[llvm-reduce] Don't reuse SmallVector across calls to getAllMetadata()

[aeubanks]

Summary

The SmallVector is not cleared in calls to getAllMetadata().

[Meinersbur]

LGTM, thanks.

llvm/tools/llvm-reduce/deltas/ReduceMetadata.cpp

static void extractMetadataFromModule(Oracle &O, Module &Program) {
 
   for (NamedMDNode *NN : NamedNodesToDelete) {
     for (auto I : seq<unsigned>(0, NN->getNumOperands()))
       NN->setOperand(I, NULL);
     NN->eraseFromParent();
   }
 
   // Delete out-of-chunk metadata attached to globals.
-  SmallVector<std::pair<unsigned, MDNode *>> MDs;
   for (GlobalVariable &GV : Program.globals()) {
+    SmallVector<std::pair<unsigned, MDNode *>> MDs;
     GV.getAllMetadata(MDs);
     for (std::pair<unsigned, MDNode *> &MD : MDs)
       if (!O.shouldKeep())
         GV.setMetadata(MD.first, NULL);
   }
 
   for (Function &F : Program) {
+    {
+      SmallVector<std::pair<unsigned, MDNode *>> MDs;
       // Delete out-of-chunk metadata attached to functions.
       F.getAllMetadata(MDs);
       for (std::pair<unsigned, MDNode *> &MD : MDs)
         if (!O.shouldKeep())
           F.setMetadata(MD.first, NULL);
+    }
 
     // Delete out-of-chunk metadata attached to instructions.
     for (Instruction &I : instructions(F)) {
+      SmallVector<std::pair<unsigned, MDNode *>> MDs;
       I.getAllMetadata(MDs);
       for (std::pair<unsigned, MDNode *> &MD : MDs)
         if (!O.shouldKeep())
           I.setMetadata(MD.first, NULL);
     }
   }
 }
 
 void llvm::reduceMetadataDeltaPass(TestRunner &Test) {
   outs() << "*** Reducing Metadata...\n";
   runDeltaPass(Test, extractMetadataFromModule);
   outs() << "----------------------------\n";
 }