[llvm] LoopVectorize/test: add missing CHECK lines, cleanup intrinsic.ll (PR #70202)

[Nikita Popov via llvm-commits]

================
@@ -506,7 +530,7 @@ for.body:                                         ; preds = %entry, %for.body
   %0 = load double, ptr %arrayidx, align 8
   %arrayidx1 = getelementptr inbounds double, ptr %z, i64 %indvars.iv
   %1 = load double, ptr %arrayidx, align 8
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nikic wrote:

```suggestion
  %1 = load double, ptr %arrayidx1, align 8
```
I think this was the intention. Currently the copysign call gets dropped by InstCombine.

https://github.com/llvm/llvm-project/pull/70202