[llvm] r254819 - [opt] Fix run-twice option for non-idempotent passes

[Keno Fischer via llvm-commits]

Author: kfischer
Date: Fri Dec  4 19:38:12 2015
New Revision: 254819

URL: http://llvm.org/viewvc/llvm-project?rev=254819&view=rev
Log:
[opt] Fix run-twice option for non-idempotent passes

Cloning the module was supposed to guard against the possibility
that the passes may be non-idempotent. However, for some reason
I decided to put that AFTER the passes had already run on the
module, defeating the point entirely. Fix that by moving up the
CloneModule as is done in llc.

Modified:
    llvm/trunk/tools/opt/opt.cpp

Modified: llvm/trunk/tools/opt/opt.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/opt/opt.cpp?rev=254819&r1=254818&r2=254819&view=diff
==============================================================================
--- llvm/trunk/tools/opt/opt.cpp (original)
+++ llvm/trunk/tools/opt/opt.cpp Fri Dec  4 19:38:12 2015
@@ -614,22 +614,26 @@ int main(int argc, char **argv) {
   // Before executing passes, print the final values of the LLVM options.
   cl::PrintOptionValues();
 
+  // If requested, run all passes again with the same pass manager to catch
+  // bugs caused by persistent state in the passes
+  if (RunTwice) {
+      std::unique_ptr<Module> M2(CloneModule(M.get()));
+      Passes.run(*M2);
+      CompileTwiceBuffer = Buffer;
+      Buffer.clear();
+  }
+
   // Now that we have all of the passes ready, run them.
   Passes.run(*M);
 
-  // If requested, run all passes again with the same pass manager to catch
-  // bugs caused by persistent state in the passes
+  // Compare the two outputs and make sure they're the same
   if (RunTwice) {
     assert(Out);
-    CompileTwiceBuffer = Buffer;
-    Buffer.clear();
-    std::unique_ptr<Module> M2(CloneModule(M.get()));
-    Passes.run(*M2);
     if (Buffer.size() != CompileTwiceBuffer.size() ||
         (memcmp(Buffer.data(), CompileTwiceBuffer.data(), Buffer.size()) !=
          0)) {
       errs() << "Running the pass manager twice changed the output.\n"
-                "Writing the result of the second run to the specified output."
+                "Writing the result of the second run to the specified output.\n"
                 "To generate the one-run comparison binary, just run without\n"
                 "the compile-twice option\n";
       Out->os() << BOS->str();