[Mesa-dev] [PATCH v2 08/14] radeonsi: Store inputs to memory when not using a TCS.

[Bas Nieuwenhuizen]

We need to copy the VS outputs to memory. I decided to do this
using a shader key, as the value depends on other shaders.

I also switch the fixed function TCS over to monolithic, as
otherwisze many of the user SGPR's need to be passed to the
epilog, which increases register pressure, or complexity to
avoid that. The main body of the fixed function TCS is not
that interesting to precompile anyway, since we do it on
demand and it is very small.

v2: Use u_bit_scan64.

Signed-off-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>
---
 src/gallium/drivers/radeonsi/si_shader.c        | 45 +++++++++++++++++++++++++
 src/gallium/drivers/radeonsi/si_shader.h        |  1 +
 src/gallium/drivers/radeonsi/si_state_shaders.c |  3 ++
 3 files changed, 49 insertions(+)

diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
index 46070ab..d44dc91 100644
--- a/src/gallium/drivers/radeonsi/si_shader.c
+++ b/src/gallium/drivers/radeonsi/si_shader.c
@@ -2438,6 +2438,48 @@ handle_semantic:
 	}
 }
 
+static void si_copy_tcs_inputs(struct lp_build_tgsi_context *bld_base)
+{
+	struct si_shader_context *ctx = si_shader_context(bld_base);
+	struct gallivm_state *gallivm = bld_base->base.gallivm;
+	LLVMValueRef invocation_id, rw_buffers, buffer, buffer_offset;
+	LLVMValueRef lds_vertex_stride, lds_vertex_offset, lds_base;
+	uint64_t inputs;
+
+	invocation_id = unpack_param(ctx, SI_PARAM_REL_IDS, 8, 5);
+
+	rw_buffers = LLVMGetParam(ctx->radeon_bld.main_fn, SI_PARAM_RW_BUFFERS);
+	buffer = build_indexed_load_const(ctx, rw_buffers,
+	                lp_build_const_int32(gallivm, SI_HS_RING_TESS_OFFCHIP));
+
+	buffer_offset = LLVMGetParam(ctx->radeon_bld.main_fn, ctx->param_oc_lds);
+
+	lds_vertex_stride = unpack_param(ctx, SI_PARAM_TCS_IN_LAYOUT, 13, 8);
+	lds_vertex_offset = LLVMBuildMul(gallivm->builder, invocation_id,
+	                                 lds_vertex_stride, "");
+	lds_base = get_tcs_in_current_patch_offset(ctx);
+	lds_base = LLVMBuildAdd(gallivm->builder, lds_base, lds_vertex_offset, "");
+
+	inputs = ctx->shader->key.tcs.epilog.inputs_to_copy;
+	while (inputs) {
+		unsigned i = u_bit_scan64(&inputs);
+
+		LLVMValueRef lds_ptr = LLVMBuildAdd(gallivm->builder, lds_base,
+		                            lp_build_const_int32(gallivm, 4 * i),
+		                             "");
+
+		LLVMValueRef buffer_addr = get_tcs_tes_buffer_address(ctx,
+		                              invocation_id,
+		                              lp_build_const_int32(gallivm, i));
+
+		LLVMValueRef value = lds_load(bld_base, TGSI_TYPE_SIGNED, ~0,
+		                              lds_ptr);
+
+		build_tbuffer_store_dwords(ctx, buffer, value, 4, buffer_addr,
+		                           buffer_offset, 0);
+	}
+}
+
 static void si_write_tess_factors(struct lp_build_tgsi_context *bld_base,
 				  LLVMValueRef rel_patch_id,
 				  LLVMValueRef invocation_id,
@@ -2579,6 +2621,7 @@ static void si_llvm_emit_tcs_epilogue(struct lp_build_tgsi_context *bld_base)
 		return;
 	}
 
+	si_copy_tcs_inputs(bld_base);
 	si_write_tess_factors(bld_base, rel_patch_id, invocation_id, tf_lds_offset);
 }
 
@@ -7389,6 +7432,8 @@ int si_shader_create(struct si_screen *sscreen, LLVMTargetMachineRef tm,
 	      shader->key.vs.as_ls != mainp->key.vs.as_ls)) ||
 	    (shader->selector->type == PIPE_SHADER_TESS_EVAL &&
 	     shader->key.tes.as_es != mainp->key.tes.as_es) ||
+	    (shader->selector->type == PIPE_SHADER_TESS_CTRL &&
+	     shader->key.tcs.epilog.inputs_to_copy) ||
 	    shader->selector->type == PIPE_SHADER_COMPUTE) {
 		/* Monolithic shader (compiled as a whole, has many variants,
 		 * may take a long time to compile).
diff --git a/src/gallium/drivers/radeonsi/si_shader.h b/src/gallium/drivers/radeonsi/si_shader.h
index 26be25e..67b457b 100644
--- a/src/gallium/drivers/radeonsi/si_shader.h
+++ b/src/gallium/drivers/radeonsi/si_shader.h
@@ -304,6 +304,7 @@ struct si_vs_epilog_bits {
 /* Common TCS bits between the shader key and the epilog key. */
 struct si_tcs_epilog_bits {
 	unsigned	prim_mode:3;
+	uint64_t	inputs_to_copy;
 };
 
 /* Common PS bits between the shader key and the prolog key. */
diff --git a/src/gallium/drivers/radeonsi/si_state_shaders.c b/src/gallium/drivers/radeonsi/si_state_shaders.c
index 99ca33e..26f9960 100644
--- a/src/gallium/drivers/radeonsi/si_state_shaders.c
+++ b/src/gallium/drivers/radeonsi/si_state_shaders.c
@@ -846,6 +846,9 @@ static inline void si_shader_selector_key(struct pipe_context *ctx,
 	case PIPE_SHADER_TESS_CTRL:
 		key->tcs.epilog.prim_mode =
 			sctx->tes_shader.cso->info.properties[TGSI_PROPERTY_TES_PRIM_MODE];
+
+		if (sel == sctx->fixed_func_tcs_shader.cso)
+			key->tcs.epilog.inputs_to_copy = sctx->vs_shader.cso->outputs_written;
 		break;
 	case PIPE_SHADER_TESS_EVAL:
 		if (sctx->gs_shader.cso)
-- 
2.8.2