[PTX] assembler name mangling

[Nathan Sidwell <nathan at acm dot org>]

I've committed this cleanup to use TARGET_MANGLE_DECL_ASSEMBLER_NAME rather than 
the ad-hoc solution the ptx backend currently has.   I didn't address it during 
the earlier set of cleanups as I felt there were more important things to 
address then.

I did discover an issue in langhooks, where the target name mangling hook wasn't 
being called, and led to __builtin_realloc and friends not being mangled as 
needed.  I've applied this change to langhooks as obvious.  The only other use 
of this target hook appears to be i386-mingw, where the additional call appears 
harmless.

nathan

2016-05-13  Nathan Sidwell  <nathan@acm.org>

	* config/nvptx/nvptx.c (nvptx_mangle_decl_assembler_name): New.
	(nvptx_name_replacement): Delete.
	(write_fn_proto, write_fn_proto_from_insn,
	nvptx_output_call_insn): Remove nvptx_name_replacement call.
	(TARGET_MANGLE_DECL_ASSEMBLER_NAME): Override.
	* langhooks.c (add_builtin_funcction_common): Call
	targetm.mangle_decl_assembler_name.

Index: config/nvptx/nvptx.c
===================================================================
--- config/nvptx/nvptx.c	(revision 236211)
+++ config/nvptx/nvptx.c	(working copy)
@@ -211,6 +211,31 @@ nvptx_ptx_type_from_mode (machine_mode m
     }
 }
 
+/* Return an identifier node for DECL.  Usually thee default mangled
+   name ID is useable.  Some names cannot be used directly, so prefix
+   them with __nvptx_.  */
+
+static tree
+nvptx_mangle_decl_assembler_name (tree ARG_UNUSED (decl), tree id)
+{
+  static const char *const bad_names[] =
+    {"call", "malloc", "free", "realloc", 0};
+  int ix;
+  const char *name = IDENTIFIER_POINTER (id);
+
+  for (ix = 0; bad_names[ix]; ix++)
+    if (!strcmp (bad_names[ix], name))
+      {
+	char *new_name = XALLOCAVEC (char,
+				     strlen (name) + sizeof ("__nvptx_"));
+	sprintf (new_name, "__nvptx_%s", name);
+	id = get_identifier (new_name);
+	break;
+      }
+
+  return id;
+}
+
 /* Encode the PTX data area that DECL (which might not actually be a
    _DECL) should reside in.  */
 
@@ -256,24 +281,6 @@ section_for_decl (const_tree decl)
   return section_for_sym (XEXP (DECL_RTL (CONST_CAST (tree, decl)), 0));
 }
 
-/* Check NAME for special function names and redirect them by returning a
-   replacement.  This applies to malloc, free and realloc, for which we
-   want to use libgcc wrappers, and call, which triggers a bug in ptxas.  */
-
-static const char *
-nvptx_name_replacement (const char *name)
-{
-  if (strcmp (name, "call") == 0)
-    return "__nvptx_call";
-  if (strcmp (name, "malloc") == 0)
-    return "__nvptx_malloc";
-  if (strcmp (name, "free") == 0)
-    return "__nvptx_free";
-  if (strcmp (name, "realloc") == 0)
-    return "__nvptx_realloc";
-  return name;
-}
-
 /* If MODE should be treated as two registers of an inner mode, return
    that inner mode.  Otherwise return VOIDmode.  */
 
@@ -731,13 +738,8 @@ write_fn_proto (std::stringstream &s, bo
   if (is_defn)
     /* Emit a declaration. The PTX assembler gets upset without it.   */
     name = write_fn_proto (s, false, name, decl);
-  else
-    {
-      /* Avoid repeating the name replacement.  */
-      name = nvptx_name_replacement (name);
-      if (name[0] == '*')
-	name++;
-    }
+  else if (name[0] == '*')
+    name++;
 
   write_fn_marker (s, is_defn, TREE_PUBLIC (decl), name);
 
@@ -841,7 +843,6 @@ write_fn_proto_from_insn (std::stringstr
     }
   else
     {
-      name = nvptx_name_replacement (name);
       write_fn_marker (s, false, true, name);
       s << "\t.extern .func ";
     }
@@ -1859,7 +1860,6 @@ nvptx_output_call_insn (rtx_insn *insn,
   if (decl)
     {
       const char *name = get_fnname_from_decl (decl);
-      name = nvptx_name_replacement (name);
       assemble_name (asm_out_file, name);
     }
   else
@@ -4887,6 +4887,9 @@ nvptx_goacc_reduction (gcall *call)
 #undef TARGET_NO_REGISTER_ALLOCATION
 #define TARGET_NO_REGISTER_ALLOCATION true
 
+#undef TARGET_MANGLE_DECL_ASSEMBLER_NAME
+#define TARGET_MANGLE_DECL_ASSEMBLER_NAME nvptx_mangle_decl_assembler_name
+
 #undef TARGET_ENCODE_SECTION_INFO
 #define TARGET_ENCODE_SECTION_INFO nvptx_encode_section_info
 #undef TARGET_RECORD_OFFLOAD_SYMBOL
Index: langhooks.c
===================================================================
--- langhooks.c	(revision 236208)
+++ langhooks.c	(working copy)
@@ -561,6 +561,8 @@ add_builtin_function_common (const char
   if (library_name)
     {
       tree libname = get_identifier (library_name);
+
+      libname = targetm.mangle_decl_assembler_name (decl, libname);
       SET_DECL_ASSEMBLER_NAME (decl, libname);
     }