On Wed, 30 Sep 2015, Richard Biener wrote:

> 
> This is the last patch in the series and it finally ditches the
> stmt combining code from SCCVN which uses GENERIC.  I've been sitting
> on this for a while because of the "bad" interface that new mprts_hook
> is but I couldn't think of a better way than completely refactoring
> stmt folding into more C++ (and I'm not even sure how that end result
> would look like).  So rather than pondering on this forever the following
> patch goes forward.
> 
> Net result is that there will be hopefully no regressions (I know
> about a few corner cases I found with plastering the code with asserts
> but I do not consider them important) but progression both with regarding
> to compile-time / memory-use and optimization (because the new code
> is strictly more powerful, not relying on the has_constants heuristic).
> 
> This is also the last major piece that was sitting on the
> match-and-simplify branch.
> 
> Bootstrapped on x86_64-unknown-linux-gnu, re-testing in progress.

This is the variant I committed.

Richard.

2015-10-01  Richard Biener  <rguent...@suse.de>

        * gimple-match.h (mprts_hook): Declare.
        * gimple-match.head.c (mprts_hook): Define.
        (maybe_push_res_to_seq): Use new hook.
        * gimple-fold.c (gimple_fold_stmt_to_constant_1): Likewise.
        * tree-ssa-sccvn.h (vn_ssa_aux::expr): Change to a gimple_seq.
        (vn_ssa_aux::has_constants): Remove.
        * tree-ssa-sccvn.c: Include gimple-match.h.
        (VN_INFO_GET): Assert we don't re-use SSA names.
        (vn_get_expr_for): Remove.
        (expr_has_constants): Likewise.
        (stmt_has_constants): Likewise.
        (simplify_binary_expression): Likewise.
        (simplify_unary_expression): Likewise.
        (vn_lookup_simplify_result): New hook.
        (visit_copy): Adjust.
        (visit_reference_op_call): Likewise.
        (visit_phi): Likewise.
        (visit_use): Likewise.
        (process_scc): Likewise.
        (init_scc_vn): Likewise.
        (visit_reference_op_load): Likewise.  Use match-and-simplify and
        a gimple seq for inserted expressions.
        (try_to_simplify): Remove GENERIC stmt combining code.
        (sccvn_dom_walker::before_dom_children): Use match-and-simplify.
        * tree-ssa-pre.c (eliminate_insert): Adjust.
        (eliminate_dom_walker::before_dom_children): Likewise.

        * gcc.dg/tree-ssa/ssa-fre-7.c: Adjust.
        * gcc.dg/tree-ssa/ssa-fre-8.c: Likewise.

Index: gcc/tree-ssa-sccvn.c
===================================================================
*** gcc/tree-ssa-sccvn.c.orig   2015-09-30 15:00:30.636706575 +0200
--- gcc/tree-ssa-sccvn.c        2015-09-30 15:32:03.543978540 +0200
*************** along with GCC; see the file COPYING3.
*** 58,63 ****
--- 58,64 ----
  #include "domwalk.h"
  #include "cgraph.h"
  #include "gimple-iterator.h"
+ #include "gimple-match.h"
  
  /* This algorithm is based on the SCC algorithm presented by Keith
     Cooper and L. Taylor Simpson in "SCC-Based Value numbering"
*************** VN_INFO_GET (tree name)
*** 401,406 ****
--- 402,409 ----
  {
    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_INFO_GET (tree name)
*** 410,501 ****
  }
  
  
- /* Get the representative expression for the SSA_NAME NAME.  Returns
-    the representative SSA_NAME if there is no expression associated with it.  
*/
- 
- tree
- vn_get_expr_for (tree name)
- {
-   vn_ssa_aux_t vn = VN_INFO (name);
-   gimple *def_stmt;
-   tree expr = NULL_TREE;
-   enum tree_code code;
- 
-   if (vn->valnum == VN_TOP)
-     return name;
- 
-   /* If the value-number is a constant it is the representative
-      expression.  */
-   if (TREE_CODE (vn->valnum) != SSA_NAME)
-     return vn->valnum;
- 
-   /* Get to the information of the value of this SSA_NAME.  */
-   vn = VN_INFO (vn->valnum);
- 
-   /* If the value-number is a constant it is the representative
-      expression.  */
-   if (TREE_CODE (vn->valnum) != SSA_NAME)
-     return vn->valnum;
- 
-   /* Else if we have an expression, return it.  */
-   if (vn->expr != NULL_TREE)
-     return vn->expr;
- 
-   /* Otherwise use the defining statement to build the expression.  */
-   def_stmt = SSA_NAME_DEF_STMT (vn->valnum);
- 
-   /* If the value number is not an assignment use it directly.  */
-   if (!is_gimple_assign (def_stmt))
-     return vn->valnum;
- 
-   /* Note that we can valueize here because we clear the cached
-      simplified expressions after each optimistic iteration.  */
-   code = gimple_assign_rhs_code (def_stmt);
-   switch (TREE_CODE_CLASS (code))
-     {
-     case tcc_reference:
-       if ((code == REALPART_EXPR
-          || code == IMAGPART_EXPR
-          || code == VIEW_CONVERT_EXPR)
-         && TREE_CODE (TREE_OPERAND (gimple_assign_rhs1 (def_stmt),
-                                     0)) == SSA_NAME)
-       expr = fold_build1 (code,
-                           gimple_expr_type (def_stmt),
-                           vn_valueize (TREE_OPERAND
-                                          (gimple_assign_rhs1 (def_stmt), 0)));
-       break;
- 
-     case tcc_unary:
-       expr = fold_build1 (code,
-                         gimple_expr_type (def_stmt),
-                         vn_valueize (gimple_assign_rhs1 (def_stmt)));
-       break;
- 
-     case tcc_binary:
-       expr = fold_build2 (code,
-                         gimple_expr_type (def_stmt),
-                         vn_valueize (gimple_assign_rhs1 (def_stmt)),
-                         vn_valueize (gimple_assign_rhs2 (def_stmt)));
-       break;
- 
-     case tcc_exceptional:
-       if (code == CONSTRUCTOR
-         && TREE_CODE
-              (TREE_TYPE (gimple_assign_rhs1 (def_stmt))) == VECTOR_TYPE)
-       expr = gimple_assign_rhs1 (def_stmt);
-       break;
- 
-     default:;
-     }
-   if (expr == NULL_TREE)
-     return vn->valnum;
- 
-   /* Cache the expression.  */
-   vn->expr = expr;
- 
-   return expr;
- }
- 
  /* Return the vn_kind the expression computed by the stmt should be
     associated with.  */
  
