gcc/builtins.h

   1 /* Expand builtin functions.
   2    Copyright (C) 1988-2020 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_BUILTINS_H
  21 #define GCC_BUILTINS_H
  22
  23 #include <mpc.h>
  24
  25 /* Target-dependent globals.  */
  26 struct target_builtins {
  27   /* For each register that may be used for calling a function, this
  28      gives a mode used to copy the register's value.  VOIDmode indicates
  29      the register is not used for calling a function.  If the machine
  30      has register windows, this gives only the outbound registers.
  31      INCOMING_REGNO gives the corresponding inbound register.  */
  32   fixed_size_mode_pod x_apply_args_mode[FIRST_PSEUDO_REGISTER];
  33
  34   /* For each register that may be used for returning values, this gives
  35      a mode used to copy the register's value.  VOIDmode indicates the
  36      register is not used for returning values.  If the machine has
  37      register windows, this gives only the outbound registers.
  38      INCOMING_REGNO gives the corresponding inbound register.  */
  39   fixed_size_mode_pod x_apply_result_mode[FIRST_PSEUDO_REGISTER];
  40 };
  41
  42 extern struct target_builtins default_target_builtins;
  43 #if SWITCHABLE_TARGET
  44 extern struct target_builtins *this_target_builtins;
  45 #else
  46 #define this_target_builtins (&default_target_builtins)
  47 #endif
  48
  49 /* Non-zero if __builtin_constant_p should be folded right away.  */
  50 extern bool force_folding_builtin_constant_p;
  51
  52 extern bool called_as_built_in (tree);
  53 extern bool get_object_alignment_1 (tree, unsigned int *,
  54                                     unsigned HOST_WIDE_INT *);
  55 extern unsigned int get_object_alignment (tree);
  56 extern bool get_pointer_alignment_1 (tree, unsigned int *,
  57                                      unsigned HOST_WIDE_INT *);
  58 extern unsigned int get_pointer_alignment (tree);
  59 extern unsigned string_length (const void*, unsigned, unsigned);
  60
  61 struct c_strlen_data
  62 {
  63   /* [MINLEN, MAXBOUND, MAXLEN] is a range describing the length of
  64      one or more strings of possibly unknown length.  For a single
  65      string of known length the range is a constant where
  66      MINLEN == MAXBOUND == MAXLEN holds.
  67      For other strings, MINLEN is the length of the shortest known
  68      string.  MAXBOUND is the length of a string that could be stored
  69      in the largest array referenced by the expression.  MAXLEN is
  70      the length of the longest sequence of non-zero bytes
  71      in an object referenced by the expression.  For such strings,
  72      MINLEN <= MAXBOUND <= MAXLEN holds.  For example, given:
  73        struct A { char a[7], b[]; };
  74        extern struct A *p;
  75        n = strlen (p->a);
  76      the computed range will be [0, 6, ALL_ONES].
  77      However, for a conditional expression involving a string
  78      of known length and an array of unknown bound such as
  79        n = strlen (i ? p->b : "123");
  80      the range will be [3, 3, ALL_ONES].
  81      MINLEN != 0 && MAXLEN == ALL_ONES indicates that MINLEN is
  82      the length of the shortest known string and implies that
  83      the shortest possible string referenced by the expression may
  84      actually be the empty string.  This distinction is useful for
  85      diagnostics.  get_range_strlen() return value distinguishes
  86      between these two cases.
  87      As the tighter (and more optimistic) bound, MAXBOUND is suitable
  88      for diagnostics but not for optimization.
