gcc/value-range.h

   1 /* Support routines for value ranges.
   2    Copyright (C) 2019-2021 Free Software Foundation, Inc.
   3    Contributed by Aldy Hernandez <aldyh@redhat.com> and
   4    Andrew Macleod <amacleod@redhat.com>.
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 3, or (at your option)
  11 any later version.
  12
  13 GCC is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 #ifndef GCC_VALUE_RANGE_H
  23 #define GCC_VALUE_RANGE_H
  24
  25 // Types of value ranges.
  26 enum value_range_kind
  27 {
  28   /* Empty range.  */
  29   VR_UNDEFINED,
  30   /* Range spans the entire domain.  */
  31   VR_VARYING,
  32   /* Range is [MIN, MAX].  */
  33   VR_RANGE,
  34   /* Range is ~[MIN, MAX].  */
  35   VR_ANTI_RANGE,
  36   /* Range is a nice guy.  */
  37   VR_LAST
  38 };
  39
  40 // Range of values that can be associated with an SSA_NAME.
  41 //
  42 // This is the base class without any storage.
  43
  44 class GTY((user)) irange
  45 {
  46   friend class irange_allocator;
  47 public:
  48   // In-place setters.
  49   void set (tree, tree, value_range_kind = VR_RANGE);
  50   void set_nonzero (tree);
  51   void set_zero (tree);
  52   void set_varying (tree type);
  53   void set_undefined ();
  54
  55   // Range types.
  56   static bool supports_type_p (tree);
  57   tree type () const;
  58
  59   // Iteration over sub-ranges.
  60   unsigned num_pairs () const;
  61   wide_int lower_bound (unsigned = 0) const;
  62   wide_int upper_bound (unsigned) const;
  63   wide_int upper_bound () const;
  64
  65   // Predicates.
  66   bool zero_p () const;
  67   bool nonzero_p () const;
  68   bool undefined_p () const;
  69   bool varying_p () const;
  70   bool singleton_p (tree *result = NULL) const;
  71   bool contains_p (tree) const;
  72
  73   // In-place operators.
  74   void union_ (const irange &);
  75   void intersect (const irange &);
  76   void intersect (const wide_int& lb, const wide_int& ub);
  77   void invert ();
  78
  79   // Operator overloads.
  80   irange& operator= (const irange &);
  81   bool operator== (const irange &) const;
  82   bool operator!= (const irange &r) const { return !(*this == r); }
  83
  84   // Misc methods.
  85   bool fits_p (const irange &r) { return m_max_ranges >= r.num_pairs (); }
  86   void dump (FILE * = stderr) const;
  87   void debug () const;
  88
  89   // Deprecated legacy public methods.
  90   enum value_range_kind kind () const;          // DEPRECATED
  91   tree min () const;                            // DEPRECATED
  92   tree max () const;                            // DEPRECATED
  93   bool symbolic_p () const;                     // DEPRECATED
  94   bool constant_p () const;                     // DEPRECATED
  95   void normalize_symbolics ();                  // DEPRECATED
  96   void normalize_addresses ();                  // DEPRECATED
  97   bool may_contain_p (tree) const;              // DEPRECATED
  98   void set (tree);                              // DEPRECATED
  99   bool equal_p (const irange &) const;          // DEPRECATED
 100   void union_ (const class irange *);           // DEPRECATED
 101   void intersect (const irange *);              // DEPRECATED
 102
 103 protected:
 104   irange (tree *, unsigned);
 105   // potential promotion to public?
 106   tree tree_lower_bound (unsigned = 0) const;
 107   tree tree_upper_bound (unsigned) const;
 108   tree tree_upper_bound () const;
 109
 110    // In-place operators.
