[Mesa-dev] [PATCH] radv: improve gathering of load_push_constants with dynamic bindings

[Samuel Pitoiset]

For example, if a pipeline has two stages VS and FS. And if only
the fragment stage needs dynamic bindings, we shouldn't allocate
an extra user SGPR for the vertex stage. Of course, if the vertex
stage loads constants, it needs an user SGPR.

This should reduce the number of SET_SH_REG packets that are emitted.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
---
 src/amd/vulkan/radv_descriptor_set.c | 3 +++
 src/amd/vulkan/radv_descriptor_set.h | 1 +
 src/amd/vulkan/radv_shader_info.c    | 4 +++-
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/amd/vulkan/radv_descriptor_set.c b/src/amd/vulkan/radv_descriptor_set.c
index 526bb77a553..30f982252bb 100644
--- a/src/amd/vulkan/radv_descriptor_set.c
+++ b/src/amd/vulkan/radv_descriptor_set.c
@@ -345,6 +345,7 @@ VkResult radv_CreatePipelineLayout(
 	layout->num_sets = pCreateInfo->setLayoutCount;
 
 	unsigned dynamic_offset_count = 0;
+	uint16_t dynamic_shader_stages = 0;
 
 
 	_mesa_sha1_init(&ctx);
@@ -356,6 +357,7 @@ VkResult radv_CreatePipelineLayout(
 		layout->set[set].dynamic_offset_start = dynamic_offset_count;
 		for (uint32_t b = 0; b < set_layout->binding_count; b++) {
 			dynamic_offset_count += set_layout->binding[b].array_size * set_layout->binding[b].dynamic_offset_count;
+			dynamic_shader_stages |= set_layout->dynamic_shader_stages;
 			if (set_layout->binding[b].immutable_samplers_offset)
 				_mesa_sha1_update(&ctx, radv_immutable_samplers(set_layout, set_layout->binding + b),
 				                  set_layout->binding[b].array_size * 4 * sizeof(uint32_t));
@@ -365,6 +367,7 @@ VkResult radv_CreatePipelineLayout(
 	}
 
 	layout->dynamic_offset_count = dynamic_offset_count;
+	layout->dynamic_shader_stages = dynamic_shader_stages;
 	layout->push_constant_size = 0;
 
 	for (unsigned i = 0; i < pCreateInfo->pushConstantRangeCount; ++i) {
diff --git a/src/amd/vulkan/radv_descriptor_set.h b/src/amd/vulkan/radv_descriptor_set.h
index d8431241fd9..7b13c6fb621 100644
--- a/src/amd/vulkan/radv_descriptor_set.h
+++ b/src/amd/vulkan/radv_descriptor_set.h
@@ -85,6 +85,7 @@ struct radv_pipeline_layout {
    uint32_t num_sets;
    uint32_t push_constant_size;
    uint32_t dynamic_offset_count;
+   uint16_t dynamic_shader_stages;
 
    unsigned char sha1[20];
 };
diff --git a/src/amd/vulkan/radv_shader_info.c b/src/amd/vulkan/radv_shader_info.c
index c2e005e63dd..7e5a3789af2 100644
--- a/src/amd/vulkan/radv_shader_info.c
+++ b/src/amd/vulkan/radv_shader_info.c
@@ -512,8 +512,10 @@ radv_nir_shader_info_pass(const struct nir_shader *nir,
 	struct nir_function *func =
 		(struct nir_function *)exec_list_get_head_const(&nir->functions);
 
-	if (options->layout && options->layout->dynamic_offset_count)
+	if (options->layout && options->layout->dynamic_offset_count &&
+	    (options->layout->dynamic_shader_stages & mesa_to_vk_shader_stage(nir->info.stage))) {
 		info->loads_push_constants = true;
+	}
 
 	nir_foreach_variable(variable, &nir->inputs)
 		gather_info_input_decl(nir, variable, info);
-- 
2.20.1