gcc/tree-ssa-sccvn.c

/* SCC value numbering for trees
   Copyright (C) 2006-2021 Free Software Foundation, Inc.
   Contributed by Daniel Berlin <dan@dberlin.org>

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 "splay-tree.h"
#include "backend.h"
#include "rtl.h"
#include "tree.h"
#include "gimple.h"
#include "ssa.h"
#include "expmed.h"
#include "insn-config.h"
#include "memmodel.h"
#include "emit-rtl.h"
#include "cgraph.h"
#include "gimple-pretty-print.h"
#include "alias.h"
#include "fold-const.h"
#include "stor-layout.h"
#include "cfganal.h"
#include "tree-inline.h"
#include "internal-fn.h"
#include "gimple-fold.h"
#include "tree-eh.h"
#include "gimplify.h"
#include "flags.h"
#include "dojump.h"
#include "explow.h"
#include "calls.h"
#include "varasm.h"
#include "stmt.h"
#include "expr.h"
#include "tree-dfa.h"
#include "tree-ssa.h"
#include "dumpfile.h"
#include "cfgloop.h"
#include "tree-ssa-propagate.h"
#include "tree-cfg.h"
#include "domwalk.h"
#include "gimple-iterator.h"
#include "gimple-match.h"
#include "stringpool.h"
#include "attribs.h"
#include "tree-pass.h"
#include "statistics.h"
#include "langhooks.h"
#include "ipa-utils.h"
#include "dbgcnt.h"
#include "tree-cfgcleanup.h"
#include "tree-ssa-loop.h"
#include "tree-scalar-evolution.h"
#include "tree-ssa-loop-niter.h"
#include "builtins.h"
#include "fold-const-call.h"
#include "tree-ssa-sccvn.h"

/* This algorithm is based on the SCC algorithm presented by Keith
   Cooper and L. Taylor Simpson in "SCC-Based Value numbering"
   (http://citeseer.ist.psu.edu/41805.html).  In
   straight line code, it is equivalent to a regular hash based value
   numbering that is performed in reverse postorder.

   For code with cycles, there are two alternatives, both of which
   require keeping the hashtables separate from the actual list of
   value numbers for SSA names.

   1. Iterate value numbering in an RPO walk of the blocks, removing
   all the entries from the hashtable after each iteration (but
   keeping the SSA name->value number mapping between iterations).
   Iterate until it does not change.

   2. Perform value numbering as part of an SCC walk on the SSA graph,
   iterating only the cycles in the SSA graph until they do not change
   (using a separate, optimistic hashtable for value numbering the SCC
   operands).

   The second is not just faster in practice (because most SSA graph
   cycles do not involve all the variables in the graph), it also has
   some nice properties.

   One of these nice properties is that when we pop an SCC off the
   stack, we are guaranteed to have processed all the operands coming from
   *outside of that SCC*, so we do not need to do anything special to
   ensure they have value numbers.

   Another nice property is that the SCC walk is done as part of a DFS
   of the SSA graph, which makes it easy to perform combining and
   simplifying operations at the same time.

   The code below is deliberately written in a way that makes it easy
   to separate the SCC walk from the other work it does.

   In order to propagate constants through the code, we track which
   expressions contain constants, and use those while folding.  In
   theory, we could also track expressions whose value numbers are
   replaced, in case we end up folding based on expression
   identities.

   In order to value number memory, we assign value numbers to vuses.
   This enables us to note that, for example, stores to the same
   address of the same value from the same starting memory states are
   equivalent.
   TODO:

   1. We can iterate only the changing portions of the SCC's, but
   I have not seen an SCC big enough for this to be a win.
   2. If you differentiate between phi nodes for loops and phi nodes
   for if-then-else, you can properly consider phi nodes in different
   blocks for equivalence.
   3. We could value number vuses in more cases, particularly, whole
   structure copies.
*/

/* There's no BB_EXECUTABLE but we can use BB_VISITED.  */
#define BB_EXECUTABLE BB_VISITED

static vn_lookup_kind default_vn_walk_kind;

/* vn_nary_op hashtable helpers.  */

struct vn_nary_op_hasher : nofree_ptr_hash <vn_nary_op_s>
{
  typedef vn_nary_op_s *compare_type;
  static inline hashval_t hash (const vn_nary_op_s *);
  static inline bool equal (const vn_nary_op_s *, const vn_nary_op_s *);
};

/* Return the computed hashcode for nary operation P1.  */

inline hashval_t
vn_nary_op_hasher::hash (const vn_nary_op_s *vno1)
{
  return vno1->hashcode;
}

/* Compare nary operations P1 and P2 and return true if they are
   equivalent.  */

inline bool
vn_nary_op_hasher::equal (const vn_nary_op_s *vno1, const vn_nary_op_s *vno2)
{
  return vno1 == vno2 || vn_nary_op_eq (vno1, vno2);
}

typedef hash_table<vn_nary_op_hasher> vn_nary_op_table_type;
typedef vn_nary_op_table_type::iterator vn_nary_op_iterator_type;


/* vn_phi hashtable helpers.  */

static int
vn_phi_eq (const_vn_phi_t const vp1, const_vn_phi_t const vp2);

struct vn_phi_hasher : nofree_ptr_hash <vn_phi_s>
{ 
  static inline hashval_t hash (const vn_phi_s *);
  static inline bool equal (const vn_phi_s *, const vn_phi_s *);
};

/* Return the computed hashcode for phi operation P1.  */

inline hashval_t
vn_phi_hasher::hash (const vn_phi_s *vp1)
{
  return vp1->hashcode;
}

/* Compare two phi entries for equality, ignoring VN_TOP arguments.  */

inline bool
vn_phi_hasher::equal (const vn_phi_s *vp1, const vn_phi_s *vp2)
{
  return vp1 == vp2 || vn_phi_eq (vp1, vp2);
}

typedef hash_table<vn_phi_hasher> vn_phi_table_type;
typedef vn_phi_table_type::iterator vn_phi_iterator_type;


/* Compare two reference operands P1 and P2 for equality.  Return true if
   they are equal, and false otherwise.  */

static int
vn_reference_op_eq (const void *p1, const void *p2)
{
  const_vn_reference_op_t const vro1 = (const_vn_reference_op_t) p1;
  const_vn_reference_op_t const vro2 = (const_vn_reference_op_t) p2;

  return (vro1->opcode == vro2->opcode
	  /* We do not care for differences in type qualification.  */
	  && (vro1->type == vro2->type
	      || (vro1->type && vro2->type
		  && types_compatible_p (TYPE_MAIN_VARIANT (vro1->type),
					 TYPE_MAIN_VARIANT (vro2->type))))
	  && expressions_equal_p (vro1->op0, vro2->op0)
	  && expressions_equal_p (vro1->op1, vro2->op1)
	  && expressions_equal_p (vro1->op2, vro2->op2)
	  && (vro1->opcode != CALL_EXPR || vro1->clique == vro2->clique));
}

/* Free a reference operation structure VP.  */

static inline void
free_reference (vn_reference_s *vr)
{
  vr->operands.release ();
}


/* vn_reference hashtable helpers.  */

struct vn_reference_hasher : nofree_ptr_hash <vn_reference_s>
{
  static inline hashval_t hash (const vn_reference_s *);
  static inline bool equal (const vn_reference_s *, const vn_reference_s *);
};

/* Return the hashcode for a given reference operation P1.  */

inline hashval_t
vn_reference_hasher::hash (const vn_reference_s *vr1)
{
  return vr1->hashcode;
}

inline bool
vn_reference_hasher::equal (const vn_reference_s *v, const vn_reference_s *c)
{
  return v == c || vn_reference_eq (v, c);
}

typedef hash_table<vn_reference_hasher> vn_reference_table_type;
typedef vn_reference_table_type::iterator vn_reference_iterator_type;

/* Pretty-print OPS to OUTFILE.  */

void
print_vn_reference_ops (FILE *outfile, const vec<vn_reference_op_s> ops)
{
  vn_reference_op_t vro;
  unsigned int i;
  fprintf (outfile, "{");
  for (i = 0; ops.iterate (i, &vro); i++)
    {
      bool closebrace = false;
      if (vro->opcode != SSA_NAME
	  && TREE_CODE_CLASS (vro->opcode) != tcc_declaration)
	{
	  fprintf (outfile, "%s", get_tree_code_name (vro->opcode));
	  if (vro->op0 || vro->opcode == CALL_EXPR)
	    {
	      fprintf (outfile, "<");
	      closebrace = true;
	    }
	}
      if (vro->op0 || vro->opcode == CALL_EXPR)
	{
	  if (!vro->op0)
	    fprintf (outfile, internal_fn_name ((internal_fn)vro->clique));
	  else
	    print_generic_expr (outfile, vro->op0);
	  if (vro->op1)
	    {
	      fprintf (outfile, ",");
	      print_generic_expr (outfile, vro->op1);
	    }
	  if (vro->op2)
	    {
	      fprintf (outfile, ",");
	      print_generic_expr (outfile, vro->op2);
	    }
	}
      if (closebrace)
	fprintf (outfile, ">");
      if (i != ops.length () - 1)
	fprintf (outfile, ",");
    }
  fprintf (outfile, "}");
}

DEBUG_FUNCTION void
debug_vn_reference_ops (const vec<vn_reference_op_s> ops)
{
  print_vn_reference_ops (stderr, ops);
  fputc ('\n', stderr);
}

/* The set of VN hashtables.  */

typedef struct vn_tables_s
{
  vn_nary_op_table_type *nary;
  vn_phi_table_type *phis;
  vn_reference_table_type *references;
} *vn_tables_t;


/* vn_constant hashtable helpers.  */

struct vn_constant_hasher : free_ptr_hash <vn_constant_s>
{ 
  static inline hashval_t hash (const vn_constant_s *);
  static inline bool equal (const vn_constant_s *, const vn_constant_s *);
};

/* Hash table hash function for vn_constant_t.  */

inline hashval_t
vn_constant_hasher::hash (const vn_constant_s *vc1)
{
  return vc1->hashcode;
}

/* Hash table equality function for vn_constant_t.  */

inline bool
vn_constant_hasher::equal (const vn_constant_s *vc1, const vn_constant_s *vc2)
{
  if (vc1->hashcode != vc2->hashcode)
    return false;

  return vn_constant_eq_with_type (vc1->constant, vc2->constant);
}

static hash_table<vn_constant_hasher> *constant_to_value_id;


/* Obstack we allocate the vn-tables elements from.  */
static obstack vn_tables_obstack;
/* Special obstack we never unwind.  */
static obstack vn_tables_insert_obstack;

static vn_reference_t last_inserted_ref;
static vn_phi_t last_inserted_phi;
static vn_nary_op_t last_inserted_nary;
static vn_ssa_aux_t last_pushed_avail;

/* Valid hashtables storing information we have proven to be
   correct.  */
static vn_tables_t valid_info;


/* Valueization hook for simplify_replace_tree.  Valueize NAME if it is
   an SSA name, otherwise just return it.  */
tree (*vn_valueize) (tree);
static tree
vn_valueize_for_srt (tree t, void* context ATTRIBUTE_UNUSED)
{
  basic_block saved_vn_context_bb = vn_context_bb;
  /* Look for sth available at the definition block of the argument.
     This avoids inconsistencies between availability there which
     decides if the stmt can be removed and availability at the
     use site.  The SSA property ensures that things available
     at the definition are also available at uses.  */
  if (!SSA_NAME_IS_DEFAULT_DEF (t))
    vn_context_bb = gimple_bb (SSA_NAME_DEF_STMT (t));
  tree res = vn_valueize (t);
  vn_context_bb = saved_vn_context_bb;
  return res;
}


/* This represents the top of the VN lattice, which is the universal
   value.  */

tree VN_TOP;

/* Unique counter for our value ids.  */

static unsigned int next_value_id;
static int next_constant_value_id;


/* Table of vn_ssa_aux_t's, one per ssa_name.  The vn_ssa_aux_t objects
   are allocated on an obstack for locality reasons, and to free them
   without looping over the vec.  */

struct vn_ssa_aux_hasher : typed_noop_remove <vn_ssa_aux_t>
{
  typedef vn_ssa_aux_t value_type;
  typedef tree compare_type;
  static inline hashval_t hash (const value_type &);
  static inline bool equal (const value_type &, const compare_type &);
  static inline void mark_deleted (value_type &) {}
  static const bool empty_zero_p = true;
  static inline void mark_empty (value_type &e) { e = NULL; }
  static inline bool is_deleted (value_type &) { return false; }
  static inline bool is_empty (value_type &e) { return e == NULL; }
};

hashval_t
vn_ssa_aux_hasher::hash (const value_type &entry)
{
  return SSA_NAME_VERSION (entry->name);
}

bool
vn_ssa_aux_hasher::equal (const value_type &entry, const compare_type &name)
{
  return name == entry->name;
}

static hash_table<vn_ssa_aux_hasher> *vn_ssa_aux_hash;
typedef hash_table<vn_ssa_aux_hasher>::iterator vn_ssa_aux_iterator_type;
static struct obstack vn_ssa_aux_obstack;

static vn_nary_op_t vn_nary_op_insert_stmt (gimple *, tree);
static unsigned int vn_nary_length_from_stmt (gimple *);
static vn_nary_op_t alloc_vn_nary_op_noinit (unsigned int, obstack *);
static vn_nary_op_t vn_nary_op_insert_into (vn_nary_op_t,
					    vn_nary_op_table_type *, bool);
static void init_vn_nary_op_from_stmt (vn_nary_op_t, gassign *);
static void init_vn_nary_op_from_pieces (vn_nary_op_t, unsigned int,
					 enum tree_code, tree, tree *);
static tree vn_lookup_simplify_result (gimple_match_op *);
static vn_reference_t vn_reference_lookup_or_insert_for_pieces
	  (tree, alias_set_type, alias_set_type, tree,
	   vec<vn_reference_op_s, va_heap>, tree);

