[llvm] [CHERI] Refine LoopIdiomRecognize handling of non-integral pointers. (PR #189402)

[Nikita Popov via llvm-commits]

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@@ -472,9 +472,10 @@ LoopIdiomRecognize::isLegalStore(StoreInst *SI) {
   Value *StorePtr = SI->getPointerOperand();
 
   // Don't convert stores of non-integral pointer types to memsets (which stores
-  // integers).
-  if (DL->isNonIntegralPointerType(StoredVal->getType()->getScalarType()))
-    return LegalStoreKind::None;
+  // integers), except for null pointers which are an exception.
+  bool NonIntegralPtrStore =
+      DL->isNonIntegralPointerType(StoredVal->getType()->getScalarType()) &&
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nikic wrote:

We should also replace the isNonIntegralPointerType() check with one for external state. Pointers with (non-external) metadata bits should be completely fine for these transforms.

https://github.com/llvm/llvm-project/pull/189402