gcc/value-range-storage.cc

   1 /* Support routines for vrange storage.
   2    Copyright (C) 2022-2023 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 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "backend.h"
  25 #include "tree.h"
  26 #include "gimple.h"
  27 #include "ssa.h"
  28 #include "tree-pretty-print.h"
  29 #include "fold-const.h"
  30 #include "gimple-range.h"
  31 #include "value-range-storage.h"
  32
  33 // Return a newly allocated slot holding R, or NULL if storing a range
  34 // of R's type is not supported.
  35
  36 void *
  37 vrange_storage::alloc_slot (const vrange &r)
  38 {
  39   gcc_checking_assert (m_alloc);
  40
  41   if (is_a <irange> (r))
  42     return irange_storage_slot::alloc_slot (*m_alloc, as_a <irange> (r));
  43   if (is_a <frange> (r))
  44     return frange_storage_slot::alloc_slot (*m_alloc, as_a <frange> (r));
  45   return NULL;
  46 }
  47
  48 // Set SLOT to R.
  49
  50 void
  51 vrange_storage::set_vrange (void *slot, const vrange &r)
  52 {
  53   if (is_a <irange> (r))
  54     {
  55       irange_storage_slot *s = static_cast <irange_storage_slot *> (slot);
  56       gcc_checking_assert (s->fits_p (as_a <irange> (r)));
  57       s->set_irange (as_a <irange> (r));
  58     }
  59   else if (is_a <frange> (r))
  60     {
  61       frange_storage_slot *s = static_cast <frange_storage_slot *> (slot);
  62       gcc_checking_assert (s->fits_p (as_a <frange> (r)));
  63       s->set_frange (as_a <frange> (r));
  64     }
  65   else
  66     gcc_unreachable ();
  67 }
  68
  69 // Restore R from SLOT.  TYPE is the type of R.
  70
  71 void
  72 vrange_storage::get_vrange (const void *slot, vrange &r, tree type)
  73 {
  74   if (is_a <irange> (r))
  75     {
  76       const irange_storage_slot *s
  77         = static_cast <const irange_storage_slot *> (slot);
  78       s->get_irange (as_a <irange> (r), type);
  79     }
  80   else if (is_a <frange> (r))
  81     {
  82       const frange_storage_slot *s
  83         = static_cast <const frange_storage_slot *> (slot);
  84       s->get_frange (as_a <frange> (r), type);
  85     }
  86   else
  87     gcc_unreachable ();
  88 }
  89
  90 // Return TRUE if SLOT can fit R.
  91
  92 bool
  93 vrange_storage::fits_p (const void *slot, const vrange &r)
  94 {
  95   if (is_a <irange> (r))
  96     {
  97       const irange_storage_slot *s
  98         = static_cast <const irange_storage_slot *> (slot);
  99       return s->fits_p (as_a <irange> (r));
 100     }
 101   if (is_a <frange> (r))
 102     {
 103       const frange_storage_slot *s
 104         = static_cast <const frange_storage_slot *> (slot);
 105       return s->fits_p (as_a <frange> (r));
 106     }
 107   gcc_unreachable ();
 108   return false;
 109 }
 110
 111 // Factory that creates a new irange_storage_slot object containing R.
 112 // This is the only way to construct an irange slot as stack creation
 113 // is disallowed.
 114
 115 irange_storage_slot *
 116 irange_storage_slot::alloc_slot (vrange_allocator &allocator, const irange &r)
 117 {
 118   size_t size = irange_storage_slot::size (r);
 119   irange_storage_slot *p
 120     = static_cast <irange_storage_slot *> (allocator.alloc (size));
 121   new (p) irange_storage_slot (r);
 122   return p;
 123 }
 124
 125 // Initialize the current slot with R.
 126
 127 irange_storage_slot::irange_storage_slot (const irange &r)
 128 {
 129   gcc_checking_assert (!r.undefined_p ());
 130
 131   unsigned prec = TYPE_PRECISION (r.type ());
 132   unsigned n = num_wide_ints_needed (r);
 133   if (n > MAX_INTS)
 134     {
 135       int_range<MAX_PAIRS> squash (r);
 136       m_ints.set_precision (prec, num_wide_ints_needed (squash));
 137       set_irange (squash);
 138     }
 139   else
 140     {
 141       m_ints.set_precision (prec, n);
 142       set_irange (r);
 143     }
 144 }
 145
 146 // Store R into the current slot.
 147
 148 void
 149 irange_storage_slot::set_irange (const irange &r)
 150 {
 151   gcc_checking_assert (fits_p (r));
 152
 153   m_ints[0] = r.get_nonzero_bits ();
 154
 155   unsigned pairs = r.num_pairs ();
 156   for (unsigned i = 0; i < pairs; ++i)
 157     {
 158       m_ints[i*2 + 1] = r.lower_bound (i);
 159       m_ints[i*2 + 2] = r.upper_bound (i);
 160     }
 161 }
 162
 163 // Restore a range of TYPE from the current slot into R.
