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//===--------------------- BottleneckAnalysis.cpp ---------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
/// \file
///
/// This file implements the functionalities used by the BottleneckAnalysis
/// to report bottleneck info.
///
//===----------------------------------------------------------------------===//
#include "Views/BottleneckAnalysis.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/MCA/Support.h"
#include "llvm/Support/Format.h"
namespace llvm {
namespace mca {
#define DEBUG_TYPE "llvm-mca"
BottleneckAnalysis::BottleneckAnalysis(const MCSchedModel &Model)
: SM(Model), TotalCycles(0), BPI({0, 0, 0, 0, 0}),
ResourcePressureDistribution(Model.getNumProcResourceKinds(), 0),
ProcResourceMasks(Model.getNumProcResourceKinds()),
ResIdx2ProcResID(Model.getNumProcResourceKinds(), 0),
PressureIncreasedBecauseOfResources(false),
PressureIncreasedBecauseOfDataDependencies(false),
SeenStallCycles(false) {
computeProcResourceMasks(SM, ProcResourceMasks);
for (unsigned I = 1, E = SM.getNumProcResourceKinds(); I < E; ++I) {
unsigned Index = getResourceStateIndex(ProcResourceMasks[I]);
ResIdx2ProcResID[Index] = I;
}
}
void BottleneckAnalysis::onEvent(const HWPressureEvent &Event) {
assert(Event.Reason != HWPressureEvent::INVALID &&
"Unexpected invalid event!");
switch (Event.Reason) {
default:
break;
case HWPressureEvent::RESOURCES: {
PressureIncreasedBecauseOfResources = true;
++BPI.ResourcePressureCycles;
uint64_t ResourceMask = Event.ResourceMask;
while (ResourceMask) {
uint64_t Current = ResourceMask & (-ResourceMask);
unsigned Index = getResourceStateIndex(Current);
unsigned ProcResID = ResIdx2ProcResID[Index];
const MCProcResourceDesc &PRDesc = *SM.getProcResource(ProcResID);
if (!PRDesc.SubUnitsIdxBegin) {
ResourcePressureDistribution[Index]++;
ResourceMask ^= Current;
continue;
}
for (unsigned I = 0, E = PRDesc.NumUnits; I < E; ++I) {
unsigned OtherProcResID = PRDesc.SubUnitsIdxBegin[I];
unsigned OtherMask = ProcResourceMasks[OtherProcResID];
ResourcePressureDistribution[getResourceStateIndex(OtherMask)]++;
}
ResourceMask ^= Current;
}
break;
}
case HWPressureEvent::REGISTER_DEPS:
PressureIncreasedBecauseOfDataDependencies = true;
++BPI.RegisterDependencyCycles;
break;
case HWPressureEvent::MEMORY_DEPS:
PressureIncreasedBecauseOfDataDependencies = true;
++BPI.MemoryDependencyCycles;
break;
}
}
void BottleneckAnalysis::printBottleneckHints(raw_ostream &OS) const {
if (!SeenStallCycles || !BPI.PressureIncreaseCycles) {
OS << "\nNo resource or data dependency bottlenecks discovered.\n";
return;
}
double PressurePerCycle =
(double)BPI.PressureIncreaseCycles * 100 / TotalCycles;
double ResourcePressurePerCycle =
(double)BPI.ResourcePressureCycles * 100 / TotalCycles;
double DDPerCycle = (double)BPI.DataDependencyCycles * 100 / TotalCycles;
double RegDepPressurePerCycle =
(double)BPI.RegisterDependencyCycles * 100 / TotalCycles;
double MemDepPressurePerCycle =
(double)BPI.MemoryDependencyCycles * 100 / TotalCycles;
OS << "\nCycles with backend pressure increase [ "
<< format("%.2f", floor((PressurePerCycle * 100) + 0.5) / 100) << "% ]";
OS << "\nThroughput Bottlenecks: "
<< "\n Resource Pressure [ "
<< format("%.2f", floor((ResourcePressurePerCycle * 100) + 0.5) / 100)
<< "% ]";
if (BPI.PressureIncreaseCycles) {
for (unsigned I = 0, E = ResourcePressureDistribution.size(); I < E; ++I) {
if (ResourcePressureDistribution[I]) {
double Frequency =
(double)ResourcePressureDistribution[I] * 100 / TotalCycles;
unsigned Index = ResIdx2ProcResID[getResourceStateIndex(1ULL << I)];
const MCProcResourceDesc &PRDesc = *SM.getProcResource(Index);
OS << "\n - " << PRDesc.Name << " [ "
<< format("%.2f", floor((Frequency * 100) + 0.5) / 100) << "% ]";
}
}
}
OS << "\n Data Dependencies: [ "
<< format("%.2f", floor((DDPerCycle * 100) + 0.5) / 100) << "% ]";
OS << "\n - Register Dependencies [ "
<< format("%.2f", floor((RegDepPressurePerCycle * 100) + 0.5) / 100)
<< "% ]";
OS << "\n - Memory Dependencies [ "
<< format("%.2f", floor((MemDepPressurePerCycle * 100) + 0.5) / 100)
<< "% ]\n\n";
}
void BottleneckAnalysis::printView(raw_ostream &OS) const {
std::string Buffer;
raw_string_ostream TempStream(Buffer);
printBottleneckHints(TempStream);
TempStream.flush();
OS << Buffer;
}
} // namespace mca.
} // namespace llvm
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