https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106057
Bug ID: 106057
Summary: Missed stmt_can_throw_external check in
stmt_kills_ref_p
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: hubicka at gcc dot gnu.org
Target Milestone: ---
int a;
int b;
__attribute__((const))
int maybethrow()
{
if (!b)
throw(0);
return 0;
}
void
test()
{
a=1;
a=maybethrow();
a=0;
}
int
main()
{
try {
test();
}
catch(int) {
if (!a)
__builtin_abort ();
}
return 0;
}
aborts when built with -O2 while I think it should not. The bug is that
a=maybethrow()
is considered a kill which it is not since exception happens earlier.
I think we need:
diff --git a/gcc/tree-ssa-alias.cc b/gcc/tree-ssa-alias.cc
index b1e7a2d5afc..7307e386f96 100644
--- a/gcc/tree-ssa-alias.cc
+++ b/gcc/tree-ssa-alias.cc
@@ -3337,7 +3338,9 @@ stmt_kills_ref_p (gimple *stmt, ao_ref *ref)
??? We only need to care about the RHS throwing. For aggregate
assignments or similar calls and non-call exceptions the LHS
might throw as well. */
- && !stmt_can_throw_internal (cfun, stmt))
+ && !stmt_can_throw_internal (cfun, stmt)
+ && (!stmt_can_throw_external (cfun, stmt)
+ || !ref_may_alias_global_p (ref, false)))
{
tree lhs = gimple_get_lhs (stmt);
/* If LHS is literally a base of the access we are done. */
