Fix discriminators of gimple PHI arguments

while gimple PHI itself does not have locations, the arguments does and they
can be used to determine count of edges in CFG.  Assign_discriminators already
knows how to handle goto_locus and PHI args should be handled same way as
done by this patch.

Bootstrapped/regtested x86_64-linux, comitted.

gcc/ChangeLog:

	* auto-profile.cc (function_instance::match): Sanity check
	that gimple PHI has no location.
	* tree-cfg.cc (assign_discriminators): Also remap locations
	of gimple PHI arguments.

Author: janhubicka

gcc/auto-profile.cc

@@ -1371,10 +1371,13 @@ function_instance::match (cgraph_node *node,
 	  gphi *phi = gpi.phi ();
 	  inline_stack stack;
 
+	  /* We do not assign discriminators to PHI nodes.
+	     In case we every start using them, we wil need to
+	     update tree-cfg.cc::assign_discriminators.  */
+	  gcc_assert (gimple_location (phi) == UNKNOWN_LOCATION);
 	  get_inline_stack_in_node (gimple_location (phi), &stack, node);
 	  count_info *info = lookup_count (gimple_location (phi), stack, node);
-	  if (info)
-	    counts.add (info);
+	  gcc_assert (!info);
 	  dump_stmt (phi, info, NULL, stack);
 	  counts.add (info);
 	  for (edge e : bb->succs)

gcc/tree-cfg.cc

@@ -1132,8 +1132,8 @@ assign_discriminators (void)
     {
       location_t prev_loc = UNKNOWN_LOCATION, prev_replacement = UNKNOWN_LOCATION;
       /* Traverse the basic block, if two function calls within a basic block
-	are mapped to the same line, assign a new discriminator because a call
-	stmt could be a split point of a basic block.  */
+	 are mapped to the same line, assign a new discriminator because a call
+	 stmt could be a split point of a basic block.  */
       for (gimple_stmt_iterator gsi = gsi_start_bb (bb);
 	   !gsi_end_p (gsi); gsi_next (&gsi))
 	{
@@ -1149,8 +1149,8 @@ assign_discriminators (void)
 	      prev_replacement = assign_discriminator (loc, bb_id, map);
 	      gimple_set_location (stmt, prev_replacement);
 	    }
-	  /* Break basic blocks after each call.  This is requires so each
-	     call site has unque discriminator.
+	  /* Break basic blocks after each call.  This is required so each
+	     call site has unique discriminator.
 	     More correctly, we can break after each statement that can possibly
 	     terinate execution of the basic block, but for auto-profile this
 	     precision is probably not useful.  */
@@ -1160,16 +1160,27 @@ assign_discriminators (void)
 	      bb_id++;
 	    }
 	}
-      /* IF basic block has multiple sucessors, consdier every edge as a separate
-	 block.  */
+      /* If basic block has multiple sucessors, consdier every edge as a
+	 separate block.  */
       if (!single_succ_p (bb))
 	bb_id++;
       for (edge e : bb->succs)
-	if (e->goto_locus != UNKNOWN_LOCATION)
-	  {
+	{
+	  if (e->goto_locus != UNKNOWN_LOCATION)
 	    e->goto_locus = assign_discriminator (e->goto_locus, bb_id, map);
-	    bb_id++;
-	  }
+	  for (gphi_iterator gpi = gsi_start_phis (bb);
+	       !gsi_end_p (gpi); gsi_next (&gpi))
+	    {
+	      gphi *phi = gpi.phi ();
+	      location_t phi_loc
+		= gimple_phi_arg_location_from_edge (phi, e);
+	      if (phi_loc == UNKNOWN_LOCATION)
+		continue;
+	      gimple_phi_arg_set_location
+		(phi, e->dest_idx, assign_discriminator (phi_loc, bb_id, map));
+	    }
+	   bb_id++;
+	}
       bb_id++;
     }