[llvm] [LV] Avoid bailing on SCEVUnknown in uniformity-rew (PR #160144)

[Ramkumar Ramachandra via llvm-commits]

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@@ -528,14 +528,6 @@ class SCEVAddRecForUniformityRewriter
     return SCEVRewriteVisitor<SCEVAddRecForUniformityRewriter>::visit(S);
   }
 
-  const SCEV *visitUnknown(const SCEVUnknown *S) {
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artagnon wrote:

Hm, I'm not sure how a load can read a different value on each iteration which is an SCEVUnknown: wouldn't it be an SCEVAddRec, with an underlying SCEVUnknown, which is still uniform? Will write a test for this to check, thanks.

https://github.com/llvm/llvm-project/pull/160144