introduce TDF_compare_debug, omit OBJ_TYPE_REF casts with it

for  gcc/ChangeLog

	* dumpfile.h (TDF_COMPARE_DEBUG): New.
	* final.c (rest_of_clean_state): Set it for the
	-fcompare-debug dump.
	* tree-pretty-print.c (dump_generic_node): Omit OBJ_TYPE_REF
	class when TDF_COMPARE_DEBUG is set.

From-SVN: r254751

gcc/ChangeLog

 2017-11-15  Alexandre Oliva <aoliva@redhat.com>
 
+	* dumpfile.h (TDF_COMPARE_DEBUG): New.
+	* final.c (rest_of_clean_state): Set it for the
+	-fcompare-debug dump.
+	* tree-pretty-print.c (dump_generic_node): Omit OBJ_TYPE_REF
+	class when TDF_COMPARE_DEBUG is set.
+
 	* dwarf2out.c (gen_producer_string): Discard
 	OPT_fcompare_debug.
 

gcc/dumpfile.h

@@ -93,6 +93,7 @@ enum dump_kind
 #define MSG_NOTE		 (1 << 24)  /* general optimization info */
 #define MSG_ALL		(MSG_OPTIMIZED_LOCATIONS | MSG_MISSED_OPTIMIZATION \
 			 | MSG_NOTE)
+#define TDF_COMPARE_DEBUG (1 << 25)	/* Dumping for -fcompare-debug.  */
 
 
 /* Value of TDF_NONE is used just for bits filtered by TDF_KIND_MASK.  */

gcc/final.c

@@ -4629,7 +4629,7 @@ rest_of_clean_state (void)
 	{
 	  flag_dump_noaddr = flag_dump_unnumbered = 1;
 	  if (flag_compare_debug_opt || flag_compare_debug)
-	    dump_flags |= TDF_NOUID;
+	    dump_flags |= TDF_NOUID | TDF_COMPARE_DEBUG;
 	  dump_function_header (final_output, current_function_decl,
 				dump_flags);
 	  final_insns_dump_p = true;

gcc/tree-pretty-print.c

@@ -2760,7 +2760,15 @@ dump_generic_node (pretty_printer *pp, tree node, int spc, dump_flags_t flags,
       pp_string (pp, "OBJ_TYPE_REF(");
       dump_generic_node (pp, OBJ_TYPE_REF_EXPR (node), spc, flags, false);
       pp_semicolon (pp);
-      if (!(flags & TDF_SLIM) && virtual_method_call_p (node))
+      /* We omit the class type for -fcompare-debug because we may
+	 drop TYPE_BINFO early depending on debug info, and then
+	 virtual_method_call_p would return false, whereas when
+	 TYPE_BINFO is preserved it may still return true and then
+	 we'd print the class type.  Compare tree and rtl dumps for
+	 libstdc++-prettyprinters/shared_ptr.cc with and without -g,
+	 for example, at occurrences of OBJ_TYPE_REF.  */
+      if (!(flags & (TDF_SLIM | TDF_COMPARE_DEBUG))
+	  && virtual_method_call_p (node))
 	{
 	  pp_string (pp, "(");
 	  dump_generic_node (pp, obj_type_ref_class (node), spc, flags, false);