[llvm] [instcombine] Drop zext nneg flag when simplify operand (PR #71088)

[Nikita Popov via llvm-commits]

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@@ -783,7 +783,7 @@ define i64 @evaluate_zexted_const_expr(i1 %c) {
 ; but the flag on the zext doesn't.
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nikic wrote:

Drop the FIXME in the line above...

https://github.com/llvm/llvm-project/pull/71088