gcc/tree-ssa-loop.h

   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.  This information is used by
  58      loop unrolling.  If CMP is ERROR_MARK, then the loop cannot be unrolled.
  59      Otherwise, the loop exits if CONTROL CMP BOUND is false, where CMP is one
  60      of NE_EXPR, LT_EXPR, or GT_EXPR, and CONTROL.STEP is positive if CMP is
  61      LT_EXPR and negative if CMP is GT_EXPR.  */
  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 */