text: /*===- GCDAProfiling.c - Support library for GCDA file emission -----------===*\
  |*
  |*                     The LLVM Compiler Infrastructure
  |*
  |* This file is distributed under the University of Illinois Open Source
  |* License. See LICENSE.TXT for details.
  |* 
  |*===----------------------------------------------------------------------===*|
  |* 
  |* 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.
  |*
  \*===----------------------------------------------------------------------===*/
  
  #include "InstrProfilingUtil.h"
  
  #include <errno.h>
  #include <fcntl.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  #if defined(_WIN32)
  #include "WindowsMMap.h"
  #else
  #include <sys/mman.h>
  #include <sys/file.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
  
  /* #define DEBUG_GCDAPROFILING */
  
  /*
   * --- 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 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 fd = -1;
  
  /*
   * A list of functions to write out the data.
   */
  typedef void (*writeout_fn)();
  
  struct writeout_fn_node {
    writeout_fn fn;
    struct writeout_fn_node *next;
  };
  
  static struct writeout_fn_node *writeout_fn_head = NULL;
  static struct writeout_fn_node *writeout_fn_tail = NULL;
  
  /*
   *  A list of flush functions that our __gcov_flush() function should call.
   */
  typedef void (*flush_fn)();
  
  struct flush_fn_node {
    flush_fn fn;
    struct flush_fn_node *next;
  };
  
  static struct flush_fn_node *flush_fn_head = NULL;
  static struct flush_fn_node *flush_fn_tail = NULL;
  
  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) {
    write_bytes((char*)&i, 8);
  }
  
  static uint32_t length_of_string(const char *s) {
    return (strlen(s) / 4) + 1;
  }
  
  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() {
    uint64_t val;
  
    if (new_file)
      return (uint64_t)-1;
  
    val = *(uint64_t*)&write_buffer[cur_pos];
    cur_pos += 8;
    return val;
  }
  
  static char *mangle_filename(const char *orig_filename) {
    char *new_filename;
    size_t filename_len, prefix_len;
    int prefix_strip;
    int level = 0;
    const char *fname, *ptr;
    const char *prefix = getenv("GCOV_PREFIX");
    const char *prefix_strip_str = getenv("GCOV_PREFIX_STRIP");
  
    if (prefix == NULL || prefix[0] == '\0')
      return strdup(orig_filename);
  
    if (prefix_strip_str) {
      prefix_strip = atoi(prefix_strip_str);
  
      /* Negative GCOV_PREFIX_STRIP values are ignored */
      if (prefix_strip < 0)
        prefix_strip = 0;
    } else {
      prefix_strip = 0;
    }
  
    fname = orig_filename;
    for (level = 0, ptr = fname + 1; level < prefix_strip; ++ptr) {
      if (*ptr == '\0')
        break;
      if (*ptr != '/')
        continue;
      fname = ptr;
      ++level;
    }
  
    filename_len = strlen(fname);
    prefix_len = strlen(prefix);
    new_filename = malloc(prefix_len + 1 + filename_len + 1);
    memcpy(new_filename, prefix, prefix_len);
  
    if (prefix[prefix_len - 1] != '/')
      new_filename[prefix_len++] = '/';
    memcpy(new_filename + prefix_len, fname, filename_len + 1);
  
    return new_filename;
  }
  
  static int map_file() {
    fseek(output_file, 0L, SEEK_END);
    file_size = ftell(output_file);
  
    /* A size of 0 is invalid to `mmap'. Return a fail here, but don't issue an
     * error message because it should "just work" for the user. */
    if (file_size == 0)
      return -1;
  
    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;
    }
    return 0;
  }
  
  static void unmap_file() {
    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);
    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.
   */
  void llvm_gcda_start_file(const char *orig_filename, const char version[4],
                            uint32_t checksum) {
    const char *mode = "r+b";
    filename = mangle_filename(orig_filename);
  
    /* Try just opening the file. */
    new_file = 0;
    fd = open(filename, O_RDWR);
  
    if (fd == -1) {
      /* Try opening the file, creating it if necessary. */
      new_file = 1;
      mode = "w+b";
      fd = open(filename, O_RDWR | O_CREAT, 0644);
      if (fd == -1) {
        /* Try creating the directories first then opening the file. */
        __llvm_profile_recursive_mkdir(filename);
        fd = open(filename, O_RDWR | O_CREAT, 0644);
        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.
     */
    flock(fd, LOCK_EX);
    output_file = fdopen(fd, mode);
  
    /* Initialize the write buffer. */
    write_buffer = NULL;
    cur_buffer_size = 0;
    cur_pos = 0;
  
    if (new_file) {
      resize_write_buffer(WRITE_BUFFER_SIZE);
      memset(write_buffer, 0, WRITE_BUFFER_SIZE);
    } else {
      if (map_file() == -1) {
        /* mmap failed, try to recover by clobbering */
        new_file = 1;
        write_buffer = NULL;
        cur_buffer_size = 0;
        resize_write_buffer(WRITE_BUFFER_SIZE);
        memset(write_buffer, 0, WRITE_BUFFER_SIZE);
      }
    }
  
