On Fri, Mar 15, 2019 at 09:22:26AM +0100, Richard Biener wrote:
> That said, I think we can go with my patch for GCC 9 and defer a more
> complete and elaborate solution to GCC 10 (where I'd still prefer
> sth simple).
>
> What do you think?
Ok. gimple_purge_dead_abnormal_call_edges after all isn't that expensive,
it just walks over all successor edges of a bb.
Right now gimple_purge_all_dead_abnormal_call_edges is only called by
sccvn on specific bbs that do need ab cleanup, tree-inline.c calls
gimple_purge_dead_abnormal_call_edges only if it is inlining a call at the
end of a bb and tree-cfg.c calls it for const/pure calls.
In that last case, I wonder if we actually shouldn't do following, because
it makes no sense to call it for each constant/pure call in a bb when all we
care about is whether it is the last stmt that is a pure/const call.
--- gcc/tree-cfg.c.jj 2019-03-14 23:44:27.861560155 +0100
+++ gcc/tree-cfg.c 2019-03-15 09:37:15.667785016 +0100
@@ -9483,7 +9483,8 @@ execute_fixup_cfg (void)
int flags = gimple_call_flags (stmt);
if (flags & (ECF_CONST | ECF_PURE | ECF_LOOPING_CONST_OR_PURE))
{
- if (gimple_purge_dead_abnormal_call_edges (bb))
+ if (gsi_one_before_end_p (gsi)
+ && gimple_purge_dead_abnormal_call_edges (bb))
todo |= TODO_cleanup_cfg;
if (gimple_in_ssa_p (cfun))
Jakub