 111   void irange_union (const irange &);
 112   void irange_intersect (const irange &);
 113   void irange_set (tree, tree);
 114   void irange_set_anti_range (tree, tree);
 115
 116   void normalize_kind ();
 117
 118   bool legacy_mode_p () const;
 119   bool legacy_equal_p (const irange &) const;
 120   void legacy_union (irange *, const irange *);
 121   void legacy_intersect (irange *, const irange *);
 122   void verify_range ();
 123   wide_int legacy_lower_bound (unsigned = 0) const;
 124   wide_int legacy_upper_bound (unsigned) const;
 125   int value_inside_range (tree) const;
 126   bool maybe_anti_range () const;
 127   void copy_to_legacy (const irange &);
 128   void copy_legacy_to_multi_range (const irange &);
 129
 130 private:
 131   friend void gt_ggc_mx (irange *);
 132   friend void gt_pch_nx (irange *);
 133   friend void gt_pch_nx (irange *, gt_pointer_operator, void *);
 134
 135   void irange_set_1bit_anti_range (tree, tree);
 136   bool varying_compatible_p () const;
 137
 138   unsigned char m_num_ranges;
 139   unsigned char m_max_ranges;
 140   ENUM_BITFIELD(value_range_kind) m_kind : 8;
 141   tree *m_base;
 142 };
 143
 144 // Here we describe an irange with N pairs of ranges.  The storage for
 145 // the pairs is embedded in the class as an array.
 146
 147 template<unsigned N>
 148 class GTY((user)) int_range : public irange
 149 {
 150 public:
 151   int_range ();
 152   int_range (tree, tree, value_range_kind = VR_RANGE);
 153   int_range (tree type, const wide_int &, const wide_int &,
 154              value_range_kind = VR_RANGE);
 155   int_range (tree type);
 156   int_range (const int_range &);
 157   int_range (const irange &);
 158   int_range& operator= (const int_range &);
 159 private:
 160   template <unsigned X> friend void gt_ggc_mx (int_range<X> *);
 161   template <unsigned X> friend void gt_pch_nx (int_range<X> *);
 162   template <unsigned X> friend void gt_pch_nx (int_range<X> *,
 163                                                gt_pointer_operator, void *);
 164
 165   // ?? These stubs are for ipa-prop.c which use a value_range in a
 166   // hash_traits.  hash-traits.h defines an extern of gt_ggc_mx (T &)
 167   // instead of picking up the gt_ggc_mx (T *) version.
 168   friend void gt_ggc_mx (int_range<1> *&);
 169   friend void gt_pch_nx (int_range<1> *&);
 170
 171   tree m_ranges[N*2];
 172 };
 173
 174 // This is a special int_range<1> with only one pair, plus
 175 // VR_ANTI_RANGE magic to describe slightly more than can be described
 176 // in one pair.  It is described in the code as a "legacy range" (as
 177 // opposed to multi-ranges which have multiple sub-ranges).  It is
 178 // provided for backward compatibility with code that has not been
 179 // converted to multi-range irange's.
 180 //
 181 // There are copy operators to seamlessly copy to/fro multi-ranges.
 182 typedef int_range<1> value_range;
 183
 184 // This is an "infinite" precision irange for use in temporary
 185 // calculations.
 186 typedef int_range<255> int_range_max;
 187
 188 // Returns true for an old-school value_range as described above.
 189 inline bool
 190 irange::legacy_mode_p () const
 191 {
 192   return m_max_ranges == 1;
 193 }
 194
 195 extern bool range_has_numeric_bounds_p (const irange *);
 196 extern bool ranges_from_anti_range (const value_range *,
 197                                     value_range *, value_range *);
 198 extern void dump_value_range (FILE *, const irange *);
 199 extern bool vrp_val_is_min (const_tree);
 200 extern bool vrp_val_is_max (const_tree);
 201 extern bool vrp_operand_equal_p (const_tree, const_tree);
 202
 203 inline value_range_kind
 204 irange::kind () const
 205 {
 206   return m_kind;
 207 }
 208
 209 // Number of sub-ranges in a range.
