[Attributor] Check for noalias call in AAInstanceInfo

[nikic]

Summary

TBH I don't really understand what this code is doing, but going just by naming, it seems like the relevant property of allocation functions of interest here is their uniqueness (in the sense of disjoint provenance), which is encoded by the noalias return attribute. Or does this rely on some other property of allocators as well?

[nikic]

ping

[jdoerfert]

This looks good. I think I used allocation function elsewhere (because of default values) but that doesn't play a role here.

LG

llvm/lib/Transforms/IPO/AttributorAttributes.cpp

auto UsePred = [&](const Use &U, bool &Follow) {
         return true;
       }
       return false;
     };
 
     auto EquivalentUseCB = [&](const Use &OldU, const Use &NewU) {
       if (auto *SI = dyn_cast<StoreInst>(OldU.getUser())) {
         auto *Ptr = SI->getPointerOperand()->stripPointerCasts();
-        if (isa<AllocaInst>(Ptr) && AA::isDynamicallyUnique(A, *this, *Ptr))
-          return true;
-        auto *TLI = A.getInfoCache().getTargetLibraryInfoForFunction(
-            *SI->getFunction());
-        if (isAllocationFn(Ptr, TLI) && AA::isDynamicallyUnique(A, *this, *Ptr))
+        if ((isa<AllocaInst>(Ptr) || isNoAliasCall(Ptr)) &&
+            AA::isDynamicallyUnique(A, *this, *Ptr))
           return true;
       }
       return false;
     };
 
     if (!A.checkForAllUses(UsePred, *this, V, /* CheckBBLivenessOnly */ true,
                            DepClassTy::OPTIONAL,
                            /* IgnoreDroppableUses */ true, EquivalentUseCB))