On 24.08.2013 11:44, Christian König wrote: > Am 24.08.2013 03:30, schrieb Vadim Girlin: >> Currently llvm backend always exports at least one color in pixel >> shader even if no color buffers are enabled. With depth/stencil exports >> this can result in the following code: >> >> EXPORT PIXEL 0 R0.xyzw VPM >> EXPORT PIXEL 61 R1.x___ VPM >> EXPORT_DONE PIXEL 61 R0._x__ VPM EOP >> >> AFAIU with zero color buffers no memory is reserved for colors in the >> export >> ring and all exports in this example actually write to the same >> location. >> The code above still works fine in this particular case, because correct >> values are written last, but reordering can break it (especially with SB >> which tends to reorder the exports). >> >> Signed-off-by: Vadim Girlin <vadimgir...@gmail.com> > > I briefly remember that we needed at least one color export otherwise > the GPU might hang, but I'm not 100% sure of that. >
If there are no color buffers bound but the original shader writes color 0, you still have to export it to keep the alpha test working ... > Marek and Alex should probably also take a look on this before we > commit it. > > Christian. > >> --- >> >> This fixes regressions with LLVM+SB, so I consider it as a prerequisite >> for enabling SB by default. Also it fixes some issues with LLVM >> backend alone. >> Tested on evergreen only (I don't have other hw), needs testing on >> pre-evergreen GPUs. >> >> src/gallium/drivers/r600/r600_llvm.c | 2 +- >> src/gallium/drivers/r600/r600_shader.c | 2 +- >> 2 files changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/src/gallium/drivers/r600/r600_llvm.c >> b/src/gallium/drivers/r600/r600_llvm.c >> index 03a68e4..d2f4aff 100644 >> --- a/src/gallium/drivers/r600/r600_llvm.c >> +++ b/src/gallium/drivers/r600/r600_llvm.c >> @@ -333,8 +333,8 @@ static void llvm_emit_epilogue(struct >> lp_build_tgsi_context * bld_base) >> } else if (ctx->type == TGSI_PROCESSOR_FRAGMENT) { >> switch (ctx->r600_outputs[i].name) { >> case TGSI_SEMANTIC_COLOR: >> - has_color = true; >> if ( color_count < ctx->color_buffer_count) { >> + has_color = true; >> LLVMValueRef args[3]; >> args[0] = output; >> if (ctx->fs_color_all) { >> diff --git a/src/gallium/drivers/r600/r600_shader.c >> b/src/gallium/drivers/r600/r600_shader.c >> index fb766c4..85f8469 100644 >> --- a/src/gallium/drivers/r600/r600_shader.c >> +++ b/src/gallium/drivers/r600/r600_shader.c >> @@ -1130,7 +1130,7 @@ 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 = key.nr_cbufs; >> 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; > > _______________________________________________ > mesa-dev mailing list > mesa-dev@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/mesa-dev _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev