Wrong machine code

[Dong Jianxiong]

Dear GNU community,
    Recently I found a bug from GNU Assembler. It translates the
"fsubr %st, %st(1)" into the incorrect machine code. The bug summary is
given as follows:

-----------------------------------------------------------
Plat:
CPU: Pentium 4, 2.0Ghz
linux2.4.9
gcc: i686-pc-linux-gnu/ version 3.2.3
as: GNU Assembler 2.11.90.0.8. It is configured for a target of
   'i386-redhat-linux'.

-------------------------------------------------------------
The above assembler translates the above instruction to the incorrect
machine code 'DC E9'.

The correct machine code should be 'DC E1'

You can visit Intel website and download the reference guide for P4
instruction set.

http://www.intel.com/design/pentium4/manuals/245471.htm

download the PDF file and use Acrobat to open it.
read the description of "fsubr" on the page 335.
---------------------------------------------------------------

Finally, I attach an assemble source code file "bug.s" which consists of
five instructions.

gcc -c bug.s //generate the object file bug.o

objdump -S bug.o //view the machine code for each instruction

Regard

Jianxiong Dong

-- 
//////////////////////////////////////////////////////////////
 JIANXIONG DONG

 Centre for Pattern Recognition and Machine Intelligence
 GM606, Concordia University
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 Montreal Quebec H3G 1M8, Canada

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//////////////////////////////////////////////////////////////

bug.s
Description: Text document