Re: [Patch/cfgexpand]: also consider assembler_name to call expand_main_function

[Tristan Gingold <gingold@adacore.com>]

On Mar 15, 2012, at 10:37 AM, Richard Guenther wrote:

> On Wed, 14 Mar 2012, Tristan Gingold wrote:
[…]

> 
> Well.  To make this work in LTO the "main" function (thus, the program
> entry point) should be marked at cgraph level and all users of
> MAIN_NAME_P should instead check a flag on the cgraph node.
> 
>> Will write a predicate in tree.[ch].
> 
> Please instead transition "main-ness" to the graph.

Hi,

here is the patch I wrote.  Does it match what you had in mind ?

main_identifier_node is now set in tree.c

I haven't changed MAIN_NAME_P uses in c-decl.c and cp/decl.c (obviously).
I haven't yet checked beyond simple build.

Tristan.

diff --git a/gcc/ada/gcc-interface/trans.c b/gcc/ada/gcc-interface/trans.c
index 89f5438..c575e97 100644
--- a/gcc/ada/gcc-interface/trans.c
+++ b/gcc/ada/gcc-interface/trans.c
@@ -622,8 +622,6 @@ gigi (Node_Id gnat_root, int max_gnat_node, int number_name ATTRIBUTE_UNUSED,
 		       integer_type_node, NULL_TREE, true, false, true, false,
 		       NULL, Empty);
 
-  main_identifier_node = get_identifier ("main");
-
   /* Install the builtins we might need, either internally or as
      user available facilities for Intrinsic imports.  */
   gnat_install_builtins ();
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index b83f45b..5d05d8a 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -5094,8 +5094,6 @@ c_common_nodes_and_builtins (void)
   if (!flag_preprocess_only)
     c_define_builtins (va_list_ref_type_node, va_list_arg_type_node);
 
-  main_identifier_node = get_identifier ("main");
-
   /* Create the built-in __null node.  It is important that this is
      not shared.  */
   null_node = make_node (INTEGER_CST);
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index bd21169..7a7a774 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -4513,9 +4513,8 @@ gimple_expand_cfg (void)
 
   /* If this function is `main', emit a call to `__main'
      to run global initializers, etc.  */
-  if (DECL_NAME (current_function_decl)
-      && MAIN_NAME_P (DECL_NAME (current_function_decl))
-      && DECL_FILE_SCOPE_P (current_function_decl))
+  if (DECL_FILE_SCOPE_P (current_function_decl)
+      && cgraph_main_function_p (cgraph_get_node (current_function_decl)))
     expand_main_function ();
 
   /* Initialize the stack_protect_guard field.  This must happen after the
diff --git a/gcc/cgraph.c b/gcc/cgraph.c
index 9cc3690..528fd19 100644
--- a/gcc/cgraph.c
+++ b/gcc/cgraph.c
@@ -2766,7 +2766,7 @@ cgraph_propagate_frequency_1 (struct cgraph_node *node, void *data)
 	  /* It makes sense to put main() together with the static constructors.
 	     It will be executed for sure, but rest of functions called from
 	     main are definitely not at startup only.  */
-	  if (MAIN_NAME_P (DECL_NAME (edge->caller->decl)))
+	  if (cgraph_main_function_p (edge->caller))
 	    d->only_called_at_startup = 0;
           d->only_called_at_exit &= edge->caller->only_called_at_exit;
 	}
diff --git a/gcc/cgraph.h b/gcc/cgraph.h
index 191364c..4db3417 100644
--- a/gcc/cgraph.h
+++ b/gcc/cgraph.h
@@ -101,6 +101,9 @@ struct GTY(()) cgraph_local_info {
 
   /* True if the function may enter serial irrevocable mode.  */
   unsigned tm_may_enter_irr : 1;
+
+  /* True if the function is the program entry point (main in C).  */
+  unsigned main_function : 1;
 };
 
 /* Information about the function that needs to be computed globally
@@ -790,6 +793,13 @@ cgraph_next_function_with_gimple_body (struct cgraph_node *node)
   return NULL;
 }
 
