Re: [Qemu-devel] tcg shift ops and magnitudes larger than register size

[Edgar E. Iglesias]

On Wed, Jan 12, 2011 at 08:13:45PM -0500, Mike Frysinger wrote:
> are there any rules with the tcg sar/shl/shr ops and their magnitudes
> ?  such as "magnitudes cannot be larger than the register size" ?

Yes, the result is undefined in those cases.
 
> i have a 32bit register with the value of 0x1230002 and when i attempt
> to do a sari with a value >=32, it gives me 0x918001 (a single shift
> right has been done).  i would have expected the value to be 0 (as
> that is what my architecture does).

You need to handle it in the translator. CRIS has similar semantics
as your arch. See target-cris/translate.c:t_gen_lsl() for one way
of doing it. There might be better ways though.

Cheers