--- 413,418 ----
*************** vn_nary_op_lookup_stmt (gimple *stmt, vn
*** 2685,2690 ****
--- 2602,2619 ----
    return vn_nary_op_lookup_1 (vno1, vnresult);
  }
  
+ /* 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;
+   vn_nary_op_t vnresult = NULL;
+   return vn_nary_op_lookup_pieces (TREE_CODE_LENGTH ((tree_code) rcode),
+                                  (tree_code) rcode, type, ops, &vnresult);
+ }
+ 
  /* Allocate a vn_nary_op_t with LENGTH operands on STACK.  */
  
  static vn_nary_op_t
*************** defs_to_varying (gimple *stmt)
*** 3047,3066 ****
    return changed;
  }
  
- static bool expr_has_constants (tree expr);
- 
  /* Visit a copy between LHS and RHS, return true if the value number
     changed.  */
  
  static bool
  visit_copy (tree lhs, tree rhs)
  {
!   /* The copy may have a more interesting constant filled expression
!      (we don't, since we know our RHS is just an SSA name).  */
!   VN_INFO (lhs)->has_constants = VN_INFO (rhs)->has_constants;
!   VN_INFO (lhs)->expr = VN_INFO (rhs)->expr;
! 
!   /* And finally valueize.  */
    rhs = SSA_VAL (rhs);
  
    return set_ssa_val_to (lhs, rhs);
--- 2976,2988 ----
    return changed;
  }
  
  /* Visit a copy between LHS and RHS, return true if the value number
     changed.  */
  
  static bool
  visit_copy (tree lhs, tree rhs)
  {
!   /* Valueize.  */
    rhs = SSA_VAL (rhs);
  
    return set_ssa_val_to (lhs, rhs);
*************** visit_reference_op_call (tree lhs, gcall
*** 3111,3122 ****
        vnresult->result = lhs;
  
        if (vnresult->result && lhs)
!       {
!         changed |= set_ssa_val_to (lhs, vnresult->result);
! 
!         if (VN_INFO (vnresult->result)->has_constants)
!           VN_INFO (lhs)->has_constants = true;
!       }
      }
    else
      {
--- 3033,3039 ----
        vnresult->result = lhs;
  
