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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  */
WriteAndFlushBBTraceData()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  */
BBTraceAtExitHandler(void)33 static void BBTraceAtExitHandler(void) {
34   WriteAndFlushBBTraceData ();
35   free (ArrayStart);
36 }
37 
38 /* llvm_trace_basic_block - called upon hitting a new basic block. */
llvm_trace_basic_block(unsigned BBNum)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  */
llvm_start_basic_block_tracing(int argc,const char ** argv,unsigned * arrayStart,unsigned numElements)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 }
68