Add llvm-exegesis tool.

Summary:
[llvm-exegesis][RFC] Automatic Measurement of Instruction Latency/Uops

This is the code corresponding to the RFC "llvm-exegesis Automatic Measurement of Instruction Latency/Uops".

The RFC is available on the LLVM mailing lists as well as the following document
for easier reading:
https://docs.google.com/document/d/1QidaJMJUyQdRrFKD66vE1_N55whe0coQ3h1GpFzz27M/edit?usp=sharing

Subscribers: mgorny, gchatelet, orwant, llvm-commits

Differential Revision: https://reviews.llvm.org/D44519

llvm-svn: 329156

1 files changed, 85 insertions, 0 deletions

diff --git a/llvm/tools/llvm-exegesis/lib/BenchmarkResult.cpp b/llvm/tools/llvm-exegesis/lib/BenchmarkResult.cpp
new file mode 100644
index 00000000000..e9b8d29aaec
--- /dev/null
+++ b/llvm/tools/llvm-exegesis/lib/BenchmarkResult.cpp
@@ -0,0 +1,85 @@
+//===-- BenchmarkResult.cpp -------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "BenchmarkResult.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/FileOutputBuffer.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Format.h"
+#include "llvm/Support/raw_ostream.h"
+
+// Defining YAML traits for IO.
+namespace llvm {
+namespace yaml {
+
+// std::vector<exegesis::Measure> will be rendered as a list.
+template <> struct SequenceElementTraits<exegesis::BenchmarkMeasure> {
+  static const bool flow = false;
+};
+
+// exegesis::Measure is rendererd as a flow instead of a list.
+// e.g. { "key": "the key", "value": 0123 }
+template <> struct MappingTraits<exegesis::BenchmarkMeasure> {
+  static void mapping(IO &Io, exegesis::BenchmarkMeasure &Obj) {
+    Io.mapRequired("key", Obj.Key);
+    Io.mapRequired("value", Obj.Value);
+    Io.mapOptional("debug_string", Obj.DebugString);
+  }
+  static const bool flow = true;
+};
+
+template <> struct MappingTraits<exegesis::AsmTemplate> {
+  static void mapping(IO &Io, exegesis::AsmTemplate &Obj) {
+    Io.mapRequired("name", Obj.Name);
+  }
+};
+
+template <> struct MappingTraits<exegesis::InstructionBenchmark> {
+  static void mapping(IO &Io, exegesis::InstructionBenchmark &Obj) {
+    Io.mapRequired("asm_template", Obj.AsmTmpl);
+    Io.mapRequired("cpu_name", Obj.CpuName);
+    Io.mapRequired("llvm_triple", Obj.LLVMTriple);
+    Io.mapRequired("num_repetitions", Obj.NumRepetitions);
+    Io.mapRequired("measurements", Obj.Measurements);
+    Io.mapRequired("error", Obj.Error);
+  }
+};
+
+} // namespace yaml
+} // namespace llvm
+
+namespace exegesis {
+
+InstructionBenchmark
+InstructionBenchmark::readYamlOrDie(llvm::StringRef Filename) {
+  std::unique_ptr<llvm::MemoryBuffer> MemBuffer = llvm::cantFail(
+      llvm::errorOrToExpected(llvm::MemoryBuffer::getFile(Filename)));
+  llvm::yaml::Input Yin(*MemBuffer);
+  InstructionBenchmark Benchmark;
+  Yin >> Benchmark;
+  return Benchmark;
+}
+
+void InstructionBenchmark::writeYamlOrDie(const llvm::StringRef Filename) {
+  if (Filename == "-") {
+    llvm::yaml::Output Yout(llvm::outs());
+    Yout << *this;
+  } else {
+    llvm::SmallString<1024> Buffer;
+    llvm::raw_svector_ostream Ostr(Buffer);
+    llvm::yaml::Output Yout(Ostr);
+    Yout << *this;
+    std::unique_ptr<llvm::FileOutputBuffer> File =
+        llvm::cantFail(llvm::FileOutputBuffer::create(Filename, Buffer.size()));
+    memcpy(File->getBufferStart(), Buffer.data(), Buffer.size());
+    llvm::cantFail(File->commit());
+  }
+}
+
+} // namespace exegesis