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1/*===- GCDAProfiling.c - Support library for GCDA file emission -----------===*\2|*3|* Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4|* See https://llvm.org/LICENSE.txt for license information.5|* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6|*7|*===----------------------------------------------------------------------===*|8|*9|* This file implements the call back routines for the gcov profiling10|* instrumentation pass. Link against this library when running code through11|* the -insert-gcov-profiling LLVM pass.12|*13|* We emit files in a corrupt version of GCOV's "gcda" file format. These files14|* are only close enough that LCOV will happily parse them. Anything that lcov15|* ignores is missing.16|*17|* TODO: gcov is multi-process safe by having each exit open the existing file18|* and append to it. We'd like to achieve that and be thread-safe too.19|*20\*===----------------------------------------------------------------------===*/21 22#if !defined(__Fuchsia__)23 24#if defined(__linux__)25// For fdopen()26#define _DEFAULT_SOURCE27#endif28 29#include <errno.h>30#include <fcntl.h>31#include <stdint.h>32#include <stdio.h>33#include <stdlib.h>34#include <string.h>35 36#if defined(_WIN32)37#define WIN32_LEAN_AND_MEAN38#include <windows.h>39#include "WindowsMMap.h"40#else41#include <sys/file.h>42#include <sys/mman.h>43#include <sys/types.h>44#include <unistd.h>45#endif46 47#include "InstrProfiling.h"48#include "InstrProfilingUtil.h"49 50/* #define DEBUG_GCDAPROFILING */51 52enum {53 GCOV_DATA_MAGIC = 0x67636461, // "gcda"54 55 GCOV_TAG_FUNCTION = 0x01000000,56 GCOV_TAG_COUNTER_ARCS = 0x01a10000,57 // GCOV_TAG_OBJECT_SUMMARY superseded GCOV_TAG_PROGRAM_SUMMARY in GCC 9.58 GCOV_TAG_OBJECT_SUMMARY = 0xa1000000,59 GCOV_TAG_PROGRAM_SUMMARY = 0xa3000000,60};61 62/*63 * --- GCOV file format I/O primitives ---64 */65 66/*67 * The current file name we're outputting. Used primarily for error logging.68 */69static char *filename = NULL;70 71/*72 * The current file we're outputting.73 */74static FILE *output_file = NULL;75 76/*77 * Buffer that we write things into.78 */79#define WRITE_BUFFER_SIZE (128 * 1024)80static unsigned char *write_buffer = NULL;81static uint64_t cur_buffer_size = 0;82static uint64_t cur_pos = 0;83static uint64_t file_size = 0;84static int new_file = 0;85static int gcov_version;86#if defined(_WIN32)87static HANDLE mmap_handle = NULL;88#endif89static int fd = -1;90 91typedef void (*fn_ptr)(void);92 93typedef void* dynamic_object_id;94// The address of this variable identifies a given dynamic object.95static dynamic_object_id current_id;96#define CURRENT_ID (¤t_id)97 98struct fn_node {99 dynamic_object_id id;100 fn_ptr fn;101 struct fn_node* next;102};103 104struct fn_list {105 struct fn_node *head, *tail;106};107 108/*109 * A list of functions to write out the data, shared between all dynamic objects.110 */111struct fn_list writeout_fn_list;112 113/*114 * A list of reset functions, shared between all dynamic objects.115 */116struct fn_list reset_fn_list;117 118static void fn_list_insert(struct fn_list* list, fn_ptr fn) {119 struct fn_node* new_node = malloc(sizeof(struct fn_node));120 new_node->fn = fn;121 new_node->next = NULL;122 new_node->id = CURRENT_ID;123 124 if (!list->head) {125 list->head = list->tail = new_node;126 } else {127 list->tail->next = new_node;128 list->tail = new_node;129 }130}131 132static void fn_list_remove(struct