--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/tree-ssa-operands.c	Fri Jul 17 14:47:48 2009 +0900
@@ -0,0 +1,2738 @@
+/* SSA operands management for trees.
+   Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008
+   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 "tm.h"
+#include "tree.h"
+#include "flags.h"
+#include "function.h"
+#include "diagnostic.h"
+#include "tree-flow.h"
+#include "tree-inline.h"
+#include "tree-pass.h"
+#include "ggc.h"
+#include "timevar.h"
+#include "toplev.h"
+#include "langhooks.h"
+#include "ipa-reference.h"
+
+/* This file contains the code required to manage the operands cache of the 
+   SSA optimizer.  For every stmt, we maintain an operand cache in the stmt 
+   annotation.  This cache contains operands that will be of interest to 
+   optimizers and other passes wishing to manipulate the IL. 
+
+   The operand type are broken up into REAL and VIRTUAL operands.  The real 
+   operands are represented as pointers into the stmt's operand tree.  Thus 
+   any manipulation of the real operands will be reflected in the actual tree.
+   Virtual operands are represented solely in the cache, although the base 
+   variable for the SSA_NAME may, or may not occur in the stmt's tree.  
+   Manipulation of the virtual operands will not be reflected in the stmt tree.
+
+   The routines in this file are concerned with creating this operand cache 
+   from a stmt tree.
+
+   The operand tree is the parsed by the various get_* routines which look 
+   through the stmt tree for the occurrence of operands which may be of 
+   interest, and calls are made to the append_* routines whenever one is 
+   found.  There are 4 of these routines, each representing one of the 
+   4 types of operands. Defs, Uses, Virtual Uses, and Virtual May Defs.
+
+   The append_* routines check for duplication, and simply keep a list of 
+   unique objects for each operand type in the build_* extendable vectors.
+
+   Once the stmt tree is completely parsed, the finalize_ssa_operands() 
+   routine is called, which proceeds to perform the finalization routine 
+   on each of the 4 operand vectors which have been built up.
+
+   If the stmt had a previous operand cache, the finalization routines 
+   attempt to match up the new operands with the old ones.  If it's a perfect 
+   match, the old vector is simply reused.  If it isn't a perfect match, then 
+   a new vector is created and the new operands are placed there.  For 
+   virtual operands, if the previous cache had SSA_NAME version of a 
+   variable, and that same variable occurs in the same operands cache, then 
+   the new cache vector will also get the same SSA_NAME.
+
+   i.e., if a stmt had a VUSE of 'a_5', and 'a' occurs in the new
+   operand vector for VUSE, then the new vector will also be modified
+   such that it contains 'a_5' rather than 'a'.  */
+
+/* Helper functions from gimple.c.  These are GIMPLE manipulation
+   routines that only the operand scanner should need.  */
+void gimple_set_stored_syms (gimple, bitmap, bitmap_obstack *);
+void gimple_set_loaded_syms (gimple, bitmap, bitmap_obstack *);
+
+/* Structure storing statistics on how many call clobbers we have, and
+   how many where avoided.  */
+
+static struct 
+{
+  /* Number of call-clobbered ops we attempt to add to calls in
+     add_call_clobbered_mem_symbols.  */
+  unsigned int clobbered_vars;
+
+  /* Number of write-clobbers (VDEFs) avoided by using
+     not_written information.  */
+  unsigned int static_write_clobbers_avoided;
+
+  /* Number of reads (VUSEs) avoided by using not_read information.  */
+  unsigned int static_read_clobbers_avoided;
+  
+  /* Number of write-clobbers avoided because the variable can't escape to
+     this call.  */
+  unsigned int unescapable_clobbers_avoided;
+
+  /* Number of read-only uses we attempt to add to calls in
+     add_call_read_mem_symbols.  */
+  unsigned int readonly_clobbers;
+
+  /* Number of read-only uses we avoid using not_read information.  */
+  unsigned int static_readonly_clobbers_avoided;
+} clobber_stats;
+
+
+/* Flags to describe operand properties in helpers.  */
+
+/* By default, operands are loaded.  */
+#define opf_use		0
+
+/* Operand is the target of an assignment expression or a 
+   call-clobbered variable.  */
+#define opf_def 	(1 << 0)
+
+/* No virtual operands should be created in the expression.  This is used
+   when traversing ADDR_EXPR nodes which have different semantics than
+   other expressions.  Inside an ADDR_EXPR node, the only operands that we
+   need to consider are indices into arrays.  For instance, &a.b[i] should
+   generate a USE of 'i' but it should not generate a VUSE for 'a' nor a
+   VUSE for 'b'.  */
+#define opf_no_vops 	(1 << 1)
+
+/* Operand is an implicit reference.  This is used to distinguish
+   explicit assignments in the form of MODIFY_EXPR from
+   clobbering sites like function calls or ASM_EXPRs.  */
+#define opf_implicit	(1 << 2)
+
+/* Array for building all the def operands.  */
+static VEC(tree,heap) *build_defs;
+
+/* Array for building all the use operands.  */
+static VEC(tree,heap) *build_uses;
+
+/* Set for building all the VDEF operands.  */
+static VEC(tree,heap) *build_vdefs;
+
+/* Set for building all the VUSE operands.  */
+static VEC(tree,heap) *build_vuses;
+
+/* Bitmap obstack for our datastructures that needs to survive across	
+   compilations of multiple functions.  */
+static bitmap_obstack operands_bitmap_obstack;
+
+/* Set for building all the loaded symbols.  */
+static bitmap build_loads;
+
+/* Set for building all the stored symbols.  */
+static bitmap build_stores;
+
+static void get_expr_operands (gimple, tree *, int);
+
+/* Number of functions with initialized ssa_operands.  */
+static int n_initialized = 0;
+
+/* Statement change buffer.  Data structure used to record state
+   information for statements.  This is used to determine what needs
+   to be done in order to update the SSA web after a statement is
+   modified by a pass.  If STMT is a statement that has just been
+   created, or needs to be folded via fold_stmt, or anything that
+   changes its physical structure then the pass should:
+
+   1- Call push_stmt_changes (&stmt) to record the current state of
+      STMT before any modifications are made.
+
+   2- Make all appropriate modifications to the statement.
+
+   3- Call pop_stmt_changes (&stmt) to find new symbols that
+      need to be put in SSA form, SSA name mappings for names that
+      have disappeared, recompute invariantness for address
+      expressions, cleanup EH information, etc.
+
+   If it is possible to determine that the statement was not modified,
+   instead of calling pop_stmt_changes it is quicker to call
+   discard_stmt_changes to avoid the expensive and unnecessary operand
+   re-scan and change comparison.  */
+
+struct scb_d
+{
+  /* Pointer to the statement being modified.  */
+  gimple *stmt_p;
+
+  /* If the statement references memory these are the sets of symbols
+     loaded and stored by the statement.  */
+  bitmap loads;
+  bitmap stores;
+};
+
+typedef struct scb_d *scb_t;
+DEF_VEC_P(scb_t);
+DEF_VEC_ALLOC_P(scb_t,heap);
+
+/* Stack of statement change buffers (SCB).  Every call to
+   push_stmt_changes pushes a new buffer onto the stack.  Calls to
+   pop_stmt_changes pop a buffer off of the stack and compute the set
+   of changes for the popped statement.  */
+static VEC(scb_t,heap) *scb_stack;
+
+/* Return the DECL_UID of the base variable of T.  */
+
+static inline unsigned
+get_name_decl (const_tree t)
+{
+  if (TREE_CODE (t) != SSA_NAME)
+    return DECL_UID (t);
+  else
+    return DECL_UID (SSA_NAME_VAR (t));
+}
+
+
+/* Comparison function for qsort used in operand_build_sort_virtual.  */
+
+int
+operand_build_cmp (const void *p, const void *q)
+{
+  const_tree const e1 = *((const_tree const *)p);
+  const_tree const e2 = *((const_tree const *)q);
+  const unsigned int u1 = get_name_decl (e1);
+  const unsigned int u2 = get_name_decl (e2);
+
+  /* We want to sort in ascending order.  They can never be equal.  */
+#ifdef ENABLE_CHECKING
+  gcc_assert (u1 != u2);
+#endif
+  return (u1 > u2 ? 1 : -1);
+}
+
+
+/* Sort the virtual operands in LIST from lowest DECL_UID to highest.  */
+
+static inline void
+operand_build_sort_virtual (VEC(tree,heap) *list)
+{
+  int num = VEC_length (tree, list);
+
+  if (num < 2)
+    return;
+
+  if (num == 2)
+    {
+      if (get_name_decl (VEC_index (tree, list, 0)) 
+	  > get_name_decl (VEC_index (tree, list, 1)))
+	{  
+	  /* Swap elements if in the wrong order.  */
+	  tree tmp = VEC_index (tree, list, 0);
+	  VEC_replace (tree, list, 0, VEC_index (tree, list, 1));
+	  VEC_replace (tree, list, 1, tmp);
+	}
+      return;
+    }
+
+  /* There are 3 or more elements, call qsort.  */
+  qsort (VEC_address (tree, list), 
+	 VEC_length (tree, list), 
+	 sizeof (tree),
+	 operand_build_cmp);
+}
+
+/*  Return true if the SSA operands cache is active.  */
+
+bool
+ssa_operands_active (void)
+{
+  /* This function may be invoked from contexts where CFUN is NULL
+     (IPA passes), return false for now.  FIXME: operands may be
+     active in each individual function, maybe this function should
+     take CFUN as a parameter.  */
+  if (cfun == NULL)
+    return false;
+
+  return cfun->gimple_df && gimple_ssa_operands (cfun)->ops_active;
+}
+
+
+/* VOPs are of variable sized, so the free list maps "free buckets" to the 
+   following table:  
+    bucket   # operands
+    ------   ----------
+	0	1
+	1	2
+	  ...
+	15	16
+	16	17-24
+	17	25-32
+	18	31-40
+	  ...
