[PATCH] D85996: [llvm-reduce] make llvm-reduce save the best reduction it has when it crashes

[Tyker via Phabricator via llvm-commits]

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


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D85996

Files:
  llvm/tools/llvm-reduce/deltas/Delta.cpp
  llvm/tools/llvm-reduce/llvm-reduce.cpp


Index: llvm/tools/llvm-reduce/llvm-reduce.cpp
===================================================================
--- llvm/tools/llvm-reduce/llvm-reduce.cpp
+++ llvm/tools/llvm-reduce/llvm-reduce.cpp
@@ -21,6 +21,7 @@
 #include "llvm/IRReader/IRReader.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/InitLLVM.h"
+#include "llvm/Support/Signals.h"
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/raw_ostream.h"
 #include <system_error>
@@ -80,6 +81,22 @@
   return Result;
 }
 
+/// This variable is mark volatile because it is accessed by a signal handler.
+Module *volatile LastIntersting = nullptr;
+
+static void onCrashHandler(void *) {
+  StringRef Path = "last-interssting.ll";
+
+  std::error_code EC;
+  raw_fd_ostream Out(Path, EC);
+  if (EC) {
+    errs() << "Error opening output file: " << EC.message() << "!\n";
+    exit(1);
+  }
+  LastIntersting->print(Out, /*AnnotationWriter=*/nullptr);
+  errs() << "\n Saved last intersting Module to " << Path << "\n";
+}
+
 int main(int argc, char **argv) {
   InitLLVM X(argc, argv);
 
@@ -88,6 +105,8 @@
   LLVMContext Context;
   std::unique_ptr<Module> OriginalProgram =
       parseInputFile(InputFilename, Context);
+  LastIntersting = OriginalProgram.get();
+  sys::AddSignalHandler(onCrashHandler, nullptr);
 
   // Initialize test environment
   TestRunner Tester(TestFilename, TestArguments);
Index: llvm/tools/llvm-reduce/deltas/Delta.cpp
===================================================================
--- llvm/tools/llvm-reduce/deltas/Delta.cpp
+++ llvm/tools/llvm-reduce/deltas/Delta.cpp
@@ -21,6 +21,8 @@
 
 using namespace llvm;
 
+extern Module *volatile LastIntersting;
+
 bool IsReduced(Module &M, TestRunner &Test, SmallString<128> &CurrentFilepath) {
   // Write Module to tmp file
   int FD;
@@ -148,6 +150,7 @@
       FoundAtLeastOneNewUninterestingChunkWithCurrentGranularity = true;
       UninterestingChunks.insert(ChunkToCheckForUninterestingness);
       ReducedProgram = std::move(Clone);
+      LastIntersting = ReducedProgram.get();
       errs() << " **** SUCCESS | lines: " << getLines(CurrentFilepath) << "\n";
     }
     // Delete uninteresting chunks


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