fn_list* list) {133 struct fn_node* curr = list->head;134 struct fn_node* prev = NULL;135 struct fn_node* next = NULL;136 137 while (curr) {138 next = curr->next;139 140 if (curr->id == CURRENT_ID) {141 if (curr == list->head) {142 list->head = next;143 }144 145 if (curr == list->tail) {146 list->tail = prev;147 }148 149 if (prev) {150 prev->next = next;151 }152 153 free(curr);154 } else {155 prev = curr;156 }157 158 curr = next;159 }160}161 162static void resize_write_buffer(uint64_t size) {163 if (!new_file) return;164 size += cur_pos;165 if (size <= cur_buffer_size) return;166 size = (size - 1) / WRITE_BUFFER_SIZE + 1;167 size *= WRITE_BUFFER_SIZE;168 write_buffer = realloc(write_buffer, size);169 cur_buffer_size = size;170}171 172static void write_bytes(const char *s, size_t len) {173 resize_write_buffer(len);174 memcpy(&write_buffer[cur_pos], s, len);175 cur_pos += len;176}177 178static void write_32bit_value(uint32_t i) {179 write_bytes((char*)&i, 4);180}181 182static void write_64bit_value(uint64_t i) {183 // GCOV uses a lo-/hi-word format even on big-endian systems.184 // See also GCOVBuffer::readInt64 in LLVM.185 uint32_t lo = (uint32_t) i;186 uint32_t hi = (uint32_t) (i >> 32);187 write_32bit_value(lo);188 write_32bit_value(hi);189}190 191static uint32_t read_32bit_value(void) {192 uint32_t val;193 194 if (new_file)195 return (uint32_t)-1;196 197 val = *(uint32_t*)&write_buffer[cur_pos];198 cur_pos += 4;199 return val;200}201 202static uint64_t read_64bit_value(void) {203 // GCOV uses a lo-/hi-word format even on big-endian systems.204 // See also GCOVBuffer::readInt64 in LLVM.205 uint32_t lo = read_32bit_value();206 uint32_t hi = read_32bit_value();207 return ((uint64_t)hi << 32) | ((uint64_t)lo);208}209 210static char *mangle_filename(const char *orig_filename) {211 char *new_filename;212 size_t prefix_len;213 int prefix_strip;214 const char *prefix = lprofGetPathPrefix(&prefix_strip, &prefix_len);215 216 if (prefix == NULL)217 return strdup(orig_filename);218 219 new_filename = malloc(prefix_len + 1 + strlen(orig_filename) + 1);220 lprofApplyPathPrefix(new_filename, orig_filename, prefix, prefix_len,221 prefix_strip);222 223 return new_filename;224}225 226static int map_file(void) {227 fseek(output_file, 0L, SEEK_END);228 file_size = ftell(output_file);229 230 /* A size of 0 means the file has been created just now (possibly by another231 * process in lock-after-open race condition). No need to mmap. */232 if (file_size == 0)233 return -1;234 235#if defined(_WIN32)236 HANDLE mmap_fd;237 if (fd == -1)238 mmap_fd = INVALID_HANDLE_VALUE;239 else240 mmap_fd = (HANDLE)_get_osfhandle(fd);241 242 mmap_handle = CreateFileMapping(mmap_fd, NULL, PAGE_READWRITE, DWORD_HI(file_size), DWORD_LO(file_size), NULL);243 if (mmap_handle == NULL) {244 fprintf(stderr, "profiling: %s: cannot create file mapping: %lu\n",245 filename, GetLastError());246 return -1;247 }248 249 write_buffer = MapViewOfFile(mmap_handle, FILE_MAP_WRITE, 0, 0, file_size);250 if (write_buffer == NULL) {251 fprintf(stderr, "profiling: %s: cannot map: %lu\n", filename,252 GetLastError());253 CloseHandle(mmap_handle);254 return -1;255 }256#else257 write_buffer = mmap(0, file_size, PROT_READ | PROT_WRITE,258 MAP_FILE | MAP_SHARED, fd, 0);259 if (write_buffer == (void *)-1) {260 int errnum = errno;261 fprintf(stderr, "profiling: %s: cannot map: %s\n", filename,262 strerror(errnum));263 return -1;264 }265#endif266 267 return 0;268}269 