[Mesa-dev] [PATCH 2/2] ac: use the common helper ac_apply_fmask_to_sample

[Samuel Pitoiset]

On 4/12/19 5:04 PM, Marek Olšák wrote:
>
> On Thu, Apr 11, 2019 at 3:15 AM Samuel Pitoiset 
> <samuel.pitoiset at gmail.com <mailto:samuel.pitoiset at gmail.com>> wrote:
>
>
>     On 4/11/19 3:30 AM, Marek Olšák wrote:
>     > From: Marek Olšák <marek.olsak at amd.com <mailto:marek.olsak at amd.com>>
>     >
>     > ---
>     >   src/amd/common/ac_nir_to_llvm.c | 70
>     +++------------------------------
>     >   1 file changed, 5 insertions(+), 65 deletions(-)
>     >
>     > diff --git a/src/amd/common/ac_nir_to_llvm.c
>     b/src/amd/common/ac_nir_to_llvm.c
>     > index 3d2f738edec..3abde6e0969 100644
>     > --- a/src/amd/common/ac_nir_to_llvm.c
>     > +++ b/src/amd/common/ac_nir_to_llvm.c
>     > @@ -2323,92 +2323,32 @@ static int
>     image_type_to_components_count(enum glsl_sampler_dim dim, bool array)
>     >       case GLSL_SAMPLER_DIM_SUBPASS:
>     >               return 2;
>     >       case GLSL_SAMPLER_DIM_SUBPASS_MS:
>     >               return 3;
>     >       default:
>     >               break;
>     >       }
>     >       return 0;
>     >   }
>     >
>     > -
>     > -/* Adjust the sample index according to FMASK.
>     > - *
>     > - * For uncompressed MSAA surfaces, FMASK should return 0x76543210,
>     > - * which is the identity mapping. Each nibble says which
>     physical sample
>     > - * should be fetched to get that sample.
>     > - *
>     > - * For example, 0x11111100 means there are only 2 samples
>     stored and
>     > - * the second sample covers 3/4 of the pixel. When reading
>     samples 0
>     > - * and 1, return physical sample 0 (determined by the first two 0s
>     > - * in FMASK), otherwise return physical sample 1.
>     > - *
>     > - * The sample index should be adjusted as follows:
>     > - *   sample_index = (fmask >> (sample_index * 4)) & 0xF;
>     > - */
>     >   static LLVMValueRef adjust_sample_index_using_fmask(struct
>     ac_llvm_context *ctx,
>     >  LLVMValueRef coord_x, LLVMValueRef coord_y,
>     >  LLVMValueRef coord_z,
>     >  LLVMValueRef sample_index,
>     >  LLVMValueRef fmask_desc_ptr)
>     >   {
>     > -     struct ac_image_args args = {0};
>     > -     LLVMValueRef res;
>     > +     unsigned sample_chan = coord_z ? 3 : 2;
>     > +     LLVMValueRef addr[4] = {coord_x, coord_y, coord_z};
>     > +     addr[sample_chan] = sample_index;
>     >
>     > -     args.coords[0] = coord_x;
>     > -     args.coords[1] = coord_y;
>     > -     if (coord_z)
>     > -             args.coords[2] = coord_z;
>     > -
>     > -     args.opcode = ac_image_load;
>     > -     args.dim = coord_z ? ac_image_2darray : ac_image_2d;
>     > -     args.resource = fmask_desc_ptr;
>     > -     args.dmask = 0xf;
>     > -     args.attributes = AC_FUNC_ATTR_READNONE;
>     > -
>     > -     res = ac_build_image_opcode(ctx, &args);
>     > -
>     > -     res = ac_to_integer(ctx, res);
>     > -     LLVMValueRef four = LLVMConstInt(ctx->i32, 4, false);
>     > -     LLVMValueRef F = LLVMConstInt(ctx->i32, 0xf, false);
>     > -
>     > -     LLVMValueRef fmask = LLVMBuildExtractElement(ctx->builder,
>     > -                                                  res,
>     > - ctx->i32_0, "");
>     > -
>     > -     LLVMValueRef sample_index4 =
>     > -             LLVMBuildMul(ctx->builder, sample_index, four, "");
>     > -     LLVMValueRef shifted_fmask =
>     > -             LLVMBuildLShr(ctx->builder, fmask, sample_index4, "");
>     > -     LLVMValueRef final_sample =
>     > -             LLVMBuildAnd(ctx->builder, shifted_fmask, F, "");
>
>     The only difference is the mask (ie. ac_apply_fmask_to_sample uses
>     0x7)
>     while this code uses 0xF.
>
>
> Yes.
>
>
>     According to the comment in that function, I assume 0x7 is the
>     correct
>     value?
>
>
> Yes, it's for EQAA. Only samples 0-7 can occur with MSAA. If EQAA is 
> used, 0x8 means the color of the sample is unknown, which is mapped to 
> sample 0 by the 0x7 mask.
Reviewed-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
>
> Marek
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