+	29	121-128
+   Any VOPs larger than this are simply added to the largest bucket when they
+   are freed.  */
+
+
+/* Return the number of operands used in bucket BUCKET.  */
+
+static inline int
+vop_free_bucket_size (int bucket)
+{
+#ifdef ENABLE_CHECKING
+  gcc_assert (bucket >= 0 && bucket < NUM_VOP_FREE_BUCKETS);
+#endif
+  if (bucket < 16)
+    return bucket + 1;
+  return (bucket - 13) * 8;
+}
+
+
+/* For a vop of NUM operands, return the bucket NUM belongs to.  If NUM is 
+   beyond the end of the bucket table, return -1.  */
+
+static inline int 
+vop_free_bucket_index (int num)
+{
+  gcc_assert (num > 0 && NUM_VOP_FREE_BUCKETS > 16);
+
+  /* Sizes 1 through 16 use buckets 0-15.  */
+  if (num <= 16)
+    return num - 1;
+  /* Buckets 16 - NUM_VOP_FREE_BUCKETS represent 8 unit chunks.  */
+  num = 14 + (num - 1) / 8;
+  if (num >= NUM_VOP_FREE_BUCKETS)
+    return -1;
+  else
+    return num;
+}
+
+
+/* Initialize the VOP free buckets.  */
+
+static inline void
+init_vop_buckets (void)
+{
+  int x;
+
+  for (x = 0; x < NUM_VOP_FREE_BUCKETS; x++)
+    gimple_ssa_operands (cfun)->vop_free_buckets[x] = NULL;
+}
+
+
+/* Add PTR to the appropriate VOP bucket.  */
+
+static inline void
+add_vop_to_freelist (voptype_p ptr)
+{
+  int bucket = vop_free_bucket_index (VUSE_VECT_NUM_ELEM (ptr->usev));
+
+  /* Too large, use the largest bucket so its not a complete throw away.  */
+  if (bucket == -1)
+    bucket = NUM_VOP_FREE_BUCKETS - 1;
+
+  ptr->next = gimple_ssa_operands (cfun)->vop_free_buckets[bucket];
+  gimple_ssa_operands (cfun)->vop_free_buckets[bucket] = ptr;
+}
+ 
+
+/* These are the sizes of the operand memory  buffer which gets allocated each 
+   time more operands space is required.  The final value is the amount that is
+   allocated every time after that.  */
+  
+#define OP_SIZE_INIT	0
+#define OP_SIZE_1	30
+#define OP_SIZE_2	110
+#define OP_SIZE_3	511
+
+/* Initialize the operand cache routines.  */
+
+void
+init_ssa_operands (void)
+{
+  if (!n_initialized++)
+    {
+      build_defs = VEC_alloc (tree, heap, 5);
+      build_uses = VEC_alloc (tree, heap, 10);
+      build_vuses = VEC_alloc (tree, heap, 25);
+      build_vdefs = VEC_alloc (tree, heap, 25);
+      bitmap_obstack_initialize (&operands_bitmap_obstack);
+      build_loads = BITMAP_ALLOC (&operands_bitmap_obstack);
+      build_stores = BITMAP_ALLOC (&operands_bitmap_obstack);
+      scb_stack = VEC_alloc (scb_t, heap, 20);
+    }
+
+  gcc_assert (gimple_ssa_operands (cfun)->operand_memory == NULL);
+  gcc_assert (gimple_ssa_operands (cfun)->mpt_table == NULL);
+  gimple_ssa_operands (cfun)->operand_memory_index
+     = gimple_ssa_operands (cfun)->ssa_operand_mem_size;
+  gimple_ssa_operands (cfun)->ops_active = true;
+  memset (&clobber_stats, 0, sizeof (clobber_stats));
+  init_vop_buckets ();
+  gimple_ssa_operands (cfun)->ssa_operand_mem_size = OP_SIZE_INIT;
+}
+
+
+/* Dispose of anything required by the operand routines.  */
+
+void
+fini_ssa_operands (void)
+{
+  struct ssa_operand_memory_d *ptr;
+  unsigned ix;
+  tree mpt;
+
+  if (!--n_initialized)
+    {
+      VEC_free (tree, heap, build_defs);
+      VEC_free (tree, heap, build_uses);
+      VEC_free (tree, heap, build_vdefs);
+      VEC_free (tree, heap, build_vuses);
+      BITMAP_FREE (build_loads);
+      BITMAP_FREE (build_stores);
+
+      /* The change buffer stack had better be empty.  */
+      gcc_assert (VEC_length (scb_t, scb_stack) == 0);
+      VEC_free (scb_t, heap, scb_stack);
+      scb_stack = NULL;
+    }
+
+  gimple_ssa_operands (cfun)->free_defs = NULL;
+  gimple_ssa_operands (cfun)->free_uses = NULL;
+
+  while ((ptr = gimple_ssa_operands (cfun)->operand_memory) != NULL)
+    {
+      gimple_ssa_operands (cfun)->operand_memory
+	= gimple_ssa_operands (cfun)->operand_memory->next;
+      ggc_free (ptr);
+    }
+
+  for (ix = 0;
+       VEC_iterate (tree, gimple_ssa_operands (cfun)->mpt_table, ix, mpt);
+       ix++)
+    {
+      if (mpt)
+	BITMAP_FREE (MPT_SYMBOLS (mpt));
+    }
+
+  VEC_free (tree, heap, gimple_ssa_operands (cfun)->mpt_table);
+
+  gimple_ssa_operands (cfun)->ops_active = false;
+
+  if (!n_initialized)
+    bitmap_obstack_release (&operands_bitmap_obstack);
+
+  if (dump_file && (dump_flags & TDF_STATS))
+    {
+      fprintf (dump_file, "Original clobbered vars:           %d\n",
+	       clobber_stats.clobbered_vars);
+      fprintf (dump_file, "Static write clobbers avoided:     %d\n",
+	       clobber_stats.static_write_clobbers_avoided);
+      fprintf (dump_file, "Static read clobbers avoided:      %d\n",
+	       clobber_stats.static_read_clobbers_avoided);
+      fprintf (dump_file, "Unescapable clobbers avoided:      %d\n",
+	       clobber_stats.unescapable_clobbers_avoided);
+      fprintf (dump_file, "Original read-only clobbers:       %d\n",
+	       clobber_stats.readonly_clobbers);
+      fprintf (dump_file, "Static read-only clobbers avoided: %d\n",
+	       clobber_stats.static_readonly_clobbers_avoided);
+    }
+}
+
+
+/* Return memory for operands of SIZE chunks.  */
+                                                                              
+static inline void *
+ssa_operand_alloc (unsigned size)
+{
+  char *ptr;
+
+  if (gimple_ssa_operands (cfun)->operand_memory_index + size
+      >= gimple_ssa_operands (cfun)->ssa_operand_mem_size)
+    {
+      struct ssa_operand_memory_d *ptr;
+
+      if (gimple_ssa_operands (cfun)->ssa_operand_mem_size == OP_SIZE_INIT)
+	gimple_ssa_operands (cfun)->ssa_operand_mem_size
+	   = OP_SIZE_1 * sizeof (struct voptype_d);
+      else
+	if (gimple_ssa_operands (cfun)->ssa_operand_mem_size
+	    == OP_SIZE_1 * sizeof (struct voptype_d))
+	  gimple_ssa_operands (cfun)->ssa_operand_mem_size
+	     = OP_SIZE_2 * sizeof (struct voptype_d);
+	else
+	  gimple_ssa_operands (cfun)->ssa_operand_mem_size
+	     = OP_SIZE_3 * sizeof (struct voptype_d);
+
+      /* Go right to the maximum size if the request is too large.  */
+      if (size > gimple_ssa_operands (cfun)->ssa_operand_mem_size)
+        gimple_ssa_operands (cfun)->ssa_operand_mem_size
+	  = OP_SIZE_3 * sizeof (struct voptype_d);
+
+      /* We can reliably trigger the case that we need arbitrary many
+	 operands (see PR34093), so allocate a buffer just for this request.  */
+      if (size > gimple_ssa_operands (cfun)->ssa_operand_mem_size)
+	gimple_ssa_operands (cfun)->ssa_operand_mem_size = size;
+
+      ptr = (struct ssa_operand_memory_d *) 
+	      ggc_alloc (sizeof (struct ssa_operand_memory_d) 
+			 + gimple_ssa_operands (cfun)->ssa_operand_mem_size - 1);
+      ptr->next = gimple_ssa_operands (cfun)->operand_memory;
+      gimple_ssa_operands (cfun)->operand_memory = ptr;
+      gimple_ssa_operands (cfun)->operand_memory_index = 0;
+    }
+  ptr = &(gimple_ssa_operands (cfun)->operand_memory
+	  ->mem[gimple_ssa_operands (cfun)->operand_memory_index]);
+  gimple_ssa_operands (cfun)->operand_memory_index += size;
+  return ptr;
+}
+
+
+/* Allocate a DEF operand.  */
+
+static inline struct def_optype_d *
+alloc_def (void)
+{
+  struct def_optype_d *ret;
+  if (gimple_ssa_operands (cfun)->free_defs)
+    {
+      ret = gimple_ssa_operands (cfun)->free_defs;
+      gimple_ssa_operands (cfun)->free_defs
+	= gimple_ssa_operands (cfun)->free_defs->next;
+    }
+  else
+    ret = (struct def_optype_d *)
+	  ssa_operand_alloc (sizeof (struct def_optype_d));
+  return ret;
+}
+
+
+/* Allocate a USE operand.  */
+
+static inline struct use_optype_d *
+alloc_use (void)
+{
+  struct use_optype_d *ret;
+  if (gimple_ssa_operands (cfun)->free_uses)
+    {
+      ret = gimple_ssa_operands (cfun)->free_uses;
+      gimple_ssa_operands (cfun)->free_uses
+	= gimple_ssa_operands (cfun)->free_uses->next;
+    }
+  else
+    ret = (struct use_optype_d *)
+          ssa_operand_alloc (sizeof (struct use_optype_d));
+  return ret;
+}
+
+
+/* Allocate a vop with NUM elements.  */
+
+static inline struct voptype_d *
+alloc_vop (int num)
+{
+  struct voptype_d *ret = NULL;
+  int alloc_size = 0;
+
+  int bucket = vop_free_bucket_index (num);
+  if (bucket != -1)
+    {
+      /* If there is a free operand, use it.  */
+      if (gimple_ssa_operands (cfun)->vop_free_buckets[bucket] != NULL)
+	{
+	  ret = gimple_ssa_operands (cfun)->vop_free_buckets[bucket];
+	  gimple_ssa_operands (cfun)->vop_free_buckets[bucket] = 
+		  gimple_ssa_operands (cfun)->vop_free_buckets[bucket]->next;
+	}
+      else
+        alloc_size = vop_free_bucket_size(bucket);
+    }
+  else
+    alloc_size = num;
+
+  if (alloc_size > 0)
+    ret = (struct voptype_d *)ssa_operand_alloc (
+	sizeof (struct voptype_d) + (alloc_size - 1) * sizeof (vuse_element_t));
+
+  VUSE_VECT_NUM_ELEM (ret->usev) = num;
+  return ret;
+}
+
+
+/* This routine makes sure that PTR is in an immediate use list, and makes
+   sure the stmt pointer is set to the current stmt.  */
+
+static inline void
+set_virtual_use_link (use_operand_p ptr, gimple stmt)
+{
+  /*  fold_stmt may have changed the stmt pointers.  */
+  if (ptr->loc.stmt != stmt)
+    ptr->loc.stmt = stmt;
+
+  /* If this use isn't in a list, add it to the correct list.  */
+  if (!ptr->prev)
+    link_imm_use (ptr, *(ptr->use));
+}
+
+
+/* Adds OP to the list of defs after LAST.  */
+
+static inline def_optype_p 
+add_def_op (tree *op, def_optype_p last)
+{
+  def_optype_p new_def;
+
+  new_def = alloc_def ();
+  DEF_OP_PTR (new_def) = op;
+  last->next = new_def;
+  new_def->next = NULL;
+  return new_def;
+}
+
+
+/* Adds OP to the list of uses of statement STMT after LAST.  */
+
+static inline use_optype_p
+add_use_op (gimple stmt, tree *op, use_optype_p last)
+{
+  use_optype_p new_use;
+
+  new_use = alloc_use ();
+  USE_OP_PTR (new_use)->use = op;
+  link_imm_use_stmt (USE_OP_PTR (new_use), *op, stmt);
+  last->next = new_use;
+  new_use->next = NULL;
+  return new_use;
+}
+
+
+/* Return a virtual op pointer with NUM elements which are all
+   initialized to OP and are linked into the immediate uses for STMT.
+   The new vop is appended after PREV.  */
+
+static inline voptype_p
+add_vop (gimple stmt, tree op, int num, voptype_p prev)
+{
+  voptype_p new_vop;
+  int x;
+
+  new_vop = alloc_vop (num);
+  for (x = 0; x < num; x++)
+    {
+      VUSE_OP_PTR (new_vop, x)->prev = NULL;
+      SET_VUSE_OP (new_vop, x, op);
+      VUSE_OP_PTR (new_vop, x)->use = &new_vop->usev.uses[x].use_var;
+      link_imm_use_stmt (VUSE_OP_PTR (new_vop, x),
+			 new_vop->usev.uses[x].use_var, stmt);
+    }
+
+  if (prev)
+    prev->next = new_vop;
+  new_vop->next = NULL;
+  return new_vop;
+}
+
+
+/* Adds OP to the list of vuses of statement STMT after LAST, and moves
+   LAST to the new element.  */
+
+static inline voptype_p
+add_vuse_op (gimple stmt, tree op, int num, voptype_p last)
+{
+  voptype_p new_vop = add_vop (stmt, op, num, last);
+  VDEF_RESULT (new_vop) = NULL_TREE;
+  return new_vop;
+}
+
+
+/* Adds OP to the list of vdefs of statement STMT after LAST, and moves
+   LAST to the new element.  */
+
+static inline voptype_p
+add_vdef_op (gimple stmt, tree op, int num, voptype_p last)
+{
+  voptype_p new_vop = add_vop (stmt, op, num, last);
+  VDEF_RESULT (new_vop) = op;
+  return new_vop;
+}
+  
+
+/* Takes elements from build_defs and turns them into def operands of STMT.
