[clang] [clang][PowerPC] Do not extend _BitInt arguments and returns on PPC64 (PR #231734)

[Manjunath S Matti. via cfe-commits]

mmatti-sw wrote:

@hubert-reinterpretcast I agree with you that the updated ABI document is not published. Having said that, Michael Meissner has agreed upon PowerPC64 ABI for _BitInt, though it is yet to be published. Based on which the support for _BitInt on GCC (PowerPC) was added.
Bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117584
Patch: https://gcc.gnu.org/cgit/gcc/commit/?id=83998f47450c088493c971d46ae3b6dadb7242b3.

https://github.com/llvm/llvm-project/pull/231734