[lldb][DWARFASTParserClang] Prevent unnamed bitfield creation in the presence of overlapping fields #10591
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adrian-prantl
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… into helper (llvm#108196) This logic will need adjusting soon for llvm#108155 This patch pulls out the logic for detecting/creating unnamed bitfields out of `ParseSingleMember` to make the latter (in my opinion) more readable. Otherwise we have a large number of similarly named variables in scope. (cherry picked from commit f0c6d30)
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Michael137
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…presence of overlapping fields (llvm#108343) This bug surfaced after llvm#105865 (currently reverted, but blocked on this to be relanded). Because Clang doesn't emit `DW_TAG_member`s for unnamed bitfields, LLDB has to make an educated guess about whether they existed in the source. It does so by checking whether there is a gap between where the last field ended and the currently parsed field starts. In the example test case, the empty field `padding` was folded into the storage of `data`. Because the `bit_offset` of `padding` is `0x0` and its `DW_AT_byte_size` is `0x1`, LLDB thinks the field ends at `0x1` (not quite because we first round the size to a word size, but this is an implementation detail), erroneously deducing that there's a gap between `flag` and `padding`. This patch adds the notion of "effective field end", which accounts for fields that share storage. It is set to the end of the storage that the two fields occupy. Then we use this to check for gaps in the unnamed bitfield creation logic. (cherry picked from commit a6a547f)
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Because Clang doesn't emit
DW_TAG_members for unnamed bitfields, LLDBhas to make an educated guess about whether they existed in the source.
It does so by checking whether there is a gap between where the last
field ended and the currently parsed field starts. In the example test
case, the empty field
paddingwas folded into the storage ofdata.Because the
bit_offsetofpaddingis0x0and itsDW_AT_byte_sizeis
0x1, LLDB thinks the field ends at0x1(not quite because wefirst round the size to a word size, but this is an implementation
detail), erroneously deducing that there's a gap between
flagandpadding.This patch adds the notion of "effective field end", which accounts for
fields that share storage. It is set to the end of the storage that the
two fields occupy. Then we use this to check for gaps in the unnamed
bitfield creation logic.
(cherry picked from commit a6a547f)