bench-branch.cc revision 07d1aa5b941ace15deb01e5df2c79e677039c4ae 
1// Copyright 2015, VIXL authors
2// All rights reserved.
3//
4// Redistribution and use in source and binary forms, with or without
5// modification, are permitted provided that the following conditions are met:
6//
7//   * Redistributions of source code must retain the above copyright notice,
8//     this list of conditions and the following disclaimer.
9//   * Redistributions in binary form must reproduce the above copyright notice,
10//     this list of conditions and the following disclaimer in the documentation
11//     and/or other materials provided with the distribution.
12//   * Neither the name of ARM Limited nor the names of its contributors may be
13//     used to endorse or promote products derived from this software without
14//     specific prior written permission.
15//
16// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND
17// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
20// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
22// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
23// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
25// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26
27#include <sys/time.h>
28#include "globals-vixl.h"
29
30#include "aarch64/instructions-aarch64.h"
31#include "aarch64/macro-assembler-aarch64.h"
32
33using namespace vixl;
34using namespace vixl::aarch64;
35
36static const int kDefaultInstructionCount = 100000;
37
38// This program focuses on emitting branch instructions.
39//
40// This code will emit a given number of branch immediate to the next
41// instructions in a fixed size buffer, looping over the buffer if necessary.
42// This code therefore focuses on Emit and label binding/patching.
43int main(int argc, char* argv[]) {
44  int instructions = 0;
45
46  switch (argc) {
47    case 1:
48      instructions = kDefaultInstructionCount;
49      break;
50    case 2:
51      instructions = atoi(argv[1]);
52      break;
53    default:
54      printf("Usage: %s [#instructions]\n", argv[0]);
55      exit(1);
56  }
57
58  const int buffer_size = 256 * KBytes;
59  const int buffer_instruction_count = buffer_size / kInstructionSize;
60  timeval start;
61  gettimeofday(&start, NULL);
62  MacroAssembler masm(buffer_size);
63
64#define __ masm.
65  // We emit a branch to the next instruction.
66
67  int rounds = instructions / buffer_instruction_count;
68  for (int i = 0; i < rounds; ++i) {
69    {
70      ExactAssemblyScope scope(&masm, buffer_size);
71      for (int j = 0; j < buffer_instruction_count; ++j) {
72        Label target;
73        __ b(&target);
74        __ bind(&target);
75      }
76    }
77    masm.Reset();
78  }
79
80  int remaining = instructions % buffer_instruction_count;
81  {
82    ExactAssemblyScope scope(&masm, remaining * kInstructionSize);
83    for (int i = 0; i < remaining; ++i) {
84      Label target;
85      __ b(&target);
86      __ bind(&target);
87    }
88  }
89
90  masm.FinalizeCode();
91  timeval end;
92  gettimeofday(&end, NULL);
93  double delta = (end.tv_sec - start.tv_sec) +
94                 static_cast<double>(end.tv_usec - start.tv_usec) / 1000000;
95  printf("A64: time for %d instructions: %gs\n", instructions, delta);
96
97  return 0;
98}
99