gcc/gcov-io.h

   1 /* File format for coverage information
   2    Copyright (C) 1996, 1997, 1998, 2000, 2002,
   3    2003, 2004, 2005, 2008, 2009 Free Software Foundation, Inc.
   4    Contributed by Bob Manson <manson@cygnus.com>.
   5    Completely remangled by Nathan Sidwell <nathan@codesourcery.com>.
   6
   7 This file is part of GCC.
   8
   9 GCC is free software; you can redistribute it and/or modify it under
  10 the terms of the GNU General Public License as published by the Free
  11 Software Foundation; either version 3, or (at your option) any later
  12 version.
  13
  14 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  15 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  16 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  17 for more details.
  18
  19 Under Section 7 of GPL version 3, you are granted additional
  20 permissions described in the GCC Runtime Library Exception, version
  21 3.1, as published by the Free Software Foundation.
  22
  23 You should have received a copy of the GNU General Public License and
  24 a copy of the GCC Runtime Library Exception along with this program;
  25 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  26 <http://www.gnu.org/licenses/>.  */
  27
  28
  29 /* Coverage information is held in two files.  A notes file, which is
  30    generated by the compiler, and a data file, which is generated by
  31    the program under test.  Both files use a similar structure.  We do
  32    not attempt to make these files backwards compatible with previous
  33    versions, as you only need coverage information when developing a
  34    program.  We do hold version information, so that mismatches can be
  35    detected, and we use a format that allows tools to skip information
  36    they do not understand or are not interested in.
  37
  38    Numbers are recorded in the 32 bit unsigned binary form of the
  39    endianness of the machine generating the file. 64 bit numbers are
  40    stored as two 32 bit numbers, the low part first.  Strings are
  41    padded with 1 to 4 NUL bytes, to bring the length up to a multiple
  42    of 4. The number of 4 bytes is stored, followed by the padded
  43    string. Zero length and NULL strings are simply stored as a length
  44    of zero (they have no trailing NUL or padding).
  45
  46         int32:  byte3 byte2 byte1 byte0 | byte0 byte1 byte2 byte3
  47         int64:  int32:low int32:high
  48         string: int32:0 | int32:length char* char:0 padding
  49         padding: | char:0 | char:0 char:0 | char:0 char:0 char:0
  50         item: int32 | int64 | string
  51
  52    The basic format of the files is
  53
  54         file : int32:magic int32:version int32:stamp record*
  55
  56    The magic ident is different for the notes and the data files.  The
  57    magic ident is used to determine the endianness of the file, when
  58    reading.  The version is the same for both files and is derived
  59    from gcc's version number. The stamp value is used to synchronize
  60    note and data files and to synchronize merging within a data
  61    file. It need not be an absolute time stamp, merely a ticker that
  62    increments fast enough and cycles slow enough to distinguish
  63    different compile/run/compile cycles.
  64
  65    Although the ident and version are formally 32 bit numbers, they
  66    are derived from 4 character ASCII strings.  The version number
  67    consists of the single character major version number, a two
  68    character minor version number (leading zero for versions less than
  69    10), and a single character indicating the status of the release.
  70    That will be 'e' experimental, 'p' prerelease and 'r' for release.
  71    Because, by good fortune, these are in alphabetical order, string
  72    collating can be used to compare version strings.  Be aware that
  73    the 'e' designation will (naturally) be unstable and might be
  74    incompatible with itself.  For gcc 3.4 experimental, it would be
  75    '304e' (0x33303465).  When the major version reaches 10, the
  76    letters A-Z will be used.  Assuming minor increments releases every
  77    6 months, we have to make a major increment every 50 years.
  78    Assuming major increments releases every 5 years, we're ok for the
  79    next 155 years -- good enough for me.
