[PATCH] D94180: [SimplifyCFG] Optimize CFG when null is passed to a function with nonnull argument.

[Johannes Doerfert via Phabricator via llvm-commits]

jdoerfert added a comment.

(Don't wait for me to finish the review)



================
Comment at: llvm/lib/Transforms/Utils/SimplifyCFG.cpp:6591-6592
+    if (auto *CB = dyn_cast<CallBase>(Use)) {
+      if (NullPointerIsDefined(CB->getFunction()))
+        return false;
+      // A call to null is undefined.
----------------
xbolva00 wrote:
> lebedev.ri wrote:
> > And what if `C` is actually `undef`?
> So in this case, we require noundef attribute only (?) @aqjune
> 
> I will add a testcase.
`noundef undef` -> instant UB


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