Close https://github.com/llvm/llvm-project/issues/71034
See
https://discourse.llvm.org/t/rfc-c-20-modules-introduce-thin-bmi-and-decls-hash/74755
This patch introduces reduced BMI, which doesn't contain the definitions
of functions and variables if its definitions won't contribute to the
ABI.
Testing is a big part of the patch. We want to make sure the reduced BMI
contains the same behavior with the existing and relatively stable
fatBMI. This is pretty helpful for further reduction.
The user interfaces part it left to following patches to ease the
reviewing.
LValuePathSerializationHelper's type properly
Close https://github.com/llvm/llvm-project/issues/58716.
Tested with libcxx's modules build.
When we read the type of
LValuePathSerializationHelper, we didn't read the correct type. We read
the element type as its name suggests. But the problem here is that it
looks like that both the usage and serialization use its type as the
top level type. So here is the mismatch.
Actually, the type of LValuePathSerializationHelper is never used after
Deserialization without the assertion. So it doesn't matter for the
release users. And this patch shouldn't change the behavior too.
Reviewed By: erichkeane
Differential Revision: https://reviews.llvm.org/D139406