  80
  81    A record has a tag, length and variable amount of data.
  82
  83         record: header data
  84         header: int32:tag int32:length
  85         data: item*
  86
  87    Records are not nested, but there is a record hierarchy.  Tag
  88    numbers reflect this hierarchy.  Tags are unique across note and
  89    data files.  Some record types have a varying amount of data.  The
  90    LENGTH is the number of 4bytes that follow and is usually used to
  91    determine how much data.  The tag value is split into 4 8-bit
  92    fields, one for each of four possible levels.  The most significant
  93    is allocated first.  Unused levels are zero.  Active levels are
  94    odd-valued, so that the LSB of the level is one.  A sub-level
  95    incorporates the values of its superlevels.  This formatting allows
  96    you to determine the tag hierarchy, without understanding the tags
  97    themselves, and is similar to the standard section numbering used
  98    in technical documents.  Level values [1..3f] are used for common
  99    tags, values [41..9f] for the notes file and [a1..ff] for the data
 100    file.
 101
 102    The basic block graph file contains the following records
 103         note: unit function-graph*
 104         unit: header int32:checksum string:source
 105         function-graph: announce_function basic_blocks {arcs | lines}*
 106         announce_function: header int32:ident
 107                 int32:lineno_checksum int32:cfg_checksum
 108                 string:name string:source int32:lineno
 109         basic_block: header int32:flags*
 110         arcs: header int32:block_no arc*
 111         arc:  int32:dest_block int32:flags
 112         lines: header int32:block_no line*
 113                int32:0 string:NULL
 114         line:  int32:line_no | int32:0 string:filename
 115
 116    The BASIC_BLOCK record holds per-bb flags.  The number of blocks
 117    can be inferred from its data length.  There is one ARCS record per
 118    basic block.  The number of arcs from a bb is implicit from the
 119    data length.  It enumerates the destination bb and per-arc flags.
 120    There is one LINES record per basic block, it enumerates the source
 121    lines which belong to that basic block.  Source file names are
 122    introduced by a line number of 0, following lines are from the new
 123    source file.  The initial source file for the function is NULL, but
 124    the current source file should be remembered from one LINES record
 125    to the next.  The end of a block is indicated by an empty filename
 126    - this does not reset the current source file.  Note there is no
 127    ordering of the ARCS and LINES records: they may be in any order,
 128    interleaved in any manner.  The current filename follows the order
 129    the LINES records are stored in the file, *not* the ordering of the
 130    blocks they are for.
 131
 132    The data file contains the following records.
 133         data: {unit function-data* summary:object summary:program*}*
 134         unit: header int32:checksum
 135         function-data:  announce_function arc_counts
 136         announce_function: header int32:ident
 137                 int32:lineno_checksum int32:cfg_checksum
 138         arc_counts: header int64:count*
 139         summary: int32:checksum {count-summary}GCOV_COUNTERS
 140         count-summary:  int32:num int32:runs int64:sum
 141                         int64:max int64:sum_max
 142
 143    The ANNOUNCE_FUNCTION record is the same as that in the note file,
 144    but without the source location.  The ARC_COUNTS gives the counter
 145    values for those arcs that are instrumented.  The SUMMARY records
 146    give information about the whole object file and about the whole
 147    program.  The checksum is used for whole program summaries, and
 148    disambiguates different programs which include the same
 149    instrumented object file.  There may be several program summaries,
 150    each with a unique checksum.  The object summary's checksum is zero.
 151    Note that the data file might contain information from several runs
 152    concatenated, or the data might be merged.
