[Mesa-dev] [PATCH] nir: special hack for TGSI vs indirect inputs

[Rob Clark]

Quite possibly I am..  although wouldn't I still have the same issue
with other state trackers?  So in that case I'd have to detect
indirect access, but without ArrayID's, and still set this flag.

BR,
-R

On Mon, Jan 11, 2016 at 11:47 AM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
> Are you looking for PIPE_SHADER_CAP_TGSI_ANY_INOUT_DECL_RANGE perchance?
>
> On Mon, Jan 11, 2016 at 11:44 AM, Rob Clark <robdclark at gmail.com> wrote:
>> From: Rob Clark <robclark at freedesktop.org>
>>
>> TGSI doesn't know about array input (or output[*]) variables.  If the
>> INPUT file is addressed indirectly, we must treat the entire INPUT
>> "register file" as one contiguous array.  However tgsi_to_nir cannot
>> declare all the inputs as a single array var, as this would loose
>> varying slot and interpolation info.
>>
>> This hack provides the extra information that the compiler backend
>> needs so that all the N inputs can be organized as a single array for
>> direct and indirect access.
>>
>> [*] tgsi_to_nir does not generate indirect output stores, otherwise we
>> would need a similar hack for outputs
>>
>> Signed-off-by: Rob Clark <robclark at freedesktop.org>
>> ---
>> Yes, sorry, I know, TGSI is horrible.  But I don't really have any
>> better ideas about how to handle this.
>>
>>  src/gallium/auxiliary/nir/tgsi_to_nir.c |  3 +++
>>  src/glsl/nir/nir.h                      | 14 ++++++++++++++
>>  2 files changed, 17 insertions(+)
>>
>> diff --git a/src/gallium/auxiliary/nir/tgsi_to_nir.c b/src/gallium/auxiliary/nir/tgsi_to_nir.c
>> index 94d992b..4a57f9e 100644
>> --- a/src/gallium/auxiliary/nir/tgsi_to_nir.c
>> +++ b/src/gallium/auxiliary/nir/tgsi_to_nir.c
>> @@ -1973,6 +1973,9 @@ tgsi_to_nir(const void *tgsi_tokens,
>>                                    options);
>>     s = c->build.shader;
>>
>> +   if (c->scan->indirect_files & (1 << TGSI_FILE_INPUT))
>> +      s->info.tgsi_hack_indirect_inputs = true;
>> +
>>     s->num_inputs = scan.file_max[TGSI_FILE_INPUT] + 1;
>>     s->num_uniforms = scan.const_file_max[0] + 1;
>>     s->num_outputs = scan.file_max[TGSI_FILE_OUTPUT] + 1;
>> diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h
>> index bedcc0d..629c32f 100644
>> --- a/src/glsl/nir/nir.h
>> +++ b/src/glsl/nir/nir.h
>> @@ -1510,6 +1510,20 @@ typedef struct nir_shader_info {
>>     /** Was this shader linked with any transform feedback varyings? */
>>     bool has_transform_feedback_varyings;
>>
>> +   /**
>> +    * Special hack for tgsi_to_nir.  Due to limitations in TGSI, when
>> +    * there is indirect addressing of the input file, we don't actually
>> +    * know which inputs are part of an array and which are not.  We
>> +    * cannot convert all the inputs to a single array (which maps to
>> +    * TGSI's IN[ADDR[0].x+n] semantics), since we need the varying-slot
>> +    * and interpolation information still.
>> +    *
>> +    * NOTE that tgsi_to_nir doesn't generate indirect output_store's,
>> +    * otherwise we would need a similar flag to indicate indirect
>> +    * output file addressing.
>> +    */
>> +   bool tgsi_hack_indirect_inputs;
>> +
>>     union {
>>        struct {
>>           /** The number of vertices recieves per input primitive */
>> --
>> 2.5.0
>>
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