On Wed, Jan 11, 2012 at 10:28:55AM +0100, Eric Botcazou wrote:
> > IMHO reordering the notes in the chain would be even more work than this.
>
> Can't we just move down the lines
>
> if (ecf_flags & ECF_NORETURN)
> add_reg_note (call_insn, REG_NORETURN, const0_rtx);
>
> if (ecf_flags & ECF_RETURNS_TWICE)
> {
> add_reg_note (call_insn, REG_SETJMP, const0_rtx);
> cfun->calls_setjmp = 1;
> }
>
> in emit_call_1 with a big comment explaining why the ECF_NORETURN note should
> come first?
I'd find that very fragile. E.g. distribute_notes itself reverses the order
of all notes, and for no REG_NOTES I think we rely on any ordering.
Anyway, here is an (untested) variant of the patch that puts the
REG_NORETURN note in first in distribute_notes:
2012-01-11 Jakub Jelinek <[email protected]>
PR bootstrap/51796
* combine.c (distribute_notes): If i3 is a noreturn call,
allow old_size to be equal to args_size and make sure the
noreturn call gets REG_ARGS_SIZE note.
* expr.c (fixup_args_size_notes): Put REG_ARGS_SIZE notes
on noreturn calls even when the delta is 0.
--- gcc/combine.c.jj 2011-12-09 15:21:20.000000000 +0100
+++ gcc/combine.c 2012-01-11 09:37:40.199961939 +0100
@@ -13281,8 +13281,28 @@ distribute_notes (rtx notes, rtx from_in
if (!noop_move_p (i3))
{
int old_size, args_size = INTVAL (XEXP (note, 0));
+ /* fixup_args_size_notes looks at REG_NORETURN note,
+ so ensure the note is placed there first. */
+ if (CALL_P (i3))
+ {
+ rtx *np;
+ for (np = &next_note; *np; np = &XEXP (*np, 1))
+ if (REG_NOTE_KIND (*np) == REG_NORETURN)
+ {
+ rtx n = *np;
+ *np = XEXP (n, 1);
+ XEXP (n, 1) = REG_NOTES (i3);
+ REG_NOTES (i3) = n;
+ break;
+ }
+ }
old_size = fixup_args_size_notes (PREV_INSN (i3), i3, args_size);
- gcc_assert (old_size != args_size);
+ /* emit_call_1 adds for !ACCUMULATE_OUTGOING_ARGS
+ REG_ARGS_SIZE note to all noreturn calls, allow that here. */
+ gcc_assert (old_size != args_size
+ || (CALL_P (i3)
+ && !ACCUMULATE_OUTGOING_ARGS
+ && find_reg_note (i3, REG_NORETURN, NULL_RTX)));
}
break;
--- gcc/expr.c.jj 2012-01-02 17:36:53.000000000 +0100
+++ gcc/expr.c 2012-01-11 09:30:08.549680295 +0100
@@ -3642,9 +3642,11 @@ mem_autoinc_base (rtx mem)
(1) One or more auto-inc style memory references (aka pushes),
(2) One or more addition/subtraction with the SP as destination,
(3) A single move insn with the SP as destination,
- (4) A call_pop insn.
+ (4) A call_pop insn,
+ (5) Noreturn call insns if !ACCUMULATE_OUTGOING_ARGS.
- Insns in the sequence that do not modify the SP are ignored.
+ Insns in the sequence that do not modify the SP are ignored,
+ except for noreturn calls.
The return value is the amount of adjustment that can be trivially
verified, via immediate operand or auto-inc. If the adjustment
@@ -3789,7 +3791,12 @@ fixup_args_size_notes (rtx prev, rtx las
this_delta = find_args_size_adjust (insn);
if (this_delta == 0)
- continue;
+ {
+ if (!CALL_P (insn)
+ || ACCUMULATE_OUTGOING_ARGS
+ || find_reg_note (insn, REG_NORETURN, NULL_RTX) == NULL_RTX)
+ continue;
+ }
gcc_assert (!saw_unknown);
if (this_delta == HOST_WIDE_INT_MIN)
--- gcc/testsuite/gcc.dg/pr51796.c.jj 2012-01-10 16:43:00.494803970 +0100
+++ gcc/testsuite/gcc.dg/pr51796.c 2012-01-10 16:43:00.494803970 +0100
@@ -0,0 +1,15 @@
+/* PR bootstrap/51796 */
+/* { dg-do compile } */
+/* { dg-options "-Os -fno-omit-frame-pointer -fno-tree-dominator-opts
-fno-tree-fre -fno-tree-pre" } */
+
+typedef void (*entry_func) (void) __attribute__ ((noreturn));
+extern entry_func entry_addr;
+static void bsd_boot_entry (void)
+{
+ stop ();
+}
+void bsd_boot (void)
+{
+ entry_addr = (entry_func) bsd_boot_entry;
+ (*entry_addr) ();
+}
Jakub
