Commit e7aab320 authored by Vedant Kumar's avatar Vedant Kumar
Browse files

[profile] Factor out logic for mmap'ing merged profile, NFC 

Split out the logic to get the size of a merged profile and to do a
compatibility check. This can be shared with both the continuous+merging
mode implementation, as well as the runtime-allocated counters
implementation planned for Fuchsia.

Lifted out of D69586.

Differential Revision: https://reviews.llvm.org/D70135
parent 3d6b5398

compiler-rt/lib/profile/InstrProfilingFile.c

+51 −22
Original line number Diff line number Diff line
@@ -171,21 +171,18 @@ static void setupIOBuffer() { 
  }

}



/* Read profile data in \c ProfileFile and merge with in-memory

   profile counters. Returns -1 if there is fatal error, otheriwse

   0 is returned. Returning 0 does not mean merge is actually

   performed. If merge is actually done, *MergeDone is set to 1.

*/

static int doProfileMerging(FILE *ProfileFile, int *MergeDone) {

  uint64_t ProfileFileSize;

  char *ProfileBuffer;



/* Get the size of the profile file. If there are any errors, print the

 * message under the assumption that the profile is being read for merging

 * purposes, and return -1. Otherwise return the file size in the inout param

 * \p ProfileFileSize. */

static int getProfileFileSizeForMerging(FILE *ProfileFile,

                                        uint64_t *ProfileFileSize) {

  if (fseek(ProfileFile, 0L, SEEK_END) == -1) {

    PROF_ERR("Unable to merge profile data, unable to get size: %s\n",

             strerror(errno));

    return -1;

  }

  ProfileFileSize = ftell(ProfileFile);

  *ProfileFileSize = ftell(ProfileFile);



  /* Restore file offset.  */

  if (fseek(ProfileFile, 0L, SEEK_SET) == -1) {
@@ -194,29 +191,61 @@ static int doProfileMerging(FILE *ProfileFile, int *MergeDone) { 
    return -1;

  }



  /* Nothing to merge.  */

  if (ProfileFileSize < sizeof(__llvm_profile_header)) {

    if (ProfileFileSize)

  if (*ProfileFileSize > 0 &&

      *ProfileFileSize < sizeof(__llvm_profile_header)) {

    PROF_WARN("Unable to merge profile data: %s\n",

              "source profile file is too small.");

    return -1;

  }

  return 0;

}



  ProfileBuffer = mmap(NULL, ProfileFileSize, PROT_READ, MAP_SHARED | MAP_FILE,

/* mmap() \p ProfileFile for profile merging purposes, assuming that an

 * exclusive lock is held on the file and that \p ProfileFileSize is the

 * length of the file. Return the mmap'd buffer in the inout variable

 * \p ProfileBuffer. Returns -1 on failure. On success, the caller is

 * responsible for unmapping the mmap'd buffer in \p ProfileBuffer. */

static int mmapProfileForMerging(FILE *ProfileFile, uint64_t ProfileFileSize,

                                 char **ProfileBuffer) {

  *ProfileBuffer = mmap(NULL, ProfileFileSize, PROT_READ, MAP_SHARED | MAP_FILE,

                        fileno(ProfileFile), 0);

  if (ProfileBuffer == MAP_FAILED) {

  if (*ProfileBuffer == MAP_FAILED) {

    PROF_ERR("Unable to merge profile data, mmap failed: %s\n",

             strerror(errno));

    return -1;

  }



  if (__llvm_profile_check_compatibility(ProfileBuffer, ProfileFileSize)) {

    (void)munmap(ProfileBuffer, ProfileFileSize);

  if (__llvm_profile_check_compatibility(*ProfileBuffer, ProfileFileSize)) {

    (void)munmap(*ProfileBuffer, ProfileFileSize);

    PROF_WARN("Unable to merge profile data: %s\n",

              "source profile file is not compatible.");

    return -1;

  }

  return 0;

}



/* Read profile data in \c ProfileFile and merge with in-memory

   profile counters. Returns -1 if there is fatal error, otheriwse

   0 is returned. Returning 0 does not mean merge is actually

   performed. If merge is actually done, *MergeDone is set to 1.

*/

static int doProfileMerging(FILE *ProfileFile, int *MergeDone) {

  uint64_t ProfileFileSize;

  char *ProfileBuffer;



  /* Get the size of the profile on disk. */

  if (getProfileFileSizeForMerging(ProfileFile, &ProfileFileSize) == -1)

    return -1;



  /* Nothing to merge.  */

  if (!ProfileFileSize)

    return 0;



  /* mmap() the profile and check that it is compatible with the data in

   * the current image. */

  if (mmapProfileForMerging(ProfileFile, ProfileFileSize, &ProfileBuffer) == -1)

    return -1;



  /* Now start merging */

  __llvm_profile_merge_from_buffer(ProfileBuffer, ProfileFileSize);