Invert floating point comparisons such that no extra parity check is required.
This comment pretty much explains it already:
-- We have to worry about unordered operands (eg. comparisons -- against NaN). If the operands are unordered, the comparison -- sets the parity flag, carry flag and zero flag. -- All comparisons are supposed to return false for unordered -- operands except for !=, which returns true. -- -- Optimisation: we don't have to test the parity flag if we -- know the test has already excluded the unordered case: eg > -- and >= test for a zero carry flag, which can only occur for -- ordered operands. -- -- ToDo: by reversing comparisons we could avoid testing the -- parity flag in more cases.
This would turn a sequence of
jp foo jb bar jmp foo
jge foo jmp bar