 153
 154    This file is included by both the compiler, gcov tools and the
 155    runtime support library libgcov. IN_LIBGCOV and IN_GCOV are used to
 156    distinguish which case is which.  If IN_LIBGCOV is nonzero,
 157    libgcov is being built. If IN_GCOV is nonzero, the gcov tools are
 158    being built. Otherwise the compiler is being built. IN_GCOV may be
 159    positive or negative. If positive, we are compiling a tool that
 160    requires additional functions (see the code for knowledge of what
 161    those functions are).  */
 162
 163 #ifndef GCC_GCOV_IO_H
 164 #define GCC_GCOV_IO_H
 165
 166 #if IN_LIBGCOV
 167 /* About the target */
 168
 169 #if BITS_PER_UNIT == 8
 170 typedef unsigned gcov_unsigned_t __attribute__ ((mode (SI)));
 171 typedef unsigned gcov_position_t __attribute__ ((mode (SI)));
 172 #if LONG_LONG_TYPE_SIZE > 32
 173 typedef signed gcov_type __attribute__ ((mode (DI)));
 174 #else
 175 typedef signed gcov_type __attribute__ ((mode (SI)));
 176 #endif
 177 #else
 178 #if BITS_PER_UNIT == 16
 179 typedef unsigned gcov_unsigned_t __attribute__ ((mode (HI)));
 180 typedef unsigned gcov_position_t __attribute__ ((mode (HI)));
 181 #if LONG_LONG_TYPE_SIZE > 32
 182 typedef signed gcov_type __attribute__ ((mode (SI)));
 183 #else
 184 typedef signed gcov_type __attribute__ ((mode (HI)));
 185 #endif
 186 #else
 187 typedef unsigned gcov_unsigned_t __attribute__ ((mode (QI)));
 188 typedef unsigned gcov_position_t __attribute__ ((mode (QI)));
 189 #if LONG_LONG_TYPE_SIZE > 32
 190 typedef signed gcov_type __attribute__ ((mode (HI)));
 191 #else
 192 typedef signed gcov_type __attribute__ ((mode (QI)));
 193 #endif
 194 #endif
 195 #endif
 196
 197
 198 #if defined (TARGET_POSIX_IO)
 199 #define GCOV_LOCKED 1
 200 #else
 201 #define GCOV_LOCKED 0
 202 #endif
 203
 204 #else /* !IN_LIBGCOV */
 205 /* About the host */
 206
 207 typedef unsigned gcov_unsigned_t;
 208 typedef unsigned gcov_position_t;
 209 /* gcov_type is typedef'd elsewhere for the compiler */
 210 #if IN_GCOV
 211 #define GCOV_LINKAGE static
 212 typedef HOST_WIDEST_INT gcov_type;
 213 #if IN_GCOV > 0
 214 #include <sys/types.h>
 215 #endif
 216 #else /*!IN_GCOV */
 217 #define GCOV_TYPE_SIZE (LONG_LONG_TYPE_SIZE > 32 ? 64 : 32)
 218 #endif
 219
 220 #if defined (HOST_HAS_F_SETLKW)
 221 #define GCOV_LOCKED 1
 222 #else
 223 #define GCOV_LOCKED 0
 224 #endif
 225
 226 #endif /* !IN_LIBGCOV */
 227
 228 /* In gcov we want function linkage to be static.  In the compiler we want
 229    it extern, so that they can be accessed from elsewhere.  In libgcov we
 230    need these functions to be extern, so prefix them with __gcov.  In
 231    libgcov they must also be hidden so that the instance in the executable
 232    is not also used in a DSO.  */
 233 #if IN_LIBGCOV
 234
 235 #include "tconfig.h"
 236
 237 #define gcov_var __gcov_var
 238 #define gcov_open __gcov_open
 239 #define gcov_close __gcov_close
 240 #define gcov_write_tag_length __gcov_write_tag_length
 241 #define gcov_position __gcov_position
 242 #define gcov_seek __gcov_seek
 243 #define gcov_rewrite __gcov_rewrite
 244 #define gcov_is_error __gcov_is_error
 245 #define gcov_write_unsigned __gcov_write_unsigned
 246 #define gcov_write_counter __gcov_write_counter
