[mlir] Fixed dynamic operand storage on big-endian machines.

Many tests fails by D101969 (https://reviews.llvm.org/D101969)
on big-endian machines. This patch changes bit order of
TrailingOperandStorage in big-endian machines. This patch
works on System Z (Triple = "s390x-ibm-linux", CPU = "z14").

Signed-off-by: Haruki Imai <imaihal@jp.ibm.com>

Reviewed By: rriddle

Differential Revision: https://reviews.llvm.org/D104225

Author: imaihal

mlir/include/mlir/IR/OperationSupport.h

@@ -484,7 +484,11 @@ namespace detail {
 /// This class contains the information for a trailing operand storage.
 struct TrailingOperandStorage final
     : public llvm::TrailingObjects<TrailingOperandStorage, OpOperand> {
+#if defined(BYTE_ORDER) && defined(BIG_ENDIAN) && (BYTE_ORDER == BIG_ENDIAN)
+  TrailingOperandStorage() : numOperands(0), capacity(0), reserved(0) {}
+#else
   TrailingOperandStorage() : reserved(0), capacity(0), numOperands(0) {}
+#endif
   ~TrailingOperandStorage() {
     for (auto &operand : getOperands())
       operand.~OpOperand();
@@ -495,12 +499,21 @@ struct TrailingOperandStorage final
     return {getTrailingObjects<OpOperand>(), numOperands};
   }
 
+#if defined(BYTE_ORDER) && defined(BIG_ENDIAN) && (BYTE_ORDER == BIG_ENDIAN)
+  /// The number of operands within the storage.
+  unsigned numOperands;
+  /// The total capacity number of operands that the storage can hold.
+  unsigned capacity : 31;
+  /// We reserve a range of bits for use by the operand storage.
+  unsigned reserved : 1;
+#else
   /// We reserve a range of bits for use by the operand storage.
   unsigned reserved : 1;
   /// The total capacity number of operands that the storage can hold.
   unsigned capacity : 31;
   /// The number of operands within the storage.
   unsigned numOperands;
+#endif
 };
 
 /// This class handles the management of operation operands. Operands are