commit gcc-4.4.3 which is used to build gcc-4.4.3 Android toolchain in master.

The source is based on fsf gcc-4.4.3 and contains local patches which
are recorded in gcc-4.4.3/README.google.

Change-Id: Id8c6d6927df274ae9749196a1cc24dbd9abc9887

1 files changed, 1162 insertions, 0 deletions

diff --git a/gcc-4.4.3/gcc/dce.c b/gcc-4.4.3/gcc/dce.c
new file mode 100644
index 000000000..f6a10d619
--- /dev/null
+++ b/gcc-4.4.3/gcc/dce.c
@@ -0,0 +1,1162 @@
+/* RTL dead code elimination.
+   Copyright (C) 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
+
+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 "hashtab.h"
+#include "tm.h"
+#include "rtl.h"
+#include "tree.h"
+#include "regs.h"
+#include "hard-reg-set.h"
+#include "flags.h"
+#include "df.h"
+#include "cselib.h"
+#include "dce.h"
+#include "timevar.h"
+#include "tree-pass.h"
+#include "dbgcnt.h"
+#include "tm_p.h"
+
+DEF_VEC_I(int);
+DEF_VEC_ALLOC_I(int,heap);
+
+
+/* -------------------------------------------------------------------------
+   Core mark/delete routines
+   ------------------------------------------------------------------------- */
+
+/* True if we are invoked while the df engine is running; in this case,
+   we don't want to reenter it.  */
+static bool df_in_progress = false;
+
+/* Instructions that have been marked but whose dependencies have not
+   yet been processed.  */
+static VEC(rtx,heap) *worklist;
+
+/* Bitmap of instructions marked as needed indexed by INSN_UID.  */
+static sbitmap marked;
+
+/* Bitmap obstacks used for block processing by the fast algorithm.  */
+static bitmap_obstack dce_blocks_bitmap_obstack;
+static bitmap_obstack dce_tmp_bitmap_obstack;
+
+static bool find_call_stack_args (rtx, bool, bool, bitmap);
+
+/* A subroutine for which BODY is part of the instruction being tested;
+   either the top-level pattern, or an element of a PARALLEL.  The
+   instruction is known not to be a bare USE or CLOBBER.  */
+
+static bool
+deletable_insn_p_1 (rtx body)
+{
+  switch (GET_CODE (body))
+    {
+    case PREFETCH:
+    case TRAP_IF:
+      /* The UNSPEC case was added here because the ia-64 claims that
+	 USEs do not work after reload and generates UNSPECS rather
+	 than USEs.  Since dce is run after reload we need to avoid
+	 deleting these even if they are dead.  If it turns out that
+	 USEs really do work after reload, the ia-64 should be
+	 changed, and the UNSPEC case can be removed.  */
+    case UNSPEC:
+      return false;
+
+    default:
+      if (volatile_refs_p (body))
+	return false;
+
+      if (flag_non_call_exceptions && may_trap_p (body))
+	return false;
+
+      return true;
+    }
+}
+
+
+/* Return true if INSN is a normal instruction that can be deleted by
+   the DCE pass.  */
+
+static bool
+deletable_insn_p (rtx insn, bool fast, bitmap arg_stores)
+{
+  rtx body, x;
+  int i;
+
+  if (CALL_P (insn)
+      /* We cannot delete calls inside of the recursive dce because
+	 this may cause basic blocks to be deleted and this messes up
+	 the rest of the stack of optimization passes.  */
+      && (!df_in_progress)
+      /* We cannot delete pure or const sibling calls because it is
+	 hard to see the result.  */
+      && (!SIBLING_CALL_P (insn))
+      /* We can delete dead const or pure calls as long as they do not
+         infinite loop.  */
+      && (RTL_CONST_OR_PURE_CALL_P (insn)
+	  && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn)))
+    return find_call_stack_args (insn, false, fast, arg_stores);
+
+  if (!NONJUMP_INSN_P (insn))
+    return false;
+
+  body = PATTERN (insn);
+  switch (GET_CODE (body))
+    {
+    case USE:
+      return false;
+
+    case CLOBBER:
+      if (fast)
+	{
+	  /* A CLOBBER of a dead pseudo register serves no purpose.
+	     That is not necessarily true for hard registers until
+	     after reload.  */
+	  x = XEXP (body, 0);
+	  return REG_P (x) && (!HARD_REGISTER_P (x) || reload_completed);
+	}
+      else
+	/* Because of the way that use-def chains are built, it is not
+	   possible to tell if the clobber is dead because it can
+	   never be the target of a use-def chain.  */
+	return false;
+
+    case PARALLEL:
+      for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
+	if (!deletable_insn_p_1 (XVECEXP (body, 0, i)))
+	  return false;
+      return true;
+
+    default:
+      return deletable_insn_p_1 (body);
+    }
+}
+
+
+/* Return true if INSN has been marked as needed.  */
+
+static inline int
+marked_insn_p (rtx insn)
+{
+  /* Artificial defs are always needed and they do not have an insn.