 247 #define gcov_write_summary __gcov_write_summary
 248 #define gcov_read_unsigned __gcov_read_unsigned
 249 #define gcov_read_counter __gcov_read_counter
 250 #define gcov_read_summary __gcov_read_summary
 251
 252 /* Poison these, so they don't accidentally slip in.  */
 253 #pragma GCC poison gcov_write_string gcov_write_tag gcov_write_length
 254 #pragma GCC poison gcov_read_string gcov_sync gcov_time gcov_magic
 255
 256 #ifdef HAVE_GAS_HIDDEN
 257 #define ATTRIBUTE_HIDDEN  __attribute__ ((__visibility__ ("hidden")))
 258 #else
 259 #define ATTRIBUTE_HIDDEN
 260 #endif
 261
 262 #else
 263
 264 #define ATTRIBUTE_HIDDEN
 265
 266 #endif
 267
 268 #ifndef GCOV_LINKAGE
 269 #define GCOV_LINKAGE extern
 270 #endif
 271
 272 /* File suffixes.  */
 273 #define GCOV_DATA_SUFFIX ".gcda"
 274 #define GCOV_NOTE_SUFFIX ".gcno"
 275
 276 /* File magic. Must not be palindromes.  */
 277 #define GCOV_DATA_MAGIC ((gcov_unsigned_t)0x67636461) /* "gcda" */
 278 #define GCOV_NOTE_MAGIC ((gcov_unsigned_t)0x67636e6f) /* "gcno" */
 279
 280 /* gcov-iov.h is automatically generated by the makefile from
 281    version.c, it looks like
 282         #define GCOV_VERSION ((gcov_unsigned_t)0x89abcdef)
 283 */
 284 #include "gcov-iov.h"
 285
 286 /* Convert a magic or version number to a 4 character string.  */
 287 #define GCOV_UNSIGNED2STRING(ARRAY,VALUE)       \
 288   ((ARRAY)[0] = (char)((VALUE) >> 24),          \
 289    (ARRAY)[1] = (char)((VALUE) >> 16),          \
 290    (ARRAY)[2] = (char)((VALUE) >> 8),           \
 291    (ARRAY)[3] = (char)((VALUE) >> 0))
 292
 293 /* The record tags.  Values [1..3f] are for tags which may be in either
 294    file.  Values [41..9f] for those in the note file and [a1..ff] for
 295    the data file.  The tag value zero is used as an explicit end of
 296    file marker -- it is not required to be present.  */
 297
 298 #define GCOV_TAG_FUNCTION        ((gcov_unsigned_t)0x01000000)
 299 #define GCOV_TAG_FUNCTION_LENGTH (3)
 300 #define GCOV_TAG_BLOCKS          ((gcov_unsigned_t)0x01410000)
 301 #define GCOV_TAG_BLOCKS_LENGTH(NUM) (NUM)
 302 #define GCOV_TAG_BLOCKS_NUM(LENGTH) (LENGTH)
 303 #define GCOV_TAG_ARCS            ((gcov_unsigned_t)0x01430000)
 304 #define GCOV_TAG_ARCS_LENGTH(NUM)  (1 + (NUM) * 2)
 305 #define GCOV_TAG_ARCS_NUM(LENGTH)  (((LENGTH) - 1) / 2)
 306 #define GCOV_TAG_LINES           ((gcov_unsigned_t)0x01450000)
 307 #define GCOV_TAG_COUNTER_BASE    ((gcov_unsigned_t)0x01a10000)
 308 #define GCOV_TAG_COUNTER_LENGTH(NUM) ((NUM) * 2)
 309 #define GCOV_TAG_COUNTER_NUM(LENGTH) ((LENGTH) / 2)
 310 #define GCOV_TAG_OBJECT_SUMMARY  ((gcov_unsigned_t)0xa1000000)
 311 #define GCOV_TAG_PROGRAM_SUMMARY ((gcov_unsigned_t)0xa3000000)
 312 #define GCOV_TAG_SUMMARY_LENGTH  \
 313         (1 + GCOV_COUNTERS_SUMMABLE * (2 + 3 * 2))
 314
 315 /* Counters that are collected.  */
 316 #define GCOV_COUNTER_ARCS       0  /* Arc transitions.  */
 317 #define GCOV_COUNTERS_SUMMABLE  1  /* Counters which can be
 318                                       summaried.  */
 319 #define GCOV_FIRST_VALUE_COUNTER 1 /* The first of counters used for value
 320                                       profiling.  They must form a consecutive
