[llvm] [Loads] Check if Ptr can be freed between Assume and CtxI. (PR #161255)

[via llvm-commits]

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@@ -391,6 +391,10 @@ bool llvm::isDereferenceableAndAlignedInLoop(
     return false;
 
   Instruction *HeaderFirstNonPHI = &*L->getHeader()->getFirstNonPHIIt();
+  if (BasicBlock *LoopPred = L->getLoopPredecessor()) {
+    if (isa<BranchInst>(LoopPred->getTerminator()))
+      HeaderFirstNonPHI = LoopPred->getTerminator();
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annamthomas wrote:

Nit: This is no longer `HeaderFirstNonPHI`. Pls rename to `CtxI`

https://github.com/llvm/llvm-project/pull/161255