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AT&T Syntax bugs
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   The UnixWare assembler, and probably other AT&T derived ix86 Unix
assemblers, generate floating point instructions with reversed source
and destination registers in certain cases.  Unfortunately, gcc and
possibly many other programs use this reversed syntax, so we're stuck
with it.

   For example

             fsub %st,%st(3)

results in `%st(3)' being updated to `%st - %st(3)' rather than the
expected `%st(3) - %st'.  This happens with all the non-commutative
arithmetic floating point operations with two register operands where
the source register is `%st' and the destination register is `%st(i)'.