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llvm-project/compiler-rt/lib/profile/GCDAProfiling.c

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/*===- GCDAProfiling.c - Support library for GCDA file emission -----------===*\
|*
|* Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|* See https://llvm.org/LICENSE.txt for license information.
|* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|*
|*===----------------------------------------------------------------------===*|
|*
|* This file implements the call back routines for the gcov profiling
|* instrumentation pass. Link against this library when running code through
|* the -insert-gcov-profiling LLVM pass.
|*
|* We emit files in a corrupt version of GCOV's "gcda" file format. These files
|* are only close enough that LCOV will happily parse them. Anything that lcov
|* ignores is missing.
|*
|* TODO: gcov is multi-process safe by having each exit open the existing file
|* and append to it. We'd like to achieve that and be thread-safe too.
|*
\*===----------------------------------------------------------------------===*/
#if !defined(__Fuchsia__)
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#if defined(_WIN32)
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include "WindowsMMap.h"
#else
#include <sys/file.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <unistd.h>
#endif
#if defined(__FreeBSD__) && defined(__i386__)
#define I386_FREEBSD 1
#else
#define I386_FREEBSD 0
#endif
#if !defined(_MSC_VER) && !I386_FREEBSD
#include <stdint.h>
#endif
#if defined(_MSC_VER)
typedef unsigned char uint8_t;
typedef unsigned int uint32_t;
typedef unsigned long long uint64_t;
#elif I386_FREEBSD
/* System headers define 'size_t' incorrectly on x64 FreeBSD (prior to
* FreeBSD 10, r232261) when compiled in 32-bit mode.
*/
typedef unsigned char uint8_t;
typedef unsigned int uint32_t;
typedef unsigned long long uint64_t;
#endif
#include "InstrProfiling.h"
#include "InstrProfilingUtil.h"
/* #define DEBUG_GCDAPROFILING */
enum {
GCOV_DATA_MAGIC = 0x67636461, // "gcda"
GCOV_TAG_FUNCTION = 0x01000000,
GCOV_TAG_COUNTER_ARCS = 0x01a10000,
// GCOV_TAG_OBJECT_SUMMARY superseded GCOV_TAG_PROGRAM_SUMMARY in GCC 9.
GCOV_TAG_OBJECT_SUMMARY = 0xa1000000,
GCOV_TAG_PROGRAM_SUMMARY = 0xa3000000,
};
/*
* --- GCOV file format I/O primitives ---
*/
/*
* The current file name we're outputting. Used primarily for error logging.
*/
static char *filename = NULL;
/*
* The current file we're outputting.
*/
static FILE *output_file = NULL;
/*
* Buffer that we write things into.
*/
#define WRITE_BUFFER_SIZE (128 * 1024)
static unsigned char *write_buffer = NULL;
static uint64_t cur_buffer_size = 0;
static uint64_t cur_pos = 0;
static uint64_t file_size = 0;
static int new_file = 0;
static int gcov_version;
#if defined(_WIN32)
static HANDLE mmap_handle = NULL;
#endif
static int fd = -1;
typedef void (*fn_ptr)();
typedef void* dynamic_object_id;
// The address of this variable identifies a given dynamic object.
static dynamic_object_id current_id;
#define CURRENT_ID (&current_id)
struct fn_node {
dynamic_object_id id;
fn_ptr fn;
struct fn_node* next;
};
struct fn_list {
struct fn_node *head, *tail;
};
/*
* A list of functions to write out the data, shared between all dynamic objects.
*/
struct fn_list writeout_fn_list;
/*
* A list of flush functions that our __gcov_flush() function should call, shared between all dynamic objects.
*/
struct fn_list flush_fn_list;
/*
* A list of reset functions, shared between all dynamic objects.
