[PATCH v8 11/12] Dump reason for missing tail call into dump file

[Andi Kleen]

gcc/ChangeLog:

        * tree-tailcall.cc (maybe_error_musttail): Print reason to
        dump_file.
        (find_tail_calls): Print gimple stmt or other reasons that stop
        the search for tail calls into dump file.
---
 gcc/tree-tailcall.cc | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/gcc/tree-tailcall.cc b/gcc/tree-tailcall.cc
index a77fa1511415..f69a9ad40bda 100644
--- a/gcc/tree-tailcall.cc
+++ b/gcc/tree-tailcall.cc
@@ -442,6 +442,11 @@ maybe_error_musttail (gcall *call, const char *err)
       gimple_call_set_must_tail (call, false); /* Avoid another error.  */
       gimple_call_set_tail (call, false);
     }
+  if (dump_file)
+    {
+      print_gimple_stmt (dump_file, call, 0, TDF_SLIM);
+      fprintf (dump_file, "Cannot convert: %s\n", err);
+    }
 }
 
 /* Count succ edges for BB and return in NUM_OTHER and NUM_EH.  */
@@ -492,7 +497,12 @@ find_tail_calls (basic_block bb, struct tailcall **ret, 
bool only_musttail,
       /* Allow EH edges so that we can give a better
         error message later.  */
       if (num_other != 1)
-       return;
+       {
+         if (dump_file)
+           fprintf (dump_file, "Basic block %d has %d eh / %d other edges\n",
+                          bb->index, num_eh, num_other);
+         return;
+       }
     }
 
   bool bad_stmt = false;
@@ -537,6 +547,11 @@ find_tail_calls (basic_block bb, struct tailcall **ret, 
bool only_musttail,
       if (gimple_references_memory_p (stmt)
          || gimple_has_volatile_ops (stmt))
        {
+         if (dump_file)
+           {
+             fprintf (dump_file, "Cannot handle ");
+             print_gimple_stmt (dump_file, stmt, 0);
+           }
          bad_stmt = true;
        }
     }
-- 
2.45.2