[PATCH] D57450: [RISCV] Set MaxAtomicInlineWidth and MaxAtomicPromoteWidth for RV32/RV64 targets with atomics

[Sam Elliott via Phabricator via cfe-commits]

lenary added a comment.

@jyknight I hear where you're coming from. I'll see what I can do about the psABI document.

In that ticket, it's mentioned that the Darwin ABI explicitly says that non-power-of-two atomic types should be padded and realigned, but I cannot find any documentation explaining this. That would be useful, given presumably GCC does have to pad/align on Darwin.

Then the only outstanding question relates to zero-sized atomics, which GCC does not pad, but I think Clang has to pad to get the semantics correct, based on this comment: https://github.com/llvm/llvm-project/blob/master/clang/lib/AST/ASTContext.cpp#L2176


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  https://reviews.llvm.org/D57450/new/

https://reviews.llvm.org/D57450