/* Return whether there is value numbering information for a given SSA name.  */

bool
has_VN_INFO (tree name)
{
  return vn_ssa_aux_hash->find_with_hash (name, SSA_NAME_VERSION (name));
}

vn_ssa_aux_t
VN_INFO (tree name)
{
  vn_ssa_aux_t *res
    = vn_ssa_aux_hash->find_slot_with_hash (name, SSA_NAME_VERSION (name),
					    INSERT);
  if (*res != NULL)
    return *res;

  vn_ssa_aux_t newinfo = *res = XOBNEW (&vn_ssa_aux_obstack, struct vn_ssa_aux);
  memset (newinfo, 0, sizeof (struct vn_ssa_aux));
  newinfo->name = name;
  newinfo->valnum = VN_TOP;
  /* We are using the visited flag to handle uses with defs not within the
     region being value-numbered.  */
  newinfo->visited = false;

  /* Given we create the VN_INFOs on-demand now we have to do initialization
     different than VN_TOP here.  */
  if (SSA_NAME_IS_DEFAULT_DEF (name))
    switch (TREE_CODE (SSA_NAME_VAR (name)))
      {
      case VAR_DECL:
        /* All undefined vars are VARYING.  */
        newinfo->valnum = name;
	newinfo->visited = true;
	break;

      case PARM_DECL:
	/* Parameters are VARYING but we can record a condition
	   if we know it is a non-NULL pointer.  */
	newinfo->visited = true;
	newinfo->valnum = name;
	if (POINTER_TYPE_P (TREE_TYPE (name))
	    && nonnull_arg_p (SSA_NAME_VAR (name)))
	  {
	    tree ops[2];
	    ops[0] = name;
	    ops[1] = build_int_cst (TREE_TYPE (name), 0);
	    vn_nary_op_t nary;
	    /* Allocate from non-unwinding stack.  */
	    nary = alloc_vn_nary_op_noinit (2, &vn_tables_insert_obstack);
	    init_vn_nary_op_from_pieces (nary, 2, NE_EXPR,
					 boolean_type_node, ops);
	    nary->predicated_values = 0;
	    nary->u.result = boolean_true_node;
	    vn_nary_op_insert_into (nary, valid_info->nary, true);
	    gcc_assert (nary->unwind_to == NULL);
	    /* Also do not link it into the undo chain.  */
	    last_inserted_nary = nary->next;
	    nary->next = (vn_nary_op_t)(void *)-1;
	    nary = alloc_vn_nary_op_noinit (2, &vn_tables_insert_obstack);
	    init_vn_nary_op_from_pieces (nary, 2, EQ_EXPR,
					 boolean_type_node, ops);
	    nary->predicated_values = 0;
	    nary->u.result = boolean_false_node;
	    vn_nary_op_insert_into (nary, valid_info->nary, true);
	    gcc_assert (nary->unwind_to == NULL);
	    last_inserted_nary = nary->next;
	    nary->next = (vn_nary_op_t)(void *)-1;
	    if (dump_file && (dump_flags & TDF_DETAILS))
	      {
		fprintf (dump_file, "Recording ");
		print_generic_expr (dump_file, name, TDF_SLIM);
		fprintf (dump_file, " != 0\n");
	      }
	  }
	break;

      case RESULT_DECL:
	/* If the result is passed by invisible reference the default
	   def is initialized, otherwise it's uninitialized.  Still
	   undefined is varying.  */
	newinfo->visited = true;
	newinfo->valnum = name;
	break;

      default:
	gcc_unreachable ();
      }
  return newinfo;
}

/* Return the SSA value of X.  */

inline tree
SSA_VAL (tree x, bool *visited = NULL)
{
  vn_ssa_aux_t tem = vn_ssa_aux_hash->find_with_hash (x, SSA_NAME_VERSION (x));
  if (visited)
    *visited = tem && tem->visited;
  return tem && tem->visited ? tem->valnum : x;
}

/* Return the SSA value of the VUSE x, supporting released VDEFs
   during elimination which will value-number the VDEF to the
   associated VUSE (but not substitute in the whole lattice).  */

static inline tree
vuse_ssa_val (tree x)
{
  if (!x)
    return NULL_TREE;

  do
    {
      x = SSA_VAL (x);
      gcc_assert (x != VN_TOP);
    }
  while (SSA_NAME_IN_FREE_LIST (x));

  return x;
}

/* Similar to the above but used as callback for walk_non_aliased_vuses
   and thus should stop at unvisited VUSE to not walk across region
   boundaries.  */

static tree
vuse_valueize (tree vuse)
{
  do
    {
      bool visited;
      vuse = SSA_VAL (vuse, &visited);
      if (!visited)
	return NULL_TREE;
      gcc_assert (vuse != VN_TOP);
    }
  while (SSA_NAME_IN_FREE_LIST (vuse));
  return vuse;
}


/* Return the vn_kind the expression computed by the stmt should be
   associated with.  */

enum vn_kind
vn_get_stmt_kind (gimple *stmt)
{
  switch (gimple_code (stmt))
    {
    case GIMPLE_CALL:
      return VN_REFERENCE;
    case GIMPLE_PHI:
      return VN_PHI;
    case GIMPLE_ASSIGN:
      {
	enum tree_code code = gimple_assign_rhs_code (stmt);
	tree rhs1 = gimple_assign_rhs1 (stmt);
	switch (get_gimple_rhs_class (code))
	  {
	  case GIMPLE_UNARY_RHS:
	  case GIMPLE_BINARY_RHS:
	  case GIMPLE_TERNARY_RHS:
	    return VN_NARY;
	  case GIMPLE_SINGLE_RHS:
	    switch (TREE_CODE_CLASS (code))
	      {
	      case tcc_reference:
		/* VOP-less references can go through unary case.  */
		if ((code == REALPART_EXPR
		     || code == IMAGPART_EXPR
		     || code == VIEW_CONVERT_EXPR
		     || code == BIT_FIELD_REF)
		    && (TREE_CODE (TREE_OPERAND (rhs1, 0)) == SSA_NAME
			|| is_gimple_min_invariant (TREE_OPERAND (rhs1, 0))))
		  return VN_NARY;

		/* Fallthrough.  */
	      case tcc_declaration:
		return VN_REFERENCE;

	      case tcc_constant:
		return VN_CONSTANT;

	      default:
		if (code == ADDR_EXPR)
		  return (is_gimple_min_invariant (rhs1)
			  ? VN_CONSTANT : VN_REFERENCE);
		else if (code == CONSTRUCTOR)
		  return VN_NARY;
		return VN_NONE;
	      }
	  default:
	    return VN_NONE;
	  }
      }
    default:
      return VN_NONE;
    }
}

/* Lookup a value id for CONSTANT and return it.  If it does not
   exist returns 0.  */

unsigned int
get_constant_value_id (tree constant)
{
  vn_constant_s **slot;
  struct vn_constant_s vc;

  vc.hashcode = vn_hash_constant_with_type (constant);
  vc.constant = constant;
  slot = constant_to_value_id->find_slot (&vc, NO_INSERT);
  if (slot)
    return (*slot)->value_id;
  return 0;
}

/* Lookup a value id for CONSTANT, and if it does not exist, create a
   new one and return it.  If it does exist, return it.  */

unsigned int
get_or_alloc_constant_value_id (tree constant)
{
  vn_constant_s **slot;
  struct vn_constant_s vc;
  vn_constant_t vcp;

  /* If the hashtable isn't initialized we're not running from PRE and thus
     do not need value-ids.  */
  if (!constant_to_value_id)
    return 0;

  vc.hashcode = vn_hash_constant_with_type (constant);
  vc.constant = constant;
  slot = constant_to_value_id->find_slot (&vc, INSERT);
  if (*slot)
    return (*slot)->value_id;

  vcp = XNEW (struct vn_constant_s);
  vcp->hashcode = vc.hashcode;
  vcp->constant = constant;
  vcp->value_id = get_next_constant_value_id ();
  *slot = vcp;
  return vcp->value_id;
}

/* Compute the hash for a reference operand VRO1.  */

static void
vn_reference_op_compute_hash (const vn_reference_op_t vro1, inchash::hash &hstate)
{
  hstate.add_int (vro1->opcode);
  if (vro1->opcode == CALL_EXPR && !vro1->op0)
    hstate.add_int (vro1->clique);
  if (vro1->op0)
    inchash::add_expr (vro1->op0, hstate);
  if (vro1->op1)
    inchash::add_expr (vro1->op1, hstate);
  if (vro1->op2)
    inchash::add_expr (vro1->op2, hstate);
}

/* Compute a hash for the reference operation VR1 and return it.  */

static hashval_t
vn_reference_compute_hash (const vn_reference_t vr1)
{
  inchash::hash hstate;
  hashval_t result;
  int i;
  vn_reference_op_t vro;
  poly_int64 off = -1;
  bool deref = false;

  FOR_EACH_VEC_ELT (vr1->operands, i, vro)
    {
      if (vro->opcode == MEM_REF)
	deref = true;
      else if (vro->opcode != ADDR_EXPR)
	deref = false;
      if (maybe_ne (vro->off, -1))
	{
	  if (known_eq (off, -1))
	    off = 0;
	  off += vro->off;
	}
      else
	{
	  if (maybe_ne (off, -1)
	      && maybe_ne (off, 0))
	    hstate.add_poly_int (off);
	  off = -1;
	  if (deref
	      && vro->opcode == ADDR_EXPR)
	    {
	      if (vro->op0)
		{
		  tree op = TREE_OPERAND (vro->op0, 0);
		  hstate.add_int (TREE_CODE (op));
		  inchash::add_expr (op, hstate);
		}
	    }
	  else
	    vn_reference_op_compute_hash (vro, hstate);
	}
    }
  result = hstate.end ();
  /* ??? We would ICE later if we hash instead of adding that in. */
  if (vr1->vuse)
    result += SSA_NAME_VERSION (vr1->vuse);

  return result;
}

/* Return true if reference operations VR1 and VR2 are equivalent.  This
   means they have the same set of operands and vuses.  */

bool
vn_reference_eq (const_vn_reference_t const vr1, const_vn_reference_t const vr2)
{
  unsigned i, j;

  /* Early out if this is not a hash collision.  */
  if (vr1->hashcode != vr2->hashcode)
    return false;

  /* The VOP needs to be the same.  */
  if (vr1->vuse != vr2->vuse)
    return false;

  /* If the operands are the same we are done.  */
  if (vr1->operands == vr2->operands)
    return true;

  if (!vr1->type || !vr2->type)
    {
      if (vr1->type != vr2->type)
	return false;
    }
  else if (vr1->type == vr2->type)
    ;
  else if (COMPLETE_TYPE_P (vr1->type) != COMPLETE_TYPE_P (vr2->type)
	   || (COMPLETE_TYPE_P (vr1->type)
	       && !expressions_equal_p (TYPE_SIZE (vr1->type),
					TYPE_SIZE (vr2->type))))
    return false;
  else if (vr1->operands[0].opcode == CALL_EXPR
	   && !types_compatible_p (vr1->type, vr2->type))
    return false;
  else if (INTEGRAL_TYPE_P (vr1->type)
	   && INTEGRAL_TYPE_P (vr2->type))
    {
      if (TYPE_PRECISION (vr1->type) != TYPE_PRECISION (vr2->type))
	return false;
    }
  else if (INTEGRAL_TYPE_P (vr1->type)
	   && (TYPE_PRECISION (vr1->type)
	       != TREE_INT_CST_LOW (TYPE_SIZE (vr1->type))))
    return false;
  else if (INTEGRAL_TYPE_P (vr2->type)
	   && (TYPE_PRECISION (vr2->type)
	       != TREE_INT_CST_LOW (TYPE_SIZE (vr2->type))))
    return false;

  i = 0;
  j = 0;
  do
    {
      poly_int64 off1 = 0, off2 = 0;
      vn_reference_op_t vro1, vro2;
      vn_reference_op_s tem1, tem2;
      bool deref1 = false, deref2 = false;
      bool reverse1 = false, reverse2 = false;
      for (; vr1->operands.iterate (i, &vro1); i++)
	{
	  if (vro1->opcode == MEM_REF)
	    deref1 = true;
	  /* Do not look through a storage order barrier.  */
	  else if (vro1->opcode == VIEW_CONVERT_EXPR && vro1->reverse)
	    return false;
	  reverse1 |= vro1->reverse;
	  if (known_eq (vro1->off, -1))
	    break;
	  off1 += vro1->off;
	}
      for (; vr2->operands.iterate (j, &vro2); j++)
	{
	  if (vro2->opcode == MEM_REF)
	    deref2 = true;
	  /* Do not look through a storage order barrier.  */
	  else if (vro2->opcode == VIEW_CONVERT_EXPR && vro2->reverse)
	    return false;
	  reverse2 |= vro2->reverse;
	  if (known_eq (vro2->off, -1))
	    break;
	  off2 += vro2->off;
	}
      if (maybe_ne (off1, off2) || reverse1 != reverse2)
	return false;
      if (deref1 && vro1->opcode == ADDR_EXPR)
	{
	  memset (&tem1, 0, sizeof (tem1));
	  tem1.op0 = TREE_OPERAND (vro1->op0, 0);
	  tem1.type = TREE_TYPE (tem1.op0);
	  tem1.opcode = TREE_CODE (tem1.op0);
	  vro1 = &tem1;
	  deref1 = false;
	}
      if (deref2 && vro2->opcode == ADDR_EXPR)
	{
	  memset (&tem2, 0, sizeof (tem2));
	  tem2.op0 = TREE_OPERAND (vro2->op0, 0);
	  tem2.type = TREE_TYPE (tem2.op0);
	  tem2.opcode = TREE_CODE (tem2.op0);
	  vro2 = &tem2;
	  deref2 = false;
	}
      if (deref1 != deref2)
	return false;
      if (!vn_reference_op_eq (vro1, vro2))
	return false;
      ++j;
      ++i;
    }
  while (vr1->operands.length () != i
	 || vr2->operands.length () != j);

