gcc/tree-ssa-sccvn.c

/* SCC value numbering for trees
   Copyright (C) 2006-2018 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 "backend.h"
#include "rtl.h"
#include "tree.h"
#include "gimple.h"
#include "alloc-pool.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 "params.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-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.
*/


static tree *last_vuse_ptr;
static vn_lookup_kind vn_walk_kind;
static vn_lookup_kind default_vn_walk_kind;
bitmap const_parms;

/* 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 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 : pointer_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 *);
  static inline void remove (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 vn_phi_eq (vp1, vp2);
}

/* Free a phi operation structure VP.  */

inline void
vn_phi_hasher::remove (vn_phi_s *phi)
{
  phi->phiargs.release ();
}

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));
}

/* 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 : pointer_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 *);
  static inline void remove (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 vn_reference_eq (v, c);
}

inline void
vn_reference_hasher::remove (vn_reference_s *v)
{
  free_reference (v);
}

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


/* The set of hashtables and alloc_pool's for their items.  */

typedef struct vn_tables_s
{
  vn_nary_op_table_type *nary;
  vn_phi_table_type *phis;
  vn_reference_table_type *references;
  struct obstack nary_obstack;
  object_allocator<vn_phi_s> *phis_pool;
  object_allocator<vn_reference_s> *references_pool;
} *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;
static bitmap constant_value_ids;


/* Valid hashtables storing information we have proven to be
   correct.  */

static vn_tables_t valid_info;

/* Optimistic hashtables storing information we are making assumptions about
   during iterations.  */

static vn_tables_t optimistic_info;

/* Pointer to the set of hashtables that is currently being used.
   Should always point to either the optimistic_info, or the
   valid_info.  */

static vn_tables_t current_info;


/* Reverse post order index for each basic block.  */

static int *rpo_numbers;

#define SSA_VAL(x) (VN_INFO ((x))->valnum)

/* 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
    {
      tree tem = SSA_VAL (x);
      /* stmt walking can walk over a backedge and reach code we didn't
	 value-number yet.  */
      if (tem == VN_TOP)
	return x;
      x = tem;
    }
  while (SSA_NAME_IN_FREE_LIST (x));

  return x;
}

/* 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;

/* Next DFS number and the stack for strongly connected component
   detection. */

static unsigned int next_dfs_num;
static vec<tree> sccstack;



/* 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.  */

static vec<vn_ssa_aux_t> vn_ssa_aux_table;
static struct obstack vn_ssa_aux_obstack;

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

bool
has_VN_INFO (tree name)
{
  if (SSA_NAME_VERSION (name) < vn_ssa_aux_table.length ())
    return vn_ssa_aux_table[SSA_NAME_VERSION (name)] != NULL;
  return false;
}

/* Return the value numbering information for a given SSA name.  */

vn_ssa_aux_t
VN_INFO (tree name)
{
  vn_ssa_aux_t res = vn_ssa_aux_table[SSA_NAME_VERSION (name)];
  gcc_checking_assert (res);
  return res;
}

/* Set the value numbering info for a given SSA name to a given
   value.  */

static inline void
VN_INFO_SET (tree name, vn_ssa_aux_t value)
{
  vn_ssa_aux_table[SSA_NAME_VERSION (name)] = value;
}

/* Initialize the value numbering info for a given SSA name.
   This should be called just once for every SSA name.  */

vn_ssa_aux_t
VN_INFO_GET (tree name)
{
  vn_ssa_aux_t newinfo;

  gcc_assert (SSA_NAME_VERSION (name) >= vn_ssa_aux_table.length ()
	      || vn_ssa_aux_table[SSA_NAME_VERSION (name)] == NULL);
  newinfo = XOBNEW (&vn_ssa_aux_obstack, struct vn_ssa_aux);
  memset (newinfo, 0, sizeof (struct vn_ssa_aux));
  if (SSA_NAME_VERSION (name) >= vn_ssa_aux_table.length ())
    vn_ssa_aux_table.safe_grow_cleared (SSA_NAME_VERSION (name) + 1);
  vn_ssa_aux_table[SSA_NAME_VERSION (name)] = newinfo;
  return newinfo;
}


/* 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)
		  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;

  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_value_id ();
  *slot = vcp;
  bitmap_set_bit (constant_value_ids, vcp->value_id);
  return vcp->value_id;
}

/* Return true if V is a value id for a constant.  */

bool
value_id_constant_p (unsigned int v)
{
  return bitmap_bit_p (constant_value_ids, v);
}

/* 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->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 (!expressions_equal_p (TYPE_SIZE (vr1->type), TYPE_SIZE (vr2->type)))
    return false;

  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;
      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;
	  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;
	  if (known_eq (vro2->off, -1))
	    break;
	  off2 += vro2->off;
	}
      if (maybe_ne (off1, off2))
	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)
{
  if (TREE_CODE (ref) == TARGET_MEM_REF)
    {
      vn_reference_op_s temp;

      result->reserve (3);

      memset (&temp, 0, sizeof (temp));
      temp.type = TREE_TYPE (ref);
      temp.opcode = TREE_CODE (ref);
      temp.op0 = TMR_INDEX (ref);
      temp.op1 = TMR_STEP (ref);
      temp.op2 = TMR_OFFSET (ref);
      temp.off = -1;
      temp.clique = MR_DEPENDENCE_CLIQUE (ref);
      temp.base = MR_DEPENDENCE_BASE (ref);
      result->quick_push (temp);

      memset (&temp, 0, sizeof (temp));
      temp.type = NULL_TREE;
      temp.opcode = ERROR_MARK;
      temp.op0 = TMR_INDEX2 (ref);
      temp.off = -1;
      result->quick_push (temp);

      memset (&temp, 0, sizeof (temp));
      temp.type = NULL_TREE;
      temp.opcode = TREE_CODE (TMR_BASE (ref));
      temp.op0 = TMR_BASE (ref);
      temp.off = -1;
      result->quick_push (temp);
      return;
    }

  /* 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 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,
	     a matching type is not necessary and a mismatching type
	     is always a spurious difference.  */
	  temp.type = NULL_TREE;
	  temp.op0 = TREE_OPERAND (ref, 1);
	  temp.op1 = TREE_OPERAND (ref, 2);
	  {
	    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
		       (checking cfun->after_inlining does the
		       trick here).  */
		    if (TREE_CODE (orig) != ADDR_EXPR
			|| maybe_ne (off, 0)
			|| cfun->after_inlining)
		      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);
	      }
	  }
	  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 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, tree type,
			       vec<vn_reference_op_s> ops)
{
  vn_reference_op_t op;
  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;
  alias_set_type base_alias_set = -1;

  /* First get the final access size from just the outermost expression.  */
  op = &ops[0];
  if (op->opcode == COMPONENT_REF)
    size_tree = DECL_SIZE (op->op0);
  else if (op->opcode == BIT_FIELD_REF)
    size_tree = op->op0;
  else
    {
      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);