+   TODO -- Make build_defs VEC of tree *.  */
+
+static inline void
+finalize_ssa_defs (gimple stmt)
+{
+  unsigned new_i;
+  struct def_optype_d new_list;
+  def_optype_p old_ops, last;
+  unsigned int num = VEC_length (tree, build_defs);
+
+  /* There should only be a single real definition per assignment.  */
+  gcc_assert ((stmt && gimple_code (stmt) != GIMPLE_ASSIGN) || num <= 1);
+
+  new_list.next = NULL;
+  last = &new_list;
+
+  old_ops = gimple_def_ops (stmt);
+
+  new_i = 0;
+
+  /* Check for the common case of 1 def that hasn't changed.  */
+  if (old_ops && old_ops->next == NULL && num == 1
+      && (tree *) VEC_index (tree, build_defs, 0) == DEF_OP_PTR (old_ops))
+    return;
+
+  /* If there is anything in the old list, free it.  */
+  if (old_ops)
+    {
+      old_ops->next = gimple_ssa_operands (cfun)->free_defs;
+      gimple_ssa_operands (cfun)->free_defs = old_ops;
+    }
+
+  /* If there is anything remaining in the build_defs list, simply emit it.  */
+  for ( ; new_i < num; new_i++)
+    last = add_def_op ((tree *) VEC_index (tree, build_defs, new_i), last);
+
+  /* Now set the stmt's operands.  */
+  gimple_set_def_ops (stmt, new_list.next);
+
+#ifdef ENABLE_CHECKING
+  {
+    def_optype_p ptr;
+    unsigned x = 0;
+    for (ptr = gimple_def_ops (stmt); ptr; ptr = ptr->next)
+      x++;
+
+    gcc_assert (x == num);
+  }
+#endif
+}
+
+
+/* Takes elements from build_uses and turns them into use operands of STMT.
+   TODO -- Make build_uses VEC of tree *.  */
+
+static inline void
+finalize_ssa_uses (gimple stmt)
+{
+  unsigned new_i;
+  struct use_optype_d new_list;
+  use_optype_p old_ops, ptr, last;
+
+  new_list.next = NULL;
+  last = &new_list;
+
+  old_ops = gimple_use_ops (stmt);
+
+  /* If there is anything in the old list, free it.  */
+  if (old_ops)
+    {
+      for (ptr = old_ops; ptr; ptr = ptr->next)
+	delink_imm_use (USE_OP_PTR (ptr));
+      old_ops->next = gimple_ssa_operands (cfun)->free_uses;
+      gimple_ssa_operands (cfun)->free_uses = old_ops;
+    }
+
+  /* Now create nodes for all the new nodes.  */
+  for (new_i = 0; new_i < VEC_length (tree, build_uses); new_i++)
+    last = add_use_op (stmt, 
+		       (tree *) VEC_index (tree, build_uses, new_i), 
+		       last);
+
+  /* Now set the stmt's operands.  */
+  gimple_set_use_ops (stmt, new_list.next);
+
+#ifdef ENABLE_CHECKING
+  {
+    unsigned x = 0;
+    for (ptr = gimple_use_ops (stmt); ptr; ptr = ptr->next)
+      x++;
+
+    gcc_assert (x == VEC_length (tree, build_uses));
+  }
+#endif
+}
+
+
+/* Takes elements from BUILD_VDEFS and turns them into vdef operands of
+   STMT.  */
+
+static inline void
+finalize_ssa_vdefs (gimple stmt)
+{
+  unsigned new_i;
+  struct voptype_d new_list;
+  voptype_p old_ops, ptr, last;
+
+  /* Set the symbols referenced by STMT.  */
+  gimple_set_stored_syms (stmt, build_stores, &operands_bitmap_obstack);
+
+  /* If aliases have not been computed, do not instantiate a virtual
+     operator on STMT.  Initially, we only compute the SSA form on
+     GIMPLE registers.  The virtual SSA form is only computed after
+     alias analysis, so virtual operators will remain unrenamed and
+     the verifier will complain.  However, alias analysis needs to
+     access symbol load/store information, so we need to compute
+     those.  */
+  if (!gimple_aliases_computed_p (cfun))
+    return;
+
+  new_list.next = NULL;
+  last = &new_list;
+
+  old_ops = gimple_vdef_ops (stmt);
+  new_i = 0;
+  while (old_ops && new_i < VEC_length (tree, build_vdefs))
+    {
+      tree op = VEC_index (tree, build_vdefs, new_i);
+      unsigned new_uid = get_name_decl (op);
+      unsigned old_uid = get_name_decl (VDEF_RESULT (old_ops));
+
+      /* FIXME, for now each VDEF operator should have at most one
+	 operand in their RHS.  */
+      gcc_assert (VDEF_NUM (old_ops) == 1);
+
+      if (old_uid == new_uid)
+        {
+	  /* If the symbols are the same, reuse the existing operand.  */
+	  last->next = old_ops;
+	  last = old_ops;
+	  old_ops = old_ops->next;
+	  last->next = NULL;
+	  set_virtual_use_link (VDEF_OP_PTR (last, 0), stmt);
+	  new_i++;
+	}
+      else if (old_uid < new_uid)
+	{
+	  /* If old is less than new, old goes to the free list.  */
+	  voptype_p next;
+	  delink_imm_use (VDEF_OP_PTR (old_ops, 0));
+	  next = old_ops->next;
+	  add_vop_to_freelist (old_ops);
+	  old_ops = next;
+	}
+      else
+	{
+	  /* This is a new operand.  */
+	  last = add_vdef_op (stmt, op, 1, last);
+	  new_i++;
+	}
+    }
+
+  /* If there is anything remaining in BUILD_VDEFS, simply emit it.  */
+  for ( ; new_i < VEC_length (tree, build_vdefs); new_i++)
+    last = add_vdef_op (stmt, VEC_index (tree, build_vdefs, new_i), 1, last);
+
+  /* If there is anything in the old list, free it.  */
+  if (old_ops)
+    {
+      for (ptr = old_ops; ptr; ptr = last)
+        {
+	  last = ptr->next;
+	  delink_imm_use (VDEF_OP_PTR (ptr, 0));
+	  add_vop_to_freelist (ptr);
+	}
+    }
+
+  /* Now set STMT's operands.  */
+  gimple_set_vdef_ops (stmt, new_list.next);
+
+#ifdef ENABLE_CHECKING
+  {
+    unsigned x = 0;
+    for (ptr = gimple_vdef_ops (stmt); ptr; ptr = ptr->next)
+      x++;
+
+    gcc_assert (x == VEC_length (tree, build_vdefs));
+  }
+#endif
+}
+
+
+/* Takes elements from BUILD_VUSES and turns them into VUSE operands of
+   STMT.  */
+
+static inline void
+finalize_ssa_vuse_ops (gimple stmt)
+{
+  unsigned new_i, old_i;
+  voptype_p old_ops, last;
+  VEC(tree,heap) *new_ops;
+
+  /* Set the symbols referenced by STMT.  */
+  gimple_set_loaded_syms (stmt, build_loads, &operands_bitmap_obstack);
+
+  /* If aliases have not been computed, do not instantiate a virtual
+     operator on STMT.  Initially, we only compute the SSA form on
+     GIMPLE registers.  The virtual SSA form is only computed after
+     alias analysis, so virtual operators will remain unrenamed and
+     the verifier will complain.  However, alias analysis needs to
+     access symbol load/store information, so we need to compute
+     those.  */
+  if (!gimple_aliases_computed_p (cfun))
+    return;
+
+  /* STMT should have at most one VUSE operator.  */
+  old_ops = gimple_vuse_ops (stmt);
+  gcc_assert (old_ops == NULL || old_ops->next == NULL);
+
+  new_ops = NULL;
+  new_i = old_i = 0;
+  while (old_ops
+         && old_i < VUSE_NUM (old_ops)
+	 && new_i < VEC_length (tree, build_vuses))
+    {
+      tree new_op = VEC_index (tree, build_vuses, new_i);
+      tree old_op = VUSE_OP (old_ops, old_i);
+      unsigned new_uid = get_name_decl (new_op);
+      unsigned old_uid = get_name_decl (old_op);
+
+      if (old_uid == new_uid)
+        {
+	  /* If the symbols are the same, reuse the existing operand.  */
+	  VEC_safe_push (tree, heap, new_ops, old_op);
+	  new_i++;
+	  old_i++;
+	}
+      else if (old_uid < new_uid)
+	{
+	  /* If OLD_UID is less than NEW_UID, the old operand has
+	     disappeared, skip to the next old operand.  */
+	  old_i++;
+	}
+      else
+	{
+	  /* This is a new operand.  */
+	  VEC_safe_push (tree, heap, new_ops, new_op);
+	  new_i++;
+	}
+    }
+
+  /* If there is anything remaining in the build_vuses list, simply emit it.  */
+  for ( ; new_i < VEC_length (tree, build_vuses); new_i++)
+    VEC_safe_push (tree, heap, new_ops, VEC_index (tree, build_vuses, new_i));
+
+  /* If there is anything in the old list, free it.  */
+  if (old_ops)
+    {
+      for (old_i = 0; old_i < VUSE_NUM (old_ops); old_i++)
+	delink_imm_use (VUSE_OP_PTR (old_ops, old_i));
+      add_vop_to_freelist (old_ops);
+      gimple_set_vuse_ops (stmt, NULL);
+    }
+
+  /* If there are any operands, instantiate a VUSE operator for STMT.  */
+  if (new_ops)
+    {
+      tree op;
+      unsigned i;
+
+      last = add_vuse_op (stmt, NULL, VEC_length (tree, new_ops), NULL);
+
+      for (i = 0; VEC_iterate (tree, new_ops, i, op); i++)
+	SET_USE (VUSE_OP_PTR (last, (int) i), op);
+
+      gimple_set_vuse_ops (stmt, last);
+      VEC_free (tree, heap, new_ops);
+    }
+
+#ifdef ENABLE_CHECKING
+  {
+    unsigned x;
+    
+    if (gimple_vuse_ops (stmt))
+      {
+	gcc_assert (gimple_vuse_ops (stmt)->next == NULL);
+	x = VUSE_NUM (gimple_vuse_ops (stmt));
+      }
+    else
+      x = 0;
+
+    gcc_assert (x == VEC_length (tree, build_vuses));
+  }
+#endif
+}
+
+/* Return a new VUSE operand vector for STMT.  */
+                                                                              
+static void
+finalize_ssa_vuses (gimple stmt)
+{
+  unsigned num, num_vdefs;
+  unsigned vuse_index;
+
+  /* Remove superfluous VUSE operands.  If the statement already has a
+     VDEF operator for a variable 'a', then a VUSE for 'a' is not
+     needed because VDEFs imply a VUSE of the variable.  For instance,
+     suppose that variable 'a' is pointed-to by p and q:
+
+	      # VUSE <a_2>
+	      # a_3 = VDEF <a_2>
+	      *p = *q;
+
+     The VUSE <a_2> is superfluous because it is implied by the
+     VDEF operator.  */
+  num = VEC_length (tree, build_vuses);
+  num_vdefs = VEC_length (tree, build_vdefs);
+
+  if (num > 0 && num_vdefs > 0)
+    for (vuse_index = 0; vuse_index < VEC_length (tree, build_vuses); )
+      {
+	tree vuse;
+	vuse = VEC_index (tree, build_vuses, vuse_index);
+	if (TREE_CODE (vuse) != SSA_NAME)
+	  {
+	    var_ann_t ann = var_ann (vuse);
+	    ann->in_vuse_list = 0;
+	    if (ann->in_vdef_list)
+	      {
+		VEC_ordered_remove (tree, build_vuses, vuse_index);
+		continue;
+	      }
+	  }
+	vuse_index++;
+      }
+
+  finalize_ssa_vuse_ops (stmt);
+}
+
+
+/* Clear the in_list bits and empty the build array for VDEFs and
+   VUSEs.  */
+
+static inline void
+cleanup_build_arrays (void)
+{
+  unsigned i;
+  tree t;
+
+  for (i = 0; VEC_iterate (tree, build_vdefs, i, t); i++)
+    if (TREE_CODE (t) != SSA_NAME)
+      var_ann (t)->in_vdef_list = false;
+
+  for (i = 0; VEC_iterate (tree, build_vuses, i, t); i++)
+    if (TREE_CODE (t) != SSA_NAME)
+      var_ann (t)->in_vuse_list = false;
+
+  VEC_truncate (tree, build_vdefs, 0);
+  VEC_truncate (tree, build_vuses, 0);
+  VEC_truncate (tree, build_defs, 0);
+  VEC_truncate (tree, build_uses, 0);
+  bitmap_clear (build_loads);
+  bitmap_clear (build_stores);
+}
+
+
+/* Finalize all the build vectors, fill the new ones into INFO.  */
+                                                                              
+static inline void
+finalize_ssa_stmt_operands (gimple stmt)
+{
+  finalize_ssa_defs (stmt);
+  finalize_ssa_uses (stmt);
+  if (gimple_has_mem_ops (stmt))
+    {