  89      As the more conservative bound, MAXLEN is intended to be used
  90      for optimization.  */
  91   tree minlen;
  92   tree maxlen;
  93   tree maxbound;
  94   /* When non-null, DECL refers to the declaration known to store
  95      an unterminated constant character array, as in:
  96      const char s[] = { 'a', 'b', 'c' };
  97      It is used to diagnose uses of such arrays in functions such as
  98      strlen() that expect a nul-terminated string as an argument.  */
  99   tree decl;
 100   /* Non-constant offset from the beginning of a string not accounted
 101      for in the length range.  Used to improve diagnostics.  */
 102   tree off;
 103 };
 104
 105 extern tree c_strlen (tree, int, c_strlen_data * = NULL, unsigned = 1);
 106 extern rtx c_readstr (const char *, scalar_int_mode, bool = true);
 107 extern void expand_builtin_setjmp_setup (rtx, rtx);
 108 extern void expand_builtin_setjmp_receiver (rtx);
 109 extern void expand_builtin_update_setjmp_buf (rtx);
 110 extern tree mathfn_built_in (tree, enum built_in_function fn);
 111 extern tree mathfn_built_in (tree, combined_fn);
 112 extern tree mathfn_built_in_type (combined_fn);
 113 extern rtx builtin_strncpy_read_str (void *, HOST_WIDE_INT, scalar_int_mode);
 114 extern rtx builtin_memset_read_str (void *, HOST_WIDE_INT, scalar_int_mode);
 115 extern rtx expand_builtin_saveregs (void);
 116 extern tree std_build_builtin_va_list (void);
 117 extern tree std_fn_abi_va_list (tree);
 118 extern tree std_canonical_va_list_type (tree);
 119 extern void std_expand_builtin_va_start (tree, rtx);
 120 extern void expand_builtin_trap (void);
 121 extern void expand_ifn_atomic_bit_test_and (gcall *);
 122 extern void expand_ifn_atomic_compare_exchange (gcall *);
 123 extern rtx expand_builtin (tree, rtx, rtx, machine_mode, int);
 124 extern enum built_in_function builtin_mathfn_code (const_tree);
 125 extern tree fold_builtin_expect (location_t, tree, tree, tree, tree);
 126 extern bool avoid_folding_inline_builtin (tree);
 127 extern tree fold_call_expr (location_t, tree, bool);
 128 extern tree fold_builtin_call_array (location_t, tree, tree, int, tree *);
 129 extern bool validate_gimple_arglist (const gcall *, ...);
 130 extern rtx default_expand_builtin (tree, rtx, rtx, machine_mode, int);
 131 extern void maybe_emit_call_builtin___clear_cache (rtx, rtx);
 132 extern bool fold_builtin_next_arg (tree, bool);
 133 extern tree do_mpc_arg2 (tree, tree, tree, int, int (*)(mpc_ptr, mpc_srcptr, mpc_srcptr, mpc_rnd_t));
 134 extern tree fold_call_stmt (gcall *, bool);
 135 extern void set_builtin_user_assembler_name (tree decl, const char *asmspec);
 136 extern bool is_simple_builtin (tree);
 137 extern bool is_inexpensive_builtin (tree);
 138 extern bool readonly_data_expr (tree exp);
 139 extern bool init_target_chars (void);
 140 extern unsigned HOST_WIDE_INT target_newline;
 141 extern unsigned HOST_WIDE_INT target_percent;
 142 extern char target_percent_s[3];
 143 extern char target_percent_c[3];
 144 extern char target_percent_s_newline[4];
 145 extern bool target_char_cst_p (tree t, char *p);
 146
 147 extern internal_fn associated_internal_fn (tree);
 148 extern internal_fn replacement_internal_fn (gcall *);
 149
 150 extern bool check_nul_terminated_array (tree, tree, tree = NULL_TREE);
 151 extern void warn_string_no_nul (location_t, tree, const char *, tree,
 152                                 tree, tree = NULL_TREE, bool = false,
 153                                 const wide_int[2] = NULL);
 154 extern tree unterminated_array (tree, tree * = NULL, bool * = NULL);
 155 extern bool builtin_with_linkage_p (tree);
 156
 157 /* Describes recursion limits used by functions that follow use-def
 158    chains of SSA_NAMEs.  */
 159
 160 class ssa_name_limit_t
 161 {
 162   bitmap visited;         /* Bitmap of visited SSA_NAMEs.  */
 163   unsigned ssa_def_max;   /* Longest chain of SSA_NAMEs to follow.  */
 164
 165   /* Not copyable or assignable.  */
 166   DISABLE_COPY_AND_ASSIGN (ssa_name_limit_t);
 167
 168 public:
 169
 170   ssa_name_limit_t ()
 171     : visited (),
 172       ssa_def_max (param_ssa_name_def_chain_limit) { }
 173
 174   /* Set a bit for the PHI in VISITED and return true if it wasn't
 175      already set.  */
 176   bool visit_phi (tree);
 177   /* Clear a bit for the PHI in VISITED.  */
 178   void leave_phi (tree);
 179   /* Return false if the SSA_NAME chain length counter has reached
 180      the limit, otherwise increment the counter and return true.  */
 181   bool next ();
 182
 183   /* If the SSA_NAME has already been "seen" return a positive value.