  /* 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)))
	    {
	      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:
	  base_alias_set = get_deref_alias_set (op->op0);
	  *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_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 (TREE_TYPE (op->op0)));
	      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;
  if (base_alias_set != -1)
    ref->base_alias_set = base_alias_set;
  else
    ref->base_alias_set = get_alias_set (base);
  /* 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_return_type (call);
  temp.opcode = CALL_EXPR;
  temp.op0 = gimple_call_fn (call);
  temp.op1 = gimple_call_chain (call);
  if (stmt_could_throw_p (call) && (lr = lookup_stmt_eh_lp (call)) > 0)
    temp.op2 = size_int (lr);
  temp.off = -1;
  if (gimple_call_with_bounds_p (call))
    temp.with_bounds = 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 (TREE_OPERAND (op->op0, 0),
					     &addr_offset);
  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)
{
  unsigned int i = *i_p;
  vn_reference_op_t 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 false;

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

  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 (TREE_OPERAND (addr, 0),
						 &addr_offset);
      /* 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 false;

      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)
	  || TREE_CODE (ptroff) != INTEGER_CST)
	return false;

      off += wi::to_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;
  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);

  /* And recurse.  */
  if (TREE_CODE (op->op0) == SSA_NAME)
    vn_reference_maybe_forwprop_address (ops, i_p);
  else if (TREE_CODE (op->op0) == ADDR_EXPR)
    vn_reference_fold_indirect (ops, i_p);
  return true;
}

/* 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
      && TREE_CODE (op->op0) == ADDR_EXPR
      && TREE_CODE (TREE_OPERAND (op->op0, 0)) == FUNCTION_DECL
      && DECL_BUILT_IN (TREE_OPERAND (op->op0, 0))
      && 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)
	{
	  tree folded = build_call_expr (TREE_OPERAND (op->op0, 0),
					 arg1 ? 2 : 1,
					 arg0->op0,
					 arg1 ? arg1->op0 : NULL);
	  if (folded
	      && TREE_CODE (folded) == NOP_EXPR)
	    folded = TREE_OPERAND (folded, 0);
	  if (folded
	      && is_gimple_min_invariant (folded))
	    return folded;
	}
    }

  /* Simplify reads from constants or constant initializers.  */
  else if (BITS_PER_UNIT == 8
	   && is_gimple_reg_type (ref->type)
	   && (!INTEGRAL_TYPE_P (ref->type)
	       || TYPE_PRECISION (ref->type) % BITS_PER_UNIT == 0))
    {
      poly_int64 off = 0;
      HOST_WIDE_INT size;
      if (INTEGRAL_TYPE_P (ref->type))
	size = TYPE_PRECISION (ref->type);
      else
	size = tree_to_shwi (TYPE_SIZE (ref->type));
      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;
}

/* 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 vec<vn_reference_op_s> 
valueize_refs_1 (vec<vn_reference_op_s> orig, bool *valueized_anything)
{
  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 = 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 = 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 = 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);
	}
    }

  return orig;
}

static vec<vn_reference_op_s> 
valueize_refs (vec<vn_reference_op_s> orig)
{
  bool tem;
  return 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);
  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);
  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 = current_info->references->find_slot_with_hash (vr, hash, NO_INSERT);
  if (!slot && current_info == optimistic_info)
    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;
}

/* 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,
		       unsigned int cnt, void *vr_)
{
  vn_reference_t vr = (vn_reference_t)vr_;
  vn_reference_s **slot;
  hashval_t hash;

  /* This bounds the stmt walks we perform on reference lookups
     to O(1) instead of O(N) where N is the number of dominating
     stores.  */
  if (cnt > (unsigned) PARAM_VALUE (PARAM_SCCVN_MAX_ALIAS_QUERIES_PER_ACCESS))
    return (void *)-1;

  if (last_vuse_ptr)
    *last_vuse_ptr = 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 = current_info->references->find_slot_with_hash (vr, hash, NO_INSERT);
  if (!slot && current_info == optimistic_info)
    slot = valid_info->references->find_slot_with_hash (vr, hash, NO_INSERT);
  if (slot)
    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,
					  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.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, type,
				     operands.copy (), value, value_id);
}

static vn_nary_op_t vn_nary_op_insert_stmt (gimple *stmt, tree result);
static unsigned mprts_hook_cnt;

/* Hook for maybe_push_res_to_seq, lookup the expression in the VN tables.  */

static tree
vn_lookup_simplify_result (code_helper rcode, tree type, tree *ops_)
{
  if (!rcode.is_tree_code ())
    return NULL_TREE;
  tree *ops = ops_;
  unsigned int length = TREE_CODE_LENGTH ((tree_code) rcode);
  if (rcode == CONSTRUCTOR
      /* ???  We're arriving here with SCCVNs view, decomposed CONSTRUCTOR
         and GIMPLEs / match-and-simplifies, CONSTRUCTOR as GENERIC tree.  */
      && TREE_CODE (ops_[0]) == CONSTRUCTOR)
    {
      length = CONSTRUCTOR_NELTS (ops_[0]);
      ops = XALLOCAVEC (tree, length);
      for (unsigned i = 0; i < length; ++i)
	ops[i] = CONSTRUCTOR_ELT (ops_[0], i)->value;
    }
  vn_nary_op_t vnresult = NULL;
  tree res = vn_nary_op_lookup_pieces (length, (tree_code) rcode,
				       type, ops, &vnresult);
  /* We can end up endlessly recursing simplifications if the lookup above
     presents us with a def-use chain that mirrors the original simplification.
     See PR80887 for an example.  Limit successful lookup artificially
     to 10 times if we are called as mprts_hook.  */
  if (res
      && mprts_hook
      && --mprts_hook_cnt == 0)
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, "Resetting mprts_hook after too many "
		 "invocations.\n");
      mprts_hook = NULL;
    }
  return res;
}

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

static tree
vn_nary_build_or_lookup_1 (code_helper rcode, tree type, tree *ops,
			   bool insert)
{
  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.  */
  mprts_hook = vn_lookup_simplify_result;
  mprts_hook_cnt = 9;
  bool res = false;
  switch (TREE_CODE_LENGTH ((tree_code) rcode))
    {
    case 1:
      res = gimple_resimplify1 (NULL, &rcode, type, ops, vn_valueize);
      break;
    case 2:
      res = gimple_resimplify2 (NULL, &rcode, type, ops, vn_valueize);
      break;
    case 3:
      res = gimple_resimplify3 (NULL, &rcode, type, ops, vn_valueize);
      break;
    }
  mprts_hook = NULL;
  gimple *new_stmt = NULL;
  if (res
      && gimple_simplified_result_is_gimple_val (rcode, ops))
    /* The expression is already available.  */
    result = ops[0];
  else
    {
      tree val = vn_lookup_simplify_result (rcode, type, ops);
      if (!val && insert)
	{
	  gimple_seq stmts = NULL;
	  result = maybe_push_res_to_seq (rcode, type, ops, &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_INFO_GET (result)->valnum = result;
      VN_INFO (result)->value_id = get_next_value_id ();
      gimple_seq_add_stmt_without_update (&VN_INFO (result)->expr,
					  new_stmt);
      VN_INFO (result)->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->result == NULL_TREE);
	  nary->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 if (current_info == optimistic_info)
	{
	  current_info = valid_info;
	  vn_nary_op_insert_stmt (new_stmt, result);
	  current_info = optimistic_info;
	}
      else
	vn_nary_op_insert_stmt (new_stmt, result);
      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 (code_helper rcode, tree type, tree *ops)
{
  return vn_nary_build_or_lookup_1 (rcode, type, ops, 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 > 3)
    return NULL_TREE;
  tree ops[3];
  memcpy (ops, nary->op, sizeof (tree) * nary->length);
  return vn_nary_build_or_lookup_1 (nary->opcode, nary->type, ops, false);
}


