This makes the C++ ABI depend entirely on the target: MS ABI for -win32 triples,
Itanium otherwise. It's no longer possible to do weird combinations.
To be able to run a test with a specific ABI without constraining it to a
specific triple, new substitutions are added to lit: %itanium_abi_triple and
%ms_abi_triple can be used to get the current target triple adjusted to the
desired ABI. For example, if the test suite is running with the i686-pc-win32
target, %itanium_abi_triple will expand to i686-pc-mingw32.
Differential Revision: http://llvm-reviews.chandlerc.com/D2545
llvm-svn: 199250
Most importantly, this makes our vtable layout match MSVC's. Previously
we would emit a return adjusting thunk whenever the return types
differed, even if the adjustment would have been trivial.
MSVC does emit some trivial return adjusting thunks, but only if there
was already an overridden method that required a return adjustment.
llvm-svn: 198080
Timur Iskhodzhanov