270static void unmap_file(void) {271#if defined(_WIN32)272 if (!UnmapViewOfFile(write_buffer)) {273 fprintf(stderr, "profiling: %s: cannot unmap mapped view: %lu\n", filename,274 GetLastError());275 }276 277 if (!CloseHandle(mmap_handle)) {278 fprintf(stderr, "profiling: %s: cannot close file mapping handle: %lu\n",279 filename, GetLastError());280 }281 282 mmap_handle = NULL;283#else284 if (munmap(write_buffer, file_size) == -1) {285 int errnum = errno;286 fprintf(stderr, "profiling: %s: cannot munmap: %s\n", filename,287 strerror(errnum));288 }289#endif290 291 write_buffer = NULL;292 file_size = 0;293}294 295/*296 * --- LLVM line counter API ---297 */298 299/* A file in this case is a translation unit. Each .o file built with line300 * profiling enabled will emit to a different file. Only one file may be301 * started at a time.302 */303COMPILER_RT_VISIBILITY304void llvm_gcda_start_file(const char *orig_filename, uint32_t version,305 uint32_t checksum) {306 const char *mode = "r+b";307 filename = mangle_filename(orig_filename);308 309 /* Try just opening the file. */310 fd = open(filename, O_RDWR | O_BINARY);311 312 if (fd == -1) {313 /* Try creating the file. */314 fd = open(filename, O_RDWR | O_CREAT | O_EXCL | O_BINARY, 0644);315 if (fd != -1) {316 mode = "w+b";317 } else {318 /* Try creating the directories first then opening the file. */319 __llvm_profile_recursive_mkdir(filename);320 fd = open(filename, O_RDWR | O_CREAT | O_EXCL | O_BINARY, 0644);321 if (fd != -1) {322 mode = "w+b";323 } else {324 /* Another process may have created the file just now.325 * Try opening it without O_CREAT and O_EXCL. */326 fd = open(filename, O_RDWR | O_BINARY);327 if (fd == -1) {328 /* Bah! It's hopeless. */329 int errnum = errno;330 fprintf(stderr, "profiling: %s: cannot open: %s\n", filename,331 strerror(errnum));332 return;333 }334 }335 }336 }337 338 /* Try to flock the file to serialize concurrent processes writing out to the339 * same GCDA. This can fail if the filesystem doesn't support it, but in that340 * case we'll just carry on with the old racy behaviour and hope for the best.341 */342 lprofLockFd(fd);343 output_file = fdopen(fd, mode);344 345 /* Initialize the write buffer. */346 new_file = 0;347 write_buffer = NULL;348 cur_buffer_size = 0;349 cur_pos = 0;350 351 if (map_file() == -1) {352 /* The file has been created just now (file_size == 0) or mmap failed353 * unexpectedly. In the latter case, try to recover by clobbering. */354 new_file = 1;355 write_buffer = NULL;356 resize_write_buffer(WRITE_BUFFER_SIZE);357 memset(write_buffer, 0, WRITE_BUFFER_SIZE);358 }359 360 /* gcda file, version, stamp checksum. */361 {362 uint8_t c3 = version >> 24;363 uint8_t c2 = (version >> 16) & 255;364 uint8_t c1 = (version >> 8) & 255;365 gcov_version = c3 >= 'A' ? (c3 - 'A') * 100 + (c2 - '0') * 10 + c1 - '0'366 : (c3 - '0') * 10 + c1 - '0';367 }368 write_32bit_value(GCOV_DATA_MAGIC);369 write_32bit_value(version);370 write_32bit_value(checksum);371 372#ifdef DEBUG_GCDAPROFILING373 fprintf(stderr, "llvmgcda: [%s]\n", orig_filename);374#endif375}376 377COMPILER_RT_VISIBILITY378void llvm_gcda_emit_function(uint32_t ident, uint32_t func_checksum,379 uint32_t cfg_checksum) {380 uint32_t len = 2;381 int use_extra_checksum = gcov_version >= 47;382 383 if (use_extra_checksum)384 len++;385#ifdef DEBUG_GCDAPROFILING386 fprintf(stderr, "llvmgcda: function id=0x%08x\n", ident);387#endif388 if (!output_file) return;389 390 /* function