gdb/macrotab.h

   1 /* Interface to C preprocessor macro tables for GDB.
   2    Copyright (C) 2002, 2007, 2008, 2009, 2010, 2011
   3    Free Software Foundation, Inc.
   4    Contributed by Red Hat, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program 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 of the License, or
  11    (at your option) any later version.
  12
  13    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #ifndef MACROTAB_H
  22 #define MACROTAB_H
  23
  24 struct obstack;
  25 struct bcache;
  26
  27 /* How do we represent a source location?  I mean, how should we
  28    represent them within GDB; the user wants to use all sorts of
  29    ambiguous abbreviations, like "break 32" and "break foo.c:32"
  30    ("foo.c" may have been #included into several compilation units),
  31    but what do we disambiguate those things to?
  32
  33    - Answer 1: "Filename and line number."  (Or column number, if
  34    you're picky.)  That's not quite good enough.  For example, the
  35    same source file can be #included into several different
  36    compilation units --- which #inclusion do you mean?
  37
  38    - Answer 2: "Compilation unit, filename, and line number."  This is
  39    a pretty good answer; GDB's `struct symtab_and_line' basically
  40    embodies this representation.  But it's still ambiguous; what if a
  41    given compilation unit #includes the same file twice --- how can I
  42    set a breakpoint on line 12 of the fifth #inclusion of "foo.c"?
  43
  44    - Answer 3: "Compilation unit, chain of #inclusions, and line
  45    number."  This is analogous to the way GCC reports errors in
  46    #include files:
  47
  48         $ gcc -c base.c
  49         In file included from header2.h:8,
  50                          from header1.h:3,
  51                          from base.c:5:
  52         header3.h:1: parse error before ')' token
  53         $
  54
  55    GCC tells you exactly what path of #inclusions led you to the
  56    problem.  It gives you complete information, in a way that the
  57    following would not:
  58
  59         $ gcc -c base.c
  60         header3.h:1: parse error before ')' token
  61         $
  62
  63    Converting all of GDB to use this is a big task, and I'm not really
  64    suggesting it should be a priority.  But this module's whole
  65    purpose is to maintain structures describing the macro expansion
  66    process, so I think it's appropriate for us to take a little care
  67    to do that in a complete fashion.
  68
  69    In this interface, the first line of a file is numbered 1, not 0.
  70    This is the same convention the rest of GDB uses.  */
  71
  72
  73 /* A table of all the macro definitions for a given compilation unit.  */
  74 struct macro_table;
  75
  76 /* The definition of a single macro.  */
  77 struct macro_definition;
  78
  79 /* A source file that participated in a compilation unit --- either a
  80    main file, or an #included file.  If a file is #included more than
  81    once, the presence of the `included_from' and `included_at_line'
  82    members means that we need to make one instance of this structure
  83    for each #inclusion.  Taken as a group, these structures form a
  84    tree mapping the #inclusions that contributed to the compilation
  85    unit, with the main source file as its root.
  86
  87    Beware --- not every source file mentioned in a compilation unit's
  88    symtab structures will appear in the #inclusion tree!  As of Oct
  89    2002, GCC does record the effect of #line directives in the source
  90    line info, but not in macro info.  This means that GDB's symtabs
  91    (built from the former, among other things) may mention filenames
  92    that the #inclusion tree (built from the latter) doesn't have any
  93    record of.  See macroscope.c:sal_macro_scope for how to accomodate
  94    this.
  95
  96    It's worth noting that libcpp has a simpler way of representing all
  97    this, which we should consider switching to.  It might even be
  98    suitable for ordinary non-macro line number info.
  99
 100    Suppose you take your main source file, and after each line
 101    containing an #include directive you insert the text of the
 102    #included file.  The result is a big file that pretty much
 103    corresponds to the full text the compiler's going to see.  There's
 104    a one-to-one correspondence between lines in the big file and
 105    per-inclusion lines in the source files.  (Obviously, #include
 106    directives that are #if'd out don't count.  And you'll need to
 107    append a newline to any file that doesn't end in one, to avoid
 108    splicing the last #included line with the next line of the
 109    #including file.)
 110
 111    Libcpp calls line numbers in this big imaginary file "logical line
 112    numbers", and has a data structure called a "line map" that can map
 113    logical line numbers onto actual source filenames and line numbers,
 114    and also tell you the chain of #inclusions responsible for any
 115    particular logical line number.  Basically, this means you can pass
 116    around a single line number and some kind of "compilation unit"
 117    object and you get nice, unambiguous source code locations that
 118    distinguish between multiple #inclusions of the same file, etc.
