tree-optimization/113373 - add missing LC PHIs for live operations

The following makes reduction epilogue code generation happy by properly
adding LC PHIs to the exit blocks for multiple exit vectorized loops.

Some refactoring might make the flow easier to follow but I've refrained
from doing that with this patch.

I've kept some fixes in reduction epilogue generation from the earlier
attempt fixing this PR.

	PR tree-optimization/113373
	* tree-vect-loop-manip.cc (slpeel_tree_duplicate_loop_to_edge_cfg):
	Create LC PHIs in the exit blocks where necessary.
	* tree-vect-loop.cc (vectorizable_live_operation): Do not try
	to handle missing LC PHIs.
	(find_connected_edge): Remove.
	(vect_create_epilog_for_reduction): Cleanup use of auto_vec.

	* gcc.dg/vect/vect-early-break_104-pr113373.c: New testcase.

1 files changed, 29 insertions, 5 deletions

diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
index 1477906..eacbc02 100644
--- a/gcc/tree-vect-loop-manip.cc
+++ b/gcc/tree-vect-loop-manip.cc
@@ -1696,7 +1696,8 @@ slpeel_tree_duplicate_loop_to_edge_cfg (class loop *loop, edge loop_exit,
 	      /* Check if we've already created a new phi node during edge
 		 redirection.  If we have, only propagate the value
 		 downwards in case there is no merge block.  */
-	      if (tree *res = new_phi_args.get (new_arg))
+	      tree *res;
+	      if ((res = new_phi_args.get (new_arg)))
 		{
 		  if (multiple_exits_p)
 		    new_arg = *res;
@@ -1717,7 +1718,7 @@ slpeel_tree_duplicate_loop_to_edge_cfg (class loop *loop, edge loop_exit,
 		  /* Similar to the single exit case, If we have an existing
 		     LCSSA variable thread through the original value otherwise
 		     skip it and directly use the final value.  */
-		  if (tree *res = new_phi_args.get (tmp_arg))
+		  if ((res = new_phi_args.get (tmp_arg)))
 		    new_arg = *res;
 		  else if (!virtual_operand_p (new_arg))
 		    new_arg = tmp_arg;
@@ -1728,9 +1729,20 @@ slpeel_tree_duplicate_loop_to_edge_cfg (class loop *loop, edge loop_exit,
 
 	      /* Otherwise, main loop exit should use the final iter value.  */
 	      if (multiple_exits_p)
-		SET_PHI_ARG_DEF_ON_EDGE (lcssa_phi,
-					 single_succ_edge (main_loop_exit_block),
-					 new_arg);
+		{
+		  /* Create a LC PHI if it doesn't already exist.  */
+		  if (!virtual_operand_p (new_arg) && !res)
+		    {
+		      tree new_def = copy_ssa_name (new_arg);
+		      gphi *lc_phi
+			= create_phi_node (new_def, main_loop_exit_block);
+		      SET_PHI_ARG_DEF (lc_phi, 0, new_arg);
+		      new_arg = new_def;
+		    }
+		  SET_PHI_ARG_DEF_ON_EDGE (lcssa_phi,
+					   single_succ_edge (main_loop_exit_block),
+					   new_arg);
+		}
 	      else
 		SET_PHI_ARG_DEF_ON_EDGE (lcssa_phi, loop_exit, new_arg);
 
@@ -1766,6 +1778,18 @@ slpeel_tree_duplicate_loop_to_edge_cfg (class loop *loop, edge loop_exit,
 		      if (vphi)
 			alt_arg = gimple_phi_result (vphi);
 		    }
+		  /* For other live args we didn't create LC PHI nodes.
+		     Do so here.  */
+		  else
+		    {
+		      tree alt_def = copy_ssa_name (alt_arg);
+		      gphi *lc_phi
+			= create_phi_node (alt_def, alt_loop_exit_block);
+		      for (unsigned i = 0; i < gimple_phi_num_args (lc_phi);
+			   ++i)
+			SET_PHI_ARG_DEF (lc_phi, i, alt_arg);
+		      alt_arg = alt_def;
+		    }
 		  edge main_e = single_succ_edge (alt_loop_exit_block);
 		  SET_PHI_ARG_DEF_ON_EDGE (to_phi, main_e, alt_arg);
 		}