Add gcc-4.6. Synced to @180989

Change-Id: Ie3676586e1d8e3c8cd9f07d022f450d05fa08439
svn://gcc.gnu.org/svn/gcc/branches/google/gcc-4_6-mobile

1 files changed, 1357 insertions, 0 deletions

diff --git a/gcc-4.6/gcc/tree-ssa-operands.c b/gcc-4.6/gcc/tree-ssa-operands.c
new file mode 100644
index 000000000..d05f81491
--- /dev/null
+++ b/gcc-4.6/gcc/tree-ssa-operands.c
@@ -0,0 +1,1357 @@
+/* SSA operands management for trees.
+   Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
+   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 "tree-pretty-print.h"
+#include "gimple-pretty-print.h"
+#include "tree-flow.h"
+#include "tree-inline.h"
+#include "tree-pass.h"
+#include "ggc.h"
+#include "timevar.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'.  */
+
+/* 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)
+
+/* Operand is in a place where address-taken does not imply addressable.  */
+#define opf_non_addressable (1 << 3)
+
+/* Operand is in a place where opf_non_addressable does not apply.  */
+#define opf_not_non_addressable (1 << 4)
+
+/* 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;
+
+/* The built VDEF operand.  */
+static tree build_vdef;
+
+/* The built VUSE operand.  */
+static tree build_vuse;
+
+/* Bitmap obstack for our datastructures that needs to survive across
+   compilations of multiple functions.  */
+static bitmap_obstack operands_bitmap_obstack;
+
+static void get_expr_operands (gimple, tree *, int);
+
+/* Number of functions with initialized ssa_operands.  */
+static int n_initialized = 0;
+
+/* 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));
+}
+
+
+/*  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;
+}
+
+
+/* Create the VOP variable, an artificial global variable to act as a
+   representative of all of the virtual operands FUD chain.  */
+
+static void
+create_vop_var (void)
+{
+  tree global_var;
+
+  gcc_assert (cfun->gimple_df->vop == NULL_TREE);
+
+  global_var = build_decl (BUILTINS_LOCATION, VAR_DECL,
+			   get_identifier (".MEM"),
+			   void_type_node);
+  DECL_ARTIFICIAL (global_var) = 1;
+  TREE_READONLY (global_var) = 0;
+  DECL_EXTERNAL (global_var) = 1;
+  TREE_STATIC (global_var) = 1;
+  TREE_USED (global_var) = 1;
+  DECL_CONTEXT (global_var) = NULL_TREE;
+  TREE_THIS_VOLATILE (global_var) = 0;
+  TREE_ADDRESSABLE (global_var) = 0;
+
+  create_var_ann (global_var);
+  add_referenced_var (global_var);
+  cfun->gimple_df->vop = global_var;
+}
+
+/* These are the sizes of the operand memory buffer in bytes which gets
+   allocated each time more operands space is required.  The final value is
+   the amount that is allocated every time after that.
+   In 1k we can fit 25 use operands (or 63 def operands) on a host with
+   8 byte pointers, that would be 10 statements each with 1 def and 2
+   uses.  */
+
+#define OP_SIZE_INIT	0
+#define OP_SIZE_1	(1024 - sizeof (void *))
+#define OP_SIZE_2	(1024 * 4 - sizeof (void *))
+#define OP_SIZE_3	(1024 * 16 - sizeof (void *))
+
+/* 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_vuse = NULL_TREE;
+      build_vdef = NULL_TREE;
+      bitmap_obstack_initialize (&operands_bitmap_obstack);
+    }
+
+  gcc_assert (gimple_ssa_operands (cfun)->operand_memory == 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));
+  gimple_ssa_operands (cfun)->ssa_operand_mem_size = OP_SIZE_INIT;
+  create_vop_var ();
+}
+
+
+/* Dispose of anything required by the operand routines.  */
+
+void
+fini_ssa_operands (void)
+{
+  struct ssa_operand_memory_d *ptr;
+
+  if (!--n_initialized)
+    {
+      VEC_free (tree, heap, build_defs);
+      VEC_free (tree, heap, build_uses);
+      build_vdef = NULL_TREE;
+      build_vuse = NULL_TREE;
+    }
+
+  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);
+    }
+
+  gimple_ssa_operands (cfun)->ops_active = false;
+
+  if (!n_initialized)
+    bitmap_obstack_release (&operands_bitmap_obstack);
+
+  cfun->gimple_df->vop = NULL_TREE;
+
+  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 an operand of size SIZE.  */
