[BRIGFE] allow controlling strict aliasing from cmd line

From-SVN: r259948

gcc/brig/ChangeLog

 2018-05-04  Pekka Jääskeläinen  <pekka.jaaskelainen@parmance.com>
 
+	* brig/brig-lang.c: Allow controlling strict aliasing from
+	cmd line.
+
+2018-05-04  Pekka Jääskeläinen  <pekka.jaaskelainen@parmance.com>
+
 	* brig/brigfrontend/brig-code-entry-handler.cc: The modulo in
 	ID computation should not be needed.
 

gcc/brig/brig-lang.c

@@ -167,9 +167,15 @@ brig_langhook_post_options (const char **pfilename ATTRIBUTE_UNUSED)
   if (flag_excess_precision_cmdline == EXCESS_PRECISION_DEFAULT)
     flag_excess_precision_cmdline = EXCESS_PRECISION_STANDARD;
 
-  /* gccbrig casts pointers around like crazy, TBAA produces
-     broken code if not force disabling it.  */
-  flag_strict_aliasing = 0;
+  /* gccbrig casts pointers around like crazy, TBAA might produce broken
+     code if not disabling it by default.  Some PRM conformance tests such
+     as prm/core/memory/ordinary/ld/ld_u16 fail currently with strict
+     aliasing (to fix).  It can be enabled from the command line for cases
+     that are known not to break the C style aliasing requirements.  */
+  if (!global_options_set.x_flag_strict_aliasing)
+    flag_strict_aliasing = 0;
+  else
+    flag_strict_aliasing = global_options.x_flag_strict_aliasing;
 
   /* Returning false means that the backend should be used.  */
   return false;