+      finalize_ssa_vdefs (stmt);
+      finalize_ssa_vuses (stmt);
+    }
+  cleanup_build_arrays ();
+}
+
+
+/* Start the process of building up operands vectors in INFO.  */
+
+static inline void
+start_ssa_stmt_operands (void)
+{
+  gcc_assert (VEC_length (tree, build_defs) == 0);
+  gcc_assert (VEC_length (tree, build_uses) == 0);
+  gcc_assert (VEC_length (tree, build_vuses) == 0);
+  gcc_assert (VEC_length (tree, build_vdefs) == 0);
+  gcc_assert (bitmap_empty_p (build_loads));
+  gcc_assert (bitmap_empty_p (build_stores));
+}
+
+
+/* Add DEF_P to the list of pointers to operands.  */
+
+static inline void
+append_def (tree *def_p)
+{
+  VEC_safe_push (tree, heap, build_defs, (tree) def_p);
+}
+
+
+/* Add USE_P to the list of pointers to operands.  */
+
+static inline void
+append_use (tree *use_p)
+{
+  VEC_safe_push (tree, heap, build_uses, (tree) use_p);
+}
+
+
+/* Add VAR to the set of variables that require a VDEF operator.  */
+
+static inline void
+append_vdef (tree var)
+{
+  tree sym;
+
+  if (TREE_CODE (var) != SSA_NAME)
+    {
+      tree mpt;
+      var_ann_t ann;
+
+      /* If VAR belongs to a memory partition, use it instead of VAR.  */
+      mpt = memory_partition (var);
+      if (mpt)
+	var = mpt;
+
+      /* Don't allow duplicate entries.  */
+      ann = get_var_ann (var);
+      if (ann->in_vdef_list)
+        return;
+
+      ann->in_vdef_list = true;
+      sym = var;
+    }
+  else
+    sym = SSA_NAME_VAR (var);
+
+  VEC_safe_push (tree, heap, build_vdefs, var);
+  bitmap_set_bit (build_stores, DECL_UID (sym));
+}
+
+
+/* Add VAR to the set of variables that require a VUSE operator.  */
+
+static inline void
+append_vuse (tree var)
+{
+  tree sym;
+
+  if (TREE_CODE (var) != SSA_NAME)
+    {
+      tree mpt;
+      var_ann_t ann;
+
+      /* If VAR belongs to a memory partition, use it instead of VAR.  */
+      mpt = memory_partition (var);
+      if (mpt)
+	var = mpt;
+
+      /* Don't allow duplicate entries.  */
+      ann = get_var_ann (var);
+      if (ann->in_vuse_list)
+	return;
+      else if (ann->in_vdef_list)
+       {
+         /* We don't want a vuse if we already have a vdef, but we must
+            still put this in build_loads.  */
+         bitmap_set_bit (build_loads, DECL_UID (var));
+         return;
+       }
+
+      ann->in_vuse_list = true;
+      sym = var;
+    }
+  else
+    sym = SSA_NAME_VAR (var);
+
+  VEC_safe_push (tree, heap, build_vuses, var);
+  bitmap_set_bit (build_loads, DECL_UID (sym));
+}
+
+
+/* REF is a tree that contains the entire pointer dereference
+   expression, if available, or NULL otherwise.  ALIAS is the variable
+   we are asking if REF can access.  OFFSET and SIZE come from the
+   memory access expression that generated this virtual operand.
+
+   XXX: We should handle the NO_ALIAS attributes here.  */
+
+static bool
+access_can_touch_variable (tree ref, tree alias, HOST_WIDE_INT offset,
+			   HOST_WIDE_INT size)
+{
+  bool offsetgtz = offset > 0;
+  unsigned HOST_WIDE_INT uoffset = (unsigned HOST_WIDE_INT) offset;
+  tree base = ref ? get_base_address (ref) : NULL;
+
+  /* If ALIAS is .GLOBAL_VAR then the memory reference REF must be
+     using a call-clobbered memory tag.  By definition, call-clobbered
+     memory tags can always touch .GLOBAL_VAR.  */
+  if (alias == gimple_global_var (cfun))
+    return true;
+
+  /* If ref is a TARGET_MEM_REF, just return true, as we can't really
+     disambiguate them right now.  */
+  if (ref && TREE_CODE (ref) == TARGET_MEM_REF)
+    return true;
+  
+  /* Without strict aliasing, it is impossible for a component access
+     through a pointer to touch a random variable, unless that
+     variable *is* a structure or a pointer.
+
+     That is, given p->c, and some random global variable b,
+     there is no legal way that p->c could be an access to b.
+     
+     Without strict aliasing on, we consider it legal to do something
+     like:
+
+     struct foos { int l; };
+     int foo;
+     static struct foos *getfoo(void);
+     int main (void)
+     {
+       struct foos *f = getfoo();
+       f->l = 1;
+       foo = 2;
+       if (f->l == 1)
+         abort();
+       exit(0);
+     }
+     static struct foos *getfoo(void)     
+     { return (struct foos *)&foo; }
+     
+     (taken from 20000623-1.c)
+
+     The docs also say/imply that access through union pointers
+     is legal (but *not* if you take the address of the union member,
+     i.e. the inverse), such that you can do
+
+     typedef union {
+       int d;
+     } U;
+
+     int rv;
+     void breakme()
+     {
+       U *rv0;
+       U *pretmp = (U*)&rv;
+       rv0 = pretmp;
+       rv0->d = 42;    
+     }
+     To implement this, we just punt on accesses through union
+     pointers entirely.
+
+     Another case we have to allow is accessing a variable
+     through an array access at offset zero.  This happens from
+     code generated by the fortran frontend like
+
+     char[1:1] & my_char_ref;
+     char my_char;
+     my_char_ref_1 = (char[1:1] &) &my_char;
+     D.874_2 = (*my_char_ref_1)[1]{lb: 1 sz: 1};
+  */
+  if (ref 
+      && flag_strict_aliasing
+      && TREE_CODE (ref) != INDIRECT_REF
+      && !MTAG_P (alias)
+      && base
+      && (TREE_CODE (base) != INDIRECT_REF
+	  || TREE_CODE (TREE_TYPE (base)) != UNION_TYPE)
+      && (TREE_CODE (base) != INDIRECT_REF
+	  || TREE_CODE (ref) != ARRAY_REF
+	  || offset != 0
+	  || (DECL_SIZE (alias)
+	      && TREE_CODE (DECL_SIZE (alias)) == INTEGER_CST
+	      && size != -1
+	      && (unsigned HOST_WIDE_INT)size
+	      != TREE_INT_CST_LOW (DECL_SIZE (alias))))
+      && !AGGREGATE_TYPE_P (TREE_TYPE (alias))
+      && TREE_CODE (TREE_TYPE (alias)) != COMPLEX_TYPE
+      && !var_ann (alias)->is_heapvar
+      /* When the struct has may_alias attached to it, we need not to
+	 return true.  */
+      && get_alias_set (base))
+    {
+#ifdef ACCESS_DEBUGGING
+      fprintf (stderr, "Access to ");
+      print_generic_expr (stderr, ref, 0);
+      fprintf (stderr, " may not touch ");
+      print_generic_expr (stderr, alias, 0);
+      fprintf (stderr, " in function %s\n", get_name (current_function_decl));
+#endif
+      return false;
+    }
+
+  /* If the offset of the access is greater than the size of one of
+     the possible aliases, it can't be touching that alias, because it
+     would be past the end of the structure.  */
+  else if (ref
+	   && flag_strict_aliasing
+	   && TREE_CODE (ref) != INDIRECT_REF
+	   && !MTAG_P (alias)
+	   && !var_ann (alias)->is_heapvar
+	   && !POINTER_TYPE_P (TREE_TYPE (alias))
+	   && offsetgtz
+	   && DECL_SIZE (alias)
+	   && TREE_CODE (DECL_SIZE (alias)) == INTEGER_CST
+	   && uoffset >= TREE_INT_CST_LOW (DECL_SIZE (alias)))
+    {
+#ifdef ACCESS_DEBUGGING
+      fprintf (stderr, "Access to ");
+      print_generic_expr (stderr, ref, 0);
+      fprintf (stderr, " may not touch ");
+      print_generic_expr (stderr, alias, 0);
+      fprintf (stderr, " in function %s\n", get_name (current_function_decl));
+#endif
+      return false;
+    }	   
+
+  return true;
+}
+
+/* Add VAR to the virtual operands for STMT.  FLAGS is as in
+   get_expr_operands.  FULL_REF is a tree that contains the entire
+   pointer dereference expression, if available, or NULL otherwise.
+   OFFSET and SIZE come from the memory access expression that
+   generated this virtual operand.  IS_CALL_SITE is true if the
+   affected statement is a call site.  */
+
+static void
+add_virtual_operand (tree var, gimple stmt, int flags,
+		     tree full_ref, HOST_WIDE_INT offset,
+		     HOST_WIDE_INT size, bool is_call_site)
+{
+  bitmap aliases = NULL;
+  tree sym;
+  var_ann_t v_ann;
+  
+  sym = (TREE_CODE (var) == SSA_NAME ? SSA_NAME_VAR (var) : var);
+  v_ann = var_ann (sym);
+  
+  /* Mark the statement as having memory operands.  */
+  gimple_set_references_memory (stmt, true);
+
+  /* If the variable cannot be modified and this is a VDEF change
+     it into a VUSE.  This happens when read-only variables are marked
+     call-clobbered and/or aliased to writable variables.  So we only
+     check that this only happens on non-specific stores.
+
+     Note that if this is a specific store, i.e. associated with a
+     MODIFY_EXPR, then we can't suppress the VDEF, lest we run
+     into validation problems.
+
+     This can happen when programs cast away const, leaving us with a
+     store to read-only memory.  If the statement is actually executed
+     at runtime, then the program is ill formed.  If the statement is
+     not executed then all is well.  At the very least, we cannot ICE.  */
+  if ((flags & opf_implicit) && unmodifiable_var_p (var))
+    flags &= ~opf_def;
+  
+  /* The variable is not a GIMPLE register.  Add it (or its aliases) to
+     virtual operands, unless the caller has specifically requested
+     not to add virtual operands (used when adding operands inside an
+     ADDR_EXPR expression).  */
+  if (flags & opf_no_vops)
+    return;
+  
+  if (MTAG_P (var))
+    aliases = MTAG_ALIASES (var);
+
+  if (aliases == NULL)
+    {
+      if (!gimple_aliases_computed_p (cfun) && (flags & opf_def))
+	gimple_set_has_volatile_ops (stmt, true);
+
+      /* The variable is not aliased or it is an alias tag.  */
+      if (flags & opf_def)
+	append_vdef (var);
+      else
+	append_vuse (var);
+    }
+  else
+    {
+      bitmap_iterator bi;
+      unsigned int i;
+      bool none_added = true;
+      
+      /* The variable is aliased.  Add its aliases to the virtual
+	 operands.  */
+      gcc_assert (!bitmap_empty_p (aliases));
+
+      EXECUTE_IF_SET_IN_BITMAP (aliases, 0, i, bi)
+	{
+	  tree al = referenced_var (i);
+
+	  /* Call-clobbered tags may have non-call-clobbered
+	     symbols in their alias sets.  Ignore them if we are
+	     adding VOPs for a call site.  */
+	  if (is_call_site && !is_call_clobbered (al))
+	    continue;
+
+	  /* If we do not know the full reference tree or if the access is
+	     unspecified [0, -1], we cannot prune it.  Otherwise try doing
+	     so using access_can_touch_variable.  */
+	  if (full_ref
+	      && !access_can_touch_variable (full_ref, al, offset, size))
+	    continue;
+
+	  if (flags & opf_def)
+	    append_vdef (al);
+	  else
+	    append_vuse (al);
+	  none_added = false;
+	}
+
+      if (flags & opf_def)
+	{
+	  /* If the variable is also an alias tag, add a virtual
+	     operand for it, otherwise we will miss representing
+	     references to the members of the variable's alias set.	     