  return true;
}

/* Copy the operations present in load/store REF into RESULT, a vector of
   vn_reference_op_s's.  */

static void
copy_reference_ops_from_ref (tree ref, vec<vn_reference_op_s> *result)
{
  /* For non-calls, store the information that makes up the address.  */
  tree orig = ref;
  while (ref)
    {
      vn_reference_op_s temp;

      memset (&temp, 0, sizeof (temp));
      temp.type = TREE_TYPE (ref);
      temp.opcode = TREE_CODE (ref);
      temp.off = -1;

      switch (temp.opcode)
	{
	case MODIFY_EXPR:
	  temp.op0 = TREE_OPERAND (ref, 1);
	  break;
	case WITH_SIZE_EXPR:
	  temp.op0 = TREE_OPERAND (ref, 1);
	  temp.off = 0;
	  break;
	case MEM_REF:
	  /* The base address gets its own vn_reference_op_s structure.  */
	  temp.op0 = TREE_OPERAND (ref, 1);
	  if (!mem_ref_offset (ref).to_shwi (&temp.off))
	    temp.off = -1;
	  temp.clique = MR_DEPENDENCE_CLIQUE (ref);
	  temp.base = MR_DEPENDENCE_BASE (ref);
	  temp.reverse = REF_REVERSE_STORAGE_ORDER (ref);
	  break;
	case TARGET_MEM_REF:
	  /* The base address gets its own vn_reference_op_s structure.  */
	  temp.op0 = TMR_INDEX (ref);
	  temp.op1 = TMR_STEP (ref);
	  temp.op2 = TMR_OFFSET (ref);
	  temp.clique = MR_DEPENDENCE_CLIQUE (ref);
	  temp.base = MR_DEPENDENCE_BASE (ref);
	  result->safe_push (temp);
	  memset (&temp, 0, sizeof (temp));
	  temp.type = NULL_TREE;
	  temp.opcode = ERROR_MARK;
	  temp.op0 = TMR_INDEX2 (ref);
	  temp.off = -1;
	  break;
	case BIT_FIELD_REF:
	  /* Record bits, position and storage order.  */
	  temp.op0 = TREE_OPERAND (ref, 1);
	  temp.op1 = TREE_OPERAND (ref, 2);
	  if (!multiple_p (bit_field_offset (ref), BITS_PER_UNIT, &temp.off))
	    temp.off = -1;
	  temp.reverse = REF_REVERSE_STORAGE_ORDER (ref);
	  break;
	case COMPONENT_REF:
	  /* The field decl is enough to unambiguously specify the field,
	     so use its type here.  */
	  temp.type = TREE_TYPE (TREE_OPERAND (ref, 1));
	  temp.op0 = TREE_OPERAND (ref, 1);
	  temp.op1 = TREE_OPERAND (ref, 2);
	  temp.reverse = (AGGREGATE_TYPE_P (TREE_TYPE (TREE_OPERAND (ref, 0)))
			  && TYPE_REVERSE_STORAGE_ORDER
			       (TREE_TYPE (TREE_OPERAND (ref, 0))));
	  {
	    tree this_offset = component_ref_field_offset (ref);
	    if (this_offset
		&& poly_int_tree_p (this_offset))
	      {
		tree bit_offset = DECL_FIELD_BIT_OFFSET (TREE_OPERAND (ref, 1));
		if (TREE_INT_CST_LOW (bit_offset) % BITS_PER_UNIT == 0)
		  {
		    poly_offset_int off
		      = (wi::to_poly_offset (this_offset)
			 + (wi::to_offset (bit_offset) >> LOG2_BITS_PER_UNIT));
		    /* Probibit value-numbering zero offset components
		       of addresses the same before the pass folding
		       __builtin_object_size had a chance to run.  */
		    if (TREE_CODE (orig) != ADDR_EXPR
			|| maybe_ne (off, 0)
			|| (cfun->curr_properties & PROP_objsz))
		      off.to_shwi (&temp.off);
		  }
	      }
	  }
	  break;
	case ARRAY_RANGE_REF:
	case ARRAY_REF:
	  {
	    tree eltype = TREE_TYPE (TREE_TYPE (TREE_OPERAND (ref, 0)));
	    /* Record index as operand.  */
	    temp.op0 = TREE_OPERAND (ref, 1);
	    /* Always record lower bounds and element size.  */
	    temp.op1 = array_ref_low_bound (ref);
	    /* But record element size in units of the type alignment.  */
	    temp.op2 = TREE_OPERAND (ref, 3);
	    temp.align = eltype->type_common.align;
	    if (! temp.op2)
	      temp.op2 = size_binop (EXACT_DIV_EXPR, TYPE_SIZE_UNIT (eltype),
				     size_int (TYPE_ALIGN_UNIT (eltype)));
	    if (poly_int_tree_p (temp.op0)
		&& poly_int_tree_p (temp.op1)
		&& TREE_CODE (temp.op2) == INTEGER_CST)
	      {
		poly_offset_int off = ((wi::to_poly_offset (temp.op0)
					- wi::to_poly_offset (temp.op1))
				       * wi::to_offset (temp.op2)
				       * vn_ref_op_align_unit (&temp));
		off.to_shwi (&temp.off);
	      }
	    temp.reverse = (AGGREGATE_TYPE_P (TREE_TYPE (TREE_OPERAND (ref, 0)))
			    && TYPE_REVERSE_STORAGE_ORDER
				 (TREE_TYPE (TREE_OPERAND (ref, 0))));
	  }
	  break;
	case VAR_DECL:
	  if (DECL_HARD_REGISTER (ref))
	    {
	      temp.op0 = ref;
	      break;
	    }
	  /* Fallthru.  */
	case PARM_DECL:
	case CONST_DECL:
	case RESULT_DECL:
	  /* Canonicalize decls to MEM[&decl] which is what we end up with
	     when valueizing MEM[ptr] with ptr = &decl.  */
	  temp.opcode = MEM_REF;
	  temp.op0 = build_int_cst (build_pointer_type (TREE_TYPE (ref)), 0);
	  temp.off = 0;
	  result->safe_push (temp);
	  temp.opcode = ADDR_EXPR;
	  temp.op0 = build1 (ADDR_EXPR, TREE_TYPE (temp.op0), ref);
	  temp.type = TREE_TYPE (temp.op0);
	  temp.off = -1;
	  break;
	case STRING_CST:
	case INTEGER_CST:
	case POLY_INT_CST:
	case COMPLEX_CST:
	case VECTOR_CST:
	case REAL_CST:
	case FIXED_CST:
	case CONSTRUCTOR:
	case SSA_NAME:
	  temp.op0 = ref;
	  break;
	case ADDR_EXPR:
	  if (is_gimple_min_invariant (ref))
	    {
	      temp.op0 = ref;
	      break;
	    }
	  break;
	  /* These are only interesting for their operands, their
	     existence, and their type.  They will never be the last
	     ref in the chain of references (IE they require an
	     operand), so we don't have to put anything
	     for op* as it will be handled by the iteration  */
	case REALPART_EXPR:
	  temp.off = 0;
	  break;
	case VIEW_CONVERT_EXPR:
	  temp.off = 0;
	  temp.reverse = storage_order_barrier_p (ref);
	  break;
	case IMAGPART_EXPR:
	  /* This is only interesting for its constant offset.  */
	  temp.off = TREE_INT_CST_LOW (TYPE_SIZE_UNIT (TREE_TYPE (ref)));
	  break;
	default:
	  gcc_unreachable ();
	}
      result->safe_push (temp);

      if (REFERENCE_CLASS_P (ref)
	  || TREE_CODE (ref) == MODIFY_EXPR
	  || TREE_CODE (ref) == WITH_SIZE_EXPR
	  || (TREE_CODE (ref) == ADDR_EXPR
	      && !is_gimple_min_invariant (ref)))
	ref = TREE_OPERAND (ref, 0);
      else
	ref = NULL_TREE;
    }
}

/* Build a alias-oracle reference abstraction in *REF from the vn_reference
   operands in *OPS, the reference alias set SET and the reference type TYPE.
   Return true if something useful was produced.  */

bool
ao_ref_init_from_vn_reference (ao_ref *ref,
			       alias_set_type set, alias_set_type base_set,
			       tree type, const vec<vn_reference_op_s> &ops)
{
  unsigned i;
  tree base = NULL_TREE;
  tree *op0_p = &base;
  poly_offset_int offset = 0;
  poly_offset_int max_size;
  poly_offset_int size = -1;
  tree size_tree = NULL_TREE;

  /* We don't handle calls.  */
  if (!type)
    return false;

  machine_mode mode = TYPE_MODE (type);
  if (mode == BLKmode)
    size_tree = TYPE_SIZE (type);
  else
    size = GET_MODE_BITSIZE (mode);
  if (size_tree != NULL_TREE
      && poly_int_tree_p (size_tree))
    size = wi::to_poly_offset (size_tree);

  /* Lower the final access size from the outermost expression.  */
  const_vn_reference_op_t cst_op = &ops[0];
  /* Cast away constness for the sake of the const-unsafe
     FOR_EACH_VEC_ELT().  */
  vn_reference_op_t op = const_cast<vn_reference_op_t>(cst_op);
  size_tree = NULL_TREE;
  if (op->opcode == COMPONENT_REF)
    size_tree = DECL_SIZE (op->op0);
  else if (op->opcode == BIT_FIELD_REF)
    size_tree = op->op0;
  if (size_tree != NULL_TREE
      && poly_int_tree_p (size_tree)
      && (!known_size_p (size)
	  || known_lt (wi::to_poly_offset (size_tree), size)))
    size = wi::to_poly_offset (size_tree);

  /* Initially, maxsize is the same as the accessed element size.
     In the following it will only grow (or become -1).  */
  max_size = size;

  /* Compute cumulative bit-offset for nested component-refs and array-refs,
     and find the ultimate containing object.  */
  FOR_EACH_VEC_ELT (ops, i, op)
    {
      switch (op->opcode)
	{
	/* These may be in the reference ops, but we cannot do anything
	   sensible with them here.  */
	case ADDR_EXPR:
	  /* Apart from ADDR_EXPR arguments to MEM_REF.  */
	  if (base != NULL_TREE
	      && TREE_CODE (base) == MEM_REF
	      && op->op0
	      && DECL_P (TREE_OPERAND (op->op0, 0)))
	    {
	      const_vn_reference_op_t pop = &ops[i-1];
	      base = TREE_OPERAND (op->op0, 0);
	      if (known_eq (pop->off, -1))
		{
		  max_size = -1;
		  offset = 0;
		}
	      else
		offset += pop->off * BITS_PER_UNIT;
	      op0_p = NULL;
	      break;
	    }
	  /* Fallthru.  */
	case CALL_EXPR:
	  return false;

	/* Record the base objects.  */
	case MEM_REF:
	  *op0_p = build2 (MEM_REF, op->type,
			   NULL_TREE, op->op0);
	  MR_DEPENDENCE_CLIQUE (*op0_p) = op->clique;
	  MR_DEPENDENCE_BASE (*op0_p) = op->base;
	  op0_p = &TREE_OPERAND (*op0_p, 0);
	  break;

	case VAR_DECL:
	case PARM_DECL:
	case RESULT_DECL:
	case SSA_NAME:
	  *op0_p = op->op0;
	  op0_p = NULL;
	  break;

	/* And now the usual component-reference style ops.  */
	case BIT_FIELD_REF:
	  offset += wi::to_poly_offset (op->op1);
	  break;

	case COMPONENT_REF:
	  {
	    tree field = op->op0;
	    /* We do not have a complete COMPONENT_REF tree here so we
	       cannot use component_ref_field_offset.  Do the interesting
	       parts manually.  */
	    tree this_offset = DECL_FIELD_OFFSET (field);

	    if (op->op1 || !poly_int_tree_p (this_offset))
	      max_size = -1;
	    else
	      {
		poly_offset_int woffset = (wi::to_poly_offset (this_offset)
					   << LOG2_BITS_PER_UNIT);
		woffset += wi::to_offset (DECL_FIELD_BIT_OFFSET (field));
		offset += woffset;
	      }
	    break;
	  }

	case ARRAY_RANGE_REF:
	case ARRAY_REF:
	  /* We recorded the lower bound and the element size.  */
	  if (!poly_int_tree_p (op->op0)
	      || !poly_int_tree_p (op->op1)
	      || TREE_CODE (op->op2) != INTEGER_CST)
	    max_size = -1;
	  else
	    {
	      poly_offset_int woffset
		= wi::sext (wi::to_poly_offset (op->op0)
			    - wi::to_poly_offset (op->op1),
			    TYPE_PRECISION (sizetype));
	      woffset *= wi::to_offset (op->op2) * vn_ref_op_align_unit (op);
	      woffset <<= LOG2_BITS_PER_UNIT;
	      offset += woffset;
	    }
	  break;

	case REALPART_EXPR:
	  break;

	case IMAGPART_EXPR:
	  offset += size;
	  break;

	case VIEW_CONVERT_EXPR:
	  break;

	case STRING_CST:
	case INTEGER_CST:
	case COMPLEX_CST:
	case VECTOR_CST:
	case REAL_CST:
	case CONSTRUCTOR:
	case CONST_DECL:
	  return false;

	default:
	  return false;
	}
    }

  if (base == NULL_TREE)
    return false;

  ref->ref = NULL_TREE;
  ref->base = base;
  ref->ref_alias_set = set;
  ref->base_alias_set = base_set;
  /* We discount volatiles from value-numbering elsewhere.  */
  ref->volatile_p = false;

  if (!size.to_shwi (&ref->size) || maybe_lt (ref->size, 0))
    {
      ref->offset = 0;
      ref->size = -1;
      ref->max_size = -1;
      return true;
    }

  if (!offset.to_shwi (&ref->offset))
    {
      ref->offset = 0;
      ref->max_size = -1;
      return true;
    }

  if (!max_size.to_shwi (&ref->max_size) || maybe_lt (ref->max_size, 0))
    ref->max_size = -1;

  return true;
}

/* Copy the operations present in load/store/call REF into RESULT, a vector of
   vn_reference_op_s's.  */

static void
copy_reference_ops_from_call (gcall *call,
			      vec<vn_reference_op_s> *result)
{
  vn_reference_op_s temp;
  unsigned i;
  tree lhs = gimple_call_lhs (call);
  int lr;

