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Re: [PATCH, PR 61160] Artificial thunks need combined_args_to_skip


On Sat, May 31, 2014 at 01:08:31AM +0200, Martin Jambor wrote:
> Hi,
> 
> the second issue in PR 61160 is that because artificial thunks
> (produced by duplicate_thunk_for_node) do not have
> combined_args_to_skip, calls to them do not get actual arguments
> removed, while the actual functions do loose their formal parameters,
> leading to mismatches.
> 
> Currently, the combined_args_to_skip is computed in of
> cgraph_create_virtual_clone only after all the edge redirection and
> thunk duplication is done so it had to be moved to a spot before
> that.  Since we already pass args_to_skip to cgraph_clone_node, I
> moved the computation there (otherwise it would have to duplicate the
> old value and also pass the new one to the redirection routine).
> 
> I have also noticed that the code producing combined_args_to_skip from
> an old value and new args_to_skip cannot work in LTO because we do not
> have DECL_ARGUMENTS available at WPA in LTO.  The wrong code is
> however never executed and so I replaced it with a simple bitmap_ior.
> This changes the semantics of args_to_skip for any user of
> cgraph_create_virtual_clone that would like to remove some parameters
> from something which is already a clone.  However, currently there are
> no such users and the new semantics is saner because WPA code will be
> happier using the old indices rather than remapping everything the
> whole time.
> 
> I am still in the process of bootstrapping and testing this patch on
> trunk, I will test it on the 4.9 branch too.  OK if it passes
> everywhere?
> 

The patch has been approved by Honza on IRC.  Since then, a conflict
has occured on the trunk so I committed this variant after re-testing.

Thanks,

Martin


2014-06-27  Martin Jambor  <mjambor@suse.cz>

	PR ipa/61160
	* cgraphclones.c (duplicate_thunk_for_node): Removed parameter
	args_to_skip, use those from node instead.  Copy args_to_skip and
	combined_args_to_skip from node to the new thunk.
	(redirect_edge_duplicating_thunks): Removed parameter args_to_skip.
	(cgraph_create_virtual_clone): Moved computation of
	combined_args_to_skip...
	(cgraph_clone_node): ...here, simplify it to bitmap_ior..

testsuite/
	* g++.dg/ipa/pr61160-2.C: New test.
	* g++.dg/ipa/pr61160-3.C: Likewise.

diff --git a/gcc/cgraphclones.c b/gcc/cgraphclones.c
index d57cd9f..2e7dc90 100644
--- a/gcc/cgraphclones.c
+++ b/gcc/cgraphclones.c
@@ -301,14 +301,13 @@ set_new_clone_decl_and_node_flags (cgraph_node *new_node)
    thunk is this_adjusting but we are removing this parameter.  */
 
 static cgraph_node *
-duplicate_thunk_for_node (cgraph_node *thunk, cgraph_node *node,
-			  bitmap args_to_skip)
+duplicate_thunk_for_node (cgraph_node *thunk, cgraph_node *node)
 {
   cgraph_node *new_thunk, *thunk_of;
   thunk_of = cgraph_function_or_thunk_node (thunk->callees->callee);
 
   if (thunk_of->thunk.thunk_p)
-    node = duplicate_thunk_for_node (thunk_of, node, args_to_skip);
+    node = duplicate_thunk_for_node (thunk_of, node);
 
   struct cgraph_edge *cs;
   for (cs = node->callers; cs; cs = cs->next_caller)
@@ -320,17 +319,18 @@ duplicate_thunk_for_node (cgraph_node *thunk, cgraph_node *node,
       return cs->caller;
 
   tree new_decl;
-  if (!args_to_skip)
+  if (!node->clone.args_to_skip)
     new_decl = copy_node (thunk->decl);
   else
     {
       /* We do not need to duplicate this_adjusting thunks if we have removed
 	 this.  */
       if (thunk->thunk.this_adjusting
-	  && bitmap_bit_p (args_to_skip, 0))
+	  && bitmap_bit_p (node->clone.args_to_skip, 0))
 	return node;
 
