[llvm-exegesis] Fix unhandled error.

[gchatelet]

Summary

Fixing an unhandled error when calling writeYaml.

[gchatelet]

Removed LLVM_NODISCARD from InstructionBenchmark IO functions since llvm::Error is already marked as LLVM_NODISCARD.

[gchatelet]

Removing unnecessary header.

[courbet]

Too bad clang does not catch this in loops.

[RKSimon]

Thanks - this fixes PR37759

tools/llvm-exegesis/lib/BenchmarkResult.h

 
 #ifndef LLVM_TOOLS_LLVM_EXEGESIS_BENCHMARKRESULT_H
 #define LLVM_TOOLS_LLVM_EXEGESIS_BENCHMARKRESULT_H
 
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/MC/MCInst.h"
 #include "llvm/MC/MCInstBuilder.h"
+#include "llvm/Support/Compiler.h"
 #include "llvm/Support/YAMLTraits.h"
 #include <limits>
 #include <string>
 #include <unordered_map>
 #include <vector>
 
 namespace exegesis {
 
struct InstructionBenchmark {
   std::string CpuName;
   std::string LLVMTriple;
   int NumRepetitions = 0;
   std::vector<BenchmarkMeasure> Measurements;
   std::string Error;
   std::string Info;
 
   // Read functions.
-  static llvm::Expected<InstructionBenchmark>
+  LLVM_NODISCARD static llvm::Expected<InstructionBenchmark>
   readYaml(const BenchmarkResultContext &Context, llvm::StringRef Filename);
 
-  static llvm::Expected<std::vector<InstructionBenchmark>>
+  LLVM_NODISCARD static llvm::Expected<std::vector<InstructionBenchmark>>
   readYamls(const BenchmarkResultContext &Context, llvm::StringRef Filename);
 
   void readYamlFrom(const BenchmarkResultContext &Context,
                     llvm::StringRef InputContent);
 
   // Write functions, non-const because of YAML traits.
   void writeYamlTo(const BenchmarkResultContext &Context, llvm::raw_ostream &S);
 
-  llvm::Error writeYaml(const BenchmarkResultContext &Context,
+  LLVM_NODISCARD llvm::Error writeYaml(const BenchmarkResultContext &Context,
                                        const llvm::StringRef Filename);
 };
 
 //------------------------------------------------------------------------------
 // Utilities to work with Benchmark measures.
 
 // A class that measures stats over benchmark measures.
 class BenchmarkMeasureStats {
 public:

tools/llvm-exegesis/llvm-exegesis.cpp

void benchmarkMain() {
   // Write to standard output if file is not set.
   if (BenchmarkFile.empty())
     BenchmarkFile = "-";
 
   const BenchmarkResultContext Context = getBenchmarkResultContext(State);
   std::vector<InstructionBenchmark> Results = ExitOnErr(Runner->run(
       GetOpcodeOrDie(State.getInstrInfo()), Filter, NumRepetitions));
   for (InstructionBenchmark &Result : Results)
-    Result.writeYaml(Context, BenchmarkFile);
+    ExitOnErr(Result.writeYaml(Context, BenchmarkFile));
 
   exegesis::pfm::pfmTerminate();
 }
 
 // Prints the results of running analysis pass `Pass` to file `OutputFilename`
 // if OutputFilename is non-empty.
 template <typename Pass>
 static void maybeRunAnalysis(const Analysis &Analyzer, const std::string &Name,