 210
 211 inline unsigned
 212 irange::num_pairs () const
 213 {
 214   if (m_kind == VR_ANTI_RANGE)
 215     return constant_p () ? 2 : 1;
 216   else
 217     return m_num_ranges;
 218 }
 219
 220 inline tree
 221 irange::type () const
 222 {
 223   gcc_checking_assert (m_num_ranges > 0);
 224   return TREE_TYPE (m_base[0]);
 225 }
 226
 227 // Return the lower bound of a sub-range expressed as a tree.  PAIR is
 228 // the sub-range in question.
 229
 230 inline tree
 231 irange::tree_lower_bound (unsigned pair) const
 232 {
 233   return m_base[pair * 2];
 234 }
 235
 236 // Return the upper bound of a sub-range expressed as a tree.  PAIR is
 237 // the sub-range in question.
 238
 239 inline tree
 240 irange::tree_upper_bound (unsigned pair) const
 241 {
 242   return m_base[pair * 2 + 1];
 243 }
 244
 245 // Return the highest bound of a range expressed as a tree.
 246
 247 inline tree
 248 irange::tree_upper_bound () const
 249 {
 250   gcc_checking_assert (m_num_ranges);
 251   return tree_upper_bound (m_num_ranges - 1);
 252 }
 253
 254 inline tree
 255 irange::min () const
 256 {
 257   return tree_lower_bound (0);
 258 }
 259
 260 inline tree
 261 irange::max () const
 262 {
 263   if (m_num_ranges)
 264     return tree_upper_bound ();
 265   else
 266     return NULL;
 267 }
 268
 269 inline bool
 270 irange::varying_compatible_p () const
 271 {
 272   if (m_num_ranges != 1)
 273     return false;
 274
 275   tree l = m_base[0];
 276   tree u = m_base[1];
 277   tree t = TREE_TYPE (l);
 278
 279   if (m_kind == VR_VARYING && t == error_mark_node)
 280     return true;
 281
 282   unsigned prec = TYPE_PRECISION (t);
 283   signop sign = TYPE_SIGN (t);
 284   if (INTEGRAL_TYPE_P (t))
 285     return (wi::to_wide (l) == wi::min_value (prec, sign)
 286             && wi::to_wide (u) == wi::max_value (prec, sign));
 287   if (POINTER_TYPE_P (t))
 288     return (wi::to_wide (l) == 0
 289             && wi::to_wide (u) == wi::max_value (prec, sign));
 290   return true;
 291 }
 292
 293 inline bool
 294 irange::varying_p () const
 295 {
 296   return m_kind == VR_VARYING;
 297 }
 298
 299 inline bool
 300 irange::undefined_p () const
 301 {
 302   return m_kind == VR_UNDEFINED;
 303 }
 304
 305 inline bool
 306 irange::zero_p () const
 307 {
 308   return (m_kind == VR_RANGE && m_num_ranges == 1
 309           && integer_zerop (tree_lower_bound (0))
 310           && integer_zerop (tree_upper_bound (0)));
 311 }
 312
 313 inline bool
 314 irange::nonzero_p () const
 315 {
 316   if (undefined_p ())
 317     return false;
 318
 319   tree zero = build_zero_cst (type ());
 320   return *this == int_range<1> (zero, zero, VR_ANTI_RANGE);
 321 }
 322
 323 inline bool
 324 irange::supports_type_p (tree type)
 325 {
 326   if (type && (INTEGRAL_TYPE_P (type) || POINTER_TYPE_P (type)))
 327     return type;
 328   return false;
 329 }
 330
 331 inline bool
 332 range_includes_zero_p (const irange *vr)
 333 {
 334   if (vr->undefined_p ())
 335     return false;
 336
 337   if (vr->varying_p ())
 338     return true;
 339
 340   return vr->may_contain_p (build_zero_cst (vr->type ()));
 341 }
 342
 343 inline void
