[llvm] [Transforms] LoopIdiomRecognize recognize strlen and wcslen (PR #108985)

[Michael Kruse via llvm-commits]

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@@ -1507,9 +1526,11 @@ static Value *matchCondition(BranchInst *BI, BasicBlock *LoopEntry,
   if (!Cond)
     return nullptr;
 
-  ConstantInt *CmpZero = dyn_cast<ConstantInt>(Cond->getOperand(1));
-  if (!CmpZero || !CmpZero->isZero())
-    return nullptr;
+  if (!isa<ConstantPointerNull>(Cond->getOperand(1))) {
+    ConstantInt *CmpZero = dyn_cast<ConstantInt>(Cond->getOperand(1));
+    if (!CmpZero || !CmpZero->isZero())
+      return nullptr;
+  }
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Meinersbur wrote:

Consider introducting a utility function `if (!isZeroConstant(Cond->getOperand(1)))` such as https://github.com/llvm/llvm-project/blob/7de492f90dd733859f5f0dd582860ccc5899dc22/clang/lib/CodeGen/CGPointerAuth.cpp#L169.

Or: Use ScalarEvolution's `isZero`

https://github.com/llvm/llvm-project/pull/108985