        if (vnresult->result && lhs)
!       changed |= set_ssa_val_to (lhs, vnresult->result);
      }
    else
      {
*************** visit_reference_op_load (tree lhs, tree
*** 3172,3204 ****
         of VIEW_CONVERT_EXPR <TREE_TYPE (result)> (result).
         So first simplify and lookup this expression to see if it
         is already available.  */
!       tree val = fold_build1 (VIEW_CONVERT_EXPR, TREE_TYPE (op), result);
!       if ((CONVERT_EXPR_P (val)
!          || TREE_CODE (val) == VIEW_CONVERT_EXPR)
!         && TREE_CODE (TREE_OPERAND (val, 0)) == SSA_NAME)
!         {
!         tree tem = vn_get_expr_for (TREE_OPERAND (val, 0));
!         if ((CONVERT_EXPR_P (tem)
!              || TREE_CODE (tem) == VIEW_CONVERT_EXPR)
!             && (tem = fold_unary_ignore_overflow (TREE_CODE (val),
!                                                   TREE_TYPE (val), tem)))
!           val = tem;
!       }
!       result = val;
!       if (!is_gimple_min_invariant (val)
!         && TREE_CODE (val) != SSA_NAME)
!       result = vn_nary_op_lookup (val, NULL);
!       /* If the expression is not yet available, value-number lhs to
!        a new SSA_NAME we create.  */
!       if (!result)
!         {
!         result = make_temp_ssa_name (TREE_TYPE (lhs), gimple_build_nop (),
!                                      "vntemp");
          /* Initialize value-number information properly.  */
          VN_INFO_GET (result)->valnum = result;
          VN_INFO (result)->value_id = get_next_value_id ();
!         VN_INFO (result)->expr = val;
!         VN_INFO (result)->has_constants = expr_has_constants (val);
          VN_INFO (result)->needs_insertion = true;
          /* As all "inserted" statements are singleton SCCs, insert
             to the valid table.  This is strictly needed to
--- 3089,3126 ----
         of VIEW_CONVERT_EXPR <TREE_TYPE (result)> (result).
         So first simplify and lookup this expression to see if it
         is already available.  */
!       gimple_seq stmts = NULL;
!       mprts_hook = vn_lookup_simplify_result;
!       tree val = gimple_simplify (VIEW_CONVERT_EXPR, TREE_TYPE (op),
!                                 result, &stmts, vn_valueize);
!       mprts_hook = NULL;
!       if (!val)
!       {
!         val = vn_nary_op_lookup_pieces (1, VIEW_CONVERT_EXPR,
!                                         TREE_TYPE (op), &result, NULL);
!         if (!val)
!           {
!             val = make_ssa_name (TREE_TYPE (op));
!             gimple *new_stmt = gimple_build_assign (val, VIEW_CONVERT_EXPR,
!                                                     build1 (VIEW_CONVERT_EXPR,
!                                                             TREE_TYPE (op),
!                                                             result));
!             gimple_seq_add_stmt_without_update (&stmts, new_stmt);
!           }
!       }
!       if (gimple_seq_empty_p (stmts))
!       /* The expression is already available.  */
!       result = val;
!       else
!       {
!         gcc_assert (gimple_seq_singleton_p (stmts));
!         /* The expression is not yet available, value-number lhs to
!            the new SSA_NAME we created.  */
!         result = val;
          /* Initialize value-number information properly.  */
          VN_INFO_GET (result)->valnum = result;
          VN_INFO (result)->value_id = get_next_value_id ();
!         VN_INFO (result)->expr = stmts;
          VN_INFO (result)->needs_insertion = true;
          /* As all "inserted" statements are singleton SCCs, insert
             to the valid table.  This is strictly needed to
*************** visit_reference_op_load (tree lhs, tree
*** 3210,3241 ****
          if (current_info == optimistic_info)
            {
              current_info = valid_info;
!             vn_nary_op_insert (val, result);
              current_info = optimistic_info;
            }
          else
!           vn_nary_op_insert (val, result);
          if (dump_file && (dump_flags & TDF_DETAILS))
            {
              fprintf (dump_file, "Inserting name ");
              print_generic_expr (dump_file, result, 0);
              fprintf (dump_file, " for expression ");
!             print_generic_expr (dump_file, val, 0);
              fprintf (dump_file, "\n");
            }
        }
      }
  
    if (result)
!     {
!       changed = set_ssa_val_to (lhs, result);
!       if (TREE_CODE (result) == SSA_NAME
!         && VN_INFO (result)->has_constants)
!       {
!         VN_INFO (lhs)->expr = VN_INFO (result)->expr;
!         VN_INFO (lhs)->has_constants = true;
!       }
!     }
    else
      {
        changed = set_ssa_val_to (lhs, lhs);
--- 3132,3156 ----
          if (current_info == optimistic_info)
            {
              current_info = valid_info;
!             vn_nary_op_insert_stmt (gimple_seq_first_stmt (stmts), result);
              current_info = optimistic_info;
            }
          else
!           vn_nary_op_insert_stmt (gimple_seq_first_stmt (stmts), result);
          if (dump_file && (dump_flags & TDF_DETAILS))
            {
              fprintf (dump_file, "Inserting name ");
              print_generic_expr (dump_file, result, 0);
              fprintf (dump_file, " for expression ");
!             print_gimple_expr (dump_file, gimple_seq_first_stmt (stmts),
!                                0, TDF_SLIM);
              fprintf (dump_file, "\n");
            }
        }
      }
  
    if (result)
!     changed = set_ssa_val_to (lhs, result);
    else
      {
        changed = set_ssa_val_to (lhs, lhs);
*************** visit_phi (gimple *phi)
*** 3401,3608 ****
    else
      {
        vn_phi_insert (phi, PHI_RESULT (phi));
-       VN_INFO (PHI_RESULT (phi))->has_constants = false;
-       VN_INFO (PHI_RESULT (phi))->expr = PHI_RESULT (phi);
        changed = set_ssa_val_to (PHI_RESULT (phi), PHI_RESULT (phi));
      }
  
