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      1 /* Header file for SSA loop optimizations.
      2    Copyright (C) 2013-2022 Free Software Foundation, Inc.
      3 
      4 This file is part of GCC.
      5 
      6 GCC is free software; you can redistribute it and/or modify it under
      7 the terms of the GNU General Public License as published by the Free
      8 Software Foundation; either version 3, or (at your option) any later
      9 version.
     10 
     11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
     12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
     13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
     14  for more details.
     15 
     16 You should have received a copy of the GNU General Public License
     17 along with GCC; see the file COPYING3.  If not see
     18 <http://www.gnu.org/licenses/>.  */
     19 
     20 #ifndef GCC_TREE_SSA_LOOP_H
     21 #define GCC_TREE_SSA_LOOP_H
     22 
     23 
     24 /* Affine iv.  */
     25 
     26 struct affine_iv
     27 {
     28   /* Iv = BASE + STEP * i.  */
     29   tree base, step;
     30 
     31   /* True if this iv does not overflow.  */
     32   bool no_overflow;
     33 };
     34 
     35 /* Description of number of iterations of a loop.  All the expressions inside
     36    the structure can be evaluated at the end of the loop's preheader
     37    (and due to ssa form, also anywhere inside the body of the loop).  */
     38 
     39 class tree_niter_desc
     40 {
     41 public:
     42   tree assumptions;	/* The boolean expression.  If this expression evaluates
     43 			   to false, then the other fields in this structure
     44 			   should not be used; there is no guarantee that they
     45 			   will be correct.  */
     46   tree may_be_zero;	/* The boolean expression.  If it evaluates to true,
     47 			   the loop will exit in the first iteration (i.e.
     48 			   its latch will not be executed), even if the niter
     49 			   field says otherwise.  */
     50   tree niter;		/* The expression giving the number of iterations of
     51 			   a loop (provided that assumptions == true and
     52 			   may_be_zero == false), more precisely the number
     53 			   of executions of the latch of the loop.  */
     54   widest_int max;	/* The upper bound on the number of iterations of
     55 			   the loop.  */
     56 
     57   /* The simplified shape of the exit condition.  The loop exits if
     58      CONTROL CMP BOUND is false, where CMP is one of NE_EXPR,
     59      LT_EXPR, or GT_EXPR, and step of CONTROL is positive if CMP is
     60      LE_EXPR and negative if CMP is GE_EXPR.  This information is used
     61      by loop unrolling.  */
     62   affine_iv control;
     63   tree bound;
     64   enum tree_code cmp;
     65 };
     66 
     67 extern bool for_each_index (tree *, bool (*) (tree, tree *, void *), void *);
     68 extern char *get_lsm_tmp_name (tree ref, unsigned n, const char *suffix = NULL);
     69 extern unsigned tree_num_loop_insns (class loop *, struct eni_weights *);
     70 
     71 /* Returns the loop of the statement STMT.  */
     72 
     73 static inline class loop *
     74 loop_containing_stmt (gimple *stmt)
     75 {
     76   basic_block bb = gimple_bb (stmt);
     77   if (!bb)
     78     return NULL;
     79 
     80   return bb->loop_father;
     81 }
     82 
     83 #endif /* GCC_TREE_SSA_LOOP_H */
     84