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

[Samuel Pitoiset]

On 4/11/19 3:30 AM, Marek Olšák wrote:
> From: Marek Olšák <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.

According to the comment in that function, I assume 0x7 is the correct 
value?

> -
> -	/* Don't rewrite the sample index if WORD1.DATA_FORMAT of the FMASK
> -	 * resource descriptor is 0 (invalid),
> -	 */
> -	LLVMValueRef fmask_desc =
> -		LLVMBuildBitCast(ctx->builder, fmask_desc_ptr,
> -				 ctx->v8i32, "");
> -
> -	LLVMValueRef fmask_word1 =
> -		LLVMBuildExtractElement(ctx->builder, fmask_desc,
> -					ctx->i32_1, "");
> -
> -	LLVMValueRef word1_is_nonzero =
> -		LLVMBuildICmp(ctx->builder, LLVMIntNE,
> -			      fmask_word1, ctx->i32_0, "");
> -
> -	/* Replace the MSAA sample index. */
> -	sample_index =
> -		LLVMBuildSelect(ctx->builder, word1_is_nonzero,
> -				final_sample, sample_index, "");
> -	return sample_index;
> +	ac_apply_fmask_to_sample(ctx, fmask_desc_ptr, addr, coord_z != NULL);
> +	return addr[sample_chan];
>   }
>   
>   static nir_deref_instr *get_image_deref(const nir_intrinsic_instr *instr)
>   {
>   	assert(instr->src[0].is_ssa);
>   	return nir_instr_as_deref(instr->src[0].ssa->parent_instr);
>   }
>   
>   static LLVMValueRef get_image_descriptor(struct ac_nir_context *ctx,
>                                            const nir_intrinsic_instr *instr,