tree_forwarder_block_p has
if (find_edge (ENTRY_BLOCK_PTR, bb))
return false;
without explanation. This test was added by you, Jeff - do you remember why?
Removing this check triggers some ICEs in the testsuite because remove_bb
(called from remove_forwarder_block) unconditionally moves labels from the
removed block to prev_bb (yuck!) - which is of course invalid if that happens
to be the entry bb. Luckily remove_forwarder_block already contains code
to do the label-move job itself - it is just conditional on seen abnormal
incoming edges. Enabling this code to run by default causes a bootstrap
comparison failure though.
--
Summary: tree_forwarder_block_p says no to first basic block
Product: gcc
Version: 4.4.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: enhancement
Priority: P3
Component: middle-end
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: rguenth at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38264
