[PATCH] D157836: [RFC][IR] Correct lowering of `f128` intrinsics

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

In D157836#4587473 <https://reviews.llvm.org/D157836#4587473>, @tmgross wrote:

> Wouldn't `-mlong-double-128` remain a frontend-only flag since it doesn't affect the libc calls, instead just tells clang whether to lower to `fp128`/`x86_fp80`/`double`?

-mlong-double-128 is an ABI flag; among other things, it specifies the format of the operand/result to sinl.

> In any case, it seem like `long double` logic is quite mixed into other C-specific logic, probably not worth extracting to LLVM. So it seems a module flag will be needed anyway and can provide this information.

It's probably worth some effort to ensure that unmodified targets work correctly without the module flag (for the sake of people writing their own frontends).


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https://reviews.llvm.org/D157836