extend.texi (Labels as Values): Document need for noclone.

2009-07-25  Martin Jambor  <mjambor@suse.cz>

	* doc/extend.texi (Labels as Values): Document need for noclone.
	(Function Attributes): Document noclone attribute.
	* c-common.c (c_common_attribute_table): New element for noclone.
	(handle_noclone_attribute): New function. Forward-declare.
	* tree-inline.c (tree_versionable_function_p): Check for noclone
	attribute.

	* testsuite/gcc.c-torture/execute/pr17377.c: Add noclone attribute to
	function y.
	* testsuite/gcc.dg/ipa/noclone-1.c: New test.

From-SVN: r150086

gcc/ChangeLog

+2009-07-25  Martin Jambor  <mjambor@suse.cz>
+
+	* c-common.c (c_common_attribute_table): New element for noclone.
+	(handle_noclone_attribute): New function. Forward-declare.
+	* tree-inline.c (tree_versionable_function_p): Check for noclone
+	attribute.
+	* doc/extend.texi (Labels as Values): Document need for noclone.
+	(Function Attributes): Document noclone attribute.
+
 2009-07-25  Jakub Jelinek  <jakub@redhat.com>
 
 	PR rtl-optimization/34999

gcc/c-common.c

@@ -482,6 +482,7 @@ static tree handle_noreturn_attribute (tree *, tree, tree, int, bool *);
 static tree handle_hot_attribute (tree *, tree, tree, int, bool *);
 static tree handle_cold_attribute (tree *, tree, tree, int, bool *);
 static tree handle_noinline_attribute (tree *, tree, tree, int, bool *);
+static tree handle_noclone_attribute (tree *, tree, tree, int, bool *);
 static tree handle_always_inline_attribute (tree *, tree, tree, int,
 					    bool *);
 static tree handle_gnu_inline_attribute (tree *, tree, tree, int, bool *);
@@ -733,6 +734,8 @@ const struct attribute_spec c_common_attribute_table[] =
 			      handle_noreturn_attribute },
   { "noinline",               0, 0, true,  false, false,
 			      handle_noinline_attribute },
+  { "noclone",                0, 0, true,  false, false,
+			      handle_noclone_attribute },
   { "always_inline",          0, 0, true,  false, false,
 			      handle_always_inline_attribute },
   { "gnu_inline",             0, 0, true,  false, false,
@@ -5913,6 +5916,23 @@ handle_noinline_attribute (tree *node, tree name,
   return NULL_TREE;
 }
 
+/* Handle a "noclone" attribute; arguments as in
+   struct attribute_spec.handler.  */
+
+static tree
+handle_noclone_attribute (tree *node, tree name,
+			  tree ARG_UNUSED (args),
+			  int ARG_UNUSED (flags), bool *no_add_attrs)
+{
+  if (TREE_CODE (*node) != FUNCTION_DECL)
+    {
+      warning (OPT_Wattributes, "%qE attribute ignored", name);
+      *no_add_attrs = true;
+    }
+
+  return NULL_TREE;
+}
+
 /* Handle a "always_inline" attribute; arguments as in
    struct attribute_spec.handler.  */
 

gcc/doc/extend.texi

@@ -372,11 +372,12 @@ This is more friendly to code living in shared libraries, as it reduces
 the number of dynamic relocations that are needed, and by consequence,
 allows the data to be read-only.
 
-The @code{&&foo} expressions for the same label might have different values
-if the containing function is inlined or cloned.  If a program relies on
-them being always the same, @code{__attribute__((__noinline__))} should
-be used to prevent inlining.  If @code{&&foo} is used
-in a static variable initializer, inlining is forbidden.
+The @code{&&foo} expressions for the same label might have different
+values if the containing function is inlined or cloned.  If a program
+relies on them being always the same,
+@code{__attribute__((__noinline__,__noclone__))} should be used to
+prevent inlining and cloning.  If @code{&&foo} is used in a static
+variable initializer, inlining and cloning is forbidden.
 