-      new_decl = build_function_decl_skip_args (thunk->decl, args_to_skip,
+      new_decl = build_function_decl_skip_args (thunk->decl,
+						node->clone.args_to_skip,
 						false);
     }
   gcc_checking_assert (!DECL_STRUCT_FUNCTION (new_decl));
@@ -347,6 +347,8 @@ duplicate_thunk_for_node (cgraph_node *thunk, cgraph_node *node,
   new_thunk->thunk = thunk->thunk;
   new_thunk->unique_name = in_lto_p;
   new_thunk->former_clone_of = thunk->decl;
+  new_thunk->clone.args_to_skip = node->clone.args_to_skip;
+  new_thunk->clone.combined_args_to_skip = node->clone.combined_args_to_skip;
 
   struct cgraph_edge *e = cgraph_create_edge (new_thunk, node, NULL, 0,
 					      CGRAPH_FREQ_BASE);
@@ -363,12 +365,11 @@ duplicate_thunk_for_node (cgraph_node *thunk, cgraph_node *node,
    chain.  */
 
 void
-redirect_edge_duplicating_thunks (struct cgraph_edge *e, struct cgraph_node *n,
-				  bitmap args_to_skip)
+redirect_edge_duplicating_thunks (struct cgraph_edge *e, struct cgraph_node *n)
 {
   cgraph_node *orig_to = cgraph_function_or_thunk_node (e->callee);
   if (orig_to->thunk.thunk_p)
-    n = duplicate_thunk_for_node (orig_to, n, args_to_skip);
+    n = duplicate_thunk_for_node (orig_to, n);
 
   cgraph_redirect_edge_callee (e, n);
 }
@@ -421,9 +422,21 @@ cgraph_clone_node (struct cgraph_node *n, tree decl, gcov_type count, int freq,
   new_node->rtl = n->rtl;
   new_node->count = count;
   new_node->frequency = n->frequency;
-  new_node->clone = n->clone;
-  new_node->clone.tree_map = NULL;
   new_node->tp_first_run = n->tp_first_run;
+
+  new_node->clone.tree_map = NULL;
+  new_node->clone.args_to_skip = args_to_skip;
+  if (!args_to_skip)
+    new_node->clone.combined_args_to_skip = n->clone.combined_args_to_skip;
+  else if (n->clone.combined_args_to_skip)
+    {
+      new_node->clone.combined_args_to_skip = BITMAP_GGC_ALLOC ();
+      bitmap_ior (new_node->clone.combined_args_to_skip,
+		  n->clone.combined_args_to_skip, args_to_skip);
+    }
+  else
+    new_node->clone.combined_args_to_skip = args_to_skip;
+
   if (n->count)
     {
       if (new_node->count > n->count)
@@ -448,10 +461,9 @@ cgraph_clone_node (struct cgraph_node *n, tree decl, gcov_type count, int freq,
       if (!e->callee
 	  || DECL_BUILT_IN_CLASS (e->callee->decl) != BUILT_IN_NORMAL
 	  || DECL_FUNCTION_CODE (e->callee->decl) != BUILT_IN_UNREACHABLE)
-        redirect_edge_duplicating_thunks (e, new_node, args_to_skip);
+        redirect_edge_duplicating_thunks (e, new_node);
     }
 
-
   for (e = n->callees;e; e=e->next_callee)
     cgraph_clone_edge (e, new_node, e->call_stmt, e->lto_stmt_uid,
 		       count_scale, freq, update_original);
@@ -558,7 +570,6 @@ cgraph_create_virtual_clone (struct cgraph_node *old_node,
      ABI support for this.  */
   set_new_clone_decl_and_node_flags (new_node);
   new_node->clone.tree_map = tree_map;
-  new_node->clone.args_to_skip = args_to_skip;
 
