On many microarchitectures, yes. Especially for a memory operand.
That said, depending on the size of the constant, 'bt' may be _smaller_
than testl (8-bit constant vs 32-bit one). Which can make up for it.
I haven't checked recent CPU's, it may not matter much on ones that
support 64-bit. But bt with a memop was traditionally quite a bit more
expensive than 'test'.
I too am too lazy to check. Once it's in the slow-path, it doesn't much
matter. We're talking a few cycles here.
Linus
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