[Mesa-dev] [PATCH] r600g: fix color exports when we have no CBs

[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 <vadimgirlin at 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;
-- 
1.8.3.1