[OpenACC] verify acc::DeclareEnterOp operand not BlockArgument (#158095)

Check that the operand of acc::DeclareEnterOp is a BlockArgument before
trying to get its defining operation so it will not segfault and instead
produce a clean error. Add test case.

Author: rscottmanley

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

@@ -3513,7 +3513,8 @@ checkDeclareOperands(Op &op, const mlir::ValueRange &operands,
         "at least one operand must appear on the declare operation");
 
   for (mlir::Value operand : operands) {
-    if (!mlir::isa<acc::CopyinOp, acc::CopyoutOp, acc::CreateOp,
+    if (isa<BlockArgument>(operand) ||
+        !mlir::isa<acc::CopyinOp, acc::CopyoutOp, acc::CreateOp,
                    acc::DevicePtrOp, acc::GetDevicePtrOp, acc::PresentOp,
                    acc::DeclareDeviceResidentOp, acc::DeclareLinkOp>(
             operand.getDefiningOp()))

mlir/test/Dialect/OpenACC/invalid.mlir

@@ -831,3 +831,12 @@ func.func @acc_loop_container() {
 %value = memref.alloc() : memref<f32>
 // expected-error @below {{invalid data clause modifiers: readonly}}
 %0 = acc.create varPtr(%value : memref<f32>) -> memref<f32> {modifiers = #acc<data_clause_modifier readonly,zero,capture,always>}
+
+// -----
+
+func.func @verify_declare_enter(%arg0 : memref<i32>) {
+// expected-error @below {{expect valid declare data entry operation or acc.getdeviceptr as defining op}}
+  %0 = acc.declare_enter dataOperands(%arg0 : memref<i32>)
+  acc.declare_exit token(%0) dataOperands(%arg0 : memref<i32>)
+  return
+}