3 files changed, 61 insertions, 9 deletions

diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
index 2b432244331..abe30e54a58 100644
--- a/src/gallium/drivers/radeonsi/si_shader.c
+++ b/src/gallium/drivers/radeonsi/si_shader.c
@@ -2281,6 +2281,26 @@ static void si_llvm_export_vs(struct lp_build_tgsi_context *bld_base,
 	for (i = 0; i < noutput; i++) {
 		semantic_name = outputs[i].name;
 		semantic_index = outputs[i].sid;
+		bool export_param = true;
+
+		switch (semantic_name) {
+		case TGSI_SEMANTIC_POSITION: /* ignore these */
+		case TGSI_SEMANTIC_PSIZE:
+		case TGSI_SEMANTIC_CLIPVERTEX:
+		case TGSI_SEMANTIC_EDGEFLAG:
+			break;
+		case TGSI_SEMANTIC_GENERIC:
+		case TGSI_SEMANTIC_CLIPDIST:
+			if (shader->key.opt.hw_vs.kill_outputs &
+			    (1ull << si_shader_io_get_unique_index(semantic_name, semantic_index)))
+				export_param = false;
+			break;
+		default:
+			if (shader->key.opt.hw_vs.kill_outputs2 &
+			    (1u << si_shader_io_get_unique_index2(semantic_name, semantic_index)))
+				export_param = false;
+			break;
+		}
 
 handle_semantic:
 		/* Select the correct target */
@@ -2304,6 +2324,8 @@ handle_semantic:
 			break;
 		case TGSI_SEMANTIC_COLOR:
 		case TGSI_SEMANTIC_BCOLOR:
+			if (!export_param)
+				continue;
 			target = V_008DFC_SQ_EXP_PARAM + param_count;
 			assert(i < ARRAY_SIZE(shader->info.vs_output_param_offset));
 			shader->info.vs_output_param_offset[i] = param_count;
@@ -2325,6 +2347,8 @@ handle_semantic:
 		case TGSI_SEMANTIC_FOG:
 		case TGSI_SEMANTIC_TEXCOORD:
 		case TGSI_SEMANTIC_GENERIC:
+			if (!export_param)
+				continue;
 			target = V_008DFC_SQ_EXP_PARAM + param_count;
 			assert(i < ARRAY_SIZE(shader->info.vs_output_param_offset));
 			shader->info.vs_output_param_offset[i] = param_count;
@@ -7083,7 +7107,7 @@ int si_compile_tgsi_shader(struct si_screen *sscreen,
 	si_init_shader_ctx(&ctx, sscreen, shader, tm);
 	ctx.separate_prolog = !is_monolithic;
 
-	memset(shader->info.vs_output_param_offset, 0xff,
+	memset(shader->info.vs_output_param_offset, EXP_PARAM_UNDEFINED,
 	       sizeof(shader->info.vs_output_param_offset));
 
 	shader->info.uses_instanceid = sel->info.uses_instanceid;
diff --git a/src/gallium/drivers/radeonsi/si_shader.h b/src/gallium/drivers/radeonsi/si_shader.h
index fc9c9131be8..aa37676f887 100644
--- a/src/gallium/drivers/radeonsi/si_shader.h
+++ b/src/gallium/drivers/radeonsi/si_shader.h
@@ -322,10 +322,6 @@ struct si_vs_prolog_bits {
 /* Common VS bits between the shader key and the epilog key. */
 struct si_vs_epilog_bits {
 	unsigned	export_prim_id:1; /* when PS needs it and GS is disabled */
-	/* TODO:
-	 * - skip layer, viewport, clipdist, and culldist parameter exports
-	 *   if PS doesn't read them
-	 */
 };
 
 /* Common TCS bits between the shader key and the epilog key. */
@@ -440,6 +436,8 @@ struct si_shader_key {
 	/* Optimization flags for asynchronous compilation only. */
 	union {
 		struct {
+			uint64_t	kill_outputs; /* "get_unique_index" bits */
+			uint32_t	kill_outputs2; /* "get_unique_index2" bits */
 			unsigned	clip_disable:1;
 		} hw_vs; /* HW VS (it can be VS, TES, GS) */
 	} opt;
@@ -468,6 +466,7 @@ enum {
 	EXP_PARAM_DEFAULT_VAL_0001,
 	EXP_PARAM_DEFAULT_VAL_1110,
 	EXP_PARAM_DEFAULT_VAL_1111,
+	EXP_PARAM_UNDEFINED = 255,
 };
 
 /* GCN-specific shader info. */
diff --git a/src/gallium/drivers/radeonsi/si_state_shaders.c b/src/gallium/drivers/radeonsi/si_state_shaders.c
index e4d8747c6fe..7834f8711b6 100644
--- a/src/gallium/drivers/radeonsi/si_state_shaders.c
+++ b/src/gallium/drivers/radeonsi/si_state_shaders.c
@@ -858,11 +858,35 @@ static void si_shader_selector_key_hw_vs(struct si_context *sctx,
 					 struct si_shader_selector *vs,
 					 struct si_shader_key *key)
 {
+	struct si_shader_selector *ps = sctx->ps_shader.cso;
+
 	key->opt.hw_vs.clip_disable =
 		sctx->queued.named.rasterizer->clip_plane_enable == 0 &&
 		(vs->info.clipdist_writemask ||
 		 vs->info.writes_clipvertex) &&
 		!vs->info.culldist_writemask;
+
+	/* Find out if PS is disabled. */
+	bool ps_disabled = ps == NULL;
+
+	/* Find out which VS outputs aren't used by the PS. */
+	uint64_t outputs_written = vs->outputs_written;
+	uint32_t outputs_written2 = vs->outputs_written2;
+	uint64_t inputs_read = 0;
+	uint32_t inputs_read2 = 0;
+
+	outputs_written &= ~0x3; /* ignore POSITION, PSIZE */
+
+	if (!ps_disabled) {
+		inputs_read = ps->inputs_read;
+		inputs_read2 = ps->inputs_read2;
+	}
+
+	uint64_t linked = outputs_written & inputs_read;
+	uint32_t linked2 = outputs_written2 & inputs_read2;
+
+	key->opt.hw_vs.kill_outputs = ~linked & outputs_written;
+	key->opt.hw_vs.kill_outputs2 = ~linked2 & outputs_written2;
 }
 
 /* Compute the key for the hw shader variant */
@@ -1785,11 +1809,16 @@ static unsigned si_get_ps_input_cntl(struct si_context *sctx,
 				/* The input is loaded from parameter memory. */
 				ps_input_cntl |= S_028644_OFFSET(offset);
 			} else if (!G_028644_PT_SPRITE_TEX(ps_input_cntl)) {
-				/* The input is a DEFAULT_VAL constant. */
-				assert(offset >= EXP_PARAM_DEFAULT_VAL_0000 &&
-				       offset <= EXP_PARAM_DEFAULT_VAL_1111);
+				if (offset == EXP_PARAM_UNDEFINED) {
+					/* This can happen with depth-only rendering. */
+					offset = 0;
+				} else {
+					/* The input is a DEFAULT_VAL constant. */
+					assert(offset >= EXP_PARAM_DEFAULT_VAL_0000 &&
+					       offset <= EXP_PARAM_DEFAULT_VAL_1111);
+					offset -= EXP_PARAM_DEFAULT_VAL_0000;
+				}
 
-				offset -= EXP_PARAM_DEFAULT_VAL_0000;
 				ps_input_cntl = S_028644_OFFSET(0x20) |
 						S_028644_DEFAULT_VAL(offset);
 			}