Remove wpa-fixup pass

[Jan Hubicka <hubicka at ucw dot cz>]

Hi,
the WPA fixup pass is fixing call statements of functions that was found to be nothrow.
The same is done by fixup_cfg pass hidden in inliner's transform method.  So I've
removed WPA fixup pass since it is a lot more complex. This results in checking failure
because statement verifier avoids testing of throw flags only when cgraph_state
is IPA_SSA, while transfrom is called during expansion.
To avoid the problem I simply temporarily change cgraph state.  It is a hack,
but I guess it is better than introducing another state variable somewhere
or adding a flag in struct_function.

Bootstrapped/regtested x86_64-linux, OK?

Honza

	* timevar.def (TV_WHOPR_WPA_FIXUP): Remove.
	* lto-section-in.c (lto_section_name): Remove wpa_fixup.
	* lto-wpa-fixup.c: Remove.
	* Makefile.in (lto-wpa-fixup.o): Remove.
	* passes.c (init_optimization_passes): Remove pass_ipa_lto_wpa_fixup.
	(execute_all_ipa_transforms): Set cgraph_state to CGRAPH_STATE_IPA_SSA.
	* lto-streamer.c (lto_get_section_name): Remove wpa_fixup section.
	
	* lto/lto.c (lto_fixup_tree): Do not call wpa fixup.
	(materialize_cgraph): Likewise.
Index: timevar.def
===================================================================
--- timevar.def	(revision 158563)
+++ timevar.def	(working copy)
@@ -57,7 +57,6 @@ DEFTIMEVAR (TV_LTO                   , "
 DEFTIMEVAR (TV_WHOPR_WPA             , "whopr wpa")
 DEFTIMEVAR (TV_WHOPR_WPA_IO          , "whopr wpa I/O")
 DEFTIMEVAR (TV_WHOPR_LTRANS          , "whopr ltrans")
-DEFTIMEVAR (TV_WHOPR_WPA_FIXUP       , "whopr wpa fixup")
 DEFTIMEVAR (TV_WHOPR_WPA_LTRANS_EXEC , "whopr wpa->ltrans")
 DEFTIMEVAR (TV_IPA_REFERENCE         , "ipa reference")
 DEFTIMEVAR (TV_IPA_PURE_CONST        , "ipa pure const")
Index: lto-section-in.c
===================================================================
--- lto-section-in.c	(revision 158563)
+++ lto-section-in.c	(working copy)
@@ -55,7 +55,6 @@ const char *lto_section_name[LTO_N_SECTI
   "ipa_pure_const",
   "ipa_reference",
   "symtab",
-  "wpa_fixup",
   "opts"
 };
 
Index: lto-wpa-fixup.c
===================================================================
--- lto-wpa-fixup.c	(revision 158563)
+++ lto-wpa-fixup.c	(working copy)
@@ -1,282 +0,0 @@
-/* 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 */
-};
-
Index: lto/lto.c
===================================================================
--- lto/lto.c	(revision 158563)
+++ lto/lto.c	(working copy)
@@ -1560,28 +1561,6 @@ lto_fixup_tree (tree *tp, int *walk_subt
 
       if (t != prevailing)
 	{
-	  if (TREE_CODE (t) == FUNCTION_DECL
-	      && TREE_NOTHROW (prevailing) != TREE_NOTHROW (t))
-	    {
-	      /* If the prevailing definition does not throw but the
-		 declaration (T) was considered throwing, then we
-		 simply add PREVAILING to the list of throwing
-		 functions.  However, if the opposite is true, then
-		 the call to PREVAILING was generated assuming that
-		 the function didn't throw, which means that CFG
-		 cleanup may have removed surrounding try/catch
-		 regions.
-
-		 Note that we currently accept these cases even when
-		 they occur within a single file.  It's certainly a
-		 user error, but we silently allow the compiler to
-		 remove surrounding try/catch regions.  Perhaps we
-		 could emit a warning here, instead of silently
-		 accepting the conflicting declaration.  */
-	      if (TREE_NOTHROW (prevailing))
-		lto_mark_nothrow_fndecl (prevailing);
-	    }
-
 	   /* Also replace t with prevailing defintion.  We don't want to
 	      insert the other defintion in the seen set as we want to
 	      replace all instances of it.  */
@@ -1947,8 +1952,8 @@ materialize_cgraph (void)
   for (i = 0; VEC_iterate (tree, lto_global_var_decls, i, decl); i++)
     rest_of_decl_compilation (decl, 1, 0);
 