tag */391 write_32bit_value(GCOV_TAG_FUNCTION);392 write_32bit_value(len);393 write_32bit_value(ident);394 write_32bit_value(func_checksum);395 if (use_extra_checksum)396 write_32bit_value(cfg_checksum);397}398 399COMPILER_RT_VISIBILITY400void llvm_gcda_emit_arcs(uint32_t num_counters, uint64_t *counters) {401 uint32_t i;402 uint64_t *old_ctrs = NULL;403 uint32_t val = 0;404 uint64_t save_cur_pos = cur_pos;405 406 if (!output_file) return;407 408 val = read_32bit_value();409 410 if (val != (uint32_t)-1) {411 /* There are counters present in the file. Merge them. */412 if (val != GCOV_TAG_COUNTER_ARCS) {413 fprintf(stderr, "profiling: %s: cannot merge previous GCDA file: "414 "corrupt arc tag (0x%08x)\n",415 filename, val);416 return;417 }418 419 val = read_32bit_value();420 if (val == (uint32_t)-1 || val / 2 != num_counters) {421 fprintf(stderr, "profiling: %s: cannot merge previous GCDA file: "422 "mismatched number of counters (%d)\n",423 filename, val);424 return;425 }426 427 old_ctrs = malloc(sizeof(uint64_t) * num_counters);428 for (i = 0; i < num_counters; ++i)429 old_ctrs[i] = read_64bit_value();430 }431 432 cur_pos = save_cur_pos;433 434 /* Counter #1 (arcs) tag */435 write_32bit_value(GCOV_TAG_COUNTER_ARCS);436 write_32bit_value(num_counters * 2);437 for (i = 0; i < num_counters; ++i) {438 counters[i] += (old_ctrs ? old_ctrs[i] : 0);439 write_64bit_value(counters[i]);440 }441 442 free(old_ctrs);443 444#ifdef DEBUG_GCDAPROFILING445 fprintf(stderr, "llvmgcda: %u arcs\n", num_counters);446 for (i = 0; i < num_counters; ++i)447 fprintf(stderr, "llvmgcda: %llu\n", (unsigned long long)counters[i]);448#endif449}450 451COMPILER_RT_VISIBILITY452void llvm_gcda_summary_info(void) {453 uint32_t runs = 1;454 static uint32_t run_counted = 0; // We only want to increase the run count once.455 uint32_t val = 0;456 uint64_t save_cur_pos = cur_pos;457 458 if (!output_file) return;459 460 val = read_32bit_value();461 462 if (val != (uint32_t)-1) {463 /* There are counters present in the file. Merge them. */464 uint32_t gcov_tag =465 gcov_version >= 90 ? GCOV_TAG_OBJECT_SUMMARY : GCOV_TAG_PROGRAM_SUMMARY;466 if (val != gcov_tag) {467 fprintf(stderr,468 "profiling: %s: cannot merge previous run count: "469 "corrupt object tag (0x%08x)\n",470 filename, val);471 return;472 }473 474 val = read_32bit_value(); /* length */475 uint32_t prev_runs;476 if (gcov_version < 90) {477 read_32bit_value();478 read_32bit_value();479 prev_runs = read_32bit_value();480 } else {481 prev_runs = read_32bit_value();482 read_32bit_value();483 }484 for (uint32_t i = gcov_version < 90 ? 3 : 2; i < val; ++i)485 read_32bit_value();486 /* Add previous run count to new counter, if not already counted before. */487 runs = run_counted ? prev_runs : prev_runs + 1;488 }489 490 cur_pos = save_cur_pos;491 492 if (gcov_version >= 90) {493 write_32bit_value(GCOV_TAG_OBJECT_SUMMARY);494 write_32bit_value(2);495 write_32bit_value(runs);496 write_32bit_value(0); // sum_max497 } else {498 // Before gcov 4.8 (r190952), GCOV_TAG_SUMMARY_LENGTH was 9. r190952 set499 // GCOV_TAG_SUMMARY_LENGTH to 22. We simply use the smallest length which500 // can make gcov read "Runs:".501 write_32bit_value(GCOV_TAG_PROGRAM_SUMMARY);502 write_32bit_value(3);503 write_32bit_value(0);504 write_32bit_value(0);505 write_32bit_value(runs);506 }507 508 run_counted = 1;509 510#ifdef DEBUG_GCDAPROFILING511 fprintf(stderr, "llvmgcda: %u runs\n", runs);512#endif513}514 515COMPILER_RT_VISIBILITY516void