[PATCH] doloop_optimize miscompiles openssl
Franz Sirl
Franz.Sirl-kernel@lauterbach.com
Sun Sep 24 15:07:00 GMT 2000
On Sun, 24 Sep 2000, Franz Sirl wrote:
> * doloop.c (doloop_modify): Prevent delete_insn() from deleting too much.
> Use loop->top as target for the new JUMP insn.
>
> Index: gcc/doloop.c
> ===================================================================
> RCS file: /cvs/gcc/egcs/gcc/doloop.c,v
> retrieving revision 1.2
> diff -u -p -r1.2 doloop.c
> --- gcc/doloop.c 2000/08/14 20:55:11 1.2
> +++ gcc/doloop.c 2000/09/24 17:38:16
> @@ -416,11 +416,14 @@ doloop_modify (loop, iterations, iterati
> }
>
> /* Discard original jump to continue loop. The original compare
> - result may still be live, so it cannot be discarded explicitly. */
> + result may still be live, so it cannot be discarded explicitly.
> + Don't delete too much, increment the use count of the target label.
> */ + LABEL_NUSES (JUMP_LABEL (jump_insn))++;
> delete_insn (jump_insn);
> + LABEL_NUSES (JUMP_LABEL (jump_insn))--;
>
> - /* Emit the label that will delimit the start of the loop. */
> - emit_label_after (start_label, loop->start);
> + /* Emit the label that will delimit the top of the loop. */
> + emit_label_after (start_label, loop->top);
> LABEL_NUSES (start_label)++;
>
> counter_reg = XEXP (condition, 0);
The patch needs a small refinement, but then passes the bootstrap&testsuite
and fixes the openssl miscompilation. On to fixing the next openssl
miscompilation :-(.
Franz.
* doloop.c (doloop_modify): Prevent delete_insn() from deleting too much.
Prefer loop->top over loop->start as target for the new JUMP insn.
Index: gcc/doloop.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/doloop.c,v
retrieving revision 1.2
diff -u -p -r1.2 doloop.c
--- doloop.c 2000/08/14 20:55:11 1.2
+++ doloop.c 2000/09/24 22:00:04
@@ -416,11 +416,14 @@ doloop_modify (loop, iterations, iterati
}
/* Discard original jump to continue loop. The original compare
- result may still be live, so it cannot be discarded explicitly. */
+ result may still be live, so it cannot be discarded explicitly.
+ Don't delete too much, increment the use count of the target label. */
+ LABEL_NUSES (JUMP_LABEL (jump_insn))++;
delete_insn (jump_insn);
+ LABEL_NUSES (JUMP_LABEL (jump_insn))--;
- /* Emit the label that will delimit the start of the loop. */
- emit_label_after (start_label, loop->start);
+ /* Emit the label that will delimit the top of the loop. */
+ emit_label_after (start_label, loop->top ? loop->top : loop->start);
LABEL_NUSES (start_label)++;
counter_reg = XEXP (condition, 0);
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