 344 gt_ggc_mx (irange *x)
 345 {
 346   for (unsigned i = 0; i < x->m_num_ranges; ++i)
 347     {
 348       gt_ggc_mx (x->m_base[i * 2]);
 349       gt_ggc_mx (x->m_base[i * 2 + 1]);
 350     }
 351 }
 352
 353 inline void
 354 gt_pch_nx (irange *x)
 355 {
 356   for (unsigned i = 0; i < x->m_num_ranges; ++i)
 357     {
 358       gt_pch_nx (x->m_base[i * 2]);
 359       gt_pch_nx (x->m_base[i * 2 + 1]);
 360     }
 361 }
 362
 363 inline void
 364 gt_pch_nx (irange *x, gt_pointer_operator op, void *cookie)
 365 {
 366   for (unsigned i = 0; i < x->m_num_ranges; ++i)
 367     {
 368       op (&x->m_base[i * 2], cookie);
 369       op (&x->m_base[i * 2 + 1], cookie);
 370     }
 371 }
 372
 373 template<unsigned N>
 374 inline void
 375 gt_ggc_mx (int_range<N> *x)
 376 {
 377   gt_ggc_mx ((irange *) x);
 378 }
 379
 380 template<unsigned N>
 381 inline void
 382 gt_pch_nx (int_range<N> *x)
 383 {
 384   gt_pch_nx ((irange *) x);
 385 }
 386
 387 template<unsigned N>
 388 inline void
 389 gt_pch_nx (int_range<N> *x, gt_pointer_operator op, void *cookie)
 390 {
 391   gt_pch_nx ((irange *) x, op, cookie);
 392 }
 393
 394 // Constructors for irange
 395
 396 inline
 397 irange::irange (tree *base, unsigned nranges)
 398 {
 399   m_base = base;
 400   m_num_ranges = 0;
 401   m_max_ranges = nranges;
 402   m_kind = VR_UNDEFINED;
 403 }
 404
 405 // Constructors for int_range<>.
 406
 407 template<unsigned N>
 408 inline
 409 int_range<N>::int_range ()
 410   : irange (m_ranges, N)
 411 {
 412 }
 413
 414 template<unsigned N>
 415 int_range<N>::int_range (const int_range &other)
 416   : irange (m_ranges, N)
 417 {
 418   irange::operator= (other);
 419 }
 420
 421 template<unsigned N>
 422 int_range<N>::int_range (tree min, tree max, value_range_kind kind)
 423   : irange (m_ranges, N)
 424 {
 425   irange::set (min, max, kind);
 426 }
 427
 428 template<unsigned N>
 429 int_range<N>::int_range (tree type)
 430   : irange (m_ranges, N)
 431 {
 432   set_varying (type);
 433 }
 434
 435 template<unsigned N>
 436 int_range<N>::int_range (tree type, const wide_int &wmin, const wide_int &wmax,
 437                          value_range_kind kind)
 438   : irange (m_ranges, N)
 439 {
 440   tree min = wide_int_to_tree (type, wmin);
 441   tree max = wide_int_to_tree (type, wmax);
 442   set (min, max, kind);
 443 }
 444
 445 template<unsigned N>
 446 int_range<N>::int_range (const irange &other)
 447   : irange (m_ranges, N)
 448 {
 449   irange::operator= (other);
 450 }
 451
 452 template<unsigned N>
 453 int_range<N>&
 454 int_range<N>::operator= (const int_range &src)
 455 {
 456   irange::operator= (src);
 457   return *this;
 458 }
 459
 460 inline void
 461 irange::set (tree val)
 462 {
 463   set (val, val);
 464 }
 465
 466 inline void
 467 irange::set_undefined ()
 468 {
 469   m_kind = VR_UNDEFINED;
 470   m_num_ranges = 0;
 471 }
 472
 473 inline void
 474 irange::set_varying (tree type)
 475 {
 476   m_kind = VR_VARYING;
 477   m_num_ranges = 1;
 478
 479   if (INTEGRAL_TYPE_P (type))
 480     {
 481       // Strict enum's require varying to be not TYPE_MIN/MAX, but rather
 482       // min_value and max_value.