*/
struct fn_list reset_fn_list;
static void fn_list_insert(struct fn_list* list, fn_ptr fn) {
struct fn_node* new_node = malloc(sizeof(struct fn_node));
new_node->fn = fn;
new_node->next = NULL;
new_node->id = CURRENT_ID;
if (!list->head) {
list->head = list->tail = new_node;
} else {
list->tail->next = new_node;
list->tail = new_node;
}
}
static void fn_list_remove(struct fn_list* list) {
struct fn_node* curr = list->head;
struct fn_node* prev = NULL;
struct fn_node* next = NULL;
while (curr) {
next = curr->next;
if (curr->id == CURRENT_ID) {
if (curr == list->head) {
list->head = next;
}
if (curr == list->tail) {
list->tail = prev;
}
if (prev) {
prev->next = next;
}
free(curr);
} else {
prev = curr;
}
curr = next;
}
}
static void resize_write_buffer(uint64_t size) {
if (!new_file) return;
size += cur_pos;
if (size <= cur_buffer_size) return;
size = (size - 1) / WRITE_BUFFER_SIZE + 1;
size *= WRITE_BUFFER_SIZE;
write_buffer = realloc(write_buffer, size);
cur_buffer_size = size;
}
static void write_bytes(const char *s, size_t len) {
resize_write_buffer(len);
memcpy(&write_buffer[cur_pos], s, len);
cur_pos += len;
}
static void write_32bit_value(uint32_t i) {
write_bytes((char*)&i, 4);
}
static void write_64bit_value(uint64_t i) {
// GCOV uses a lo-/hi-word format even on big-endian systems.
// See also GCOVBuffer::readInt64 in LLVM.
uint32_t lo = (uint32_t) i;
uint32_t hi = (uint32_t) (i >> 32);
write_32bit_value(lo);
write_32bit_value(hi);
}
static uint32_t length_of_string(const char *s) {
return (strlen(s) / 4) + 1;
}
// Remove when we support libgcov 9 current_working_directory.
#if !defined(_MSC_VER) && defined(__clang__)
__attribute__((unused))
#endif
static void
write_string(const char *s) {
uint32_t len = length_of_string(s);
write_32bit_value(len);
write_bytes(s, strlen(s));
write_bytes("\0\0\0\0", 4 - (strlen(s) % 4));
}
static uint32_t read_32bit_value() {
uint32_t val;
if (new_file)
return (uint32_t)-1;
val = *(uint32_t*)&write_buffer[cur_pos];
cur_pos += 4;
return val;
}
static uint64_t read_64bit_value() {
// GCOV uses a lo-/hi-word format even on big-endian systems.
// See also GCOVBuffer::readInt64 in LLVM.
uint32_t lo = read_32bit_value();
uint32_t hi = read_32bit_value();
return ((uint64_t)hi << 32) | ((uint64_t)lo);
}
static char *mangle_filename(const char *orig_filename) {
char *new_filename;
size_t prefix_len;
int prefix_strip;
const char *prefix = lprofGetPathPrefix(&prefix_strip, &prefix_len);
if (prefix == NULL)
return strdup(orig_filename);
new_filename = malloc(prefix_len + 1 + strlen(orig_filename) + 1);
lprofApplyPathPrefix(new_filename, orig_filename, prefix, prefix_len,
prefix_strip);
return new_filename;
}
static int map_file() {
fseek(output_file, 0L, SEEK_END);
file_size = ftell(output_file);
/* A size of 0 means the file has been created just now (possibly by another
* process in lock-after-open race condition). No need to mmap. */
if (file_size == 0)
return -1;
#if defined(_WIN32)
HANDLE mmap_fd;
if (fd == -1)
mmap_fd = INVALID_HANDLE_VALUE;
else
mmap_fd = (HANDLE)_get_osfhandle(fd);
mmap_handle = CreateFileMapping(mmap_fd, NULL, PAGE_READWRITE, DWORD_HI(file_size), DWORD_LO(file_size), NULL);
if (mmap_handle == NULL) {
fprintf(stderr, "profiling: %s: cannot create file mapping: %lu\n",
filename, GetLastError());
return -1;
}
write_buffer = MapViewOfFile(mmap_handle, FILE_MAP_WRITE, 0, 0, file_size);
if (write_buffer == NULL) {
fprintf(stderr, "profiling: %s: cannot map: %lu\n", filename,
GetLastError());
CloseHandle(mmap_handle);
return -1;
}
#else
write_buffer = mmap(0, file_size, PROT_READ | PROT_WRITE,
MAP_FILE | MAP_SHARED, fd, 0);
if (write_buffer == (void *)-1) {
int errnum = errno;
fprintf(stderr, "profiling: %s: cannot map: %s\n", filename,
strerror(errnum));
return -1;
}
#endif
return 0;
}
static void unmap_file() {
#if defined(_WIN32)
if (!FlushViewOfFile(write_buffer, file_size)) {
fprintf(stderr, "profiling: %s: cannot flush mapped view: %lu\n", filename,
GetLastError());
}
if (!UnmapViewOfFile(write_buffer)) {
fprintf(stderr, "profiling: %s: cannot unmap mapped view: %lu\n", filename,
GetLastError());
}
if (!CloseHandle(mmap_handle)) {
fprintf(stderr, "profiling: %s: cannot close file mapping handle: %lu\n",
filename, GetLastError());
}
mmap_handle = NULL;
#else
if (msync(write_buffer, file_size, MS_SYNC) == -1) {
int errnum = errno;
fprintf(stderr, "profiling: %s: cannot msync: %s\n", filename,
strerror(errnum));
}
/* We explicitly ignore errors from unmapping because at this point the data
* is written and we don't care.