/* 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 *vr_,
		       bool *disambiguate_only)
{
  vn_reference_t vr = (vn_reference_t)vr_;
  gimple *def_stmt = SSA_NAME_DEF_STMT (vuse);
  tree base = ao_ref_base (ref);
  HOST_WIDE_INT offseti, maxsizei;
  static vec<vn_reference_op_s> lhs_ops;
  ao_ref lhs_ref;
  bool lhs_ref_ok = false;
  poly_int64 copy_size;

  /* If the reference is based on a parameter that was determined as
     pointing to readonly memory it doesn't change.  */
  if (TREE_CODE (base) == MEM_REF
      && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME
      && SSA_NAME_IS_DEFAULT_DEF (TREE_OPERAND (base, 0))
      && bitmap_bit_p (const_parms,
		       SSA_NAME_VERSION (TREE_OPERAND (base, 0))))
    {
      *disambiguate_only = true;
      return NULL;
    }

  /* 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);
      copy_reference_ops_from_ref (lhs, &lhs_ops);
      lhs_ops = valueize_refs_1 (lhs_ops, &valueized_anything);
      if (valueized_anything)
	{
	  lhs_ref_ok = ao_ref_init_from_vn_reference (&lhs_ref,
						      get_alias_set (lhs),
						      TREE_TYPE (lhs), lhs_ops);
	  if (lhs_ref_ok
	      && !refs_may_alias_p_1 (ref, &lhs_ref, true))
	    {
	      *disambiguate_only = true;
	      return NULL;
	    }
	}
      else
	{
	  ao_ref_init (&lhs_ref, lhs);
	  lhs_ref_ok = true;
	}

      /* 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.
	 Note that we don't need to worry about partial overlapping
	 accesses as we then can use TBAA to disambiguate against the
	 clobbering statement when looking up a load (thus the
	 VN_WALKREWRITE guard).  */
      if (vn_walk_kind == VN_WALKREWRITE
	  && is_gimple_reg_type (TREE_TYPE (lhs))
	  && types_compatible_p (TREE_TYPE (lhs), vr->type))
	{
	  tree *saved_last_vuse_ptr = last_vuse_ptr;
	  /* Do not update last_vuse_ptr in vn_reference_lookup_2.  */
	  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), 0, vr);
	  /* Need to restore vr->vuse and vr->hashcode.  */
	  vr->vuse = saved_vuse;
	  vr->hashcode = saved_hashcode;
	  last_vuse_ptr = saved_last_vuse_ptr;
	  if (res && res != (void *)-1)
	    {
	      vn_reference_t vnresult = (vn_reference_t) res;
	      if (vnresult->result
		  && operand_equal_p (vnresult->result,
				      gimple_assign_rhs1 (def_stmt), 0))
		return res;
	    }
	}
    }
  else if (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);
	  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 = true;
	      return NULL;
	    }
	}
    }

  if (*disambiguate_only)
    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;

  /* We can't deduce anything useful from clobbers.  */
  if (gimple_clobber_p (def_stmt))
    return (void *)-1;

  /* 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)
      && integer_zerop (gimple_call_arg (def_stmt, 1))
      && poly_int_tree_p (gimple_call_arg (def_stmt, 2))
      && TREE_CODE (gimple_call_arg (def_stmt, 0)) == ADDR_EXPR)
    {
      tree ref2 = TREE_OPERAND (gimple_call_arg (def_stmt, 0), 0);
      tree base2;
      poly_int64 offset2, size2, maxsize2;
      bool reverse;
      base2 = get_ref_base_and_extent (ref2, &offset2, &size2, &maxsize2,
				       &reverse);
      tree len = gimple_call_arg (def_stmt, 2);
      if (known_size_p (maxsize2)
	  && operand_equal_p (base, base2, 0)
	  && known_subrange_p (offset, maxsize, offset2,
			       wi::to_poly_offset (len) << LOG2_BITS_PER_UNIT))
	{
	  tree val = build_zero_cst (vr->type);
	  return vn_reference_lookup_or_insert_for_pieces
	           (vuse, vr->set, vr->type, vr->operands, val);
	}
    }

  /* 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;
      bool reverse;
      base2 = get_ref_base_and_extent (gimple_assign_lhs (def_stmt),
				       &offset2, &size2, &maxsize2, &reverse);
      if (known_size_p (maxsize2)
	  && operand_equal_p (base, base2, 0)
	  && known_subrange_p (offset, maxsize, offset2, size2))
	{
	  tree val = build_zero_cst (vr->type);
	  return vn_reference_lookup_or_insert_for_pieces
	           (vuse, vr->set, vr->type, vr->operands, val);
	}
    }

  /* 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)
	   && !contains_storage_order_barrier_p (vr->operands)
	   && gimple_assign_single_p (def_stmt)
	   && CHAR_BIT == 8 && BITS_PER_UNIT == 8
	   /* native_encode and native_decode operate on arrays of bytes
	      and so fundamentally need a compile-time size and offset.  */
	   && maxsize.is_constant (&maxsizei)
	   && maxsizei % BITS_PER_UNIT == 0
	   && offset.is_constant (&offseti)
	   && offseti % BITS_PER_UNIT == 0
	   && (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 base2;
      HOST_WIDE_INT offset2, size2;
      bool reverse;
      base2 = get_ref_base_and_extent_hwi (gimple_assign_lhs (def_stmt),
					   &offset2, &size2, &reverse);
      if (base2
	  && !reverse
	  && size2 % BITS_PER_UNIT == 0
	  && offset2 % BITS_PER_UNIT == 0
	  && operand_equal_p (base, base2, 0)
	  && known_subrange_p (offseti, maxsizei, offset2, size2))
	{
	  /* We support up to 512-bit values (for V8DFmode).  */
	  unsigned char buffer[64];
	  int len;

	  tree rhs = gimple_assign_rhs1 (def_stmt);
	  if (TREE_CODE (rhs) == SSA_NAME)
	    rhs = SSA_VAL (rhs);
	  len = native_encode_expr (gimple_assign_rhs1 (def_stmt),
				    buffer, sizeof (buffer),
				    (offseti - offset2) / BITS_PER_UNIT);
	  if (len > 0 && len * BITS_PER_UNIT >= maxsizei)
	    {
	      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 = native_interpret_expr (type, buffer,
						maxsizei / BITS_PER_UNIT);
	      /* 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)
		return vn_reference_lookup_or_insert_for_pieces
			 (vuse, vr->set, vr->type, vr->operands, val);
	    }
	}
    }

