**Summary**
When filling out the LayoutInfo for a structure with the offsets
from DWARF, LLDB fills gaps in the layout by creating unnamed
bitfields and adding them to the AST. If we don't do this correctly
and our layout has overlapping fields, we will hat an assertion
in `clang::CGRecordLowering::lower()`. Specifically, if we have
a derived class with a VTable and a bitfield immediately following
the vtable pointer, we create a layout with overlapping fields.
This is an oversight in some of the previous cleanups done around this
area.
In `D76808`, we prevented LLDB from creating unnamed bitfields if there
was a gap between the last field of a base class and the start of a bitfield
in the derived class.
In `D112697`, we started accounting for the vtable pointer. The intention
there was to make sure the offset bookkeeping accounted for the
existence of a vtable pointer (but we didn't actually want to create
any AST nodes for it). Now that `last_field_info.bit_size` was being
set even for artifical fields, the previous fix `D76808` broke
specifically for cases where the bitfield was the first member of a
derived class with a vtable (this scenario wasn't tested so we didn't
notice it). I.e., we started creating redundant unnamed bitfields for
where the vtable pointer usually sits. This confused the lowering logic
in clang.
This patch adds a condition to `ShouldCreateUnnamedBitfield` which
checks whether the first field in the derived class is a vtable ptr.
**Testing**
* Added API test case
Differential Revision: https://reviews.llvm.org/D150591
`DWARFASTParserClang::ParseSingleMember` turns DWARF DIEs that describe
struct/class members into their respective Clang representation (e.g.,
clang::FieldDecl). It also updates a record of where the last field
started/ended so that we can speculatively fill any holes between a field and a
bitfield with unnamed bitfield padding.
Right now we are completely ignoring 'artificial' members when parsing the DWARF
of a struct/class. The only artificial member that seems to be emitted in
practice for C/C++ seems to be the vtable pointer.
By completely skipping both the Clang AST node creation and the updating of the
last-field record, we essentially leave a hole in our layout with the size of
our artificial member. If the next member is a bitfield we then speculatively
fill the hole with an unnamed bitfield. During CodeGen Clang inserts an
artificial vtable pointer into the layout again which now occupies the same
offset as the unnamed bitfield. This later brings down Clang's
`CGRecordLowering::insertPadding` when it checks that none of the fields of the
generated record layout overlap.
Note that this is not a Clang bug. We explicitly set the offset of our fields in
LLDB and overwrite whatever Clang makes up.
Reviewed By: labath
Differential Revision: https://reviews.llvm.org/D112697
* clang-format test source.
* Removed the dead setup code.
* Using expect_expr etc. instead of raw expect.
* Slightly expanded with tests for vtable pointers (which mostly just crash atm.)
* Removed some other minor test guideline problems.
`bool` is considered to be unsigned according to `std::is_unsigned<bool>::value` (and `Type::GetTypeInfo`). Encoding it as signed int works fine for normal variables and fields, but breaks when reading the values of boolean bitfields. If the field is declared as `bool b : 1` and has a value of `0b1`, the call to `SBValue::GetValueAsSigned()` will return `-1`.
Reviewed By: teemperor
Differential Revision: https://reviews.llvm.org/D102685
When parsing DWARF and laying out bit-fields we don't properly take into account when they are in a union, they will all have a zero offset.
Differential Revision: https://reviews.llvm.org/D91118
When parsing DWARF and laying out bit-fields we currently don't take into account whether we have a base class or not.
Currently if the first field is a bit-field but the bit offset is due a field we inherit from a base class we currently
treat it as an unnamed bit-field and therefore add an extra field.
This fix will not check if we have a base class and assume that this offset is due to members we are inheriting from the base.
We are currently seeing asserts during codegen when debugging clang::DiagnosticOptions.
This assumption will fail in the case where the first field in the derived class in an unnamed bit-field. Fixing the first field
being an unnamed bit-field looks like it will require a larger change since we will need a way to track or discover the last field offset of the bases(s).
Differential Revision: https://reviews.llvm.org/D76808
Summary: Moves lldbsuite tests to lldb/test/API.
This is a largely mechanical change, moved with the following steps:
```
rm lldb/test/API/testcases
mkdir -p lldb/test/API/{test_runner/test,tools/lldb-{server,vscode}}
mv lldb/packages/Python/lldbsuite/test/test_runner/test lldb/test/API/test_runner
for d in $(find lldb/packages/Python/lldbsuite/test/* -maxdepth 0 -type d | egrep -v "make|plugins|test_runner|tools"); do mv $d lldb/test/API; done
for d in $(find lldb/packages/Python/lldbsuite/test/tools/lldb-vscode -maxdepth 1 -mindepth 1 | grep -v ".py"); do mv $d lldb/test/API/tools/lldb-vscode; done
for d in $(find lldb/packages/Python/lldbsuite/test/tools/lldb-server -maxdepth 1 -mindepth 1 | egrep -v "gdbremote_testcase.py|lldbgdbserverutils.py|socket_packet_pump.py"); do mv $d lldb/test/API/tools/lldb-server; done
```
lldb/packages/Python/lldbsuite/__init__.py and lldb/test/API/lit.cfg.py were also updated with the new directory structure.
Reviewers: labath, JDevlieghere
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D71151