+	     This fixes the bug in gcc.c-torture/execute/20020503-1.c.
+	     
+	     It is also necessary to add bare defs on clobbers for
+	     SMT's, so that bare SMT uses caused by pruning all the
+	     aliases will link up properly with calls.   In order to
+	     keep the number of these bare defs we add down to the
+	     minimum necessary, we keep track of which SMT's were used
+	     alone in statement vdefs or VUSEs.  */
+	  if (none_added
+	      || (TREE_CODE (var) == SYMBOL_MEMORY_TAG
+		  && is_call_site))
+	    append_vdef (var);
+	}
+      else
+	{
+	  /* Even if no aliases have been added, we still need to
+	     establish def-use and use-def chains, lest
+	     transformations think that this is not a memory
+	     reference.  For an example of this scenario, see
+	     testsuite/g++.dg/opt/cleanup1.C.  */
+	  if (none_added)
+	    append_vuse (var);
+	}
+    }
+}
+
+
+/* Add *VAR_P to the appropriate operand array for statement STMT.
+   FLAGS is as in get_expr_operands.  If *VAR_P is a GIMPLE register,
+   it will be added to the statement's real operands, otherwise it is
+   added to virtual operands.  */
+
+static void
+add_stmt_operand (tree *var_p, gimple stmt, int flags)
+{
+  tree var, sym;
+  var_ann_t v_ann;
+
+  gcc_assert (SSA_VAR_P (*var_p));
+
+  var = *var_p;
+  sym = (TREE_CODE (var) == SSA_NAME ? SSA_NAME_VAR (var) : var);
+  v_ann = var_ann (sym);
+
+  /* Mark statements with volatile operands.  */
+  if (TREE_THIS_VOLATILE (sym))
+    gimple_set_has_volatile_ops (stmt, true);
+
+  if (is_gimple_reg (sym))
+    {
+      /* The variable is a GIMPLE register.  Add it to real operands.  */
+      if (flags & opf_def)
+	append_def (var_p);
+      else
+	append_use (var_p);
+    }
+  else
+    add_virtual_operand (var, stmt, flags, NULL_TREE, 0, -1, false);
+}
+
+/* Subroutine of get_indirect_ref_operands.  ADDR is the address
+   that is dereferenced, the meaning of the rest of the arguments
+   is the same as in get_indirect_ref_operands.  */
+
+static void
+get_addr_dereference_operands (gimple stmt, tree *addr, int flags,
+			       tree full_ref, HOST_WIDE_INT offset,
+			       HOST_WIDE_INT size, bool recurse_on_base)
+{
+  tree ptr = *addr;
+
+  /* Mark the statement as having memory operands.  */
+  gimple_set_references_memory (stmt, true);
+
+  if (SSA_VAR_P (ptr))
+    {
+      struct ptr_info_def *pi = NULL;
+
+      /* If PTR has flow-sensitive points-to information, use it.  */
+      if (TREE_CODE (ptr) == SSA_NAME
+	  && (pi = SSA_NAME_PTR_INFO (ptr)) != NULL
+	  && pi->name_mem_tag)
+	{
+	  /* PTR has its own memory tag.  Use it.  */
+	  add_virtual_operand (pi->name_mem_tag, stmt, flags,
+			       full_ref, offset, size, false);
+	}
+      else
+	{
+	  /* If PTR is not an SSA_NAME or it doesn't have a name
+	     tag, use its symbol memory tag.  */
+	  var_ann_t v_ann;
+
+	  /* If we are emitting debugging dumps, display a warning if
+	     PTR is an SSA_NAME with no flow-sensitive alias
+	     information.  That means that we may need to compute
+	     aliasing again or that a propagation pass forgot to
+	     update the alias information on the pointers.  */
+	  if (dump_file
+	      && TREE_CODE (ptr) == SSA_NAME
+	      && (pi == NULL
+		  || (pi->name_mem_tag == NULL_TREE
+		      && !pi->pt_anything))
+	      && gimple_aliases_computed_p (cfun))
+	    {
+	      fprintf (dump_file,
+		  "NOTE: no flow-sensitive alias info for ");
+	      print_generic_expr (dump_file, ptr, dump_flags);
+	      fprintf (dump_file, " in ");
+	      print_gimple_stmt (dump_file, stmt, 0, 0);
+	    }
+
+	  if (TREE_CODE (ptr) == SSA_NAME)
+	    ptr = SSA_NAME_VAR (ptr);
+	  v_ann = var_ann (ptr);
+
+	  /* If we don't know what this pointer points to then we have
+	     to make sure to not prune virtual operands based on offset
+	     and size.  */
+	  if (v_ann->symbol_mem_tag)
+	    {
+	      add_virtual_operand (v_ann->symbol_mem_tag, stmt, flags,
+				   full_ref, 0, -1, false);
+	      /* Make sure we add the SMT itself.  */
+	      if (!(flags & opf_no_vops))
+		{
+		  if (flags & opf_def)
+		    append_vdef (v_ann->symbol_mem_tag);
+		  else
+		    append_vuse (v_ann->symbol_mem_tag);
+		}
+	    }
+
+	  /* Aliasing information is missing; mark statement as
+	     volatile so we won't optimize it out too actively.  */
+          else if (!gimple_aliases_computed_p (cfun)
+                   && (flags & opf_def))
+	    gimple_set_has_volatile_ops (stmt, true);
+	}
+    }
+  else if (TREE_CODE (ptr) == INTEGER_CST)
+    {
+      /* If a constant is used as a pointer, we can't generate a real
+	 operand for it but we mark the statement volatile to prevent
+	 optimizations from messing things up.  */
+      gimple_set_has_volatile_ops (stmt, true);
+      return;
+    }
+  else
+    {
+      /* Ok, this isn't even is_gimple_min_invariant.  Something's broke.  */
+      gcc_unreachable ();
+    }
+
+  /* If requested, add a USE operand for the base pointer.  */
+  if (recurse_on_base)
+    get_expr_operands (stmt, addr, opf_use);
+}
+
+
+/* A subroutine of get_expr_operands to handle INDIRECT_REF,
+   ALIGN_INDIRECT_REF and MISALIGNED_INDIRECT_REF.  
+
+   STMT is the statement being processed, EXPR is the INDIRECT_REF
+      that got us here.
+   
+   FLAGS is as in get_expr_operands.
+
+   FULL_REF contains the full pointer dereference expression, if we
+      have it, or NULL otherwise.
+
+   OFFSET and SIZE are the location of the access inside the
+      dereferenced pointer, if known.
+
+   RECURSE_ON_BASE should be set to true if we want to continue
+      calling get_expr_operands on the base pointer, and false if
+      something else will do it for us.  */
+
+static void
+get_indirect_ref_operands (gimple stmt, tree expr, int flags, tree full_ref,
+			   HOST_WIDE_INT offset, HOST_WIDE_INT size,
+			   bool recurse_on_base)
+{
+  tree *pptr = &TREE_OPERAND (expr, 0);
+
+  if (TREE_THIS_VOLATILE (expr))
+    gimple_set_has_volatile_ops (stmt, true);
+
+  get_addr_dereference_operands (stmt, pptr, flags, full_ref, offset, size,
+				 recurse_on_base);
+}
+
+
+/* A subroutine of get_expr_operands to handle TARGET_MEM_REF.  */
+
+static void
+get_tmr_operands (gimple stmt, tree expr, int flags)
+{
+  tree tag;
+
+  /* Mark the statement as having memory operands.  */
+  gimple_set_references_memory (stmt, true);
+
+  /* First record the real operands.  */
+  get_expr_operands (stmt, &TMR_BASE (expr), opf_use);
+  get_expr_operands (stmt, &TMR_INDEX (expr), opf_use);
+
+  if (TMR_SYMBOL (expr))
+    gimple_add_to_addresses_taken (stmt, TMR_SYMBOL (expr));
+
+  tag = TMR_TAG (expr);
+  if (!tag)
+    {
+      /* Something weird, so ensure that we will be careful.  */
+      gimple_set_has_volatile_ops (stmt, true);
+      return;
+    }
+  if (!MTAG_P (tag))
+    {
+      get_expr_operands (stmt, &tag, flags);
+      return;
+    }
+
+  add_virtual_operand (tag, stmt, flags, expr, 0, -1, false);
+}
+
+
+/* Add clobbering definitions for .GLOBAL_VAR or for each of the call
+   clobbered variables in the function.  */
+
+static void
+add_call_clobber_ops (gimple stmt, tree callee ATTRIBUTE_UNUSED)
+{
+  unsigned u;
+  bitmap_iterator bi;
+  bitmap not_read_b, not_written_b;
+
+  gcc_assert (!(gimple_call_flags (stmt) & (ECF_PURE | ECF_CONST)));
+
+  /* If we created .GLOBAL_VAR earlier, just use it.  */
+  if (gimple_global_var (cfun))
+    {
+      tree var = gimple_global_var (cfun);
+      add_virtual_operand (var, stmt, opf_def, NULL, 0, -1, true);
+      return;
+    }
+
+  /* Get info for local and module level statics.  There is a bit
+     set for each static if the call being processed does not read
+     or write that variable.  */
+  not_read_b = callee ? ipa_reference_get_not_read_global (cgraph_node (callee)) : NULL; 
+  not_written_b = callee ? ipa_reference_get_not_written_global (cgraph_node (callee)) : NULL;
+
+  /* Add a VDEF operand for every call clobbered variable.  */
+  EXECUTE_IF_SET_IN_BITMAP (gimple_call_clobbered_vars (cfun), 0, u, bi)
+    {
+      tree var = referenced_var_lookup (u);
+      tree real_var = var;
+      bool not_read;
+      bool not_written;
+
+      not_read = not_read_b
+	         ? bitmap_bit_p (not_read_b, DECL_UID (real_var))
+	         : false;
+
+      not_written = not_written_b
+	            ? bitmap_bit_p (not_written_b, DECL_UID (real_var))
+		    : false;
+      gcc_assert (!unmodifiable_var_p (var));
+      
+      clobber_stats.clobbered_vars++;
+
+      /* See if this variable is really clobbered by this function.  */
+
+      if (not_written)
+	{
+	  clobber_stats.static_write_clobbers_avoided++;
+	  if (!not_read)
+	    add_virtual_operand (var, stmt, opf_use, NULL, 0, -1, true);
+	  else
+	    clobber_stats.static_read_clobbers_avoided++;
+	}
+      else
+	add_virtual_operand (var, stmt, opf_def, NULL, 0, -1, true);
+    }
+}
+
+
+/* Add VUSE operands for .GLOBAL_VAR or all call clobbered variables in the
+   function.  */
+
+static void
+add_call_read_ops (gimple stmt, tree callee ATTRIBUTE_UNUSED)
+{
+  unsigned u;
+  bitmap_iterator bi;
+  bitmap not_read_b;
+
+  /* Const functions do not reference memory.  */
+  if (gimple_call_flags (stmt) & ECF_CONST)
+    return;
+
+  not_read_b = callee ? ipa_reference_get_not_read_global (cgraph_node (callee)) : NULL;
+
+  /* For pure functions we compute non-escaped uses separately.  */
+  if (gimple_call_flags (stmt) & ECF_PURE)
+    EXECUTE_IF_SET_IN_BITMAP (gimple_call_used_vars (cfun), 0, u, bi)
+      {
+	tree var = referenced_var_lookup (u);
+	tree real_var = var;
+	bool not_read;
+
+	if (unmodifiable_var_p (var))
+	  continue;
+
+	not_read = not_read_b
+	    ? bitmap_bit_p (not_read_b, DECL_UID (real_var))
+	    : false;
+
+	clobber_stats.readonly_clobbers++;
+
+	/* See if this variable is really used by this function.  */
+	if (!not_read)
+	  add_virtual_operand (var, stmt, opf_use, NULL, 0, -1, true);
+	else
+	  clobber_stats.static_readonly_clobbers_avoided++;
+      }
+
+  /* Add a VUSE for .GLOBAL_VAR if it has been created.  See
+     add_referenced_var for the heuristic used to decide whether to
+     create .GLOBAL_VAR.  */
+  if (gimple_global_var (cfun))
+    {
+      tree var = gimple_global_var (cfun);
+      add_virtual_operand (var, stmt, opf_use, NULL, 0, -1, true);
+      return;
+    }
+
+  /* Add a VUSE for each call-clobbered variable.  */
+  EXECUTE_IF_SET_IN_BITMAP (gimple_call_clobbered_vars (cfun), 0, u, bi)
+    {
+      tree var = referenced_var (u);
+      tree real_var = var;
+      bool not_read;
+      
+      clobber_stats.readonly_clobbers++;
+
+      not_read = not_read_b ? bitmap_bit_p (not_read_b, DECL_UID (real_var))
+	                    : false;
+      
+      if (not_read)
+	{
+	  clobber_stats.static_readonly_clobbers_avoided++;
+	  continue;
+	}
+            
+      add_virtual_operand (var, stmt, opf_use, NULL, 0, -1, true);
+    }
+}
+
+
+/* If STMT is a call that may clobber globals and other symbols that
+   escape, add them to the VDEF/VUSE lists for it.  */
+
+static void
+maybe_add_call_clobbered_vops (gimple stmt)
+{
+  int call_flags = gimple_call_flags (stmt);
+
+  /* Mark the statement as having memory operands.  */
+  gimple_set_references_memory (stmt, true);
+
+  /* If aliases have been computed already, add VDEF or VUSE
+     operands for all the symbols that have been found to be
+     call-clobbered.  */
+  if (gimple_aliases_computed_p (cfun) && !(call_flags & ECF_NOVOPS))
+    {
+      /* A 'pure' or a 'const' function never call-clobbers anything. 