+     We should never see them here.  */
+  gcc_assert (insn);
+  return TEST_BIT (marked, INSN_UID (insn));
+}
+
+
+/* If INSN has not yet been marked as needed, mark it now, and add it to
+   the worklist.  */
+
+static void
+mark_insn (rtx insn, bool fast)
+{
+  if (!marked_insn_p (insn))
+    {
+      if (!fast)
+	VEC_safe_push (rtx, heap, worklist, insn);
+      SET_BIT (marked, INSN_UID (insn));
+      if (dump_file)
+	fprintf (dump_file, "  Adding insn %d to worklist\n", INSN_UID (insn));
+      if (CALL_P (insn)
+	  && !df_in_progress
+	  && !SIBLING_CALL_P (insn)
+	  && (RTL_CONST_OR_PURE_CALL_P (insn)
+	      && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn)))
+	find_call_stack_args (insn, true, fast, NULL);
+    }
+}
+
+
+/* A note_stores callback used by mark_nonreg_stores.  DATA is the
+   instruction containing DEST.  */
+
+static void
+mark_nonreg_stores_1 (rtx dest, const_rtx pattern, void *data)
+{
+  if (GET_CODE (pattern) != CLOBBER && !REG_P (dest))
+    mark_insn ((rtx) data, true);
+}
+
+
+/* A note_stores callback used by mark_nonreg_stores.  DATA is the
+   instruction containing DEST.  */
+
+static void
+mark_nonreg_stores_2 (rtx dest, const_rtx pattern, void *data)
+{
+  if (GET_CODE (pattern) != CLOBBER && !REG_P (dest))
+    mark_insn ((rtx) data, false);
+}
+
+
+/* Mark INSN if BODY stores to a non-register destination.  */
+
+static void
+mark_nonreg_stores (rtx body, rtx insn, bool fast)
+{
+  if (fast)
+    note_stores (body, mark_nonreg_stores_1, insn);
+  else
+    note_stores (body, mark_nonreg_stores_2, insn);
+}
+
+
+/* Try to find all stack stores of CALL_INSN arguments if
+   ACCUMULATE_OUTGOING_ARGS.  If all stack stores have been found
+   and it is therefore safe to eliminate the call, return true,
+   otherwise return false.  This function should be first called
+   with DO_MARK false, and only when the CALL_INSN is actually
+   going to be marked called again with DO_MARK true.  */
+
+static bool
+find_call_stack_args (rtx call_insn, bool do_mark, bool fast,
+		      bitmap arg_stores)
+{
+  rtx p, insn, prev_insn;
+  bool ret;
+  HOST_WIDE_INT min_sp_off, max_sp_off;
+  bitmap sp_bytes;
+
+  gcc_assert (CALL_P (call_insn));
+  if (!ACCUMULATE_OUTGOING_ARGS)
+    return true;
+
+  if (!do_mark)
+    {
+      gcc_assert (arg_stores);
+      bitmap_clear (arg_stores);
+    }
+
+  min_sp_off = INTTYPE_MAXIMUM (HOST_WIDE_INT);
+  max_sp_off = 0;
+
+  /* First determine the minimum and maximum offset from sp for
+     stored arguments.  */
+  for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1))
+    if (GET_CODE (XEXP (p, 0)) == USE
+	&& MEM_P (XEXP (XEXP (p, 0), 0)))
+      {
+	rtx mem = XEXP (XEXP (p, 0), 0), addr, size;
+	HOST_WIDE_INT off = 0;
+	size = MEM_SIZE (mem);
+	if (size == NULL_RTX)
+	  return false;
+	addr = XEXP (mem, 0);
+	if (GET_CODE (addr) == PLUS
+	    && REG_P (XEXP (addr, 0))
+	    && CONST_INT_P (XEXP (addr, 1)))
+	  {
+	    off = INTVAL (XEXP (addr, 1));
+	    addr = XEXP (addr, 0);
+	  }
+	if (addr != stack_pointer_rtx)
+	  {
+	    if (!REG_P (addr))
+	      return false;
+	    /* If not fast, use chains to see if addr wasn't set to
+	       sp + offset.  */
+	    if (!fast)
+	      {
+		df_ref *use_rec;
+		struct df_link *defs;
+		rtx set;
+
+		for (use_rec = DF_INSN_USES (call_insn); *use_rec; use_rec++)
+		  if (rtx_equal_p (addr, DF_REF_REG (*use_rec)))
+		    break;
