https://gcc.gnu.org/PR88561
https://bugs.gentoo.org/676672

From 497651ff19a85affaf1273b827db6920384af77d Mon Sep 17 00:00:00 2001
From: marxin <marxin@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Thu, 27 Dec 2018 12:33:00 +0000
Subject: [PATCH] Backport r267338

2018-12-27  Martin Liska  <mliska@suse.cz>

	Backport from mainline
	2018-12-15  Jan Hubicka  <hubicka@ucw.cz>

	PR ipa/88561
	* ipa-polymorphic-call.c
	(ipa_polymorphic_call_context::ipa_polymorphic_call_context): Handle
	arguments of thunks correctly.
	(ipa_polymorphic_call_context::get_dynamic_context): Be ready for
	NULL instance pinter.
	* lto-cgraph.c (lto_output_node): Always stream thunk info.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-8-branch@267433 138bc75d-0d04-0410-961f-82ee72b054a4
---
 gcc/ipa-polymorphic-call.c              |  32 +++++-
 gcc/lto-cgraph.c                        |   8 +-

--- a/gcc/ipa-polymorphic-call.c
+++ b/gcc/ipa-polymorphic-call.c
@@ -995,9 +995,22 @@ ipa_polymorphic_call_context::ipa_polymorphic_call_context (tree fndecl,
 	{
 	  outer_type
 	     = TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (base_pointer)));
+	  cgraph_node *node = cgraph_node::get (current_function_decl);
 	  gcc_assert (TREE_CODE (outer_type) == RECORD_TYPE
 		      || TREE_CODE (outer_type) == UNION_TYPE);
 
+	  /* Handle the case we inlined into a thunk.  In this case
+	     thunk has THIS pointer of type bar, but it really receives
+	     address to its base type foo which sits in bar at
+	     0-thunk.fixed_offset.  It starts with code that adds
+	     think.fixed_offset to the pointer to compensate for this.
+
+	     Because we walked all the way to the begining of thunk, we now
+	     see pointer &bar-thunk.fixed_offset and need to compensate
+	     for it.  */
+	  if (node->thunk.fixed_offset)
+	    offset -= node->thunk.fixed_offset * BITS_PER_UNIT;
+
 	  /* Dynamic casting has possibly upcasted the type
 	     in the hiearchy.  In this case outer type is less
 	     informative than inner type and we should forget
@@ -1005,7 +1018,11 @@ ipa_polymorphic_call_context::ipa_polymorphic_call_context (tree fndecl,
 	  if ((otr_type
 	       && !contains_type_p (outer_type, offset,
 				    otr_type))
-	      || !contains_polymorphic_type_p (outer_type))
+	      || !contains_polymorphic_type_p (outer_type)
+	      /* If we compile thunk with virtual offset, the THIS pointer
+		 is adjusted by unknown value.  We can't thus use outer info
+		 at all.  */
+	      || node->thunk.virtual_offset_p)
 	    {
 	      outer_type = NULL;
 	      if (instance)
@@ -1030,7 +1047,15 @@ ipa_polymorphic_call_context::ipa_polymorphic_call_context (tree fndecl,
 	      maybe_in_construction = false;
 	    }
 	  if (instance)
-	    *instance = base_pointer;
+	    {
+	      /* If method is expanded thunk, we need to apply thunk offset
+		 to instance pointer.  */
+	      if (node->thunk.virtual_offset_p
+		  || node->thunk.fixed_offset)
+		*instance = NULL;
+	      else
+	        *instance = base_pointer;
+	    }
 	  return;
 	}
       /* Non-PODs passed by value are really passed by invisible
@@ -1547,6 +1572,9 @@ ipa_polymorphic_call_context::get_dynamic_type (tree instance,
   HOST_WIDE_INT instance_offset = offset;
   tree instance_outer_type = outer_type;
 
+  if (!instance)
+    return false;
+
   if (otr_type)
     otr_type = TYPE_MAIN_VARIANT (otr_type);
 
--- a/gcc/lto-cgraph.c
+++ b/gcc/lto-cgraph.c
@@ -546,7 +546,11 @@ lto_output_node (struct lto_simple_output_block *ob, struct cgraph_node *node,
   streamer_write_bitpack (&bp);
   streamer_write_data_stream (ob->main_stream, section, strlen (section) + 1);
 
-  if (node->thunk.thunk_p)
+  /* Stream thunk info always because we use it in
+     ipa_polymorphic_call_context::ipa_polymorphic_call_context
+     to properly interpret THIS pointers for thunks that has been converted
+     to Gimple.  */
+  if (node->definition)
     {
       streamer_write_uhwi_stream
 	 (ob->main_stream,
@@ -1317,7 +1321,7 @@ input_node (struct lto_file_decl_data *file_data,
   if (section)
     node->set_section_for_node (section);
 
-  if (node->thunk.thunk_p)
+  if (node->definition)
     {
       int type = streamer_read_uhwi (ib);
       HOST_WIDE_INT fixed_offset = streamer_read_uhwi (ib);