 @node Nested Functions
 @section Nested Functions
@@ -1881,19 +1882,18 @@ attributes when making a declaration.  This keyword is followed by an
 attribute specification inside double parentheses.  The following
 attributes are currently defined for functions on all targets:
 @code{aligned}, @code{alloc_size}, @code{noreturn},
-@code{returns_twice}, @code{noinline}, @code{always_inline},
-@code{flatten}, @code{pure}, @code{const}, @code{nothrow},
-@code{sentinel}, @code{format}, @code{format_arg},
+@code{returns_twice}, @code{noinline}, @code{noclone},
+@code{always_inline}, @code{flatten}, @code{pure}, @code{const},
+@code{nothrow}, @code{sentinel}, @code{format}, @code{format_arg},
 @code{no_instrument_function}, @code{section}, @code{constructor},
 @code{destructor}, @code{used}, @code{unused}, @code{deprecated},
 @code{weak}, @code{malloc}, @code{alias}, @code{warn_unused_result},
 @code{nonnull}, @code{gnu_inline}, @code{externally_visible},
-@code{hot}, @code{cold}, @code{artificial}, @code{error}
-and @code{warning}.
-Several other attributes are defined for functions on particular
-target systems.  Other attributes, including @code{section} are
-supported for variables declarations (@pxref{Variable Attributes}) and
-for types (@pxref{Type Attributes}).
+@code{hot}, @code{cold}, @code{artificial}, @code{error} and
+@code{warning}.  Several other attributes are defined for functions on
+particular target systems.  Other attributes, including @code{section}
+are supported for variables declarations (@pxref{Variable Attributes})
+and for types (@pxref{Type Attributes}).
 
 You may also specify attributes with @samp{__} preceding and following
 each keyword.  This allows you to use them in header files without
@@ -2718,6 +2718,13 @@ asm ("");
 (@pxref{Extended Asm}) in the called function, to serve as a special
 side-effect.
 
+@item noclone
+@cindex @code{noclone} function attribute
+This function attribute prevents a function from being considered for
+cloning - a mechanism which produces specialized copies of functions
+and which is (currently) performed by interprocedural constant
+propagation.
+
 @item nonnull (@var{arg-index}, @dots{})
 @cindex @code{nonnull} function attribute
 The @code{nonnull} attribute specifies that some function parameters should

gcc/testsuite/ChangeLog

+2009-07-25  Martin Jambor  <mjambor@suse.cz>
+
+	* gcc.c-torture/execute/pr17377.c: Add noclone attribute to function y.
+	* gcc.dg/ipa/noclone-1.c: New test.
+
 2009-07-25  Uros Bizjak  <ubizjak@gmail.com>
 
 	* lib/target-supports.exp (check_effective_target_static): New

gcc/testsuite/gcc.c-torture/execute/pr17377.c

@@ -26,7 +26,7 @@ f (int i)
 
 int x;
 
-void *y (int i) __attribute__ ((__noinline__));
+void *y (int i) __attribute__ ((__noinline__,__noclone__));
 void *
 y (int i)
 {

gcc/testsuite/gcc.dg/ipa/noclone-1.c

+/* { dg-do compile } */
+/* { dg-options "-O3 -fipa-cp -fipa-cp-clone -fdump-ipa-cp -fno-early-inlining"  } */
+
+int global_1, global_2;
+
+__attribute__((__noclone__)) int g (int b, int c)
+ {
+  global_1 = b;
+  global_2 = c;
+}
+
+__attribute__((__noclone__)) int f (int a)
+{
+  /* Second parameter of g gets different values.  */
+  if (a > 0)
+    g (a, 3);
+  else
+    g (a, 5);
+}
+
+int main ()
+{
+  f (7);
+  return 0;
+}
+
+
+/* { dg-final { scan-ipa-dump-times "versioned function" 0 "cp"  } } */
+/* { dg-final { cleanup-ipa-dump "cp" } } */

gcc/tree-inline.c

@@ -4349,7 +4349,8 @@ copy_static_chain (tree static_chain, copy_body_data * id)
 bool
 tree_versionable_function_p (tree fndecl)
 {
-  return copy_forbidden (DECL_STRUCT_FUNCTION (fndecl), fndecl) == NULL;
+  return (!lookup_attribute ("noclone", DECL_ATTRIBUTES (fndecl))
+	  && copy_forbidden (DECL_STRUCT_FUNCTION (fndecl), fndecl) == NULL);
 }
 
 /* Delete all unreachable basic blocks and update callgraph.