gcc/value-range-storage.h

   1 /* Support routines for vrange storage.
   2    Copyright (C) 2022 Free Software Foundation, Inc.
   3    Contributed by Aldy Hernandez <aldyh@redhat.com>.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 3, or (at your option)
  10 any later version.
  11
  12 GCC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 #ifndef GCC_VALUE_RANGE_STORAGE_H
  22 #define GCC_VALUE_RANGE_STORAGE_H
  23
  24 // This class is used to allocate the minimum amount of storage needed
  25 // for a given range.  Storage is automatically freed at destruction
  26 // of the class.
  27
  28 class vrange_allocator
  29 {
  30 public:
  31   vrange_allocator () { }
  32   virtual ~vrange_allocator () { }
  33   // Allocate a range of TYPE.
  34   vrange *alloc_vrange (tree type);
  35   // Allocate a memory block of BYTES.
  36   virtual void *alloc (unsigned bytes) = 0;
  37   virtual void free (void *p) = 0;
  38   // Return a clone of SRC.
  39   template <typename T> T *clone (const T &src);
  40 private:
  41   irange *alloc_irange (unsigned pairs);
  42   frange *alloc_frange ();
  43   void operator= (const vrange_allocator &) = delete;
  44 };
  45
  46 // This class is used to allocate chunks of memory that can store
  47 // ranges as memory efficiently as possible.  It is meant to be used
  48 // when long term storage of a range is needed.  The class can be used
  49 // with any vrange_allocator (i.e. alloca or GC).
  50
  51 class vrange_storage
  52 {
  53 public:
  54   vrange_storage (vrange_allocator *alloc) : m_alloc (alloc) { }
  55   void *alloc_slot (const vrange &r);
  56   void free (void *slot) { m_alloc->free (slot); }
  57   void get_vrange (const void *slot, vrange &r, tree type);
  58   void set_vrange (void *slot, const vrange &r);
  59   static bool fits_p (const void *slot, const vrange &r);
  60 private:
  61   DISABLE_COPY_AND_ASSIGN (vrange_storage);
  62   vrange_allocator *m_alloc;
  63 };
  64
  65 // A chunk of memory pointing to an irange storage.
  66
  67 class GTY ((variable_size)) irange_storage_slot
  68 {
  69 public:
  70   static irange_storage_slot *alloc_slot (vrange_allocator &, const irange &r);
  71   void set_irange (const irange &r);
  72   void get_irange (irange &r, tree type) const;
  73   wide_int get_nonzero_bits () const { return m_ints[0]; }
  74   bool fits_p (const irange &r) const;
  75   static size_t size (const irange &r);
  76   void dump () const;
  77 private:
  78   DISABLE_COPY_AND_ASSIGN (irange_storage_slot);
  79   friend void gt_ggc_mx_irange_storage_slot (void *);
  80   friend void gt_pch_p_19irange_storage_slot (void *, void *,
  81                                               gt_pointer_operator, void *);
  82   friend void gt_pch_nx_irange_storage_slot (void *);
  83
  84   // This is the maximum number of wide_int's allowed in the trailing
  85   // ints structure, without going over 16 bytes (128 bits) in the
  86   // control word that preceeds the HOST_WIDE_INTs in
  87   // trailing_wide_ints::m_val[].
  88   static const unsigned MAX_INTS = 12;
  89
  90   // Maximum number of range pairs we can handle, considering the
  91   // nonzero bits take one wide_int.
  92   static const unsigned MAX_PAIRS = (MAX_INTS - 1) / 2;
  93
  94   // Constructor is private to disallow stack initialization.  Use
  95   // alloc_slot() to create objects.
  96   irange_storage_slot (const irange &r);
  97
  98   static unsigned num_wide_ints_needed (const irange &r);
  99
 100   trailing_wide_ints<MAX_INTS> m_ints;
 101 };
 102
 103 // A chunk of memory to store an frange to long term memory.