  /* 4) Assignment from an SSA name which definition we may be able
     to access pieces from.  */
  else if (known_eq (ref->size, maxsize)
	   && is_gimple_reg_type (vr->type)
	   && !contains_storage_order_barrier_p (vr->operands)
	   && gimple_assign_single_p (def_stmt)
	   && TREE_CODE (gimple_assign_rhs1 (def_stmt)) == SSA_NAME)
    {
      tree base2;
      poly_int64 offset2, size2, maxsize2;
      bool reverse;
      base2 = get_ref_base_and_extent (gimple_assign_lhs (def_stmt),
				       &offset2, &size2, &maxsize2,
				       &reverse);
      if (!reverse
	  && known_size_p (maxsize2)
	  && known_eq (maxsize2, size2)
	  && operand_equal_p (base, base2, 0)
	  && known_subrange_p (offset, maxsize, offset2, size2)
	  /* ???  We can't handle bitfield precision extracts without
	     either using an alternate type for the BIT_FIELD_REF and
	     then doing a conversion or possibly adjusting the offset
	     according to endianness.  */
	  && (! INTEGRAL_TYPE_P (vr->type)
	      || known_eq (ref->size, TYPE_PRECISION (vr->type)))
	  && multiple_p (ref->size, BITS_PER_UNIT))
	{
	  code_helper rcode = BIT_FIELD_REF;
	  tree ops[3];
	  ops[0] = SSA_VAL (gimple_assign_rhs1 (def_stmt));
	  ops[1] = bitsize_int (ref->size);
	  ops[2] = bitsize_int (offset - offset2);
	  tree val = vn_nary_build_or_lookup (rcode, vr->type, ops);
	  if (val
	      && (TREE_CODE (val) != SSA_NAME
		  || ! SSA_NAME_OCCURS_IN_ABNORMAL_PHI (val)))
	    {
	      vn_reference_t res = vn_reference_lookup_or_insert_for_pieces
		  (vuse, vr->set, vr->type, vr->operands, val);
	      return res;
	    }
	}
    }

  /* 5) For aggregate copies translate the reference through them if
     the copy kills ref.  */
  else if (vn_walk_kind == VN_WALKREWRITE
	   && gimple_assign_single_p (def_stmt)
	   && (DECL_P (gimple_assign_rhs1 (def_stmt))
	       || TREE_CODE (gimple_assign_rhs1 (def_stmt)) == MEM_REF
	       || handled_component_p (gimple_assign_rhs1 (def_stmt))))
    {
      tree base2;
      int i, j, k;
      auto_vec<vn_reference_op_s> rhs;
      vn_reference_op_t vro;
      ao_ref r;

      if (!lhs_ref_ok)
	return (void *)-1;

      /* See if the assignment kills REF.  */
      base2 = ao_ref_base (&lhs_ref);
      if (!lhs_ref.max_size_known_p ()
	  || (base != base2
	      && (TREE_CODE (base) != MEM_REF
		  || TREE_CODE (base2) != MEM_REF
		  || TREE_OPERAND (base, 0) != TREE_OPERAND (base2, 0)
		  || !tree_int_cst_equal (TREE_OPERAND (base, 1),
					  TREE_OPERAND (base2, 1))))
	  || !stmt_kills_ref_p (def_stmt, ref))
	return (void *)-1;

      /* Find the common base of ref and the lhs.  lhs_ops already
         contains valueized operands for the lhs.  */
      i = vr->operands.length () - 1;
      j = lhs_ops.length () - 1;
      while (j >= 0 && i >= 0
	     && vn_reference_op_eq (&vr->operands[i], &lhs_ops[j]))
	{
	  i--;
	  j--;
	}

      /* ???  The innermost op should always be a MEM_REF and we already
         checked that the assignment to the lhs kills vr.  Thus for
	 aggregate copies using char[] types the vn_reference_op_eq
	 may fail when comparing types for compatibility.  But we really
	 don't care here - further lookups with the rewritten operands
	 will simply fail if we messed up types too badly.  */
      poly_int64 extra_off = 0;
      if (j == 0 && i >= 0
	  && lhs_ops[0].opcode == MEM_REF
	  && maybe_ne (lhs_ops[0].off, -1))
	{
	  if (known_eq (lhs_ops[0].off, vr->operands[i].off))
	    i--, j--;
	  else if (vr->operands[i].opcode == MEM_REF
		   && maybe_ne (vr->operands[i].off, -1))
	    {
	      extra_off = vr->operands[i].off - lhs_ops[0].off;
	      i--, j--;
	    }
	}

      /* i now points to the first additional op.
	 ???  LHS may not be completely contained in VR, one or more
	 VIEW_CONVERT_EXPRs could be in its way.  We could at least
	 try handling outermost VIEW_CONVERT_EXPRs.  */
      if (j != -1)
	return (void *)-1;

      /* Punt if the additional ops contain a storage order barrier.  */
      for (k = i; k >= 0; k--)
	{
	  vro = &vr->operands[k];
	  if (vro->opcode == VIEW_CONVERT_EXPR && vro->reverse)
	    return (void *)-1;
	}

      /* Now re-write REF to be based on the rhs of the assignment.  */
      copy_reference_ops_from_ref (gimple_assign_rhs1 (def_stmt), &rhs);

      /* Apply an extra offset to the inner MEM_REF of the RHS.  */
      if (maybe_ne (extra_off, 0))
	{
	  if (rhs.length () < 2
	      || rhs[0].opcode != MEM_REF
	      || known_eq (rhs[0].off, -1))
	    return (void *)-1;
	  rhs[0].off += extra_off;
	  rhs[0].op0 = int_const_binop (PLUS_EXPR, rhs[0].op0,
					build_int_cst (TREE_TYPE (rhs[0].op0),
						       extra_off));
	}

      /* We need to pre-pend vr->operands[0..i] to rhs.  */
      vec<vn_reference_op_s> old = vr->operands;
      if (i + 1 + rhs.length () > vr->operands.length ())
	vr->operands.safe_grow (i + 1 + rhs.length ());
      else
	vr->operands.truncate (i + 1 + rhs.length ());
      FOR_EACH_VEC_ELT (rhs, j, vro)
	vr->operands[i + 1 + j] = *vro;
      vr->operands = valueize_refs (vr->operands);
      if (old == shared_lookup_references)
	shared_lookup_references = vr->operands;
      vr->hashcode = vn_reference_compute_hash (vr);

      /* Try folding the new reference to a constant.  */
      tree val = fully_constant_vn_reference_p (vr);
      if (val)
	return vn_reference_lookup_or_insert_for_pieces
		 (vuse, vr->set, vr->type, vr->operands, val);

      /* Adjust *ref from the new operands.  */
      if (!ao_ref_init_from_vn_reference (&r, vr->set, vr->type, vr->operands))
	return (void *)-1;
      /* This can happen with bitfields.  */
      if (maybe_ne (ref->size, r.size))
	return (void *)-1;
      *ref = r;

      /* Do not update last seen VUSE after translating.  */
      last_vuse_ptr = NULL;

