InstructionTables.cpp revision 360784 
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
19namespace llvm {
20namespace mca {
21
22Error 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<const 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(
34        Masks.begin(), std::find(Masks.begin(), Masks.end(), Resource.first));
35    const MCProcResourceDesc &ProcResource = *SM.getProcResource(Index);
36    unsigned NumUnits = ProcResource.NumUnits;
37    if (!ProcResource.SubUnitsIdxBegin) {
38      // The number of cycles consumed by each unit.
39      for (unsigned I = 0, E = NumUnits; I < E; ++I) {
40        ResourceRef ResourceUnit = std::make_pair(Index, 1U << I);
41        UsedResources.emplace_back(
42            std::make_pair(ResourceUnit, ResourceCycles(Cycles, NumUnits)));
43      }
44      continue;
45    }
46
47    // This is a group. Obtain the set of resources contained in this
48    // group. Some of these resources may implement multiple units.
49    // Uniformly distribute Cycles across all of the units.
50    for (unsigned I1 = 0; I1 < NumUnits; ++I1) {
51      unsigned SubUnitIdx = ProcResource.SubUnitsIdxBegin[I1];
52      const MCProcResourceDesc &SubUnit = *SM.getProcResource(SubUnitIdx);
53      // Compute the number of cycles consumed by each resource unit.
54      for (unsigned I2 = 0, E2 = SubUnit.NumUnits; I2 < E2; ++I2) {
55        ResourceRef ResourceUnit = std::make_pair(SubUnitIdx, 1U << I2);
56        UsedResources.emplace_back(std::make_pair(
57            ResourceUnit, ResourceCycles(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
70