1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
|
//===-- BenchmarkRunner.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
//
//===----------------------------------------------------------------------===//
#include <array>
#include <string>
#include "Assembler.h"
#include "BenchmarkRunner.h"
#include "MCInstrDescView.h"
#include "PerfHelper.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Support/CrashRecoveryContext.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Program.h"
namespace llvm {
namespace exegesis {
BenchmarkFailure::BenchmarkFailure(const llvm::Twine &S)
: llvm::StringError(S, llvm::inconvertibleErrorCode()) {}
BenchmarkRunner::BenchmarkRunner(const LLVMState &State,
InstructionBenchmark::ModeE Mode)
: State(State), Mode(Mode), Scratch(llvm::make_unique<ScratchSpace>()) {}
BenchmarkRunner::~BenchmarkRunner() = default;
// Repeat the snippet until there are at least MinInstructions in the resulting
// code.
static std::vector<llvm::MCInst>
GenerateInstructions(const BenchmarkCode &BC, const size_t MinInstructions) {
if (BC.Instructions.empty())
return {};
std::vector<llvm::MCInst> Code = BC.Instructions;
for (int I = 0; Code.size() < MinInstructions; ++I)
Code.push_back(BC.Instructions[I % BC.Instructions.size()]);
return Code;
}
namespace {
class FunctionExecutorImpl : public BenchmarkRunner::FunctionExecutor {
public:
FunctionExecutorImpl(const LLVMState &State,
llvm::object::OwningBinary<llvm::object::ObjectFile> Obj,
BenchmarkRunner::ScratchSpace *Scratch)
: Function(State.createTargetMachine(), std::move(Obj)),
Scratch(Scratch) {}
private:
llvm::Expected<int64_t> runAndMeasure(const char *Counters) const override {
// We sum counts when there are several counters for a single ProcRes
// (e.g. P23 on SandyBridge).
int64_t CounterValue = 0;
llvm::SmallVector<llvm::StringRef, 2> CounterNames;
llvm::StringRef(Counters).split(CounterNames, '+');
char *const ScratchPtr = Scratch->ptr();
for (auto &CounterName : CounterNames) {
CounterName = CounterName.trim();
pfm::PerfEvent PerfEvent(CounterName);
if (!PerfEvent.valid())
llvm::report_fatal_error(llvm::Twine("invalid perf event '")
.concat(CounterName)
.concat("'"));
pfm::Counter Counter(PerfEvent);
Scratch->clear();
{
llvm::CrashRecoveryContext CRC;
llvm::CrashRecoveryContext::Enable();
const bool Crashed = !CRC.RunSafely([this, &Counter, ScratchPtr]() {
Counter.start();
this->Function(ScratchPtr);
Counter.stop();
});
llvm::CrashRecoveryContext::Disable();
// FIXME: Better diagnosis.
if (Crashed)
return llvm::make_error<BenchmarkFailure>(
"snippet crashed while running");
}
CounterValue += Counter.read();
}
return CounterValue;
}
const ExecutableFunction Function;
BenchmarkRunner::ScratchSpace *const Scratch;
};
} // namespace
InstructionBenchmark
BenchmarkRunner::runConfiguration(const BenchmarkCode &BC,
unsigned NumRepetitions,
bool DumpObjectToDisk) const {
InstructionBenchmark InstrBenchmark;
InstrBenchmark.Mode = Mode;
InstrBenchmark.CpuName = State.getTargetMachine().getTargetCPU();
InstrBenchmark.LLVMTriple =
State.getTargetMachine().getTargetTriple().normalize();
InstrBenchmark.NumRepetitions = NumRepetitions;
InstrBenchmark.Info = BC.Info;
const std::vector<llvm::MCInst> &Instructions = BC.Instructions;
InstrBenchmark.Key.Instructions = Instructions;
InstrBenchmark.Key.RegisterInitialValues = BC.RegisterInitialValues;
// Assemble at least kMinInstructionsForSnippet instructions by repeating the
// snippet for debug/analysis. This is so that the user clearly understands
// that the inside instructions are repeated.
constexpr const int kMinInstructionsForSnippet = 16;
{
llvm::SmallString<0> Buffer;
llvm::raw_svector_ostream OS(Buffer);
assembleToStream(State.getExegesisTarget(), State.createTargetMachine(),
BC.LiveIns, BC.RegisterInitialValues,
GenerateInstructions(BC, kMinInstructionsForSnippet), OS);
const ExecutableFunction EF(State.createTargetMachine(),
getObjectFromBuffer(OS.str()));
const auto FnBytes = EF.getFunctionBytes();
InstrBenchmark.AssembledSnippet.assign(FnBytes.begin(), FnBytes.end());
}
// Assemble NumRepetitions instructions repetitions of the snippet for
// measurements.
const auto Code = GenerateInstructions(BC, InstrBenchmark.NumRepetitions);
llvm::object::OwningBinary<llvm::object::ObjectFile> ObjectFile;
if (DumpObjectToDisk) {
auto ObjectFilePath = writeObjectFile(BC, Code);
if (llvm::Error E = ObjectFilePath.takeError()) {
InstrBenchmark.Error = llvm::toString(std::move(E));
return InstrBenchmark;
}
llvm::outs() << "Check generated assembly with: /usr/bin/objdump -d "
<< *ObjectFilePath << "\n";
ObjectFile = getObjectFromFile(*ObjectFilePath);
} else {
llvm::SmallString<0> Buffer;
llvm::raw_svector_ostream OS(Buffer);
assembleToStream(State.getExegesisTarget(), State.createTargetMachine(),
BC.LiveIns, BC.RegisterInitialValues, Code, OS);
ObjectFile = getObjectFromBuffer(OS.str());
}
const FunctionExecutorImpl Executor(State, std::move(ObjectFile),
Scratch.get());
auto Measurements = runMeasurements(Executor);
if (llvm::Error E = Measurements.takeError()) {
InstrBenchmark.Error = llvm::toString(std::move(E));
return InstrBenchmark;
}
InstrBenchmark.Measurements = std::move(*Measurements);
assert(InstrBenchmark.NumRepetitions > 0 && "invalid NumRepetitions");
for (BenchmarkMeasure &BM : InstrBenchmark.Measurements) {
// Scale the measurements by instruction.
BM.PerInstructionValue /= InstrBenchmark.NumRepetitions;
// Scale the measurements by snippet.
BM.PerSnippetValue *= static_cast<double>(BC.Instructions.size()) /
InstrBenchmark.NumRepetitions;
}
return InstrBenchmark;
}
llvm::Expected<std::string>
BenchmarkRunner::writeObjectFile(const BenchmarkCode &BC,
llvm::ArrayRef<llvm::MCInst> Code) const {
int ResultFD = 0;
llvm::SmallString<256> ResultPath;
if (llvm::Error E = llvm::errorCodeToError(llvm::sys::fs::createTemporaryFile(
"snippet", "o", ResultFD, ResultPath)))
return std::move(E);
llvm::raw_fd_ostream OFS(ResultFD, true /*ShouldClose*/);
assembleToStream(State.getExegesisTarget(), State.createTargetMachine(),
BC.LiveIns, BC.RegisterInitialValues, Code, OFS);
return ResultPath.str();
}
BenchmarkRunner::FunctionExecutor::~FunctionExecutor() {}
} // namespace exegesis
} // namespace llvm
|