 184      Otherwise add it to VISITED.  If the SSA_NAME limit has been
 185      reached, return a negative value.  Otherwise return zero.  */
 186   int next_phi (tree);
 187
 188   ~ssa_name_limit_t ();
 189 };
 190
 191 class pointer_query;
 192
 193 /* Describes a reference to an object used in an access.  */
 194 struct access_ref
 195 {
 196   /* Set the bounds of the reference to at most as many bytes
 197      as the first argument or unknown when null, and at least
 198      one when the second argument is true unless the first one
 199      is a constant zero.  */
 200   access_ref (tree = NULL_TREE, bool = false);
 201
 202   /* Return the PHI node REF refers to or null if it doesn't.  */
 203   gphi *phi () const;
 204
 205   /* Return the object to which REF refers.  */
 206   tree get_ref (vec<access_ref> *, access_ref * = NULL, int = 1,
 207                 ssa_name_limit_t * = NULL, pointer_query * = NULL) const;
 208
 209   /* Return true if OFFRNG is the constant zero.  */
 210   bool offset_zero () const
 211   {
 212     return offrng[0] == 0 && offrng[1] == 0;
 213   }
 214
 215   /* Return true if OFFRNG is bounded to a subrange of offset values
 216      valid for the largest possible object.  */
 217   bool offset_bounded () const;
 218
 219   /* Return the maximum amount of space remaining and if non-null, set
 220      argument to the minimum.  */
 221   offset_int size_remaining (offset_int * = NULL) const;
 222
 223   /* Return true if *THIS is an access to a declared object.  */
 224   bool ref_declared () const
 225   {
 226     return DECL_P (ref) && base0 && deref < 1;
 227   }
 228
 229   /* Set the size range to the maximum.  */
 230   void set_max_size_range ()
 231   {
 232     sizrng[0] = 0;
 233     sizrng[1] = wi::to_offset (max_object_size ());
 234   }
 235
 236   /* Add OFF to the offset range.  */
 237   void add_offset (const offset_int &off)
 238   {
 239     add_offset (off, off);
 240   }
 241
 242   /* Add the range [MIN, MAX] to the offset range.  */
 243   void add_offset (const offset_int &, const offset_int &);
 244
 245   /* Add the maximum representable offset to the offset range.  */
 246   void add_max_offset ()
 247   {
 248     offset_int maxoff = wi::to_offset (TYPE_MAX_VALUE (ptrdiff_type_node));
 249     add_offset (-maxoff - 1, maxoff);
 250   }
 251
 252   /* Issue an informational message describing the target of an access
 253      with the given mode.  */
 254   void inform_access (access_mode) const;
 255
 256   /* Reference to the accessed object(s).  */
 257   tree ref;
 258
 259   /* Range of byte offsets into and sizes of the object(s).  */
 260   offset_int offrng[2];
 261   offset_int sizrng[2];
 262   /* Range of the bound of the access: denotes that the access
 263      is at least BNDRNG[0] bytes but no more than BNDRNG[1].
