runtime/libprofile/EdgeProfiling.c

/*===-- EdgeProfiling.c - Support library for edge profiling --------------===*\
|*
|*                     The LLVM Compiler Infrastructure
|*
|* This file was developed by the LLVM research group and is distributed under
|* the University of Illinois Open Source License. See LICENSE.TXT for details.
|* 
|*===----------------------------------------------------------------------===*|
|* 
|* This file implements the call back routines for the edge profiling
|* instrumentation pass.  This should be used with the -insert-edge-profiling
|* LLVM pass.
|*
\*===----------------------------------------------------------------------===*/

#include "Profiling.h"
#include <stdlib.h>

static unsigned *ArrayStart;
static unsigned NumElements;

/* EdgeProfAtExitHandler - When the program exits, just write out the profiling
 * data.
 */
static void EdgeProfAtExitHandler() {
  /* Note that if this were doing something more intellegent with the
     instrumentation, that we could do some computation here to expand what we
     collected into simple edge profiles.  Since we directly count each edge, we
     just write out all of the counters directly.
  */
  write_profiling_data(Edge, ArrayStart, NumElements);
}


/* llvm_start_edge_profiling - This is the main entry point of the edge
 * profiling library.  It is responsible for setting up the atexit handler.
 */
int llvm_start_edge_profiling(int argc, const char **argv,
                              unsigned *arrayStart, unsigned numElements) {
  int Ret = save_arguments(argc, argv);
  ArrayStart = arrayStart;
  NumElements = numElements;
  atexit(EdgeProfAtExitHandler);
  return Ret;
}