*/
(void)munmap(write_buffer, file_size);
#endif
write_buffer = NULL;
file_size = 0;
}
/*
* --- LLVM line counter API ---
*/
/* A file in this case is a translation unit. Each .o file built with line
* profiling enabled will emit to a different file. Only one file may be
* started at a time.
*/
COMPILER_RT_VISIBILITY
void llvm_gcda_start_file(const char *orig_filename, uint32_t version,
uint32_t checksum) {
const char *mode = "r+b";
filename = mangle_filename(orig_filename);
/* Try just opening the file. */
fd = open(filename, O_RDWR | O_BINARY);
if (fd == -1) {
/* Try creating the file. */
fd = open(filename, O_RDWR | O_CREAT | O_EXCL | O_BINARY, 0644);
if (fd != -1) {
mode = "w+b";
} else {
/* Try creating the directories first then opening the file. */
__llvm_profile_recursive_mkdir(filename);
fd = open(filename, O_RDWR | O_CREAT | O_EXCL | O_BINARY, 0644);
if (fd != -1) {
mode = "w+b";
} else {
/* Another process may have created the file just now.
* Try opening it without O_CREAT and O_EXCL. */
fd = open(filename, O_RDWR | O_BINARY);
if (fd == -1) {
/* Bah! It's hopeless. */
int errnum = errno;
fprintf(stderr, "profiling: %s: cannot open: %s\n", filename,
strerror(errnum));
return;
}
}
}
}
/* Try to flock the file to serialize concurrent processes writing out to the
* same GCDA. This can fail if the filesystem doesn't support it, but in that
* case we'll just carry on with the old racy behaviour and hope for the best.
*/
lprofLockFd(fd);
output_file = fdopen(fd, mode);
/* Initialize the write buffer. */
new_file = 0;
write_buffer = NULL;
cur_buffer_size = 0;
cur_pos = 0;
if (map_file() == -1) {
/* The file has been created just now (file_size == 0) or mmap failed
* unexpectedly. In the latter case, try to recover by clobbering. */
new_file = 1;
write_buffer = NULL;
resize_write_buffer(WRITE_BUFFER_SIZE);
memset(write_buffer, 0, WRITE_BUFFER_SIZE);
}
/* gcda file, version, stamp checksum. */
{
uint8_t c3 = version >> 24;
uint8_t c2 = (version >> 16) & 255;
uint8_t c1 = (version >> 8) & 255;
gcov_version = c3 >= 'A' ? (c3 - 'A') * 100 + (c2 - '0') * 10 + c1 - '0'
: (c3 - '0') * 10 + c1 - '0';
}
write_32bit_value(GCOV_DATA_MAGIC);
write_32bit_value(version);
write_32bit_value(checksum);
#ifdef DEBUG_GCDAPROFILING
fprintf(stderr, "llvmgcda: [%s]\n", orig_filename);
#endif
}
/* Given an array of pointers to counters (counters), increment the n-th one,
* where we're also given a pointer to n (predecessor).
