1/*===-- BasicBlockTracing.c - Support library for basic block tracing -----===*\
2|*
3|*                     The LLVM Compiler Infrastructure
4|*
5|* This file is distributed under the University of Illinois Open Source
6|* License. See LICENSE.TXT for details.
7|*
8|*===----------------------------------------------------------------------===*|
9|*
10|* This file implements the call back routines for the basic block tracing
11|* instrumentation pass.  This should be used with the -trace-basic-blocks
12|* LLVM pass.
13|*
14\*===----------------------------------------------------------------------===*/
15
16#include "Profiling.h"
17#include <stdlib.h>
18#include <stdio.h>
19
20static unsigned *ArrayStart, *ArrayEnd, *ArrayCursor;
21
22/* WriteAndFlushBBTraceData - write out the currently accumulated trace data
23 * and reset the cursor to point to the beginning of the buffer.
24 */
25static void WriteAndFlushBBTraceData () {
26  write_profiling_data(BBTraceInfo, ArrayStart, (ArrayCursor - ArrayStart));
27  ArrayCursor = ArrayStart;
28}
29
30/* BBTraceAtExitHandler - When the program exits, just write out any remaining
31 * data and free the trace buffer.
32 */
33static void BBTraceAtExitHandler(void) {
34  WriteAndFlushBBTraceData ();
35  free (ArrayStart);
36}
37
38/* llvm_trace_basic_block - called upon hitting a new basic block. */
39void llvm_trace_basic_block (unsigned BBNum) {
40  *ArrayCursor++ = BBNum;
41  if (ArrayCursor == ArrayEnd)
42    WriteAndFlushBBTraceData ();
43}
44
45/* llvm_start_basic_block_tracing - This is the main entry point of the basic
46 * block tracing library.  It is responsible for setting up the atexit
47 * handler and allocating the trace buffer.
48 */
49int llvm_start_basic_block_tracing(int argc, const char **argv,
50                              unsigned *arrayStart, unsigned numElements) {
51  int Ret;
52  const unsigned BufferSize = 128 * 1024;
53  unsigned ArraySize;
54
55  Ret = save_arguments(argc, argv);
56
57  /* Allocate a buffer to contain BB tracing data */
58  ArraySize = BufferSize / sizeof (unsigned);
59  ArrayStart = malloc (ArraySize * sizeof (unsigned));
60  ArrayEnd = ArrayStart + ArraySize;
61  ArrayCursor = ArrayStart;
62
63  /* Set up the atexit handler. */
64  atexit (BBTraceAtExitHandler);
65
66  return Ret;
67}
68