radeonsi: implement SAMPLEPOS fragment shader input

The sample positions are read from a constant buffer.

5 files changed, 76 insertions, 0 deletions

diff --git a/src/gallium/drivers/radeon/cayman_msaa.c b/src/gallium/drivers/radeon/cayman_msaa.c
index 8727f3e2359..47fc5c497f1 100644
--- a/src/gallium/drivers/radeon/cayman_msaa.c
+++ b/src/gallium/drivers/radeon/cayman_msaa.c
@@ -123,6 +123,23 @@ void cayman_get_sample_position(struct pipe_context *ctx, unsigned sample_count,
 	}
 }
 
+void cayman_init_msaa(struct pipe_context *ctx)
+{
+	struct r600_common_context *rctx = (struct r600_common_context*)ctx;
+	int i;
+
+	cayman_get_sample_position(ctx, 1, 0, rctx->sample_locations_1x[0]);
+
+	for (i = 0; i < 2; i++)
+		cayman_get_sample_position(ctx, 2, i, rctx->sample_locations_2x[i]);
+	for (i = 0; i < 4; i++)
+		cayman_get_sample_position(ctx, 4, i, rctx->sample_locations_4x[i]);
+	for (i = 0; i < 8; i++)
+		cayman_get_sample_position(ctx, 8, i, rctx->sample_locations_8x[i]);
+	for (i = 0; i < 16; i++)
+		cayman_get_sample_position(ctx, 16, i, rctx->sample_locations_16x[i]);
+}
+
 void cayman_emit_msaa_sample_locs(struct radeon_winsys_cs *cs, int nr_samples)
 {
 	switch (nr_samples) {
diff --git a/src/gallium/drivers/radeon/r600_pipe_common.c b/src/gallium/drivers/radeon/r600_pipe_common.c
index 70c4d1adefb..4c6cf0e60c1 100644
--- a/src/gallium/drivers/radeon/r600_pipe_common.c
+++ b/src/gallium/drivers/radeon/r600_pipe_common.c
@@ -154,6 +154,7 @@ bool r600_common_context_init(struct r600_common_context *rctx,
 	r600_init_context_texture_functions(rctx);
 	r600_streamout_init(rctx);
 	r600_query_init(rctx);
+	cayman_init_msaa(&rctx->b);
 
 	rctx->allocator_so_filled_size = u_suballocator_create(&rctx->b, 4096, 4,
 							       0, PIPE_USAGE_DEFAULT, TRUE);
diff --git a/src/gallium/drivers/radeon/r600_pipe_common.h b/src/gallium/drivers/radeon/r600_pipe_common.h
index b7e4e65cf11..d82adf5d387 100644
--- a/src/gallium/drivers/radeon/r600_pipe_common.h
+++ b/src/gallium/drivers/radeon/r600_pipe_common.h
@@ -357,6 +357,15 @@ struct r600_common_context {
 	boolean				saved_render_cond_cond;
 	unsigned			saved_render_cond_mode;
 
+	/* MSAA sample locations.
+	 * The first index is the sample index.
+	 * The second index is the coordinate: X, Y. */
+	float				sample_locations_1x[1][2];
+	float				sample_locations_2x[2][2];
+	float				sample_locations_4x[4][2];
+	float				sample_locations_8x[8][2];
+	float				sample_locations_16x[16][2];
+
 	/* Copy one resource to another using async DMA. */
 	void (*dma_copy)(struct pipe_context *ctx,
 			 struct pipe_resource *dst,
@@ -472,6 +481,7 @@ extern const uint32_t eg_sample_locs_4x[4];
 extern const unsigned eg_max_dist_4x;
 void cayman_get_sample_position(struct pipe_context *ctx, unsigned sample_count,
 				unsigned sample_index, float *out_value);
+void cayman_init_msaa(struct pipe_context *ctx);
 void cayman_emit_msaa_sample_locs(struct radeon_winsys_cs *cs, int nr_samples);
 void cayman_emit_msaa_config(struct radeon_winsys_cs *cs, int nr_samples,
 			     int ps_iter_samples);
diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
index d021caaa6c4..6818106ece7 100644
--- a/src/gallium/drivers/radeonsi/si_shader.c
+++ b/src/gallium/drivers/radeonsi/si_shader.c
@@ -557,6 +557,8 @@ static void declare_system_value(
 {
 	struct si_shader_context *si_shader_ctx =
 		si_shader_context(&radeon_bld->soa.bld_base);
+	struct lp_build_context *uint_bld = &radeon_bld->soa.bld_base.uint_bld;
+	struct gallivm_state *gallivm = &radeon_bld->gallivm;
 	LLVMValueRef value = 0;
 
