runtime/libprofile/BlockProfiling.c

/*===-- BlockProfiling.c - Support library for block 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 block profiling
|* instrumentation pass.  This should be used with the -insert-block-profiling
|* LLVM pass.
|*
\*===----------------------------------------------------------------------===*/

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

static unsigned *ArrayStart;
static unsigned NumElements;

/* BlockProfAtExitHandler - When the program exits, just write out the profiling
 * data.
 */
static void BlockProfAtExitHandler() {
  /* 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 block profiles.  Since we directly count each block,
  */
  write_profiling_data(Block, ArrayStart, NumElements);
}


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