  /* If 2 calls have a different non-ssa lhs, vdef value numbers should be
     different.  By adding the lhs here in the vector, we ensure that the
     hashcode is different, guaranteeing a different value number.  */
  if (lhs && TREE_CODE (lhs) != SSA_NAME)
    {
      memset (&temp, 0, sizeof (temp));
      temp.opcode = MODIFY_EXPR;
      temp.type = TREE_TYPE (lhs);
      temp.op0 = lhs;
      temp.off = -1;
      result->safe_push (temp);
    }

  /* Copy the type, opcode, function, static chain and EH region, if any.  */
  memset (&temp, 0, sizeof (temp));
  temp.type = gimple_call_fntype (call);
  temp.opcode = CALL_EXPR;
  temp.op0 = gimple_call_fn (call);
  if (gimple_call_internal_p (call))
    temp.clique = gimple_call_internal_fn (call);
  temp.op1 = gimple_call_chain (call);
  if (stmt_could_throw_p (cfun, call) && (lr = lookup_stmt_eh_lp (call)) > 0)
    temp.op2 = size_int (lr);
  temp.off = -1;
  result->safe_push (temp);

  /* Copy the call arguments.  As they can be references as well,
     just chain them together.  */
  for (i = 0; i < gimple_call_num_args (call); ++i)
    {
      tree callarg = gimple_call_arg (call, i);
      copy_reference_ops_from_ref (callarg, result);
    }
}

/* Fold *& at position *I_P in a vn_reference_op_s vector *OPS.  Updates
   *I_P to point to the last element of the replacement.  */
static bool
vn_reference_fold_indirect (vec<vn_reference_op_s> *ops,
			    unsigned int *i_p)
{
  unsigned int i = *i_p;
  vn_reference_op_t op = &(*ops)[i];
  vn_reference_op_t mem_op = &(*ops)[i - 1];
  tree addr_base;
  poly_int64 addr_offset = 0;

  /* The only thing we have to do is from &OBJ.foo.bar add the offset
     from .foo.bar to the preceding MEM_REF offset and replace the
     address with &OBJ.  */
  addr_base = get_addr_base_and_unit_offset_1 (TREE_OPERAND (op->op0, 0),
					       &addr_offset, vn_valueize);
  gcc_checking_assert (addr_base && TREE_CODE (addr_base) != MEM_REF);
  if (addr_base != TREE_OPERAND (op->op0, 0))
    {
      poly_offset_int off
	= (poly_offset_int::from (wi::to_poly_wide (mem_op->op0),
				  SIGNED)
	   + addr_offset);
      mem_op->op0 = wide_int_to_tree (TREE_TYPE (mem_op->op0), off);
      op->op0 = build_fold_addr_expr (addr_base);
      if (tree_fits_shwi_p (mem_op->op0))
	mem_op->off = tree_to_shwi (mem_op->op0);
      else
	mem_op->off = -1;
      return true;
    }
  return false;
}

/* Fold *& at position *I_P in a vn_reference_op_s vector *OPS.  Updates
   *I_P to point to the last element of the replacement.  */
static bool
vn_reference_maybe_forwprop_address (vec<vn_reference_op_s> *ops,
				     unsigned int *i_p)
{
  bool changed = false;
  vn_reference_op_t op;

  do
    {
      unsigned int i = *i_p;
      op = &(*ops)[i];
      vn_reference_op_t mem_op = &(*ops)[i - 1];
      gimple *def_stmt;
      enum tree_code code;
      poly_offset_int off;

      def_stmt = SSA_NAME_DEF_STMT (op->op0);
      if (!is_gimple_assign (def_stmt))
	return changed;

      code = gimple_assign_rhs_code (def_stmt);
      if (code != ADDR_EXPR
	  && code != POINTER_PLUS_EXPR)
	return changed;

      off = poly_offset_int::from (wi::to_poly_wide (mem_op->op0), SIGNED);

      /* The only thing we have to do is from &OBJ.foo.bar add the offset
	 from .foo.bar to the preceding MEM_REF offset and replace the
	 address with &OBJ.  */
      if (code == ADDR_EXPR)
	{
	  tree addr, addr_base;
	  poly_int64 addr_offset;

	  addr = gimple_assign_rhs1 (def_stmt);
	  addr_base = get_addr_base_and_unit_offset_1 (TREE_OPERAND (addr, 0),
						       &addr_offset,
						       vn_valueize);
	  /* If that didn't work because the address isn't invariant propagate
	     the reference tree from the address operation in case the current
	     dereference isn't offsetted.  */
	  if (!addr_base
	      && *i_p == ops->length () - 1
	      && known_eq (off, 0)
	      /* This makes us disable this transform for PRE where the
		 reference ops might be also used for code insertion which
		 is invalid.  */
	      && default_vn_walk_kind == VN_WALKREWRITE)
	    {
	      auto_vec<vn_reference_op_s, 32> tem;
	      copy_reference_ops_from_ref (TREE_OPERAND (addr, 0), &tem);
	      /* Make sure to preserve TBAA info.  The only objects not
		 wrapped in MEM_REFs that can have their address taken are
		 STRING_CSTs.  */
	      if (tem.length () >= 2
		  && tem[tem.length () - 2].opcode == MEM_REF)
		{
		  vn_reference_op_t new_mem_op = &tem[tem.length () - 2];
		  new_mem_op->op0
		      = wide_int_to_tree (TREE_TYPE (mem_op->op0),
					  wi::to_poly_wide (new_mem_op->op0));
		}
	      else
		gcc_assert (tem.last ().opcode == STRING_CST);
	      ops->pop ();
	      ops->pop ();
	      ops->safe_splice (tem);
	      --*i_p;
	      return true;
	    }
	  if (!addr_base
	      || TREE_CODE (addr_base) != MEM_REF
	      || (TREE_CODE (TREE_OPERAND (addr_base, 0)) == SSA_NAME
		  && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (TREE_OPERAND (addr_base,
								    0))))
	    return changed;

	  off += addr_offset;
	  off += mem_ref_offset (addr_base);
	  op->op0 = TREE_OPERAND (addr_base, 0);
	}
      else
	{
	  tree ptr, ptroff;
	  ptr = gimple_assign_rhs1 (def_stmt);
	  ptroff = gimple_assign_rhs2 (def_stmt);
	  if (TREE_CODE (ptr) != SSA_NAME
	      || SSA_NAME_OCCURS_IN_ABNORMAL_PHI (ptr)
	      /* Make sure to not endlessly recurse.
		 See gcc.dg/tree-ssa/20040408-1.c for an example.  Can easily
		 happen when we value-number a PHI to its backedge value.  */
	      || SSA_VAL (ptr) == op->op0
	      || !poly_int_tree_p (ptroff))
	    return changed;

	  off += wi::to_poly_offset (ptroff);
	  op->op0 = ptr;
	}

      mem_op->op0 = wide_int_to_tree (TREE_TYPE (mem_op->op0), off);
      if (tree_fits_shwi_p (mem_op->op0))
	mem_op->off = tree_to_shwi (mem_op->op0);
      else
	mem_op->off = -1;
      /* ???  Can end up with endless recursion here!?
	 gcc.c-torture/execute/strcmp-1.c  */
      if (TREE_CODE (op->op0) == SSA_NAME)
	op->op0 = SSA_VAL (op->op0);
      if (TREE_CODE (op->op0) != SSA_NAME)
	op->opcode = TREE_CODE (op->op0);

      changed = true;
    }
  /* Tail-recurse.  */
  while (TREE_CODE (op->op0) == SSA_NAME);

  /* Fold a remaining *&.  */
  if (TREE_CODE (op->op0) == ADDR_EXPR)
    vn_reference_fold_indirect (ops, i_p);

  return changed;
}

/* Optimize the reference REF to a constant if possible or return
   NULL_TREE if not.  */

tree
fully_constant_vn_reference_p (vn_reference_t ref)
{
  vec<vn_reference_op_s> operands = ref->operands;
  vn_reference_op_t op;

  /* Try to simplify the translated expression if it is
     a call to a builtin function with at most two arguments.  */
  op = &operands[0];
  if (op->opcode == CALL_EXPR
      && (!op->op0
	  || (TREE_CODE (op->op0) == ADDR_EXPR
	      && TREE_CODE (TREE_OPERAND (op->op0, 0)) == FUNCTION_DECL
	      && fndecl_built_in_p (TREE_OPERAND (op->op0, 0),
				    BUILT_IN_NORMAL)))
      && operands.length () >= 2
      && operands.length () <= 3)
    {
      vn_reference_op_t arg0, arg1 = NULL;
      bool anyconst = false;
      arg0 = &operands[1];
      if (operands.length () > 2)
	arg1 = &operands[2];
      if (TREE_CODE_CLASS (arg0->opcode) == tcc_constant
	  || (arg0->opcode == ADDR_EXPR
	      && is_gimple_min_invariant (arg0->op0)))
	anyconst = true;
      if (arg1
	  && (TREE_CODE_CLASS (arg1->opcode) == tcc_constant
	      || (arg1->opcode == ADDR_EXPR
		  && is_gimple_min_invariant (arg1->op0))))
	anyconst = true;
      if (anyconst)
	{
	  combined_fn fn;
	  if (op->op0)
	    fn = as_combined_fn (DECL_FUNCTION_CODE
					(TREE_OPERAND (op->op0, 0)));
	  else
	    fn = as_combined_fn ((internal_fn) op->clique);
	  tree folded;
	  if (arg1)
	    folded = fold_const_call (fn, ref->type, arg0->op0, arg1->op0);
	  else
	    folded = fold_const_call (fn, ref->type, arg0->op0);
	  if (folded
	      && is_gimple_min_invariant (folded))
	    return folded;
	}
    }

  /* Simplify reads from constants or constant initializers.  */
  else if (BITS_PER_UNIT == 8
	   && ref->type
	   && COMPLETE_TYPE_P (ref->type)
	   && is_gimple_reg_type (ref->type))
    {
      poly_int64 off = 0;
      HOST_WIDE_INT size;
      if (INTEGRAL_TYPE_P (ref->type))
	size = TYPE_PRECISION (ref->type);
      else if (tree_fits_shwi_p (TYPE_SIZE (ref->type)))
	size = tree_to_shwi (TYPE_SIZE (ref->type));
      else
	return NULL_TREE;
      if (size % BITS_PER_UNIT != 0
	  || size > MAX_BITSIZE_MODE_ANY_MODE)
	return NULL_TREE;
      size /= BITS_PER_UNIT;
      unsigned i;
      for (i = 0; i < operands.length (); ++i)
	{
	  if (TREE_CODE_CLASS (operands[i].opcode) == tcc_constant)
	    {
	      ++i;
	      break;
	    }
	  if (known_eq (operands[i].off, -1))
	    return NULL_TREE;
	  off += operands[i].off;
	  if (operands[i].opcode == MEM_REF)
	    {
	      ++i;
	      break;
	    }
	}
      vn_reference_op_t base = &operands[--i];
      tree ctor = error_mark_node;
      tree decl = NULL_TREE;
      if (TREE_CODE_CLASS (base->opcode) == tcc_constant)
	ctor = base->op0;
      else if (base->opcode == MEM_REF
	       && base[1].opcode == ADDR_EXPR
	       && (TREE_CODE (TREE_OPERAND (base[1].op0, 0)) == VAR_DECL
		   || TREE_CODE (TREE_OPERAND (base[1].op0, 0)) == CONST_DECL
		   || TREE_CODE (TREE_OPERAND (base[1].op0, 0)) == STRING_CST))
	{
	  decl = TREE_OPERAND (base[1].op0, 0);
	  if (TREE_CODE (decl) == STRING_CST)
	    ctor = decl;
	  else
	    ctor = ctor_for_folding (decl);
	}
      if (ctor == NULL_TREE)
	return build_zero_cst (ref->type);
      else if (ctor != error_mark_node)
	{
	  HOST_WIDE_INT const_off;
	  if (decl)
	    {
	      tree res = fold_ctor_reference (ref->type, ctor,
					      off * BITS_PER_UNIT,
					      size * BITS_PER_UNIT, decl);
	      if (res)
		{
		  STRIP_USELESS_TYPE_CONVERSION (res);
		  if (is_gimple_min_invariant (res))
		    return res;
		}
	    }
	  else if (off.is_constant (&const_off))
	    {
	      unsigned char buf[MAX_BITSIZE_MODE_ANY_MODE / BITS_PER_UNIT];
	      int len = native_encode_expr (ctor, buf, size, const_off);
	      if (len > 0)
		return native_interpret_expr (ref->type, buf, len);
	    }
	}
    }

  return NULL_TREE;
}

/* Return true if OPS contain a storage order barrier.  */

static bool
contains_storage_order_barrier_p (vec<vn_reference_op_s> ops)
{
  vn_reference_op_t op;
  unsigned i;

