+ // Emit mask.
+ bool isPiece = SizeInBits > 0;
+ if (isSubRegister || isPiece) {
+ const unsigned SizeOfByte = 8;
+ unsigned RegSizeInBits = RI->getSubRegIdxSize(Idx);
+ unsigned RegOffsetInBits = RI->getSubRegIdxOffset(Idx);
+ unsigned PieceSizeInBits = std::max(SizeInBits, RegSizeInBits);
+ unsigned PieceOffsetInBits = OffsetInBits ? OffsetInBits : RegOffsetInBits;
+ assert(RegSizeInBits >= SizeInBits && "register smaller than value");
+
+ if (RegOffsetInBits != PieceOffsetInBits) {
+ // Manually shift the value into place, since the DW_OP_piece
+ // describes the part of the variable, not the position of the
+ // subregister.
+ addUInt(TheDie, dwarf::DW_FORM_data1, dwarf::DW_OP_constu);
+ addUInt(TheDie, dwarf::DW_FORM_data1, RegOffsetInBits);
+ addUInt(TheDie, dwarf::DW_FORM_data1, dwarf::DW_OP_shr);
+ }
+
+ if (PieceOffsetInBits > 0 || PieceSizeInBits % SizeOfByte) {
+ assert(PieceSizeInBits > 0 && "piece has zero size");