benchmarks/bench-branch-masm.cc

// Copyright 2015, ARM Limited
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#include "vixl/globals.h"

#include "vixl/a64/macro-assembler-a64.h"
#include "vixl/a64/instructions-a64.h"

using namespace vixl;

static const int kDefaultIterationCount = 100000;

// This program focuses on emitting branch instructions targeting a label bound
// very closely. Here the MacroAssembler is used. This exercises label binding
// and patching mechanisms, as well as the veneer resolving mechanisms for
// branches not requiring veneers.
int main(int argc, char* argv[]) {
  int iterations = 0;

  switch (argc) {
    case 1:
      iterations = kDefaultIterationCount;
      break;
    case 2:
      iterations = atoi(argv[1]);
      break;
    default:
      printf("Usage: %s [#iterations]\n", argv[0]);
      exit(1);
  }

  const int buffer_size = 256 * KBytes;
  const int instructions_per_iteration = 4;
  const int max_buffer_iterations =
      buffer_size / (instructions_per_iteration * kInstructionSize);

  MacroAssembler masm(buffer_size);

#define __ masm.

  for (int i = 0; i < iterations;) {
    masm.Reset();
    for (int j = 0; (j < max_buffer_iterations) && (i < iterations); ++j, ++i) {
      Label target;
      __ B(&target);
      __ B(eq, &target);
      __ Cbz(x2, &target);
      __ Tbz(x3, 2, &target);
      __ Bind(&target);
    }
  }

  masm.FinalizeCode();

  return 0;
}