-  /* Fix up any calls to DECLs that have become not exception throwing.  */
-  lto_fixup_nothrow_decls ();
+  if (!quiet_flag)
+    fprintf (stderr, "\n");
 
   timevar_pop (lto_timer);
 }
Index: Makefile.in
===================================================================
--- Makefile.in	(revision 158563)
+++ Makefile.in	(working copy)
@@ -1258,7 +1258,6 @@ OBJS-common = \
 	lto-symtab.o \
 	lto-opts.o \
 	lto-streamer.o \
-	lto-wpa-fixup.o \
 	lto-compress.o \
 	mcf.o \
 	mode-switching.o \
@@ -2251,10 +2250,6 @@ lto-opts.o: lto-opts.c $(CONFIG_H) $(SYS
 lto-streamer.o: lto-streamer.c $(CONFIG_H) $(SYSTEM_H) coretypes.h   \
    $(TM_H) $(TREE_H) $(GIMPLE_H) $(BITMAP_H) $(LTO_STREAMER_H) $(FLAGS_H) \
    $(TREE_FLOW_H) $(DIAGNOSTIC_H) $(LTO_SYMTAB_H) $(TOPLEV_H)
-lto-wpa-fixup.o: lto-wpa-fixup.c $(CONFIG_H) $(SYSTEM_H) coretypes.h   \
-   $(TM_H) $(TOPLEV_H) $(TREE_H) $(EXPR_H) $(FLAGS_H) $(CGRAPH_H) \
-   $(FUNCTION_H) $(DIAGNOSTIC_H) $(BITMAP_H) $(TIMEVAR_H) \
-   $(TREE_FLOW_H) $(TREE_PASS_H) $(LTO_STREAMER_H)
 langhooks.o : langhooks.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) \
    $(TREE_H) $(TOPLEV_H) $(TREE_INLINE_H) $(RTL_H) insn-config.h $(INTEGRATE_H) \
    langhooks.h $(TARGET_H) $(LANGHOOKS_DEF_H) $(FLAGS_H) $(GGC_H) $(DIAGNOSTIC_H) \
Index: passes.c
===================================================================
--- passes.c	(revision 158563)
+++ passes.c	(working copy)
@@ -814,7 +814,6 @@ init_optimization_passes (void)
 
   p = &all_lto_gen_passes;
   NEXT_PASS (pass_ipa_lto_gimple_out);
-  NEXT_PASS (pass_ipa_lto_wpa_fixup);
   NEXT_PASS (pass_ipa_lto_finish_out);  /* This must be the last LTO pass.  */
   *p = NULL;
 
@@ -1487,10 +1486,20 @@ execute_one_ipa_transform_pass (struct c
 void
 execute_all_ipa_transforms (void)
 {
+  enum cgraph_state old_state = cgraph_state;
   struct cgraph_node *node;
   if (!cfun)
     return;
   node = cgraph_node (current_function_decl);
+
+  /* Statement verification skip verification of nothorw when
+     state is IPA_SSA because we do not modify function bodies
+     after setting the flag on function.  Instead we leave it
+     to fixup_cfg to do such a transformation.  We need to temporarily
+     change the cgraph state so statement verifier before
+     transform do not fire.  */
+  cgraph_state = CGRAPH_STATE_IPA_SSA;
+
   if (node->ipa_transforms_to_apply)
     {
       unsigned int i;
@@ -1504,6 +1513,7 @@ execute_all_ipa_transforms (void)
       VEC_free (ipa_opt_pass, heap, node->ipa_transforms_to_apply);
       node->ipa_transforms_to_apply = NULL;
     }
+  cgraph_state = old_state;
 }
 
 /* Execute PASS. */
Index: lto-streamer.c
===================================================================
--- lto-streamer.c	(revision 158563)
+++ lto-streamer.c	(working copy)
@@ -169,9 +169,6 @@ lto_get_section_name (int section_type, 
     case LTO_section_ipa_reference:
       return concat (LTO_SECTION_NAME_PREFIX, ".reference", NULL);
 
-    case LTO_section_wpa_fixup:
-      return concat (LTO_SECTION_NAME_PREFIX, ".wpa_fixup", NULL);
-
     case LTO_section_opts:
       return concat (LTO_SECTION_NAME_PREFIX, ".opts", NULL);