[IR] Use immarg for preallocated intrinsics (NFC)

Mark the attributes as immarg to indicate that they require a
constant integer. This was previously enforced with a manual
verifier check.

Author: nikic

llvm/include/llvm/IR/Intrinsics.td

@@ -977,8 +977,12 @@ def int_instrprof_mcdc_tvbitmap_update : Intrinsic<[],
                                         [llvm_ptr_ty, llvm_i64_ty,
                                          llvm_i32_ty, llvm_ptr_ty]>;
 
-def int_call_preallocated_setup : DefaultAttrsIntrinsic<[llvm_token_ty], [llvm_i32_ty]>;
-def int_call_preallocated_arg : DefaultAttrsIntrinsic<[llvm_ptr_ty], [llvm_token_ty, llvm_i32_ty]>;
+def int_call_preallocated_setup
+    : DefaultAttrsIntrinsic<[llvm_token_ty], [llvm_i32_ty],
+                            [ImmArg<ArgIndex<0>>]>;
+def int_call_preallocated_arg
+    : DefaultAttrsIntrinsic<[llvm_ptr_ty], [llvm_token_ty, llvm_i32_ty],
+                            [ImmArg<ArgIndex<1>>]>;
 def int_call_preallocated_teardown : DefaultAttrsIntrinsic<[], [llvm_token_ty]>;
 
 // This intrinsic is intentionally undocumented and users shouldn't call it;

llvm/lib/IR/Verifier.cpp

@@ -5869,19 +5869,15 @@ void Verifier::visitIntrinsicCall(Intrinsic::ID ID, CallBase &Call) {
     break;
   }
   case Intrinsic::call_preallocated_setup: {
-    auto *NumArgs = dyn_cast<ConstantInt>(Call.getArgOperand(0));
-    Check(NumArgs != nullptr,
-          "llvm.call.preallocated.setup argument must be a constant");
+    auto *NumArgs = cast<ConstantInt>(Call.getArgOperand(0));
     bool FoundCall = false;
     for (User *U : Call.users()) {
       auto *UseCall = dyn_cast<CallBase>(U);
       Check(UseCall != nullptr,
             "Uses of llvm.call.preallocated.setup must be calls");
       Intrinsic::ID IID = UseCall->getIntrinsicID();
       if (IID == Intrinsic::call_preallocated_arg) {
-        auto *AllocArgIndex = dyn_cast<ConstantInt>(UseCall->getArgOperand(1));
-        Check(AllocArgIndex != nullptr,
-              "llvm.call.preallocated.alloc arg index must be a constant");
+        auto *AllocArgIndex = cast<ConstantInt>(UseCall->getArgOperand(1));
         auto AllocArgIndexInt = AllocArgIndex->getValue();
         Check(AllocArgIndexInt.sge(0) &&
                   AllocArgIndexInt.slt(NumArgs->getValue()),

llvm/test/Verifier/preallocated-invalid.ll

@@ -65,7 +65,7 @@ define void @preallocated_one_call() {
     ret void
 }
 
-; CHECK: must be a constant
+; CHECK: immarg operand has non-immediate parameter
 define void @preallocated_setup_constant() {
     %ac = call i32 @blackbox()
     %cs = call token @llvm.call.preallocated.setup(i32 %ac)