Index: config/aarch64/aarch64.c
===================================================================
--- config/aarch64/aarch64.c	(revision 240461)
+++ config/aarch64/aarch64.c	(working copy)
@@ -7351,7 +7351,8 @@
       break;
     }
 
-  if (dump_file && (dump_flags & TDF_DETAILS))
+  if (dump_file
+      && flag_aarch64_verbose_cost)
     fprintf (dump_file,
       "\nFailed to cost RTX.  Assuming default cost.\n");
 
@@ -7367,7 +7368,8 @@
 {
   bool result = aarch64_rtx_costs (x, mode, outer, param, cost, speed);
 
-  if (dump_file && (dump_flags & TDF_DETAILS))
+  if (dump_file
+      && flag_aarch64_verbose_cost)
     {
       print_rtl_single (dump_file, x);
       fprintf (dump_file, "\n%s cost: %d (%s)\n",
Index: config/aarch64/aarch64.opt
===================================================================
--- config/aarch64/aarch64.opt	(revision 240461)
+++ config/aarch64/aarch64.opt	(working copy)
@@ -167,3 +167,7 @@
 Enable the division approximation.  Enabling this reduces
 precision of division results to about 16 bits for
 single precision and to 32 bits for double precision.
+
+mverbose-cost-dump
+Common Var(flag_aarch64_verbose_cost)
+Enables verbose cost model dummping in the debug dump files.