  FOR_EACH_VEC_ELT (ops, i, op)
    if (op->opcode == VIEW_CONVERT_EXPR && op->reverse)
      return true;

  return false;
}

/* Return true if OPS represent an access with reverse storage order.  */

static bool
reverse_storage_order_for_component_p (vec<vn_reference_op_s> ops)
{
  unsigned i = 0;
  if (ops[i].opcode == REALPART_EXPR || ops[i].opcode == IMAGPART_EXPR)
    ++i;
  switch (ops[i].opcode)
    {
    case ARRAY_REF:
    case COMPONENT_REF:
    case BIT_FIELD_REF:
    case MEM_REF:
      return ops[i].reverse;
    default:
      return false;
    }
}

/* Transform any SSA_NAME's in a vector of vn_reference_op_s
   structures into their value numbers.  This is done in-place, and
   the vector passed in is returned.  *VALUEIZED_ANYTHING will specify
   whether any operands were valueized.  */

static void
valueize_refs_1 (vec<vn_reference_op_s> *orig, bool *valueized_anything,
		 bool with_avail = false)
{
  vn_reference_op_t vro;
  unsigned int i;

  *valueized_anything = false;

  FOR_EACH_VEC_ELT (*orig, i, vro)
    {
      if (vro->opcode == SSA_NAME
	  || (vro->op0 && TREE_CODE (vro->op0) == SSA_NAME))
	{
	  tree tem = with_avail ? vn_valueize (vro->op0) : SSA_VAL (vro->op0);
	  if (tem != vro->op0)
	    {
	      *valueized_anything = true;
	      vro->op0 = tem;
	    }
	  /* If it transforms from an SSA_NAME to a constant, update
	     the opcode.  */
	  if (TREE_CODE (vro->op0) != SSA_NAME && vro->opcode == SSA_NAME)
	    vro->opcode = TREE_CODE (vro->op0);
	}
      if (vro->op1 && TREE_CODE (vro->op1) == SSA_NAME)
	{
	  tree tem = with_avail ? vn_valueize (vro->op1) : SSA_VAL (vro->op1);
	  if (tem != vro->op1)
	    {
	      *valueized_anything = true;
	      vro->op1 = tem;
	    }
	}
      if (vro->op2 && TREE_CODE (vro->op2) == SSA_NAME)
	{
	  tree tem = with_avail ? vn_valueize (vro->op2) : SSA_VAL (vro->op2);
	  if (tem != vro->op2)
	    {
	      *valueized_anything = true;
	      vro->op2 = tem;
	    }
	}
      /* If it transforms from an SSA_NAME to an address, fold with
	 a preceding indirect reference.  */
      if (i > 0
	  && vro->op0
	  && TREE_CODE (vro->op0) == ADDR_EXPR
	  && (*orig)[i - 1].opcode == MEM_REF)
	{
	  if (vn_reference_fold_indirect (orig, &i))
	    *valueized_anything = true;
	}
      else if (i > 0
	       && vro->opcode == SSA_NAME
	       && (*orig)[i - 1].opcode == MEM_REF)
	{
	  if (vn_reference_maybe_forwprop_address (orig, &i))
	    *valueized_anything = true;
	}
      /* If it transforms a non-constant ARRAY_REF into a constant
	 one, adjust the constant offset.  */
      else if (vro->opcode == ARRAY_REF
	       && known_eq (vro->off, -1)
	       && poly_int_tree_p (vro->op0)
	       && poly_int_tree_p (vro->op1)
	       && TREE_CODE (vro->op2) == INTEGER_CST)
	{
	  poly_offset_int off = ((wi::to_poly_offset (vro->op0)
				  - wi::to_poly_offset (vro->op1))
				 * wi::to_offset (vro->op2)
				 * vn_ref_op_align_unit (vro));
	  off.to_shwi (&vro->off);
	}
    }
}

static void
valueize_refs (vec<vn_reference_op_s> *orig)
{
  bool tem;
  valueize_refs_1 (orig, &tem);
}

static vec<vn_reference_op_s> shared_lookup_references;

/* Create a vector of vn_reference_op_s structures from REF, a
   REFERENCE_CLASS_P tree.  The vector is shared among all callers of
   this function.  *VALUEIZED_ANYTHING will specify whether any
   operands were valueized.  */

static vec<vn_reference_op_s> 
valueize_shared_reference_ops_from_ref (tree ref, bool *valueized_anything)
{
  if (!ref)
    return vNULL;
  shared_lookup_references.truncate (0);
  copy_reference_ops_from_ref (ref, &shared_lookup_references);
  valueize_refs_1 (&shared_lookup_references, valueized_anything);
  return shared_lookup_references;
}

/* Create a vector of vn_reference_op_s structures from CALL, a
   call statement.  The vector is shared among all callers of
   this function.  */

static vec<vn_reference_op_s> 
valueize_shared_reference_ops_from_call (gcall *call)
{
  if (!call)
    return vNULL;
  shared_lookup_references.truncate (0);
  copy_reference_ops_from_call (call, &shared_lookup_references);
  valueize_refs (&shared_lookup_references);
  return shared_lookup_references;
}

/* Lookup a SCCVN reference operation VR in the current hash table.
   Returns the resulting value number if it exists in the hash table,
   NULL_TREE otherwise.  VNRESULT will be filled in with the actual
   vn_reference_t stored in the hashtable if something is found.  */

static tree
vn_reference_lookup_1 (vn_reference_t vr, vn_reference_t *vnresult)
{
  vn_reference_s **slot;
  hashval_t hash;

  hash = vr->hashcode;
  slot = valid_info->references->find_slot_with_hash (vr, hash, NO_INSERT);
  if (slot)
    {
      if (vnresult)
	*vnresult = (vn_reference_t)*slot;
      return ((vn_reference_t)*slot)->result;
    }

  return NULL_TREE;
}


/* Partial definition tracking support.  */

struct pd_range
{
  HOST_WIDE_INT offset;
  HOST_WIDE_INT size;
};

struct pd_data
{
  tree rhs;
  HOST_WIDE_INT offset;
  HOST_WIDE_INT size;
};

/* Context for alias walking.  */

struct vn_walk_cb_data
{
  vn_walk_cb_data (vn_reference_t vr_, tree orig_ref_, tree *last_vuse_ptr_,
		   vn_lookup_kind vn_walk_kind_, bool tbaa_p_, tree mask_)
    : vr (vr_), last_vuse_ptr (last_vuse_ptr_), last_vuse (NULL_TREE),
      mask (mask_), masked_result (NULL_TREE), vn_walk_kind (vn_walk_kind_),
      tbaa_p (tbaa_p_), saved_operands (vNULL), first_set (-2),
      first_base_set (-2), known_ranges (NULL)
  {
    if (!last_vuse_ptr)
      last_vuse_ptr = &last_vuse;
    ao_ref_init (&orig_ref, orig_ref_);
    if (mask)
      {
	wide_int w = wi::to_wide (mask);
	unsigned int pos = 0, prec = w.get_precision ();
	pd_data pd;
	pd.rhs = build_constructor (NULL_TREE, NULL);
	/* When bitwise and with a constant is done on a memory load,
	   we don't really need all the bits to be defined or defined
	   to constants, we don't really care what is in the position
	   corresponding to 0 bits in the mask.
	   So, push the ranges of those 0 bits in the mask as artificial
	   zero stores and let the partial def handling code do the
	   rest.  */
	while (pos < prec)
	  {
	    int tz = wi::ctz (w);
	    if (pos + tz > prec)
	      tz = prec - pos;
	    if (tz)
	      {
		if (BYTES_BIG_ENDIAN)
		  pd.offset = prec - pos - tz;
		else
		  pd.offset = pos;
		pd.size = tz;
		void *r = push_partial_def (pd, 0, 0, 0, prec);
		gcc_assert (r == NULL_TREE);
	      }
	    pos += tz;
	    if (pos == prec)
	      break;
	    w = wi::lrshift (w, tz);
	    tz = wi::ctz (wi::bit_not (w));
	    if (pos + tz > prec)
	      tz = prec - pos;
	    pos += tz;
	    w = wi::lrshift (w, tz);
	  }
      }
  }
  ~vn_walk_cb_data ();
  void *finish (alias_set_type, alias_set_type, tree);
  void *push_partial_def (pd_data pd,
			  alias_set_type, alias_set_type, HOST_WIDE_INT,
			  HOST_WIDE_INT);

  vn_reference_t vr;
  ao_ref orig_ref;
  tree *last_vuse_ptr;
  tree last_vuse;
  tree mask;
  tree masked_result;
  vn_lookup_kind vn_walk_kind;
  bool tbaa_p;
  vec<vn_reference_op_s> saved_operands;

  /* The VDEFs of partial defs we come along.  */
  auto_vec<pd_data, 2> partial_defs;
  /* The first defs range to avoid splay tree setup in most cases.  */
  pd_range first_range;
  alias_set_type first_set;
  alias_set_type first_base_set;
  splay_tree known_ranges;
  obstack ranges_obstack;
};

vn_walk_cb_data::~vn_walk_cb_data ()
{
  if (known_ranges)
    {
      splay_tree_delete (known_ranges);
      obstack_free (&ranges_obstack, NULL);
    }
  saved_operands.release ();
}

void *
vn_walk_cb_data::finish (alias_set_type set, alias_set_type base_set, tree val)
{
  if (first_set != -2)
    {
      set = first_set;
      base_set = first_base_set;
    }
  if (mask)
    {
      masked_result = val;
      return (void *) -1;
    }
  vec<vn_reference_op_s> &operands
    = saved_operands.exists () ? saved_operands : vr->operands;
  return vn_reference_lookup_or_insert_for_pieces (last_vuse, set, base_set,
						   vr->type, operands, val);
}

/* pd_range splay-tree helpers.  */

static int
pd_range_compare (splay_tree_key offset1p, splay_tree_key offset2p)
{
  HOST_WIDE_INT offset1 = *(HOST_WIDE_INT *)offset1p;
  HOST_WIDE_INT offset2 = *(HOST_WIDE_INT *)offset2p;
  if (offset1 < offset2)
    return -1;
  else if (offset1 > offset2)
    return 1;
  return 0;
}

static void *
pd_tree_alloc (int size, void *data_)
{
  vn_walk_cb_data *data = (vn_walk_cb_data *)data_;
  return obstack_alloc (&data->ranges_obstack, size);
}

static void
pd_tree_dealloc (void *, void *)
{
}

/* Push PD to the vector of partial definitions returning a
   value when we are ready to combine things with VUSE, SET and MAXSIZEI,
   NULL when we want to continue looking for partial defs or -1
   on failure.  */

void *
vn_walk_cb_data::push_partial_def (pd_data pd,
				   alias_set_type set, alias_set_type base_set,
				   HOST_WIDE_INT offseti,
				   HOST_WIDE_INT maxsizei)
{
  const HOST_WIDE_INT bufsize = 64;
  /* We're using a fixed buffer for encoding so fail early if the object
     we want to interpret is bigger.  */
  if (maxsizei > bufsize * BITS_PER_UNIT
      || CHAR_BIT != 8
      || BITS_PER_UNIT != 8
      /* Not prepared to handle PDP endian.  */
      || BYTES_BIG_ENDIAN != WORDS_BIG_ENDIAN)
    return (void *)-1;

  /* Turn too large constant stores into non-constant stores.  */
  if (CONSTANT_CLASS_P (pd.rhs) && pd.size > bufsize * BITS_PER_UNIT)
    pd.rhs = error_mark_node;

