benchmarks/aarch64/bench-branch-masm.cc

// Copyright 2019, VIXL authors
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#include "bench-utils.h"
#include "globals-vixl.h"

#include "aarch64/instructions-aarch64.h"
#include "aarch64/macro-assembler-aarch64.h"

using namespace vixl;
using namespace vixl::aarch64;

// 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[]) {
  BenchCLI cli(argc, argv);
  if (cli.ShouldExitEarly()) return cli.GetExitCode();

  const size_t buffer_size = 256 * KBytes;
  const size_t instructions_per_iteration = 4;
  const size_t max_buffer_iterations =
      buffer_size / (instructions_per_iteration * kInstructionSize);
  MacroAssembler masm(buffer_size);

  BenchTimer timer;

  size_t iterations = 0;
  do {
    masm.Reset();
    for (size_t i = 0; i < max_buffer_iterations; ++i) {
      Label target;
      masm.B(&target);
      masm.B(eq, &target);
      masm.Cbz(x2, &target);
      masm.Tbz(x3, 2, &target);
      masm.Bind(&target);
    }
    masm.FinalizeCode();
    iterations++;
  } while (!timer.HasRunFor(cli.GetRunTimeInSeconds()));

  cli.PrintResults(iterations, timer.GetElapsedSeconds());
  return cli.GetExitCode();
}