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Re: [PATCH] Fix unwinding through noreturn functions
- From: Andreas Schwab <schwab at suse dot de>
- To: Richard Henderson <rth at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Sat, 03 Jul 2004 15:27:52 +0200
- Subject: Re: [PATCH] Fix unwinding through noreturn functions
- References: <jen02niexa.fsf@sykes.suse.de> <20040629232126.GB21323@redhat.com>
Richard Henderson <rth@redhat.com> writes:
> I think maybe it would be better to introduce an attribute that
> is true for all patterns that expand to nothing.
Regtested again on ia64-linux.
2004-07-03 Andreas Schwab <schwab@suse.de>
* config/ia64/ia64.md: Define new attribute "empty".
(prologue_use, nop_x, insn_group_barrier): Set it.
* config/ia64/ia64.c (ia64_reorg): When looking for trailing call
skip over "empty" insns.
Index: gcc/config/ia64/ia64.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/ia64/ia64.c,v
retrieving revision 1.293
diff -u -p -a -r1.293 ia64.c
--- gcc/config/ia64/ia64.c 2 Jul 2004 04:53:30 -0000 1.293
+++ gcc/config/ia64/ia64.c 3 Jul 2004 11:37:09 -0000
@@ -7666,11 +7666,12 @@ ia64_reorg (void)
insn = get_last_insn ();
if (! INSN_P (insn))
insn = prev_active_insn (insn);
- if (GET_CODE (insn) == INSN
- && GET_CODE (PATTERN (insn)) == UNSPEC_VOLATILE
- && XINT (PATTERN (insn), 1) == UNSPECV_INSN_GROUP_BARRIER)
- {
- saw_stop = 1;
+ /* Skip over insns that expand to nothing. */
+ while (GET_CODE (insn) == INSN && get_attr_empty (insn) == EMPTY_YES)
+ {
+ if (GET_CODE (PATTERN (insn)) == UNSPEC_VOLATILE
+ && XINT (PATTERN (insn), 1) == UNSPECV_INSN_GROUP_BARRIER)
+ saw_stop = 1;
insn = prev_active_insn (insn);
}
if (GET_CODE (insn) == CALL_INSN)
Index: gcc/config/ia64/ia64.md
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/ia64/ia64.md,v
retrieving revision 1.129
diff -u -p -a -r1.129 ia64.md
--- gcc/config/ia64/ia64.md 27 Apr 2004 05:19:49 -0000 1.129
+++ gcc/config/ia64/ia64.md 3 Jul 2004 11:37:09 -0000
@@ -154,6 +154,10 @@
(define_attr "predicable" "no,yes" (const_string "yes"))
+;; Empty. True iff this insn does not generate any code.
+
+(define_attr "empty" "no,yes" (const_string "no"))
+
;; DFA descriptions of ia64 processors used for insn scheduling and
@@ -5425,7 +5429,8 @@
""
""
[(set_attr "itanium_class" "ignore")
- (set_attr "predicable" "no")])
+ (set_attr "predicable" "no")
+ (set_attr "empty" "yes")])
;; Allocate a new register frame.
@@ -5592,7 +5597,8 @@
[(const_int 5)]
""
""
- [(set_attr "itanium_class" "nop_x")])
+ [(set_attr "itanium_class" "nop_x")
+ (set_attr "empty" "yes")])
;; The following insn will be never generated. It is used only by
;; insn scheduler to change state before advancing cycle.
@@ -5624,7 +5630,8 @@
""
";;"
[(set_attr "itanium_class" "stop_bit")
- (set_attr "predicable" "no")])
+ (set_attr "predicable" "no")
+ (set_attr "empty" "yes")])
(define_expand "trap"
[(trap_if (const_int 1) (const_int 0))]
Andreas.
--
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany
Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."