--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/lto-wpa-fixup.c	Fri Feb 12 23:39:51 2010 +0900
@@ -0,0 +1,282 @@
+/* Write and read any fix-up information generated by the WPA mode.
+
+   Copyright 2009 Free Software Foundation, Inc.
+   Contributed by Doug Kwan <dougkwan@google.com>
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "toplev.h"
+#include "tree.h"
+#include "expr.h"
+#include "flags.h"
+#include "cgraph.h"
+#include "function.h"
+#include "diagnostic.h"
+#include "vec.h"
+#include "bitmap.h"
+#include "timevar.h"
+#include "tree-flow.h"
+#include "tree-pass.h"
+#include "lto-streamer.h"
+
+/* LTO fix-up.
+
+   In WPA mode, LTO cannot access function bodies.  Some modifications in
+   IR require additional updates in function bodies,  which are not possible
+   in WPA mode.  So we write out information about these modifications for
+   LTRANS to fix up the function bodies accordingly.  */
+
+/* The vectors records function DECLs having multiple copies with different
+   exception throwing attributes.  We do not mark a DECL if all copies of it
+   have the same exception throwing attribute. */
+static bitmap lto_nothrow_fndecls;
+
+/* We need to fix up GIMPLE bodies due to changes in exception setting.
+   Consider this example:
+
+   a.h:
+   class a {
+   public:
+     a();
+     ~a();
+   };
+
+   main.cc:
+   #include "a.h"
+
+   int
+   main (int argc, char **argv)
+   {
+     a x;
+     return 0;
+   }
+
+   a.cc:
+   #include "a.h"
+   a::a() {}
+   a::~a() {}
+
+   When main.cc is compiled, gcc only sees the constructor declaration, so
+   the constructor and hence the call to it are marked as exception throwing.
+   When a.cc is compiled, the body of the constructor is available and is
+   obviously not exception throwing. Thus DECL of a::a in a.o has the NOTHROW
+   attribute.  When LTO runs, two DECLs of a::a with different exception
+   attributes are merged.  We want the merged DECL to be not exception
+   throwing for better generated code.  To do that, we need to fix up any
+   function calls that have been marked as exception throwing.  */
+
+/* Fix up all the call statements whose target fndecls might have changed
+   to NOTHROW.   Note that this problem is not WPA specific.  We can also
+   run into this problem in normal LTO with multiple input files.  */
+
+void
+lto_fixup_nothrow_decls (void)
+{
+  struct cgraph_node *node;
+  struct cgraph_edge *edge;
+  struct function *caller_function;
+  gimple call_stmt;
+
+  /* Quit if we are in WPA mode or have not marked any DECLs.  */
+  if (flag_wpa || !lto_nothrow_fndecls)
+    return;
+
+  /* For each node that has been marked, go over all call edges to it.  */
+  for (node = cgraph_nodes; node; node = node->next)
+    if (bitmap_bit_p (lto_nothrow_fndecls, DECL_UID (node->decl)))
+      {
+	gcc_assert (TREE_NOTHROW (node->decl));
+	for (edge = node->callers; edge; edge = edge->next_caller)
+	  {
+	    caller_function = DECL_STRUCT_FUNCTION (edge->caller->decl);
+	    call_stmt = edge->call_stmt;
+	    gcc_assert (call_stmt);
+	    if (lookup_stmt_eh_lp_fn (caller_function, call_stmt) != 0)
+	      remove_stmt_from_eh_lp_fn (caller_function, call_stmt);
+	  }
+      }
+}
+
+/* Mark FNDECL as becoming not exception throwing.  */
+
+void
+lto_mark_nothrow_fndecl (tree fndecl)
+{
+  gcc_assert (TREE_CODE (fndecl) == FUNCTION_DECL);
+  if (!lto_nothrow_fndecls)
+    lto_nothrow_fndecls = lto_bitmap_alloc ();
+
+  bitmap_set_bit (lto_nothrow_fndecls, DECL_UID (fndecl));
+}
+
+/* Write out fix-up information.  Currently the only WPA fix-up
+   information is the list of DECLs marked as not exception throwing. SET
+   is a cgraph node set whose fix-up information is to be written.  */
+
+static void
+lto_output_wpa_fixup (cgraph_node_set set)
+{
+  struct lto_simple_output_block *ob;
+  cgraph_node_set_iterator csi;
+  tree fndecl;
+  bitmap seen_decls;
+  VEC(tree, heap) *decls = NULL;
+  unsigned HOST_WIDE_INT i, count;
+
+  ob = lto_create_simple_output_block (LTO_section_wpa_fixup);
+
+  /* Accumulate the DECLs to be written out.  Since we do not want
+     duplicates, we need to use a bitmap and a vector to save the