      /* Keep looking for the adjusted *REF / VR pair.  */
      return NULL;
    }

  /* 6) For memcpy copies translate the reference through them if
     the copy kills ref.  */
  else if (vn_walk_kind == VN_WALKREWRITE
	   && is_gimple_reg_type (vr->type)
	   /* ???  Handle BCOPY as well.  */
	   && (gimple_call_builtin_p (def_stmt, BUILT_IN_MEMCPY)
	       || gimple_call_builtin_p (def_stmt, BUILT_IN_MEMPCPY)
	       || gimple_call_builtin_p (def_stmt, BUILT_IN_MEMMOVE))
	   && (TREE_CODE (gimple_call_arg (def_stmt, 0)) == ADDR_EXPR
	       || TREE_CODE (gimple_call_arg (def_stmt, 0)) == SSA_NAME)
	   && (TREE_CODE (gimple_call_arg (def_stmt, 1)) == ADDR_EXPR
	       || TREE_CODE (gimple_call_arg (def_stmt, 1)) == SSA_NAME)
	   && poly_int_tree_p (gimple_call_arg (def_stmt, 2), &copy_size))
    {
      tree lhs, rhs;
      ao_ref r;
      poly_int64 rhs_offset, lhs_offset;
      vn_reference_op_s op;
      poly_uint64 mem_offset;
      poly_int64 at, byte_maxsize;

      /* Only handle non-variable, addressable refs.  */
      if (maybe_ne (ref->size, maxsize)
	  || !multiple_p (offset, BITS_PER_UNIT, &at)
	  || !multiple_p (maxsize, BITS_PER_UNIT, &byte_maxsize))
	return (void *)-1;

      /* Extract a pointer base and an offset for the destination.  */
      lhs = gimple_call_arg (def_stmt, 0);
      lhs_offset = 0;
      if (TREE_CODE (lhs) == SSA_NAME)
	{
	  lhs = SSA_VAL (lhs);
	  if (TREE_CODE (lhs) == SSA_NAME)
	    {
	      gimple *def_stmt = SSA_NAME_DEF_STMT (lhs);
	      if (gimple_assign_single_p (def_stmt)
		  && gimple_assign_rhs_code (def_stmt) == ADDR_EXPR)
		lhs = gimple_assign_rhs1 (def_stmt);
	    }
	}
      if (TREE_CODE (lhs) == ADDR_EXPR)
	{
	  tree tem = get_addr_base_and_unit_offset (TREE_OPERAND (lhs, 0),
						    &lhs_offset);
	  if (!tem)
	    return (void *)-1;
	  if (TREE_CODE (tem) == MEM_REF
	      && poly_int_tree_p (TREE_OPERAND (tem, 1), &mem_offset))
	    {
	      lhs = TREE_OPERAND (tem, 0);
	      if (TREE_CODE (lhs) == SSA_NAME)
		lhs = SSA_VAL (lhs);
	      lhs_offset += mem_offset;
	    }
	  else if (DECL_P (tem))
	    lhs = build_fold_addr_expr (tem);
	  else
	    return (void *)-1;
	}
      if (TREE_CODE (lhs) != SSA_NAME
	  && TREE_CODE (lhs) != ADDR_EXPR)
	return (void *)-1;

      /* Extract a pointer base and an offset for the source.  */
      rhs = gimple_call_arg (def_stmt, 1);
      rhs_offset = 0;
      if (TREE_CODE (rhs) == SSA_NAME)
	rhs = SSA_VAL (rhs);
      if (TREE_CODE (rhs) == ADDR_EXPR)
	{
	  tree tem = get_addr_base_and_unit_offset (TREE_OPERAND (rhs, 0),
						    &rhs_offset);
	  if (!tem)
	    return (void *)-1;
	  if (TREE_CODE (tem) == MEM_REF
	      && poly_int_tree_p (TREE_OPERAND (tem, 1), &mem_offset))
	    {
	      rhs = TREE_OPERAND (tem, 0);
	      rhs_offset += mem_offset;
	    }
	  else if (DECL_P (tem)
		   || TREE_CODE (tem) == STRING_CST)
	    rhs = build_fold_addr_expr (tem);
	  else
	    return (void *)-1;
	}
      if (TREE_CODE (rhs) != SSA_NAME
	  && TREE_CODE (rhs) != ADDR_EXPR)
	return (void *)-1;

      /* The bases of the destination and the references have to agree.  */
      if (TREE_CODE (base) == MEM_REF)
	{
	  if (TREE_OPERAND (base, 0) != lhs
	      || !poly_int_tree_p (TREE_OPERAND (base, 1), &mem_offset))
	    return (void *) -1;
	  at += mem_offset;
	}
      else if (!DECL_P (base)
	       || TREE_CODE (lhs) != ADDR_EXPR
	       || TREE_OPERAND (lhs, 0) != base)
	return (void *)-1;

      /* If the access is completely outside of the memcpy destination
	 area there is no aliasing.  */
      if (!ranges_maybe_overlap_p (lhs_offset, copy_size, at, byte_maxsize))
	return NULL;
      /* And the access has to be contained within the memcpy destination.  */
      if (!known_subrange_p (at, byte_maxsize, lhs_offset, copy_size))
	return (void *)-1;

      /* Make room for 2 operands in the new reference.  */
      if (vr->operands.length () < 2)
	{
	  vec<vn_reference_op_s> old = vr->operands;
	  vr->operands.safe_grow_cleared (2);
	  if (old == shared_lookup_references)
	    shared_lookup_references = vr->operands;
	}
      else
	vr->operands.truncate (2);

      /* The looked-through reference is a simple MEM_REF.  */
      memset (&op, 0, sizeof (op));
      op.type = vr->type;
      op.opcode = MEM_REF;
      op.op0 = build_int_cst (ptr_type_node, at - lhs_offset + rhs_offset);
      op.off = at - lhs_offset + rhs_offset;
      vr->operands[0] = op;
      op.type = TREE_TYPE (rhs);
      op.opcode = TREE_CODE (rhs);
      op.op0 = rhs;
      op.off = -1;
      vr->operands[1] = op;
      vr->hashcode = vn_reference_compute_hash (vr);

      /* Try folding the new reference to a constant.  */
      tree val = fully_constant_vn_reference_p (vr);
      if (val)
	return vn_reference_lookup_or_insert_for_pieces
		 (vuse, vr->set, vr->type, vr->operands, val);

      /* Adjust *ref from the new operands.  */
      if (!ao_ref_init_from_vn_reference (&r, vr->set, vr->type, vr->operands))
	return (void *)-1;
      /* This can happen with bitfields.  */
      if (maybe_ne (ref->size, r.size))
	return (void *)-1;
      *ref = r;

      /* Do not update last seen VUSE after translating.  */
      last_vuse_ptr = NULL;

      /* Keep looking for the adjusted *REF / VR pair.  */
      return NULL;
    }

  /* Bail out and stop walking.  */
  return (void *)-1;
}

/* Return a reference op vector from OP that can be used for
   vn_reference_lookup_pieces.  The caller is responsible for releasing
   the vector.  */

vec<vn_reference_op_s>
vn_reference_operands_for_lookup (tree op)
{
  bool valueized;
  return valueize_shared_reference_ops_from_ref (op, &valueized).copy ();
}

