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

[deadalnix]

Summary

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

[majnemer]

LGTM

llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp

static Value *foldSelectCttzCtlz(ICmpInst *ICI, Value *TrueVal, Value *FalseVal,
   if (!match(ValueOnZero, m_SpecificInt(SizeOfInBits)))
     return nullptr;
 
   // Check that 'Count' is a call to intrinsic cttz/ctlz. Also check that the
   // input to the cttz/ctlz is used as LHS for the compare instruction.
   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;
 }
 
 /// Return true if we find and adjust an icmp+select pattern where the compare
 /// is with a constant that can be incremented or decremented to match the
 /// minimum or maximum idiom.