gdb/macrotab.h

   1 /* Interface to C preprocessor macro tables for GDB.
   2    Copyright (C) 2002, 2007, 2008 Free Software Foundation, Inc.
   3    Contributed by Red Hat, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program 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 of the License, or
  10    (at your option) any later version.
  11
  12    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef MACROTAB_H
  21 #define MACROTAB_H
  22
  23 struct obstack;
  24 struct bcache;
  25
  26 /* How do we represent a source location?  I mean, how should we
  27    represent them within GDB; the user wants to use all sorts of
  28    ambiguous abbreviations, like "break 32" and "break foo.c:32"
  29    ("foo.c" may have been #included into several compilation units),
  30    but what do we disambiguate those things to?
  31
  32    - Answer 1: "Filename and line number."  (Or column number, if
  33    you're picky.)  That's not quite good enough.  For example, the
  34    same source file can be #included into several different
  35    compilation units --- which #inclusion do you mean?
  36
  37    - Answer 2: "Compilation unit, filename, and line number."  This is
  38    a pretty good answer; GDB's `struct symtab_and_line' basically
  39    embodies this representation.  But it's still ambiguous; what if a
  40    given compilation unit #includes the same file twice --- how can I
  41    set a breakpoint on line 12 of the fifth #inclusion of "foo.c"?
  42
  43    - Answer 3: "Compilation unit, chain of #inclusions, and line
  44    number."  This is analogous to the way GCC reports errors in
  45    #include files:
  46
  47         $ gcc -c base.c
  48         In file included from header2.h:8,
  49                          from header1.h:3,
  50                          from base.c:5:
  51         header3.h:1: parse error before ')' token
  52         $
  53
  54    GCC tells you exactly what path of #inclusions led you to the
  55    problem.  It gives you complete information, in a way that the
  56    following would not:
  57
  58         $ gcc -c base.c
  59         header3.h:1: parse error before ')' token
  60         $
  61
  62    Converting all of GDB to use this is a big task, and I'm not really
  63    suggesting it should be a priority.  But this module's whole
  64    purpose is to maintain structures describing the macro expansion
  65    process, so I think it's appropriate for us to take a little care
  66    to do that in a complete fashion.
  67
  68    In this interface, the first line of a file is numbered 1, not 0.
  69    This is the same convention the rest of GDB uses.  */
  70
  71
  72 /* A table of all the macro definitions for a given compilation unit.  */
  73 struct macro_table;
  74
  75 /* The definition of a single macro.  */
  76 struct macro_definition;
  77
  78 /* A source file that participated in a compilation unit --- either a
  79    main file, or an #included file.  If a file is #included more than
  80    once, the presence of the `included_from' and `included_at_line'
  81    members means that we need to make one instance of this structure
  82    for each #inclusion.  Taken as a group, these structures form a
  83    tree mapping the #inclusions that contributed to the compilation
  84    unit, with the main source file as its root.
  85
  86    Beware --- not every source file mentioned in a compilation unit's
  87    symtab structures will appear in the #inclusion tree!  As of Oct
  88    2002, GCC does record the effect of #line directives in the source
  89    line info, but not in macro info.  This means that GDB's symtabs
  90    (built from the former, among other things) may mention filenames
  91    that the #inclusion tree (built from the latter) doesn't have any
  92    record of.  See macroscope.c:sal_macro_scope for how to accomodate
  93    this.
  94
  95    It's worth noting that libcpp has a simpler way of representing all
  96    this, which we should consider switching to.  It might even be
  97    suitable for ordinary non-macro line number info.
  98
  99    Suppose you take your main source file, and after each line
 100    containing an #include directive you insert the text of the
 101    #included file.  The result is a big file that pretty much
 102    corresponds to the full text the compiler's going to see.  There's
 103    a one-to-one correspondence between lines in the big file and
 104    per-inclusion lines in the source files.  (Obviously, #include
 105    directives that are #if'd out don't count.  And you'll need to
 106    append a newline to any file that doesn't end in one, to avoid
 107    splicing the last #included line with the next line of the
 108    #including file.)