+
+		if (*use_rec == NULL)
+		  return false;
+
+		for (defs = DF_REF_CHAIN (*use_rec); defs; defs = defs->next)
+		  if (! DF_REF_IS_ARTIFICIAL (defs->ref))
+		    break;
+
+		if (defs == NULL)
+		  return false;
+
+		set = single_set (DF_REF_INSN (defs->ref));
+		if (!set)
+		  return false;
+
+		if (GET_CODE (SET_SRC (set)) != PLUS
+		    || XEXP (SET_SRC (set), 0) != stack_pointer_rtx
+		    || !CONST_INT_P (XEXP (SET_SRC (set), 1)))
+		  return false;
+
+		off += INTVAL (XEXP (SET_SRC (set), 1));
+	      }
+	    else
+	      return false;
+	  }
+	min_sp_off = MIN (min_sp_off, off);
+	max_sp_off = MAX (max_sp_off, off + INTVAL (size));
+      }
+
+  if (min_sp_off >= max_sp_off)
+    return true;
+  sp_bytes = BITMAP_ALLOC (NULL);
+
+  /* Set bits in SP_BYTES bitmap for bytes relative to sp + min_sp_off
+     which contain arguments.  Checking has been done in the previous
+     loop.  */
+  for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1))
+    if (GET_CODE (XEXP (p, 0)) == USE
+	&& MEM_P (XEXP (XEXP (p, 0), 0)))
+      {
+	rtx mem = XEXP (XEXP (p, 0), 0), addr;
+	HOST_WIDE_INT off = 0, byte;
+	addr = XEXP (mem, 0);
+	if (GET_CODE (addr) == PLUS
+	    && REG_P (XEXP (addr, 0))
+	    && CONST_INT_P (XEXP (addr, 1)))
+	  {
+	    off = INTVAL (XEXP (addr, 1));
+	    addr = XEXP (addr, 0);
+	  }
+	if (addr != stack_pointer_rtx)
+	  {
+	    df_ref *use_rec;
+	    struct df_link *defs;
+	    rtx set;
+
+	    for (use_rec = DF_INSN_USES (call_insn); *use_rec; use_rec++)
+	      if (rtx_equal_p (addr, DF_REF_REG (*use_rec)))
+		break;
+
+	    for (defs = DF_REF_CHAIN (*use_rec); defs; defs = defs->next)
+	      if (! DF_REF_IS_ARTIFICIAL (defs->ref))
+		break;
+
+	    set = single_set (DF_REF_INSN (defs->ref));
+	    off += INTVAL (XEXP (SET_SRC (set), 1));
+	  }
+	for (byte = off; byte < off + INTVAL (MEM_SIZE (mem)); byte++)
+	  {
+	    gcc_assert (!bitmap_bit_p (sp_bytes, byte - min_sp_off));
+	    bitmap_set_bit (sp_bytes, byte - min_sp_off);
+	  }
+      }
+
+  /* Walk backwards, looking for argument stores.  The search stops
+     when seeing another call, sp adjustment or memory store other than
+     argument store.  */
+  ret = false;
+  for (insn = PREV_INSN (call_insn); insn; insn = prev_insn)
+    {
+      rtx set, mem, addr;
+      HOST_WIDE_INT off, byte;
+
+      if (insn == BB_HEAD (BLOCK_FOR_INSN (call_insn)))
+	prev_insn = NULL_RTX;
+      else
+	prev_insn = PREV_INSN (insn);
+
+      if (CALL_P (insn))
+	break;
+
+      if (!INSN_P (insn))
+	continue;
+
+      set = single_set (insn);
+      if (!set || SET_DEST (set) == stack_pointer_rtx)
+	break;
+
+      if (!MEM_P (SET_DEST (set)))
+	continue;
+
+      mem = SET_DEST (set);
+      addr = XEXP (mem, 0);
+      off = 0;
+      if (GET_CODE (addr) == PLUS
+	  && REG_P (XEXP (addr, 0))
+	  && CONST_INT_P (XEXP (addr, 1)))
+	{
+	  off = INTVAL (XEXP (addr, 1));
+	  addr = XEXP (addr, 0);
+	}
+      if (addr != stack_pointer_rtx)
+	{
+	  if (!REG_P (addr))
+	    break;
+	  if (!fast)
+	    {
+	      df_ref *use_rec;
+	      struct df_link *defs;
+	      rtx set;
+
+	      for (use_rec = DF_INSN_USES (insn); *use_rec; use_rec++)
+		if (rtx_equal_p (addr, DF_REF_REG (*use_rec)))
+		  break;
+
+	      if (*use_rec == NULL)
+		break;
+
+	      for (defs = DF_REF_CHAIN (*use_rec); defs; defs = defs->next)
+		if (! DF_REF_IS_ARTIFICIAL (defs->ref))
+		  break;
+