llvm_gcda_end_file(void) {517 /* Write out EOF record. */518 if (output_file) {519 write_bytes("\0\0\0\0\0\0\0\0", 8);520 521 if (new_file) {522 fwrite(write_buffer, cur_pos, 1, output_file);523 free(write_buffer);524 } else {525 unmap_file();526 }527 528 fflush(output_file);529 lprofUnlockFd(fd);530 fclose(output_file);531 output_file = NULL;532 write_buffer = NULL;533 }534 free(filename);535 536#ifdef DEBUG_GCDAPROFILING537 fprintf(stderr, "llvmgcda: -----\n");538#endif539}540 541COMPILER_RT_VISIBILITY542void llvm_register_writeout_function(fn_ptr fn) {543 fn_list_insert(&writeout_fn_list, fn);544}545 546COMPILER_RT_VISIBILITY547void llvm_writeout_files(void) {548 struct fn_node *curr = writeout_fn_list.head;549 550 while (curr) {551 if (curr->id == CURRENT_ID) {552 curr->fn();553 }554 curr = curr->next;555 }556}557 558#ifndef _WIN32559// __attribute__((destructor)) and destructors whose priorities are greater than560// 100 run before this function and can thus be tracked. The priority is561// compatible with GCC 7 onwards.562#if __GNUC__ >= 9563#pragma GCC diagnostic ignored "-Wprio-ctor-dtor"564#endif565__attribute__((destructor(100)))566#endif567static void llvm_writeout_and_clear(void) {568 llvm_writeout_files();569 fn_list_remove(&writeout_fn_list);570}571 572COMPILER_RT_VISIBILITY573void llvm_register_reset_function(fn_ptr fn) {574 fn_list_insert(&reset_fn_list, fn);575}576 577COMPILER_RT_VISIBILITY578void llvm_delete_reset_function_list(void) { fn_list_remove(&reset_fn_list); }579 580COMPILER_RT_VISIBILITY581void llvm_reset_counters(void) {582 struct fn_node *curr = reset_fn_list.head;583 584 while (curr) {585 if (curr->id == CURRENT_ID) {586 curr->fn();587 }588 curr = curr->next;589 }590}591 592#if !defined(_WIN32) && !defined(__wasm__)593COMPILER_RT_VISIBILITY594pid_t __gcov_fork() {595 pid_t parent_pid = getpid();596 pid_t pid = fork();597 598 if (pid == 0) {599 pid_t child_pid = getpid();600 if (child_pid != parent_pid) {601 // The pid changed so we've a fork (one could have its own fork function)602 // Just reset the counters for this child process603 // threads.604 llvm_reset_counters();605 }606 }607 return pid;608}609#endif610 611COMPILER_RT_VISIBILITY612void llvm_gcov_init(fn_ptr wfn, fn_ptr rfn) {613 static int atexit_ran = 0;614 615 if (wfn)616 llvm_register_writeout_function(wfn);617 618 if (rfn)619 llvm_register_reset_function(rfn);620 621 if (atexit_ran == 0) {622 atexit_ran = 1;623 624 /* Make sure we write out the data and delete the data structures. */625 lprofAtExit(llvm_delete_reset_function_list);626#ifdef _WIN32627 lprofAtExit(llvm_writeout_and_clear);628#endif629 }630}631 632#if defined(_AIX)633COMPILER_RT_VISIBILITY __attribute__((constructor)) void634__llvm_profile_gcov_initialize() {635 const __llvm_gcov_init_func_struct *InitFuncStart =636 __llvm_profile_begin_covinit();637 const __llvm_gcov_init_func_struct *InitFuncEnd =638 __llvm_profile_end_covinit();639 640 for (const __llvm_gcov_init_func_struct *Ptr = InitFuncStart;641 Ptr != InitFuncEnd; ++Ptr) {642 fn_ptr wfn = (fn_ptr)Ptr->WriteoutFunction;643 fn_ptr rfn = (fn_ptr)Ptr->ResetFunction;644 if (!(wfn && rfn))645 continue;646 llvm_gcov_init(wfn, rfn);647 }648}649#endif650 651void __gcov_dump(void) {652 for (struct fn_node *f = writeout_fn_list.head; f; f = f->next)653 f->fn();654}655 656void __gcov_reset(void) {657 for (struct fn_node *f = reset_fn_list.head; f; f = f->next)658 f->fn();659}660 661#endif662