toolchain-extras/profile-clang-extras.cpp

/*
 * Copyright (C) 2020 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <errno.h>
#include <signal.h>
#include <stdlib.h>

#include "profile-extras.h"

extern "C" {

static sighandler_t chained_signal_handler = SIG_ERR;

#ifndef __CONTINUOUS_COVERAGE_MODE__
int __llvm_profile_write_file(void);
#endif  // __CONTINUOUS_COVERAGE_MODE__

static void llvm_signal_handler(__unused int signum) {
  // TODO(pirama) Only disable __llvm_profile_write_file call to begin with.
  // After continuous mode is stable, stop registering the signal handler.
#ifndef __CONTINUOUS_COVERAGE_MODE__
  __llvm_profile_write_file();
#endif  // __CONTINUOUS_COVERAGE_MODE__

  if (chained_signal_handler != SIG_ERR && chained_signal_handler != SIG_IGN &&
      chained_signal_handler != SIG_DFL) {
    (chained_signal_handler)(signum);
  }
}

// Initialize libprofile-extras:
//
// - Install a signal handler that triggers __llvm_profile_write_file on
// <COVERAGE_FLUSH_SIGNAL>.
//
// We want this initializer to run during load time.  In addition to marking
// this function as a constructor, we link this library with `--whole-archive`
// to force this function to be included in the output.
static __attribute__((constructor)) int init_profile_extras(void) {
  if (chained_signal_handler != SIG_ERR) {
    return -1;
  }
  sighandler_t ret1 = signal(COVERAGE_FLUSH_SIGNAL, llvm_signal_handler);
  if (ret1 == SIG_ERR) {
    return -1;
  }
  chained_signal_handler = ret1;

  return 0;
}
}