llvm/tools/llvm-exegesis/lib/X86/X86Counter.h

   1 //===-- X86Counter.h --------------------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 ///
   9 /// \file
  10 /// Perf counter that reads the LBRs for measuring the benchmarked block's
  11 /// throughput.
  12 ///
  13 /// More info at: https://lwn.net/Articles/680985
  14 //===----------------------------------------------------------------------===//
  15 #ifndef LLVM_TOOLS_LLVM_EXEGESIS_LIB_X86_X86COUNTER_H
  16 #define LLVM_TOOLS_LLVM_EXEGESIS_LIB_X86_X86COUNTER_H
  17
  18 #include "../PerfHelper.h"
  19 #include "llvm/Support/Error.h"
  20
  21 // FIXME: Use appropriate wrappers for poll.h and mman.h
  22 // to support Windows and remove this linux-only guard.
  23 #if defined(__linux__) && defined(HAVE_LIBPFM) &&                              \
  24     defined(LIBPFM_HAS_FIELD_CYCLES)
  25
  26 namespace llvm {
  27 namespace exegesis {
  28
  29 class X86LbrPerfEvent : public pfm::PerfEvent {
  30 public:
  31   X86LbrPerfEvent(unsigned SamplingPeriod);
  32 };
  33
  34 class X86LbrCounter : public pfm::Counter {
  35 public:
  36   static llvm::Error checkLbrSupport();
  37
  38   explicit X86LbrCounter(pfm::PerfEvent &&Event);
  39
  40   virtual ~X86LbrCounter();
  41
  42   void start() override;
  43
  44   llvm::Expected<llvm::SmallVector<int64_t, 4>>
  45   readOrError(StringRef FunctionBytes) const override;
  46
  47 private:
  48   llvm::Expected<llvm::SmallVector<int64_t, 4>>
  49   doReadCounter(const void *From, const void *To) const;
  50
  51   void *MMappedBuffer = nullptr;
  52 };
  53
  54 } // namespace exegesis
  55 } // namespace llvm
  56
  57 #endif // defined(__linux__) && defined(HAVE_LIBPFM) &&
  58        // defined(LIBPFM_HAS_FIELD_CYCLES)
  59
  60 #endif // LLVM_TOOLS_LLVM_EXEGESIS_LIB_X86_X86COUNTER_H