id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	difficulty
1619	Specialization ignores fixnum mode, leading to suboptimal code	sjamaan		"As we found with #1604, when running with `-fixnum-arithmetic`, specialization happens before optimization.

Because the scrutinizer doesn't know about fixnum mode, this is still something of an issue, because we'd specialize to code that supports bignums, which is allocating. This is problematic in two ways: one is that the generated code that doesn't get replaced will not be able to deal with bignums (resulting in extremely strange behaviour on overflow or when the code results in ratnums), and it's less than optimal because fixnum ops aren't allocating, so they should be faster still.

Perhaps we could stop the scrutinizer from doing replacements that deal with numerics in fixnum mode?"	defect	new	minor	6.0.0	compiler	5.0.0