+
+static inline void *
+ssa_operand_alloc (unsigned size)
+{
+  char *ptr;
+
+  gcc_assert (size == sizeof (struct use_optype_d)
+	      || size == sizeof (struct def_optype_d));
+
+  if (gimple_ssa_operands (cfun)->operand_memory_index + size
+      >= gimple_ssa_operands (cfun)->ssa_operand_mem_size)
+    {
+      struct ssa_operand_memory_d *ptr;
+
+      switch (gimple_ssa_operands (cfun)->ssa_operand_mem_size)
+	{
+	case OP_SIZE_INIT:
+	  gimple_ssa_operands (cfun)->ssa_operand_mem_size = OP_SIZE_1;
+	  break;
+	case OP_SIZE_1:
+	  gimple_ssa_operands (cfun)->ssa_operand_mem_size = OP_SIZE_2;
+	  break;
+	case OP_SIZE_2:
+	case OP_SIZE_3:
+	  gimple_ssa_operands (cfun)->ssa_operand_mem_size = OP_SIZE_3;
+	  break;
+	default:
+	  gcc_unreachable ();
+	}
+
+
+      ptr = ggc_alloc_ssa_operand_memory_d (sizeof (void *)
+                        + gimple_ssa_operands (cfun)->ssa_operand_mem_size);
+
+      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;
+}
+
+
+/* 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;
+}
+
+
+
+/* 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);
+
+  /* Pre-pend the vdef we may have built.  */
+  if (build_vdef != NULL_TREE)
+    {
+      tree oldvdef = gimple_vdef (stmt);
+      if (oldvdef
+	  && TREE_CODE (oldvdef) == SSA_NAME)
+	oldvdef = SSA_NAME_VAR (oldvdef);
+      if (oldvdef != build_vdef)
+	gimple_set_vdef (stmt, build_vdef);
+      VEC_safe_insert (tree, heap, build_defs, 0, (tree)gimple_vdef_ptr (stmt));
+      ++num;
+    }
+
+  new_list.next = NULL;
+  last = &new_list;
+
+  old_ops = gimple_def_ops (stmt);
+
+  new_i = 0;
+
+  /* Clear and unlink a no longer necessary VDEF.  */
+  if (build_vdef == NULL_TREE
+      && gimple_vdef (stmt) != NULL_TREE)
+    {
+      if (TREE_CODE (gimple_vdef (stmt)) == SSA_NAME)
+	{
+	  unlink_stmt_vdef (stmt);
+	  release_ssa_name (gimple_vdef (stmt));
+	}
+      gimple_set_vdef (stmt, NULL_TREE);
+    }
+
+  /* If we have a non-SSA_NAME VDEF, mark it for renaming.  */
+  if (gimple_vdef (stmt)
+      && TREE_CODE (gimple_vdef (stmt)) != SSA_NAME)
+    mark_sym_for_renaming (gimple_vdef (stmt));
+
+  /* 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);
+}
+
+
+/* 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;
+
+  /* Pre-pend the VUSE we may have built.  */
+  if (build_vuse != NULL_TREE)
+    {
+      tree oldvuse = gimple_vuse (stmt);
+      if (oldvuse
+	  && TREE_CODE (oldvuse) == SSA_NAME)
+	oldvuse = SSA_NAME_VAR (oldvuse);
+      if (oldvuse != (build_vuse != NULL_TREE
+		      ? build_vuse : build_vdef))
+	gimple_set_vuse (stmt, NULL_TREE);
+      VEC_safe_insert (tree, heap, build_uses, 0, (tree)gimple_vuse_ptr (stmt));
+    }
+
+  new_list.next = NULL;
+  last = &new_list;
+
+  old_ops = gimple_use_ops (stmt);
+
+  /* Clear a no longer necessary VUSE.  */
+  if (build_vuse == NULL_TREE
+      && gimple_vuse (stmt) != NULL_TREE)
+    gimple_set_vuse (stmt, NULL_TREE);
+
+  /* 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;
+    }
+
+  /* If we added a VUSE, make sure to set the operand if it is not already
+     present and mark it for renaming.  */
+  if (build_vuse != NULL_TREE
+      && gimple_vuse (stmt) == NULL_TREE)
+    {
+      gimple_set_vuse (stmt, gimple_vop (cfun));
+      mark_sym_for_renaming (gimple_vop (cfun));
+    }
+
+  /* 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);
+}
+
+
+/* Clear the in_list bits and empty the build array for VDEFs and
+   VUSEs.  */
+
+static inline void
+cleanup_build_arrays (void)
+{
+  build_vdef = NULL_TREE;
+  build_vuse = NULL_TREE;
+  VEC_truncate (tree, build_defs, 0);
+  VEC_truncate (tree, build_uses, 0);
+}
+
+
+/* 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);
+  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 (build_vuse == NULL_TREE);
+  gcc_assert (build_vdef == NULL_TREE);
+}
+
+
+/* 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)
+{
+  if (!optimize)
+    return;
+