*/
COMPILER_RT_VISIBILITY
void llvm_gcda_increment_indirect_counter(uint32_t *predecessor,
uint64_t **counters) {
uint64_t *counter;
uint32_t pred;
pred = *predecessor;
if (pred == 0xffffffff)
return;
counter = counters[pred];
/* Don't crash if the pred# is out of sync. This can happen due to threads,
or because of a TODO in GCOVProfiling.cpp buildEdgeLookupTable(). */
if (counter)
++*counter;
#ifdef DEBUG_GCDAPROFILING
else
fprintf(stderr,
"llvmgcda: increment_indirect_counter counters=%08llx, pred=%u\n",
*counter, *predecessor);
#endif
}
COMPILER_RT_VISIBILITY
void llvm_gcda_emit_function(uint32_t ident, uint32_t func_checksum,
uint32_t cfg_checksum) {
uint32_t len = 2;
int use_extra_checksum = gcov_version >= 47;
if (use_extra_checksum)
len++;
#ifdef DEBUG_GCDAPROFILING
fprintf(stderr, "llvmgcda: function id=0x%08x\n", ident);
#endif
if (!output_file) return;
/* function tag */
write_32bit_value(GCOV_TAG_FUNCTION);
write_32bit_value(len);
write_32bit_value(ident);
write_32bit_value(func_checksum);
if (use_extra_checksum)
write_32bit_value(cfg_checksum);
}
COMPILER_RT_VISIBILITY
void llvm_gcda_emit_arcs(uint32_t num_counters, uint64_t *counters) {
uint32_t i;
uint64_t *old_ctrs = NULL;
uint32_t val = 0;
uint64_t save_cur_pos = cur_pos;
if (!output_file) return;
val = read_32bit_value();
if (val != (uint32_t)-1) {
/* There are counters present in the file. Merge them. */
if (val != GCOV_TAG_COUNTER_ARCS) {
fprintf(stderr, "profiling: %s: cannot merge previous GCDA file: "
"corrupt arc tag (0x%08x)\n",
filename, val);
return;
}
val = read_32bit_value();
if (val == (uint32_t)-1 || val / 2 != num_counters) {
fprintf(stderr, "profiling: %s: cannot merge previous GCDA file: "
"mismatched number of counters (%d)\n",
filename, val);
return;
}
old_ctrs = malloc(sizeof(uint64_t) * num_counters);
for (i = 0; i < num_counters; ++i)
old_ctrs[i] = read_64bit_value();
}
cur_pos = save_cur_pos;
/* Counter #1 (arcs) tag */
write_32bit_value(GCOV_TAG_COUNTER_ARCS);
write_32bit_value(num_counters * 2);
for (i = 0; i < num_counters; ++i) {
counters[i] += (old_ctrs ? old_ctrs[i] : 0);
write_64bit_value(counters[i]);
}
free(old_ctrs);
#ifdef DEBUG_GCDAPROFILING
fprintf(stderr, "llvmgcda: %u arcs\n", num_counters);
for (i = 0; i < num_counters; ++i)
fprintf(stderr, "llvmgcda: %llu\n", (unsigned long long)counters[i]);
#endif
}
COMPILER_RT_VISIBILITY
void llvm_gcda_summary_info() {
uint32_t runs = 1;
static uint32_t run_counted = 0; // We only want to increase the run count once.
uint32_t val = 0;
uint64_t save_cur_pos = cur_pos;
if (!output_file) return;
val = read_32bit_value();
if (val != (uint32_t)-1) {
/* There are counters present in the file. Merge them. */
if (val != (gcov_version >= 90 ? GCOV_TAG_OBJECT_SUMMARY
: GCOV_TAG_PROGRAM_SUMMARY)) {
fprintf(stderr,
"profiling: %s: cannot merge previous run count: "
"corrupt object tag (0x%08x)\n",
filename, val);
return;
}
val = read_32bit_value(); /* length */
uint32_t prev_runs;
if (gcov_version < 90) {
read_32bit_value();
read_32bit_value();
prev_runs = read_32bit_value();
} else {
prev_runs = read_32bit_value();
read_32bit_value();
}
for (uint32_t i = gcov_version < 90 ? 3 : 2; i < val; ++i)
read_32bit_value();
/* Add previous run count to new counter, if not already counted before. */
runs = run_counted ? prev_runs : prev_runs + 1;
}
cur_pos = save_cur_pos;
if (gcov_version >= 90) {
write_32bit_value(GCOV_TAG_OBJECT_SUMMARY);
write_32bit_value(2);
write_32bit_value(runs);
write_32bit_value(0); // sum_max
} else {
// Before gcov 4.8 (r190952), GCOV_TAG_SUMMARY_LENGTH was 9. r190952 set
// GCOV_TAG_SUMMARY_LENGTH to 22. We simply use the smallest length which
// can make gcov read "Runs:".
