[PATCH] D156845: [ConstantRange] Calculate precise range for shl by -1

[Allen zhong via Phabricator via llvm-commits]

Allen added a comment.

In D156845#4617745 <https://reviews.llvm.org/D156845#4617745>, @goldstein.w.n wrote:

> Can you rebase this?

I don't find this PR has some changes after rebasing. So I have a dig into it, and attached the negative test **positiveShift32**


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