[llvm] [LICM][SimplifyCFG] Ignore frees for writable dereferenceability check (PR #202589)

[Antonio Frighetto via llvm-commits]

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@@ -2149,9 +2149,13 @@ bool llvm::promoteLoopAccessesToScalars(
   if (StoreSafety == StoreSafetyUnknown) {
     Value *Object = getUnderlyingObject(SomePtr);
     bool ExplicitlyDereferenceableOnly;
+    // The dereferenceability query here is only required to satisfy the
+    // writable contract, actual dereferenceability has already been proven
+    // above. As such, we can ignore frees.
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antoniofrighetto wrote:

Might be missing something here, though where exactly is dereferenceability proven above? I think I'm slightly confused by the preceding comment "We know we can hoist the load, but don't have a guaranteed store.".

https://github.com/llvm/llvm-project/pull/202589