tree e97f300b2f3906fb57b525730df01621a85d7274
parent 0c58ab21aace31e08f9c96a95b538e69e705ba3e
author Philip Reames <listmail@philipreames.com> 1618612095 -0700
committer Copybara-Service <copybara-worker@google.com> 1618720210 -0700

[inferattrs] Don't infer lib func attributes for nobuiltin functions

If we have a nobuiltin function, we can't assume we know anything about the implementation.

I noticed this when tracing through a log from an in the wild miscompile (https://github.com/emscripten-core/emscripten/issues/9443) triggered after 8666463.  We were incorrectly assuming that a custom allocator could not free.  (It's not clear yet this is the only problem in said issue.)

I also noticed something similiar mentioned in the commit message of ab243e when scrolling back through history.  Through, from what I can tell, that commit fixed symptom not root cause.

The interface we have for library function detection is extremely error prone, but given the interaction between ``nobuiltin`` decls and ``builtin`` callsites, it's really hard to imagine something much cleaner.  I may iterate on that, but it'll be invasive enough I didn't want to hold an obvious functional fix on it.

GitOrigin-RevId: 11707435ccb44a9377bfed407453e0646a159636