Not that I'm qualified to review r600 code, but couldn't you create
different shader variants depending on whether you need alpha test? At
least I would assume shader exports aren't free.
Roland
Am 27.08.2013 19:56, schrieb Vadim Girlin:
> We need to export at least one color if the shader writes it,
> even when nr_cbufs==0.
>
> Signed-off-by: Vadim Girlin <vadimgir...@gmail.com>
> ---
>
> Tested on evergreen with multiple combinations of backends - no regressions,
> fixes some tests:
>
> default - fixes fb-alphatest-nocolor and fb_alphatest-nocolor-ff
> default+sb - fixes fb-alphatest-nocolor and fb_alphatest-nocolor-ff
> llvm - fixes about 25 tests related to depth/stencil
> llvm+sb - fixes about 300 tests (llvm's depth/stencil issues and
> regressions cased by reordering of exports in sb)
>
> With this patch, there are no regressions with default+sb vs default.
> There is one regression with llvm+sb vs llvm - fs-texturegrad-miplevels,
> AFAICS it's a problem with llvm backend uncovered by sb - SET_GRADIENTS_V/H
> instructions are not placed in the same TEX clause with corresponding
> SAMPLE_G.
>
> src/gallium/drivers/r600/r600_shader.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/src/gallium/drivers/r600/r600_shader.c
> b/src/gallium/drivers/r600/r600_shader.c
> index 300b5c4..f7eab76 100644
> --- a/src/gallium/drivers/r600/r600_shader.c
> +++ b/src/gallium/drivers/r600/r600_shader.c
> @@ -918,6 +918,7 @@ static int r600_shader_from_tgsi(struct r600_screen
> *rscreen,
> unsigned opcode;
> int i, j, k, r = 0;
> int next_pos_base = 60, next_param_base = 0;
> + int max_color_exports = MAX2(key.nr_cbufs, 1);
> /* Declarations used by llvm code */
> bool use_llvm = false;
> bool indirect_gprs;
> @@ -1130,7 +1131,7 @@ static int r600_shader_from_tgsi(struct r600_screen
> *rscreen,
> radeon_llvm_ctx.face_gpr = ctx.face_gpr;
> radeon_llvm_ctx.r600_inputs = ctx.shader->input;
> radeon_llvm_ctx.r600_outputs = ctx.shader->output;
> - radeon_llvm_ctx.color_buffer_count = MAX2(key.nr_cbufs , 1);
> + radeon_llvm_ctx.color_buffer_count = max_color_exports;
> radeon_llvm_ctx.chip_class = ctx.bc->chip_class;
> radeon_llvm_ctx.fs_color_all = shader->fs_write_all &&
> (rscreen->chip_class >= EVERGREEN);
> radeon_llvm_ctx.stream_outputs = &so;
> @@ -1440,7 +1441,7 @@ static int r600_shader_from_tgsi(struct r600_screen
> *rscreen,
> case TGSI_PROCESSOR_FRAGMENT:
> if (shader->output[i].name == TGSI_SEMANTIC_COLOR) {
> /* never export more colors than the number of
> CBs */
> - if (shader->output[i].sid >= key.nr_cbufs) {
> + if (shader->output[i].sid >= max_color_exports)
> {
> /* skip export */
> j--;
> continue;
> @@ -1450,7 +1451,7 @@ static int r600_shader_from_tgsi(struct r600_screen
> *rscreen,
> output[j].type =
> V_SQ_CF_ALLOC_EXPORT_WORD0_SQ_EXPORT_PIXEL;
> shader->nr_ps_color_exports++;
> if (shader->fs_write_all &&
> (rscreen->chip_class >= EVERGREEN)) {
> - for (k = 1; k < key.nr_cbufs; k++) {
> + for (k = 1; k < max_color_exports; k++)
> {
> j++;
> memset(&output[j], 0,
> sizeof(struct r600_bytecode_output));
> output[j].gpr =
> shader->output[i].gpr;
>
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