[clang] [llvm] [SystemZ] Do not extend integer arguments in z/OS XPLINK64 ABI (PR #206833)

[Hubert Tong via cfe-commits]

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hubert-reinterpretcast wrote:

> At an unprototyped call site, clang uses RequiredArgs(0) (see arrangeFreeFunctionType in CGCall.cpp), so all arguments are treated as variadic and will be extended. At a function definition with no prototype, clang uses RequiredArgs::All, so all parameters are treated as named and will not be extended.

My understanding (from the conversion on this PR) is that callers do not have to extend for "named" parameters and, therefore, callees may need to extend on their end. Your first sentence is consistent with my understanding, but I am not reading your second sentence in a way that fits.

https://github.com/llvm/llvm-project/pull/206833