gcc/analyzer/analyzer.cc

   1 /* Utility functions for the analyzer.
   2    Copyright (C) 2019-2022 Free Software Foundation, Inc.
   3    Contributed by David Malcolm <dmalcolm@redhat.com>.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it
   8 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, but
  13 WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15 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 "tree.h"
  25 #include "function.h"
  26 #include "basic-block.h"
  27 #include "gimple.h"
  28 #include "diagnostic.h"
  29 #include "intl.h"
  30 #include "function.h"
  31 #include "analyzer/analyzer.h"
  32
  33 #if ENABLE_ANALYZER
  34
  35 namespace ana {
  36
  37 /* Workaround for missing location information for some stmts,
  38    which ultimately should be solved by fixing the frontends
  39    to provide the locations (TODO).  */
  40
  41 location_t
  42 get_stmt_location (const gimple *stmt, function *fun)
  43 {
  44   if (get_pure_location (stmt->location) == UNKNOWN_LOCATION)
  45     {
  46       /* Workaround for missing location information for clobber
  47          stmts, which seem to lack location information in the C frontend
  48          at least.  Created by gimplify_bind_expr, which uses the
  49            BLOCK_SOURCE_END_LOCATION (BIND_EXPR_BLOCK (bind_expr))
  50          but this is never set up when the block is created in
  51          c_end_compound_stmt's pop_scope.
  52          TODO: fix this missing location information.
  53
  54          For now, as a hackish workaround, use the location of the end of
  55          the function.  */
  56       if (gimple_clobber_p (stmt) && fun)
  57         return fun->function_end_locus;
  58     }
  59
  60   return stmt->location;
  61 }
  62
  63 static tree
  64 fixup_tree_for_diagnostic_1 (tree expr, hash_set<tree> *visited);
  65
  66 /* Attemp to generate a tree for the LHS of ASSIGN_STMT.
  67    VISITED must be non-NULL; it is used to ensure termination.  */
  68
  69 static tree
  70 get_diagnostic_tree_for_gassign_1 (const gassign *assign_stmt,
  71                                    hash_set<tree> *visited)
  72 {
  73   enum tree_code code = gimple_assign_rhs_code (assign_stmt);
  74
  75   /* Reverse the effect of extract_ops_from_tree during
  76      gimplification.  */
  77   switch (get_gimple_rhs_class (code))
  78     {
  79     default:
  80     case GIMPLE_INVALID_RHS:
  81       gcc_unreachable ();
  82     case GIMPLE_TERNARY_RHS:
  83     case GIMPLE_BINARY_RHS:
  84     case GIMPLE_UNARY_RHS:
  85       {
  86         tree t = make_node (code);
  87         TREE_TYPE (t) = TREE_TYPE (gimple_assign_lhs (assign_stmt));
  88         unsigned num_rhs_args = gimple_num_ops (assign_stmt) - 1;
  89         for (unsigned i = 0; i < num_rhs_args; i++)
  90           {
  91             tree op = gimple_op (assign_stmt, i + 1);
  92             if (op)
  93               {
  94                 op = fixup_tree_for_diagnostic_1 (op, visited);
  95                 if (op == NULL_TREE)
  96                   return NULL_TREE;
  97               }
  98             TREE_OPERAND (t, i) = op;
  99           }
 100         return t;
 101       }
 102     case GIMPLE_SINGLE_RHS:
 103       {
 104         tree op = gimple_op (assign_stmt, 1);
 105         op = fixup_tree_for_diagnostic_1 (op, visited);
 106         return op;
 107       }
 108     }
 109 }
 110
 111 /*  Subroutine of fixup_tree_for_diagnostic_1, called on SSA names.
 112     Attempt to reconstruct a a tree expression for SSA_NAME
 113     based on its def-stmt.