    return changed;
  }
  
- /* Return true if EXPR contains constants.  */
- 
- static bool
- expr_has_constants (tree expr)
- {
-   switch (TREE_CODE_CLASS (TREE_CODE (expr)))
-     {
-     case tcc_unary:
-       return is_gimple_min_invariant (TREE_OPERAND (expr, 0));
- 
-     case tcc_binary:
-       return is_gimple_min_invariant (TREE_OPERAND (expr, 0))
-       || is_gimple_min_invariant (TREE_OPERAND (expr, 1));
-       /* Constants inside reference ops are rarely interesting, but
-        it can take a lot of looking to find them.  */
-     case tcc_reference:
-     case tcc_declaration:
-       return false;
-     default:
-       return is_gimple_min_invariant (expr);
-     }
-   return false;
- }
- 
- /* Return true if STMT contains constants.  */
- 
- static bool
- stmt_has_constants (gimple *stmt)
- {
-   tree tem;
- 
-   if (gimple_code (stmt) != GIMPLE_ASSIGN)
-     return false;
- 
-   switch (get_gimple_rhs_class (gimple_assign_rhs_code (stmt)))
-     {
-     case GIMPLE_TERNARY_RHS:
-       tem = gimple_assign_rhs3 (stmt);
-       if (TREE_CODE (tem) == SSA_NAME)
-       tem = SSA_VAL (tem);
-       if (is_gimple_min_invariant (tem))
-       return true;
-       /* Fallthru.  */
- 
-     case GIMPLE_BINARY_RHS:
-       tem = gimple_assign_rhs2 (stmt);
-       if (TREE_CODE (tem) == SSA_NAME)
-       tem = SSA_VAL (tem);
-       if (is_gimple_min_invariant (tem))
-       return true;
-       /* Fallthru.  */
- 
-     case GIMPLE_SINGLE_RHS:
-       /* Constants inside reference ops are rarely interesting, but
-        it can take a lot of looking to find them.  */
-     case GIMPLE_UNARY_RHS:
-       tem = gimple_assign_rhs1 (stmt);
-       if (TREE_CODE (tem) == SSA_NAME)
-       tem = SSA_VAL (tem);
-       return is_gimple_min_invariant (tem);
- 
-     default:
-       gcc_unreachable ();
-     }
-   return false;
- }
- 
- /* Simplify the binary expression RHS, and return the result if
-    simplified. */
- 
- static tree
- simplify_binary_expression (gimple *stmt)
- {
-   tree result = NULL_TREE;
-   tree op0 = gimple_assign_rhs1 (stmt);
-   tree op1 = gimple_assign_rhs2 (stmt);
-   enum tree_code code = gimple_assign_rhs_code (stmt);
- 
-   /* This will not catch every single case we could combine, but will
-      catch those with constants.  The goal here is to simultaneously
-      combine constants between expressions, but avoid infinite
-      expansion of expressions during simplification.  */
-   op0 = vn_valueize (op0);
-   if (TREE_CODE (op0) == SSA_NAME
-       && (VN_INFO (op0)->has_constants
-         || TREE_CODE_CLASS (code) == tcc_comparison
-         || code == COMPLEX_EXPR))
-     op0 = vn_get_expr_for (op0);
- 
-   op1 = vn_valueize (op1);
-   if (TREE_CODE (op1) == SSA_NAME
-       && (VN_INFO (op1)->has_constants
-         || code == COMPLEX_EXPR))
-     op1 = vn_get_expr_for (op1);
- 
-   /* Pointer plus constant can be represented as invariant address.
-      Do so to allow further propatation, see also tree forwprop.  */
-   if (code == POINTER_PLUS_EXPR
-       && tree_fits_uhwi_p (op1)
-       && TREE_CODE (op0) == ADDR_EXPR
-       && is_gimple_min_invariant (op0))
-     return build_invariant_address (TREE_TYPE (op0),
-                                   TREE_OPERAND (op0, 0),
-                                   tree_to_uhwi (op1));
- 
-   /* Avoid folding if nothing changed.  */
-   if (op0 == gimple_assign_rhs1 (stmt)
-       && op1 == gimple_assign_rhs2 (stmt))
-     return NULL_TREE;
- 
-   fold_defer_overflow_warnings ();
- 
-   result = fold_binary (code, gimple_expr_type (stmt), op0, op1);
-   if (result)
-     STRIP_USELESS_TYPE_CONVERSION (result);
- 
-   fold_undefer_overflow_warnings (result && valid_gimple_rhs_p (result),
-                                 stmt, 0);
- 
-   /* Make sure result is not a complex expression consisting
-      of operators of operators (IE (a + b) + (a + c))
-      Otherwise, we will end up with unbounded expressions if
-      fold does anything at all.  */
-   if (result && valid_gimple_rhs_p (result))
-     return result;
- 
-   return NULL_TREE;
- }
- 
- /* Simplify the unary expression RHS, and return the result if
-    simplified. */
- 
- static tree
- simplify_unary_expression (gassign *stmt)
- {
-   tree result = NULL_TREE;
-   tree orig_op0, op0 = gimple_assign_rhs1 (stmt);
-   enum tree_code code = gimple_assign_rhs_code (stmt);
- 
-   /* We handle some tcc_reference codes here that are all
-      GIMPLE_ASSIGN_SINGLE codes.  */
-   if (code == REALPART_EXPR
-       || code == IMAGPART_EXPR
-       || code == VIEW_CONVERT_EXPR
-       || code == BIT_FIELD_REF)
-     op0 = TREE_OPERAND (op0, 0);
- 
-   orig_op0 = op0;
-   op0 = vn_valueize (op0);
-   if (TREE_CODE (op0) == SSA_NAME)
-     {
-       if (VN_INFO (op0)->has_constants)
-       op0 = vn_get_expr_for (op0);
-       else if (CONVERT_EXPR_CODE_P (code)
-              || code == REALPART_EXPR
-              || code == IMAGPART_EXPR
-              || code == VIEW_CONVERT_EXPR
-              || code == BIT_FIELD_REF)
-       {
-         /* We want to do tree-combining on conversion-like expressions.
-            Make sure we feed only SSA_NAMEs or constants to fold though.  */
-         tree tem = vn_get_expr_for (op0);
-         if (UNARY_CLASS_P (tem)
-             || BINARY_CLASS_P (tem)
-             || TREE_CODE (tem) == VIEW_CONVERT_EXPR
-             || TREE_CODE (tem) == SSA_NAME
-             || TREE_CODE (tem) == CONSTRUCTOR
-             || is_gimple_min_invariant (tem))
-           op0 = tem;
-       }
-     }
- 
-   /* Avoid folding if nothing changed, but remember the expression.  */
-   if (op0 == orig_op0)
-     return NULL_TREE;
- 
-   if (code == BIT_FIELD_REF)
-     {
-       tree rhs = gimple_assign_rhs1 (stmt);
-       result = fold_ternary (BIT_FIELD_REF, TREE_TYPE (rhs),
-                            op0, TREE_OPERAND (rhs, 1), TREE_OPERAND (rhs, 2));
-     }
-   else
-     result = fold_unary_ignore_overflow (code, gimple_expr_type (stmt), op0);
-   if (result)
-     {
-       STRIP_USELESS_TYPE_CONVERSION (result);
-       if (valid_gimple_rhs_p (result))
-         return result;
-     }
- 
-   return NULL_TREE;
- }
- 
  /* Try to simplify RHS using equivalences and constant folding.  */
  
  static tree
--- 3316,3327 ----
*************** try_to_simplify (gassign *stmt)
*** 3617,3651 ****
      return NULL_TREE;
  
