decl2.c (generate_ctor_or_dtor_function): Avoid expanding a global static constructor...

	* decl2.c (generate_ctor_or_dtor_function): Avoid expanding a
	global static constructor/destructor if it will be empty, i.e.
	either doesn't call any ctors/dtors or only calls pure or const
	ctors/dtors.

From-SVN: r67800

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index a4b9bef89abcf898f52ae89fe539fb3f11d4ab81..03c02c4ef599816ac80efa8ee378bf2912dc7410 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,10 @@
+2003-06-11  Roger Sayle  <roger@eyesopen.com>
+
+       * decl2.c (generate_ctor_or_dtor_function): Avoid expanding a 
+       global static constructor/destructor if it will be empty, i.e.
+       either doesn't call any ctors/dtors or only calls pure or const
+       ctors/dtors.
+
 2003-06-11  Mark Mitchell  <mark@codesourcery.com>
 
        * mangle.c (tm_p.h): Include it.

diff --git a/gcc/cp/decl2.c b/gcc/cp/decl2.c
index 08a2d663b2a3b423c942037b38b548c01e0df056..1413f3944b9b89d017fddd9c0feb2f0b5b1ca0c3 100644 (file)
--- a/gcc/cp/decl2.c
+++ b/gcc/cp/decl2.c
@@ -2467,6 +2467,7 @@ generate_ctor_or_dtor_function (bool constructor_p, int priority,
 {
   char function_key;
   tree arguments;
+  tree fndecl;
   tree body;
   size_t i;
 
@@ -2475,25 +2476,31 @@ generate_ctor_or_dtor_function (bool constructor_p, int priority,
   
   /* We use `I' to indicate initialization and `D' to indicate
      destruction.  */
-  if (constructor_p)
-    function_key = 'I';
-  else
-    function_key = 'D';
+  function_key = constructor_p ? 'I' : 'D';
 
-  /* Begin the function.  */
-  body = start_objects (function_key, priority);
+  /* We emit the function lazily, to avoid generating empty
+     global constructors and destructors.  */
+  body = NULL_TREE;
 
   /* Call the static storage duration function with appropriate
      arguments.  */
   if (ssdf_decls)
     for (i = 0; i < ssdf_decls->elements_used; ++i) 
       {
-       arguments = tree_cons (NULL_TREE, build_int_2 (priority, 0), 
-                              NULL_TREE);
-       arguments = tree_cons (NULL_TREE, build_int_2 (constructor_p, 0),
-                              arguments);
-       finish_expr_stmt (build_function_call (VARRAY_TREE (ssdf_decls, i),
-                                              arguments));
+       fndecl = VARRAY_TREE (ssdf_decls, i);
+
+       /* Calls to pure or const functions will expand to nothing.  */
+       if (! (flags_from_decl_or_type (fndecl) & (ECF_CONST | ECF_PURE)))
+         {
+           if (! body)
+             body = start_objects (function_key, priority);
+
+           arguments = tree_cons (NULL_TREE, build_int_2 (priority, 0), 
+                                  NULL_TREE);
+           arguments = tree_cons (NULL_TREE, build_int_2 (constructor_p, 0),
+                                  arguments);
+           finish_expr_stmt (build_function_call (fndecl, arguments));
+         }
       }
 
   /* If we're generating code for the DEFAULT_INIT_PRIORITY, throw in
@@ -2506,11 +2513,22 @@ generate_ctor_or_dtor_function (bool constructor_p, int priority,
       for (fns = constructor_p ? static_ctors : static_dtors; 
           fns;
           fns = TREE_CHAIN (fns))
-       finish_expr_stmt (build_function_call (TREE_VALUE (fns), NULL_TREE));
+       {
+         fndecl = TREE_VALUE (fns);
+
+         /* Calls to pure/const functions will expand to nothing.  */
+         if (! (flags_from_decl_or_type (fndecl) & (ECF_CONST | ECF_PURE)))
+           {
+             if (! body)
+               body = start_objects (function_key, priority);
+             finish_expr_stmt (build_function_call (fndecl, NULL_TREE));
+           }
+       }
     }
 
   /* Close out the function.  */
-  finish_objects (function_key, priority, body);
+  if (body)
+    finish_objects (function_key, priority, body);
 }
 
 /* Generate constructor and destructor functions for the priority