+	 A 'noreturn' function might, but since we don't return anyway 
+	 there is no point in recording that.  */ 
+      if (!(call_flags & (ECF_PURE | ECF_CONST | ECF_NORETURN)))
+	add_call_clobber_ops (stmt, gimple_call_fndecl (stmt));
+      else if (!(call_flags & ECF_CONST))
+	add_call_read_ops (stmt, gimple_call_fndecl (stmt));
+    }
+}
+
+
+/* Scan operands in the ASM_EXPR stmt referred to in INFO.  */
+
+static void
+get_asm_expr_operands (gimple stmt)
+{
+  size_t i, noutputs;
+  const char **oconstraints;
+  const char *constraint;
+  bool allows_mem, allows_reg, is_inout;
+
+  noutputs = gimple_asm_noutputs (stmt);
+  oconstraints = (const char **) alloca ((noutputs) * sizeof (const char *));
+
+  /* Gather all output operands.  */
+  for (i = 0; i < gimple_asm_noutputs (stmt); i++)
+    {
+      tree link = gimple_asm_output_op (stmt, i);
+      constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (link)));
+      oconstraints[i] = constraint;
+      parse_output_constraint (&constraint, i, 0, 0, &allows_mem,
+	                       &allows_reg, &is_inout);
+
+      /* This should have been split in gimplify_asm_expr.  */
+      gcc_assert (!allows_reg || !is_inout);
+
+      /* Memory operands are addressable.  Note that STMT needs the
+	 address of this operand.  */
+      if (!allows_reg && allows_mem)
+	{
+	  tree t = get_base_address (TREE_VALUE (link));
+	  if (t && DECL_P (t))
+	    gimple_add_to_addresses_taken (stmt, t);
+	}
+
+      get_expr_operands (stmt, &TREE_VALUE (link), opf_def);
+    }
+
+  /* Gather all input operands.  */
+  for (i = 0; i < gimple_asm_ninputs (stmt); i++)
+    {
+      tree link = gimple_asm_input_op (stmt, i);
+      constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (link)));
+      parse_input_constraint (&constraint, 0, 0, noutputs, 0, oconstraints,
+	                      &allows_mem, &allows_reg);
+
+      /* Memory operands are addressable.  Note that STMT needs the
+	 address of this operand.  */
+      if (!allows_reg && allows_mem)
+	{
+	  tree t = get_base_address (TREE_VALUE (link));
+	  if (t && DECL_P (t))
+	    gimple_add_to_addresses_taken (stmt, t);
+	}
+
+      get_expr_operands (stmt, &TREE_VALUE (link), 0);
+    }
+
+  /* Clobber all memory and addressable symbols for asm ("" : : : "memory");  */
+  for (i = 0; i < gimple_asm_nclobbers (stmt); i++)
+    {
+      tree link = gimple_asm_clobber_op (stmt, i);
+      if (strcmp (TREE_STRING_POINTER (TREE_VALUE (link)), "memory") == 0)
+	{
+	  unsigned i;
+	  bitmap_iterator bi;
+
+	  /* Mark the statement as having memory operands.  */
+	  gimple_set_references_memory (stmt, true);
+
+	  EXECUTE_IF_SET_IN_BITMAP (gimple_call_clobbered_vars (cfun), 0, i, bi)
+	    {
+	      tree var = referenced_var (i);
+	      add_stmt_operand (&var, stmt, opf_def | opf_implicit);
+	    }
+
+	  EXECUTE_IF_SET_IN_BITMAP (gimple_addressable_vars (cfun), 0, i, bi)
+	    {
+	      tree var = referenced_var (i);
+	      add_stmt_operand (&var, stmt, opf_def | opf_implicit);
+	    }
+	  break;
+	}
+    }
+}
+
+
+/* Recursively scan the expression pointed to by EXPR_P in statement
+   STMT.  FLAGS is one of the OPF_* constants modifying how to
+   interpret the operands found.  */
+
+static void
+get_expr_operands (gimple stmt, tree *expr_p, int flags)
+{
+  enum tree_code code;
+  enum tree_code_class codeclass;
+  tree expr = *expr_p;
+
+  if (expr == NULL)
+    return;
+
+  code = TREE_CODE (expr);
+  codeclass = TREE_CODE_CLASS (code);
+
+  switch (code)
+    {
+    case ADDR_EXPR:
+      /* Taking the address of a variable does not represent a
+	 reference to it, but the fact that the statement takes its
+	 address will be of interest to some passes (e.g. alias
+	 resolution).  */
+      gimple_add_to_addresses_taken (stmt, TREE_OPERAND (expr, 0));
+
+      /* If the address is invariant, there may be no interesting
+	 variable references inside.  */
+      if (is_gimple_min_invariant (expr))
+	return;
+
+      /* Otherwise, there may be variables referenced inside but there
+	 should be no VUSEs created, since the referenced objects are
+	 not really accessed.  The only operands that we should find
+	 here are ARRAY_REF indices which will always be real operands
+	 (GIMPLE does not allow non-registers as array indices).  */
+      flags |= opf_no_vops;
+      get_expr_operands (stmt, &TREE_OPERAND (expr, 0), flags);
+      return;
+
+    case SSA_NAME:
+    case SYMBOL_MEMORY_TAG:
+    case NAME_MEMORY_TAG:
+     add_stmt_operand (expr_p, stmt, flags);
+     return;
+
+    case VAR_DECL:
+    case PARM_DECL:
+    case RESULT_DECL:
+      add_stmt_operand (expr_p, stmt, flags);
+      return;
+
+    case MISALIGNED_INDIRECT_REF:
+      get_expr_operands (stmt, &TREE_OPERAND (expr, 1), flags);
+      /* fall through */
+
+    case ALIGN_INDIRECT_REF:
+    case INDIRECT_REF:
+      get_indirect_ref_operands (stmt, expr, flags, expr, 0, -1, true);
+      return;
+
+    case TARGET_MEM_REF:
+      get_tmr_operands (stmt, expr, flags);
+      return;
+
+    case ARRAY_REF:
+    case ARRAY_RANGE_REF:
+    case COMPONENT_REF:
+    case REALPART_EXPR:
+    case IMAGPART_EXPR:
+      {
+	tree ref;
+	HOST_WIDE_INT offset, size, maxsize;
+
+	if (TREE_THIS_VOLATILE (expr))
+	  gimple_set_has_volatile_ops (stmt, true);
+
+	ref = get_ref_base_and_extent (expr, &offset, &size, &maxsize);
+	if (TREE_CODE (ref) == INDIRECT_REF)
+	  {
+	    get_indirect_ref_operands (stmt, ref, flags, expr, offset,
+		                       maxsize, false);
+	    flags |= opf_no_vops;
+	  }
+
+	get_expr_operands (stmt, &TREE_OPERAND (expr, 0), flags);
+	
+	if (code == COMPONENT_REF)
+	  {
+	    if (TREE_THIS_VOLATILE (TREE_OPERAND (expr, 1)))
+	      gimple_set_has_volatile_ops (stmt, true);
+	    get_expr_operands (stmt, &TREE_OPERAND (expr, 2), opf_use);
+	  }
+	else if (code == ARRAY_REF || code == ARRAY_RANGE_REF)
+	  {
+            get_expr_operands (stmt, &TREE_OPERAND (expr, 1), opf_use);
+            get_expr_operands (stmt, &TREE_OPERAND (expr, 2), opf_use);
+            get_expr_operands (stmt, &TREE_OPERAND (expr, 3), opf_use);
+	  }
+
+	return;
+      }
+
+    case WITH_SIZE_EXPR:
+      /* WITH_SIZE_EXPR is a pass-through reference to its first argument,
+	 and an rvalue reference to its second argument.  */
+      get_expr_operands (stmt, &TREE_OPERAND (expr, 1), opf_use);
+      get_expr_operands (stmt, &TREE_OPERAND (expr, 0), flags);
+      return;
+
+    case COND_EXPR:
+    case VEC_COND_EXPR:
+      get_expr_operands (stmt, &TREE_OPERAND (expr, 0), opf_use);
+      get_expr_operands (stmt, &TREE_OPERAND (expr, 1), opf_use);
+      get_expr_operands (stmt, &TREE_OPERAND (expr, 2), opf_use);
+      return;
+
+    case CONSTRUCTOR:
+      {
+	/* General aggregate CONSTRUCTORs have been decomposed, but they
+	   are still in use as the COMPLEX_EXPR equivalent for vectors.  */
+	constructor_elt *ce;
+	unsigned HOST_WIDE_INT idx;
+
+	for (idx = 0;
+	     VEC_iterate (constructor_elt, CONSTRUCTOR_ELTS (expr), idx, ce);
+	     idx++)
+	  get_expr_operands (stmt, &ce->value, opf_use);
+
+	return;
+      }
+
+    case BIT_FIELD_REF:
+      if (TREE_THIS_VOLATILE (expr))
+	gimple_set_has_volatile_ops (stmt, true);
+      /* FALLTHRU */
+
+    case TRUTH_NOT_EXPR:
+    case VIEW_CONVERT_EXPR:
+    do_unary:
+      get_expr_operands (stmt, &TREE_OPERAND (expr, 0), flags);
+      return;
+
+    case TRUTH_AND_EXPR:
+    case TRUTH_OR_EXPR:
+    case TRUTH_XOR_EXPR:
+    case COMPOUND_EXPR:
+    case OBJ_TYPE_REF:
+    case ASSERT_EXPR:
+    do_binary:
+      {
+	get_expr_operands (stmt, &TREE_OPERAND (expr, 0), flags);
+	get_expr_operands (stmt, &TREE_OPERAND (expr, 1), flags);
+	return;
+      }
+
+    case DOT_PROD_EXPR:
+    case REALIGN_LOAD_EXPR:
+      {
+	get_expr_operands (stmt, &TREE_OPERAND (expr, 0), flags);
+        get_expr_operands (stmt, &TREE_OPERAND (expr, 1), flags);
+        get_expr_operands (stmt, &TREE_OPERAND (expr, 2), flags);
+        return;
+      }
+
+    case CHANGE_DYNAMIC_TYPE_EXPR:
+      gcc_unreachable ();
+
+    case FUNCTION_DECL:
+    case LABEL_DECL:
+    case CONST_DECL:
+    case CASE_LABEL_EXPR:
+    case FILTER_EXPR:
+    case EXC_PTR_EXPR:
+      /* Expressions that make no memory references.  */
+      return;
+
+    default:
+      if (codeclass == tcc_unary)
+	goto do_unary;
+      if (codeclass == tcc_binary || codeclass == tcc_comparison)
+	goto do_binary;
+      if (codeclass == tcc_constant || codeclass == tcc_type)
+	return;
+    }
+
+  /* If we get here, something has gone wrong.  */
+#ifdef ENABLE_CHECKING
+  fprintf (stderr, "unhandled expression in get_expr_operands():\n");
+  debug_tree (expr);
+  fputs ("\n", stderr);
+#endif
+  gcc_unreachable ();
+}
+
+
+/* Parse STMT looking for operands.  When finished, the various
+   build_* operand vectors will have potential operands in them.  */
+
+static void
+parse_ssa_operands (gimple stmt)
