[Mesa-dev] [PATCH v2 11/13] nvc0/ir: do not lower shared+atomics on GM107+

[Samuel Pitoiset]

On 04/01/2016 07:44 AM, Ilia Mirkin wrote:
>
> On Mar 31, 2016 12:09 PM, "Samuel Pitoiset" <samuel.pitoiset at gmail.com
> <mailto:samuel.pitoiset at gmail.com>> wrote:
>  >
>  > For Maxwell, the ATOMS instruction can be used to perform atomic
>  > operations on shared memory instead of this load/store lowering pass.
>  >
>  > Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com
> <mailto:samuel.pitoiset at gmail.com>>
>  > ---
>  >  .../nouveau/codegen/nv50_ir_lowering_nvc0.cpp        | 20
> +++++++++++++-------
>  >  1 file changed, 13 insertions(+), 7 deletions(-)
>  >
>  > diff --git
> a/src/gallium/drivers/nouveau/codegen/nv50_ir_lowering_nvc0.cpp
> b/src/gallium/drivers/nouveau/codegen/nv50_ir_lowering_nvc0.cpp
>  > index 7e6c87a..83e753e 100644
>  > --- a/src/gallium/drivers/nouveau/codegen/nv50_ir_lowering_nvc0.cpp
>  > +++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_lowering_nvc0.cpp
>  > @@ -1294,10 +1294,14 @@ NVC0LoweringPass::handleATOM(Instruction *atom)
>  >        sv = SV_LBASE;
>  >        break;
>  >     case FILE_MEMORY_SHARED:
>  > -      if (targ->getChipset() >= NVISA_GK104_CHIPSET) {
>  > -         handleSharedATOMNVE4(atom);
>  > -      } else {
>  > -         handleSharedATOM(atom);
>  > +      if (targ->getChipset() < NVISA_GM107_CHIPSET) {
>  > +         // For Fermi/Kepler, we have to use ld lock/st unlock to
> perform
>  > +         // atomic operations on shared memory. For Maxwell, ATOMS
> is enough.
>  > +         if (targ->getChipset() >= NVISA_GK104_CHIPSET) {
>  > +            handleSharedATOMNVE4(atom);
>  > +         } else {
>  > +            handleSharedATOM(atom);
>  > +         }
>  >        }
>
> Or, with fewer branches...
>
> If (<nve4) do nvc0 thing
> Else if (<gm107) do nve4 thing
>
> Which will drop the outer if, making it more comprehensible.

Looks better, thanks!

>
>  >        return true;
>  >     default:
>  > @@ -1326,9 +1330,11 @@ NVC0LoweringPass::handleATOM(Instruction *atom)
>  >  bool
>  >  NVC0LoweringPass::handleCasExch(Instruction *cas, bool needCctl)
>  >  {
>  > -   if (cas->src(0).getFile() == FILE_MEMORY_SHARED) {
>  > -      // ATOM_CAS and ATOM_EXCH are handled in handleSharedATOM().
>  > -      return false;
>  > +   if (targ->getChipset() < NVISA_GM107_CHIPSET) {
>  > +      if (cas->src(0).getFile() == FILE_MEMORY_SHARED) {
>  > +         // ATOM_CAS and ATOM_EXCH are handled in handleSharedATOM().
>  > +         return false;
>  > +      }
>  >     }
>  >
>  >     if (cas->subOp != NV50_IR_SUBOP_ATOM_CAS &&
>  > --
>  > 2.7.4
>  >
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>

-- 
-Samuel