[PATCH] D44543: [AsmPrinter] Emit .weak directive for weak linkage on COFF

[Reid Kleckner via Phabricator via llvm-commits]

rnk added a comment.

In D44543#1922223 <https://reviews.llvm.org/D44543#1922223>, @mstorsjo wrote:

> @rnk - what do you think about the two alternative solutions I commented above?


The second change seems simpler, but maybe we should adjust the linkonce predicate name. As I understand it, both solutions will preserve the behavior of existing linkonce* and weak* linkages if a comdat is present, which it pretty much always is unless the user is using the `__attribute__((weak))` extension.

It seems to me like the hasLinkOnceDirective predicate isn't really helping us here. I dug into the history, and I see that back around 2010, it controlled the emission of `.linkonce discard`. It got moved to section emission in rG76a07580a <https://reviews.llvm.org/rG76a07580ad0603c933889b0e5bacd40016cb0f3d>. Then, later, when we made all the object file sections use the standard, non-suffixed names, we folded that into the `.section` directive and stopped using the `.linkonce` directive entirely. So, it seems like maybe the MCAsmInfo feature that we really want here should read something like "avoidWeakIfComdat" or "shouldWeakComdatSymbolsBeExternal" or "isWeakComdatExternal" or something like that. shouldUpgradeWeakComdatToExternal...


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