[PATCH, PR 43905] Make IPA-SRA clone functions it modifies

[Martin Jambor <mjambor at suse dot cz>]

Hi,

the patch below is basically a different fix to PR 43141 which fixes
the still-opened PR 43905 and a number of issues that that first
attempt caused (e.g. wrong sharing of parameter chain list and some
debug info problems).  After trying quite hard to move the body of a
function from the old declaration to a new one and all necessary
fixing up so that nothing breaks, I gave up and resorted to simple
cloning.

Fortunately the pass management works in a way that setting the cfun
and current_function_decl to the new function is enough to make the
subsequent passes work on the correct function.  It is a bit of a
hack, but I can't think of any substantial improvement.

The patch also does not deal with same_body aliases.  I hope it is not
necessary.

And that is what the patch does.  I have bootstrapped and tested it on
x86_64-linux with no problems.  Is it OK for trunk and for 4.5 after a
while?

Thanks,

Martin


2010-06-10  Martin Jambor  <mjambor@suse.cz>

	PR tree-optimization/43905
	* tree-sra.c (create_abstract_origin): Removed.
	(modify_function): Version the call graph node instead of creating
	abstract origins and dealing with same_body aliases.

	* testsuite/g++.dg/torture/pr43905.C

Index: mine/gcc/tree-sra.c
===================================================================
--- mine.orig/gcc/tree-sra.c
+++ mine/gcc/tree-sra.c
@@ -4224,43 +4224,38 @@ convert_callers (struct cgraph_node *nod
   return;
 }
 
-/* Create an abstract origin declaration for OLD_DECL and make it an abstract
-   origin of the provided decl so that there are preserved parameters for debug
-   information.  */
-
-static void
-create_abstract_origin (tree old_decl)
-{
-  if (!DECL_ABSTRACT_ORIGIN (old_decl))
-    {
-      tree new_decl = copy_node (old_decl);
-
-      DECL_ABSTRACT (new_decl) = 1;
-      SET_DECL_ASSEMBLER_NAME (new_decl, NULL_TREE);
-      SET_DECL_RTL (new_decl, NULL);
-      DECL_STRUCT_FUNCTION (new_decl) = NULL;
-      DECL_ARTIFICIAL (old_decl) = 1;
-      DECL_ABSTRACT_ORIGIN (old_decl) = new_decl;
-    }
-}
-
 /* Perform all the modification required in IPA-SRA for NODE to have parameters
    as given in ADJUSTMENTS.  */
 
 static void
 modify_function (struct cgraph_node *node, ipa_parm_adjustment_vec adjustments)
 {
-  struct cgraph_node *alias;
-  for (alias = node->same_body; alias; alias = alias->next)
-    ipa_modify_formal_parameters (alias->decl, adjustments, "ISRA");
-  /* current_function_decl must be handled last, after same_body aliases,
-     as following functions will use what it computed.  */
-  create_abstract_origin (current_function_decl);
+  struct cgraph_node *new_node;
+  struct cgraph_edge *cs;
+  VEC (cgraph_edge_p, heap) * redirect_callers;
+  int node_callers;
+
+  node_callers = 0;
+  for (cs = node->callers; cs != NULL; cs = cs->next_caller)
+    node_callers++;
+  redirect_callers = VEC_alloc (cgraph_edge_p, heap, node_callers);
+  for (cs = node->callers; cs != NULL; cs = cs->next_caller)
+    VEC_quick_push (cgraph_edge_p, redirect_callers, cs);
+
+  rebuild_cgraph_edges ();
+  pop_cfun ();
+  current_function_decl = NULL_TREE;
+
+  new_node = cgraph_function_versioning (node, redirect_callers, NULL, NULL,
+					 NULL, NULL, "isra");
+  current_function_decl = new_node->decl;
+  push_cfun (DECL_STRUCT_FUNCTION (new_node->decl));
+
   ipa_modify_formal_parameters (current_function_decl, adjustments, "ISRA");
   ipa_sra_modify_function_body (adjustments);
   sra_ipa_reset_debug_stmts (adjustments);
-  convert_callers (node, adjustments);
-  cgraph_make_node_local (node);
+  convert_callers (new_node, adjustments);
+  cgraph_make_node_local (new_node);
   return;
 }
 
Index: mine/gcc/testsuite/g++.dg/torture/pr43905.C
===================================================================
--- /dev/null
+++ mine/gcc/testsuite/g++.dg/torture/pr43905.C
@@ -0,0 +1,13 @@
+extern void sf ( __const char *);
+struct Matrix{
+  int operator[](int n){
+    sf ( __PRETTY_FUNCTION__);
+  }
+  int operator[](int n)const{
+    sf ( __PRETTY_FUNCTION__);
+  }
+};
+void calcmy(Matrix const &b, Matrix &c, int k){
+  b[k];
+  c[k];
+}