gcc/cp/optimize.c

/* Perform optimizations on tree structure.
   Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004
   Free Software Foundation, Inc.
   Written by Mark Michell (mark@codesourcery.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 2, 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 COPYING.  If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "cp-tree.h"
#include "rtl.h"
#include "insn-config.h"
#include "input.h"
#include "integrate.h"
#include "toplev.h"
#include "varray.h"
#include "params.h"
#include "hashtab.h"
#include "debug.h"
#include "tree-inline.h"

/* Prototypes.  */

static tree calls_setjmp_r (tree *, int *, void *);
static void update_cloned_parm (tree, tree);
static void dump_function (enum tree_dump_index, tree);

/* Optimize the body of FN.  */

void
optimize_function (tree fn)
{
  dump_function (TDI_original, fn);

  if (flag_inline_trees
      /* We do not inline thunks, as (a) the backend tries to optimize
         the call to the thunkee, (b) tree based inlining breaks that
         optimization, (c) virtual functions are rarely inlineable,
         and (d) TARGET_ASM_OUTPUT_MI_THUNK is there to DTRT anyway.  */
      && !DECL_THUNK_P (fn))
    {
      optimize_inline_calls (fn);
      dump_function (TDI_inlined, fn);
    }
  
  dump_function (TDI_optimized, fn);
}

/* Called from calls_setjmp_p via walk_tree.  */

static tree
calls_setjmp_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
                void *data ATTRIBUTE_UNUSED)
{
  /* We're only interested in FUNCTION_DECLS.  */
  if (TREE_CODE (*tp) != FUNCTION_DECL)
    return NULL_TREE;

  return setjmp_call_p (*tp) ? *tp : NULL_TREE;
}

/* Returns nonzero if FN calls `setjmp' or some other function that
   can return more than once.  This function is conservative; it may
   occasionally return a nonzero value even when FN does not actually
   call `setjmp'.  */

bool
calls_setjmp_p (tree fn)
{
  return walk_tree_without_duplicates (&DECL_SAVED_TREE (fn),
				       calls_setjmp_r,
				       NULL) != NULL_TREE;
}

/* CLONED_PARM is a copy of CLONE, generated for a cloned constructor
   or destructor.  Update it to ensure that the source-position for
   the cloned parameter matches that for the original, and that the
   debugging generation code will be able to find the original PARM.  */

static void
update_cloned_parm (tree parm, tree cloned_parm)
{
  DECL_ABSTRACT_ORIGIN (cloned_parm) = parm;

  /* We may have taken its address.  */
  TREE_ADDRESSABLE (cloned_parm) = TREE_ADDRESSABLE (parm);

  /* The definition might have different constness.  */
  TREE_READONLY (cloned_parm) = TREE_READONLY (parm);
  
  TREE_USED (cloned_parm) = TREE_USED (parm);
  
  /* The name may have changed from the declaration.  */
  DECL_NAME (cloned_parm) = DECL_NAME (parm);
  DECL_SOURCE_LOCATION (cloned_parm) = DECL_SOURCE_LOCATION (parm);
}

/* FN is a function that has a complete body.  Clone the body as
   necessary.  Returns nonzero if there's no longer any need to
   process the main body.  */

bool
maybe_clone_body (tree fn)
{
  tree clone;

  /* We only clone constructors and destructors.  */
  if (!DECL_MAYBE_IN_CHARGE_CONSTRUCTOR_P (fn)
      && !DECL_MAYBE_IN_CHARGE_DESTRUCTOR_P (fn))
    return 0;

  /* Emit the DWARF1 abstract instance.  */
  (*debug_hooks->deferred_inline_function) (fn);

  /* We know that any clones immediately follow FN in the TYPE_METHODS
     list.  */
  for (clone = TREE_CHAIN (fn);
       clone && DECL_CLONED_FUNCTION_P (clone);
       clone = TREE_CHAIN (clone))
    {
      tree parm;
      tree clone_parm;
      int parmno;
      splay_tree decl_map;

      /* Update CLONE's source position information to match FN's.  */
      DECL_SOURCE_LOCATION (clone) = DECL_SOURCE_LOCATION (fn);
      DECL_INLINE (clone) = DECL_INLINE (fn);
      DECL_DECLARED_INLINE_P (clone) = DECL_DECLARED_INLINE_P (fn);
      DECL_COMDAT (clone) = DECL_COMDAT (fn);
      DECL_WEAK (clone) = DECL_WEAK (fn);
      DECL_ONE_ONLY (clone) = DECL_ONE_ONLY (fn);
      DECL_SECTION_NAME (clone) = DECL_SECTION_NAME (fn);
      DECL_USE_TEMPLATE (clone) = DECL_USE_TEMPLATE (fn);
      DECL_EXTERNAL (clone) = DECL_EXTERNAL (fn);
      DECL_INTERFACE_KNOWN (clone) = DECL_INTERFACE_KNOWN (fn);
      DECL_NOT_REALLY_EXTERN (clone) = DECL_NOT_REALLY_EXTERN (fn);
      TREE_PUBLIC (clone) = TREE_PUBLIC (fn);
      DECL_VISIBILITY (clone) = DECL_VISIBILITY (fn);