 	switch (decl->Semantic.Name) {
@@ -574,6 +576,27 @@ static void declare_system_value(
 		value = get_sample_id(radeon_bld);
 		break;
 
+	case TGSI_SEMANTIC_SAMPLEPOS:
+	{
+		LLVMBuilderRef builder = gallivm->builder;
+		LLVMValueRef desc = LLVMGetParam(si_shader_ctx->radeon_bld.main_fn, SI_PARAM_CONST);
+		LLVMValueRef buf_index = lp_build_const_int32(gallivm, NUM_PIPE_CONST_BUFFERS);
+		LLVMValueRef resource = build_indexed_load(si_shader_ctx, desc, buf_index);
+
+		/* offset = sample_id * 8  (8 = 2 floats containing samplepos.xy) */
+		LLVMValueRef offset0 = lp_build_mul_imm(uint_bld, get_sample_id(radeon_bld), 8);
+		LLVMValueRef offset1 = LLVMBuildAdd(builder, offset0, lp_build_const_int32(gallivm, 4), "");
+
+		LLVMValueRef pos[4] = {
+			load_const(builder, resource, offset0, radeon_bld->soa.bld_base.base.elem_type),
+			load_const(builder, resource, offset1, radeon_bld->soa.bld_base.base.elem_type),
+			lp_build_const_float(gallivm, 0),
+			lp_build_const_float(gallivm, 0)
+		};
+		value = lp_build_gather_values(gallivm, pos, 4);
+		break;
+	}
+
 	default:
 		assert(!"unknown system value");
 		return;
diff --git a/src/gallium/drivers/radeonsi/si_state.c b/src/gallium/drivers/radeonsi/si_state.c
index c08d7034c55..b85a4594156 100644
--- a/src/gallium/drivers/radeonsi/si_state.c
+++ b/src/gallium/drivers/radeonsi/si_state.c
@@ -1859,6 +1859,7 @@ static void si_set_framebuffer_state(struct pipe_context *ctx,
 				     const struct pipe_framebuffer_state *state)
 {
 	struct si_context *sctx = (struct si_context *)ctx;
+	struct pipe_constant_buffer constbuf = {0};
 	struct r600_surface *surf = NULL;
 	struct r600_texture *rtex;
 	int i;
@@ -1924,6 +1925,30 @@ static void si_set_framebuffer_state(struct pipe_context *ctx,
 	sctx->framebuffer.atom.num_dw += 18; /* MSAA sample locations */
 	sctx->framebuffer.atom.dirty = true;
 	sctx->msaa_config.dirty = true;
+
+	/* Set sample locations as fragment shader constants. */
+	switch (sctx->framebuffer.nr_samples) {
+	case 1:
+		constbuf.user_buffer = sctx->b.sample_locations_1x;
+		break;
+	case 2:
+		constbuf.user_buffer = sctx->b.sample_locations_2x;
+		break;
+	case 4:
+		constbuf.user_buffer = sctx->b.sample_locations_4x;
+		break;
+	case 8:
+		constbuf.user_buffer = sctx->b.sample_locations_8x;
+		break;
+	case 16:
+		constbuf.user_buffer = sctx->b.sample_locations_16x;
+		break;
+	default:
+		assert(0);
+	}
+	constbuf.buffer_size = sctx->framebuffer.nr_samples * 2 * 4;
+	ctx->set_constant_buffer(ctx, PIPE_SHADER_FRAGMENT,
+				 NUM_PIPE_CONST_BUFFERS, &constbuf);
 }
 
 static void si_emit_framebuffer_state(struct si_context *sctx, struct r600_atom *atom)