+{
+  enum gimple_code code = gimple_code (stmt);
+
+  if (code == GIMPLE_ASM)
+    get_asm_expr_operands (stmt);
+  else
+    {
+      size_t i, start = 0;
+
+      if (code == GIMPLE_ASSIGN || code == GIMPLE_CALL)
+	{
+	  get_expr_operands (stmt, gimple_op_ptr (stmt, 0), opf_def);
+	  start = 1;
+	}
+
+      for (i = start; i < gimple_num_ops (stmt); i++)
+	get_expr_operands (stmt, gimple_op_ptr (stmt, i), opf_use);
+
+      /* Add call-clobbered operands, if needed.  */
+      if (code == GIMPLE_CALL)
+	maybe_add_call_clobbered_vops (stmt);
+    }
+}
+
+
+/* Create an operands cache for STMT.  */
+
+static void
+build_ssa_operands (gimple stmt)
+{
+  /* Initially assume that the statement has no volatile operands and
+     makes no memory references.  */
+  gimple_set_has_volatile_ops (stmt, false);
+  gimple_set_references_memory (stmt, false);
+
+  /* Just clear the bitmap so we don't end up reallocating it over and over.  */
+  if (gimple_addresses_taken (stmt))
+    bitmap_clear (gimple_addresses_taken (stmt));
+
+  start_ssa_stmt_operands ();
+  parse_ssa_operands (stmt);
+  operand_build_sort_virtual (build_vuses);
+  operand_build_sort_virtual (build_vdefs);
+  finalize_ssa_stmt_operands (stmt);
+
+  /* For added safety, assume that statements with volatile operands
+     also reference memory.  */
+  if (gimple_has_volatile_ops (stmt))
+    gimple_set_references_memory (stmt, true);
+}
+
+
+/* Releases the operands of STMT back to their freelists, and clears
+   the stmt operand lists.  */
+
+void
+free_stmt_operands (gimple stmt)
+{
+  def_optype_p defs = gimple_def_ops (stmt), last_def;
+  use_optype_p uses = gimple_use_ops (stmt), last_use;
+  voptype_p vuses = gimple_vuse_ops (stmt);
+  voptype_p vdefs = gimple_vdef_ops (stmt), vdef, next_vdef;
+  unsigned i;
+
+  if (defs)
+    {
+      for (last_def = defs; last_def->next; last_def = last_def->next)
+	continue;
+      last_def->next = gimple_ssa_operands (cfun)->free_defs;
+      gimple_ssa_operands (cfun)->free_defs = defs;
+      gimple_set_def_ops (stmt, NULL);
+    }
+
+  if (uses)
+    {
+      for (last_use = uses; last_use->next; last_use = last_use->next)
+	delink_imm_use (USE_OP_PTR (last_use));
+      delink_imm_use (USE_OP_PTR (last_use));
+      last_use->next = gimple_ssa_operands (cfun)->free_uses;
+      gimple_ssa_operands (cfun)->free_uses = uses;
+      gimple_set_use_ops (stmt, NULL);
+    }
+
+  if (vuses)
+    {
+      for (i = 0; i < VUSE_NUM (vuses); i++)
+	delink_imm_use (VUSE_OP_PTR (vuses, i));
+      add_vop_to_freelist (vuses);
+      gimple_set_vuse_ops (stmt, NULL);
+    }
+
+  if (vdefs)
+    {
+      for (vdef = vdefs; vdef; vdef = next_vdef)
+	{
+	  next_vdef = vdef->next;
+	  delink_imm_use (VDEF_OP_PTR (vdef, 0));
+	  add_vop_to_freelist (vdef);
+	}
+      gimple_set_vdef_ops (stmt, NULL);
+    }
+
+  if (gimple_has_ops (stmt))
+    gimple_set_addresses_taken (stmt, NULL);
+
+  if (gimple_has_mem_ops (stmt))
+    {
+      gimple_set_stored_syms (stmt, NULL, &operands_bitmap_obstack);
+      gimple_set_loaded_syms (stmt, NULL, &operands_bitmap_obstack);
+    }
+}
+
+
+/* Get the operands of statement STMT.  */
+
+void
+update_stmt_operands (gimple stmt)
+{
+  /* If update_stmt_operands is called before SSA is initialized, do
+     nothing.  */
+  if (!ssa_operands_active ())
+    return;
+
+  timevar_push (TV_TREE_OPS);
+
+  gcc_assert (gimple_modified_p (stmt));
+  build_ssa_operands (stmt);
+  gimple_set_modified (stmt, false);
+
+  timevar_pop (TV_TREE_OPS);
+}
+
+
+/* Copies virtual operands from SRC to DST.  */
+
+void
+copy_virtual_operands (gimple dest, gimple src)
+{
+  unsigned int i, n;
+  voptype_p src_vuses, dest_vuses;
+  voptype_p src_vdefs, dest_vdefs;
+  struct voptype_d vuse;
+  struct voptype_d vdef;
+
+  if (!gimple_has_mem_ops (src))
+    return;
+
+  gimple_set_vdef_ops (dest, NULL);
+  gimple_set_vuse_ops (dest, NULL);
+
+  gimple_set_stored_syms (dest, gimple_stored_syms (src),
+			  &operands_bitmap_obstack);
+  gimple_set_loaded_syms (dest, gimple_loaded_syms (src),
+			  &operands_bitmap_obstack);
+
+  /* Copy all the VUSE operators and corresponding operands.  */
+  dest_vuses = &vuse;
+  for (src_vuses = gimple_vuse_ops (src);
+       src_vuses;
+       src_vuses = src_vuses->next)
+    {
+      n = VUSE_NUM (src_vuses);
+      dest_vuses = add_vuse_op (dest, NULL_TREE, n, dest_vuses);
+      for (i = 0; i < n; i++)
+	SET_USE (VUSE_OP_PTR (dest_vuses, i), VUSE_OP (src_vuses, i));
+
+      if (gimple_vuse_ops (dest) == NULL)
+	gimple_set_vuse_ops (dest, vuse.next);
+    }
+
+  /* Copy all the VDEF operators and corresponding operands.  */
+  dest_vdefs = &vdef;
+  for (src_vdefs = gimple_vdef_ops (src);
+       src_vdefs;
+       src_vdefs = src_vdefs->next)
+    {
+      n = VUSE_NUM (src_vdefs);
+      dest_vdefs = add_vdef_op (dest, NULL_TREE, n, dest_vdefs);
+      VDEF_RESULT (dest_vdefs) = VDEF_RESULT (src_vdefs);
+      for (i = 0; i < n; i++)
+	SET_USE (VUSE_OP_PTR (dest_vdefs, i), VUSE_OP (src_vdefs, i));
+
+      if (gimple_vdef_ops (dest) == NULL)
+	gimple_set_vdef_ops (dest, vdef.next);
+    }
+}
+
+
+/* Specifically for use in DOM's expression analysis.  Given a store, we
+   create an artificial stmt which looks like a load from the store, this can
+   be used to eliminate redundant loads.  OLD_OPS are the operands from the 
+   store stmt, and NEW_STMT is the new load which represents a load of the
+   values stored.  If DELINK_IMM_USES_P is specified, the immediate
+   uses of this stmt will be de-linked.  */
+
+void
+create_ssa_artificial_load_stmt (gimple new_stmt, gimple old_stmt,
+				 bool delink_imm_uses_p)
+{
+  tree op;
+  ssa_op_iter iter;
+  use_operand_p use_p;
+  unsigned i;
+
+  gimple_set_modified (new_stmt, false);
+
+  /* Process NEW_STMT looking for operands.  */
+  start_ssa_stmt_operands ();
+  parse_ssa_operands (new_stmt);
+
+  for (i = 0; VEC_iterate (tree, build_vuses, i, op); i++)
+    if (TREE_CODE (op) != SSA_NAME)
+      var_ann (op)->in_vuse_list = false;
+   
+  for (i = 0; VEC_iterate (tree, build_vdefs, i, op); i++)
+    if (TREE_CODE (op) != SSA_NAME)
+      var_ann (op)->in_vdef_list = false;
+
+  /* Remove any virtual operands that were found.  */
+  VEC_truncate (tree, build_vdefs, 0);
+  VEC_truncate (tree, build_vuses, 0);
+
+  /* Clear the loads and stores bitmaps.  */
+  bitmap_clear (build_loads);
+  bitmap_clear (build_stores);
+
+  /* For each VDEF on the original statement, we want to create a
+     VUSE of the VDEF result operand on the new statement.  */
+  FOR_EACH_SSA_TREE_OPERAND (op, old_stmt, iter, SSA_OP_VDEF)
+    append_vuse (op);
+
+  finalize_ssa_stmt_operands (new_stmt);
+
+  /* All uses in this fake stmt must not be in the immediate use lists.  */
+  if (delink_imm_uses_p)
+    FOR_EACH_SSA_USE_OPERAND (use_p, new_stmt, iter, SSA_OP_ALL_USES)
+      delink_imm_use (use_p);
+}
+
+
+/* Swap operands EXP0 and EXP1 in statement STMT.  No attempt is done
+   to test the validity of the swap operation.  */
+
+void
+swap_tree_operands (gimple stmt, tree *exp0, tree *exp1)
+{
+  tree op0, op1;
+  op0 = *exp0;
+  op1 = *exp1;
+
+  /* If the operand cache is active, attempt to preserve the relative
+     positions of these two operands in their respective immediate use
+     lists.  */
+  if (ssa_operands_active () && op0 != op1)
+    {
+      use_optype_p use0, use1, ptr;
+      use0 = use1 = NULL;
+
+      /* Find the 2 operands in the cache, if they are there.  */
+      for (ptr = gimple_use_ops (stmt); ptr; ptr = ptr->next)
+	if (USE_OP_PTR (ptr)->use == exp0)
+	  {
+	    use0 = ptr;
+	    break;
+	  }
+
+      for (ptr = gimple_use_ops (stmt); ptr; ptr = ptr->next)
+	if (USE_OP_PTR (ptr)->use == exp1)
+	  {
+	    use1 = ptr;
+	    break;
+	  }
+
+      /* If both uses don't have operand entries, there isn't much we can do
+         at this point.  Presumably we don't need to worry about it.  */
+      if (use0 && use1)
+        {
+	  tree *tmp = USE_OP_PTR (use1)->use;
+	  USE_OP_PTR (use1)->use = USE_OP_PTR (use0)->use;
+	  USE_OP_PTR (use0)->use = tmp;
+	}
+    }
+
+  /* Now swap the data.  */
+  *exp0 = op1;
+  *exp1 = op0;
+}
+
+/* Add the base address of REF to SET.  */
+
+void
+add_to_addressable_set (tree ref, bitmap *set)
+{
+  tree var;
+
+  /* Note that it is *NOT OKAY* to use the target of a COMPONENT_REF
+     as the only thing we take the address of.  If VAR is a structure,
+     taking the address of a field means that the whole structure may
+     be referenced using pointer arithmetic.  See PR 21407 and the
+     ensuing mailing list discussion.  */
+  var = get_base_address (ref);
+  if (var && SSA_VAR_P (var))
+    {
+      if (*set == NULL)
+	*set = BITMAP_ALLOC (&operands_bitmap_obstack);
+
+      bitmap_set_bit (*set, DECL_UID (var));
+      TREE_ADDRESSABLE (var) = 1;
+    }
+}
+
+
+/* Add the base address of REF to the set of addresses taken by STMT.