 109
 110    Libcpp calls line numbers in this big imaginary file "logical line
 111    numbers", and has a data structure called a "line map" that can map
 112    logical line numbers onto actual source filenames and line numbers,
 113    and also tell you the chain of #inclusions responsible for any
 114    particular logical line number.  Basically, this means you can pass
 115    around a single line number and some kind of "compilation unit"
 116    object and you get nice, unambiguous source code locations that
 117    distinguish between multiple #inclusions of the same file, etc.
 118
 119    Pretty neat, huh?  */
 120
 121 struct macro_source_file
 122 {
 123
 124   /* The macro table for the compilation unit this source location is
 125      a part of.  */
 126   struct macro_table *table;
 127
 128   /* A source file --- possibly a header file.  */
 129   const char *filename;
 130
 131   /* The location we were #included from, or zero if we are the
 132      compilation unit's main source file.  */
 133   struct macro_source_file *included_by;
 134
 135   /* If `included_from' is non-zero, the line number in that source
 136      file at which we were included.  */
 137   int included_at_line;
 138
 139   /* Head of a linked list of the source files #included by this file;
 140      our children in the #inclusion tree.  This list is sorted by its
 141      elements' `included_at_line' values, which are unique.  (The
 142      macro splay tree's ordering function needs this property.)  */
 143   struct macro_source_file *includes;
 144
 145   /* The next file #included by our `included_from' file; our sibling
 146      in the #inclusion tree.  */
 147   struct macro_source_file *next_included;
 148 };
 149
 150
 151 /* Create a new, empty macro table.  Allocate it in OBSTACK, or use
 152    xmalloc if OBSTACK is zero.  Use BCACHE to store all macro names,
 153    arguments, definitions, and anything else that might be the same
 154    amongst compilation units in an executable file; if BCACHE is zero,
 155    don't cache these things.
 156
 157    Note that, if either OBSTACK or BCACHE are non-zero, then removing
 158    information from the table may leak memory.  Neither obstacks nor
 159    bcaches really allow you to remove information, so although we can
 160    update the data structure to record the change, we can't free the
 161    old data.  At the moment, since we only provide obstacks and
 162    bcaches for macro tables for symtabs, this isn't a problem; only
 163    odd debugging information makes a definition and then deletes it at
 164    the same source location (although 'gcc -DFOO -UFOO -DFOO=2' does
 165    do that in GCC 4.1.2.).  */
 166 struct macro_table *new_macro_table (struct obstack *obstack,
 167                                      struct bcache *bcache);
 168
 169
 170 /* Free TABLE, and any macro definitions, source file structures,
 171    etc. it owns.  This will raise an internal error if TABLE was
 172    allocated on an obstack, or if it uses a bcache.  */
 173 void free_macro_table (struct macro_table *table);
 174
 175
 176 /* Set FILENAME as the main source file of TABLE.  Return a source
 177    file structure describing that file; if we record the #definition
 178    of macros, or the #inclusion of other files into FILENAME, we'll
 179    use that source file structure to indicate the context.
 180
 181    The "main source file" is the one that was given to the compiler;
 182    all other source files that contributed to the compilation unit are
 183    #included, directly or indirectly, from this one.
 184
 185    The macro table makes its own copy of FILENAME; the caller is
 186    responsible for freeing FILENAME when it is no longer needed.  */
 187 struct macro_source_file *macro_set_main (struct macro_table *table,
 188                                           const char *filename);
 189
 190
 191 /* Return the main source file of the macro table TABLE.  */
 192 struct macro_source_file *macro_main (struct macro_table *table);
 193
 194 /* Mark the macro table TABLE so that macros defined in this table can
 195    be redefined without error.  Note that it invalid to call this if
 196    TABLE is allocated on an obstack.  */
 197 void macro_allow_redefinitions (struct macro_table *table);
 198
 199
 200 /* Record a #inclusion.
 201    Record in SOURCE's macro table that, at line number LINE in SOURCE,
 202    we #included the file INCLUDED.  Return a source file structure we
 203    can use for symbols #defined or files #included into that.  If we've
 204    already created a source file structure for this #inclusion, return
 205    the same structure we created last time.