 119
 120    Pretty neat, huh?  */
 121
 122 struct macro_source_file
 123 {
 124
 125   /* The macro table for the compilation unit this source location is
 126      a part of.  */
 127   struct macro_table *table;
 128
 129   /* A source file --- possibly a header file.  */
 130   const char *filename;
 131
 132   /* The location we were #included from, or zero if we are the
 133      compilation unit's main source file.  */
 134   struct macro_source_file *included_by;
 135
 136   /* If `included_from' is non-zero, the line number in that source
 137      file at which we were included.  */
 138   int included_at_line;
 139
 140   /* Head of a linked list of the source files #included by this file;
 141      our children in the #inclusion tree.  This list is sorted by its
 142      elements' `included_at_line' values, which are unique.  (The
 143      macro splay tree's ordering function needs this property.)  */
 144   struct macro_source_file *includes;
 145
 146   /* The next file #included by our `included_from' file; our sibling
 147      in the #inclusion tree.  */
 148   struct macro_source_file *next_included;
 149 };
 150
 151
 152 /* Create a new, empty macro table.  Allocate it in OBSTACK, or use
 153    xmalloc if OBSTACK is zero.  Use BCACHE to store all macro names,
 154    arguments, definitions, and anything else that might be the same
 155    amongst compilation units in an executable file; if BCACHE is zero,
 156    don't cache these things.
 157
 158    Note that, if either OBSTACK or BCACHE are non-zero, then removing
 159    information from the table may leak memory.  Neither obstacks nor
 160    bcaches really allow you to remove information, so although we can
 161    update the data structure to record the change, we can't free the
 162    old data.  At the moment, since we only provide obstacks and
 163    bcaches for macro tables for symtabs, this isn't a problem; only
 164    odd debugging information makes a definition and then deletes it at
 165    the same source location (although 'gcc -DFOO -UFOO -DFOO=2' does
 166    do that in GCC 4.1.2.).  */
 167 struct macro_table *new_macro_table (struct obstack *obstack,
 168                                      struct bcache *bcache);
 169
 170
 171 /* Free TABLE, and any macro definitions, source file structures,
 172    etc. it owns.  This will raise an internal error if TABLE was
 173    allocated on an obstack, or if it uses a bcache.  */
 174 void free_macro_table (struct macro_table *table);
 175
 176
 177 /* Set FILENAME as the main source file of TABLE.  Return a source
 178    file structure describing that file; if we record the #definition
 179    of macros, or the #inclusion of other files into FILENAME, we'll
 180    use that source file structure to indicate the context.
 181
 182    The "main source file" is the one that was given to the compiler;
 183    all other source files that contributed to the compilation unit are
 184    #included, directly or indirectly, from this one.
 185
 186    The macro table makes its own copy of FILENAME; the caller is
 187    responsible for freeing FILENAME when it is no longer needed.  */
 188 struct macro_source_file *macro_set_main (struct macro_table *table,
 189                                           const char *filename);
 190
 191
 192 /* Return the main source file of the macro table TABLE.  */
 193 struct macro_source_file *macro_main (struct macro_table *table);
 194
 195 /* Mark the macro table TABLE so that macros defined in this table can
 196    be redefined without error.  Note that it invalid to call this if
 197    TABLE is allocated on an obstack.  */
 198 void macro_allow_redefinitions (struct macro_table *table);
 199
 200
 201 /* Record a #inclusion.
 202    Record in SOURCE's macro table that, at line number LINE in SOURCE,
 203    we #included the file INCLUDED.  Return a source file structure we
 204    can use for symbols #defined or files #included into that.  If we've
 205    already created a source file structure for this #inclusion, return
 206    the same structure we created last time.
 207
 208    The first line of the source file has a line number of 1, not 0.
 209
 210    The macro table makes its own copy of INCLUDED; the caller is
 211    responsible for freeing INCLUDED when it is no longer needed.  */
 212 struct macro_source_file *macro_include (struct macro_source_file *source,
 213                                          int line,
 214                                          const char *included);
 215
 216
 217 /* Find any source file structure for a file named NAME, either
 218    included into SOURCE, or SOURCE itself.  Return zero if we have
 219    none.  NAME is only the final portion of the filename, not the full
 220    path.  e.g., `stdio.h', not `/usr/include/stdio.h'.  If NAME
 221    appears more than once in the inclusion tree, return the
 222    least-nested inclusion --- the one closest to the main source file.  */
 223 struct macro_source_file *(macro_lookup_inclusion
 224                            (struct macro_source_file *source,
 225                             const char *name));
 226
 227
 228 /* Record an object-like #definition (i.e., one with no parameter list).