/* Lookup a reference operation by it's parts, 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.  */

tree
vn_reference_lookup_pieces (tree vuse, alias_set_type set, tree type,
			    vec<vn_reference_op_s> operands,
			    vn_reference_t *vnresult, vn_lookup_kind kind)
{
  struct vn_reference_s vr1;
  vn_reference_t tmp;
  tree cst;

  if (!vnresult)
    vnresult = &tmp;
  *vnresult = NULL;

  vr1.vuse = vuse_ssa_val (vuse);
  shared_lookup_references.truncate (0);
  shared_lookup_references.safe_grow (operands.length ());
  memcpy (shared_lookup_references.address (),
	  operands.address (),
	  sizeof (vn_reference_op_s)
	  * operands.length ());
  vr1.operands = operands = shared_lookup_references
    = valueize_refs (shared_lookup_references);
  vr1.type = type;
  vr1.set = set;
  vr1.hashcode = vn_reference_compute_hash (&vr1);
  if ((cst = fully_constant_vn_reference_p (&vr1)))
    return cst;

  vn_reference_lookup_1 (&vr1, vnresult);
  if (!*vnresult
      && kind != VN_NOWALK
      && vr1.vuse)
    {
      ao_ref r;
      vn_walk_kind = kind;
      if (ao_ref_init_from_vn_reference (&r, set, type, vr1.operands))
	*vnresult =
	  (vn_reference_t)walk_non_aliased_vuses (&r, vr1.vuse,
						  vn_reference_lookup_2,
						  vn_reference_lookup_3,
						  vuse_ssa_val, &vr1);
      gcc_checking_assert (vr1.operands == shared_lookup_references);
    }

  if (*vnresult)
     return (*vnresult)->result;

  return NULL_TREE;
}

/* Lookup OP in the current hash table, and return the resulting value
   number if it exists in the hash table.  Return NULL_TREE if it does
   not exist in the hash table or if the result field of the structure
   was NULL..  VNRESULT will be filled in with the vn_reference_t
   stored in the hashtable if one exists.  When TBAA_P is false assume
   we are looking up a store and treat it as having alias-set zero.  */

tree
vn_reference_lookup (tree op, tree vuse, vn_lookup_kind kind,
		     vn_reference_t *vnresult, bool tbaa_p)
{
  vec<vn_reference_op_s> operands;
  struct vn_reference_s vr1;
  tree cst;
  bool valuezied_anything;

  if (vnresult)
    *vnresult = NULL;

  vr1.vuse = vuse_ssa_val (vuse);
  vr1.operands = operands
    = valueize_shared_reference_ops_from_ref (op, &valuezied_anything);
  vr1.type = TREE_TYPE (op);
  vr1.set = tbaa_p ? get_alias_set (op) : 0;
  vr1.hashcode = vn_reference_compute_hash (&vr1);
  if ((cst = fully_constant_vn_reference_p (&vr1)))
    return cst;

  if (kind != VN_NOWALK
      && vr1.vuse)
    {
      vn_reference_t wvnresult;
      ao_ref r;
      /* Make sure to use a valueized reference if we valueized anything.
         Otherwise preserve the full reference for advanced TBAA.  */
      if (!valuezied_anything
	  || !ao_ref_init_from_vn_reference (&r, vr1.set, vr1.type,
					     vr1.operands))
	ao_ref_init (&r, op);
      if (! tbaa_p)
	r.ref_alias_set = r.base_alias_set = 0;
      vn_walk_kind = kind;
      wvnresult =
	(vn_reference_t)walk_non_aliased_vuses (&r, vr1.vuse,
						vn_reference_lookup_2,
						vn_reference_lookup_3,
						vuse_ssa_val, &vr1);
      gcc_checking_assert (vr1.operands == shared_lookup_references);
      if (wvnresult)
	{
	  if (vnresult)
	    *vnresult = wvnresult;
	  return wvnresult->result;
	}

      return NULL_TREE;
    }

  return vn_reference_lookup_1 (&vr1, vnresult);
}

/* Lookup CALL in the current hash table and return the entry in
   *VNRESULT if found.  Populates *VR for the hashtable lookup.  */

void
vn_reference_lookup_call (gcall *call, vn_reference_t *vnresult,
			  vn_reference_t vr)
{
  if (vnresult)
    *vnresult = NULL;

  tree vuse = gimple_vuse (call);

  vr->vuse = vuse ? SSA_VAL (vuse) : NULL_TREE;
  vr->operands = valueize_shared_reference_ops_from_call (call);
  vr->type = gimple_expr_type (call);
  vr->set = 0;
  vr->hashcode = vn_reference_compute_hash (vr);
  vn_reference_lookup_1 (vr, vnresult);
}

/* Insert OP into the current hash table with a value number of
   RESULT, and return the resulting reference structure we created.  */

static vn_reference_t
vn_reference_insert (tree op, tree result, tree vuse, tree vdef)
{
  vn_reference_s **slot;
  vn_reference_t vr1;
  bool tem;

  vr1 = current_info->references_pool->allocate ();
  if (TREE_CODE (result) == SSA_NAME)
    vr1->value_id = VN_INFO (result)->value_id;
  else
    vr1->value_id = get_or_alloc_constant_value_id (result);
  vr1->vuse = vuse ? SSA_VAL (vuse) : NULL_TREE;
  vr1->operands = valueize_shared_reference_ops_from_ref (op, &tem).copy ();
  vr1->type = TREE_TYPE (op);
  vr1->set = get_alias_set (op);
  vr1->hashcode = vn_reference_compute_hash (vr1);
  vr1->result = TREE_CODE (result) == SSA_NAME ? SSA_VAL (result) : result;
  vr1->result_vdef = vdef;

  slot = current_info->references->find_slot_with_hash (vr1, vr1->hashcode,
							INSERT);

  /* Because we lookup stores using vuses, and value number failures
     using the vdefs (see visit_reference_op_store for how and why),
     it's possible that on failure we may try to insert an already
     inserted store.  This is not wrong, there is no ssa name for a
     store that we could use as a differentiator anyway.  Thus, unlike
     the other lookup functions, you cannot gcc_assert (!*slot)
     here.  */

  /* But free the old slot in case of a collision.  */
  if (*slot)
    free_reference (*slot);

  *slot = vr1;
  return vr1;
}

/* Insert a reference by it's pieces into the current hash table with
   a value number of RESULT.  Return the resulting reference
   structure we created.  */

vn_reference_t
vn_reference_insert_pieces (tree vuse, alias_set_type set, tree type,
			    vec<vn_reference_op_s> operands,
			    tree result, unsigned int value_id)

{
  vn_reference_s **slot;
  vn_reference_t vr1;

  vr1 = current_info->references_pool->allocate ();
  vr1->value_id = value_id;
  vr1->vuse = vuse ? SSA_VAL (vuse) : NULL_TREE;
  vr1->operands = valueize_refs (operands);
  vr1->type = type;
  vr1->set = set;
  vr1->hashcode = vn_reference_compute_hash (vr1);
  if (result && TREE_CODE (result) == SSA_NAME)
    result = SSA_VAL (result);
  vr1->result = result;

  slot = current_info->references->find_slot_with_hash (vr1, vr1->hashcode,
							INSERT);

  /* At this point we should have all the things inserted that we have
     seen before, and we should never try inserting something that
     already exists.  */
  gcc_assert (!*slot);
  if (*slot)
    free_reference (*slot);

