lib: update for LLVM API change

TerminatorInst has been removed and been made into a regular Instruction.  Use
the `isTerminator` function instead of the dyn_cast.

Author: compnerd

lib/IRGen/IRBuilder.h

@@ -82,7 +82,7 @@ class IRBuilder : public IRBuilderBase {
   bool hasPostTerminatorIP() const {
     return GetInsertBlock() != nullptr &&
            !GetInsertBlock()->empty() &&
-           isa<llvm::TerminatorInst>(GetInsertBlock()->back());
+           GetInsertBlock()->back().isTerminator();
   }
 
   void ClearInsertionPoint() {

lib/LLVMPasses/LLVMARCOpts.cpp

@@ -718,7 +718,7 @@ static bool performStoreOnlyObjectElimination(CallInst &Allocation,
       // it is perfectly fine to delete this instruction if all uses of the
       // instruction are also eliminable.
 
-      if (I->mayHaveSideEffects() || isa<TerminatorInst>(I))
+      if (I->mayHaveSideEffects() || I->isTerminator())
         return false;
       break;
 

lib/LLVMPasses/LLVMMergeFunctions.cpp

@@ -312,7 +312,7 @@ class SwiftMergeFunctions : public ModulePass {
     /// Advances the current instruction to the next instruction.
     void nextInst() {
       assert(CurrentInst);
-      if (isa<TerminatorInst>(CurrentInst)) {
+      if (CurrentInst->isTerminator()) {
         auto BlockIter = std::next(CurrentInst->getParent()->getIterator());
         if (BlockIter == F->end()) {
           CurrentInst = nullptr;