Add test for call.preallocated.arg and restore check

Author: nikic

llvm/lib/IR/Verifier.cpp

@@ -5877,7 +5877,9 @@ void Verifier::visitIntrinsicCall(Intrinsic::ID ID, CallBase &Call) {
             "Uses of llvm.call.preallocated.setup must be calls");
       Intrinsic::ID IID = UseCall->getIntrinsicID();
       if (IID == Intrinsic::call_preallocated_arg) {
-        auto *AllocArgIndex = cast<ConstantInt>(UseCall->getArgOperand(1));
+        auto *AllocArgIndex = dyn_cast<ConstantInt>(UseCall->getArgOperand(1));
+        Check(AllocArgIndex != nullptr,
+              "llvm.call.preallocated.alloc arg index must be a constant");
         auto AllocArgIndexInt = AllocArgIndex->getValue();
         Check(AllocArgIndexInt.sge(0) &&
                   AllocArgIndexInt.slt(NumArgs->getValue()),

llvm/test/Verifier/preallocated-invalid.ll

@@ -72,6 +72,14 @@ define void @preallocated_setup_constant() {
     ret void
 }
 
+; CHECK: llvm.call.preallocated.alloc arg index must be a constant
+define void @preallocated_arg_constant() {
+    %ac = call i32 @blackbox()
+    %cs = call token @llvm.call.preallocated.setup(i32 3)
+    call token @llvm.call.preallocated.arg(token %cs, i32 %ac)
+    ret void
+}
+
 ; CHECK: must be between 0 and corresponding
 define void @preallocated_setup_arg_index_in_bounds() {
     %cs = call token @llvm.call.preallocated.setup(i32 2)