[llvm] [llvm-exegesis]Allow clients to do their own snippet running error ha… (PR #74711)

[Clement Courbet via llvm-commits]

https://github.com/legrosbuffle updated https://github.com/llvm/llvm-project/pull/74711

>From cfdd67ac3c799c6ca2b7073e8b1353cbf1d29fd2 Mon Sep 17 00:00:00 2001
From: Clement Courbet <courbet at google.com>
Date: Thu, 7 Dec 2023 10:55:57 +0100
Subject: [PATCH] [llvm-exegesis]Allow clients to do their own snippet running
 error handling.

Returns an error *and* a benchmark rather than an error *or* a benchmark. This allows users
to have custom error handling while still being able to inspect the benchmark.

Apart from this small API change, this is an NFC.

This is an alternative to #74211.
---
 llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp | 16 ++++++----------
 llvm/tools/llvm-exegesis/lib/BenchmarkRunner.h   |  2 +-
 llvm/tools/llvm-exegesis/llvm-exegesis.cpp       | 14 ++++++++++++--
 3 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
index 8e242cdd1d905..6c34446e8d663 100644
--- a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
+++ b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
@@ -572,7 +572,7 @@ BenchmarkRunner::createFunctionExecutor(
   llvm_unreachable("ExecutionMode is outside expected range");
 }
 
-Expected<Benchmark> BenchmarkRunner::runConfiguration(
+std::pair<Error, Benchmark> BenchmarkRunner::runConfiguration(
     RunnableConfiguration &&RC,
     const std::optional<StringRef> &DumpFile) const {
   Benchmark &InstrBenchmark = RC.InstrBenchmark;
@@ -583,8 +583,7 @@ Expected<Benchmark> BenchmarkRunner::runConfiguration(
     auto ObjectFilePath =
         writeObjectFile(ObjectFile.getBinary()->getData(), *DumpFile);
     if (Error E = ObjectFilePath.takeError()) {
-      InstrBenchmark.Error = toString(std::move(E));
-      return std::move(InstrBenchmark);
+      return {std::move(E), std::move(InstrBenchmark)};
     }
     outs() << "Check generated assembly with: /usr/bin/objdump -d "
            << *ObjectFilePath << "\n";
@@ -592,20 +591,17 @@ Expected<Benchmark> BenchmarkRunner::runConfiguration(
 
   if (BenchmarkPhaseSelector < BenchmarkPhaseSelectorE::Measure) {
     InstrBenchmark.Error = "actual measurements skipped.";
-    return std::move(InstrBenchmark);
+    return {Error::success(), std::move(InstrBenchmark)};
   }
 
   Expected<std::unique_ptr<BenchmarkRunner::FunctionExecutor>> Executor =
       createFunctionExecutor(std::move(ObjectFile), RC.InstrBenchmark.Key);
   if (!Executor)
-    return Executor.takeError();
+    return {Executor.takeError(), std::move(InstrBenchmark)};
   auto NewMeasurements = runMeasurements(**Executor);
 
   if (Error E = NewMeasurements.takeError()) {
-    if (!E.isA<SnippetCrash>())
-      return std::move(E);
-    InstrBenchmark.Error = toString(std::move(E));
-    return std::move(InstrBenchmark);
+    return {std::move(E), std::move(InstrBenchmark)};
   }
   assert(InstrBenchmark.NumRepetitions > 0 && "invalid NumRepetitions");
   for (BenchmarkMeasure &BM : *NewMeasurements) {
@@ -618,7 +614,7 @@ Expected<Benchmark> BenchmarkRunner::runConfiguration(
   }
   InstrBenchmark.Measurements = std::move(*NewMeasurements);
 
-  return std::move(InstrBenchmark);
+  return {Error::success(), std::move(InstrBenchmark)};
 }
 
 Expected<std::string>
diff --git a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.h b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.h
index 24f2086289408..2c48d07e37ca9 100644
--- a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.h
+++ b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.h
@@ -65,7 +65,7 @@ class BenchmarkRunner {
                            unsigned NumRepetitions, unsigned LoopUnrollFactor,
                            const SnippetRepetitor &Repetitor) const;
 
-  Expected<Benchmark>
+  std::pair<Error, Benchmark>
   runConfiguration(RunnableConfiguration &&RC,
                    const std::optional<StringRef> &DumpFile) const;
 
diff --git a/llvm/tools/llvm-exegesis/llvm-exegesis.cpp b/llvm/tools/llvm-exegesis/llvm-exegesis.cpp
index 4e466303c9dbf..148891a18246f 100644
--- a/llvm/tools/llvm-exegesis/llvm-exegesis.cpp
+++ b/llvm/tools/llvm-exegesis/llvm-exegesis.cpp
@@ -410,8 +410,18 @@ static void runBenchmarkConfigurations(
       std::optional<StringRef> DumpFile;
       if (DumpObjectToDisk.getNumOccurrences())
         DumpFile = DumpObjectToDisk;
-      AllResults.emplace_back(
-          ExitOnErr(Runner.runConfiguration(std::move(RC), DumpFile)));
+      auto [Err, InstrBenchmark] =
+          Runner.runConfiguration(std::move(RC), DumpFile);
+      if (Err) {
+        // Errors from executing the snippets are fine.
+        // All other errors are a framework issue and should fail.
+        if (!Err.isA<SnippetCrash>()) {
+          llvm::errs() << "llvm-exegesis error: " << toString(std::move(Err));
+          exit(1);
+        }
+        InstrBenchmark.Error = toString(std::move(Err));
+      }
+      AllResults.push_back(std::move(InstrBenchmark));
     }
     Benchmark &Result = AllResults.front();