[Mesa-dev] [PATCH 11/19] i965/fs: Use LOAD_PAYLOAD in emit_texture_gen7().

[Kenneth Graunke]

On 04/24/2014 08:40 AM, Matt Turner wrote:
> On Wed, Apr 23, 2014 at 11:19 PM, Kenneth Graunke <kenneth at whitecape.org> wrote:
>> On 04/18/2014 11:56 AM, Matt Turner wrote:
>>> ---
>>>  src/mesa/drivers/dri/i965/brw_fs_visitor.cpp | 135 +++++++++++++++------------
>>>  1 file changed, 73 insertions(+), 62 deletions(-)
>>>
>>> diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
>>> index 2aa3acd..91bbe0a 100644
>>> --- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
>>> +++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
>>> @@ -1257,8 +1257,11 @@ fs_visitor::emit_texture_gen7(ir_texture *ir, fs_reg dst, fs_reg coordinate,
>>>     int reg_width = dispatch_width / 8;
>>>     bool header_present = false;
>>>
>>> -   fs_reg payload = fs_reg(this, glsl_type::float_type);
>>> -   fs_reg next = payload;
>>> +   fs_reg *sources = ralloc_array(mem_ctx, fs_reg, MAX_SAMPLER_MESSAGE_SIZE);
>>> +   for (int i = 0; i < MAX_SAMPLER_MESSAGE_SIZE; i++) {
>>> +      sources[i] = fs_reg(this, glsl_type::float_type);
>>> +   }
>>> +   int length = 0;
>>>
>>>     if (ir->op == ir_tg4 || (ir->offset && ir->op != ir_txf) || sampler >= 16) {
>>>        /* For general texture offsets (no txf workaround), we need a header to
>>> @@ -1272,12 +1275,13 @@ fs_visitor::emit_texture_gen7(ir_texture *ir, fs_reg dst, fs_reg coordinate,
>>>         * need to offset the Sampler State Pointer in the header.
>>>         */
>>>        header_present = true;
>>> -      next.reg_offset++;
>>> +      sources[length] = reg_undef;
>>> +      length++;
>>>     }
>>
>> So...if you don't take the header_present = true path...then it looks
>> like the next thing (say, shadow_c) will land in sources[0], rather than
>> leaving sources[0] as BAD_FILE and putting the first part of the payload
>> in sources[1].
>>
>> Is sources[0] special and reserved for the header or isn't it?
> 
> It's the header if there is a header, and it's a regular source if
> there isn't a header. We can't make it always a header, because if the
> header doesn't exist we'll end up asking the register allocator for a
> set of registers one too large.

That seems reasonable.  But, if those are the semantics, I don't see any
reason for the lowering pass to handle src[0] specially.  It could just
loop from i = 0; i < inst->sources.  BAD_FILE should never happen.

[snip]
>>> @@ -1403,40 +1407,44 @@ fs_visitor::emit_texture_gen7(ir_texture *ir, fs_reg dst, fs_reg coordinate,
>>>     /* Set up the coordinate (except for cases where it was done above) */
>>>     if (ir->coordinate && !coordinate_done) {
>>>        for (int i = 0; i < ir->coordinate->type->vector_elements; i++) {
>>> -         emit(MOV(next, coordinate));
>>> +         emit(MOV(sources[length], coordinate));
>>>           coordinate.reg_offset++;
>>> -         next.reg_offset++;
>>> +         length++;
>>>        }
>>>     }
>>>
>>> +   fs_reg src_payload = fs_reg(this, glsl_type::float_type);
>>> +   virtual_grf_sizes[src_payload.reg] = length;
>>> +   emit(SHADER_OPCODE_LOAD_PAYLOAD, src_payload, sources, length);
>>> +
>>
>> I think I would prefer to see this called "payload", "msg_payload" or
>> simply "message".  There are enough things called src/sources/...
> 
> Right. I don't know, I thought "load the sources into the source
> payload" read pretty well. All of the other names suggest that they're
> already a contiguous set of registers.

But src_payload basically /is/ a contiguous set of registers.  At least,
it's a larger-than-size-1 VGRF which will be allocated to contiguous
registers.  This assembles an array of disjoint source registers into a
proper contiguous message.

But, if you don't like the suggestion, feel free to drop it.  It's just
a variable name. :)

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 836 bytes
Desc: OpenPGP digital signature
URL: <http://lists.freedesktop.org/archives/mesa-dev/attachments/20140424/2f1d6093/attachment-0001.sig>