Re: [Qemu-devel] [V3 PATCH 02/14] target-ppc: Add ISA2.06 bpermd Instruction

[Richard Henderson <rth@twiddle.net>]

On 12/27/2013 04:23 PM, Scott Wood wrote:
> On Tue, 2013-12-24 at 07:17 -0800, Richard Henderson wrote:
>> On 12/18/2013 12:48 PM, Tom Musta wrote:
>>> +DEF_HELPER_3(bpermd, i64, env, i64, i64)
>>
>> Should be DEF_HELPER_FLAGS_2(bpermd, TCG_CALL_NO_RWG_SE, i64, i64, i64)
>>
>>> +uint64_t helper_bpermd(CPUPPCState *env, uint64_t rs, uint64_t rb)
>>> +{
>>> +    int i;
>>> +    uint64_t ra = 0;
>>> +
>>> +    for (i = 0; i < 8; i++) {
>>> +        int index = (rs >> (i*8)) & 0xFF;
>>> +        if (index < 64) {
>>> +            if (rb & (1ul << (63-index))) {
>>> +                ra |= 1 << i;
>>> +            }
>>> +        }
>>> +    }
>>> +    return ra;
>>> +}
>>> +
>>
>> You don't need env as an argument; it's unused.
>>
>> Why is all of this specific to ppc64?  Can't you run an ISA2.06B machine in
>> 32-bit mode?
> 
> bpermd is a 64-bit instruction.  32-bit implementations do not have it.

What has that got to do with running a 64-bit chip in 32-bit mode?


r~