      /* Adjust the parameter names and locations.  */
      parm = DECL_ARGUMENTS (fn);
      clone_parm = DECL_ARGUMENTS (clone);
      /* Update the `this' parameter, which is always first.  */
      update_cloned_parm (parm, clone_parm);
      parm = TREE_CHAIN (parm);
      clone_parm = TREE_CHAIN (clone_parm);
      if (DECL_HAS_IN_CHARGE_PARM_P (fn))
	parm = TREE_CHAIN (parm);
      if (DECL_HAS_VTT_PARM_P (fn))
	parm = TREE_CHAIN (parm);
      if (DECL_HAS_VTT_PARM_P (clone))
	clone_parm = TREE_CHAIN (clone_parm);
      for (; parm;
	   parm = TREE_CHAIN (parm), clone_parm = TREE_CHAIN (clone_parm))
	/* Update this parameter.  */
	update_cloned_parm (parm, clone_parm);

      /* Start processing the function.  */
      push_to_top_level ();
      start_function (NULL_TREE, clone, NULL_TREE, SF_PRE_PARSED);

      /* Remap the parameters.  */
      decl_map = splay_tree_new (splay_tree_compare_pointers, NULL, NULL);
      for (parmno = 0,
	     parm = DECL_ARGUMENTS (fn),
	     clone_parm = DECL_ARGUMENTS (clone);
	   parm;
	   ++parmno,
	     parm = TREE_CHAIN (parm))
	{
	  /* Map the in-charge parameter to an appropriate constant.  */
	  if (DECL_HAS_IN_CHARGE_PARM_P (fn) && parmno == 1)
	    {
	      tree in_charge;
	      in_charge = in_charge_arg_for_name (DECL_NAME (clone));
	      splay_tree_insert (decl_map,
				 (splay_tree_key) parm,
				 (splay_tree_value) in_charge);
	    }
	  else if (DECL_ARTIFICIAL (parm)
		   && DECL_NAME (parm) == vtt_parm_identifier)
	    {
	      /* For a subobject constructor or destructor, the next
		 argument is the VTT parameter.  Remap the VTT_PARM
		 from the CLONE to this parameter.  */
	      if (DECL_HAS_VTT_PARM_P (clone))
		{
		  DECL_ABSTRACT_ORIGIN (clone_parm) = parm;
		  splay_tree_insert (decl_map,
				     (splay_tree_key) parm,
				     (splay_tree_value) clone_parm);
		  clone_parm = TREE_CHAIN (clone_parm);
		}
	      /* Otherwise, map the VTT parameter to `NULL'.  */
	      else
		{
		  splay_tree_insert (decl_map,
				     (splay_tree_key) parm,
				     (splay_tree_value) null_pointer_node);
		}
	    }
	  /* Map other parameters to their equivalents in the cloned
	     function.  */
	  else
	    {
	      splay_tree_insert (decl_map,
				 (splay_tree_key) parm,
				 (splay_tree_value) clone_parm);
	      clone_parm = TREE_CHAIN (clone_parm);
	    }
	}

      /* Clone the body.  */
      clone_body (clone, fn, decl_map);

      /* Clean up.  */
      splay_tree_delete (decl_map);

      /* The clone can throw iff the original function can throw.  */
      cp_function_chain->can_throw = !TREE_NOTHROW (fn);

      /* Now, expand this function into RTL, if appropriate.  */
      finish_function (0);
      BLOCK_ABSTRACT_ORIGIN (DECL_INITIAL (clone)) = DECL_INITIAL (fn);
      expand_or_defer_fn (clone);
      pop_from_top_level ();
    }

  /* We don't need to process the original function any further.  */
  return 1;
}

/* Dump FUNCTION_DECL FN as tree dump PHASE.  */

static void
dump_function (enum tree_dump_index phase, tree fn)
{
  FILE *stream;
  int flags;

  stream = dump_begin (phase, &flags);
  if (stream)
    {
      fprintf (stream, "\n;; Function %s",
	       decl_as_string (fn, TFF_DECL_SPECIFIERS));
      fprintf (stream, " (%s)\n",
	       decl_as_string (DECL_ASSEMBLER_NAME (fn), 0));
      fprintf (stream, ";; enabled by -fdump-%s\n", dump_flag_name (phase));
      fprintf (stream, "\n");
      
      dump_node (fn, TDF_SLIM | flags, stream);
      dump_end (phase, stream);
    }
}