fix handling of mapped and their location

So when we using the newly mapped location, we should check if
it is not unknown location and if so just use the original location.
Note this is a latent bug in remove_forwarder_block_with_phi code too.

This fixes gcc.dg/uninit-pr40635.c when doing more mergephi.

gcc/ChangeLog:

	* tree-cfg.cc (copy_phi_arg_into_existing_phi): Use the original location
	if the mapped location is unknown.

Signed-off-by: Andrew Pinski <andrew.pinski@oss.qualcomm.com>

diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
index 5a082eee5243c2584e344e2a874f6d91fc1a46b7..1d20e6ab6ba429eb9fbfed741dba93e11cbd93f3 100644 (file)
--- a/gcc/tree-cfg.cc
+++ b/gcc/tree-cfg.cc
@@ -6828,7 +6828,10 @@ copy_phi_arg_into_existing_phi (edge src_e, edge tgt_e, bool use_map)
              if (val == old_arg)
                {
                  val = new_arg;
-                 locus = redirect_edge_var_map_location (vm);
+                 location_t locus1 = redirect_edge_var_map_location (vm);
+                 /* Don't remove the location if we remap one does not have one.  */
+                 if (locus1 != UNKNOWN_LOCATION)
+                   locus = locus1;
                  break;
                }
            }