tools/llvm-mca/Views/DispatchStatistics.h

   1 //===--------------------- DispatchStatistics.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 /// \file
   9 ///
  10 /// This file implements a view that prints a few statistics related to the
  11 /// dispatch logic. It collects and analyzes instruction dispatch events as
  12 /// well as static/dynamic dispatch stall events.
  13 ///
  14 /// Example:
  15 /// ========
  16 ///
  17 /// Dynamic Dispatch Stall Cycles:
  18 /// RAT     - Register unavailable:                      0
  19 /// RCU     - Retire tokens unavailable:                 0
  20 /// SCHEDQ  - Scheduler full:                            42
  21 /// LQ      - Load queue full:                           0
  22 /// SQ      - Store queue full:                          0
  23 /// GROUP   - Static restrictions on the dispatch group: 0
  24 ///
  25 ///
  26 /// Dispatch Logic - number of cycles where we saw N micro opcodes dispatched:
  27 /// [# dispatched], [# cycles]
  28 ///  0,              15  (11.5%)
  29 ///  2,              4  (3.1%)
  30 ///
  31 //===----------------------------------------------------------------------===//
  32
  33 #ifndef LLVM_TOOLS_LLVM_MCA_DISPATCHVIEW_H
  34 #define LLVM_TOOLS_LLVM_MCA_DISPATCHVIEW_H
  35
  36 #include "Views/View.h"
  37 #include "llvm/ADT/SmallVector.h"
  38 #include "llvm/MC/MCSubtargetInfo.h"
  39 #include <map>
  40
  41 namespace llvm {
  42 namespace mca {
  43
  44 class DispatchStatistics : public View {
  45   unsigned NumDispatched;
  46   unsigned NumCycles;
  47
  48   // Counts dispatch stall events caused by unavailability of resources.  There
  49   // is one counter for every generic stall kind (see class HWStallEvent).
  50   llvm::SmallVector<unsigned, 8> HWStalls;
  51
  52   using Histogram = std::map<unsigned, unsigned>;
  53   Histogram DispatchGroupSizePerCycle;
  54
  55   void updateHistograms() {
  56     DispatchGroupSizePerCycle[NumDispatched]++;
  57     NumDispatched = 0;
  58   }
  59
  60   void printDispatchHistogram(llvm::raw_ostream &OS) const;
  61
  62   void printDispatchStalls(llvm::raw_ostream &OS) const;
  63
  64 public:
  65   DispatchStatistics()
  66       : NumDispatched(0), NumCycles(0),
  67         HWStalls(HWStallEvent::LastGenericEvent) {}
  68
  69   void onEvent(const HWStallEvent &Event) override;
  70
  71   void onEvent(const HWInstructionEvent &Event) override;
  72
  73   void onCycleBegin() override { NumCycles++; }
  74
  75   void onCycleEnd() override { updateHistograms(); }
  76
  77   void printView(llvm::raw_ostream &OS) const override {
  78     printDispatchStalls(OS);
  79     printDispatchHistogram(OS);
  80   }
  81 };
  82 } // namespace mca
  83 } // namespace llvm
  84
  85 #endif