Mesa (master): radv: do not emit unnecessary ES output stores

[Samuel Pitoiset]

Module: Mesa
Branch: master
Commit: 56d53ed1d69e4c365d146cf37ebaf712362e4755
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=56d53ed1d69e4c365d146cf37ebaf712362e4755

Author: Samuel Pitoiset <samuel.pitoiset at gmail.com>
Date:   Wed May 16 17:43:23 2018 +0200

radv: do not emit unnecessary ES output stores

GFX9:
Totals from affected shaders:
SGPRS: 472 -> 464 (-1.69 %)
VGPRS: 576 -> 584 (1.39 %)
Code Size: 45432 -> 44324 (-2.44 %) bytes
Max Waves: 40 -> 40 (0.00 %)

VI:
SGPRS: 720 -> 720 (0.00 %)
VGPRS: 728 -> 728 (0.00 %)
Code Size: 45348 -> 43992 (-2.99 %) bytes
Max Waves: 120 -> 120 (0.00 %)

This affects Rise of Tomb Raider and the three Vulkan demos
that use a geometry shader (geometryshader, deferredshadows
and viewportarray).

Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>

---

 src/amd/vulkan/radv_nir_to_llvm.c | 26 +++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

diff --git a/src/amd/vulkan/radv_nir_to_llvm.c b/src/amd/vulkan/radv_nir_to_llvm.c
index 05ae709685..82b1e3637f 100644
--- a/src/amd/vulkan/radv_nir_to_llvm.c
+++ b/src/amd/vulkan/radv_nir_to_llvm.c
@@ -2582,14 +2582,26 @@ handle_es_outputs_post(struct radv_shader_context *ctx,
 	for (unsigned i = 0; i < AC_LLVM_MAX_OUTPUTS; ++i) {
 		LLVMValueRef dw_addr = NULL;
 		LLVMValueRef *out_ptr = &ctx->abi.outputs[i * 4];
+		unsigned output_usage_mask;
 		int param_index;
 		int length = 4;
 
 		if (!(ctx->output_mask & (1ull << i)))
 			continue;
 
-		if (i == VARYING_SLOT_CLIP_DIST0)
+		if (ctx->stage == MESA_SHADER_VERTEX) {
+			output_usage_mask =
+				ctx->shader_info->info.vs.output_usage_mask[i];
+		} else {
+			assert(ctx->stage == MESA_SHADER_TESS_EVAL);
+			output_usage_mask =
+				ctx->shader_info->info.tes.output_usage_mask[i];
+		}
+
+		if (i == VARYING_SLOT_CLIP_DIST0) {
 			length = ctx->num_output_clips + ctx->num_output_culls;
+			output_usage_mask = (1 << length) - 1;
+		}
 
 		param_index = shader_io_get_unique_index(i);
 
@@ -2598,14 +2610,22 @@ handle_es_outputs_post(struct radv_shader_context *ctx,
 			                       LLVMConstInt(ctx->ac.i32, param_index * 4, false),
 			                       "");
 		}
+
 		for (j = 0; j < length; j++) {
+			if (!(output_usage_mask & (1 << j)))
+				continue;
+
 			LLVMValueRef out_val = LLVMBuildLoad(ctx->ac.builder, out_ptr[j], "");
 			out_val = LLVMBuildBitCast(ctx->ac.builder, out_val, ctx->ac.i32, "");
 
 			if (ctx->ac.chip_class  >= GFX9) {
-				ac_lds_store(&ctx->ac, dw_addr,
+				LLVMValueRef dw_addr_offset =
+					LLVMBuildAdd(ctx->ac.builder, dw_addr,
+						     LLVMConstInt(ctx->ac.i32,
+								  j, false), "");
+
+				ac_lds_store(&ctx->ac, dw_addr_offset,
 					     LLVMBuildLoad(ctx->ac.builder, out_ptr[j], ""));
-				dw_addr = LLVMBuildAdd(ctx->ac.builder, dw_addr, ctx->ac.i32_1, "");
 			} else {
 				ac_build_buffer_store_dword(&ctx->ac,
 				                            ctx->esgs_ring,