 114     SSA_NAME must be non-NULL.
 115     VISITED must be non-NULL; it is used to ensure termination.
 116
 117     Return NULL_TREE if there is a problem.  */
 118
 119 static tree
 120 maybe_reconstruct_from_def_stmt (tree ssa_name,
 121                                  hash_set<tree> *visited)
 122 {
 123   /* Ensure termination.  */
 124   if (visited->contains (ssa_name))
 125     return NULL_TREE;
 126   visited->add (ssa_name);
 127
 128   gimple *def_stmt = SSA_NAME_DEF_STMT (ssa_name);
 129
 130   switch (gimple_code (def_stmt))
 131     {
 132     default:
 133       gcc_unreachable ();
 134     case GIMPLE_ASM:
 135     case GIMPLE_NOP:
 136     case GIMPLE_PHI:
 137       /* Can't handle these.  */
 138       return NULL_TREE;
 139     case GIMPLE_ASSIGN:
 140       return get_diagnostic_tree_for_gassign_1
 141         (as_a <const gassign *> (def_stmt), visited);
 142     case GIMPLE_CALL:
 143       {
 144         gcall *call_stmt = as_a <gcall *> (def_stmt);
 145         tree return_type = gimple_call_return_type (call_stmt);
 146         tree fn = fixup_tree_for_diagnostic_1 (gimple_call_fn (call_stmt),
 147                                                visited);
 148         if (fn == NULL_TREE)
 149           return NULL_TREE;
 150         unsigned num_args = gimple_call_num_args (call_stmt);
 151         auto_vec<tree> args (num_args);
 152         for (unsigned i = 0; i < num_args; i++)
 153           {
 154             tree arg = gimple_call_arg (call_stmt, i);
 155             arg = fixup_tree_for_diagnostic_1 (arg, visited);
 156             if (arg == NULL_TREE)
 157               return NULL_TREE;
 158             args.quick_push (arg);
 159           }
 160         gcc_assert (fn);
 161         return build_call_array_loc (gimple_location (call_stmt),
 162                                      return_type, fn,
 163                                      num_args, args.address ());
 164       }
 165       break;
 166     }
 167 }
 168
 169 /* Subroutine of fixup_tree_for_diagnostic: attempt to fixup EXPR,
 170    which can be NULL.
 171    VISITED must be non-NULL; it is used to ensure termination.  */
 172
 173 static tree
 174 fixup_tree_for_diagnostic_1 (tree expr, hash_set<tree> *visited)
 175 {
 176   if (expr
 177       && TREE_CODE (expr) == SSA_NAME
 178       && (SSA_NAME_VAR (expr) == NULL_TREE
 179           || DECL_ARTIFICIAL (SSA_NAME_VAR (expr))))
 180     {
 181       if (tree var = SSA_NAME_VAR (expr))
 182         if (VAR_P (var) && DECL_HAS_DEBUG_EXPR_P (var))
 183           return DECL_DEBUG_EXPR (var);
 184       if (tree expr2 = maybe_reconstruct_from_def_stmt (expr, visited))
 185         return expr2;
 186     }
 187   return expr;
 188 }
 189
 190 /* We don't want to print '<unknown>' in our diagnostics (PR analyzer/99771),
 191    but sometimes we generate diagnostics involving an ssa name for a
 192    temporary.
 193
 194    Work around this by attempting to reconstruct a tree expression for
 195    such temporaries based on their def-stmts.
 196
 197    Otherwise return EXPR.
 198
 199    EXPR can be NULL.  */
 200
 201 tree
 202 fixup_tree_for_diagnostic (tree expr)
 203 {
 204   hash_set<tree> visited;
 205   return fixup_tree_for_diagnostic_1 (expr, &visited);
 206 }
 207
 208 /* Attempt to generate a tree for the LHS of ASSIGN_STMT.  */
 209
 210 tree
 211 get_diagnostic_tree_for_gassign (const gassign *assign_stmt)
 212 {
 213   hash_set<tree> visited;
 214   return get_diagnostic_tree_for_gassign_1 (assign_stmt, &visited);
 215 }
 216
 217 } // namespace ana
 218
 219 /* Helper function for checkers.  Is the CALL to the given function name,
 220    and with the given number of arguments?