  /* And for non-constant or CONSTRUCTOR stores shrink them to only keep at
     most a partial byte before and/or after the region.  */
  if (!CONSTANT_CLASS_P (pd.rhs))
    {
      if (pd.offset < offseti)
	{
	  HOST_WIDE_INT o = ROUND_DOWN (offseti - pd.offset, BITS_PER_UNIT);
	  gcc_assert (pd.size > o);
	  pd.size -= o;
	  pd.offset += o;
	}
      if (pd.size > maxsizei)
	pd.size = maxsizei + ((pd.size - maxsizei) % BITS_PER_UNIT);
    }

  pd.offset -= offseti;

  bool pd_constant_p = (TREE_CODE (pd.rhs) == CONSTRUCTOR
			|| CONSTANT_CLASS_P (pd.rhs));
  if (partial_defs.is_empty ())
    {
      /* If we get a clobber upfront, fail.  */
      if (TREE_CLOBBER_P (pd.rhs))
	return (void *)-1;
      if (!pd_constant_p)
	return (void *)-1;
      partial_defs.safe_push (pd);
      first_range.offset = pd.offset;
      first_range.size = pd.size;
      first_set = set;
      first_base_set = base_set;
      last_vuse_ptr = NULL;
      /* Continue looking for partial defs.  */
      return NULL;
    }

  if (!known_ranges)
    {
      /* ???  Optimize the case where the 2nd partial def completes things.  */
      gcc_obstack_init (&ranges_obstack);
      known_ranges = splay_tree_new_with_allocator (pd_range_compare, 0, 0,
						    pd_tree_alloc,
						    pd_tree_dealloc, this);
      splay_tree_insert (known_ranges,
			 (splay_tree_key)&first_range.offset,
			 (splay_tree_value)&first_range);
    }

  pd_range newr = { pd.offset, pd.size };
  splay_tree_node n;
  pd_range *r;
  /* Lookup the predecessor of offset + 1 and see if we need to merge.  */
  HOST_WIDE_INT loffset = newr.offset + 1;
  if ((n = splay_tree_predecessor (known_ranges, (splay_tree_key)&loffset))
      && ((r = (pd_range *)n->value), true)
      && ranges_known_overlap_p (r->offset, r->size + 1,
				 newr.offset, newr.size))
    {
      /* Ignore partial defs already covered.  Here we also drop shadowed
         clobbers arriving here at the floor.  */
      if (known_subrange_p (newr.offset, newr.size, r->offset, r->size))
	return NULL;
      r->size = MAX (r->offset + r->size, newr.offset + newr.size) - r->offset;
    }
  else
    {
      /* newr.offset wasn't covered yet, insert the range.  */
      r = XOBNEW (&ranges_obstack, pd_range);
      *r = newr;
      splay_tree_insert (known_ranges, (splay_tree_key)&r->offset,
			 (splay_tree_value)r);
    }
  /* Merge r which now contains newr and is a member of the splay tree with
     adjacent overlapping ranges.  */
  pd_range *rafter;
  while ((n = splay_tree_successor (known_ranges, (splay_tree_key)&r->offset))
	 && ((rafter = (pd_range *)n->value), true)
	 && ranges_known_overlap_p (r->offset, r->size + 1,
				    rafter->offset, rafter->size))
    {
      r->size = MAX (r->offset + r->size,
		     rafter->offset + rafter->size) - r->offset;
      splay_tree_remove (known_ranges, (splay_tree_key)&rafter->offset);
    }
  /* If we get a clobber, fail.  */
  if (TREE_CLOBBER_P (pd.rhs))
    return (void *)-1;
  /* Non-constants are OK as long as they are shadowed by a constant.  */
  if (!pd_constant_p)
    return (void *)-1;
  partial_defs.safe_push (pd);

  /* Now we have merged newr into the range tree.  When we have covered
     [offseti, sizei] then the tree will contain exactly one node which has
     the desired properties and it will be 'r'.  */
  if (!known_subrange_p (0, maxsizei, r->offset, r->size))
    /* Continue looking for partial defs.  */
    return NULL;

  /* Now simply native encode all partial defs in reverse order.  */
  unsigned ndefs = partial_defs.length ();
  /* We support up to 512-bit values (for V8DFmode).  */
  unsigned char buffer[bufsize + 1];
  unsigned char this_buffer[bufsize + 1];
  int len;

  memset (buffer, 0, bufsize + 1);
  unsigned needed_len = ROUND_UP (maxsizei, BITS_PER_UNIT) / BITS_PER_UNIT;
  while (!partial_defs.is_empty ())
    {
      pd_data pd = partial_defs.pop ();
      unsigned int amnt;
      if (TREE_CODE (pd.rhs) == CONSTRUCTOR)
	{
	  /* Empty CONSTRUCTOR.  */
	  if (pd.size >= needed_len * BITS_PER_UNIT)
	    len = needed_len;
	  else
	    len = ROUND_UP (pd.size, BITS_PER_UNIT) / BITS_PER_UNIT;
	  memset (this_buffer, 0, len);
	}
      else
	{
	  len = native_encode_expr (pd.rhs, this_buffer, bufsize,
				    MAX (0, -pd.offset) / BITS_PER_UNIT);
	  if (len <= 0
	      || len < (ROUND_UP (pd.size, BITS_PER_UNIT) / BITS_PER_UNIT
			- MAX (0, -pd.offset) / BITS_PER_UNIT))
	    {
	      if (dump_file && (dump_flags & TDF_DETAILS))
		fprintf (dump_file, "Failed to encode %u "
			 "partial definitions\n", ndefs);
	      return (void *)-1;
	    }
	}

      unsigned char *p = buffer;
      HOST_WIDE_INT size = pd.size;
      if (pd.offset < 0)
	size -= ROUND_DOWN (-pd.offset, BITS_PER_UNIT);
      this_buffer[len] = 0;
      if (BYTES_BIG_ENDIAN)
	{
	  /* LSB of this_buffer[len - 1] byte should be at
	     pd.offset + pd.size - 1 bits in buffer.  */
	  amnt = ((unsigned HOST_WIDE_INT) pd.offset
		  + pd.size) % BITS_PER_UNIT;
	  if (amnt)
	    shift_bytes_in_array_right (this_buffer, len + 1, amnt);
	  unsigned char *q = this_buffer;
	  unsigned int off = 0;
	  if (pd.offset >= 0)
	    {
	      unsigned int msk;
	      off = pd.offset / BITS_PER_UNIT;
	      gcc_assert (off < needed_len);
	      p = buffer + off;
	      if (size <= amnt)
		{
		  msk = ((1 << size) - 1) << (BITS_PER_UNIT - amnt);
		  *p = (*p & ~msk) | (this_buffer[len] & msk);
		  size = 0;
		}
	      else
		{
		  if (TREE_CODE (pd.rhs) != CONSTRUCTOR)
		    q = (this_buffer + len
			 - (ROUND_UP (size - amnt, BITS_PER_UNIT)
			    / BITS_PER_UNIT));
		  if (pd.offset % BITS_PER_UNIT)
		    {
		      msk = -1U << (BITS_PER_UNIT
				    - (pd.offset % BITS_PER_UNIT));
		      *p = (*p & msk) | (*q & ~msk);
		      p++;
		      q++;
		      off++;
		      size -= BITS_PER_UNIT - (pd.offset % BITS_PER_UNIT);
		      gcc_assert (size >= 0);
		    }
		}
	    }
	  else if (TREE_CODE (pd.rhs) != CONSTRUCTOR)
	    {
	      q = (this_buffer + len
		   - (ROUND_UP (size - amnt, BITS_PER_UNIT)
		      / BITS_PER_UNIT));
	      if (pd.offset % BITS_PER_UNIT)
		{
		  q++;
		  size -= BITS_PER_UNIT - ((unsigned HOST_WIDE_INT) pd.offset
					   % BITS_PER_UNIT);
		  gcc_assert (size >= 0);
		}
	    }
	  if ((unsigned HOST_WIDE_INT) size / BITS_PER_UNIT + off
	      > needed_len)
	    size = (needed_len - off) * BITS_PER_UNIT;
	  memcpy (p, q, size / BITS_PER_UNIT);
	  if (size % BITS_PER_UNIT)
	    {
	      unsigned int msk
		= -1U << (BITS_PER_UNIT - (size % BITS_PER_UNIT));
	      p += size / BITS_PER_UNIT;
	      q += size / BITS_PER_UNIT;
	      *p = (*q & msk) | (*p & ~msk);
	    }
	}
      else
	{
	  if (pd.offset >= 0)
	    {
	      /* LSB of this_buffer[0] byte should be at pd.offset bits
		 in buffer.  */
	      unsigned int msk;
	      size = MIN (size, (HOST_WIDE_INT) needed_len * BITS_PER_UNIT);
	      amnt = pd.offset % BITS_PER_UNIT;
	      if (amnt)
		shift_bytes_in_array_left (this_buffer, len + 1, amnt);
	      unsigned int off = pd.offset / BITS_PER_UNIT;
	      gcc_assert (off < needed_len);
	      size = MIN (size,
			  (HOST_WIDE_INT) (needed_len - off) * BITS_PER_UNIT);
	      p = buffer + off;
	      if (amnt + size < BITS_PER_UNIT)
		{
		  /* Low amnt bits come from *p, then size bits
		     from this_buffer[0] and the remaining again from
		     *p.  */
		  msk = ((1 << size) - 1) << amnt;
		  *p = (*p & ~msk) | (this_buffer[0] & msk);
		  size = 0;
		}
	      else if (amnt)
		{
		  msk = -1U << amnt;
		  *p = (*p & ~msk) | (this_buffer[0] & msk);
		  p++;
		  size -= (BITS_PER_UNIT - amnt);
		}
	    }
	  else
	    {
	      amnt = (unsigned HOST_WIDE_INT) pd.offset % BITS_PER_UNIT;
	      if (amnt)
		size -= BITS_PER_UNIT - amnt;
	      size = MIN (size, (HOST_WIDE_INT) needed_len * BITS_PER_UNIT);
	      if (amnt)
		shift_bytes_in_array_left (this_buffer, len + 1, amnt);
	    }
	  memcpy (p, this_buffer + (amnt != 0), size / BITS_PER_UNIT);
	  p += size / BITS_PER_UNIT;
	  if (size % BITS_PER_UNIT)
	    {
	      unsigned int msk = -1U << (size % BITS_PER_UNIT);
	      *p = (this_buffer[(amnt != 0) + size / BITS_PER_UNIT]
		    & ~msk) | (*p & msk);
	    }
	}
    }

  tree type = vr->type;
  /* Make sure to interpret in a type that has a range covering the whole
     access size.  */
  if (INTEGRAL_TYPE_P (vr->type) && maxsizei != TYPE_PRECISION (vr->type))
    type = build_nonstandard_integer_type (maxsizei, TYPE_UNSIGNED (type));
  tree val;
  if (BYTES_BIG_ENDIAN)
    {
      unsigned sz = needed_len;
      if (maxsizei % BITS_PER_UNIT)
	shift_bytes_in_array_right (buffer, needed_len,
				    BITS_PER_UNIT
				    - (maxsizei % BITS_PER_UNIT));
      if (INTEGRAL_TYPE_P (type))
	sz = GET_MODE_SIZE (SCALAR_INT_TYPE_MODE (type));
      if (sz > needed_len)
	{
	  memcpy (this_buffer + (sz - needed_len), buffer, needed_len);
	  val = native_interpret_expr (type, this_buffer, sz);
	}
      else
	val = native_interpret_expr (type, buffer, needed_len);
    }
  else
    val = native_interpret_expr (type, buffer, bufsize);
  /* If we chop off bits because the types precision doesn't match the memory
     access size this is ok when optimizing reads but not when called from
     the DSE code during elimination.  */
  if (val && type != vr->type)
    {
      if (! int_fits_type_p (val, vr->type))
	val = NULL_TREE;
      else
	val = fold_convert (vr->type, val);
    }

  if (val)
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file,
		 "Successfully combined %u partial definitions\n", ndefs);
      /* We are using the alias-set of the first store we encounter which
	 should be appropriate here.  */
      return finish (first_set, first_base_set, val);
    }
  else
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file,
		 "Failed to interpret %u encoded partial definitions\n", ndefs);
      return (void *)-1;
    }
}

/* Callback for walk_non_aliased_vuses.  Adjusts the vn_reference_t VR_
   with the current VUSE and performs the expression lookup.  */

static void *
vn_reference_lookup_2 (ao_ref *op ATTRIBUTE_UNUSED, tree vuse, void *data_)
{
  vn_walk_cb_data *data = (vn_walk_cb_data *)data_;
  vn_reference_t vr = data->vr;
  vn_reference_s **slot;
  hashval_t hash;

  /* If we have partial definitions recorded we have to go through
     vn_reference_lookup_3.  */
  if (!data->partial_defs.is_empty ())
    return NULL;

  if (data->last_vuse_ptr)
    {
      *data->last_vuse_ptr = vuse;
      data->last_vuse = vuse;
    }

  /* Fixup vuse and hash.  */
  if (vr->vuse)
    vr->hashcode = vr->hashcode - SSA_NAME_VERSION (vr->vuse);
  vr->vuse = vuse_ssa_val (vuse);
  if (vr->vuse)
    vr->hashcode = vr->hashcode + SSA_NAME_VERSION (vr->vuse);

  hash = vr->hashcode;
  slot = valid_info->references->find_slot_with_hash (vr, hash, NO_INSERT);
  if (slot)
    {
      if ((*slot)->result && data->saved_operands.exists ())
	return data->finish (vr->set, vr->base_set, (*slot)->result);
      return *slot;
    }

  return NULL;
}

/* Lookup an existing or insert a new vn_reference entry into the
   value table for the VUSE, SET, TYPE, OPERANDS reference which
   has the value VALUE which is either a constant or an SSA name.  */

static vn_reference_t
vn_reference_lookup_or_insert_for_pieces (tree vuse,
					  alias_set_type set,
					  alias_set_type base_set,
					  tree type,
					  vec<vn_reference_op_s,
					        va_heap> operands,
					  tree value)
{
  vn_reference_s vr1;
  vn_reference_t result;
  unsigned value_id;
  vr1.vuse = vuse ? SSA_VAL (vuse) : NULL_TREE;
  vr1.operands = operands;
  vr1.type = type;
  vr1.set = set;
  vr1.base_set = base_set;
  vr1.hashcode = vn_reference_compute_hash (&vr1);
  if (vn_reference_lookup_1 (&vr1, &result))
    return result;
  if (TREE_CODE (value) == SSA_NAME)
    value_id = VN_INFO (value)->value_id;
  else
    value_id = get_or_alloc_constant_value_id (value);
  return vn_reference_insert_pieces (vuse, set, base_set, type,
				     operands.copy (), value, value_id);
}

