG_INSN_P (head->first->insn));
@@ -446,46 +445,15 @@ do_replace (struct du_head *head, int re
INSN_VAR_LOCATION_LOC (chain->insn) = gen_rtx_UNKNOWN_VAR_LOC ();
else
{
- rtx note;
-
*chain->loc = gen_raw_REG (GET_MODE (*chain->loc), reg);
if (regno >= FIRST_PSEUDO_REGISTER)
ORIGINAL_REGNO (*chain->loc) = regno;
REG_ATTRS (*chain->loc) = attr;
REG_POINTER (*chain->loc) = reg_ptr;
-
- for (note = REG_NOTES (chain->insn); note; note = XEXP (note, 1))
- {
- enum reg_note kind = REG_NOTE_KIND (note);
- if (kind == REG_DEAD || kind == REG_UNUSED)
- {
- rtx reg = XEXP (note, 0);
- gcc_assert (HARD_REGISTER_P (reg));
-
- if (REGNO (reg) == base_regno)
- {
- found_note = true;
- if (kind == REG_DEAD
- && reg_set_p (*chain->loc, chain->insn))
- remove_note (chain->insn, note);
- else
- XEXP (note, 0) = *chain->loc;
- break;
- }
- }
- }
}
df_insn_rescan (chain->insn);
}
- if (!found_note)
- {
- /* If the chain's first insn is the same as the last, we should have
- found a REG_UNUSED note. */
- gcc_assert (head->first->insn != head->last->insn);
- if (!reg_set_p (*head->last->loc, head->last->insn))
- add_reg_note (head->last->insn, REG_DEAD, *head->last->loc);
- }
}
