llvm/lib/MCA/Stages/InstructionTables.cpp

   1 //===--------------------- InstructionTables.cpp ----------------*- 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 the method InstructionTables::execute().
  11 /// Method execute() prints a theoretical resource pressure distribution based
  12 /// on the information available in the scheduling model, and without running
  13 /// the pipeline.
  14 ///
  15 //===----------------------------------------------------------------------===//
  16
  17 #include "llvm/MCA/Stages/InstructionTables.h"
  18
  19 namespace llvm {
  20 namespace mca {
  21
  22 Error InstructionTables::execute(InstRef &IR) {
  23   const InstrDesc &Desc = IR.getInstruction()->getDesc();
  24   UsedResources.clear();
  25
  26   // Identify the resources consumed by this instruction.
  27   for (const std::pair<uint64_t, ResourceUsage> &Resource :
  28        Desc.Resources) {
  29     // Skip zero-cycle resources (i.e., unused resources).
  30     if (!Resource.second.size())
  31       continue;
  32     unsigned Cycles = Resource.second.size();
  33     unsigned Index = std::distance(Masks.begin(), find(Masks, Resource.first));
  34     const MCProcResourceDesc &ProcResource = *SM.getProcResource(Index);
  35     unsigned NumUnits = ProcResource.NumUnits;
  36     if (!ProcResource.SubUnitsIdxBegin) {
  37       // The number of cycles consumed by each unit.
  38       for (unsigned I = 0, E = NumUnits; I < E; ++I) {
  39         ResourceRef ResourceUnit = std::make_pair(Index, 1U << I);
  40         UsedResources.emplace_back(
  41             std::make_pair(ResourceUnit, ReleaseAtCycles(Cycles, NumUnits)));
  42       }
  43       continue;
  44     }
  45
  46     // This is a group. Obtain the set of resources contained in this
  47     // group. Some of these resources may implement multiple units.
  48     // Uniformly distribute Cycles across all of the units.
  49     for (unsigned I1 = 0; I1 < NumUnits; ++I1) {
  50       unsigned SubUnitIdx = ProcResource.SubUnitsIdxBegin[I1];
  51       const MCProcResourceDesc &SubUnit = *SM.getProcResource(SubUnitIdx);
  52       // Compute the number of cycles consumed by each resource unit.
  53       for (unsigned I2 = 0, E2 = SubUnit.NumUnits; I2 < E2; ++I2) {
  54         ResourceRef ResourceUnit = std::make_pair(SubUnitIdx, 1U << I2);
  55         UsedResources.emplace_back(std::make_pair(
  56             ResourceUnit,
  57             ReleaseAtCycles(Cycles, NumUnits * SubUnit.NumUnits)));
  58       }
  59     }
  60   }
  61
  62   // Send a fake instruction issued event to all the views.
  63   HWInstructionIssuedEvent Event(IR, UsedResources);
  64   notifyEvent<HWInstructionIssuedEvent>(Event);
  65   return ErrorSuccess();
  66 }
  67
  68 } // namespace mca
  69 } // namespace llvm