 321                                       interval and their order must match
 322                                       the order of HIST_TYPEs in
 323                                       value-prof.h.  */
 324 #define GCOV_COUNTER_V_INTERVAL 1  /* Histogram of value inside an interval.  */
 325 #define GCOV_COUNTER_V_POW2     2  /* Histogram of exact power2 logarithm
 326                                       of a value.  */
 327 #define GCOV_COUNTER_V_SINGLE   3  /* The most common value of expression.  */
 328 #define GCOV_COUNTER_V_DELTA    4  /* The most common difference between
 329                                       consecutive values of expression.  */
 330
 331 #define GCOV_COUNTER_V_INDIR    5  /* The most common indirect address */
 332 #define GCOV_COUNTER_AVERAGE    6  /* Compute average value passed to the
 333                                       counter.  */
 334 #define GCOV_COUNTER_IOR        7  /* IOR of the all values passed to
 335                                       counter.  */
 336 #define GCOV_LAST_VALUE_COUNTER 7  /* The last of counters used for value
 337                                       profiling.  */
 338 #define GCOV_COUNTERS           8
 339
 340 /* Number of counters used for value profiling.  */
 341 #define GCOV_N_VALUE_COUNTERS \
 342   (GCOV_LAST_VALUE_COUNTER - GCOV_FIRST_VALUE_COUNTER + 1)
 343
 344   /* A list of human readable names of the counters */
 345 #define GCOV_COUNTER_NAMES      {"arcs", "interval", "pow2", "single", \
 346                                  "delta","indirect_call", "average", "ior"}
 347
 348   /* Names of merge functions for counters.  */
 349 #define GCOV_MERGE_FUNCTIONS    {"__gcov_merge_add",    \
 350                                  "__gcov_merge_add",    \
 351                                  "__gcov_merge_add",    \
 352                                  "__gcov_merge_single", \
 353                                  "__gcov_merge_delta",  \
 354                                  "__gcov_merge_single", \
 355                                  "__gcov_merge_add",    \
 356                                  "__gcov_merge_ior"}
 357
 358 /* Convert a counter index to a tag.  */
 359 #define GCOV_TAG_FOR_COUNTER(COUNT)                             \
 360         (GCOV_TAG_COUNTER_BASE + ((gcov_unsigned_t)(COUNT) << 17))
 361 /* Convert a tag to a counter.  */
 362 #define GCOV_COUNTER_FOR_TAG(TAG)                                       \
 363         ((unsigned)(((TAG) - GCOV_TAG_COUNTER_BASE) >> 17))
 364 /* Check whether a tag is a counter tag.  */
 365 #define GCOV_TAG_IS_COUNTER(TAG)                                \
 366         (!((TAG) & 0xFFFF) && GCOV_COUNTER_FOR_TAG (TAG) < GCOV_COUNTERS)
 367
 368 /* The tag level mask has 1's in the position of the inner levels, &
 369    the lsb of the current level, and zero on the current and outer
 370    levels.  */
 371 #define GCOV_TAG_MASK(TAG) (((TAG) - 1) ^ (TAG))
 372
 373 /* Return nonzero if SUB is an immediate subtag of TAG.  */
 374 #define GCOV_TAG_IS_SUBTAG(TAG,SUB)                             \
 375         (GCOV_TAG_MASK (TAG) >> 8 == GCOV_TAG_MASK (SUB)        \
 376          && !(((SUB) ^ (TAG)) & ~GCOV_TAG_MASK(TAG)))
 377
 378 /* Return nonzero if SUB is at a sublevel to TAG.  */
