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Hello, While looking at some internal benchmarks, I found that llvm generates codes with redundant promotion, something like: xor %al, %cl movzbl %cl, %ecx cmp $0x20, %ecx I believe that the promotion stems from the logic in X86TargetLowering::EmitCmp. Comments in the code says, "Do the comparison at i32 if it's smaller, besides the Atom case. This avoids subregister aliasing issues.

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