[PATCH] Do not run IPA transform phases multiple times

[Martin Jambor <mjambor at suse dot cz>]

Hi,

I have noticed that we often run IPA-transformation phases multiple
times.  The reason is that when a virtual clone is created, it starts
with an empty ipa_transforms_to_apply vector and all subsequent IPA
passes that see it are pushed onto it.  The original node gets these
pushed on their ipa_transforms_to_apply too.  Later on, when a clone
receives its body, in tree_function_versioning, the contents of
original node's ipa_transforms_to_apply is added to clone's
ipa_transforms_to_apply (in a slightly convoluted way).  I do not
understand how this was supposed to work but obviously we can and do
end up with multiple copies of a few passes in ipa_transforms_to_apply
of the clone.

I believe the correct thing to do is to copy the vector when the
virtual clone is created and remove the part in
tree_function_versioning that does the copying.  I have verified that
we no longer call transformation of IPA-CP multiple times when we
previously did and added asserts to check that no other caller of
tree_function_versioning expects to have the vector copied.

Bootstrapped and tested on x86_64-linux, OK for trunk?

Thanks,

Martin


2014-04-10  Martin Jambor  <mjambor@suse.cz>

	* cgraphclones.c (cgraph_create_virtual_clone): Duplicate
	ipa_transforms_to_apply.
	(cgraph_function_versioning): Assert that old_node has empty
	ipa_transforms_to_apply.
	* trans-mem.c (ipa_tm_create_version): Likewise.
	* tree-inline.c (tree_function_versioning): Do not duplicate
	ipa_transforms_to_apply.

Index: src/gcc/cgraphclones.c
===================================================================
--- src.orig/gcc/cgraphclones.c
+++ src/gcc/cgraphclones.c
@@ -600,6 +600,9 @@ cgraph_create_virtual_clone (struct cgra
     }
   else
     new_node->clone.combined_args_to_skip = args_to_skip;
+  if (old_node->ipa_transforms_to_apply.exists ())
+    new_node->ipa_transforms_to_apply
+      = old_node->ipa_transforms_to_apply.copy ();
 
   cgraph_call_node_duplication_hooks (old_node, new_node);
 
@@ -971,6 +974,7 @@ cgraph_function_versioning (struct cgrap
     cgraph_copy_node_for_versioning (old_version_node, new_decl,
 				     redirect_callers, bbs_to_copy);
 
+  gcc_assert (!old_version_node->ipa_transforms_to_apply.exists ());
   /* Copy the OLD_VERSION_NODE function tree to the new version.  */
   tree_function_versioning (old_decl, new_decl, tree_map, false, args_to_skip,
 			    skip_return, bbs_to_copy, new_entry_block);
Index: src/gcc/trans-mem.c
===================================================================
--- src.orig/gcc/trans-mem.c
+++ src/gcc/trans-mem.c
@@ -4914,6 +4914,7 @@ ipa_tm_create_version (struct cgraph_nod
   if (DECL_ONE_ONLY (new_decl))
     DECL_COMDAT_GROUP (new_decl) = tm_mangle (DECL_COMDAT_GROUP (old_decl));
 
+  gcc_assert (!old_node->ipa_transforms_to_apply.exists ());
   new_node = cgraph_copy_node_for_versioning (old_node, new_decl, vNULL, NULL);
   new_node->local.local = false;
   new_node->externally_visible = old_node->externally_visible;
Index: src/gcc/tree-inline.c
===================================================================
--- src.orig/gcc/tree-inline.c
+++ src/gcc/tree-inline.c
@@ -5323,18 +5323,6 @@ tree_function_versioning (tree old_decl,
   id.dst_node = new_version_node;
   id.src_cfun = DECL_STRUCT_FUNCTION (old_decl);
   id.blocks_to_copy = blocks_to_copy;
-  if (id.src_node->ipa_transforms_to_apply.exists ())
-    {
-      vec<ipa_opt_pass> old_transforms_to_apply
-	    = id.dst_node->ipa_transforms_to_apply;
-      unsigned int i;
-
-      id.dst_node->ipa_transforms_to_apply
-	    = id.src_node->ipa_transforms_to_apply.copy ();
-      for (i = 0; i < old_transforms_to_apply.length (); i++)
-        id.dst_node->ipa_transforms_to_apply.safe_push (old_transforms_to_apply[i]);
-      old_transforms_to_apply.release ();
-    }
 
   id.copy_decl = copy_decl_no_change;
   id.transform_call_graph_edges