    /* First try constant folding based on our current lattice.  */
    tem = gimple_fold_stmt_to_constant_1 (stmt, vn_valueize, vn_valueize);
    if (tem
        && (TREE_CODE (tem) == SSA_NAME
          || is_gimple_min_invariant (tem)))
      return tem;
  
-   /* If that didn't work try combining multiple statements.  */
-   switch (TREE_CODE_CLASS (code))
-     {
-     case tcc_reference:
-       /* Fallthrough for some unary codes that can operate on registers.  */
-       if (!(code == REALPART_EXPR
-           || code == IMAGPART_EXPR
-           || code == VIEW_CONVERT_EXPR
-           || code == BIT_FIELD_REF))
-       break;
-       /* We could do a little more with unary ops, if they expand
-        into binary ops, but it's debatable whether it is worth it. */
-     case tcc_unary:
-       return simplify_unary_expression (stmt);
- 
-     case tcc_comparison:
-     case tcc_binary:
-       return simplify_binary_expression (stmt);
- 
-     default:
-       break;
-     }
- 
    return NULL_TREE;
  }
  
--- 3336,3349 ----
      return NULL_TREE;
  
    /* First try constant folding based on our current lattice.  */
+   mprts_hook = vn_lookup_simplify_result;
    tem = gimple_fold_stmt_to_constant_1 (stmt, vn_valueize, vn_valueize);
+   mprts_hook = NULL;
    if (tem
        && (TREE_CODE (tem) == SSA_NAME
          || is_gimple_min_invariant (tem)))
      return tem;
  
    return NULL_TREE;
  }
  
*************** visit_use (tree use)
*** 3703,3713 ****
                  print_gimple_expr (dump_file, stmt, 0, 0);
                  fprintf (dump_file, " simplified to ");
                  print_generic_expr (dump_file, simplified, 0);
!                 if (TREE_CODE (lhs) == SSA_NAME)
!                   fprintf (dump_file, " has constants %d\n",
!                            expr_has_constants (simplified));
!                 else
!                   fprintf (dump_file, "\n");
                }
            }
          /* Setting value numbers to constants will occasionally
--- 3401,3407 ----
                  print_gimple_expr (dump_file, stmt, 0, 0);
                  fprintf (dump_file, " simplified to ");
                  print_generic_expr (dump_file, simplified, 0);
!                 fprintf (dump_file, "\n");
                }
            }
          /* Setting value numbers to constants will occasionally
*************** visit_use (tree use)
*** 3718,3725 ****
              && is_gimple_min_invariant (simplified)
              && TREE_CODE (lhs) == SSA_NAME)
            {
-             VN_INFO (lhs)->expr = simplified;
-             VN_INFO (lhs)->has_constants = true;
              changed = set_ssa_val_to (lhs, simplified);
              goto done;
            }
--- 3412,3417 ----
*************** visit_use (tree use)
*** 3730,3758 ****
              changed = visit_copy (lhs, simplified);
              goto done;
            }
-         else if (simplified)
-           {
-             if (TREE_CODE (lhs) == SSA_NAME)
-               {
-                 VN_INFO (lhs)->has_constants = expr_has_constants 
(simplified);
-                 /* We have to unshare the expression or else
-                    valuizing may change the IL stream.  */
-                 VN_INFO (lhs)->expr = unshare_expr (simplified);
-               }
-           }
-         else if (stmt_has_constants (stmt)
-                  && TREE_CODE (lhs) == SSA_NAME)
-           VN_INFO (lhs)->has_constants = true;
-         else if (TREE_CODE (lhs) == SSA_NAME)
-           {
-             /* We reset expr and constantness here because we may
-                have been value numbering optimistically, and
-                iterating. They may become non-constant in this case,
-                even if they were optimistically constant. */
- 
-             VN_INFO (lhs)->has_constants = false;
-             VN_INFO (lhs)->expr = NULL_TREE;
-           }
  