 379 #define GCOV_TAG_IS_SUBLEVEL(TAG,SUB)                           \
 380         (GCOV_TAG_MASK (TAG) > GCOV_TAG_MASK (SUB))
 381
 382 /* Basic block flags.  */
 383 #define GCOV_BLOCK_UNEXPECTED   (1 << 1)
 384
 385 /* Arc flags.  */
 386 #define GCOV_ARC_ON_TREE        (1 << 0)
 387 #define GCOV_ARC_FAKE           (1 << 1)
 388 #define GCOV_ARC_FALLTHROUGH    (1 << 2)
 389
 390 /* Structured records.  */
 391
 392 /* Cumulative counter data.  */
 393 struct gcov_ctr_summary
 394 {
 395   gcov_unsigned_t num;          /* number of counters.  */
 396   gcov_unsigned_t runs;         /* number of program runs */
 397   gcov_type sum_all;            /* sum of all counters accumulated.  */
 398   gcov_type run_max;            /* maximum value on a single run.  */
 399   gcov_type sum_max;            /* sum of individual run max values.  */
 400 };
 401
 402 /* Object & program summary record.  */
 403 struct gcov_summary
 404 {
 405   gcov_unsigned_t checksum;     /* checksum of program */
 406   struct gcov_ctr_summary ctrs[GCOV_COUNTERS_SUMMABLE];
 407 };
 408
 409 /* Structures embedded in coveraged program.  The structures generated
 410    by write_profile must match these.  */
 411
 412 #if IN_LIBGCOV
 413 /* Information about a single function.  This uses the trailing array
 414    idiom. The number of counters is determined from the counter_mask
 415    in gcov_info.  We hold an array of function info, so have to
 416    explicitly calculate the correct array stride.  */
 417
 418 struct gcov_fn_info
 419 {
 420   gcov_unsigned_t ident;        /* unique ident of function */
 421   gcov_unsigned_t lineno_checksum;      /* function lineo_checksum */
 422   gcov_unsigned_t cfg_checksum; /* function cfg checksum */
 423   unsigned n_ctrs[0];           /* instrumented counters */
 424 };
 425
 426 /* Type of function used to merge counters.  */
 427 typedef void (*gcov_merge_fn) (gcov_type *, gcov_unsigned_t);
 428
 429 /* Information about counters.  */
 430 struct gcov_ctr_info
 431 {
 432   gcov_unsigned_t num;          /* number of counters.  */
 433   gcov_type *values;            /* their values.  */
 434   gcov_merge_fn merge;          /* The function used to merge them.  */
 435 };
 436
 437 /* Information about a single object file.  */
 438 struct gcov_info
 439 {
 440   gcov_unsigned_t version;      /* expected version number */
 441   struct gcov_info *next;       /* link to next, used by libgcov */
 442
 443   gcov_unsigned_t stamp;        /* uniquifying time stamp */
 444   const char *filename;         /* output file name */
 445
 446   unsigned n_functions;         /* number of functions */
 447   const struct gcov_fn_info *functions; /* table of functions */
 448
 449   unsigned ctr_mask;            /* mask of counters instrumented.  */
 450   struct gcov_ctr_info counts[0]; /* count data. The number of bits
 451                                      set in the ctr_mask field
 452                                      determines how big this array
 453                                      is.  */
 454 };
 455
 456 /* Register a new object file module.  */
 457 extern void __gcov_init (struct gcov_info *) ATTRIBUTE_HIDDEN;
 458
 459 /* Called before fork, to avoid double counting.  */
