runtime/libprofile/BasicBlockTracing.c

   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
  20 static 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  */
  25 static 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  */
  33 static void BBTraceAtExitHandler(void) {
  34   WriteAndFlushBBTraceData ();
  35   free (ArrayStart);
  36 }
  37
  38 /* llvm_trace_basic_block - called upon hitting a new basic block. */
  39 void 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  */
  49 int 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 }