          if ((TREE_CODE (lhs) == SSA_NAME
               /* We can substitute SSA_NAMEs that are live over
--- 3422,3427 ----
*************** visit_use (tree use)
*** 3777,3783 ****
                  || (simplified
                      && is_gimple_min_invariant (simplified)))
                {
-                 VN_INFO (lhs)->has_constants = true;
                  if (simplified)
                    changed = set_ssa_val_to (lhs, simplified);
                  else
--- 3446,3451 ----
*************** visit_use (tree use)
*** 3840,3850 ****
                      print_gimple_expr (dump_file, stmt, 0, 0);
                      fprintf (dump_file, " simplified to ");
                      print_generic_expr (dump_file, simplified, 0);
!                     if (TREE_CODE (lhs) == SSA_NAME)
!                       fprintf (dump_file, " has constants %d\n",
!                                expr_has_constants (simplified));
!                     else
!                       fprintf (dump_file, "\n");
                    }
                }
              /* Setting value numbers to constants will occasionally
--- 3508,3514 ----
                      print_gimple_expr (dump_file, stmt, 0, 0);
                      fprintf (dump_file, " simplified to ");
                      print_generic_expr (dump_file, simplified, 0);
!                     fprintf (dump_file, "\n");
                    }
                }
              /* Setting value numbers to constants will occasionally
*************** visit_use (tree use)
*** 3854,3861 ****
              if (simplified
                  && is_gimple_min_invariant (simplified))
                {
-                 VN_INFO (lhs)->expr = simplified;
-                 VN_INFO (lhs)->has_constants = true;
                  changed = set_ssa_val_to (lhs, simplified);
                  if (gimple_vdef (stmt))
                    changed |= set_ssa_val_to (gimple_vdef (stmt),
--- 3518,3523 ----
*************** visit_use (tree use)
*** 3873,3890 ****
                }
              else
                {
-                 if (stmt_has_constants (stmt))
-                   VN_INFO (lhs)->has_constants = true;
-                 else
-                   {
-                     /* We reset expr and constantness here because we may
-                        have been value numbering optimistically, and
-                        iterating.  They may become non-constant in this case,
-                        even if they were optimistically constant.  */
-                     VN_INFO (lhs)->has_constants = false;
-                     VN_INFO (lhs)->expr = NULL_TREE;
-                   }
- 
                  if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
                    {
                      changed = defs_to_varying (stmt);
--- 3535,3540 ----
*************** process_scc (vec<tree> scc)
*** 4083,4089 ****
        optimistic_info->phis_pool->release ();
        optimistic_info->references_pool->release ();
        FOR_EACH_VEC_ELT (scc, i, var)
!       VN_INFO (var)->expr = NULL_TREE;
        FOR_EACH_VEC_ELT (scc, i, var)
        changed |= visit_use (var);
      }
--- 3733,3740 ----
        optimistic_info->phis_pool->release ();
        optimistic_info->references_pool->release ();
        FOR_EACH_VEC_ELT (scc, i, var)
!       gcc_assert (!VN_INFO (var)->needs_insertion
!                   && VN_INFO (var)->expr == NULL);
        FOR_EACH_VEC_ELT (scc, i, var)
        changed |= visit_use (var);
      }
*************** init_scc_vn (void)
*** 4338,4344 ****
        continue;
  
        VN_INFO_GET (name)->valnum = VN_TOP;
!       VN_INFO (name)->expr = NULL_TREE;
        VN_INFO (name)->value_id = 0;
  
        if (!SSA_NAME_IS_DEFAULT_DEF (name))
--- 3989,3996 ----
        continue;
  
        VN_INFO_GET (name)->valnum = VN_TOP;
!       VN_INFO (name)->needs_insertion = false;
!       VN_INFO (name)->expr = NULL;
        VN_INFO (name)->value_id = 0;
  
        if (!SSA_NAME_IS_DEFAULT_DEF (name))
*************** sccvn_dom_walker::before_dom_children (b
*** 4692,4714 ****
      {
      case GIMPLE_COND:
        {
!       tree lhs = gimple_cond_lhs (stmt);
!       tree rhs = gimple_cond_rhs (stmt);
!       /* Work hard in computing the condition and take into account
!          the valueization of the defining stmt.  */
!       if (TREE_CODE (lhs) == SSA_NAME)
!         lhs = vn_get_expr_for (lhs);
!       if (TREE_CODE (rhs) == SSA_NAME)
!         rhs = vn_get_expr_for (rhs);
!       val = fold_binary (gimple_cond_code (stmt),
!                          boolean_type_node, lhs, rhs);
        /* If that didn't simplify to a constant see if we have recorded
           temporary expressions from taken edges.  */
        if (!val || TREE_CODE (val) != INTEGER_CST)
          {
            tree ops[2];
!           ops[0] = gimple_cond_lhs (stmt);
!           ops[1] = gimple_cond_rhs (stmt);
            val = vn_nary_op_lookup_pieces (2, gimple_cond_code (stmt),
                                            boolean_type_node, ops, NULL);
          }
--- 4344,4361 ----
      {
      case GIMPLE_COND:
        {
!       tree lhs = vn_valueize (gimple_cond_lhs (stmt));
!       tree rhs = vn_valueize (gimple_cond_rhs (stmt));
!       val = gimple_simplify (gimple_cond_code (stmt),
!                              boolean_type_node, lhs, rhs,
!                              NULL, vn_valueize);
        /* If that didn't simplify to a constant see if we have recorded
           temporary expressions from taken edges.  */
        if (!val || TREE_CODE (val) != INTEGER_CST)
          {
            tree ops[2];
!           ops[0] = lhs;
!           ops[1] = rhs;
            val = vn_nary_op_lookup_pieces (2, gimple_cond_code (stmt),
                                            boolean_type_node, ops, NULL);
          }
Index: gcc/gimple-match-head.c
===================================================================
*** gcc/gimple-match-head.c.orig        2015-09-30 15:00:30.636706575 +0200
--- gcc/gimple-match-head.c     2015-09-30 15:22:48.939766818 +0200
*************** maybe_build_generic_op (enum tree_code c
*** 293,298 ****
--- 293,300 ----
      }
  }
  
