Use InstCombine's builder in foldSelectCttzCtlz instead of creating a new one.

Summary: As per title. This will add the instructiions we are interested in in the worklist.

Reviewers: mehdi_amini, majnemer, andreadb

Differential Revision: https://reviews.llvm.org/D29081

llvm-svn: 292957
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index a889a67..b5718c3 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -395,13 +395,12 @@
   if (match(Count, m_Intrinsic<Intrinsic::cttz>(m_Specific(CmpLHS))) ||
       match(Count, m_Intrinsic<Intrinsic::ctlz>(m_Specific(CmpLHS)))) {
     IntrinsicInst *II = cast<IntrinsicInst>(Count);
-    IRBuilder<> Builder(II);
     // Explicitly clear the 'undef_on_zero' flag.
     IntrinsicInst *NewI = cast<IntrinsicInst>(II->clone());
     Type *Ty = NewI->getArgOperand(1)->getType();
     NewI->setArgOperand(1, Constant::getNullValue(Ty));
-    Builder.Insert(NewI);
-    return Builder.CreateZExtOrTrunc(NewI, ValueOnZero->getType());
+    Builder->Insert(NewI);
+    return Builder->CreateZExtOrTrunc(NewI, ValueOnZero->getType());
   }
 
   return nullptr;