+  gcc_assert ((build_vdef == NULL_TREE
+	       || build_vdef == var)
+	      && (build_vuse == NULL_TREE
+		  || build_vuse == var));
+
+  build_vdef = var;
+  build_vuse = var;
+}
+
+
+/* Add VAR to the set of variables that require a VUSE operator.  */
+
+static inline void
+append_vuse (tree var)
+{
+  if (!optimize)
+    return;
+
+  gcc_assert (build_vuse == NULL_TREE
+	      || build_vuse == var);
+
+  build_vuse = var;
+}
+
+/* Add virtual operands for STMT.  FLAGS is as in get_expr_operands.  */
+
+static void
+add_virtual_operand (gimple stmt ATTRIBUTE_UNUSED, int flags)
+{
+  /* Add virtual operands to the stmt, unless the caller has specifically
+     requested not to do that (used when adding operands inside an
+     ADDR_EXPR expression).  */
+  if (flags & opf_no_vops)
+    return;
+
+  gcc_assert (!is_gimple_debug (stmt));
+
+  if (flags & opf_def)
+    append_vdef (gimple_vop (cfun));
+  else
+    append_vuse (gimple_vop (cfun));
+}
+
+
+/* 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;
+
+  gcc_assert (SSA_VAR_P (*var_p));
+
+  var = *var_p;
+  sym = (TREE_CODE (var) == SSA_NAME ? SSA_NAME_VAR (var) : var);
+
+  /* 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 (stmt, flags);
+}
+
+/* Mark the base address of REF as having its address taken.
+   REF may be a single variable whose address has been taken or any
+   other valid GIMPLE memory reference (structure reference, array,
+   etc).  */
+
+static void
+mark_address_taken (tree ref)
+{
+  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)
+    {
+      if (DECL_P (var))
+	TREE_ADDRESSABLE (var) = 1;
+      else if (TREE_CODE (var) == MEM_REF
+	       && TREE_CODE (TREE_OPERAND (var, 0)) == ADDR_EXPR
+	       && DECL_P (TREE_OPERAND (TREE_OPERAND (var, 0), 0)))
+	TREE_ADDRESSABLE (TREE_OPERAND (TREE_OPERAND (var, 0), 0)) = 1;
+    }
+}
+
+
+/* A subroutine of get_expr_operands to handle MEM_REF.
+
+   STMT is the statement being processed, EXPR is the MEM_REF
+      that got us here.
+
+   FLAGS is as in get_expr_operands.
+
+   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,
+			   bool recurse_on_base)
+{
+  tree *pptr = &TREE_OPERAND (expr, 0);
+
+  if (TREE_THIS_VOLATILE (expr))
+    gimple_set_has_volatile_ops (stmt, true);
+
+  /* Add the VOP.  */
+  add_virtual_operand (stmt, flags);
+
+  /* If requested, add a USE operand for the base pointer.  */
+  if (recurse_on_base)
+    get_expr_operands (stmt, pptr,
+		       opf_non_addressable | opf_use
+		       | (flags & (opf_no_vops|opf_not_non_addressable)));
+}
+
+
+/* A subroutine of get_expr_operands to handle TARGET_MEM_REF.  */
+
+static void
+get_tmr_operands (gimple stmt, tree expr, int flags)
+{
+  if (TREE_THIS_VOLATILE (expr))
+    gimple_set_has_volatile_ops (stmt, true);
+
+  /* First record the real operands.  */
+  get_expr_operands (stmt, &TMR_BASE (expr), opf_use | (flags & opf_no_vops));
+  get_expr_operands (stmt, &TMR_INDEX (expr), opf_use | (flags & opf_no_vops));
+  get_expr_operands (stmt, &TMR_INDEX2 (expr), opf_use | (flags & opf_no_vops));
+
+  add_virtual_operand (stmt, flags);
+}
+
+
+/* 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_vops (gimple stmt)
+{
+  int call_flags = gimple_call_flags (stmt);
+
+  /* If aliases have been computed already, add VDEF or VUSE
+     operands for all the symbols that have been found to be
+     call-clobbered.  */
+  if (!(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_virtual_operand (stmt, opf_def);
+      else if (!(call_flags & ECF_CONST))
+	add_virtual_operand (stmt, opf_use);
+    }
+}
+
+
+/* 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)
+	mark_address_taken (TREE_VALUE (link));
+
+      get_expr_operands (stmt, &TREE_VALUE (link), opf_def | opf_not_non_addressable);
+    }
+
+  /* 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)
+	mark_address_taken (TREE_VALUE (link));
+
+      get_expr_operands (stmt, &TREE_VALUE (link), opf_not_non_addressable);
+    }
+
+  /* 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)
