[Statepoint] Replace uses of isX functions with idiomatic isa<X>

Now that all of the statepoint related routines have classes with isa support, let's cleanup.

I'm leaving the (dead) utitilities in tree for a few days so that I can do the same cleanup downstream without breakage.

llvm/lib/CodeGen/CodeGenPrepare.cpp

@@ -576,7 +576,7 @@ bool CodeGenPrepare::runOnFunction(Function &F) {
     SmallVector<Instruction *, 2> Statepoints;
     for (BasicBlock &BB : F)
       for (Instruction &I : BB)
-        if (isStatepoint(I))
+        if (isa<GCStatepointInst>(I))
           Statepoints.push_back(&I);
     for (auto &I : Statepoints)
       EverMadeChange |= simplifyOffsetableRelocate(*I);

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

@@ -1134,7 +1134,7 @@ void SelectionDAGBuilder::visit(const Instruction &I) {
   }
 
   if (!I.isTerminator() && !HasTailCall &&
-      !isStatepoint(&I)) // statepoints handle their exports internally
+      !isa<GCStatepointInst>(I)) // statepoints handle their exports internally
     CopyToExportRegsIfNeeded(&I);
 
   CurInst = nullptr;
@@ -2827,7 +2827,7 @@ void SelectionDAGBuilder::visitInvoke(const InvokeInst &I) {
   // available as a virtual register.
   // We already took care of the exported value for the statepoint instruction
   // during call to the LowerStatepoint.
-  if (!isStatepoint(I)) {
+  if (!isa<GCStatepointInst>(I)) {
     CopyToExportRegsIfNeeded(&I);
   }
 

llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

@@ -1518,8 +1518,8 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
         // to keep track of gc-relocates for a particular gc-statepoint. This is
         // done by SelectionDAGBuilder::LowerAsSTATEPOINT, called before
         // visitGCRelocate.
-        if (isa<CallInst>(Inst) && !isStatepoint(Inst) && !isGCRelocate(Inst) &&
-            !isGCResult(Inst)) {
+        if (isa<CallInst>(Inst) && !isa<GCStatepointInst>(Inst) &&
+            !isa<GCRelocateInst>(Inst) && !isa<GCResultInst>(Inst)) {
           OptimizationRemarkMissed R("sdagisel", "FastISelFailure",
                                      Inst->getDebugLoc(), LLVMBB);
 

llvm/lib/IR/SafepointIRVerifier.cpp

@@ -783,7 +783,7 @@ void GCPtrTracker::transferBlock(const BasicBlock *BB, BasicBlockState &BBS,
 
 void GCPtrTracker::transferInstruction(const Instruction &I, bool &Cleared,
                                        AvailableValueSet &Available) {
-  if (isStatepoint(I)) {
+  if (isa<GCStatepointInst>(I)) {
     Cleared = true;
     Available.clear();
   } else if (containsGCPtrType(I.getType()))

llvm/lib/IR/Verifier.cpp

@@ -4702,14 +4702,14 @@ void Verifier::visitIntrinsicCall(Intrinsic::ID ID, CallBase &Call) {
              LandingPad->getParent());
       Assert(InvokeBB->getTerminator(), "safepoint block should be well formed",
              InvokeBB);
-      Assert(isStatepoint(InvokeBB->getTerminator()),
+      Assert(isa<GCStatepointInst>(InvokeBB->getTerminator()),
              "gc relocate should be linked to a statepoint", InvokeBB);
     } else {
       // In all other cases relocate should be tied to the statepoint directly.
       // This covers relocates on a normal return path of invoke statepoint and
       // relocates of a call statepoint.
       auto Token = Call.getArgOperand(0);
-      Assert(isa<Instruction>(Token) && isStatepoint(cast<Instruction>(Token)),
+      Assert(isa<GCStatepointInst>(Token),
              "gc relocate is incorrectly tied to the statepoint", Call, Token);
     }
 

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

@@ -4387,7 +4387,8 @@ static bool isSafeToEliminateVarargsCast(const CallBase &Call,
   // TODO: This is probably something which should be expanded to all
   // intrinsics since the entire point of intrinsics is that
   // they are understandable by the optimizer.
-  if (isStatepoint(&Call) || isGCRelocate(&Call) || isGCResult(&Call))
+  if (isa<GCStatepointInst>(Call) || isa<GCRelocateInst>(Call) ||
+      isa<GCResultInst>(Call))
     return false;
 
   // The size of ByVal or InAlloca arguments is derived from the type, so we

llvm/lib/Transforms/Scalar/PlaceSafepoints.cpp

@@ -189,7 +189,8 @@ static bool needsStatepoint(CallBase *Call, const TargetLibraryInfo &TLI) {
       return false;
   }
 
-  return !(isStatepoint(Call) || isGCRelocate(Call) || isGCResult(Call));
+  return !(isa<GCStatepointInst>(Call) || isa<GCRelocateInst>(Call) ||
+           isa<GCResultInst>(Call));
 }
 
 /// Returns true if this loop is known to contain a call safepoint which

llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp

@@ -2586,7 +2586,7 @@ bool RewriteStatepointsForGC::runOnFunction(Function &F, DominatorTree &DT,
 
   auto NeedsRewrite = [&TLI](Instruction &I) {
     if (const auto *Call = dyn_cast<CallBase>(&I))
-      return !callsGCLeafFunction(Call, TLI) && !isStatepoint(Call);
+      return !callsGCLeafFunction(Call, TLI) && !isa<GCStatepointInst>(Call);
     return false;
   };
 

llvm/lib/Transforms/Utils/StripGCRelocates.cpp

@@ -48,7 +48,7 @@ bool StripGCRelocates::runOnFunction(Function &F) {
   // i.e. not bound to a single statepoint token.
   for (Instruction &I : instructions(F)) {
     if (auto *GCR = dyn_cast<GCRelocateInst>(&I))
-      if (isStatepoint(GCR->getOperand(0)))
+      if (isa<GCStatepointInst>(GCR->getOperand(0)))
         GCRelocates.push_back(GCR);
   }
   // All gc.relocates are bound to a single statepoint token. The order of