[PATCH] D118673: [Attributor] Introduce the `AA::isPotentiallyReachable` helper APIs

[Johannes Doerfert via Phabricator via llvm-commits]

jdoerfert added inline comments.


================
Comment at: llvm/lib/Transforms/IPO/Attributor.cpp:482
+                        << *CurFromI << " is not checked backwards, abort\n");
+      return true;
+    }
----------------
kuter wrote:
> jdoerfert wrote:
> > kuter wrote:
> > > We haven't called `FnReachabilityAA.instructionCanReach` yet. This function won't do interprocedural reachability if there is no GoBackwardsCB  ?
> > > 
> > Yes, as the comment states, if there is no backwards CB we give up. Nothing right now will otherwise cause this to not return "may reach" anyway. We eventually hit an external function and the callers are unknown and we give up. Once we have logic to determine an internal function can only be reached from specific places, etc. we can do more, unclear if that will be here though.
> I interpreted the comment as not doing any backwards search if there is no callback not "not doing any interprocedural reachability" but ok. 
`return true` = giving up


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  https://reviews.llvm.org/D118673/new/

https://reviews.llvm.org/D118673