+	      if (defs == NULL)
+		break;
+
+	      set = single_set (DF_REF_INSN (defs->ref));
+	      if (!set)
+		break;
+
+	      if (GET_CODE (SET_SRC (set)) != PLUS
+		  || XEXP (SET_SRC (set), 0) != stack_pointer_rtx
+		  || !CONST_INT_P (XEXP (SET_SRC (set), 1)))
+		break;
+
+	      off += INTVAL (XEXP (SET_SRC (set), 1));
+	    }
+	  else
+	    break;
+	}
+
+      if (GET_MODE_SIZE (GET_MODE (mem)) == 0)
+	break;
+
+      for (byte = off; byte < off + GET_MODE_SIZE (GET_MODE (mem)); byte++)
+	{
+	  if (byte < min_sp_off
+	      || byte >= max_sp_off
+	      || !bitmap_bit_p (sp_bytes, byte - min_sp_off))
+	    break;
+	  bitmap_clear_bit (sp_bytes, byte - min_sp_off);
+	}
+
+      if (!deletable_insn_p (insn, fast, NULL))
+	break;
+
+      if (do_mark)
+	mark_insn (insn, fast);
+      else
+	bitmap_set_bit (arg_stores, INSN_UID (insn));
+
+      if (bitmap_empty_p (sp_bytes))
+	{
+	  ret = true;
+	  break;
+	}
+    }
+
+  BITMAP_FREE (sp_bytes);
+  if (!ret && arg_stores)
+    bitmap_clear (arg_stores);
+
+  return ret;
+}
+
+
+/* Delete all REG_EQUAL notes of the registers INSN writes, to prevent
+   bad dangling REG_EQUAL notes. */
+
+static void
+delete_corresponding_reg_eq_notes (rtx insn)
+{
+  df_ref *def_rec;
+  for (def_rec = DF_INSN_DEFS (insn); *def_rec; def_rec++)
+    {
+      df_ref def = *def_rec;
+      unsigned int regno = DF_REF_REGNO (def);
+      /* This loop is a little tricky.  We cannot just go down the
+	 chain because it is being modified by the actions in the
+	 loop.  So we just get the head.  We plan to drain the list
+	 anyway.  */
+      while (DF_REG_EQ_USE_CHAIN (regno))
+	{
+	  df_ref eq_use = DF_REG_EQ_USE_CHAIN (regno);
+	  rtx noted_insn = DF_REF_INSN (eq_use);
+	  rtx note = find_reg_note (noted_insn, REG_EQUAL, NULL_RTX);
+	  if (!note)
+	    note = find_reg_note (noted_insn, REG_EQUIV, NULL_RTX);
+
+	  /* This assert is generally triggered when someone deletes a
+	     REG_EQUAL or REG_EQUIV note by hacking the list manually
+	     rather than calling remove_note.  */
+	  gcc_assert (note);
+	  remove_note (noted_insn, note);
+	}
+    }
+}
+
+
+/* Delete every instruction that hasn't been marked.  */
+
+static void
+delete_unmarked_insns (void)
+{
+  basic_block bb;
+  rtx insn, next;
+  bool must_clean = false;
+
+  FOR_EACH_BB_REVERSE (bb)
+    FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next)
+      if (INSN_P (insn))
+	{
+	  /* Always delete no-op moves.  */
+	  if (noop_move_p (insn))
+	    ;
+
+	  /* Otherwise rely only on the DCE algorithm.  */
+	  else if (marked_insn_p (insn))
+	    continue;
+
+	  /* Beware that reaching a dbg counter limit here can result
+	     in miscompiled file.  This occurs when a group of insns
+	     must be deleted together, typically because the kept insn
+	     depends on the output from the deleted insn.  Deleting
+	     this insns in reverse order (both at the bb level and
+	     when looking at the blocks) minimizes this, but does not
+	     eliminate it, since it is possible for the using insn to
+	     be top of a block and the producer to be at the bottom of
+	     the block.  However, in most cases this will only result
+	     in an uninitialized use of an insn that is dead anyway.
+
+	     However, there is one rare case that will cause a
+	     miscompile: deletion of non-looping pure and constant
+	     calls on a machine where ACCUMULATE_OUTGOING_ARGS is true.
