[Mesa-dev] [PATCH v2 03/17] radeonsi: Fix handling of geometry shader output vertex ID

[Michel Dänzer]

From: Michel Dänzer <michel.daenzer at amd.com>

It needs to increment at shader runtime, not at shader compile time, as
the geometry shader can emit vertices in loops. LLVM automagically
converts the ID back to an immediate value if its value can be
determined at compile time.

Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>
---

v2: Drop excessive HAVE_LLVM preprocessor guards

 src/gallium/drivers/radeonsi/si_shader.c | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
index a04110b..8696d03 100644
--- a/src/gallium/drivers/radeonsi/si_shader.c
+++ b/src/gallium/drivers/radeonsi/si_shader.c
@@ -61,7 +61,6 @@ struct si_shader_context
 	struct si_pipe_shader *shader;
 	struct si_shader *gs_for_vs;
 	unsigned type; /* TGSI_PROCESSOR_* specifies the type of shader. */
-	unsigned gs_next_vertex;
 	int param_streamout_config;
 	int param_streamout_write_index;
 	int param_streamout_offset[4];
@@ -76,6 +75,7 @@ struct si_shader_context
 	LLVMValueRef *resources;
 	LLVMValueRef *samplers;
 	LLVMValueRef so_buffers[4];
+	LLVMValueRef gs_next_vertex;
 };
 
 static struct si_shader_context * si_shader_context(
@@ -1854,9 +1854,11 @@ static void si_llvm_emit_vertex(
 	struct lp_build_emit_data *emit_data)
 {
 	struct si_shader_context *si_shader_ctx = si_shader_context(bld_base);
+	struct lp_build_context *uint = &bld_base->uint_bld;
 	struct si_shader *shader = &si_shader_ctx->shader->shader;
 	struct gallivm_state *gallivm = bld_base->base.gallivm;
 	LLVMTypeRef i32 = LLVMInt32TypeInContext(gallivm->context);
+	LLVMValueRef gs_next_vertex;
 	LLVMValueRef t_list_ptr;
 	LLVMValueRef t_list;
 	LLVMValueRef args[2];
@@ -1882,20 +1884,22 @@ static void si_llvm_emit_vertex(
 	}
 
 	/* Write vertex attribute values to GSVS ring */
+	gs_next_vertex = LLVMBuildLoad(gallivm->builder, si_shader_ctx->gs_next_vertex, "");
 	for (i = 0; i < shader->noutput; i++) {
 		LLVMValueRef *out_ptr =
 			si_shader_ctx->radeon_bld.soa.outputs[shader->output[i].index];
 
 		for (chan = 0; chan < 4; chan++) {
 			LLVMValueRef out_val = LLVMBuildLoad(gallivm->builder, out_ptr[chan], "");
-			LLVMValueRef voffset =
-				lp_build_const_int32(gallivm,
-						     ((i * 4 + chan) *
-						      shader->gs_max_out_vertices +
-						      si_shader_ctx->gs_next_vertex) * 4);
 			LLVMValueRef soffset =
 				LLVMGetParam(si_shader_ctx->radeon_bld.main_fn,
 					     SI_PARAM_GS2VS_OFFSET);
+			LLVMValueRef voffset =
+				lp_build_const_int32(gallivm, (i * 4 + chan) *
+						     shader->gs_max_out_vertices);
+
+			voffset = lp_build_add(uint, voffset, gs_next_vertex);
+			voffset = lp_build_mul_imm(uint, voffset, 4);
 
 			out_val = LLVMBuildBitCast(gallivm->builder, out_val, i32, "");
 
@@ -1906,7 +1910,9 @@ static void si_llvm_emit_vertex(
 					    1, 0, 1, 1, 0);
 		}
 	}
-	si_shader_ctx->gs_next_vertex++;
+	gs_next_vertex = lp_build_add(uint, gs_next_vertex,
+				      lp_build_const_int32(gallivm, 1));
+	LLVMBuildStore(gallivm->builder, gs_next_vertex, si_shader_ctx->gs_next_vertex);
 
 	/* Signal vertex emission */
 	args[0] = lp_build_const_int32(gallivm, SENDMSG_GS_OP_EMIT | SENDMSG_GS);
@@ -2483,6 +2489,12 @@ int si_pipe_shader_create(
 		si_dump_streamout(&sel->so);
 	}
 
+	if (si_shader_ctx.type == TGSI_PROCESSOR_GEOMETRY) {
+		si_shader_ctx.gs_next_vertex =
+			lp_build_alloca(bld_base->base.gallivm,
+					bld_base->uint_bld.elem_type, "");
+	}
+
 	if (!lp_build_tgsi_llvm(bld_base, sel->tokens)) {
 		fprintf(stderr, "Failed to translate shader from TGSI to LLVM\n");
 		goto out;
-- 
1.8.5.3