[llvm] [DebugInfo][LoopLoadElim] Fix missing debug location updates (PR #91839)

[J. Ryan Stinnett via llvm-commits]

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@@ -448,6 +448,10 @@ class LoadEliminationForLoop {
         new LoadInst(Cand.Load->getType(), InitialPtr, "load_initial",
                      /* isVolatile */ false, Cand.Load->getAlign(),
                      PH->getTerminator()->getIterator());
+    // We don't give any debug location to Initial, because it is inserted
+    // into the loop's preheader. A debug location inside the loop will cause
+    // a misleading stepping when debugging. The test preserving-debugloc-store
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jryans wrote:

Hmm, is this an existing test somewhere? Or maybe it's meant to be attached to this PR...? I don't see it in the file list currently.

https://github.com/llvm/llvm-project/pull/91839