 206
 207    The first line of the source file has a line number of 1, not 0.
 208
 209    The macro table makes its own copy of INCLUDED; the caller is
 210    responsible for freeing INCLUDED when it is no longer needed.  */
 211 struct macro_source_file *macro_include (struct macro_source_file *source,
 212                                          int line,
 213                                          const char *included);
 214
 215
 216 /* Find any source file structure for a file named NAME, either
 217    included into SOURCE, or SOURCE itself.  Return zero if we have
 218    none.  NAME is only the final portion of the filename, not the full
 219    path.  e.g., `stdio.h', not `/usr/include/stdio.h'.  If NAME
 220    appears more than once in the inclusion tree, return the
 221    least-nested inclusion --- the one closest to the main source file.  */
 222 struct macro_source_file *(macro_lookup_inclusion
 223                            (struct macro_source_file *source,
 224                             const char *name));
 225
 226
 227 /* Record an object-like #definition (i.e., one with no parameter list).
 228    Record in SOURCE's macro table that, at line number LINE in SOURCE,
 229    we #defined a preprocessor symbol named NAME, whose replacement
 230    string is REPLACEMENT.  This function makes copies of NAME and
 231    REPLACEMENT; the caller is responsible for freeing them.  */
 232 void macro_define_object (struct macro_source_file *source, int line,
 233                           const char *name, const char *replacement);
 234
 235
 236 /* Record an function-like #definition (i.e., one with a parameter list).
 237
 238    Record in SOURCE's macro table that, at line number LINE in SOURCE,
 239    we #defined a preprocessor symbol named NAME, with ARGC arguments
 240    whose names are given in ARGV, whose replacement string is REPLACEMENT.  If
 241    the macro takes a variable number of arguments, then ARGC should be
 242    one greater than the number of named arguments, and ARGV[ARGC-1]
 243    should be the string "...".  This function makes its own copies of
 244    NAME, ARGV, and REPLACEMENT; the caller is responsible for freeing
 245    them.  */
 246 void macro_define_function (struct macro_source_file *source, int line,
 247                             const char *name, int argc, const char **argv,
 248                             const char *replacement);
 249
 250
 251 /* Record an #undefinition.
 252    Record in SOURCE's macro table that, at line number LINE in SOURCE,
 253    we removed the definition for the preprocessor symbol named NAME.  */
 254 void macro_undef (struct macro_source_file *source, int line,
 255                   const char *name);
 256
 257 /* Different kinds of macro definitions.  */
 258 enum macro_kind
 259 {
 260   macro_object_like,
 261   macro_function_like
 262 };
 263
 264
 265 /* A preprocessor symbol definition.  */
 266 struct macro_definition
 267 {
 268   /* The table this definition lives in.  */
 269   struct macro_table *table;
 270
 271   /* What kind of macro it is.  */
 272   enum macro_kind kind;
 273
 274   /* If `kind' is `macro_function_like', the number of arguments it
 275      takes, and their names.  The names, and the array of pointers to
 276      them, are in the table's bcache, if it has one.  */
 277   int argc;
 278   const char * const *argv;
 279
 280   /* The replacement string (body) of the macro.  This is in the
 281      table's bcache, if it has one.  */
 282   const char *replacement;
 283 };
 284
 285
 286 /* Return a pointer to the macro definition for NAME in scope at line
 287    number LINE of SOURCE.  If LINE is -1, return the definition in
 288    effect at the end of the file.  The macro table owns the structure;
 289    the caller need not free it.  Return zero if NAME is not #defined
 290    at that point.  */
 291 struct macro_definition *(macro_lookup_definition
 292                           (struct macro_source_file *source,
 293                            int line, const char *name));
 294
 295
 296 /* Return the source location of the definition for NAME in scope at
 297    line number LINE of SOURCE.  Set *DEFINITION_LINE to the line
 298    number of the definition, and return a source file structure for
 299    the file.  Return zero if NAME has no definition in scope at that
 300    point, and leave *DEFINITION_LINE unchanged.  */
 301 struct macro_source_file *(macro_definition_location
 302                            (struct macro_source_file *source,
 303                             int line,
 304                             const char *name,
 305                             int *definition_line));
 306
 307 /* Callback function when walking a macro table.  NAME is the name of
 308    the macro, and DEFINITION is the definition.  */
 309 typedef void (*macro_callback_fn) (const char *name,
 310                                    const struct macro_definition *definition);
 311
 312 /* Call the function FN for each macro in the macro table TABLE.  */
 313 void macro_for_each (struct macro_table *table, macro_callback_fn fn);
 314
 315
 316 #endif /* MACROTAB_H */