  *slot = vr1;
  return vr1;
}

/* Compute and return the hash value for nary operation VBO1.  */

static hashval_t
vn_nary_op_compute_hash (const vn_nary_op_t vno1)
{
  inchash::hash hstate;
  unsigned i;

  for (i = 0; i < vno1->length; ++i)
    if (TREE_CODE (vno1->op[i]) == SSA_NAME)
      vno1->op[i] = SSA_VAL (vno1->op[i]);

  if (((vno1->length == 2
	&& commutative_tree_code (vno1->opcode))
       || (vno1->length == 3
	   && commutative_ternary_tree_code (vno1->opcode)))
      && tree_swap_operands_p (vno1->op[0], vno1->op[1]))
    std::swap (vno1->op[0], vno1->op[1]);
  else if (TREE_CODE_CLASS (vno1->opcode) == tcc_comparison
	   && tree_swap_operands_p (vno1->op[0], vno1->op[1]))
    {
      std::swap (vno1->op[0], vno1->op[1]);
      vno1->opcode = swap_tree_comparison  (vno1->opcode);
    }

  hstate.add_int (vno1->opcode);
  for (i = 0; i < vno1->length; ++i)
    inchash::add_expr (vno1->op[i], hstate);

  return hstate.end ();
}

/* Compare nary operations VNO1 and VNO2 and return true if they are
   equivalent.  */

bool
vn_nary_op_eq (const_vn_nary_op_t const vno1, const_vn_nary_op_t const vno2)
{
  unsigned i;

  if (vno1->hashcode != vno2->hashcode)
    return false;

  if (vno1->length != vno2->length)
    return false;

  if (vno1->opcode != vno2->opcode
      || !types_compatible_p (vno1->type, vno2->type))
    return false;

  for (i = 0; i < vno1->length; ++i)
    if (!expressions_equal_p (vno1->op[i], vno2->op[i]))
      return false;

  /* BIT_INSERT_EXPR has an implict operand as the type precision
     of op1.  Need to check to make sure they are the same.  */
  if (vno1->opcode == BIT_INSERT_EXPR
      && TREE_CODE (vno1->op[1]) == INTEGER_CST
      && TYPE_PRECISION (TREE_TYPE (vno1->op[1]))
	 != TYPE_PRECISION (TREE_TYPE (vno2->op[1])))
    return false;

  return true;
}

/* Initialize VNO from the pieces provided.  */

static void
init_vn_nary_op_from_pieces (vn_nary_op_t vno, unsigned int length,
			     enum tree_code code, tree type, tree *ops)
{
  vno->opcode = code;
  vno->length = length;
  vno->type = type;
  memcpy (&vno->op[0], ops, sizeof (tree) * length);
}

/* Initialize VNO from OP.  */

static void
init_vn_nary_op_from_op (vn_nary_op_t vno, tree op)
{
  unsigned i;

  vno->opcode = TREE_CODE (op);
  vno->length = TREE_CODE_LENGTH (TREE_CODE (op));
  vno->type = TREE_TYPE (op);
  for (i = 0; i < vno->length; ++i)
    vno->op[i] = TREE_OPERAND (op, i);
}

/* Return the number of operands for a vn_nary ops structure from STMT.  */

static unsigned int
vn_nary_length_from_stmt (gimple *stmt)
{
  switch (gimple_assign_rhs_code (stmt))
    {
    case REALPART_EXPR:
    case IMAGPART_EXPR:
    case VIEW_CONVERT_EXPR:
      return 1;

    case BIT_FIELD_REF:
      return 3;

    case CONSTRUCTOR:
      return CONSTRUCTOR_NELTS (gimple_assign_rhs1 (stmt));

    default:
      return gimple_num_ops (stmt) - 1;
    }
}

/* Initialize VNO from STMT.  */

static void
init_vn_nary_op_from_stmt (vn_nary_op_t vno, gimple *stmt)
{
  unsigned i;

  vno->opcode = gimple_assign_rhs_code (stmt);
  vno->type = gimple_expr_type (stmt);
  switch (vno->opcode)
    {
    case REALPART_EXPR:
    case IMAGPART_EXPR:
    case VIEW_CONVERT_EXPR:
      vno->length = 1;
      vno->op[0] = TREE_OPERAND (gimple_assign_rhs1 (stmt), 0);
      break;

    case BIT_FIELD_REF:
      vno->length = 3;
      vno->op[0] = TREE_OPERAND (gimple_assign_rhs1 (stmt), 0);
      vno->op[1] = TREE_OPERAND (gimple_assign_rhs1 (stmt), 1);
      vno->op[2] = TREE_OPERAND (gimple_assign_rhs1 (stmt), 2);
      break;

    case CONSTRUCTOR:
      vno->length = CONSTRUCTOR_NELTS (gimple_assign_rhs1 (stmt));
      for (i = 0; i < vno->length; ++i)
	vno->op[i] = CONSTRUCTOR_ELT (gimple_assign_rhs1 (stmt), i)->value;
      break;

    default:
      gcc_checking_assert (!gimple_assign_single_p (stmt));
      vno->length = gimple_num_ops (stmt) - 1;
      for (i = 0; i < vno->length; ++i)
	vno->op[i] = gimple_op (stmt, i + 1);
    }
}

/* Compute the hashcode for VNO and look for it in the hash table;
   return the resulting value number if it exists in the hash table.
   Return NULL_TREE if it does not exist in the hash table or if the
   result field of the operation is NULL.  VNRESULT will contain the
   vn_nary_op_t from the hashtable if it exists.  */

static tree
vn_nary_op_lookup_1 (vn_nary_op_t vno, vn_nary_op_t *vnresult)
{
  vn_nary_op_s **slot;

  if (vnresult)
    *vnresult = NULL;

  vno->hashcode = vn_nary_op_compute_hash (vno);
  slot = current_info->nary->find_slot_with_hash (vno, vno->hashcode,
						  NO_INSERT);
  if (!slot && current_info == optimistic_info)
    slot = valid_info->nary->find_slot_with_hash (vno, vno->hashcode,
						  NO_INSERT);
  if (!slot)
    return NULL_TREE;
  if (vnresult)
    *vnresult = *slot;
  return (*slot)->result;
}

/* Lookup a n-ary operation by its pieces and return the resulting value
   number if it exists in the hash table.  Return NULL_TREE if it does
   not exist in the hash table or if the result field of the operation
   is NULL. VNRESULT will contain the vn_nary_op_t from the hashtable
   if it exists.  */

tree
vn_nary_op_lookup_pieces (unsigned int length, enum tree_code code,
			  tree type, tree *ops, vn_nary_op_t *vnresult)
{
  vn_nary_op_t vno1 = XALLOCAVAR (struct vn_nary_op_s,
				  sizeof_vn_nary_op (length));
  init_vn_nary_op_from_pieces (vno1, length, code, type, ops);
  return vn_nary_op_lookup_1 (vno1, vnresult);
}

/* Lookup OP in the current hash table, and return the resulting value
   number if it exists in the hash table.  Return NULL_TREE if it does
   not exist in the hash table or if the result field of the operation
   is NULL. VNRESULT will contain the vn_nary_op_t from the hashtable
   if it exists.  */

tree
vn_nary_op_lookup (tree op, vn_nary_op_t *vnresult)
{
  vn_nary_op_t vno1
    = XALLOCAVAR (struct vn_nary_op_s,
		  sizeof_vn_nary_op (TREE_CODE_LENGTH (TREE_CODE (op))));
  init_vn_nary_op_from_op (vno1, op);
  return vn_nary_op_lookup_1 (vno1, vnresult);
}