+     DECLs we want.  Note that we need to check if lto_nothrow_fndecls
+     is NULL.  This happens when no DECL has been marked.  */
+  seen_decls = lto_bitmap_alloc ();
+  if (lto_nothrow_fndecls)
+    for (csi = csi_start (set); !csi_end_p (csi); csi_next (&csi))
+      {
+	struct cgraph_edge *e;
+	struct cgraph_node *n;
+
+	n = csi_node (csi);
+	fndecl = n->decl;
+
+	/* Check if the N's function is in the set of nothrow functions.  */
+	if (!bitmap_bit_p (seen_decls, DECL_UID (fndecl)))
+	  {
+	    bitmap_set_bit (seen_decls, (DECL_UID (fndecl)));
+	    if (bitmap_bit_p (lto_nothrow_fndecls, DECL_UID (fndecl)))
+	      VEC_safe_push (tree, heap, decls, fndecl);
+	  }
+
+	/* Now check the callees and also add them if they are nothrow.  This
+	   is needed because node N may end up in a different partition than
+	   its callees.  In which case, when the file holding N is compiled,
+	   the calls it makes to nothrow functions will not be fixed up,
+	   causing verification issues.  */
+	for (e = n->callees; e; e = e->next_callee)
+	  {
+	    fndecl = e->callee->decl;
+	    if (!bitmap_bit_p (seen_decls, DECL_UID (fndecl)))
+	      {
+		bitmap_set_bit (seen_decls, (DECL_UID (fndecl)));
+		if (bitmap_bit_p (lto_nothrow_fndecls, DECL_UID (fndecl)))
+		  VEC_safe_push (tree, heap, decls, fndecl);
+	      }
+	  }
+      }
+
+  /* Write out number of DECLs, followed by the DECLs.  */
+  count = VEC_length (tree, decls);
+  lto_output_uleb128_stream (ob->main_stream, count);
+  for (i = 0; i < count; i++)
+    {
+      fndecl = VEC_index (tree, decls, i);
+      lto_output_fn_decl_index (ob->decl_state, ob->main_stream, fndecl);
+    }
+
+  /* Release resources.  */
+  lto_destroy_simple_output_block (ob);
+  VEC_free(tree, heap, decls);
+  lto_bitmap_free (seen_decls);
+}
+
+/* Read in WPA fix-up information from one file. FILE_DATA points to
+   DECL information of the file where as IB is the input block for the
+   WPA fix-up section.  */
+
+static void
+lto_input_wpa_fixup_1 (struct lto_file_decl_data *file_data,
+		   struct lto_input_block *ib)
+{
+  unsigned HOST_WIDE_INT i, count, decl_index;
+  tree fndecl;
+
+  count = lto_input_uleb128 (ib);
+  for (i = 0; i < count; i++)
+    {
+      decl_index = lto_input_uleb128 (ib);
+      fndecl = lto_file_decl_data_get_fn_decl (file_data, decl_index);
+      lto_mark_nothrow_fndecl (fndecl);
+    }
+}
+
+/* Read in WPA fix-up information. */
+
+static void
+lto_input_wpa_fixup (void)
+{
+  struct lto_file_decl_data ** file_data_vec
+    = lto_get_file_decl_data ();
+  struct lto_file_decl_data * file_data;
+  int i = 0;
+
+  /* Fix up information is only used in LTRANS mode.  */
+  if (!flag_ltrans)
+    return;
+
+  while ((file_data = file_data_vec[i++]))
+    {
+      const char *data;
+      size_t len;
+      struct lto_input_block *ib
+	= lto_create_simple_input_block (file_data, LTO_section_wpa_fixup,
+					 &data, &len);
+
+      lto_input_wpa_fixup_1 (file_data, ib);
+      lto_destroy_simple_input_block (file_data, LTO_section_wpa_fixup, ib,
+				      data, len);
+    }
+}
+
+/* Gate function for all lto streaming passes.  */
+
+static bool
+gate_wpa_fixup (void)
+{
+  return (flag_wpa || flag_ltrans) && gate_lto_out ();
+}
+
+struct ipa_opt_pass_d pass_ipa_lto_wpa_fixup =
+{
+ {
+  IPA_PASS,
+  "lto_wpa_fixup",			/* name */
+  gate_wpa_fixup,		        /* gate */
+  NULL,		                        /* execute */
+  NULL,					/* sub */
+  NULL,					/* next */
+  0,					/* static_pass_number */
+  TV_WHOPR_WPA_FIXUP,		        /* tv_id */
+  0,	                                /* properties_required */
+  0,					/* properties_provided */
+  0,					/* properties_destroyed */
+  0,            			/* todo_flags_start */
+  TODO_dump_func                        /* todo_flags_finish */
+ },
+ NULL,		                        /* generate_summary */
+ lto_output_wpa_fixup,			/* write_summary */
+ lto_input_wpa_fixup,			/* read_summary */
+ NULL,					/* function_read_summary */
+ NULL,					/* stmt_fixup */
+ 0,					/* TODOs */
+ NULL,			                /* function_transform */
+ NULL					/* variable_transform */
+};
+