+	     In this case it is possible to remove the call, but leave
+	     the argument pushes to the stack.  Because of the changes
+	     to the stack pointer, this will almost always lead to a
+	     miscompile.  */
+	  if (!dbg_cnt (dce))
+	    continue;
+
+	  if (dump_file)
+	    fprintf (dump_file, "DCE: Deleting insn %d\n", INSN_UID (insn));
+
+	  /* Before we delete the insn we have to delete REG_EQUAL notes
+	     for the destination regs in order to avoid dangling notes.  */
+	  delete_corresponding_reg_eq_notes (insn);
+
+	  /* If a pure or const call is deleted, this may make the cfg
+	     have unreachable blocks.  We rememeber this and call
+	     delete_unreachable_blocks at the end.  */
+	  if (CALL_P (insn))
+	    must_clean = true;
+
+	  /* Now delete the insn.  */
+	  delete_insn_and_edges (insn);
+	}
+
+  /* Deleted a pure or const call.  */
+  if (must_clean)
+    delete_unreachable_blocks ();
+}
+
+
+/* Go through the instructions and mark those whose necessity is not
+   dependent on inter-instruction information.  Make sure all other
+   instructions are not marked.  */
+
+static void
+prescan_insns_for_dce (bool fast)
+{
+  basic_block bb;
+  rtx insn, prev;
+  bitmap arg_stores = NULL;
+
+  if (dump_file)
+    fprintf (dump_file, "Finding needed instructions:\n");
+
+  if (!df_in_progress && ACCUMULATE_OUTGOING_ARGS)
+    arg_stores = BITMAP_ALLOC (NULL);
+
+  FOR_EACH_BB (bb)
+    {
+      FOR_BB_INSNS_REVERSE_SAFE (bb, insn, prev)
+	if (INSN_P (insn))
+	  {
+	    /* Don't mark argument stores now.  They will be marked
+	       if needed when the associated CALL is marked.  */
+	    if (arg_stores && bitmap_bit_p (arg_stores, INSN_UID (insn)))
+	      continue;
+	    if (deletable_insn_p (insn, fast, arg_stores))
+	      mark_nonreg_stores (PATTERN (insn), insn, fast);
+	    else
+	      mark_insn (insn, fast);
+	  }
+      /* find_call_stack_args only looks at argument stores in the
+	 same bb.  */
+      if (arg_stores)
+	bitmap_clear (arg_stores);
+    }
+
+  if (arg_stores)
+    BITMAP_FREE (arg_stores);
+
+  if (dump_file)
+    fprintf (dump_file, "Finished finding needed instructions:\n");
+}
+
+
+/* UD-based DSE routines. */
+
+/* Mark instructions that define artificially-used registers, such as
+   the frame pointer and the stack pointer.  */
+
+static void
+mark_artificial_uses (void)
+{
+  basic_block bb;
+  struct df_link *defs;
+  df_ref *use_rec;
+
+  FOR_ALL_BB (bb)
+    {
+      for (use_rec = df_get_artificial_uses (bb->index); 
+	   *use_rec; use_rec++)
+	for (defs = DF_REF_CHAIN (*use_rec); defs; defs = defs->next)
+	  if (! DF_REF_IS_ARTIFICIAL (defs->ref))
+	    mark_insn (DF_REF_INSN (defs->ref), false);
+    }
+}
+
+
+/* Mark every instruction that defines a register value that INSN uses.  */
+
+static void
+mark_reg_dependencies (rtx insn)
+{
+  struct df_link *defs;
+  df_ref *use_rec;
+
+  for (use_rec = DF_INSN_USES (insn); *use_rec; use_rec++)
+    {
+      df_ref use = *use_rec;
+      if (dump_file)
+	{
+	  fprintf (dump_file, "Processing use of ");
+	  print_simple_rtl (dump_file, DF_REF_REG (use));
+	  fprintf (dump_file, " in insn %d:\n", INSN_UID (insn));
+	}
+      for (defs = DF_REF_CHAIN (use); defs; defs = defs->next)
+	if (! DF_REF_IS_ARTIFICIAL (defs->ref))
+	  mark_insn (DF_REF_INSN (defs->ref), false);
+    }
+}
+
+
+/* Initialize global variables for a new DCE pass.  */
+
+static void
+init_dce (bool fast)
+{
+  if (!df_in_progress)
+    {
+      if (!fast)
+	df_chain_add_problem (DF_UD_CHAIN);
+      df_analyze ();
+    }
+
+  if (dump_file)
+    df_dump (dump_file);
+
+  if (fast)
+    {
+      bitmap_obstack_initialize (&dce_blocks_bitmap_obstack);
+      bitmap_obstack_initialize (&dce_tmp_bitmap_obstack);
+    }
+
+  marked = sbitmap_alloc (get_max_uid () + 1);
+  sbitmap_zero (marked);
+}
+
+
+/* Free the data allocated by init_dce.  */
+
+static void
+fini_dce (bool fast)
+{
+  sbitmap_free (marked);
+
+  if (fast)
+    {
+      bitmap_obstack_release (&dce_blocks_bitmap_obstack);
+      bitmap_obstack_release (&dce_tmp_bitmap_obstack);
+    }
+}
+
+
+/* UD-chain based DCE.  */
+
+static unsigned int
+rest_of_handle_ud_dce (void)
+{
+  rtx insn;
+
+  init_dce (false);
+
+  prescan_insns_for_dce (false);
+  mark_artificial_uses ();
+  while (VEC_length (rtx, worklist) > 0)
+    {
+      insn = VEC_pop (rtx, worklist);