 460 extern void __gcov_flush (void) ATTRIBUTE_HIDDEN;
 461
 462 /* The merge function that just sums the counters.  */
 463 extern void __gcov_merge_add (gcov_type *, unsigned) ATTRIBUTE_HIDDEN;
 464
 465 /* The merge function to choose the most common value.  */
 466 extern void __gcov_merge_single (gcov_type *, unsigned) ATTRIBUTE_HIDDEN;
 467
 468 /* The merge function to choose the most common difference between
 469    consecutive values.  */
 470 extern void __gcov_merge_delta (gcov_type *, unsigned) ATTRIBUTE_HIDDEN;
 471
 472 /* The merge function that just ors the counters together.  */
 473 extern void __gcov_merge_ior (gcov_type *, unsigned) ATTRIBUTE_HIDDEN;
 474
 475 /* The profiler functions.  */
 476 extern void __gcov_interval_profiler (gcov_type *, gcov_type, int, unsigned);
 477 extern void __gcov_pow2_profiler (gcov_type *, gcov_type);
 478 extern void __gcov_one_value_profiler (gcov_type *, gcov_type);
 479 extern void __gcov_indirect_call_profiler (gcov_type *, gcov_type, void *, void *);
 480 extern void __gcov_average_profiler (gcov_type *, gcov_type);
 481 extern void __gcov_ior_profiler (gcov_type *, gcov_type);
 482
 483 #ifndef inhibit_libc
 484 /* The wrappers around some library functions..  */
 485 extern pid_t __gcov_fork (void) ATTRIBUTE_HIDDEN;
 486 extern int __gcov_execl (const char *, char *, ...) ATTRIBUTE_HIDDEN;
 487 extern int __gcov_execlp (const char *, char *, ...) ATTRIBUTE_HIDDEN;
 488 extern int __gcov_execle (const char *, char *, ...) ATTRIBUTE_HIDDEN;
 489 extern int __gcov_execv (const char *, char *const []) ATTRIBUTE_HIDDEN;
 490 extern int __gcov_execvp (const char *, char *const []) ATTRIBUTE_HIDDEN;
 491 extern int __gcov_execve (const char *, char  *const [], char *const [])
 492   ATTRIBUTE_HIDDEN;
 493 #endif
 494
 495 #endif /* IN_LIBGCOV */
 496
 497 #if IN_LIBGCOV >= 0
 498
 499 /* Optimum number of gcov_unsigned_t's read from or written to disk.  */
 500 #define GCOV_BLOCK_SIZE (1 << 10)
 501
 502 GCOV_LINKAGE struct gcov_var
 503 {
 504   FILE *file;
 505   gcov_position_t start;        /* Position of first byte of block */
 506   unsigned offset;              /* Read/write position within the block.  */
 507   unsigned length;              /* Read limit in the block.  */
 508   unsigned overread;            /* Number of words overread.  */
 509   int error;                    /* < 0 overflow, > 0 disk error.  */
 510   int mode;                     /* < 0 writing, > 0 reading */
 511 #if IN_LIBGCOV
 512   /* Holds one block plus 4 bytes, thus all coverage reads & writes
 513      fit within this buffer and we always can transfer GCOV_BLOCK_SIZE
 514      to and from the disk. libgcov never backtracks and only writes 4
 515      or 8 byte objects.  */
 516   gcov_unsigned_t buffer[GCOV_BLOCK_SIZE + 1];
 517 #else
 518   int endian;                   /* Swap endianness.  */
 519   /* Holds a variable length block, as the compiler can write
 520      strings and needs to backtrack.  */
 521   size_t alloc;
 522   gcov_unsigned_t *buffer;
 523 #endif
 524 } gcov_var ATTRIBUTE_HIDDEN;
 525
 526 /* Functions for reading and writing gcov files. In libgcov you can
 527    open the file for reading then writing. Elsewhere you can open the
