combine: Use TDF_DETAILS for "can't combine" dump prints

Some people use the -fdump-rtl-combine dumps (instead of the -da or
-fdump-rtl-combine-all dump), but the "Can't combine iN into iM"
messages do not make any sense if the failed combine attempts are not
printed otherwise.  So let's change that.


	* combine.c (try_combine): Do not print "Can't combine" messages unless
	printing failed combination attempts.

From-SVN: r268453

gcc/ChangeLog

+2019-02-01  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	* combine.c (try_combine): Do not print "Can't combine" messages unless
+	printing failed combination attempts.
+
 2019-02-01  Martin Jambor  <mjambor@suse.cz>
 
 	PR hsa/87863

gcc/combine.c

@@ -3078,21 +3078,21 @@ try_combine (rtx_insn *i3, rtx_insn *i2, rtx_insn *i1, rtx_insn *i0,
   /* Verify that I2 and maybe I1 and I0 can be combined into I3.  */
   if (!can_combine_p (i2, i3, i0, i1, NULL, NULL, &i2dest, &i2src))
     {
-      if (dump_file)
+      if (dump_file && (dump_flags & TDF_DETAILS))
 	fprintf (dump_file, "Can't combine i2 into i3\n");
       undo_all ();
       return 0;
     }
   if (i1 && !can_combine_p (i1, i3, i0, NULL, i2, NULL, &i1dest, &i1src))
     {
-      if (dump_file)
+      if (dump_file && (dump_flags & TDF_DETAILS))
 	fprintf (dump_file, "Can't combine i1 into i3\n");
       undo_all ();
       return 0;
     }
   if (i0 && !can_combine_p (i0, i3, NULL, NULL, i1, i2, &i0dest, &i0src))
     {
-      if (dump_file)
+      if (dump_file && (dump_flags & TDF_DETAILS))
 	fprintf (dump_file, "Can't combine i0 into i3\n");
       undo_all ();
       return 0;