[PATCH] D61634: [clang/llvm] Allow efficient implementation of libc's memory functions in C/C++

[Hal Finkel via Phabricator via cfe-commits]

hfinkel added a comment.

In D61634#1502043 <https://reviews.llvm.org/D61634#1502043>, @efriedma wrote:

> > I have a related patch that turns -fno-builtin* options into module flags
>
> Do you have any opinion on representing -fno-builtin using a module flag vs. a function attribute in IR?  It seems generally more flexible and easier to reason about a function attribute from my perspective.  But I might be missing something about the semantics of -fno-builtin that would make that representation awkward.  Or I guess it might just be more work to implement, given we have some IPO passes that use TargetLibraryInfo?


I think that a function attribute would be better. We generally use these flags only in the context of certain translation units, and when we use LTO, it would be sad if we had to take the most-conservative settings across the entire application. When we insert new function call to a standard library, we always do it in the context of some function. We'd probably need to block inlining in some cases, but that's better than a global conservative setting.


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https://reviews.llvm.org/D61634