[mlir][openacc] Switch deviceType to optional single operand

[clementval]

Summary

The standard suggests that the value for the device_type clause on the
set directive is a list but this does not makes sense. Restrict the number
of value to one so it matches the runtime function.

[razvanlupusoru]

Yes - this seems right to me now.

mlir/include/mlir/Dialect/OpenACC/OpenACCOps.td

let description = [{
 
     Example:
 
     ```mlir
     acc.set device_num(%dev1 : i32)
     ```
   }];
 
-  let arguments = (ins Variadic<IntOrIndex>:$deviceTypeOperands,
+  let arguments = (ins Optional<IntOrIndex>:$deviceType,
                        Optional<IntOrIndex>:$defaultAsync,
-                       Optional<IntOrIndex>:$deviceNumOperand,
+                       Optional<IntOrIndex>:$deviceNum,
                        Optional<I1>:$ifCond);
 
   let assemblyFormat = [{
     oilist(
-      `device_type` `(` $deviceTypeOperands `:` type($deviceTypeOperands) `)`
+      `device_type` `(` $deviceType `:` type($deviceType) `)`
     | `default_async` `(` $defaultAsync `:` type($defaultAsync) `)`
-    | `device_num` `(` $deviceNumOperand `:` type($deviceNumOperand) `)`
+    | `device_num` `(` $deviceNum `:` type($deviceNum) `)`
     | `if` `(` $ifCond `)`
     ) attr-dict-with-keyword
   }];
   let hasVerifier = 1;
 }
 
 //===----------------------------------------------------------------------===//
 // 2.14.4. Update Directive

mlir/lib/Dialect/OpenACC/IR/OpenACC.cpp

 // SetOp
 //===----------------------------------------------------------------------===//
 
 LogicalResult acc::SetOp::verify() {
   Operation *currOp = *this;
   while ((currOp = currOp->getParentOp()))
     if (isComputeOperation(currOp))
       return emitOpError("cannot be nested in a compute operation");
-  if (getDeviceTypeOperands().empty() && !getDefaultAsync() &&
-      !getDeviceNumOperand())
+  if (!getDeviceType() && !getDefaultAsync() && !getDeviceNum())
     return emitOpError("at least one default_async, device_num, or device_type "
                        "operand must appear");
   return success();
 }
 
 //===----------------------------------------------------------------------===//
 // UpdateOp
 //===----------------------------------------------------------------------===//

mlir/test/Dialect/OpenACC/ops.mlir

 // -----
 
 %i64Value = arith.constant 1 : i64
 %i32Value = arith.constant 1 : i32
 %i32Value2 = arith.constant 2 : i32
 %idxValue = arith.constant 1 : index
 %ifCond = arith.constant true
 acc.set device_type(%i32Value : i32)
-acc.set device_type(%i32Value, %i32Value2 : i32, i32)
+acc.set device_type(%i32Value : i32)
 acc.set device_num(%i64Value : i64)
 acc.set device_num(%i32Value : i32)
 acc.set device_num(%idxValue : index)
 acc.set device_num(%idxValue : index) if(%ifCond)
-acc.set device_num(%idxValue : index) if(%ifCond)
 acc.set default_async(%i32Value : i32)
 
 // CHECK: [[I64VALUE:%.*]] = arith.constant 1 : i64
 // CHECK: [[I32VALUE:%.*]] = arith.constant 1 : i32
 // CHECK: [[I32VALUE2:%.*]] = arith.constant 2 : i32
 // CHECK: [[IDXVALUE:%.*]] = arith.constant 1 : index
 // CHECK: [[IFCOND:%.*]] = arith.constant true
 // CHECK: acc.set device_type([[I32VALUE]] : i32)
-// CHECK: acc.set device_type([[I32VALUE]], [[I32VALUE2]] : i32, i32)
+// CHECK: acc.set device_type([[I32VALUE]] : i32)
 // CHECK: acc.set device_num([[I64VALUE]] : i64)
 // CHECK: acc.set device_num([[I32VALUE]] : i32)
 // CHECK: acc.set device_num([[IDXVALUE]] : index)
 // CHECK: acc.set device_num([[IDXVALUE]] : index) if([[IFCOND]])
-// CHECK: acc.set device_num([[IDXVALUE]] : index) if([[IFCOND]])
 // CHECK: acc.set default_async([[I32VALUE]] : i32)