[Mesa-dev] [PATCH 6/6] i965/vec4: Optimize predicate handling for any/all.

[Kenneth Graunke]

On Monday, November 30, 2015 03:32:11 PM Matt Turner wrote:
> For a select whose condition is any(v), instead of emitting
> 
>    cmp.nz.f0(8)    null<1>D        g1<0,4,1>D      0D
>    mov(8)          g7<1>.xUD       0x00000000UD
>    (+f0.any4h) mov(8) g7<1>.xUD    0xffffffffUD
>    cmp.nz.f0(8)    null<1>D        g7<4,4,1>.xD    0D
>    (+f0) sel(8)    g8<1>UD         g4<4,4,1>UD     g3<4,4,1>UD
> 
> we now emit
> 
>    cmp.nz.f0(8)    null<1>D        g1<0,4,1>D      0D
>    (+f0.any4h) sel(8) g9<1>UD      g4<4,4,1>UD     g3<4,4,1>UD
> ---
>  src/mesa/drivers/dri/i965/brw_vec4.h       |  2 +
>  src/mesa/drivers/dri/i965/brw_vec4_nir.cpp | 96 ++++++++++++++++++++++++------
>  2 files changed, 80 insertions(+), 18 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4.h b/src/mesa/drivers/dri/i965/brw_vec4.h
> index 25b1139..ae98325 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4.h
> +++ b/src/mesa/drivers/dri/i965/brw_vec4.h
> @@ -313,6 +313,8 @@ public:
>  
>     bool is_high_sampler(src_reg sampler);
>  
> +   bool optimize_predicate(nir_alu_instr *instr, enum brw_predicate *predicate);
> +
>     virtual void emit_nir_code();
>     virtual void nir_setup_inputs();
>     virtual void nir_setup_uniforms();
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp b/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp
> index 6666457..f734171 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp
> @@ -928,6 +928,62 @@ brw_conditional_for_nir_comparison(nir_op op)
>     }
>  }
>  
> +bool
> +vec4_visitor::optimize_predicate(nir_alu_instr *instr,
> +                                 enum brw_predicate *predicate)
> +{
> +   if (!instr->src[0].src.is_ssa ||
> +       !instr->src[0].src.ssa->parent_instr)

I think that parent_instr will never be non-NULL.

With that fixed (or not),
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

> +      return false;
> +
> +   if (instr->src[0].src.ssa->parent_instr->type != nir_instr_type_alu)
> +      return false;
> +
> +   nir_alu_instr *cmp_instr =
> +      nir_instr_as_alu(instr->src[0].src.ssa->parent_instr);
> +
> +   switch (cmp_instr->op) {
> +   case nir_op_bany_fnequal2:
> +   case nir_op_bany_inequal2:
> +   case nir_op_bany_fnequal3:
> +   case nir_op_bany_inequal3:
> +   case nir_op_bany_fnequal4:
> +   case nir_op_bany_inequal4:
> +      *predicate = BRW_PREDICATE_ALIGN16_ANY4H;
> +      break;
> +   case nir_op_ball_fequal2:
> +   case nir_op_ball_iequal2:
> +   case nir_op_ball_fequal3:
> +   case nir_op_ball_iequal3:
> +   case nir_op_ball_fequal4:
> +   case nir_op_ball_iequal4:
> +      *predicate = BRW_PREDICATE_ALIGN16_ALL4H;
> +      break;
> +   default:
> +      return false;
> +   }
> +
> +   unsigned size_swizzle =
> +      brw_swizzle_for_size(nir_op_infos[cmp_instr->op].input_sizes[0]);
> +
> +   src_reg op[2];
> +   assert(nir_op_infos[cmp_instr->op].num_inputs == 2);
> +   for (unsigned i = 0; i < 2; i++) {
> +      op[i] = get_nir_src(cmp_instr->src[i].src,
> +                          nir_op_infos[cmp_instr->op].input_types[i], 4);
> +      unsigned base_swizzle =
> +         brw_swizzle_for_nir_swizzle(cmp_instr->src[i].swizzle);
> +      op[i].swizzle = brw_compose_swizzle(size_swizzle, base_swizzle);
> +      op[i].abs = cmp_instr->src[i].abs;
> +      op[i].negate = cmp_instr->src[i].negate;
> +   }
> +
> +   emit(CMP(dst_null_d(), op[0], op[1],
> +            brw_conditional_for_nir_comparison(cmp_instr->op)));
> +
> +   return true;
> +}
> +
>  void
>  vec4_visitor::nir_emit_alu(nir_alu_instr *instr)
>  {
> @@ -1418,25 +1474,29 @@ vec4_visitor::nir_emit_alu(nir_alu_instr *instr)
>        break;
>  
>     case nir_op_bcsel:
> -      emit(CMP(dst_null_d(), op[0], brw_imm_d(0), BRW_CONDITIONAL_NZ));
> -      inst = emit(BRW_OPCODE_SEL, dst, op[1], op[2]);
> -      switch (dst.writemask) {
> -      case WRITEMASK_X:
> -         inst->predicate = BRW_PREDICATE_ALIGN16_REPLICATE_X;
> -         break;
> -      case WRITEMASK_Y:
> -         inst->predicate = BRW_PREDICATE_ALIGN16_REPLICATE_Y;
> -         break;
> -      case WRITEMASK_Z:
> -         inst->predicate = BRW_PREDICATE_ALIGN16_REPLICATE_Z;
> -         break;
> -      case WRITEMASK_W:
> -         inst->predicate = BRW_PREDICATE_ALIGN16_REPLICATE_W;
> -         break;
> -      default:
> -         inst->predicate = BRW_PREDICATE_NORMAL;
> -         break;
> +      enum brw_predicate predicate;
> +      if (!optimize_predicate(instr, &predicate)) {
> +         emit(CMP(dst_null_d(), op[0], brw_imm_d(0), BRW_CONDITIONAL_NZ));
> +         switch (dst.writemask) {
> +         case WRITEMASK_X:
> +            predicate = BRW_PREDICATE_ALIGN16_REPLICATE_X;
> +            break;
> +         case WRITEMASK_Y:
> +            predicate = BRW_PREDICATE_ALIGN16_REPLICATE_Y;
> +            break;
> +         case WRITEMASK_Z:
> +            predicate = BRW_PREDICATE_ALIGN16_REPLICATE_Z;
> +            break;
> +         case WRITEMASK_W:
> +            predicate = BRW_PREDICATE_ALIGN16_REPLICATE_W;
> +            break;
> +         default:
> +            predicate = BRW_PREDICATE_NORMAL;
> +            break;
> +         }
>        }
> +      inst = emit(BRW_OPCODE_SEL, dst, op[1], op[2]);
> +      inst->predicate = predicate;
>        break;
>  
>     case nir_op_fdot_replicated2:
> 
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