[Mesa-dev] [PATCH 01/13] nir: allow 64 bit shifts

[Karol Herbst]

On Wed, Feb 28, 2018 at 9:46 PM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> I do not think this patch does what you think it does.  The old opcode
> allowed you to shift any bit size integer by a 32-bit integer.  The new
> version allows you to shift N bits by N bits.  In particular, you can't
> shift a 16-bit by a 32-bit value.
>
> I'm not sure what the best thing is to do here.  Really, the size of src1
> doesn't really matter as 8-bit is enough to do any shifting needed for a
> 64-bit src0.  You can always compose with a u2u32 to get any src1 bit size
> you want.  We picked 32 because it's been the GL default for a long time.
>

Well the thing is we ended up with a shift in spirv having two 64 bit
parameters. Maybe we could just put a convert in it for such cases?

> On Wed, Feb 28, 2018 at 11:51 AM, Rob Clark <robdclark at gmail.com> wrote:
>>
>> From: Karol Herbst <kherbst at redhat.com>
>>
>> This is a thing for OpenCL kernels.
>>
>> Signed-off-by: Rob Clark <robdclark at gmail.com>
>> ---
>>  src/compiler/nir/nir_opcodes.py | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/src/compiler/nir/nir_opcodes.py
>> b/src/compiler/nir/nir_opcodes.py
>> index 278562b2bd1..c4d2c7805eb 100644
>> --- a/src/compiler/nir/nir_opcodes.py
>> +++ b/src/compiler/nir/nir_opcodes.py
>> @@ -479,9 +479,9 @@ binop("seq", tfloat32, commutative, "(src0 == src1) ?
>> 1.0f : 0.0f") # Set on Equ
>>  binop("sne", tfloat32, commutative, "(src0 != src1) ? 1.0f : 0.0f") # Set
>> on Not Equal
>>
>>
>> -opcode("ishl", 0, tint, [0, 0], [tint, tuint32], "", "src0 << src1")
>> -opcode("ishr", 0, tint, [0, 0], [tint, tuint32], "", "src0 >> src1")
>> -opcode("ushr", 0, tuint, [0, 0], [tuint, tuint32], "", "src0 >> src1")
>> +opcode("ishl", 0, tint, [0, 0], [tint, tuint], "", "src0 << src1")
>> +opcode("ishr", 0, tint, [0, 0], [tint, tuint], "", "src0 >> src1")
>> +opcode("ushr", 0, tuint, [0, 0], [tuint, tuint], "", "src0 >> src1")
>>
>>  # bitwise logic operators
>>  #
>> --
>> 2.14.3
>>
>