// Handle bitfield, assume bytes are 8 bits.
addUInt(MemberDie, dwarf::DW_AT_byte_size, None, FieldSize/8);
addUInt(MemberDie, dwarf::DW_AT_bit_size, None, Size);
-
+ //
// The DWARF 2 DW_AT_bit_offset is counting the bits between
// the high end of the aligned storage unit containing the bit
// field to the high end of the bit field.
// FIXME: DWARF 4 states that DW_AT_data_bit_offset (which
// counts from the beginning, regardless of endianness) should
// be used instead.
+ //
+ //
+ // Struct Align Align Align
+ // v v v v
+ // +-----------+-----*-----+-----*-----+--
+ // | ... |b1|b2|b3|b4|
+ // +-----------+-----*-----+-----*-----+--
+ // | | |<-- Size ->| |
+ // |<---- Offset --->| |<--->|
+ // | | | \_ DW_AT_bit_offset (little endian)
+ // | |<--->|
+ // |<--------->| \_ StartBitOffset = DW_AT_bit_offset (big endian)
+ // \ = DW_AT_data_bit_offset (biendian)
+ // \_ OffsetInBytes
uint64_t Offset = DT->getOffsetInBits();
- uint64_t AlignMask = ~(DT->getAlignInBits() - 1);
- uint64_t HiMark = (Offset + FieldSize) & AlignMask;
- uint64_t FieldOffset = (HiMark - FieldSize);
- Offset -= FieldOffset;
-
- // Maybe we need to work from the other end.
- if (Asm->getDataLayout().isLittleEndian())
- Offset = FieldSize - (Offset + Size);
- addUInt(MemberDie, dwarf::DW_AT_bit_offset, None, Offset);
-
- OffsetInBytes = FieldOffset >> 3;
+ uint64_t Align = DT->getAlignInBits() ? DT->getAlignInBits() : FieldSize;
+ uint64_t AlignMask = ~(Align - 1);
+ // The bits from the start of the storage unit to the start of the field.
+ uint64_t StartBitOffset = Offset - (Offset & AlignMask);
+ // The endian-dependent DWARF 2 offset.
+ uint64_t DwarfBitOffset = Asm->getDataLayout().isLittleEndian()
+ ? OffsetToAlignment(Offset + Size, Align)
+ : StartBitOffset;
+
+ // The byte offset of the field's aligned storage unit inside the struct.
+ OffsetInBytes = (Offset - StartBitOffset) / 8;
+ addUInt(MemberDie, dwarf::DW_AT_bit_offset, None, DwarfBitOffset);
} else
// This is not a bitfield.
- OffsetInBytes = DT->getOffsetInBits() >> 3;
+ OffsetInBytes = DT->getOffsetInBits() / 8;
if (DD->getDwarfVersion() <= 2) {
DIELoc *MemLocationDie = new (DIEValueAllocator) DIELoc;