Re: [Qemu-ppc] [PATCH 8/9] target-ppc: add vextu[bhw]lx instructions

[Nikunj A Dadhania]

David Gibson <address@hidden> writes:

> [ Unknown signature status ]
> On Tue, Nov 22, 2016 at 05:16:04PM +0530, Nikunj A Dadhania wrote:
>> From: Avinesh Kumar <address@hidden>
>> 
>> vextublx:  Vector Extract Unsigned Byte Left
>> vextuhlx:  Vector Extract Unsigned Halfword Left
>> vextuwlx:  Vector Extract Unsigned Word Left
>> 
>> Signed-off-by: Avinesh Kumar <address@hidden>
>> Signed-off-by: Nikunj A Dadhania <address@hidden>
>> ---
>>  target-ppc/helper.h                 |  3 ++
>>  target-ppc/int_helper.c             | 63 
>> +++++++++++++++++++++++++++++++++++++
>>  target-ppc/translate/vmx-impl.inc.c | 18 +++++++++++
>>  target-ppc/translate/vmx-ops.inc.c  |  4 ++-
>>  4 files changed, 87 insertions(+), 1 deletion(-)
>> 
>> diff --git a/target-ppc/helper.h b/target-ppc/helper.h
>> index 3b26678..d0a8fb2 100644
>> --- a/target-ppc/helper.h
>> +++ b/target-ppc/helper.h
>> @@ -366,6 +366,9 @@ DEF_HELPER_3(vpmsumb, void, avr, avr, avr)
>>  DEF_HELPER_3(vpmsumh, void, avr, avr, avr)
>>  DEF_HELPER_3(vpmsumw, void, avr, avr, avr)
>>  DEF_HELPER_3(vpmsumd, void, avr, avr, avr)
>> +DEF_HELPER_2(vextublx, tl, tl, avr)
>> +DEF_HELPER_2(vextuhlx, tl, tl, avr)
>> +DEF_HELPER_2(vextuwlx, tl, tl, avr)
>>  
>>  DEF_HELPER_2(vsbox, void, avr, avr)
>>  DEF_HELPER_3(vcipher, void, avr, avr, avr)
>> diff --git a/target-ppc/int_helper.c b/target-ppc/int_helper.c
>> index 8886a72..fb9f178 100644
>> --- a/target-ppc/int_helper.c
>> +++ b/target-ppc/int_helper.c
>> @@ -1805,6 +1805,69 @@ void helper_vlogefp(CPUPPCState *env, ppc_avr_t *r, 
>> ppc_avr_t *b)
>>      }
>>  }
>>  
>> +#define EXTRACT128(value, start, length)        \
>> +    ((value >> start) & (~(__uint128_t)0 >> (128 - length)))
>
> Although we do use 128-bit arithmetic in some places in qemu, I don't
> think we assume the presence of a working uint1238_t type.  Better to
> actually write a helper function which does this in terms of 64 bit
> arithmetic, I think.

I think we should have it in #if defined(CONFIG_INT128), as the callers
are already within the define.

>> +
>> +#if defined(HOST_WORDS_BIGENDIAN)
>> +#  if defined(CONFIG_INT128)
>> +#  define VEXTULX_DO(name, elem)                                \
>> +target_ulong glue(helper_, name)(target_ulong a, ppc_avr_t *b)  \
>
> It seems a bit odd to need helpers for what's essentially just copying
> a byte/halfword/whatever out of the vector.

Are you suggesting to do this using tcg_ops ?
In tcg, vector is represented as high/low, so the extraction in boundary
cases will get ugly.

>> +{                                                               \
>> +    target_ulong r = 0;                                         \
>> +    int index = (a & 0xf) * 8;                                  \
>> +    r = EXTRACT128(b->u128, index, elem * 8);                   \
>> +    return r;                                                   \
>> +}

Regards
Nikunj