+ tree (*mprts_hook) (code_helper, tree, tree *);
+ 
  /* Push the exploded expression described by RCODE, TYPE and OPS
     as a statement to SEQ if necessary and return a gimple value
     denoting the value of the expression.  If RES is not NULL
*************** maybe_push_res_to_seq (code_helper rcode
*** 310,315 ****
--- 312,323 ----
              || ((tree_code) rcode) == ADDR_EXPR)
          && is_gimple_val (ops[0]))
        return ops[0];
+       if (mprts_hook)
+       {
+         tree tem = mprts_hook (rcode, type, ops);
+         if (tem)
+           return tem;
+       }
        if (!seq)
        return NULL_TREE;
        /* Play safe and do not allow abnormals to be mentioned in
Index: gcc/gimple-match.h
===================================================================
*** gcc/gimple-match.h.orig     2015-09-30 15:00:30.636706575 +0200
--- gcc/gimple-match.h  2015-09-30 15:22:48.939766818 +0200
*************** private:
*** 40,45 ****
--- 40,47 ----
    int rep;
  };
  
+ extern tree (*mprts_hook) (code_helper, tree, tree *);
+ 
  bool gimple_simplify (gimple *, code_helper *, tree *, gimple_seq *,
                      tree (*)(tree), tree (*)(tree));
  tree maybe_push_res_to_seq (code_helper, tree, tree *,
Index: gcc/tree-ssa-sccvn.h
===================================================================
*** gcc/tree-ssa-sccvn.h.orig   2015-09-30 15:00:30.636706575 +0200
--- gcc/tree-ssa-sccvn.h        2015-09-30 15:22:48.940766830 +0200
*************** typedef struct vn_ssa_aux
*** 165,172 ****
  {
    /* Value number. This may be an SSA name or a constant.  */
    tree valnum;
!   /* Representative expression, if not a direct constant. */
!   tree expr;
  
    /* Unique identifier that all expressions with the same value have. */
    unsigned int value_id;
--- 165,172 ----
  {
    /* Value number. This may be an SSA name or a constant.  */
    tree valnum;
!   /* Statements to insert if needs_insertion is true.  */
!   gimple_seq expr;
  
    /* Unique identifier that all expressions with the same value have. */
    unsigned int value_id;
*************** typedef struct vn_ssa_aux
*** 177,184 ****
    unsigned visited : 1;
    unsigned on_sccstack : 1;
  
-   /* Whether the representative expression contains constants.  */
-   unsigned has_constants : 1;
    /* Whether the SSA_NAME has been value numbered already.  This is
       only saying whether visit_use has been called on it at least
       once.  It cannot be used to avoid visitation for SSA_NAME's
--- 177,182 ----
Index: gcc/tree-ssa-pre.c
===================================================================
*** gcc/tree-ssa-pre.c.orig     2015-09-30 15:00:30.636706575 +0200
--- gcc/tree-ssa-pre.c  2015-09-30 15:22:48.941766841 +0200
*************** eliminate_push_avail (tree op)
*** 3953,3973 ****
  static tree
  eliminate_insert (gimple_stmt_iterator *gsi, tree val)
  {
!   tree expr = vn_get_expr_for (val);
!   if (!CONVERT_EXPR_P (expr)
!       && TREE_CODE (expr) != VIEW_CONVERT_EXPR)
      return NULL_TREE;
  
!   tree op = TREE_OPERAND (expr, 0);
    tree leader = TREE_CODE (op) == SSA_NAME ? eliminate_avail (op) : op;
    if (!leader)
      return NULL_TREE;
  
!   tree res = make_temp_ssa_name (TREE_TYPE (val), NULL, "pretmp");
!   gassign *tem = gimple_build_assign (res,
!                                     fold_build1 (TREE_CODE (expr),
!                                                  TREE_TYPE (expr), leader));
!   gsi_insert_before (gsi, tem, GSI_SAME_STMT);
    VN_INFO_GET (res)->valnum = val;
  
    if (TREE_CODE (leader) == SSA_NAME)
--- 3953,3975 ----
  static tree
  eliminate_insert (gimple_stmt_iterator *gsi, tree val)
  {
!   gimple *stmt = gimple_seq_first_stmt (VN_INFO (val)->expr);
!   if (!is_gimple_assign (stmt)
!       || (!CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (stmt))
!         && gimple_assign_rhs_code (stmt) != VIEW_CONVERT_EXPR))
      return NULL_TREE;
  
!   tree op = gimple_assign_rhs1 (stmt);
!   if (gimple_assign_rhs_code (stmt) == VIEW_CONVERT_EXPR)
!     op = TREE_OPERAND (op, 0);
    tree leader = TREE_CODE (op) == SSA_NAME ? eliminate_avail (op) : op;
    if (!leader)
      return NULL_TREE;
  
!   gimple_seq stmts = NULL;
!   tree res = gimple_build (&stmts, gimple_assign_rhs_code (stmt),
!                          TREE_TYPE (val), leader);
!   gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
    VN_INFO_GET (res)->valnum = val;
  
    if (TREE_CODE (leader) == SSA_NAME)
*************** eliminate_insert (gimple_stmt_iterator *
*** 3977,3983 ****
    if (dump_file && (dump_flags & TDF_DETAILS))
      {
        fprintf (dump_file, "Inserted ");
!       print_gimple_stmt (dump_file, tem, 0, 0);
      }
  
    return res;
--- 3979,3985 ----
    if (dump_file && (dump_flags & TDF_DETAILS))
      {
        fprintf (dump_file, "Inserted ");
!       print_gimple_stmt (dump_file, SSA_NAME_DEF_STMT (res), 0, 0);
      }
  