 221
 222    This doesn't resolve function pointers via the region model;
 223    is_named_call_p should be used instead, using a fndecl from
 224    get_fndecl_for_call; this function should only be used for special cases
 225    where it's not practical to get at the region model, or for special
 226    analyzer functions such as __analyzer_dump.  */
 227
 228 bool
 229 is_special_named_call_p (const gcall *call, const char *funcname,
 230                          unsigned int num_args)
 231 {
 232   gcc_assert (funcname);
 233
 234   tree fndecl = gimple_call_fndecl (call);
 235   if (!fndecl)
 236     return false;
 237
 238   return is_named_call_p (fndecl, funcname, call, num_args);
 239 }
 240
 241 /* Helper function for checkers.  Is FNDECL an extern fndecl at file scope
 242    that has the given FUNCNAME?
 243
 244    Compare with special_function_p in calls.c.  */
 245
 246 bool
 247 is_named_call_p (const_tree fndecl, const char *funcname)
 248 {
 249   gcc_assert (fndecl);
 250   gcc_assert (funcname);
 251
 252   if (!maybe_special_function_p (fndecl))
 253     return false;
 254
 255   tree identifier = DECL_NAME (fndecl);
 256   const char *name = IDENTIFIER_POINTER (identifier);
 257   const char *tname = name;
 258
 259   /* Potentially disregard prefix _ or __ in FNDECL's name, but not if
 260      FUNCNAME itself has leading underscores (e.g. when looking for
 261      "__analyzer_eval").  */
 262   if (funcname[0] != '_' && name[0] == '_')
 263     {
 264       if (name[1] == '_')
 265         tname += 2;
 266       else
 267         tname += 1;
 268     }
 269
 270   return 0 == strcmp (tname, funcname);
 271 }
 272
 273 /* Return true if FNDECL is within the namespace "std".
 274    Compare with cp/typeck.c: decl_in_std_namespace_p, but this doesn't
 275    rely on being the C++ FE (or handle inline namespaces inside of std).  */
 276
 277 static inline bool
 278 is_std_function_p (const_tree fndecl)
 279 {
 280   tree name_decl = DECL_NAME (fndecl);
 281   if (!name_decl)
 282     return false;
 283   if (!DECL_CONTEXT (fndecl))
 284     return false;
 285   if (TREE_CODE (DECL_CONTEXT (fndecl)) != NAMESPACE_DECL)
 286     return false;
 287   tree ns = DECL_CONTEXT (fndecl);
 288   if (!(DECL_CONTEXT (ns) == NULL_TREE
 289         || TREE_CODE (DECL_CONTEXT (ns)) == TRANSLATION_UNIT_DECL))
 290     return false;
 291   if (!DECL_NAME (ns))
 292     return false;
 293   return id_equal ("std", DECL_NAME (ns));
 294 }
 295
 296 /* Like is_named_call_p, but look for std::FUNCNAME.  */
 297
 298 bool
 299 is_std_named_call_p (const_tree fndecl, const char *funcname)
 300 {
 301   gcc_assert (fndecl);
 302   gcc_assert (funcname);
 303
 304   if (!is_std_function_p (fndecl))
 305     return false;
 306
 307   tree identifier = DECL_NAME (fndecl);
 308   const char *name = IDENTIFIER_POINTER (identifier);
 309   const char *tname = name;
 310
 311   /* Don't disregard prefix _ or __ in FNDECL's name.  */
 312
 313   return 0 == strcmp (tname, funcname);
 314 }
 315
 316 /* Helper function for checkers.  Is FNDECL an extern fndecl at file scope
 317    that has the given FUNCNAME, and does CALL have the given number of
 318    arguments?  */
 319
 320 bool
 321 is_named_call_p (const_tree fndecl, const char *funcname,
 322                  const gcall *call, unsigned int num_args)
 323 {
 324   gcc_assert (fndecl);
 325   gcc_assert (funcname);
 326
