[Mesa-dev] [PATCH v2 8/9] nvc0/ir: Implement TGSI_OPCODE_BALLOT and TGSI_OPCODE_READ_*

[Boyan Ding]

2017-04-10 9:54 GMT+08:00 Ilia Mirkin <imirkin at alum.mit.edu>:
> On Sun, Apr 9, 2017 at 8:58 PM, Boyan Ding <boyan.j.ding at gmail.com> wrote:
>> ---
>>  .../drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp  | 28 ++++++++++++++++++++++
>>  1 file changed, 28 insertions(+)
>>
>> diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
>> index 1bd01a9a32..2ce6f29905 100644
>> --- a/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
>> +++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
>> @@ -978,6 +978,10 @@ static nv50_ir::operation translateOpcode(uint opcode)
>>     NV50_IR_OPCODE_CASE(VOTE_ANY, VOTE);
>>     NV50_IR_OPCODE_CASE(VOTE_EQ, VOTE);
>>
>> +   NV50_IR_OPCODE_CASE(BALLOT, VOTE);
>> +   NV50_IR_OPCODE_CASE(READ_INVOC, SHFL);
>> +   NV50_IR_OPCODE_CASE(READ_FIRST, SHFL);
>> +
>>     NV50_IR_OPCODE_CASE(END, EXIT);
>>
>>     default:
>> @@ -3431,6 +3435,30 @@ Converter::handleInstruction(const struct tgsi_full_instruction *insn)
>>           mkCvt(OP_CVT, TYPE_U32, dst0[c], TYPE_U8, val0);
>>        }
>>        break;
>> +   case TGSI_OPCODE_BALLOT:
>> +      val0 = new_LValue(func, FILE_PREDICATE);
>> +      mkCmp(OP_SET, CC_NE, TYPE_U32, val0, TYPE_U32, fetchSrc(0, 0), zero);
>> +      mkOp1(op, TYPE_U32, dst0[0], val0)->subOp = NV50_IR_SUBOP_VOTE_ANY;
>> +      mkMov(dst0[1], zero, TYPE_U32);
>
> Check that dst[n] isn't masked though before writing to it.
>
>> +      break;
>> +   case TGSI_OPCODE_READ_FIRST:
>> +      // ReadFirstInvocationARB(src) is implemented as
>> +      // ReadInvocationARB(src, findLSB(ballot(true)))
>> +      val0 = getScratch();
>> +      mkOp1(OP_VOTE, TYPE_U32, val0, mkImm(1))->subOp = NV50_IR_SUBOP_VOTE_ANY;
>> +      mkOp2(OP_EXTBF, TYPE_U32, val0, val0, mkImm(0x2000))
>> +         ->subOp = NV50_IR_SUBOP_EXTBF_REV;
>> +      mkOp1(OP_BFIND, TYPE_U32, val0, val0)->subOp = NV50_IR_SUBOP_BFIND_SAMT;
>> +      src1 = val0;
>> +      /* fallthrough */
>
> You could, of course, do this as:
>
> if (false)
>
>> +   case TGSI_OPCODE_READ_INVOC:
>> +      if (tgsi.getOpcode() == TGSI_OPCODE_READ_INVOC)
>
> And then remove this if statement. (Ain't C fun.)
>
> But don't actually do that :) I'm more pointing it out due to the crazy factor.

Well, I didn't even think of that ;) But I surely won't take it.

>
> I really do hate that if for somewhat irrational reasons though...
> can't think of a clean way of getting rid of it. Oh well.

Yeah, the 'if' here isnt really great. However, without that, the only
way I could come up with will cause duplication which is even worse.

>
>> +         src1 = fetchSrc(1, 0);
>> +      FOR_EACH_DST_ENABLED_CHANNEL(0, c, tgsi) {
>> +         geni = mkOp3(op, dstTy, dst0[c], fetchSrc(0, c), src1, mkImm(0x1f));
>> +         geni->subOp = NV50_IR_SUBOP_SHFL_IDX;
>> +      }
>> +      break;
>>     case TGSI_OPCODE_CLOCK:
>>        // Stick the 32-bit clock into the high dword of the logical result.
>>        if (!tgsi.getDst(0).isMasked(0))
>> --
>> 2.12.1
>>
>> _______________________________________________
>> mesa-dev mailing list
>> mesa-dev at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/mesa-dev