    /* gcda file, version, stamp checksum. */
    write_bytes("adcg", 4);
    write_bytes(version, 4);
    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).
   */
  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
  }
  
  void llvm_gcda_emit_function(uint32_t ident, const char *function_name,
                               uint32_t func_checksum, uint8_t use_extra_checksum,
                               uint32_t cfg_checksum) {
    uint32_t len = 2;
  
    if (use_extra_checksum)
      len++;
  #ifdef DEBUG_GCDAPROFILING
    fprintf(stderr, "llvmgcda: function id=0x%08x name=%s\n", ident,
            function_name ? function_name : "NULL");
  #endif
    if (!output_file) return;
  
    /* function tag */
    write_bytes("\0\0\0\1", 4);
    if (function_name)
      len += 1 + length_of_string(function_name);
    write_32bit_value(len);
    write_32bit_value(ident);
    write_32bit_value(func_checksum);
    if (use_extra_checksum)
      write_32bit_value(cfg_checksum);
    if (function_name)
      write_string(function_name);
  }
  
  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 != 0x01a10000) {
        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_bytes("\0\0\xa1\1", 4);
    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
  }
  
  void llvm_gcda_summary_info() {
    const uint32_t obj_summary_len = 9; /* Length for gcov compatibility. */
    uint32_t i;
    uint32_t runs = 1;
    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 != 0xa1000000) {
        fprintf(stderr, "profiling: %s: cannot merge previous run count: "
                        "corrupt object tag (0x%08x)\n",
                filename, val);
        return;
      }
  
      val = read_32bit_value(); /* length */
      if (val != obj_summary_len) {
        fprintf(stderr, "profiling: %s: cannot merge previous run count: "
                        "mismatched object length (%d)\n",
                filename, val);
        return;
      }
  
      read_32bit_value(); /* checksum, unused */
      read_32bit_value(); /* num, unused */
      runs += read_32bit_value(); /* Add previous run count to new counter. */
    }
  
    cur_pos = save_cur_pos;
  
    /* Object summary tag */
    write_bytes("\0\0\0\xa1", 4);
    write_32bit_value(obj_summary_len);
    write_32bit_value(0); /* checksum, unused */
    write_32bit_value(0); /* num, unused */
    write_32bit_value(runs);
    for (i = 3; i < obj_summary_len; ++i)
      write_32bit_value(0);
  
    /* Program summary tag */
    write_bytes("\0\0\0\xa3", 4); /* tag indicates 1 program */
    write_32bit_value(0); /* 0 length */
  
  #ifdef DEBUG_GCDAPROFILING
    fprintf(stderr, "llvmgcda:   %u runs\n", runs);
  #endif
  }
  
  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();
      }
  
      fclose(output_file);
      flock(fd, LOCK_UN);
      output_file = NULL;
      write_buffer = NULL;
    }
    free(filename);
  
  #ifdef DEBUG_GCDAPROFILING
    fprintf(stderr, "llvmgcda: -----\n");
  #endif
  }
  
  void llvm_register_writeout_function(writeout_fn fn) {
    struct writeout_fn_node *new_node = malloc(sizeof(struct writeout_fn_node));
    new_node->fn = fn;
    new_node->next = NULL;
  
    if (!writeout_fn_head) {
      writeout_fn_head = writeout_fn_tail = new_node;
    } else {
      writeout_fn_tail->next = new_node;
      writeout_fn_tail = new_node;
    }
  }
  
  void llvm_writeout_files(void) {
    struct writeout_fn_node *curr = writeout_fn_head;
  
    while (curr) {
      curr->fn();
      curr = curr->next;
    }
  }
  
  void llvm_delete_writeout_function_list(void) {
    while (writeout_fn_head) {
      struct writeout_fn_node *node = writeout_fn_head;
      writeout_fn_head = writeout_fn_head->next;
      free(node);
    }
    
    writeout_fn_head = writeout_fn_tail = NULL;
  }
  
  void llvm_register_flush_function(flush_fn fn) {
    struct flush_fn_node *new_node = malloc(sizeof(struct flush_fn_node));
    new_node->fn = fn;
    new_node->next = NULL;
  
    if (!flush_fn_head) {
      flush_fn_head = flush_fn_tail = new_node;
    } else {
      flush_fn_tail->next = new_node;
      flush_fn_tail = new_node;
    }
  }
  
  void __gcov_flush() {
    struct flush_fn_node *curr = flush_fn_head;
  
    while (curr) {
      curr->fn();
      curr = curr->next;
    }
  }
  
  void llvm_delete_flush_function_list(void) {
    while (flush_fn_head) {
      struct flush_fn_node *node = flush_fn_head;
      flush_fn_head = flush_fn_head->next;
      free(node);
    }
  
    flush_fn_head = flush_fn_tail = NULL;
  }
  
  void llvm_gcov_init(writeout_fn wfn, flush_fn ffn) {
    static int atexit_ran = 0;
  
    if (wfn)
      llvm_register_writeout_function(wfn);
  
    if (ffn)
      llvm_register_flush_function(ffn);
  
    if (atexit_ran == 0) {
      atexit_ran = 1;
  
      /* Make sure we write out the data and delete the data structures. */
      atexit(llvm_delete_flush_function_list);
      atexit(llvm_delete_writeout_function_list);
      atexit(llvm_writeout_files);
    }
  }
  