 483       wide_int min = wi::min_value (TYPE_PRECISION (type), TYPE_SIGN (type));
 484       wide_int max = wi::max_value (TYPE_PRECISION (type), TYPE_SIGN (type));
 485       if (wi::eq_p (max, wi::to_wide (TYPE_MAX_VALUE (type)))
 486           && wi::eq_p (min, wi::to_wide (TYPE_MIN_VALUE (type))))
 487         {
 488           m_base[0] = TYPE_MIN_VALUE (type);
 489           m_base[1] = TYPE_MAX_VALUE (type);
 490         }
 491       else
 492         {
 493           m_base[0] = wide_int_to_tree (type, min);
 494           m_base[1] = wide_int_to_tree (type, max);
 495         }
 496     }
 497   else if (POINTER_TYPE_P (type))
 498     {
 499       m_base[0] = build_int_cst (type, 0);
 500       m_base[1] = build_int_cst (type, -1);
 501     }
 502   else
 503     m_base[0] = m_base[1] = error_mark_node;
 504 }
 505
 506 inline bool
 507 irange::operator== (const irange &r) const
 508 {
 509   return equal_p (r);
 510 }
 511
 512 // Return the lower bound of a sub-range.  PAIR is the sub-range in
 513 // question.
 514
 515 inline wide_int
 516 irange::lower_bound (unsigned pair) const
 517 {
 518   if (legacy_mode_p ())
 519     return legacy_lower_bound (pair);
 520   gcc_checking_assert (m_num_ranges > 0);
 521   gcc_checking_assert (pair + 1 <= num_pairs ());
 522   return wi::to_wide (tree_lower_bound (pair));
 523 }
 524
 525 // Return the upper bound of a sub-range.  PAIR is the sub-range in
 526 // question.
 527
 528 inline wide_int
 529 irange::upper_bound (unsigned pair) const
 530 {
 531   if (legacy_mode_p ())
 532     return legacy_upper_bound (pair);
 533   gcc_checking_assert (m_num_ranges > 0);
 534   gcc_checking_assert (pair + 1 <= num_pairs ());
 535   return wi::to_wide (tree_upper_bound (pair));
 536 }
 537
 538 // Return the highest bound of a range.
 539
 540 inline wide_int
 541 irange::upper_bound () const
 542 {
 543   unsigned pairs = num_pairs ();
 544   gcc_checking_assert (pairs > 0);
 545   return upper_bound (pairs - 1);
 546 }
 547
 548 inline void
 549 irange::union_ (const irange &r)
 550 {
 551   dump_flags_t m_flags = dump_flags;
 552   dump_flags &= ~TDF_DETAILS;
 553   irange::union_ (&r);
 554   dump_flags = m_flags;
 555 }
 556
 557 inline void
 558 irange::intersect (const irange &r)
 559 {
 560   dump_flags_t m_flags = dump_flags;
 561   dump_flags &= ~TDF_DETAILS;
 562   irange::intersect (&r);
 563   dump_flags = m_flags;
 564 }
 565
 566 // Set value range VR to a nonzero range of type TYPE.
 567
 568 inline void
 569 irange::set_nonzero (tree type)
 570 {
 571   tree zero = build_int_cst (type, 0);
 572   if (legacy_mode_p ())
 573     set (zero, zero, VR_ANTI_RANGE);
 574   else
 575     irange_set_anti_range (zero, zero);
 576 }
 577
 578 // Set value range VR to a ZERO range of type TYPE.
 579
 580 inline void
 581 irange::set_zero (tree type)
 582 {
 583   tree z = build_int_cst (type, 0);
 584   if (legacy_mode_p ())
 585     set (z);
 586   else
 587     irange_set (z, z);
 588 }
 589
 590 // Normalize a range to VARYING or UNDEFINED if possible.
