bug in arch/ppc/kernel/misc.S: __ashrdi3?

[Andreas Schwab]

Benjamin Herrenschmidt <benh at kernel.crashing.org> writes:

> On Fri, 2005-07-15 at 18:01 +0200, Frank van Maarseveen wrote:
>> I don't really grok the code but an operand seems to be missing and the
>> assembler makes something out of it I don't trust:
>> 
>> _GLOBAL(__ashrdi3)
>> 	...
>> 	rlwinm  r8,r7,0,32      # t3 = (count < 32) ? 32 : 0
>
> This is equivalent to r8 = r7 & 32. It will definitely not do what the
> comment says though. If (count < 64), however, it will do something
> like r8 = (r7 < 32) ? 0 : 32. Paul, maybe we should dbl check what's
> going in there ?

r7 is count + 32, and ((count + 32) & 32) is equivalent to the expression
above if count < 64.

Andreas.

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Andreas Schwab, SuSE Labs, schwab at suse.de
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