   /* Clones of global symbols or symbols with unique names are unique.  */
   if ((TREE_PUBLIC (old_decl)
@@ -569,32 +580,7 @@ cgraph_create_virtual_clone (struct cgraph_node *old_node,
     new_node->unique_name = true;
   FOR_EACH_VEC_SAFE_ELT (tree_map, i, map)
     new_node->maybe_add_reference (map->new_tree, IPA_REF_ADDR, NULL);
-  if (!args_to_skip)
-    new_node->clone.combined_args_to_skip = old_node->clone.combined_args_to_skip;
-  else if (old_node->clone.combined_args_to_skip)
-    {
-      int newi = 0, oldi = 0;
-      tree arg;
-      bitmap new_args_to_skip = BITMAP_GGC_ALLOC ();
-      struct cgraph_node *orig_node;
-      for (orig_node = old_node; orig_node->clone_of; orig_node = orig_node->clone_of)
-        ;
-      for (arg = DECL_ARGUMENTS (orig_node->decl);
-	   arg; arg = DECL_CHAIN (arg), oldi++)
-	{
-	  if (bitmap_bit_p (old_node->clone.combined_args_to_skip, oldi))
-	    {
-	      bitmap_set_bit (new_args_to_skip, oldi);
-	      continue;
-	    }
-	  if (bitmap_bit_p (args_to_skip, newi))
-	    bitmap_set_bit (new_args_to_skip, oldi);
-	  newi++;
-	}
-      new_node->clone.combined_args_to_skip = new_args_to_skip;
-    }
-  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 ();
diff --git a/gcc/testsuite/g++.dg/ipa/pr61160-2.C b/gcc/testsuite/g++.dg/ipa/pr61160-2.C
new file mode 100644
index 0000000..1011bd1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ipa/pr61160-2.C
@@ -0,0 +1,43 @@
+/* { dg-do run } */
+/* { dg-options "-O3 --param ipa-cp-eval-threshold=1"  } */
+
+extern "C" void abort (void);
+
+struct CBase {
+  virtual void BaseFunc () {}
+};
+
+struct MMixin {
+  virtual void * MixinFunc (int, void *) = 0;
+};
+
+struct CExample: CBase, public MMixin
+{
+  int stuff, magic, more_stuff;
+
+  CExample ()
+  {
+    stuff = 0;
+    magic = 0xbeef;
+    more_stuff = 0;
+  }
+  void *MixinFunc (int arg, void *arg2)
+  {
+    if (arg != 1 || arg2)
+      return 0;
+    if (magic != 0xbeef)
+      abort();
+    return this;
+  }
+};
+
+void *test (MMixin & anExample)
+{
+  return anExample.MixinFunc (1, 0);
+}
+
+int main ()
+{
+  CExample c;
+  return (test (c) != &c);
+}
diff --git a/gcc/testsuite/g++.dg/ipa/pr61160-3.C b/gcc/testsuite/g++.dg/ipa/pr61160-3.C
new file mode 100644
index 0000000..8184ec2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ipa/pr61160-3.C
@@ -0,0 +1,37 @@
+/* { dg-do run } */
+/* { dg-options "-O3"  } */
+
+struct A {
+  void *p;
+  A (void *q) : p (q) {}
+  A (const A &) : p () {}
+};
+
+struct CBase {
+  virtual void BaseFunc () {}
+};
+
+struct MMixin {
+  virtual A MixinFunc (int, A) = 0;
+};
+
+struct CExample: CBase, public MMixin
+{
+  A MixinFunc (int arg, A arg2)
+  {
+    if (arg != 1 || arg2.p)
+      return 0;
+    return this;
+  }
+};
+
+void *test (MMixin & anExample)
+{
+  return anExample.MixinFunc (1, (0)).p;
+}
+
+int main ()
+{
+  CExample c;
+  return (test (c) != &c);
+}


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