 229    Record in SOURCE's macro table that, at line number LINE in SOURCE,
 230    we #defined a preprocessor symbol named NAME, whose replacement
 231    string is REPLACEMENT.  This function makes copies of NAME and
 232    REPLACEMENT; the caller is responsible for freeing them.  */
 233 void macro_define_object (struct macro_source_file *source, int line,
 234                           const char *name, const char *replacement);
 235
 236
 237 /* Record an function-like #definition (i.e., one with a parameter list).
 238
 239    Record in SOURCE's macro table that, at line number LINE in SOURCE,
 240    we #defined a preprocessor symbol named NAME, with ARGC arguments
 241    whose names are given in ARGV, whose replacement string is REPLACEMENT.  If
 242    the macro takes a variable number of arguments, then ARGC should be
 243    one greater than the number of named arguments, and ARGV[ARGC-1]
 244    should be the string "...".  This function makes its own copies of
 245    NAME, ARGV, and REPLACEMENT; the caller is responsible for freeing
 246    them.  */
 247 void macro_define_function (struct macro_source_file *source, int line,
 248                             const char *name, int argc, const char **argv,
 249                             const char *replacement);
 250
 251
 252 /* Record an #undefinition.
 253    Record in SOURCE's macro table that, at line number LINE in SOURCE,
 254    we removed the definition for the preprocessor symbol named NAME.  */
 255 void macro_undef (struct macro_source_file *source, int line,
 256                   const char *name);
 257
 258 /* Different kinds of macro definitions.  */
 259 enum macro_kind
 260 {
 261   macro_object_like,
 262   macro_function_like
 263 };
 264
 265
 266 /* A preprocessor symbol definition.  */
 267 struct macro_definition
 268 {
 269   /* The table this definition lives in.  */
 270   struct macro_table *table;
 271
 272   /* What kind of macro it is.  */
 273   ENUM_BITFIELD (macro_kind) kind : 1;
 274
 275   /* If `kind' is `macro_function_like', the number of arguments it
 276      takes, and their names.  The names, and the array of pointers to
 277      them, are in the table's bcache, if it has one.  */
 278   int argc : 31;
 279   const char * const *argv;
 280
 281   /* The replacement string (body) of the macro.  This is in the
 282      table's bcache, if it has one.  */
 283   const char *replacement;
 284 };
 285
 286
 287 /* Return a pointer to the macro definition for NAME in scope at line
 288    number LINE of SOURCE.  If LINE is -1, return the definition in
 289    effect at the end of the file.  The macro table owns the structure;
 290    the caller need not free it.  Return zero if NAME is not #defined
 291    at that point.  */
 292 struct macro_definition *(macro_lookup_definition
 293                           (struct macro_source_file *source,
 294                            int line, const char *name));
 295
 296
 297 /* Return the source location of the definition for NAME in scope at
 298    line number LINE of SOURCE.  Set *DEFINITION_LINE to the line
 299    number of the definition, and return a source file structure for
 300    the file.  Return zero if NAME has no definition in scope at that
 301    point, and leave *DEFINITION_LINE unchanged.  */
 302 struct macro_source_file *(macro_definition_location
 303                            (struct macro_source_file *source,
 304                             int line,
 305                             const char *name,
 306                             int *definition_line));
 307
 308 /* Callback function when walking a macro table.  NAME is the name of
 309    the macro, and DEFINITION is the definition.  SOURCE is the file at the
 310    start of the include path, and LINE is the line number of the SOURCE file
 311    where the macro was defined.  USER_DATA is an arbitrary pointer which is
 312    passed by the caller to macro_for_each or macro_for_each_in_scope.  */
 313 typedef void (*macro_callback_fn) (const char *name,
 314                                    const struct macro_definition *definition,
 315                                    struct macro_source_file *source,
 316                                    int line,
 317                                    void *user_data);
 318
 319 /* Call the function FN for each macro in the macro table TABLE.
 320    USER_DATA is passed, untranslated, to FN.  */
 321 void macro_for_each (struct macro_table *table, macro_callback_fn fn,
 322                      void *user_data);
 323
 324 /* Call the function FN for each macro that is visible in a given
 325    scope.  The scope is represented by FILE and LINE.  USER_DATA is
 326    passed, untranslated, to FN.  */
 327 void macro_for_each_in_scope (struct macro_source_file *file, int line,
 328                               macro_callback_fn fn,
 329                               void *user_data);
 330
 331
 332 #endif /* MACROTAB_H */