write_32bit_value(GCOV_TAG_PROGRAM_SUMMARY);
write_32bit_value(3);
write_32bit_value(0);
write_32bit_value(0);
write_32bit_value(runs);
}
run_counted = 1;
#ifdef DEBUG_GCDAPROFILING
fprintf(stderr, "llvmgcda: %u runs\n", runs);
#endif
}
COMPILER_RT_VISIBILITY
void llvm_gcda_end_file() {
/* Write out EOF record. */
if (output_file) {
write_bytes("\0\0\0\0\0\0\0\0", 8);
if (new_file) {
fwrite(write_buffer, cur_pos, 1, output_file);
free(write_buffer);
} else {
unmap_file();
}
fflush(output_file);
lprofUnlockFd(fd);
fclose(output_file);
output_file = NULL;
write_buffer = NULL;
}
free(filename);
#ifdef DEBUG_GCDAPROFILING
fprintf(stderr, "llvmgcda: -----\n");
#endif
}
COMPILER_RT_VISIBILITY
void llvm_register_writeout_function(fn_ptr fn) {
fn_list_insert(&writeout_fn_list, fn);
}
COMPILER_RT_VISIBILITY
void llvm_writeout_files(void) {
struct fn_node *curr = writeout_fn_list.head;
while (curr) {
if (curr->id == CURRENT_ID) {
curr->fn();
}
curr = curr->next;
}
}
#ifndef _WIN32
// __attribute__((destructor)) and destructors whose priorities are greater than
// 100 run before this function and can thus be tracked. The priority is
// compatible with GCC 7 onwards.
__attribute__((destructor(100)))
#endif
static void llvm_writeout_and_clear(void) {
llvm_writeout_files();
fn_list_remove(&writeout_fn_list);
}
COMPILER_RT_VISIBILITY
void llvm_register_flush_function(fn_ptr fn) {
fn_list_insert(&flush_fn_list, fn);
}
void __gcov_flush() {
struct fn_node* curr = flush_fn_list.head;
while (curr) {
curr->fn();
curr = curr->next;
}
}
COMPILER_RT_VISIBILITY
void llvm_delete_flush_function_list(void) {
fn_list_remove(&flush_fn_list);
}
COMPILER_RT_VISIBILITY
void llvm_register_reset_function(fn_ptr fn) {
fn_list_insert(&reset_fn_list, fn);
}
COMPILER_RT_VISIBILITY
void llvm_delete_reset_function_list(void) { fn_list_remove(&reset_fn_list); }
COMPILER_RT_VISIBILITY
void llvm_reset_counters(void) {
struct fn_node *curr = reset_fn_list.head;
while (curr) {
if (curr->id == CURRENT_ID) {
curr->fn();
}
curr = curr->next;
}
}
#if !defined(_WIN32)
COMPILER_RT_VISIBILITY
pid_t __gcov_fork() {
pid_t parent_pid = getpid();
pid_t pid = fork();
if (pid == 0) {
pid_t child_pid = getpid();
if (child_pid != parent_pid) {
// The pid changed so we've a fork (one could have its own fork function)
// Just reset the counters for this child process
// threads.
llvm_reset_counters();
}
}
return pid;
}
#endif
COMPILER_RT_VISIBILITY
void llvm_gcov_init(fn_ptr wfn, fn_ptr ffn, fn_ptr rfn) {
static int atexit_ran = 0;
if (wfn)
llvm_register_writeout_function(wfn);
if (ffn)
llvm_register_flush_function(ffn);
if (rfn)
llvm_register_reset_function(rfn);
if (atexit_ran == 0) {
atexit_ran = 1;
/* Make sure we write out the data and delete the data structures. */
atexit(llvm_delete_reset_function_list);
atexit(llvm_delete_flush_function_list);
#ifdef _WIN32
atexit(llvm_writeout_and_clear);
#endif
}
}
#endif
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