+/* Return true iff NODE is the main function (main in C).  */
+static inline bool
+cgraph_main_function_p (struct cgraph_node *node)
+{
+  return node->local.main_function;
+}
+
 /* Walk all functions with body defined.  */
 #define FOR_EACH_FUNCTION_WITH_GIMPLE_BODY(node) \
    for ((node) = cgraph_first_function_with_gimple_body (); (node); \
diff --git a/gcc/cgraphunit.c b/gcc/cgraphunit.c
index 516f187..4a59f63 100644
--- a/gcc/cgraphunit.c
+++ b/gcc/cgraphunit.c
@@ -346,6 +346,10 @@ cgraph_finalize_function (tree decl, bool nested)
   notice_global_symbol (decl);
   node->local.finalized = true;
   node->lowered = DECL_STRUCT_FUNCTION (decl)->cfg != NULL;
+  node->local.main_function =
+    DECL_FILE_SCOPE_P (decl)
+    && ((!DECL_ASSEMBLER_NAME_SET_P (decl) && MAIN_NAME_P (DECL_NAME (decl)))
+	|| decl_assembler_name_equal (decl, main_identifier_node));
 
   if (cgraph_decide_is_function_needed (node, decl))
     cgraph_mark_needed_node (node);
diff --git a/gcc/config/i386/cygming.h b/gcc/config/i386/cygming.h
index 2eccda9..8ac169e 100644
--- a/gcc/config/i386/cygming.h
+++ b/gcc/config/i386/cygming.h
@@ -360,7 +360,8 @@ do {						\
 
 #undef PROFILE_HOOK
 #define PROFILE_HOOK(LABEL)						\
-  if (MAIN_NAME_P (DECL_NAME (current_function_decl)))			\
+  if (DECL_FILE_SCOPE_P (current_function_decl)				\
+      && cgraph_main_function_p (cgraph_get_node (current_function_decl))) \
     {									\
       emit_call_insn (gen_rtx_CALL (VOIDmode,				\
 	gen_rtx_MEM (FUNCTION_MODE,					\
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 78a366e..5a3a712 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -9509,9 +9509,8 @@ ix86_minimum_incoming_stack_boundary (bool sibcall)
   /* Stack at entrance of main is aligned by runtime.  We use the
      smallest incoming stack boundary. */
   if (incoming_stack_boundary > MAIN_STACK_BOUNDARY
-      && DECL_NAME (current_function_decl)
-      && MAIN_NAME_P (DECL_NAME (current_function_decl))
-      && DECL_FILE_SCOPE_P (current_function_decl))
+      && DECL_FILE_SCOPE_P (current_function_decl)
+      && cgraph_main_function_p (cgraph_get_node (current_function_decl)))
     incoming_stack_boundary = MAIN_STACK_BOUNDARY;
 
   return incoming_stack_boundary;
diff --git a/gcc/config/pdp11/pdp11.c b/gcc/config/pdp11/pdp11.c
index 42e3af0..aa38903 100644
--- a/gcc/config/pdp11/pdp11.c
+++ b/gcc/config/pdp11/pdp11.c
@@ -240,7 +240,9 @@ pdp11_expand_prologue (void)
 
   /* If we are outputting code for main, the switch FPU to the
      right mode if TARGET_FPU.  */
-  if (MAIN_NAME_P (DECL_NAME (current_function_decl)) && TARGET_FPU)
+  if (TARGET_FPU
+      && DECL_FILE_SCOPE_P (current_function_decl)
+      && cgraph_main_function_p (cgraph_get_node (current_function_decl)))
     {
       emit_insn (gen_setd ());
       emit_insn (gen_seti ());
diff --git a/gcc/fortran/trans-decl.c b/gcc/fortran/trans-decl.c
index 8a1dd2e..6a1a494 100644
--- a/gcc/fortran/trans-decl.c
+++ b/gcc/fortran/trans-decl.c
@@ -4922,7 +4922,6 @@ create_main_function (tree fndecl)
   tmp =  build_function_type_list (integer_type_node, integer_type_node,
 				   build_pointer_type (pchar_type_node),
 				   NULL_TREE);
-  main_identifier_node = get_identifier ("main");
   ftn_main = build_decl (input_location, FUNCTION_DECL,
       			 main_identifier_node, tmp);
   DECL_EXTERNAL (ftn_main) = 0;
diff --git a/gcc/ipa-split.c b/gcc/ipa-split.c
index 9dddf39..595330e 100644
--- a/gcc/ipa-split.c
+++ b/gcc/ipa-split.c
@@ -1409,7 +1409,7 @@ execute_split_functions (void)
 	fprintf (dump_file, "Not splitting: noreturn/malloc function.\n");
       return 0;
     }
-  if (MAIN_NAME_P (DECL_NAME (current_function_decl)))
+  if (cgraph_main_function_p (node))
     {
       if (dump_file)
 	fprintf (dump_file, "Not splitting: main function.\n");
diff --git a/gcc/ipa.c b/gcc/ipa.c
index 388291a..f9dc42d 100644
--- a/gcc/ipa.c
+++ b/gcc/ipa.c
@@ -639,7 +639,7 @@ cgraph_externally_visible_p (struct cgraph_node *node,
   else if (!whole_program)
     return true;
 