 164
 165 void
 166 irange_storage_slot::get_irange (irange &r, tree type) const
 167 {
 168   gcc_checking_assert (TYPE_PRECISION (type) == m_ints.get_precision ());
 169
 170   r.set_undefined ();
 171   unsigned nelements = m_ints.num_elements ();
 172   for (unsigned i = 1; i < nelements; i += 2)
 173     {
 174       int_range<2> tmp (type, m_ints[i], m_ints[i + 1]);
 175       r.union_ (tmp);
 176     }
 177   r.set_nonzero_bits (get_nonzero_bits ());
 178 }
 179
 180 // Return the size in bytes to allocate a slot that can hold R.
 181
 182 size_t
 183 irange_storage_slot::size (const irange &r)
 184 {
 185   gcc_checking_assert (!r.undefined_p ());
 186
 187   unsigned prec = TYPE_PRECISION (r.type ());
 188   unsigned n = num_wide_ints_needed (r);
 189   if (n > MAX_INTS)
 190     n = MAX_INTS;
 191   return (sizeof (irange_storage_slot)
 192           + trailing_wide_ints<MAX_INTS>::extra_size (prec, n));
 193 }
 194
 195 // Return the number of wide ints needed to represent R.
 196
 197 unsigned int
 198 irange_storage_slot::num_wide_ints_needed (const irange &r)
 199 {
 200   return r.num_pairs () * 2 + 1;
 201 }
 202
 203 // Return TRUE if R fits in the current slot.
 204
 205 bool
 206 irange_storage_slot::fits_p (const irange &r) const
 207 {
 208   return m_ints.num_elements () >= num_wide_ints_needed (r);
 209 }
 210
 211 // Dump the current slot.
 212
 213 void
 214 irange_storage_slot::dump () const
 215 {
 216   fprintf (stderr, "raw irange_storage_slot:\n");
 217   for (unsigned i = 1; i < m_ints.num_elements (); i += 2)
 218     {
 219       m_ints[i].dump ();
 220       m_ints[i + 1].dump ();
 221     }
 222   fprintf (stderr, "NONZERO ");
 223   wide_int nz = get_nonzero_bits ();
 224   nz.dump ();
 225 }
 226
 227 DEBUG_FUNCTION void
 228 debug (const irange_storage_slot &storage)
 229 {
 230   storage.dump ();
 231   fprintf (stderr, "\n");
 232 }
 233
 234 // Implementation of frange_storage_slot.
 235
 236 frange_storage_slot *
 237 frange_storage_slot::alloc_slot (vrange_allocator &allocator, const frange &r)
 238 {
 239   size_t size = sizeof (frange_storage_slot);
 240   frange_storage_slot *p
 241     = static_cast <frange_storage_slot *> (allocator.alloc (size));
 242   new (p) frange_storage_slot (r);
 243   return p;
 244 }
 245
 246 void
 247 frange_storage_slot::set_frange (const frange &r)
 248 {
 249   gcc_checking_assert (fits_p (r));
 250   gcc_checking_assert (!r.undefined_p ());
 251
 252   m_kind = r.m_kind;
 253   m_min = r.m_min;
 254   m_max = r.m_max;
 255   m_pos_nan = r.m_pos_nan;
 256   m_neg_nan = r.m_neg_nan;
 257 }
 258
 259 void
 260 frange_storage_slot::get_frange (frange &r, tree type) const
 261 {
 262   gcc_checking_assert (r.supports_type_p (type));
 263
 264   // Handle explicit NANs.
 265   if (m_kind == VR_NAN)
 266     {
 267       if (HONOR_NANS (type))
 268         {
 269           if (m_pos_nan && m_neg_nan)
 270             r.set_nan (type);
 271           else
 272             r.set_nan (type, m_neg_nan);
 273         }
 274       else
 275         r.set_undefined ();
 276       return;
 277     }
 278
 279   // We use the constructor to create the new range instead of writing
 280   // out the bits into the frange directly, because the global range
 281   // being read may be being inlined into a function with different
 282   // restrictions as when it was originally written.  We want to make
 283   // sure the resulting range is canonicalized correctly for the new
 284   // consumer.
 285   r = frange (type, m_min, m_max, m_kind);
 286
 287   // The constructor will set the NAN bits for HONOR_NANS, but we must
 288   // make sure to set the NAN sign if known.
 289   if (HONOR_NANS (type) && (m_pos_nan ^ m_neg_nan) == 1)
 290     r.update_nan (m_neg_nan);
 291   else if (!m_pos_nan && !m_neg_nan)
 292     r.clear_nan ();
 293 }
 294
 295 bool
 296 frange_storage_slot::fits_p (const frange &) const
 297 {
 298   return true;
 299 }