Re: Enable inlining into thunks

[Jan Hubicka <hubicka at ucw dot cz>]

> On 05/16/2016 12:22 AM, Jan Hubicka wrote:
> > Hi,
> > this patch teach inliner to inline into thunks. This is easy to do - all we need
> > is to produce a gimple body when we decide to do so. This fixes some ages old xfails
> > and enables some 40k inlines in Firefox. Not all those inlines are win, because
> > the codst model of thunks is wrong.  We need to model that thunk calls are really just
> > simple jumps. I will do that incrementally.
> > 
> > Bootstrapped/regtested x86_64-linux, will commit it tomorrow.
> 
> Hi Honza.
> 
> I've spotted a new ICE after I've applied all your patches (4) related
> to thunk expansion.
> 
> tc.ii:13:80: error: Thunk is not supposed to have body
>  int C::m_fn2(B &p1, int p2, int p3, int &p4) { m_fn1()->m_fn2(p1, p2, p3, p4); }

I forgot two hunks in the final patch, here is version I comitted (which also fixes the ICE you mention):

Index: cgraph.c
===================================================================
--- cgraph.c	(revision 236269)
+++ cgraph.c	(working copy)
@@ -3324,7 +3324,7 @@ cgraph_node::verify_node (void)
 	  error ("More than one edge out of thunk node");
           error_found = true;
 	}
-      if (gimple_has_body_p (decl))
+      if (gimple_has_body_p (decl) && !global.inlined_to)
         {
 	  error ("Thunk is not supposed to have body");
           error_found = true;
Index: cgraphclones.c
===================================================================
--- cgraphclones.c	(revision 236269)
+++ cgraphclones.c	(working copy)
@@ -337,8 +337,6 @@ duplicate_thunk_for_node (cgraph_node *t
 
   cgraph_edge *e = new_thunk->create_edge (node, NULL, 0,
 						  CGRAPH_FREQ_BASE);
-  e->call_stmt_cannot_inline_p = true;
-  e->inline_failed = CIF_THUNK;
   symtab->call_edge_duplication_hooks (thunk->callees, e);
   symtab->call_cgraph_duplication_hooks (thunk, new_thunk);
   return new_thunk;
Index: cif-code.def
===================================================================
--- cif-code.def	(revision 236269)
+++ cif-code.def	(working copy)
@@ -95,10 +95,6 @@ DEFCIFCODE(MISMATCHED_ARGUMENTS, CIF_FIN
 DEFCIFCODE(LTO_MISMATCHED_DECLARATIONS, CIF_FINAL_ERROR,
 	   N_("mismatched declarations during linktime optimization"))
 
-/* Caller is thunk.  */
-DEFCIFCODE(THUNK, CIF_FINAL_ERROR,                                             
-          N_("thunk call"))                                                    
-
 /* Call was originally indirect.  */
 DEFCIFCODE(ORIGINALLY_INDIRECT_CALL, CIF_FINAL_NORMAL,
 	   N_("originally indirect function call not considered for inlining"))
Index: ipa-inline-analysis.c
===================================================================
--- ipa-inline-analysis.c	(revision 236269)
+++ ipa-inline-analysis.c	(working copy)
@@ -2932,11 +2932,13 @@ compute_inline_parameters (struct cgraph
       struct inline_edge_summary *es = inline_edge_summary (node->callees);
       struct predicate t = true_predicate ();
 
-      node->callees->inline_failed = CIF_THUNK;
       node->local.can_change_signature = false;
-      es->call_stmt_size = INLINE_SIZE_SCALE;
-      es->call_stmt_time = INLINE_TIME_SCALE;
-      account_size_time (info, INLINE_SIZE_SCALE * 2, INLINE_TIME_SCALE * 2, &t);
+      es->call_stmt_size = eni_size_weights.call_cost;
+      es->call_stmt_time = eni_time_weights.call_cost;
+      account_size_time (info, INLINE_SIZE_SCALE * 2,
+			 INLINE_TIME_SCALE * 2, &t);
+      t = not_inlined_predicate ();
+      account_size_time (info, 2 * INLINE_SIZE_SCALE, 0, &t);
       inline_update_overall_summary (node);
       info->self_size = info->size;
       info->self_time = info->time;
Index: ipa-inline-transform.c
===================================================================
--- ipa-inline-transform.c	(revision 236269)
+++ ipa-inline-transform.c	(working copy)
@@ -314,12 +314,20 @@ inline_call (struct cgraph_edge *e, bool
   /* Don't even think of inlining inline clone.  */
   gcc_assert (!callee->global.inlined_to);
 
-  e->inline_failed = CIF_OK;
-  DECL_POSSIBLY_INLINED (callee->decl) = true;
-
   to = e->caller;
   if (to->global.inlined_to)
     to = to->global.inlined_to;
+  if (to->thunk.thunk_p)
+    {
+      if (in_lto_p)
+	to->get_untransformed_body ();
+      to->expand_thunk (false, true);
+      e = to->callees;
+    }
+
+
+  e->inline_failed = CIF_OK;
+  DECL_POSSIBLY_INLINED (callee->decl) = true;
 
   if (DECL_FUNCTION_PERSONALITY (callee->decl))
     DECL_FUNCTION_PERSONALITY (to->decl)
@@ -580,7 +588,7 @@ preserve_function_body_p (struct cgraph_
   gcc_assert (!node->alias && !node->thunk.thunk_p);
 
   /* Look if there is any clone around.  */
-  if (node->clones)
+  if (node->clones && !node->clones->thunk.thunk_p)
     return true;
   return false;
 }
Index: testsuite/g++.dg/ipa/ivinline-7.C
===================================================================
--- testsuite/g++.dg/ipa/ivinline-7.C	(revision 236269)
+++ testsuite/g++.dg/ipa/ivinline-7.C	(working copy)
@@ -76,4 +76,4 @@ int main (int argc, char *argv[])
 }
 
 /* { dg-final { scan-ipa-dump "Discovered a virtual call to a known target.*B::.*foo"  "inline"  } } */
-/* { dg-final { scan-ipa-dump "B::foo\[^\\n\]*inline copy in int main"  "inline"  { xfail *-*-* } } } */
+/* { dg-final { scan-ipa-dump "B::foo\[^\\n\]*inline copy in int main"  "inline"  } } */
Index: testsuite/g++.dg/ipa/ivinline-9.C
===================================================================
--- testsuite/g++.dg/ipa/ivinline-9.C	(revision 236269)
+++ testsuite/g++.dg/ipa/ivinline-9.C	(working copy)
@@ -90,4 +90,4 @@ int main (int argc, char *argv[])
 }
 
 /* { dg-final { scan-ipa-dump "Discovered a virtual call to a known target.*B::.*foo"  "inline"  } } */
-/* { dg-final { scan-ipa-dump "B::foo\[^\\n\]*inline copy in int main"  "inline"  { xfail *-*-* } } } */
+/* { dg-final { scan-ipa-dump "B::foo\[^\\n\]*inline copy in int main"  "inline"  } } */