 104
 105 class GTY (()) frange_storage_slot
 106 {
 107  public:
 108   static frange_storage_slot *alloc_slot (vrange_allocator &, const frange &r);
 109   void set_frange (const frange &r);
 110   void get_frange (frange &r, tree type) const;
 111   bool fits_p (const frange &) const;
 112  private:
 113   frange_storage_slot (const frange &r) { set_frange (r); }
 114   DISABLE_COPY_AND_ASSIGN (frange_storage_slot);
 115
 116   enum value_range_kind m_kind;
 117   REAL_VALUE_TYPE m_min;
 118   REAL_VALUE_TYPE m_max;
 119   bool m_pos_nan;
 120   bool m_neg_nan;
 121 };
 122
 123 class obstack_vrange_allocator final: public vrange_allocator
 124 {
 125 public:
 126   obstack_vrange_allocator ()
 127   {
 128     obstack_init (&m_obstack);
 129   }
 130   virtual ~obstack_vrange_allocator () final override
 131   {
 132     obstack_free (&m_obstack, NULL);
 133   }
 134   virtual void *alloc (unsigned bytes) final override
 135   {
 136     return obstack_alloc (&m_obstack, bytes);
 137   }
 138   virtual void free (void *) final override { }
 139 private:
 140   obstack m_obstack;
 141 };
 142
 143 class ggc_vrange_allocator final: public vrange_allocator
 144 {
 145 public:
 146   ggc_vrange_allocator () { }
 147   virtual ~ggc_vrange_allocator () final override { }
 148   virtual void *alloc (unsigned bytes) final override
 149   {
 150     return ggc_internal_alloc (bytes);
 151   }
 152   virtual void free (void *p) final override
 153   {
 154     return ggc_free (p);
 155   }
 156 };
 157
 158 // Return a new range to hold ranges of TYPE.  The newly allocated
 159 // range is initialized to VR_UNDEFINED.
 160
 161 inline vrange *
 162 vrange_allocator::alloc_vrange (tree type)
 163 {
 164   if (irange::supports_p (type))
 165     return alloc_irange (2);
 166   if (frange::supports_p (type))
 167     return alloc_frange ();
 168   return NULL;
 169   gcc_unreachable ();
 170 }
 171
 172 // Return a new range with NUM_PAIRS.
 173
 174 inline irange *
 175 vrange_allocator::alloc_irange (unsigned num_pairs)
 176 {
 177   // Never allocate 0 pairs.
 178   // Don't allocate 1 either, or we get legacy value_range's.
 179   if (num_pairs < 2)
 180     num_pairs = 2;
 181
 182   size_t nbytes = sizeof (tree) * 2 * num_pairs;
 183
 184   // Allocate the irange and required memory for the vector.
 185   void *r = alloc (sizeof (irange));
 186   tree *mem = static_cast <tree *> (alloc (nbytes));
 187   return new (r) irange (mem, num_pairs);
 188 }
 189
 190 inline frange *
 191 vrange_allocator::alloc_frange ()
 192 {
 193   void *r = alloc (sizeof (frange));
 194   return new (r) frange ();
 195 }
 196
 197 // Return a clone of an irange.
 198
 199 template <>
 200 inline irange *
 201 vrange_allocator::clone <irange> (const irange &src)
 202 {
 203   irange *r = alloc_irange (src.num_pairs ());
 204   *r = src;
 205   return r;
 206 }
 207
 208 // Return a clone of an frange.
 209
 210 template <>
 211 inline frange *
 212 vrange_allocator::clone <frange> (const frange &src)
 213 {
 214   frange *r = alloc_frange ();
 215   *r = src;
 216   return r;
 217 }
 218
 219 // Return a clone of a vrange.
 220
 221 template <>
 222 inline vrange *
 223 vrange_allocator::clone <vrange> (const vrange &src)
 224 {
 225   if (is_a <irange> (src))
 226     return clone <irange> (as_a <irange> (src));
 227   if (is_a <frange> (src))
 228     return clone <frange> (as_a <frange> (src));
 229   return NULL;
 230   gcc_unreachable ();
 231 }
 232
 233 #endif // GCC_VALUE_RANGE_STORAGE_H