+      mark_reg_dependencies (insn);
+    }
+  VEC_free (rtx, heap, worklist);
+
+  /* Before any insns are deleted, we must remove the chains since
+     they are not bidirectional.  */
+  df_remove_problem (df_chain);
+  delete_unmarked_insns ();
+
+  fini_dce (false);
+  return 0;
+}
+
+
+static bool
+gate_ud_dce (void)
+{
+  return optimize > 1 && flag_dce
+    && dbg_cnt (dce_ud);
+}
+
+struct rtl_opt_pass pass_ud_rtl_dce =
+{
+ {
+  RTL_PASS,
+  "dce",                                /* name */
+  gate_ud_dce,                        /* gate */
+  rest_of_handle_ud_dce,              /* execute */
+  NULL,                                 /* sub */
+  NULL,                                 /* next */
+  0,                                    /* static_pass_number */
+  TV_DCE,                               /* tv_id */
+  0,                                    /* properties_required */
+  0,                                    /* properties_provided */
+  0,                                    /* properties_destroyed */
+  0,                                    /* todo_flags_start */
+  TODO_dump_func |
+  TODO_df_finish | TODO_verify_rtl_sharing |
+  TODO_ggc_collect                     /* todo_flags_finish */
+ }
+};
+
+
+/* -------------------------------------------------------------------------
+   Fast DCE functions
+   ------------------------------------------------------------------------- */
+
+/* Process basic block BB.  Return true if the live_in set has
+   changed. REDO_OUT is true if the info at the bottom of the block
+   needs to be recalculated before starting.  AU is the proper set of
+   artificial uses. */
+
+static bool
+byte_dce_process_block (basic_block bb, bool redo_out, bitmap au)
+{
+  bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack);
+  rtx insn;
+  bool block_changed;
+  df_ref *def_rec;
+
+  if (redo_out)
+    {
+      /* Need to redo the live_out set of this block if when one of
+	 the succs of this block has had a change in it live in
+	 set.  */
+      edge e;
+      edge_iterator ei;
+      df_confluence_function_n con_fun_n = df_byte_lr->problem->con_fun_n;
+      bitmap_clear (DF_BYTE_LR_OUT (bb));
+      FOR_EACH_EDGE (e, ei, bb->succs)
+	(*con_fun_n) (e);
+    }
+
+  if (dump_file)
+    {
+      fprintf (dump_file, "processing block %d live out = ", bb->index);
+      df_print_byte_regset (dump_file, DF_BYTE_LR_OUT (bb));
+    }
+
+  bitmap_copy (local_live, DF_BYTE_LR_OUT (bb));
+
+  df_byte_lr_simulate_artificial_refs_at_end (bb, local_live);
+
+  FOR_BB_INSNS_REVERSE (bb, insn)
+    if (INSN_P (insn))
+      {
+	/* The insn is needed if there is someone who uses the output.  */
+	for (def_rec = DF_INSN_DEFS (insn); *def_rec; def_rec++)
+	  {
+	    df_ref def = *def_rec;
+	    unsigned int last;
+	    unsigned int dregno = DF_REF_REGNO (def);
+	    unsigned int start = df_byte_lr_get_regno_start (dregno);
+	    unsigned int len = df_byte_lr_get_regno_len (dregno);
+
+	    unsigned int sb;
+	    unsigned int lb;
+	    /* This is one of the only places where DF_MM_MAY should
+	       be used for defs.  Need to make sure that we are
+	       checking for all of the bits that may be used.  */
+
+	    if (!df_compute_accessed_bytes (def, DF_MM_MAY, &sb, &lb))
+	      {
+		start += sb;
+		len = lb - sb;
+	      }
+
+	    if (bitmap_bit_p (au, dregno))
+	      {
+		mark_insn (insn, true);
+		goto quickexit;
+	      }
+	    
+	    last = start + len;
+	    while (start < last)
+	      if (bitmap_bit_p (local_live, start++))
+		{
+		  mark_insn (insn, true);
+		  goto quickexit;
+		}
+	  }
+	
+      quickexit: 
+	
+	/* No matter if the instruction is needed or not, we remove
+	   any regno in the defs from the live set.  */
+	df_byte_lr_simulate_defs (insn, local_live);
+
+	/* On the other hand, we do not allow the dead uses to set
+	   anything in local_live.  */
+	if (marked_insn_p (insn))
+	  df_byte_lr_simulate_uses (insn, local_live);
+
+	if (dump_file)
+	  {
+	    fprintf (dump_file, "finished processing insn %d live out = ", 
+		     INSN_UID (insn));
+	    df_print_byte_regset (dump_file, local_live);
+	  }
+      }
+  
+  df_byte_lr_simulate_artificial_refs_at_top (bb, local_live);
+
+  block_changed = !bitmap_equal_p (local_live, DF_BYTE_LR_IN (bb));
+  if (block_changed)
+    bitmap_copy (DF_BYTE_LR_IN (bb), local_live);
