search for: otheritfs

...a fourth field is present, it must be a ConstantInt valued at 0 or 1. If it is 1 then the access tag states that the location being accessed is "constant" (meaningpointsToConstantMemory should return true; see other useful AliasAnalysis methods<https://llvm.org/docs/AliasAnalysis.html#OtherItfs>). The TBAA root of the access type and the base type of an access tag must be the same, and that is the TBAA root of the access tag." (https://llvm.org/docs/LangRef.html#tbaa-metadata) But, from what I see, the CodeGenTBAA pass never sets this field. CodeGenTBAA::getAccessTagInfo() calls...

...ot; loads' discussion for a related question. ) > > Looking at TBAA again, I was reminded that TBAA also contains a third field which indicates that "meaning pointsToConstantMemory should return true; see other useful AliasAnalysis methods <http://llvm.org/docs/AliasAnalysis.html#OtherItfs>". Looking at this a bit, it really seems like this flag has the exact same meaning as !invariant.load. > > pointsToConstantMemory returns a value for a Location. Since it is entirely legal to have two Locations which describe the same physical memory, it seems like you'd be...

I'm looking at how to optimize IR which contains reads from a field which is known to be initialized exactly once. I've got an idea on how to approach this, but wanted to see if others have alternate ideas or similar problems which might spark discussion. It feels like there's a potentially generally useful optimization hint here if we can generalize it sufficiently without