[plt-scheme] Are superfluous expressions optimized away?

Are superfluous expressions, like say '() or (void) when not in tail- or
binding- or pass-value-position or any other value-is-used position,
optimized away (maybe only when compiled to byte-code)?  I'm wondering
if conditional compilation macros like (debug expr ...) which expand to
'() or (void) would incur zero performance penalty?  If not, the
performance cost is probably very negligible?

-- 
: Derick
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