+  BITMAP_FREE (local_live);
+  return block_changed;
+}
+
+
+/* Process basic block BB.  Return true if the live_in set has
+   changed. REDO_OUT is true if the info at the bottom of the block
+   needs to be recalculated before starting.  AU is the proper set of
+   artificial uses. */
+
+static bool
+dce_process_block (basic_block bb, bool redo_out, bitmap au)
+{
+  bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack);
+  rtx insn;
+  bool block_changed;
+  df_ref *def_rec;
+
+  if (redo_out)
+    {
+      /* Need to redo the live_out set of this block if when one of
+	 the succs of this block has had a change in it live in
+	 set.  */
+      edge e;
+      edge_iterator ei;
+      df_confluence_function_n con_fun_n = df_lr->problem->con_fun_n;
+      bitmap_clear (DF_LR_OUT (bb));
+      FOR_EACH_EDGE (e, ei, bb->succs)
+	(*con_fun_n) (e);
+    }
+
+  if (dump_file)
+    {
+      fprintf (dump_file, "processing block %d lr out = ", bb->index);
+      df_print_regset (dump_file, DF_LR_OUT (bb));
+    }
+
+  bitmap_copy (local_live, DF_LR_OUT (bb));
+
+  df_simulate_initialize_backwards (bb, local_live);
+
+  FOR_BB_INSNS_REVERSE (bb, insn)
+    if (INSN_P (insn))
+      {
+	bool needed = false;
+
+	/* The insn is needed if there is someone who uses the output.  */
+	for (def_rec = DF_INSN_DEFS (insn); *def_rec; def_rec++)
+	  if (bitmap_bit_p (local_live, DF_REF_REGNO (*def_rec))
+	      || bitmap_bit_p (au, DF_REF_REGNO (*def_rec)))
+	    {
+	      needed = true;
+	      break;
+	    }
+	    
+	if (needed)
+	  mark_insn (insn, true);
+	
+	/* No matter if the instruction is needed or not, we remove
+	   any regno in the defs from the live set.  */
+	df_simulate_defs (insn, local_live);
+
+	/* On the other hand, we do not allow the dead uses to set
+	   anything in local_live.  */
+	if (marked_insn_p (insn))
+	  df_simulate_uses (insn, local_live);
+      }
+  
+  df_simulate_finalize_backwards (bb, local_live);
+
+  block_changed = !bitmap_equal_p (local_live, DF_LR_IN (bb));
+  if (block_changed)
+    bitmap_copy (DF_LR_IN (bb), local_live);
+
+  BITMAP_FREE (local_live);
+  return block_changed;
+}
+
+
+/* Perform fast DCE once initialization is done.  If BYTE_LEVEL is
+   true, use the byte level dce, otherwise do it at the pseudo
+   level.  */
+
+static void
+fast_dce (bool byte_level)
+{
+  int *postorder = df_get_postorder (DF_BACKWARD);
+  int n_blocks = df_get_n_blocks (DF_BACKWARD);
+  /* The set of blocks that have been seen on this iteration.  */
+  bitmap processed = BITMAP_ALLOC (&dce_blocks_bitmap_obstack);
+  /* The set of blocks that need to have the out vectors reset because
+     the in of one of their successors has changed.  */
+  bitmap redo_out = BITMAP_ALLOC (&dce_blocks_bitmap_obstack);
+  bitmap all_blocks = BITMAP_ALLOC (&dce_blocks_bitmap_obstack);
+  bool global_changed = true;
+
+  /* These regs are considered always live so if they end up dying
+     because of some def, we need to bring the back again.  Calling
+     df_simulate_fixup_sets has the disadvantage of calling
+     bb_has_eh_pred once per insn, so we cache the information
+     here.  */
+  bitmap au = df->regular_block_artificial_uses;
+  bitmap au_eh = df->eh_block_artificial_uses;
+  int i;
+
+  prescan_insns_for_dce (true);
+
+  for (i = 0; i < n_blocks; i++)
+    bitmap_set_bit (all_blocks, postorder[i]);
+
+  while (global_changed)
+    {
+      global_changed = false;
+
+      for (i = 0; i < n_blocks; i++)
+	{
+	  int index = postorder[i];
+	  basic_block bb = BASIC_BLOCK (index);
+	  bool local_changed;
+
+	  if (index < NUM_FIXED_BLOCKS)
+	    {
+	      bitmap_set_bit (processed, index);
+	      continue;
+	    }
+
+	  if (byte_level)
+	    local_changed 
+	      = byte_dce_process_block (bb, bitmap_bit_p (redo_out, index),
+					  bb_has_eh_pred (bb) ? au_eh : au);
+	  else
+	    local_changed 
+	      = dce_process_block (bb, bitmap_bit_p (redo_out, index),
+				   bb_has_eh_pred (bb) ? au_eh : au);
+	  bitmap_set_bit (processed, index);
+	  
+	  if (local_changed)
+	    {
+	      edge e;
+	      edge_iterator ei;
+	      FOR_EACH_EDGE (e, ei, bb->preds)
+		if (bitmap_bit_p (processed, e->src->index))
+		  /* Be tricky about when we need to iterate the
+		     analysis.  We only have redo the analysis if the
+		     bitmaps change at the top of a block that is the