    return res;
*************** eliminate_dom_walker::before_dom_childre
*** 4101,4107 ****
              if (val != VN_TOP
                  && TREE_CODE (val) == SSA_NAME
                  && VN_INFO (val)->needs_insertion
!                 && VN_INFO (val)->expr != NULL_TREE
                  && (sprime = eliminate_insert (&gsi, val)) != NULL_TREE)
                eliminate_push_avail (sprime);
            }
--- 4103,4109 ----
              if (val != VN_TOP
                  && TREE_CODE (val) == SSA_NAME
                  && VN_INFO (val)->needs_insertion
!                 && VN_INFO (val)->expr != NULL
                  && (sprime = eliminate_insert (&gsi, val)) != NULL_TREE)
                eliminate_push_avail (sprime);
            }
Index: gcc/gimple-fold.c
===================================================================
*** gcc/gimple-fold.c.orig      2015-09-30 15:00:30.636706575 +0200
--- gcc/gimple-fold.c   2015-09-30 15:22:48.942766852 +0200
*************** gimple_fold_stmt_to_constant_1 (gimple *
*** 4883,4904 ****
       edges if there are intermediate VARYING defs.  For this reason
       do not follow SSA edges here even though SCCVN can technically
       just deal fine with that.  */
!   if (gimple_simplify (stmt, &rcode, ops, NULL, gvalueize, valueize)
!       && rcode.is_tree_code ()
!       && (TREE_CODE_LENGTH ((tree_code) rcode) == 0
!         || ((tree_code) rcode) == ADDR_EXPR)
!       && is_gimple_val (ops[0]))
      {
!       tree res = ops[0];
!       if (dump_file && dump_flags & TDF_DETAILS)
        {
!         fprintf (dump_file, "Match-and-simplified ");
!         print_gimple_expr (dump_file, stmt, 0, TDF_SLIM);
!         fprintf (dump_file, " to ");
!         print_generic_expr (dump_file, res, 0);
!         fprintf (dump_file, "\n");
        }
-       return res;
      }
  
    location_t loc = gimple_location (stmt);
--- 4883,4910 ----
       edges if there are intermediate VARYING defs.  For this reason
       do not follow SSA edges here even though SCCVN can technically
       just deal fine with that.  */
!   if (gimple_simplify (stmt, &rcode, ops, NULL, gvalueize, valueize))
      {
!       tree res = NULL_TREE;
!       if (rcode.is_tree_code ()
!         && (TREE_CODE_LENGTH ((tree_code) rcode) == 0
!             || ((tree_code) rcode) == ADDR_EXPR)
!         && is_gimple_val (ops[0]))
!       res = ops[0];
!       else if (mprts_hook)
!       res = mprts_hook (rcode, gimple_expr_type (stmt), ops);
!       if (res)
        {
!         if (dump_file && dump_flags & TDF_DETAILS)
!           {
!             fprintf (dump_file, "Match-and-simplified ");
!             print_gimple_expr (dump_file, stmt, 0, TDF_SLIM);
!             fprintf (dump_file, " to ");
!             print_generic_expr (dump_file, res, 0);
!             fprintf (dump_file, "\n");
!           }
!         return res;
        }
      }
  
    location_t loc = gimple_location (stmt);
Index: gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-7.c
===================================================================
*** gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-7.c.orig      2015-09-30 
15:35:37.715366242 +0200
--- gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-7.c   2015-09-30 15:35:48.739489118 
+0200
*************** intflt foo(intflt j)
*** 29,36 ****
    return a.u.k;
  }
  
! /* { dg-final { scan-tree-dump-times "Inserted pretmp" 1 "fre1" } } */
! /* { dg-final { scan-tree-dump-times "Replaced a.u.f with pretmp" 3 "fre1" } 
} */
  /* { dg-final { scan-tree-dump-times "Replaced a.u.k with j" 1 "fre1" } } */
  /* { dg-final { scan-tree-dump "= VIEW_CONVERT_EXPR<float>\\\(j_" "fre1" } } 
*/
  /* { dg-final { scan-tree-dump "return j" "optimized" } } */
--- 29,36 ----
    return a.u.k;
  }
  
! /* { dg-final { scan-tree-dump-times "Inserted" 1 "fre1" } } */
! /* { dg-final { scan-tree-dump-times "Replaced a.u.f with" 3 "fre1" } } */
  /* { dg-final { scan-tree-dump-times "Replaced a.u.k with j" 1 "fre1" } } */
  /* { dg-final { scan-tree-dump "= VIEW_CONVERT_EXPR<float>\\\(j_" "fre1" } } 
*/
  /* { dg-final { scan-tree-dump "return j" "optimized" } } */
Index: gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-8.c
===================================================================
*** gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-8.c.orig      2015-09-30 
15:35:37.724366342 +0200
--- gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-8.c   2015-09-30 15:35:48.740489129 
+0200
*************** intflt foo(int i, int b)
*** 28,32 ****
      }
  }
  
! /* { dg-final { scan-tree-dump-times "Replaced u.f with pretmp" 2 "fre1" } } 
*/
! /* { dg-final { scan-tree-dump-times "Inserted pretmp" 2 "fre1" } } */
--- 28,32 ----
      }
  }
  
! /* { dg-final { scan-tree-dump-times "Replaced u.f with" 2 "fre1" } } */
! /* { dg-final { scan-tree-dump-times "Inserted" 2 "fre1" } } */

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