Summary:
Correct identification of packing.
Tests were modified to reflect the new behaviour. One test was removed as it was bogus - the flattener pass runs before the alignmentcalc pass and therefore the layout in the test could never happen (i.e. it has a hierarchy).
Reviewed By: JakeHillion
Differential Revision: D53815661
We previously moved container identification later in CodeGen in order
to preserve information for AlignmentCalc.
However, Flattener needs to know if a class is a container in order to
apply its special handling for this case.
This new approach moves container identification in front of Flattener,
but has Container own a type node, representing its layout. This
underlying type node can be used for calculating a container's
alignment in a later pass.
We previously only marked as packed if there was no tail padding, which
was not a sufficient condition.
The new AlignmentCalcTest.PackedMembers test case is an example which
would previously not have been marked as packed.
These aren't used for anything yet, but should be useful for stable IDs
when printing nodes before and after passes and for faster cycle
detection than the current map of pointers.
- Change member and parent offsets to work in bits, not bytes
- Printer still displays offsets in bytes, with decimals when using
bitfields
- AddPadding: Don't pad bitfields
- CodeGen: Emit code for bitfields
