------- Comment #7 from dorit at il dot ibm dot com 2005-12-07 20:49 -------
(In reply to comment #6)
Can you test the attached patch?
Unfortunrately it's relative to autovect-branch, but hopefully it would easily
apply to mainline/4.1. Unbootstrapped, hardly tested...
Index: tree-vect-transform.c
===================================================================
--- tree-vect-transform.c (revision 108060)
+++ tree-vect-transform.c (working copy)
@@ -5052,12 +5069,44 @@
tree cond_expr_stmt_list = NULL_TREE;
basic_block condition_bb;
block_stmt_iterator cond_exp_bsi;
+ basic_block merge_bb;
+ basic_block new_exit_bb;
+ edge new_exit_e, e;
+ tree orig_phi, new_phi, arg;
cond_expr = vect_create_cond_for_align_checks (loop_vinfo,
&cond_expr_stmt_list);
initialize_original_copy_tables ();
nloop = loop_version (loops, loop, cond_expr, &condition_bb, true);
free_original_copy_tables();
+
+ /** Loop versioning violets an assumption we try to maintain during
+ vectorization - that the loop exit block has a single predecessor.
+ After versioning, the exit block of both loop versions is the same
+ basic block (i.e. it has two predecessors). Just in order to simplify
+ following transformations in the vectorizer, we fix this situation
+ here by adding a new (empty) block on the exit-edge of the loop,
+ with the proper loop-exit phis to maintain loop-closed-form. **/
+
+ merge_bb = loop->single_exit->dest;
+ gcc_assert (EDGE_COUNT (merge_bb->preds) == 2);
+ new_exit_bb = split_edge (loop->single_exit);
+ add_bb_to_loop (new_exit_bb, loop->outer);
+ new_exit_e = loop->single_exit;
+ e = EDGE_SUCC (new_exit_bb, 0);
+
+ for (orig_phi = phi_nodes (merge_bb); orig_phi;
+ orig_phi = PHI_CHAIN (orig_phi))
+ {
+ new_phi = create_phi_node (SSA_NAME_VAR (PHI_RESULT (orig_phi)),
+ new_exit_bb);
+ arg = PHI_ARG_DEF_FROM_EDGE (orig_phi, e);
+ add_phi_arg (new_phi, arg, new_exit_e);
+ SET_PHI_ARG_DEF (orig_phi, e->dest_idx, PHI_RESULT (new_phi));
+ }
+
+ /** end loop-exit-fixes after versioning **/
+
update_ssa (TODO_update_ssa);
cond_exp_bsi = bsi_last (condition_bb);
bsi_insert_before (&cond_exp_bsi, cond_expr_stmt_list, BSI_SAME_STMT);
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24378