 264      For string functions the size of the actual access is
 265      further constrained by the length of the string.  */
 266   offset_int bndrng[2];
 267
 268   /* Used to fold integer expressions when called from front ends.  */
 269   tree (*eval)(tree);
 270   /* Positive when REF is dereferenced, negative when its address is
 271      taken.  */
 272   int deref;
 273   /* Set if trailing one-element arrays should be treated as flexible
 274      array members.  */
 275   bool trail1special;
 276   /* Set if valid offsets must start at zero (for declared and allocated
 277      objects but not for others referenced by pointers).  */
 278   bool base0;
 279   /* Set if REF refers to a function array parameter not declared
 280      static.  */
 281   bool parmarray;
 282 };
 283
 284 class range_query;
 285
 286 /* Queries and caches compute_objsize results.  */
 287 class pointer_query
 288 {
 289   DISABLE_COPY_AND_ASSIGN (pointer_query);
 290
 291 public:
 292   /* Type of the two-level cache object defined by clients of the class
 293      to have pointer SSA_NAMEs cached for speedy access.  */
 294   struct cache_type
 295   {
 296     /* 1-based indices into cache.  */
 297     vec<unsigned> indices;
 298     /* The cache itself.  */
 299     vec<access_ref> access_refs;
 300   };
 301
 302   /* Construct an object with the given Ranger instance and cache.  */
 303   explicit pointer_query (range_query * = NULL, cache_type * = NULL);
 304
 305   /* Retrieve the access_ref for a variable from cache if it's there.  */
 306   const access_ref* get_ref (tree, int = 1) const;
 307
 308   /* Retrieve the access_ref for a variable from cache or compute it.  */
 309   bool get_ref (tree, access_ref*, int = 1);
 310
 311   /* Add an access_ref for the SSA_NAME to the cache.  */
 312   void put_ref (tree, const access_ref&, int = 1);
 313
 314   /* Flush the cache.  */
 315   void flush_cache ();
 316
 317   /* A Ranger instance.  May be null to use global ranges.  */
 318   range_query *rvals;
 319   /* Cache of SSA_NAMEs.  May be null to disable caching.  */
 320   cache_type *var_cache;
 321
 322   /* Cache performance counters.  */
 323   mutable unsigned hits;
 324   mutable unsigned misses;
 325   mutable unsigned failures;
 326   mutable unsigned depth;
 327   mutable unsigned max_depth;
 328 };
 329
 330 /* Describes a pair of references used in an access by built-in
 331    functions like memcpy.  */
 332 struct access_data
 333 {
 334   /* Set the access to at most MAXWRITE and MAXREAD bytes, and
 335      at least 1 when MINWRITE or MINREAD, respectively, is set.  */
 336   access_data (tree expr, access_mode mode,
 337                tree maxwrite = NULL_TREE, bool minwrite = false,
 338                tree maxread = NULL_TREE, bool minread = false)
 339     : call (expr),
 340       dst (maxwrite, minwrite), src (maxread, minread), mode (mode) { }
 341
 342   /* Built-in function call.  */
 343   tree call;
 344   /* Destination and source of the access.  */
 345   access_ref dst, src;
 346   /* Read-only for functions like memcmp or strlen, write-only
 347      for memset, read-write for memcpy or strcat.  */
 348   access_mode mode;
 349 };
 350
 351 extern tree gimple_call_alloc_size (gimple *, wide_int[2] = NULL,
 352                                     range_query * = NULL);
 353 extern tree gimple_parm_array_size (tree, wide_int[2], bool * = NULL);
 354
 355 extern tree compute_objsize (tree, int, access_ref *, range_query * = NULL);
 356 /* Legacy/transitional API.  Should not be used in new code.  */
 357 extern tree compute_objsize (tree, int, access_ref *, pointer_query *);
 358 extern tree compute_objsize (tree, int, tree * = NULL, tree * = NULL,
 359                              range_query * = NULL);
 360 extern bool check_access (tree, tree, tree, tree, tree,
 361                           access_mode, const access_data * = NULL);
 362 extern void maybe_emit_free_warning (tree);
 363
 364 #endif /* GCC_BUILTINS_H */