 591
 592 inline void
 593 irange::normalize_kind ()
 594 {
 595   if (m_num_ranges == 0)
 596     m_kind = VR_UNDEFINED;
 597   else if (varying_compatible_p ())
 598     {
 599       if (m_kind == VR_RANGE)
 600         m_kind = VR_VARYING;
 601       else if (m_kind == VR_ANTI_RANGE)
 602         set_undefined ();
 603       else
 604         gcc_unreachable ();
 605     }
 606 }
 607
 608 // Return the maximum value for TYPE.
 609
 610 inline tree
 611 vrp_val_max (const_tree type)
 612 {
 613   if (INTEGRAL_TYPE_P (type))
 614     return TYPE_MAX_VALUE (type);
 615   if (POINTER_TYPE_P (type))
 616     {
 617       wide_int max = wi::max_value (TYPE_PRECISION (type), TYPE_SIGN (type));
 618       return wide_int_to_tree (const_cast<tree> (type), max);
 619     }
 620   return NULL_TREE;
 621 }
 622
 623 // Return the minimum value for TYPE.
 624
 625 inline tree
 626 vrp_val_min (const_tree type)
 627 {
 628   if (INTEGRAL_TYPE_P (type))
 629     return TYPE_MIN_VALUE (type);
 630   if (POINTER_TYPE_P (type))
 631     return build_zero_cst (const_cast<tree> (type));
 632   return NULL_TREE;
 633 }
 634
 635 // This is the irange storage class.  It is used to allocate the
 636 // minimum amount of storage needed for a given irange.  Storage is
 637 // automatically freed at destruction of the storage class.
 638 //
 639 // It is meant for long term storage, as opposed to int_range_max
 640 // which is meant for intermediate temporary results on the stack.
 641 //
 642 // The newly allocated irange is initialized to the empty set
 643 // (undefined_p() is true).
 644
 645 class irange_allocator
 646 {
 647 public:
 648   irange_allocator ();
 649   ~irange_allocator ();
 650   // Return a new range with NUM_PAIRS.
 651   irange *allocate (unsigned num_pairs);
 652   // Return a copy of SRC with the minimum amount of sub-ranges needed
 653   // to represent it.
 654   irange *allocate (const irange &src);
 655   void *get_memory (unsigned num_bytes);
 656 private:
 657   DISABLE_COPY_AND_ASSIGN (irange_allocator);
 658   struct obstack m_obstack;
 659 };
 660
 661 inline
 662 irange_allocator::irange_allocator ()
 663 {
 664   obstack_init (&m_obstack);
 665 }
 666
 667 inline
 668 irange_allocator::~irange_allocator ()
 669 {
 670   obstack_free (&m_obstack, NULL);
 671 }
 672
 673 // Provide a hunk of memory from the obstack.
 674 inline void *
 675 irange_allocator::get_memory (unsigned num_bytes)
 676 {
 677   void *r = obstack_alloc (&m_obstack, num_bytes);
 678   return r;
 679 }
 680
 681 // Return a new range with NUM_PAIRS.
 682
 683 inline irange *
 684 irange_allocator::allocate (unsigned num_pairs)
 685 {
 686   // Never allocate 0 pairs.
 687   // Don't allocate 1 either, or we get legacy value_range's.
 688   if (num_pairs < 2)
 689     num_pairs = 2;
 690
 691   size_t nbytes = sizeof (tree) * 2 * num_pairs;
 692
 693   // Allocate the irange and required memory for the vector.
 694   void *r = obstack_alloc (&m_obstack, sizeof (irange));
 695   tree *mem = (tree *) obstack_alloc (&m_obstack, nbytes);
 696   return new (r) irange (mem, num_pairs);
 697 }
 698
 699 inline irange *
 700 irange_allocator::allocate (const irange &src)
 701 {
 702   irange *r = allocate (src.num_pairs ());
 703   *r = src;
 704   return r;
 705 }
 706
 707 #endif // GCC_VALUE_RANGE_H