+	{
+	  add_virtual_operand (stmt, opf_def);
+	  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;
+  int uflags = opf_use;
+
+  if (expr == NULL)
+    return;
+
+  if (is_gimple_debug (stmt))
+    uflags |= (flags & opf_no_vops);
+
+  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).  */
+      if ((!(flags & opf_non_addressable)
+	   || (flags & opf_not_non_addressable))
+	  && !is_gimple_debug (stmt))
+	mark_address_taken (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 | opf_not_non_addressable);
+      return;
+
+    case SSA_NAME:
+     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 DEBUG_EXPR_DECL:
+      gcc_assert (gimple_debug_bind_p (stmt));
+      return;
+
+    case MEM_REF:
+      get_indirect_ref_operands (stmt, expr, flags, 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:
+      {
+	if (TREE_THIS_VOLATILE (expr))
+	  gimple_set_has_volatile_ops (stmt, true);
+
+	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), uflags);
+	  }
+	else if (code == ARRAY_REF || code == ARRAY_RANGE_REF)
+	  {
+            get_expr_operands (stmt, &TREE_OPERAND (expr, 1), uflags);
+            get_expr_operands (stmt, &TREE_OPERAND (expr, 2), uflags);
+            get_expr_operands (stmt, &TREE_OPERAND (expr, 3), uflags);
+	  }
+
+	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), uflags);
+      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), uflags);
+      get_expr_operands (stmt, &TREE_OPERAND (expr, 1), uflags);
+      get_expr_operands (stmt, &TREE_OPERAND (expr, 2), uflags);
+      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, uflags);
+
+	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:
+    case WIDEN_MULT_PLUS_EXPR:
+    case WIDEN_MULT_MINUS_EXPR:
+    case FMA_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 FUNCTION_DECL:
+    case LABEL_DECL:
+    case CONST_DECL:
+    case CASE_LABEL_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 if (is_gimple_debug (stmt))
+    {
+      if (gimple_debug_bind_p (stmt)
+	  && gimple_debug_bind_has_value_p (stmt))
+	get_expr_operands (stmt, gimple_debug_bind_get_value_ptr (stmt),
+			   opf_use | opf_no_vops);
+    }
+  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_vops (stmt);
+    }
+}
+
+
+/* Create an operands cache for STMT.  */
+
+static void
+build_ssa_operands (gimple stmt)
+{
+  /* Initially assume that the statement has no volatile operands.  */
+  gimple_set_has_volatile_ops (stmt, false);
+
+  start_ssa_stmt_operands ();
+  parse_ssa_operands (stmt);
+  finalize_ssa_stmt_operands (stmt);
+}
+
+
+/* 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;
+
+  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 (gimple_has_mem_ops (stmt))
+    {
+      gimple_set_vuse (stmt, NULL_TREE);
+      gimple_set_vdef (stmt, NULL_TREE);
+    }
+}
+
+
+/* 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);
+}
+
+
+/* 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;
+}
+
+
+/* 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.  */
+
+DEBUG_FUNCTION 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.  */
+
+DEBUG_FUNCTION void
+debug_immediate_uses (void)
+{
+  dump_immediate_uses (stderr);
+}
+
+
+/* Dump def-use edges on stderr.  */
+
+DEBUG_FUNCTION void
+debug_immediate_uses_for (tree var)
+{
+  dump_immediate_uses_for (stderr, var);
+}
+
+
+/* Unlink STMTs virtual definition from the IL by propagating its use.  */
+
+void
+unlink_stmt_vdef (gimple stmt)
+{
+  use_operand_p use_p;
+  imm_use_iterator iter;
+  gimple use_stmt;
+  tree vdef = gimple_vdef (stmt);
+
+  if (!vdef
+      || TREE_CODE (vdef) != SSA_NAME)
+    return;
+
+  FOR_EACH_IMM_USE_STMT (use_stmt, iter, gimple_vdef (stmt))
+    {
+      FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
+	SET_USE (use_p, gimple_vuse (stmt));
+    }
+
+  if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_vdef (stmt)))
+    SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_vuse (stmt)) = 1;
+}
+