/* Return a value-number for RCODE OPS... either by looking up an existing
   value-number for the possibly simplified result or by inserting the
   operation if INSERT is true.  If SIMPLIFY is false, return a value
   number for the unsimplified expression.  */

static tree
vn_nary_build_or_lookup_1 (gimple_match_op *res_op, bool insert,
			   bool simplify)
{
  tree result = NULL_TREE;
  /* We will be creating a value number for
       RCODE (OPS...).
     So first simplify and lookup this expression to see if it
     is already available.  */
  /* For simplification valueize.  */
  unsigned i = 0;
  if (simplify)
    for (i = 0; i < res_op->num_ops; ++i)
      if (TREE_CODE (res_op->ops[i]) == SSA_NAME)
	{
	  tree tem = vn_valueize (res_op->ops[i]);
	  if (!tem)
	    break;
	  res_op->ops[i] = tem;
	}
  /* If valueization of an operand fails (it is not available), skip
     simplification.  */
  bool res = false;
  if (i == res_op->num_ops)
    {
      mprts_hook = vn_lookup_simplify_result;
      res = res_op->resimplify (NULL, vn_valueize);
      mprts_hook = NULL;
    }
  gimple *new_stmt = NULL;
  if (res
      && gimple_simplified_result_is_gimple_val (res_op))
    {
      /* The expression is already available.  */
      result = res_op->ops[0];
      /* Valueize it, simplification returns sth in AVAIL only.  */
      if (TREE_CODE (result) == SSA_NAME)
	result = SSA_VAL (result);
    }
  else
    {
      tree val = vn_lookup_simplify_result (res_op);
      if (!val && insert)
	{
	  gimple_seq stmts = NULL;
	  result = maybe_push_res_to_seq (res_op, &stmts);
	  if (result)
	    {
	      gcc_assert (gimple_seq_singleton_p (stmts));
	      new_stmt = gimple_seq_first_stmt (stmts);
	    }
	}
      else
	/* The expression is already available.  */
	result = val;
    }
  if (new_stmt)
    {
      /* The expression is not yet available, value-number lhs to
	 the new SSA_NAME we created.  */
      /* Initialize value-number information properly.  */
      vn_ssa_aux_t result_info = VN_INFO (result);
      result_info->valnum = result;
      result_info->value_id = get_next_value_id ();
      result_info->visited = 1;
      gimple_seq_add_stmt_without_update (&VN_INFO (result)->expr,
					  new_stmt);
      result_info->needs_insertion = true;
      /* ???  PRE phi-translation inserts NARYs without corresponding
         SSA name result.  Re-use those but set their result according
	 to the stmt we just built.  */
      vn_nary_op_t nary = NULL;
      vn_nary_op_lookup_stmt (new_stmt, &nary);
      if (nary)
	{
	  gcc_assert (! nary->predicated_values && nary->u.result == NULL_TREE);
	  nary->u.result = gimple_assign_lhs (new_stmt);
	}
      /* As all "inserted" statements are singleton SCCs, insert
	 to the valid table.  This is strictly needed to
	 avoid re-generating new value SSA_NAMEs for the same
	 expression during SCC iteration over and over (the
	 optimistic table gets cleared after each iteration).
	 We do not need to insert into the optimistic table, as
	 lookups there will fall back to the valid table.  */
      else
	{
	  unsigned int length = vn_nary_length_from_stmt (new_stmt);
	  vn_nary_op_t vno1
	    = alloc_vn_nary_op_noinit (length, &vn_tables_insert_obstack);
	  vno1->value_id = result_info->value_id;
	  vno1->length = length;
	  vno1->predicated_values = 0;
	  vno1->u.result = result;
	  init_vn_nary_op_from_stmt (vno1, as_a <gassign *> (new_stmt));
	  vn_nary_op_insert_into (vno1, valid_info->nary, true);
	  /* Also do not link it into the undo chain.  */
	  last_inserted_nary = vno1->next;
	  vno1->next = (vn_nary_op_t)(void *)-1;
	}
      if (dump_file && (dump_flags & TDF_DETAILS))
	{
	  fprintf (dump_file, "Inserting name ");
	  print_generic_expr (dump_file, result);
	  fprintf (dump_file, " for expression ");
	  print_gimple_expr (dump_file, new_stmt, 0, TDF_SLIM);
	  fprintf (dump_file, "\n");
	}
    }
  return result;
}

/* Return a value-number for RCODE OPS... either by looking up an existing
   value-number for the simplified result or by inserting the operation.  */

static tree
vn_nary_build_or_lookup (gimple_match_op *res_op)
{
  return vn_nary_build_or_lookup_1 (res_op, true, true);
}

/* Try to simplify the expression RCODE OPS... of type TYPE and return
   its value if present.  */

tree
vn_nary_simplify (vn_nary_op_t nary)
{
  if (nary->length > gimple_match_op::MAX_NUM_OPS)
    return NULL_TREE;
  gimple_match_op op (gimple_match_cond::UNCOND, nary->opcode,
		      nary->type, nary->length);
  memcpy (op.ops, nary->op, sizeof (tree) * nary->length);
  return vn_nary_build_or_lookup_1 (&op, false, true);
}

/* Elimination engine.  */

class eliminate_dom_walker : public dom_walker
{
public:
  eliminate_dom_walker (cdi_direction, bitmap);
  ~eliminate_dom_walker ();

  virtual edge before_dom_children (basic_block);
  virtual void after_dom_children (basic_block);

  virtual tree eliminate_avail (basic_block, tree op);
  virtual void eliminate_push_avail (basic_block, tree op);
  tree eliminate_insert (basic_block, gimple_stmt_iterator *gsi, tree val);

  void eliminate_stmt (basic_block, gimple_stmt_iterator *);

  unsigned eliminate_cleanup (bool region_p = false);

  bool do_pre;
  unsigned int el_todo;
  unsigned int eliminations;
  unsigned int insertions;

  /* SSA names that had their defs inserted by PRE if do_pre.  */
  bitmap inserted_exprs;

  /* Blocks with statements that have had their EH properties changed.  */
  bitmap need_eh_cleanup;

  /* Blocks with statements that have had their AB properties changed.  */
  bitmap need_ab_cleanup;

  /* Local state for the eliminate domwalk.  */
  auto_vec<gimple *> to_remove;
  auto_vec<gimple *> to_fixup;
  auto_vec<tree> avail;
  auto_vec<tree> avail_stack;
};

/* Adaptor to the elimination engine using RPO availability.  */

class rpo_elim : public eliminate_dom_walker
{
public:
  rpo_elim(basic_block entry_)
    : eliminate_dom_walker (CDI_DOMINATORS, NULL), entry (entry_),
      m_avail_freelist (NULL) {}

  virtual tree eliminate_avail (basic_block, tree op);

  virtual void eliminate_push_avail (basic_block, tree);

  basic_block entry;
  /* Freelist of avail entries which are allocated from the vn_ssa_aux
     obstack.  */
  vn_avail *m_avail_freelist;
};

/* Global RPO state for access from hooks.  */
static eliminate_dom_walker *rpo_avail;
basic_block vn_context_bb;

/* Return true if BASE1 and BASE2 can be adjusted so they have the
   same address and adjust *OFFSET1 and *OFFSET2 accordingly.
   Otherwise return false.  */

static bool
adjust_offsets_for_equal_base_address (tree base1, poly_int64 *offset1,
				       tree base2, poly_int64 *offset2)
{
  poly_int64 soff;
  if (TREE_CODE (base1) == MEM_REF
      && TREE_CODE (base2) == MEM_REF)
    {
      if (mem_ref_offset (base1).to_shwi (&soff))
	{
	  base1 = TREE_OPERAND (base1, 0);
	  *offset1 += soff * BITS_PER_UNIT;
	}
      if (mem_ref_offset (base2).to_shwi (&soff))
	{
	  base2 = TREE_OPERAND (base2, 0);
	  *offset2 += soff * BITS_PER_UNIT;
	}
      return operand_equal_p (base1, base2, 0);
    }
  return operand_equal_p (base1, base2, OEP_ADDRESS_OF);
}

/* Callback for walk_non_aliased_vuses.  Tries to perform a lookup
   from the statement defining VUSE and if not successful tries to
   translate *REFP and VR_ through an aggregate copy at the definition
   of VUSE.  If *DISAMBIGUATE_ONLY is true then do not perform translation
   of *REF and *VR.  If only disambiguation was performed then
   *DISAMBIGUATE_ONLY is set to true.  */

static void *
vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
		       translate_flags *disambiguate_only)
{
  vn_walk_cb_data *data = (vn_walk_cb_data *)data_;
  vn_reference_t vr = data->vr;
  gimple *def_stmt = SSA_NAME_DEF_STMT (vuse);
  tree base = ao_ref_base (ref);
  HOST_WIDE_INT offseti = 0, maxsizei, sizei = 0;
  static vec<vn_reference_op_s> lhs_ops;
  ao_ref lhs_ref;
  bool lhs_ref_ok = false;
  poly_int64 copy_size;

  /* First try to disambiguate after value-replacing in the definitions LHS.  */
  if (is_gimple_assign (def_stmt))
    {
      tree lhs = gimple_assign_lhs (def_stmt);
      bool valueized_anything = false;
      /* Avoid re-allocation overhead.  */
      lhs_ops.truncate (0);
      basic_block saved_rpo_bb = vn_context_bb;
      vn_context_bb = gimple_bb (def_stmt);
      if (*disambiguate_only <= TR_VALUEIZE_AND_DISAMBIGUATE)
	{
	  copy_reference_ops_from_ref (lhs, &lhs_ops);
	  valueize_refs_1 (&lhs_ops, &valueized_anything, true);
	}
      vn_context_bb = saved_rpo_bb;
      ao_ref_init (&lhs_ref, lhs);
      lhs_ref_ok = true;
      if (valueized_anything
	  && ao_ref_init_from_vn_reference
	       (&lhs_ref, ao_ref_alias_set (&lhs_ref),
		ao_ref_base_alias_set (&lhs_ref), TREE_TYPE (lhs), lhs_ops)
	  && !refs_may_alias_p_1 (ref, &lhs_ref, data->tbaa_p))
	{
	  *disambiguate_only = TR_VALUEIZE_AND_DISAMBIGUATE;
	  return NULL;
	}

      /* Besides valueizing the LHS we can also use access-path based
         disambiguation on the original non-valueized ref.  */
      if (!ref->ref
	  && lhs_ref_ok
	  && data->orig_ref.ref)
	{
	  /* We want to use the non-valueized LHS for this, but avoid redundant
	     work.  */
	  ao_ref *lref = &lhs_ref;
	  ao_ref lref_alt;
	  if (valueized_anything)
	    {
	      ao_ref_init (&lref_alt, lhs);
	      lref = &lref_alt;
	    }
	  if (!refs_may_alias_p_1 (&data->orig_ref, lref, data->tbaa_p))
	    {
	      *disambiguate_only = (valueized_anything
				    ? TR_VALUEIZE_AND_DISAMBIGUATE
				    : TR_DISAMBIGUATE);
	      return NULL;
	    }
	}

      /* If we reach a clobbering statement try to skip it and see if
         we find a VN result with exactly the same value as the
	 possible clobber.  In this case we can ignore the clobber
	 and return the found value.  */
      if (is_gimple_reg_type (TREE_TYPE (lhs))
	  && types_compatible_p (TREE_TYPE (lhs), vr->type)
	  && (ref->ref || data->orig_ref.ref))
	{
	  tree *saved_last_vuse_ptr = data->last_vuse_ptr;
	  /* Do not update last_vuse_ptr in vn_reference_lookup_2.  */
	  data->last_vuse_ptr = NULL;
	  tree saved_vuse = vr->vuse;
	  hashval_t saved_hashcode = vr->hashcode;
	  void *res = vn_reference_lookup_2 (ref, gimple_vuse (def_stmt), data);
	  /* Need to restore vr->vuse and vr->hashcode.  */
	  vr->vuse = saved_vuse;
	  vr->hashcode = saved_hashcode;
	  data->last_vuse_ptr = saved_last_vuse_ptr;
	  if (res && res != (void *)-1)
	    {
	      vn_reference_t vnresult = (vn_reference_t) res;
	      tree rhs = gimple_assign_rhs1 (def_stmt);
	      if (TREE_CODE (rhs) == SSA_NAME)
		rhs = SSA_VAL (rhs);
	      if (vnresult->result
		  && operand_equal_p (vnresult->result, rhs, 0)
		  /* We have to honor our promise about union type punning
		     and also support arbitrary overlaps with
		     -fno-strict-aliasing.  So simply resort to alignment to
		     rule out overlaps.  Do this check last because it is
		     quite expensive compared to the hash-lookup above.  */
		  && multiple_p (get_object_alignment
				   (ref->ref ? ref->ref : data->orig_ref.ref),
				 ref->size)
		  && multiple_p (get_object_alignment (lhs), ref->size))
		return res;
	    }
	}
    }
  else if (*disambiguate_only <= TR_VALUEIZE_AND_DISAMBIGUATE
	   && gimple_call_builtin_p (def_stmt, BUILT_IN_NORMAL)
	   && gimple_call_num_args (def_stmt) <= 4)
    {
      /* For builtin calls valueize its arguments and call the
         alias oracle again.  Valueization may improve points-to
	 info of pointers and constify size and position arguments.
	 Originally this was motivated by PR61034 which has
	 conditional calls to free falsely clobbering ref because
	 of imprecise points-to info of the argument.  */
      tree oldargs[4];
      bool valueized_anything = false;
      for (unsigned i = 0; i < gimple_call_num_args (def_stmt); ++i)
	{
	  oldargs[i] = gimple_call_arg (def_stmt, i);
	  tree val = vn_valueize (oldargs[i]);
	  if (val != oldargs[i])
	    {
	      gimple_call_set_arg (def_stmt, i, val);
	      valueized_anything = true;
	    }
	}
      if (valueized_anything)
	{
	  bool res = call_may_clobber_ref_p_1 (as_a <gcall *> (def_stmt),
					       ref, data->tbaa_p);
	  for (unsigned i = 0; i < gimple_call_num_args (def_stmt); ++i)
	    gimple_call_set_arg (def_stmt, i, oldargs[i]);
	  if (!res)
	    {
	      *disambiguate_only = TR_VALUEIZE_AND_DISAMBIGUATE;
	      return NULL;
	    }
	}
    }

  if (*disambiguate_only > TR_TRANSLATE)
    return (void *)-1;

