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.
Close https://github.com/llvm/llvm-project/issues/56916
Within C++20 modules, we may have multiple same constructors in
multiple same RecordDecls. And it doesn't make sense naturally to create
duplicated deduction guides for the duplicated constructors.
Close https://github.com/llvm/llvm-project/issues/61317
The root cause of the problem is that we profile TemplateName by the
non-canonical decls so that the compiler thought they are two different
types. But this is not true. We fixed the issue after we profile the
template name by using the same name.