/* Lookup the rhs of STMT in the current hash table, and return the resulting
   value number if it exists in the hash table.  Return NULL_TREE if
   it does not exist in the hash table.  VNRESULT will contain the
   vn_nary_op_t from the hashtable if it exists.  */

tree
vn_nary_op_lookup_stmt (gimple *stmt, vn_nary_op_t *vnresult)
{
  vn_nary_op_t vno1
    = XALLOCAVAR (struct vn_nary_op_s,
		  sizeof_vn_nary_op (vn_nary_length_from_stmt (stmt)));
  init_vn_nary_op_from_stmt (vno1, stmt);
  return vn_nary_op_lookup_1 (vno1, vnresult);
}

/* Allocate a vn_nary_op_t with LENGTH operands on STACK.  */

static vn_nary_op_t
alloc_vn_nary_op_noinit (unsigned int length, struct obstack *stack)
{
  return (vn_nary_op_t) obstack_alloc (stack, sizeof_vn_nary_op (length));
}

/* Allocate and initialize a vn_nary_op_t on CURRENT_INFO's
   obstack.  */

static vn_nary_op_t
alloc_vn_nary_op (unsigned int length, tree result, unsigned int value_id)
{
  vn_nary_op_t vno1 = alloc_vn_nary_op_noinit (length,
					       &current_info->nary_obstack);

  vno1->value_id = value_id;
  vno1->length = length;
  vno1->result = result;

  return vno1;
}

/* Insert VNO into TABLE.  If COMPUTE_HASH is true, then compute
   VNO->HASHCODE first.  */

static vn_nary_op_t
vn_nary_op_insert_into (vn_nary_op_t vno, vn_nary_op_table_type *table,
			bool compute_hash)
{
  vn_nary_op_s **slot;

  if (compute_hash)
    vno->hashcode = vn_nary_op_compute_hash (vno);

  slot = table->find_slot_with_hash (vno, vno->hashcode, INSERT);
  /* While we do not want to insert things twice it's awkward to
     avoid it in the case where visit_nary_op pattern-matches stuff
     and ends up simplifying the replacement to itself.  We then
     get two inserts, one from visit_nary_op and one from
     vn_nary_build_or_lookup.
     So allow inserts with the same value number.  */
  if (*slot && (*slot)->result == vno->result)
    return *slot;

  gcc_assert (!*slot);

  *slot = vno;
  return vno;
}

/* Insert a n-ary operation into the current hash table using it's
   pieces.  Return the vn_nary_op_t structure we created and put in
   the hashtable.  */

vn_nary_op_t
vn_nary_op_insert_pieces (unsigned int length, enum tree_code code,
			  tree type, tree *ops,
			  tree result, unsigned int value_id)
{
  vn_nary_op_t vno1 = alloc_vn_nary_op (length, result, value_id);
  init_vn_nary_op_from_pieces (vno1, length, code, type, ops);
  return vn_nary_op_insert_into (vno1, current_info->nary, true);
}

/* Insert OP into the current hash table with a value number of
   RESULT.  Return the vn_nary_op_t structure we created and put in
   the hashtable.  */

vn_nary_op_t
vn_nary_op_insert (tree op, tree result)
{
  unsigned length = TREE_CODE_LENGTH (TREE_CODE (op));
  vn_nary_op_t vno1;

  vno1 = alloc_vn_nary_op (length, result, VN_INFO (result)->value_id);
  init_vn_nary_op_from_op (vno1, op);
  return vn_nary_op_insert_into (vno1, current_info->nary, true);
}

/* Insert the rhs of STMT into the current hash table with a value number of
   RESULT.  */

static vn_nary_op_t
vn_nary_op_insert_stmt (gimple *stmt, tree result)
{
  vn_nary_op_t vno1
    = alloc_vn_nary_op (vn_nary_length_from_stmt (stmt),
			result, VN_INFO (result)->value_id);
  init_vn_nary_op_from_stmt (vno1, stmt);
  return vn_nary_op_insert_into (vno1, current_info->nary, true);
}

/* Compute a hashcode for PHI operation VP1 and return it.  */

static inline hashval_t
vn_phi_compute_hash (vn_phi_t vp1)
{
  inchash::hash hstate (vp1->phiargs.length () > 2
			? vp1->block->index : vp1->phiargs.length ());
  tree phi1op;
  tree type;
  edge e;
  edge_iterator ei;

  /* If all PHI arguments are constants we need to distinguish
     the PHI node via its type.  */
  type = vp1->type;
  hstate.merge_hash (vn_hash_type (type));

  FOR_EACH_EDGE (e, ei, vp1->block->preds)
    {
      /* Don't hash backedge values they need to be handled as VN_TOP
         for optimistic value-numbering.  */
      if (e->flags & EDGE_DFS_BACK)
	continue;

      phi1op = vp1->phiargs[e->dest_idx];
      if (phi1op == VN_TOP)
	continue;
      inchash::add_expr (phi1op, hstate);
    }

  return hstate.end ();
}


/* Return true if COND1 and COND2 represent the same condition, set
   *INVERTED_P if one needs to be inverted to make it the same as
   the other.  */

static bool
cond_stmts_equal_p (gcond *cond1, tree lhs1, tree rhs1,
		    gcond *cond2, tree lhs2, tree rhs2, bool *inverted_p)
{
  enum tree_code code1 = gimple_cond_code (cond1);
  enum tree_code code2 = gimple_cond_code (cond2);

  *inverted_p = false;
  if (code1 == code2)
    ;
  else if (code1 == swap_tree_comparison (code2))
    std::swap (lhs2, rhs2);
  else if (code1 == invert_tree_comparison (code2, HONOR_NANS (lhs2)))
    *inverted_p = true;
  else if (code1 == invert_tree_comparison
	   	      (swap_tree_comparison (code2), HONOR_NANS (lhs2)))
    {
      std::swap (lhs2, rhs2);
      *inverted_p = true;
    }
  else
    return false;

  return ((expressions_equal_p (lhs1, lhs2)
	   && expressions_equal_p (rhs1, rhs2))
	  || (commutative_tree_code (code1)
	      && expressions_equal_p (lhs1, rhs2)
	      && expressions_equal_p (rhs1, lhs2)));
}

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

static int
vn_phi_eq (const_vn_phi_t const vp1, const_vn_phi_t const vp2)
{
  if (vp1->hashcode != vp2->hashcode)
    return false;

  if (vp1->block != vp2->block)
    {
      if (vp1->phiargs.length () != vp2->phiargs.length ())
	return false;

      switch (vp1->phiargs.length ())
	{
	case 1:
	  /* Single-arg PHIs are just copies.  */
	  break;

	case 2:
	  {
	    /* Rule out backedges into the PHI.  */
	    if (vp1->block->loop_father->header == vp1->block
		|| vp2->block->loop_father->header == vp2->block)
	      return false;

	    /* If the PHI nodes do not have compatible types
	       they are not the same.  */
	    if (!types_compatible_p (vp1->type, vp2->type))
	      return false;

	    basic_block idom1
	      = get_immediate_dominator (CDI_DOMINATORS, vp1->block);
	    basic_block idom2
	      = get_immediate_dominator (CDI_DOMINATORS, vp2->block);
	    /* If the immediate dominator end in switch stmts multiple