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<h4 class="section">AT&amp;T Syntax bugs</h4>



   <p>The UnixWare assembler, and probably other AT&amp;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.



   <p>For example



<pre class="smallexample">             fsub %st,%st(3)

     </pre>



<p>results in <code>%st(3)</code> being updated to <code>%st - %st(3)</code> rather

than the expected <code>%st(3) - %st</code>.  This happens with all the

non-commutative arithmetic floating point operations with two register

operands where the source register is <code>%st</code> and the destination

register is <code>%st(i)</code>.



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