[Mesa-dev] [PATCH 1/2] gm107/ir: make use of FADD32I for all immediates

[Ilia Mirkin]

On Mon, Jun 27, 2016 at 6:05 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
> On Mon, Jun 27, 2016 at 6:04 PM, Samuel Pitoiset
> <samuel.pitoiset at gmail.com> wrote:
>>
>>
>> On 06/28/2016 12:02 AM, Ilia Mirkin wrote:
>>>
>>> This loses you saturation. Does the target account for this?
>>
>>
>> No saturate flag for FADD32I.
>
> That's not what I asked.

Specifically look at this code:

bool
TargetNVC0::isSatSupported(const Instruction *insn) const
{
   if (insn->op == OP_CVT)
      return true;
   if (!(opInfo[insn->op].dstMods & NV50_IR_MOD_SAT))
      return false;

   if (insn->dType == TYPE_U32)
      return (insn->op == OP_ADD) || (insn->op == OP_MAD);

   // add f32 LIMM cannot saturate
   if (insn->op == OP_ADD && insn->sType == TYPE_F32) {
      if (insn->getSrc(1)->asImm() &&
          insn->getSrc(1)->reg.data.u32 & 0xfff)
         return false;
   }

Note how it will say that sat is supported for SIMMs with FADD? So the
compiler will generate those ops, but then the emitter won't be able
to handle it.