llvm / llvm/llvm-project

[X86] Missed optimization for SIMD `icmp uge 16xi8` when one of the paramters is known to be less than `0x80`

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backend:X86 missed-optimization
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Description

https://godbolt.org/z/KTTPcKP58

Rust issue: https://github.com/rust-lang/stdarch/issues/2154#issuecomment-4644311978

When every byte in the rhs is `<= 0x80`, this can be simpified to `bitmask(saturating_add(lhs, 0x80 - rhs))`

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