http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47559
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |wrong-code
Status|UNCONFIRMED |NEW
Last reconfirmed| |2011.02.01 12:03:49
CC| |rakdver at gcc dot gnu.org
Component|middle-end |tree-optimization
Ever Confirmed|0 |1
--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-02-01
12:03:49 UTC ---
LIM produces
void foo(int*) (int * k)
Eh tree:
1 must_not_throw
{
int k__lsm.1;
<bb 2>:
k__lsm.1_4 = MEM[(int *)k_1(D)];
<bb 3>:
[MNT 1] k__lsm.1_5 = 0;
<bb 4>:
goto <bb 3>;
}
failing to move the EH info. I think it should just give up here - it
tries to, but only if loop exits via EH edges appear - which is not
the case for must-not-throw. There is also no exit in that endless loop
anyway - which shows the transform isn't valid as if *k points to
readonly memory the testcase now will fail to trap as the store never
happens. Which means this is wrong-code as well (should we simply
not do store-motion for loops without exits?). Thus, the following
would fix the wrong-code issue (but probably not the ICE in a more
generalized test):
Index: gcc/tree-ssa-loop-im.c
===================================================================
--- gcc/tree-ssa-loop-im.c (revision 169434)
+++ gcc/tree-ssa-loop-im.c (working copy)
@@ -2368,6 +2368,9 @@ loop_suitable_for_sm (struct loop *loop
unsigned i;
edge ex;
+ if (VEC_empty (edge, exits))
+ return false;
+
FOR_EACH_VEC_ELT (edge, exits, i, ex)
if (ex->flags & (EDGE_ABNORMAL | EDGE_EH))
return false;
I am testing that change now.
