[llvm-reduce] make llvm-reduce save the best reduction it has when it crashes

This helps with both debugging llvm-reduce and sometimes getting usefull result even if llvm-reduce crashes

Reviewed By: lebedev.ri

Differential Revision: https://reviews.llvm.org/D85996

1 files changed, 18 insertions, 15 deletions

diff --git a/llvm/tools/llvm-reduce/llvm-reduce.cpp b/llvm/tools/llvm-reduce/llvm-reduce.cpp
index 9dd8aa4..376826b 100644
--- a/llvm/tools/llvm-reduce/llvm-reduce.cpp
+++ b/llvm/tools/llvm-reduce/llvm-reduce.cpp
@@ -80,6 +80,22 @@ static std::unique_ptr<Module> parseInputFile(StringRef Filename,
   return Result;
 }
 
+void writeOutput(Module *M, StringRef Message) {
+  if (ReplaceInput) // In-place
+    OutputFilename = InputFilename.c_str();
+  else if (OutputFilename.empty() || OutputFilename == "-")
+    OutputFilename = "reduced.ll";
+
+  std::error_code EC;
+  raw_fd_ostream Out(OutputFilename, EC);
+  if (EC) {
+    errs() << "Error opening output file: " << EC.message() << "!\n";
+    exit(1);
+  }
+  M->print(Out, /*AnnotationWriter=*/nullptr);
+  errs() << Message << OutputFilename << "\n";
+}
+
 int main(int argc, char **argv) {
   InitLLVM X(argc, argv);
 
@@ -102,21 +118,8 @@ int main(int argc, char **argv) {
     // Print reduced file to STDOUT
     if (OutputFilename == "-")
       Tester.getProgram()->print(outs(), nullptr);
-    else {
-      if (ReplaceInput) // In-place
-        OutputFilename = InputFilename.c_str();
-      else if (OutputFilename.empty())
-        OutputFilename = "reduced.ll";
-
-      std::error_code EC;
-      raw_fd_ostream Out(OutputFilename, EC);
-      if (EC) {
-        errs() << "Error opening output file: " << EC.message() << "!\n";
-        exit(1);
-      }
-      Tester.getProgram()->print(Out, /*AnnotationWriter=*/nullptr);
-      errs() << "\nDone reducing! Reduced testcase: " << OutputFilename << "\n";
-    }
+    else
+      writeOutput(Tester.getProgram(), "\nDone reducing! Reduced testcase: ");
   }
 
   return 0;