 327   if (!is_named_call_p (fndecl, funcname))
 328     return false;
 329
 330   if (gimple_call_num_args (call) != num_args)
 331     return false;
 332
 333   return true;
 334 }
 335
 336 /* Like is_named_call_p, but check for std::FUNCNAME.  */
 337
 338 bool
 339 is_std_named_call_p (const_tree fndecl, const char *funcname,
 340                      const gcall *call, unsigned int num_args)
 341 {
 342   gcc_assert (fndecl);
 343   gcc_assert (funcname);
 344
 345   if (!is_std_named_call_p (fndecl, funcname))
 346     return false;
 347
 348   if (gimple_call_num_args (call) != num_args)
 349     return false;
 350
 351   return true;
 352 }
 353
 354 /* Return true if stmt is a setjmp or sigsetjmp call.  */
 355
 356 bool
 357 is_setjmp_call_p (const gcall *call)
 358 {
 359   if (is_special_named_call_p (call, "setjmp", 1)
 360       || is_special_named_call_p (call, "sigsetjmp", 2))
 361     /* region_model::on_setjmp requires a pointer.  */
 362     if (POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call, 0))))
 363       return true;
 364
 365   return false;
 366 }
 367
 368 /* Return true if stmt is a longjmp or siglongjmp call.  */
 369
 370 bool
 371 is_longjmp_call_p (const gcall *call)
 372 {
 373   if (is_special_named_call_p (call, "longjmp", 2)
 374       || is_special_named_call_p (call, "siglongjmp", 2))
 375     /* exploded_node::on_longjmp requires a pointer for the initial
 376        argument.  */
 377     if (POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call, 0))))
 378       return true;
 379
 380   return false;
 381 }
 382
 383 /* For a CALL that matched is_special_named_call_p or is_named_call_p for
 384    some name, return a name for the called function suitable for use in
 385    diagnostics (stripping the leading underscores).  */
 386
 387 const char *
 388 get_user_facing_name (const gcall *call)
 389 {
 390   tree fndecl = gimple_call_fndecl (call);
 391   gcc_assert (fndecl);
 392
 393   tree identifier = DECL_NAME (fndecl);
 394   gcc_assert (identifier);
 395
 396   const char *name = IDENTIFIER_POINTER (identifier);
 397
 398   /* Strip prefix _ or __ in FNDECL's name.  */
 399   if (name[0] == '_')
 400     {
 401       if (name[1] == '_')
 402         return name + 2;
 403       else
 404         return name + 1;
 405     }
 406
 407   return name;
 408 }
 409
 410 /* Generate a label_text instance by formatting FMT, using a
 411    temporary clone of the global_dc's printer (thus using its
 412    formatting callbacks).
 413
 414    Colorize if the global_dc supports colorization and CAN_COLORIZE is
 415    true.  */
 416
 417 label_text
 418 make_label_text (bool can_colorize, const char *fmt, ...)
 419 {
 420   pretty_printer *pp = global_dc->printer->clone ();
 421   pp_clear_output_area (pp);
 422
 423   if (!can_colorize)
 424     pp_show_color (pp) = false;
 425
 426   text_info ti;
 427   rich_location rich_loc (line_table, UNKNOWN_LOCATION);
 428
 429   va_list ap;
 430
 431   va_start (ap, fmt);
 432
 433   ti.format_spec = _(fmt);
 434   ti.args_ptr = &ap;
 435   ti.err_no = 0;
 436   ti.x_data = NULL;
 437   ti.m_richloc = &rich_loc;
 438
 439   pp_format (pp, &ti);
 440   pp_output_formatted_text (pp);
 441
 442   va_end (ap);
 443
 444   label_text result = label_text::take (xstrdup (pp_formatted_text (pp)));
 445   delete pp;
 446   return result;
 447 }
 448
 449 #endif /* #if ENABLE_ANALYZER */