+		     entry to a loop.  */
+		  global_changed = true;
+		else
+		  bitmap_set_bit (redo_out, e->src->index);
+	    }
+	}
+      
+      if (global_changed)
+	{
+	  /* Turn off the RUN_DCE flag to prevent recursive calls to
+	     dce.  */
+	  int old_flag = df_clear_flags (DF_LR_RUN_DCE);
+
+	  /* So something was deleted that requires a redo.  Do it on
+	     the cheap.  */
+	  delete_unmarked_insns ();
+	  sbitmap_zero (marked);
+	  bitmap_clear (processed);
+	  bitmap_clear (redo_out);
+	  
+	  /* We do not need to rescan any instructions.  We only need
+	     to redo the dataflow equations for the blocks that had a
+	     change at the top of the block.  Then we need to redo the
+	     iteration.  */ 
+	  if (byte_level)
+	    df_analyze_problem (df_byte_lr, all_blocks, postorder, n_blocks);
+	  else
+	    df_analyze_problem (df_lr, all_blocks, postorder, n_blocks);
+
+	  if (old_flag & DF_LR_RUN_DCE)
+	    df_set_flags (DF_LR_RUN_DCE);
+
+	  prescan_insns_for_dce (true);
+	}
+    }
+
+  delete_unmarked_insns ();
+
+  BITMAP_FREE (processed);
+  BITMAP_FREE (redo_out);
+  BITMAP_FREE (all_blocks);
+}
+
+
+/* Fast register level DCE.  */
+
+static unsigned int
+rest_of_handle_fast_dce (void)
+{
+  init_dce (true);
+  fast_dce (false);
+  fini_dce (true);
+  return 0;
+}
+
+
+/* Fast byte level DCE.  */
+
+static unsigned int
+rest_of_handle_fast_byte_dce (void)
+{
+  df_byte_lr_add_problem ();
+  init_dce (true);
+  fast_dce (true);
+  fini_dce (true);
+  return 0;
+}
+
+
+/* This is an internal call that is used by the df live register
+   problem to run fast dce as a side effect of creating the live
+   information.  The stack is organized so that the lr problem is run,
+   this pass is run, which updates the live info and the df scanning
+   info, and then returns to allow the rest of the problems to be run.
+
+   This can be called by elsewhere but it will not update the bit
+   vectors for any other problems than LR.  */
+
+void
+run_fast_df_dce (void)
+{
+  if (flag_dce)
+    {
+      /* If dce is able to delete something, it has to happen
+	 immediately.  Otherwise there will be problems handling the
+	 eq_notes.  */
+      enum df_changeable_flags old_flags 
+	= df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN);
+      
+      df_in_progress = true;
+      rest_of_handle_fast_dce ();
+      df_in_progress = false;
+
+      df_set_flags (old_flags);
+    }
+}
+
+
+/* Run a fast DCE pass.  */
+
+void
+run_fast_dce (void)
+{
+  if (flag_dce)
+    rest_of_handle_fast_dce ();
+}
+
+
+static bool
+gate_fast_dce (void)
+{
+  return optimize > 0 && flag_dce
+    && dbg_cnt (dce_fast);
+}
+
+struct rtl_opt_pass pass_fast_rtl_dce =
+{
+ {
+  RTL_PASS,
+  "dce",                                /* name */
+  gate_fast_dce,                        /* gate */
+  rest_of_handle_fast_dce,              /* execute */
+  NULL,                                 /* sub */
+  NULL,                                 /* next */
+  0,                                    /* static_pass_number */
+  TV_DCE,                               /* tv_id */
+  0,                                    /* properties_required */
+  0,                                    /* properties_provided */
+  0,                                    /* properties_destroyed */
+  0,                                    /* todo_flags_start */
+  TODO_dump_func |
+  TODO_df_finish | TODO_verify_rtl_sharing |
+  TODO_ggc_collect                      /* todo_flags_finish */
+ }
+};
+
+struct rtl_opt_pass pass_fast_rtl_byte_dce =
+{
+ {
+  RTL_PASS,
+  "byte-dce",                           /* name */
+  gate_fast_dce,                        /* gate */
+  rest_of_handle_fast_byte_dce,         /* execute */
+  NULL,                                 /* sub */
+  NULL,                                 /* next */
+  0,                                    /* static_pass_number */
+  TV_DCE,                               /* tv_id */
+  0,                                    /* properties_required */
+  0,                                    /* properties_provided */
+  0,                                    /* properties_destroyed */
+  0,                                    /* todo_flags_start */
+  TODO_dump_func |
+  TODO_df_finish | TODO_verify_rtl_sharing |
+  TODO_ggc_collect                      /* todo_flags_finish */
+ }
+};