+   REF may be a single variable whose address has been taken or any
+   other valid GIMPLE memory reference (structure reference, array,
+   etc).  If the base address of REF is a decl that has sub-variables,
+   also add all of its sub-variables.  */
+
+void
+gimple_add_to_addresses_taken (gimple stmt, tree ref)
+{
+  gcc_assert (gimple_has_ops (stmt));
+  add_to_addressable_set (ref, gimple_addresses_taken_ptr (stmt));
+}
+
+
+/* Scan the immediate_use list for VAR making sure its linked properly.
+   Return TRUE if there is a problem and emit an error message to F.  */
+
+bool
+verify_imm_links (FILE *f, tree var)
+{
+  use_operand_p ptr, prev, list;
+  int count;
+
+  gcc_assert (TREE_CODE (var) == SSA_NAME);
+
+  list = &(SSA_NAME_IMM_USE_NODE (var));
+  gcc_assert (list->use == NULL);
+
+  if (list->prev == NULL)
+    {
+      gcc_assert (list->next == NULL);
+      return false;
+    }
+
+  prev = list;
+  count = 0;
+  for (ptr = list->next; ptr != list; )
+    {
+      if (prev != ptr->prev)
+	goto error;
+      
+      if (ptr->use == NULL)
+	goto error; /* 2 roots, or SAFE guard node.  */
+      else if (*(ptr->use) != var)
+	goto error;
+
+      prev = ptr;
+      ptr = ptr->next;
+
+      /* Avoid infinite loops.  50,000,000 uses probably indicates a
+	 problem.  */
+      if (count++ > 50000000)
+	goto error;
+    }
+
+  /* Verify list in the other direction.  */
+  prev = list;
+  for (ptr = list->prev; ptr != list; )
+    {
+      if (prev != ptr->next)
+	goto error;
+      prev = ptr;
+      ptr = ptr->prev;
+      if (count-- < 0)
+	goto error;
+    }
+
+  if (count != 0)
+    goto error;
+
+  return false;
+
+ error:
+  if (ptr->loc.stmt && gimple_modified_p (ptr->loc.stmt))
+    {
+      fprintf (f, " STMT MODIFIED. - <%p> ", (void *)ptr->loc.stmt);
+      print_gimple_stmt (f, ptr->loc.stmt, 0, TDF_SLIM);
+    }
+  fprintf (f, " IMM ERROR : (use_p : tree - %p:%p)", (void *)ptr, 
+	   (void *)ptr->use);
+  print_generic_expr (f, USE_FROM_PTR (ptr), TDF_SLIM);
+  fprintf(f, "\n");
+  return true;
+}
+
+
+/* Dump all the immediate uses to FILE.  */
+
+void
+dump_immediate_uses_for (FILE *file, tree var)
+{
+  imm_use_iterator iter;
+  use_operand_p use_p;
+
+  gcc_assert (var && TREE_CODE (var) == SSA_NAME);
+
+  print_generic_expr (file, var, TDF_SLIM);
+  fprintf (file, " : -->");
+  if (has_zero_uses (var))
+    fprintf (file, " no uses.\n");
+  else
+    if (has_single_use (var))
+      fprintf (file, " single use.\n");
+    else
+      fprintf (file, "%d uses.\n", num_imm_uses (var));
+
+  FOR_EACH_IMM_USE_FAST (use_p, iter, var)
+    {
+      if (use_p->loc.stmt == NULL && use_p->use == NULL)
+        fprintf (file, "***end of stmt iterator marker***\n");
+      else
+	if (!is_gimple_reg (USE_FROM_PTR (use_p)))
+	  print_gimple_stmt (file, USE_STMT (use_p), 0, TDF_VOPS|TDF_MEMSYMS);
+	else
+	  print_gimple_stmt (file, USE_STMT (use_p), 0, TDF_SLIM);
+    }
+  fprintf(file, "\n");
+}
+
+
+/* Dump all the immediate uses to FILE.  */
+
+void
+dump_immediate_uses (FILE *file)
+{
+  tree var;
+  unsigned int x;
+
+  fprintf (file, "Immediate_uses: \n\n");
+  for (x = 1; x < num_ssa_names; x++)
+    {
+      var = ssa_name(x);
+      if (!var)
+        continue;
+      dump_immediate_uses_for (file, var);
+    }
+}
+
+
+/* Dump def-use edges on stderr.  */
+
+void
+debug_immediate_uses (void)
+{
+  dump_immediate_uses (stderr);
+}
+
+
+/* Dump def-use edges on stderr.  */
+
+void
+debug_immediate_uses_for (tree var)
+{
+  dump_immediate_uses_for (stderr, var);
+}
+
+
+/* Create a new change buffer for the statement pointed by STMT_P and
+   push the buffer into SCB_STACK.  Each change buffer
+   records state information needed to determine what changed in the
+   statement.  Mainly, this keeps track of symbols that may need to be
+   put into SSA form, SSA name replacements and other information
+   needed to keep the SSA form up to date.  */
+
+void
+push_stmt_changes (gimple *stmt_p)
+{
+  gimple stmt;
+  scb_t buf;
+
+  stmt = *stmt_p;
+
+  /* It makes no sense to keep track of PHI nodes.  */
+  if (gimple_code (stmt) == GIMPLE_PHI)
+    return;
+
+  buf = XNEW (struct scb_d);
+  memset (buf, 0, sizeof *buf);
+
+  buf->stmt_p = stmt_p;
+
+  if (gimple_references_memory_p (stmt))
+    {
+      tree op;
+      ssa_op_iter i;
+
+      FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_VUSE)
+	{
+	  tree sym = TREE_CODE (op) == SSA_NAME ? SSA_NAME_VAR (op) : op;
+	  if (buf->loads == NULL)
+	    buf->loads = BITMAP_ALLOC (NULL);
+	  bitmap_set_bit (buf->loads, DECL_UID (sym));
+	}
+
+      FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_VDEF)
+	{
+	  tree sym = TREE_CODE (op) == SSA_NAME ? SSA_NAME_VAR (op) : op;
+	  if (buf->stores == NULL)
+	    buf->stores = BITMAP_ALLOC (NULL);
+	  bitmap_set_bit (buf->stores, DECL_UID (sym));
+	}
+    }
+
+  VEC_safe_push (scb_t, heap, scb_stack, buf);
+}
+
+
+/* Given two sets S1 and S2, mark the symbols that differ in S1 and S2
+   for renaming.  The set to mark for renaming is (S1 & ~S2) | (S2 & ~S1).  */
+
+static void
+mark_difference_for_renaming (bitmap s1, bitmap s2)
+{
+  if (s1 == NULL && s2 == NULL)
+    return;
+
+  if (s1 && s2 == NULL)
+    mark_set_for_renaming (s1);
+  else if (s1 == NULL && s2)
+    mark_set_for_renaming (s2);
+  else if (!bitmap_equal_p (s1, s2))
+    {
+      bitmap t1 = BITMAP_ALLOC (NULL);
+      bitmap_xor (t1, s1, s2);
+      mark_set_for_renaming (t1);
+      BITMAP_FREE (t1);
+    }
+}
+
+
+/* Pop the top SCB from SCB_STACK and act on the differences between
+   what was recorded by push_stmt_changes and the current state of
+   the statement.  */
+
+void
+pop_stmt_changes (gimple *stmt_p)
+{
+  tree op;
+  gimple stmt;
+  ssa_op_iter iter;
+  bitmap loads, stores;
+  scb_t buf;
+
+  stmt = *stmt_p;
+
+  /* It makes no sense to keep track of PHI nodes.  */
+  if (gimple_code (stmt) == GIMPLE_PHI)
+    return;
+
+  buf = VEC_pop (scb_t, scb_stack);
+  gcc_assert (stmt_p == buf->stmt_p);
+
+  /* Force an operand re-scan on the statement and mark any newly
+     exposed variables.  */
+  update_stmt (stmt);
+
+  /* Determine whether any memory symbols need to be renamed.  If the
+     sets of loads and stores are different after the statement is
+     modified, then the affected symbols need to be renamed.
+     
+     Note that it may be possible for the statement to not reference
+     memory anymore, but we still need to act on the differences in
+     the sets of symbols.  */
+  loads = stores = NULL;
+  if (gimple_references_memory_p (stmt))
+    {
+      tree op;
+      ssa_op_iter i;
+
+      FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_VUSE)
+	{
+	  tree sym = TREE_CODE (op) == SSA_NAME ? SSA_NAME_VAR (op) : op;
+	  if (loads == NULL)
+	    loads = BITMAP_ALLOC (NULL);
+	  bitmap_set_bit (loads, DECL_UID (sym));
+	}
+
+      FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_VDEF)
+	{
+	  tree sym = TREE_CODE (op) == SSA_NAME ? SSA_NAME_VAR (op) : op;
+	  if (stores == NULL)
+	    stores = BITMAP_ALLOC (NULL);
+	  bitmap_set_bit (stores, DECL_UID (sym));
+	}
+    }
+
+  /* If LOADS is different from BUF->LOADS, the affected
+     symbols need to be marked for renaming.  */
+  mark_difference_for_renaming (loads, buf->loads);
+
+  /* Similarly for STORES and BUF->STORES.  */
+  mark_difference_for_renaming (stores, buf->stores);
+
+  /* Mark all the naked GIMPLE register operands for renaming.  */
+  FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_DEF|SSA_OP_USE)
+    if (DECL_P (op))
+      mark_sym_for_renaming (op);
+
+  /* FIXME, need to add more finalizers here.  Cleanup EH info,
+     recompute invariants for address expressions, add
+     SSA replacement mappings, etc.  For instance, given
+     testsuite/gcc.c-torture/compile/pr16808.c, we fold a statement of
+     the form:
+
+	  # SMT.4_20 = VDEF <SMT.4_16>
+	  D.1576_11 = 1.0e+0;
+
+     So, the VDEF will disappear, but instead of marking SMT.4 for
+     renaming it would be far more efficient to establish a
+     replacement mapping that would replace every reference of
+     SMT.4_20 with SMT.4_16.  */
+
+  /* Free memory used by the buffer.  */
+  BITMAP_FREE (buf->loads);
+  BITMAP_FREE (buf->stores);
+  BITMAP_FREE (loads);
+  BITMAP_FREE (stores);
+  buf->stmt_p = NULL;
+  free (buf);
+}
+
+
+/* Discard the topmost change buffer from SCB_STACK.  This is useful
+   when the caller realized that it did not actually modified the
+   statement.  It avoids the expensive operand re-scan.  */
+
+void
+discard_stmt_changes (gimple *stmt_p)
+{
+  scb_t buf;
+  gimple stmt;
+  
+  /* It makes no sense to keep track of PHI nodes.  */
+  stmt = *stmt_p;
+  if (gimple_code (stmt) == GIMPLE_PHI)
+    return;
+
+  buf = VEC_pop (scb_t, scb_stack);
+  gcc_assert (stmt_p == buf->stmt_p);
+
+  /* Free memory used by the buffer.  */
+  BITMAP_FREE (buf->loads);
+  BITMAP_FREE (buf->stores);
+  buf->stmt_p = NULL;
+  free (buf);
+}