 528    file either for reading or for writing. When reading a file you may
 529    use the gcov_read_* functions, gcov_sync, gcov_position, &
 530    gcov_error. When writing a file you may use the gcov_write
 531    functions, gcov_seek & gcov_error. When a file is to be rewritten
 532    you use the functions for reading, then gcov_rewrite then the
 533    functions for writing.  Your file may become corrupted if you break
 534    these invariants.  */
 535 #if IN_LIBGCOV
 536 GCOV_LINKAGE int gcov_open (const char */*name*/) ATTRIBUTE_HIDDEN;
 537 #else
 538 GCOV_LINKAGE int gcov_open (const char */*name*/, int /*direction*/);
 539 GCOV_LINKAGE int gcov_magic (gcov_unsigned_t, gcov_unsigned_t);
 540 #endif
 541 GCOV_LINKAGE int gcov_close (void) ATTRIBUTE_HIDDEN;
 542
 543 /* Available everywhere.  */
 544 static gcov_position_t gcov_position (void);
 545 static int gcov_is_error (void);
 546
 547 GCOV_LINKAGE gcov_unsigned_t gcov_read_unsigned (void) ATTRIBUTE_HIDDEN;
 548 GCOV_LINKAGE gcov_type gcov_read_counter (void) ATTRIBUTE_HIDDEN;
 549 GCOV_LINKAGE void gcov_read_summary (struct gcov_summary *) ATTRIBUTE_HIDDEN;
 550
 551 #if IN_LIBGCOV
 552 /* Available only in libgcov */
 553 GCOV_LINKAGE void gcov_write_counter (gcov_type) ATTRIBUTE_HIDDEN;
 554 GCOV_LINKAGE void gcov_write_tag_length (gcov_unsigned_t, gcov_unsigned_t)
 555     ATTRIBUTE_HIDDEN;
 556 GCOV_LINKAGE void gcov_write_summary (gcov_unsigned_t /*tag*/,
 557                                       const struct gcov_summary *)
 558     ATTRIBUTE_HIDDEN;
 559 static void gcov_rewrite (void);
 560 GCOV_LINKAGE void gcov_seek (gcov_position_t /*position*/) ATTRIBUTE_HIDDEN;
 561 #else
 562 /* Available outside libgcov */
 563 GCOV_LINKAGE const char *gcov_read_string (void);
 564 GCOV_LINKAGE void gcov_sync (gcov_position_t /*base*/,
 565                              gcov_unsigned_t /*length */);
 566 #endif
 567
 568 #if !IN_GCOV
 569 /* Available outside gcov */
 570 GCOV_LINKAGE void gcov_write_unsigned (gcov_unsigned_t) ATTRIBUTE_HIDDEN;
 571 #endif
 572
 573 #if !IN_GCOV && !IN_LIBGCOV
 574 /* Available only in compiler */
 575 GCOV_LINKAGE void gcov_write_string (const char *);
 576 GCOV_LINKAGE gcov_position_t gcov_write_tag (gcov_unsigned_t);
 577 GCOV_LINKAGE void gcov_write_length (gcov_position_t /*position*/);
 578 #endif
 579
 580 #if IN_GCOV > 0
 581 /* Available in gcov */
 582 GCOV_LINKAGE time_t gcov_time (void);
 583 #endif
 584
 585 /* Save the current position in the gcov file.  */
 586
 587 static inline gcov_position_t
 588 gcov_position (void)
 589 {
 590   gcc_assert (gcov_var.mode > 0);
 591   return gcov_var.start + gcov_var.offset;
 592 }
 593
 594 /* Return nonzero if the error flag is set.  */
 595
 596 static inline int
 597 gcov_is_error (void)
 598 {
 599   return gcov_var.file ? gcov_var.error : 1;
 600 }
 601
 602 #if IN_LIBGCOV
 603 /* Move to beginning of file and initialize for writing.  */
 604
 605 static inline void
 606 gcov_rewrite (void)
 607 {
 608   gcc_assert (gcov_var.mode > 0);
 609   gcov_var.mode = -1;
 610   gcov_var.start = 0;
 611   gcov_var.offset = 0;
 612   fseek (gcov_var.file, 0L, SEEK_SET);
 613 }
 614 #endif
 615
 616 #endif /* IN_LIBGCOV >= 0 */
 617
 618 #endif /* GCC_GCOV_IO_H */