radv/ac: add initial pre-pass for shader info gathering

There is some radv specific info we need to gather from shaders
before we get into converting nir->llvm, so we can make
better decisions especially around user sgpr allocation.

This is just an initial placeholder to gather if sample positions
are required in the frag shader.

Reviewed-by: Bas Nieuwenhuizen <[email protected]>
Signed-off-by: Dave Airlie <[email protected]>

4 files changed, 113 insertions, 8 deletions

diff --git a/src/amd/common/ac_nir_to_llvm.c b/src/amd/common/ac_nir_to_llvm.c
index 9bcd5f6db46..dbb3b67b511 100644
--- a/src/amd/common/ac_nir_to_llvm.c
+++ b/src/amd/common/ac_nir_to_llvm.c
@@ -30,7 +30,7 @@
 #include "../vulkan/radv_descriptor_set.h"
 #include "util/bitscan.h"
 #include <llvm-c/Transforms/Scalar.h>
-
+#include "ac_shader_info.h"
 enum radeon_llvm_calling_convention {
 	RADEON_LLVM_AMDGPU_VS = 87,
 	RADEON_LLVM_AMDGPU_GS = 88,
@@ -680,7 +680,8 @@ static void create_function(struct nir_to_llvm_context *ctx)
 		arg_types[arg_idx++] = ctx->i32; // GS instance id
 		break;
 	case MESA_SHADER_FRAGMENT:
-		arg_types[arg_idx++] = ctx->i32; /* sample position offset */
+		if (ctx->shader_info->info.ps.needs_sample_positions)
+			arg_types[arg_idx++] = ctx->i32; /* sample position offset */
 		user_sgpr_count = arg_idx;
 		arg_types[arg_idx++] = ctx->i32; /* prim mask */
 		sgpr_count = arg_idx;
@@ -845,9 +846,11 @@ static void create_function(struct nir_to_llvm_context *ctx)
 		ctx->gs_invocation_id = LLVMGetParam(ctx->main_function, arg_idx++);
 		break;
 	case MESA_SHADER_FRAGMENT:
-		set_userdata_location_shader(ctx, AC_UD_PS_SAMPLE_POS_OFFSET, user_sgpr_idx, 1);
-		user_sgpr_idx += 1;
-		ctx->sample_pos_offset = LLVMGetParam(ctx->main_function, arg_idx++);
+		if (ctx->shader_info->info.ps.needs_sample_positions) {
+			set_userdata_location_shader(ctx, AC_UD_PS_SAMPLE_POS_OFFSET, user_sgpr_idx, 1);
+			user_sgpr_idx += 1;
+			ctx->sample_pos_offset = LLVMGetParam(ctx->main_function, arg_idx++);
+		}
 		ctx->prim_mask = LLVMGetParam(ctx->main_function, arg_idx++);
 		ctx->persp_sample = LLVMGetParam(ctx->main_function, arg_idx++);
 		ctx->persp_center = LLVMGetParam(ctx->main_function, arg_idx++);
@@ -3528,7 +3531,6 @@ static LLVMValueRef load_sample_position(struct nir_to_llvm_context *ctx,
 	sample_id = LLVMBuildAdd(ctx->builder, sample_id, ctx->sample_pos_offset, "");
 	result = ac_build_indexed_load(&ctx->ac, ptr, sample_id, false);
 
-	ctx->shader_info->fs.uses_sample_positions = true;
 	return result;
 }
 
@@ -5703,6 +5705,8 @@ LLVMModuleRef ac_translate_nir_to_llvm(LLVMTargetMachineRef tm,
 
 	memset(shader_info, 0, sizeof(*shader_info));
 
+	ac_nir_shader_info_pass(nir, options, &shader_info->info);
+		
 	LLVMSetTarget(ctx.module, options->supports_spill ? "amdgcn-mesa-mesa3d" : "amdgcn--");
 
 	LLVMTargetDataRef data_layout = LLVMCreateTargetDataLayout(tm);
diff --git a/src/amd/common/ac_nir_to_llvm.h b/src/amd/common/ac_nir_to_llvm.h
index 3d0b456f9f5..7a4065ac5fa 100644
--- a/src/amd/common/ac_nir_to_llvm.h
+++ b/src/amd/common/ac_nir_to_llvm.h
@@ -29,7 +29,7 @@
 #include "llvm-c/TargetMachine.h"
 #include "amd_family.h"
 #include "../vulkan/radv_descriptor_set.h"
-
+#include "ac_shader_info.h"
 #include "shader_enums.h"
 struct ac_shader_binary;
 struct ac_shader_config;
@@ -138,6 +138,7 @@ struct ac_es_output_info {
 
 struct ac_shader_variant_info {
 	struct ac_userdata_locations user_sgprs_locs;
+	struct ac_shader_info info;
 	unsigned num_user_sgprs;
 	unsigned num_input_sgprs;
 	unsigned num_input_vgprs;
@@ -166,7 +167,6 @@ struct ac_shader_variant_info {
 			bool force_persample;
 			bool prim_id_input;
 			bool layer_input;
-			bool uses_sample_positions;
 		} fs;
 		struct {
 			unsigned block_size[3];
diff --git a/src/amd/common/ac_shader_info.c b/src/amd/common/ac_shader_info.c
new file mode 100644
index 00000000000..85252fea146
--- /dev/null
+++ b/src/amd/common/ac_shader_info.c
@@ -0,0 +1,61 @@
+/*
+ * Copyright © 2017 Red Hat
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+#include "nir.h"
+#include "ac_shader_info.h"
+#include "ac_nir_to_llvm.h"
+static void
+gather_intrinsic_info(nir_intrinsic_instr *instr, struct ac_shader_info *info)
+{
+	switch (instr->intrinsic) {
+	case nir_intrinsic_interp_var_at_sample:
+		info->ps.needs_sample_positions = true;
+		break;
+	default:
+		break;
+	}
+}
+
+static void
+gather_info_block(nir_block *block, struct ac_shader_info *info)
+{
+	nir_foreach_instr(instr, block) {
+		switch (instr->type) {
+		case nir_instr_type_intrinsic:
+			gather_intrinsic_info(nir_instr_as_intrinsic(instr), info);
+			break;
+		default:
+			break;
+		}
+	}
+}
+
+void
+ac_nir_shader_info_pass(struct nir_shader *nir,
+			const struct ac_nir_compiler_options *options,
+			struct ac_shader_info *info)
+{
+	struct nir_function *func = (struct nir_function *)exec_list_get_head(&nir->functions);
+	nir_foreach_block(block, func->impl) {
+		gather_info_block(block, info);
+	}
+}
diff --git a/src/amd/common/ac_shader_info.h b/src/amd/common/ac_shader_info.h
new file mode 100644
index 00000000000..5576c3b4bac
--- /dev/null
+++ b/src/amd/common/ac_shader_info.h
@@ -0,0 +1,40 @@
+/*
+ * Copyright © 2017 Red Hat
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+#ifndef AC_SHADER_INFO_H
+#define AC_SHADER_INFO_H
+struct nir_shader;
+struct ac_nir_compiler_options;
+
+/* a NIR pass to gather all the info needed to optimise the alloction patterns for the RADV user sgprs */
+
+struct ac_shader_info {
+	struct {
+		bool needs_sample_positions;
+	} ps;
+};
+
+void
+ac_nir_shader_info_pass(struct nir_shader *nir,
+			const struct ac_nir_compiler_options *options,
+			struct ac_shader_info *info);
+#endif