  /* If we cannot constrain the size of the reference we cannot
     test if anything kills it.  */
  if (!ref->max_size_known_p ())
    return (void *)-1;

  poly_int64 offset = ref->offset;
  poly_int64 maxsize = ref->max_size;

  /* def_stmt may-defs *ref.  See if we can derive a value for *ref
     from that definition.
     1) Memset.  */
  if (is_gimple_reg_type (vr->type)
      && (gimple_call_builtin_p (def_stmt, BUILT_IN_MEMSET)
	  || gimple_call_builtin_p (def_stmt, BUILT_IN_MEMSET_CHK))
      && (integer_zerop (gimple_call_arg (def_stmt, 1))
	  || ((TREE_CODE (gimple_call_arg (def_stmt, 1)) == INTEGER_CST
	       || (INTEGRAL_TYPE_P (vr->type) && known_eq (ref->size, 8)))
	      && CHAR_BIT == 8
	      && BITS_PER_UNIT == 8
	      && BYTES_BIG_ENDIAN == WORDS_BIG_ENDIAN
	      && offset.is_constant (&offseti)
	      && ref->size.is_constant (&sizei)
	      && (offseti % BITS_PER_UNIT == 0
		  || TREE_CODE (gimple_call_arg (def_stmt, 1)) == INTEGER_CST)))
      && (poly_int_tree_p (gimple_call_arg (def_stmt, 2))
	  || (TREE_CODE (gimple_call_arg (def_stmt, 2)) == SSA_NAME
	      && poly_int_tree_p (SSA_VAL (gimple_call_arg (def_stmt, 2)))))
      && (TREE_CODE (gimple_call_arg (def_stmt, 0)) == ADDR_EXPR
	  || TREE_CODE (gimple_call_arg (def_stmt, 0)) == SSA_NAME))
    {
      tree base2;
      poly_int64 offset2, size2, maxsize2;
      bool reverse;
      tree ref2 = gimple_call_arg (def_stmt, 0);
      if (TREE_CODE (ref2) == SSA_NAME)
	{
	  ref2 = SSA_VAL (ref2);
	  if (TREE_CODE (ref2) == SSA_NAME
	      && (TREE_CODE (base) != MEM_REF
		  || TREE_OPERAND (base, 0) != ref2))
	    {
	      gimple *def_stmt = SSA_NAME_DEF_STMT (ref2);
	      if (gimple_assign_single_p (def_stmt)
		  && gimple_assign_rhs_code (def_stmt) == ADDR_EXPR)
		ref2 = gimple_assign_rhs1 (def_stmt);
	    }
	}
      if (TREE_CODE (ref2) == ADDR_EXPR)
	{
	  ref2 = TREE_OPERAND (ref2, 0);
	  base2 = get_ref_base_and_extent (ref2, &offset2, &size2, &maxsize2,
					   &reverse);
	  if (!known_size_p (maxsize2)
	      || !known_eq (maxsize2, size2)
	      || !operand_equal_p (base, base2, OEP_ADDRESS_OF))
	    return (void *)-1;
	}
      else if (TREE_CODE (ref2) == SSA_NAME)
	{
	  poly_int64 soff;
	  if (TREE_CODE (base) != MEM_REF
	      || !(mem_ref_offset (base)
		   << LOG2_BITS_PER_UNIT).to_shwi (&soff))
	    return (void *)-1;
	  offset += soff;
	  offset2 = 0;
	  if (TREE_OPERAND (base, 0) != ref2)
	    {
	      gimple *def = SSA_NAME_DEF_STMT (ref2);
	      if (is_gimple_assign (def)
		  && gimple_assign_rhs_code (def) == POINTER_PLUS_EXPR
		  && gimple_assign_rhs1 (def) == TREE_OPERAND (base, 0)
		  && poly_int_tree_p (gimple_assign_rhs2 (def)))
		{
		  tree rhs2 = gimple_assign_rhs2 (def);
		  if (!(poly_offset_int::from (wi::to_poly_wide (rhs2),
					       SIGNED)
			<< LOG2_BITS_PER_UNIT).to_shwi (&offset2))
		    return (void *)-1;
		  ref2 = gimple_assign_rhs1 (def);
		  if (TREE_CODE (ref2) == SSA_NAME)
		    ref2 = SSA_VAL (ref2);
		}
	      else
		return (void *)-1;
	    }
	}
      else
	return (void *)-1;
      tree len = gimple_call_arg (def_stmt, 2);
      HOST_WIDE_INT leni, offset2i;
      if (TREE_CODE (len) == SSA_NAME)
	len = SSA_VAL (len);
      /* Sometimes the above trickery is smarter than alias analysis.  Take
         advantage of that.  */
      if (!ranges_maybe_overlap_p (offset, maxsize, offset2,
				   (wi::to_poly_offset (len)
				    << LOG2_BITS_PER_UNIT)))
	return NULL;
      if (data->partial_defs.is_empty ()
	  && known_subrange_p (offset, maxsize, offset2,
			       wi::to_poly_offset (len) << LOG2_BITS_PER_UNIT))
	{
	  tree val;
	  if (integer_zerop (gimple_call_arg (def_stmt, 1)))
	    val = build_zero_cst (vr->type);
	  else if (INTEGRAL_TYPE_P (vr->type)
		   && known_eq (ref->size, 8)
		   && offseti % BITS_PER_UNIT == 0)
	    {
	      gimple_match_op res_op (gimple_match_cond::UNCOND, NOP_EXPR,
				      vr->type, gimple_call_arg (def_stmt, 1));
	      val = vn_nary_build_or_lookup (&res_op);
	      if (!val
		  || (TREE_CODE (val) == SSA_NAME
		      && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (val)))
		return (void *)-1;
	    }
	  else
	    {
	      unsigned buflen = TREE_INT_CST_LOW (TYPE_SIZE_UNIT (vr->type)) + 1;
	      if (INTEGRAL_TYPE_P (vr->type))
		buflen = GET_MODE_SIZE (SCALAR_INT_TYPE_MODE (vr->type)) + 1;
	      unsigned char *buf = XALLOCAVEC (unsigned char, buflen);
	      memset (buf, TREE_INT_CST_LOW (gimple_call_arg (def_stmt, 1)),
		      buflen);
	      if (BYTES_BIG_ENDIAN)
		{
		  unsigned int amnt
		    = (((unsigned HOST_WIDE_INT) offseti + sizei)
		       % BITS_PER_UNIT);
		  if (amnt)
		    {
		      shift_bytes_in_array_right (buf, buflen,
						  BITS_PER_UNIT - amnt);
		      buf++;
		      buflen--;
		    }
		}
	      else if (offseti % BITS_PER_UNIT != 0)
		{
		  unsigned int amnt
		    = BITS_PER_UNIT - ((unsigned HOST_WIDE_INT) offseti
				       % BITS_PER_UNIT);
		  shift_bytes_in_array_left (buf, buflen, amnt);
		  buf++;
		  buflen--;
		}
	      val = native_interpret_expr (vr->type, buf, buflen);
	      if (!val)
		return (void *)-1;
	    }
	  return data->finish (0, 0, val);
	}
      /* For now handle clearing memory with partial defs.  */
      else if (known_eq (ref->size, maxsize)
	       && integer_zerop (gimple_call_arg (def_stmt, 1))
	       && tree_fits_poly_int64_p (len)
	       && tree_to_poly_int64 (len).is_constant (&leni)
	       && leni <= INTTYPE_MAXIMUM (HOST_WIDE_INT) / BITS_PER_UNIT
	       && offset.is_constant (&offseti)
	       && offset2.is_constant (&offset2i)
	       && maxsize.is_constant (&maxsizei)
	       && ranges_known_overlap_p (offseti, maxsizei, offset2i,
					  leni << LOG2_BITS_PER_UNIT))
	{
	  pd_data pd;
	  pd.rhs = build_constructor (NULL_TREE, NULL);
	  pd.offset = offset2i;
	  pd.size = leni << LOG2_BITS_PER_UNIT;
	  return data->push_partial_def (pd, 0, 0, offseti, maxsizei);
	}
    }

  /* 2) Assignment from an empty CONSTRUCTOR.  */
  else if (is_gimple_reg_type (vr->type)
	   && gimple_assign_single_p (def_stmt)
	   && gimple_assign_rhs_code (def_stmt) == CONSTRUCTOR
	   && CONSTRUCTOR_NELTS (gimple_assign_rhs1 (def_stmt)) == 0)
    {
      tree base2;
      poly_int64 offset2, size2, maxsize2;
      HOST_WIDE_INT offset2i, size2i;
      gcc_assert (lhs_ref_ok);
      base2 = ao_ref_base (&lhs_ref);
      offset2 = lhs_ref.offset;
      size2 = lhs_ref.size;
      maxsize2 = lhs_ref.max_size;
      if (known_size_p (maxsize2)
	  && known_eq (maxsize2, size2)
	  && adjust_offsets_for_equal_base_address (base, &offset,
						    base2, &offset2))
	{
	  if (data->partial_defs.is_empty ()
	      && known_subrange_p (offset, maxsize, offset2, size2))
	    {
	      /* While technically undefined behavior do not optimize
	         a full read from a clobber.  */
	      if (gimple_clobber_p (def_stmt))
		return (void *)-1;
	      tree val = build_zero_cst (vr->type);
	      return data->finish (ao_ref_alias_set (&lhs_ref),
				   ao_ref_base_alias_set (&lhs_ref), val);
	    }
	  else if (known_eq (ref->size, maxsize)
		   && maxsize.is_constant (&maxsizei)
		   && offset.is_constant (&offseti)
		   && offset2.is_constant (&offset2i)
		   && size2.is_constant (&size2i)
		   && ranges_known_overlap_p (offseti, maxsizei,
					      offset2i, size2i))
	    {
	      /* Let clobbers be consumed by the partial-def tracker
	         which can choose to ignore them if they are shadowed
		 by a later def.  */
	      pd_data pd;
	      pd.rhs = gimple_assign_rhs1 (def_stmt);
	      pd.offset = offset2i;
	      pd.size = size2i;
	      return data->push_partial_def (pd, ao_ref_alias_set (&lhs_ref),
					     ao_ref_base_alias_set (&lhs_ref),
					     offseti, maxsizei);
	    }
	}
    }

  /* 3) Assignment from a constant.  We can use folds native encode/interpret
     routines to extract the assigned bits.  */
  else if (known_eq (ref->size, maxsize)
	   && is_gimple_reg_type (vr->type)
	   && !reverse_storage_order_for_component_p (vr->operands)
	   && !contains_storage_order_barrier_p (vr->operands)
	   && gimple_assign_single_p (def_stmt)
	   && CHAR_BIT == 8
	   && BITS_PER_UNIT == 8
	   && BYTES_BIG_ENDIAN == WORDS_BIG_ENDIAN
	   /* native_encode and native_decode operate on arrays of bytes
	      and so fundamentally need a compile-time size and offset.  */
	   && maxsize.is_constant (&maxsizei)
	   && offset.is_constant (&offseti)
	   && (is_gimple_min_invariant (gimple_assign_rhs1 (def_stmt))
	       || (TREE_CODE (gimple_assign_rhs1 (def_stmt)) == SSA_NAME
		   && is_gimple_min_invariant (SSA_VAL (gimple_assign_rhs1 (def_stmt))))))
    {
      tree lhs = gimple_assign_lhs (def_stmt);
      tree base2;
      poly_int64 offset2, size2, maxsize2;
      HOST_WIDE_INT offset2i, size2i;
      bool reverse;
      gcc_assert (lhs_ref_ok);
      base2 = ao_ref_base (&lhs_ref);
      offset2 = lhs_ref.offset;
      size2 = lhs_ref.size;
      maxsize2 = lhs_ref.max_size;
      reverse = reverse_storage_order_for_component_p (lhs);
      if (base2
	  && !reverse
	  && !storage_order_barrier_p (lhs)
	  && known_eq (maxsize2, size2)
	  && adjust_offsets_for_equal_base_address (base, &offset,
						    base2, &offset2)
	  && offset.is_constant (&offseti)
	  && offset2.is_constant (&offset2i)
	  && size2.is_constant (&size2i))
	{
	  if (data->partial_defs.is_empty ()
	      && known_subrange_p (offseti, maxsizei, offset2, size2))
	    {
	      /* We support up to 512-bit values (for V8DFmode).  */
	      unsigned char buffer[65];
	      int len;

	      tree rhs = gimple_assign_rhs1 (def_stmt);
	      if (TREE_CODE (rhs) == SSA_NAME)
		rhs = SSA_VAL (rhs);
	      len = native_encode_expr (rhs,
					buffer, sizeof (buffer) - 1,
					(offseti - offset2i) / BITS_PER_UNIT);
	      if (len > 0 && len * BITS_PER_UNIT >= maxsizei)
		{
		  tree type = vr->type;
		  unsigned char *buf = buffer;
		  unsigned int amnt =