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Re: gcc-4.3.0/ppc32 inline assembly produces bad code

Daniel Jacobowitz <> writes:

> On Wed, Mar 26, 2008 at 09:25:05AM -0700, Till Straumann wrote:
>> Is my inline assembly wrong or is this a gcc bug ?
> Your inline assembly seems wrong.

I don't think so.

>> /* Powerpc I/O barrier instruction */
>> #define EIEIO(pmem) do { asm volatile("eieio":"=m"(*pmem):"m"(*pmem)); }  
>> while (0)
> An output memory doesn't mean what you think.

IMHO the usage here is perfectly correct.

> I suspect GCC gave you an input memory operand as "%r0(%r9)" and an
> output memory operand as "%r9", and expected the asm to do what it
> said it would do with its operands.

The actual operands are 16(%r3) and 16(%r9).  But the asm statement
correctly declares to only write to memory, and is not supposed to
change %r9 in any way.


Andreas Schwab, SuSE Labs,
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
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