[Mesa-dev] [PATCH] nv50/ir: do not perform global membar for shared memory

[Ilia Mirkin]

On Mon, Oct 24, 2016 at 10:29 AM, Samuel Pitoiset
<samuel.pitoiset at gmail.com> wrote:
> Shared memory is local to CTA, thus we should only wait for
> prior memory writes which are visible to other threads in
> the same CTA, and not at global level. This should speedup
> compute shaders which use shared memory.
>
> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
> ---
>  src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> 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 b47fc49..621a468 100644
> --- a/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
> +++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
> @@ -3561,12 +3561,15 @@ Converter::handleInstruction(const struct tgsi_full_instruction *insn)
>        geni->subOp = tgsi::opcodeToSubOp(tgsi.getOpcode());
>        break;
>     case TGSI_OPCODE_MEMBAR:
> +   {
> +      uint32_t level = tgsi.getSrc(0).getValueU32(0, info);
>        geni = mkOp(OP_MEMBAR, TYPE_NONE, NULL);
>        geni->fixed = 1;
> -      if (tgsi.getSrc(0).getValueU32(0, info) & TGSI_MEMBAR_THREAD_GROUP)
> +      if ((level & TGSI_MEMBAR_THREAD_GROUP) || level == TGSI_MEMBAR_SHARED)

Probably just level & (A | B)

>           geni->subOp = NV50_IR_SUBOP_MEMBAR(M, CTA);
>        else
>           geni->subOp = NV50_IR_SUBOP_MEMBAR(M, GL);
> +   }
>        break;
>     case TGSI_OPCODE_ATOMUADD:
>     case TGSI_OPCODE_ATOMXCHG:
> --
> 2.10.1
>
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