Mesa (master): ac/nir: don't write tcs outputs to LDS that aren' t read back.

[Dave Airlie]

Module: Mesa
Branch: master
Commit: 043d14db30a849013005409c32ced8b756fec540
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=043d14db30a849013005409c32ced8b756fec540

Author: Dave Airlie <airlied at redhat.com>
Date:   Tue Nov 14 15:11:39 2017 +1000

ac/nir: don't write tcs outputs to LDS that aren't read back.

If the TCS doesn't read back the outputs, no need to store them
to LDS in the first place. (except for tess factors).

This seems to give about 50fps (3290->3330) with tessellation demo.

I haven't tested if it impacts DoW3 at all.

Reviewed-by: Marek Olšák <marek.olsak at amd.com>
Signed-off-by: Dave Airlie <airlied at redhat.com>

---

 src/amd/common/ac_nir_to_llvm.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/amd/common/ac_nir_to_llvm.c b/src/amd/common/ac_nir_to_llvm.c
index 1ecdeca063..b58bae90c5 100644
--- a/src/amd/common/ac_nir_to_llvm.c
+++ b/src/amd/common/ac_nir_to_llvm.c
@@ -149,6 +149,9 @@ struct nir_to_llvm_context {
 	unsigned tes_primitive_mode;
 	uint64_t tess_outputs_written;
 	uint64_t tess_patch_outputs_written;
+
+	uint32_t tcs_patch_outputs_read;
+	uint64_t tcs_outputs_read;
 };
 
 static inline struct nir_to_llvm_context *
@@ -2789,7 +2792,15 @@ store_tcs_output(struct nir_to_llvm_context *ctx,
 	const unsigned comp = instr->variables[0]->var->data.location_frac;
 	const bool per_vertex = nir_is_per_vertex_io(instr->variables[0]->var, ctx->stage);
 	const bool is_compact = instr->variables[0]->var->data.compact;
+	bool store_lds = true;
 
+	if (instr->variables[0]->var->data.patch) {
+		if (!(ctx->tcs_patch_outputs_read & (1U << instr->variables[0]->var->data.location)))
+			store_lds = false;
+	} else {
+		if (!(ctx->tcs_outputs_read & (1ULL << instr->variables[0]->var->data.location)))
+			store_lds = false;
+	}
 	get_deref_offset(ctx->nir, instr->variables[0],
 			 false, NULL, per_vertex ? &vertex_index : NULL,
 			 &const_index, &indir_index);
@@ -2826,7 +2837,8 @@ store_tcs_output(struct nir_to_llvm_context *ctx,
 			continue;
 		LLVMValueRef value = llvm_extract_elem(&ctx->ac, src, chan - comp);
 
-		ac_lds_store(&ctx->ac, dw_addr, value);
+		if (store_lds || is_tess_factor)
+			ac_lds_store(&ctx->ac, dw_addr, value);
 
 		if (!is_tess_factor && writemask != 0xF)
 			ac_build_buffer_store_dword(&ctx->ac, ctx->hs_ring_tess_offchip, value, 1,
@@ -6550,6 +6562,9 @@ LLVMModuleRef ac_translate_nir_to_llvm(LLVMTargetMachineRef tm,
 			ctx.gs_next_vertex = ac_build_alloca(&ctx.ac, ctx.ac.i32, "gs_next_vertex");
 
 			ctx.gs_max_out_vertices = shaders[i]->info.gs.vertices_out;
+		} else if (shaders[i]->info.stage == MESA_SHADER_TESS_CTRL) {
+			ctx.tcs_outputs_read = shaders[i]->info.outputs_read;
+			ctx.tcs_patch_outputs_read = shaders[i]->info.patch_outputs_read;
 		} else if (shaders[i]->info.stage == MESA_SHADER_TESS_EVAL) {
 			ctx.tes_primitive_mode = shaders[i]->info.tess.primitive_mode;
 		} else if (shaders[i]->info.stage == MESA_SHADER_VERTEX) {