-  if (MAIN_NAME_P (DECL_NAME (node->decl)))
+  if (cgraph_main_function_p (node))
     return true;
 
   return false;
diff --git a/gcc/lto-cgraph.c b/gcc/lto-cgraph.c
index 5e899bc..34bcc55 100644
--- a/gcc/lto-cgraph.c
+++ b/gcc/lto-cgraph.c
@@ -502,6 +502,7 @@ lto_output_node (struct lto_simple_output_block *ob, struct cgraph_node *node,
   bp_pack_value (&bp, node->local.versionable, 1);
   bp_pack_value (&bp, node->local.can_change_signature, 1);
   bp_pack_value (&bp, node->local.redefined_extern_inline, 1);
+  bp_pack_value (&bp, node->local.main_function, 1);
   bp_pack_value (&bp, node->needed, 1);
   bp_pack_value (&bp, node->address_taken, 1);
   bp_pack_value (&bp, node->abstract_and_needed, 1);
@@ -904,6 +905,7 @@ input_overwrite_node (struct lto_file_decl_data *file_data,
   node->local.versionable = bp_unpack_value (bp, 1);
   node->local.can_change_signature = bp_unpack_value (bp, 1);
   node->local.redefined_extern_inline = bp_unpack_value (bp, 1);
+  node->local.main_function = bp_unpack_value (bp, 1);
   node->needed = bp_unpack_value (bp, 1);
   node->address_taken = bp_unpack_value (bp, 1);
   node->abstract_and_needed = bp_unpack_value (bp, 1);
diff --git a/gcc/lto/lto-lang.c b/gcc/lto/lto-lang.c
index 999db8b..a44a35f 100644
--- a/gcc/lto/lto-lang.c
+++ b/gcc/lto/lto-lang.c
@@ -1137,13 +1137,6 @@ lto_init (void)
   /* Create the basic integer types.  */
   build_common_tree_nodes (flag_signed_char, /*short_double=*/false);
 
-  /* The global tree for the main identifier is filled in by
-     language-specific front-end initialization that is not run in the
-     LTO back-end.  It appears that all languages that perform such
-     initialization currently do so in the same way, so we do it here.  */
-  if (main_identifier_node == NULL_TREE)
-    main_identifier_node = get_identifier ("main");
-
   /* In the C++ front-end, fileptr_type_node is defined as a variant
      copy of of ptr_type_node, rather than ptr_node itself.  The
      distinction should only be relevant to the front-end, so we
diff --git a/gcc/predict.c b/gcc/predict.c
index c12b45f..819e64c 100644
--- a/gcc/predict.c
+++ b/gcc/predict.c
@@ -2275,7 +2275,7 @@ compute_function_frequency (void)
   basic_block bb;
   struct cgraph_node *node = cgraph_get_node (current_function_decl);
   if (DECL_STATIC_CONSTRUCTOR (current_function_decl)
-      || MAIN_NAME_P (DECL_NAME (current_function_decl)))
+      || cgraph_main_function_p (node))
     node->only_called_at_startup = true;
   if (DECL_STATIC_DESTRUCTOR (current_function_decl))
     node->only_called_at_exit = true;
@@ -2291,7 +2291,7 @@ compute_function_frequency (void)
         node->frequency = NODE_FREQUENCY_HOT;
       else if (flags & ECF_NORETURN)
         node->frequency = NODE_FREQUENCY_EXECUTED_ONCE;
-      else if (MAIN_NAME_P (DECL_NAME (current_function_decl)))
+      else if (cgraph_main_function_p (node))
         node->frequency = NODE_FREQUENCY_EXECUTED_ONCE;
       else if (DECL_STATIC_CONSTRUCTOR (current_function_decl)
 	       || DECL_STATIC_DESTRUCTOR (current_function_decl))
diff --git a/gcc/tree-ssa-structalias.c b/gcc/tree-ssa-structalias.c
index b65f5aa..9cb7a16 100644
--- a/gcc/tree-ssa-structalias.c
+++ b/gcc/tree-ssa-structalias.c
@@ -6933,7 +6933,7 @@ ipa_pta_execute (void)
 
 	  /* We also need to make function return values escape.  Nothing
 	     escapes by returning from main though.  */
-	  if (!MAIN_NAME_P (DECL_NAME (node->decl)))
+	  if (!cgraph_main_function_p (node->decl))
 	    {
 	      varinfo_t fi, rvi;
 	      fi = lookup_vi_for_tree (node->decl);
diff --git a/gcc/tree.c b/gcc/tree.c
index cfea9f7..d3bbeb0 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -9477,6 +9477,8 @@ build_common_tree_nodes (bool signed_char, bool short_double)
 
     va_list_type_node = t;
   }
+
+  main_identifier_node = get_identifier ("main");
 }
 
 /* A subroutine of build_common_builtin_nodes.  Define a builtin function.  */