Vulkan-Samples/framework/core/pipeline_layout.cpp

/* Copyright (c) 2019-2025, Arm Limited and Contributors
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed under the Apache License, Version 2.0 the "License";
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "pipeline_layout.h"

#include "descriptor_set_layout.h"
#include "device.h"
#include "pipeline.h"
#include "resource_cache.h"
#include "shader_module.h"

namespace vkb
{
PipelineLayout::PipelineLayout(vkb::core::DeviceC &device, const std::vector<ShaderModule *> &shader_modules) :
    device{device},
    shader_modules{shader_modules}
{
	// Collect and combine all the shader resources from each of the shader modules
	// Collate them all into a map that is indexed by the name of the resource
	for (auto *shader_module : shader_modules)
	{
		for (const auto &shader_resource : shader_module->get_resources())
		{
			std::string key = shader_resource.name;

			// Since 'Input' and 'Output' resources can have the same name, we modify the key string
			if (shader_resource.type == ShaderResourceType::Input || shader_resource.type == ShaderResourceType::Output)
			{
				key = std::to_string(shader_resource.stages) + "_" + key;
			}

			auto it = shader_resources.find(key);

			if (it != shader_resources.end())
			{
				// Append stage flags if resource already exists
				it->second.stages |= shader_resource.stages;
			}
			else
			{
				// Create a new entry in the map
				shader_resources.emplace(key, shader_resource);
			}
		}
	}

	// Sift through the map of name indexed shader resources
	// Separate them into their respective sets
	for (auto &it : shader_resources)
	{
		auto &shader_resource = it.second;

		// Find binding by set index in the map.
		auto it2 = shader_sets.find(shader_resource.set);

		if (it2 != shader_sets.end())
		{
			// Add resource to the found set index
			it2->second.push_back(shader_resource);
		}
		else
		{
			// Create a new set index and with the first resource
			shader_sets.emplace(shader_resource.set, std::vector<ShaderResource>{shader_resource});
		}
	}

	// Create a descriptor set layout for each shader set in the shader modules
	for (auto &shader_set_it : shader_sets)
	{
		descriptor_set_layouts.emplace_back(&device.get_resource_cache().request_descriptor_set_layout(shader_set_it.first, shader_modules, shader_set_it.second));
	}

	// Collect all the descriptor set layout handles, maintaining set order
	std::vector<VkDescriptorSetLayout> descriptor_set_layout_handles;
	for (uint32_t i = 0; i < descriptor_set_layouts.size(); ++i)
	{
		if (descriptor_set_layouts[i])
		{
			descriptor_set_layout_handles.push_back(descriptor_set_layouts[i]->get_handle());
		}
		else
		{
			descriptor_set_layout_handles.push_back(VK_NULL_HANDLE);
		}
	}

	// Collect all the push constant shader resources
	std::vector<VkPushConstantRange> push_constant_ranges;
	for (auto &push_constant_resource : get_resources(ShaderResourceType::PushConstant))
	{
		push_constant_ranges.push_back({push_constant_resource.stages, push_constant_resource.offset, push_constant_resource.size});
	}

	VkPipelineLayoutCreateInfo create_info{VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO};

	create_info.setLayoutCount         = to_u32(descriptor_set_layout_handles.size());
	create_info.pSetLayouts            = descriptor_set_layout_handles.data();
	create_info.pushConstantRangeCount = to_u32(push_constant_ranges.size());
	create_info.pPushConstantRanges    = push_constant_ranges.data();

	// Create the Vulkan pipeline layout handle
	auto result = vkCreatePipelineLayout(device.get_handle(), &create_info, nullptr, &handle);

	if (result != VK_SUCCESS)
	{
		throw VulkanException{result, "Cannot create PipelineLayout"};
	}
}

PipelineLayout::PipelineLayout(PipelineLayout &&other) :
    device{other.device},
    handle{other.handle},
    shader_modules{std::move(other.shader_modules)},
    shader_resources{std::move(other.shader_resources)},
    shader_sets{std::move(other.shader_sets)},
    descriptor_set_layouts{std::move(other.descriptor_set_layouts)}
{
	other.handle = VK_NULL_HANDLE;
}

PipelineLayout::~PipelineLayout()
{
	// Destroy pipeline layout
	if (handle != VK_NULL_HANDLE)
	{
		vkDestroyPipelineLayout(device.get_handle(), handle, nullptr);
	}
}

VkPipelineLayout PipelineLayout::get_handle() const
{
	return handle;
}

const std::vector<ShaderModule *> &PipelineLayout::get_shader_modules() const
{
	return shader_modules;
}

const std::vector<ShaderResource> PipelineLayout::get_resources(const ShaderResourceType &type, VkShaderStageFlagBits stage) const
{
	std::vector<ShaderResource> found_resources;

	for (auto &it : shader_resources)
	{
		auto &shader_resource = it.second;

		if (shader_resource.type == type || type == ShaderResourceType::All)
		{
			if (shader_resource.stages == stage || stage == VK_SHADER_STAGE_ALL)
			{
				found_resources.push_back(shader_resource);
			}
		}
	}

	return found_resources;
}

const std::unordered_map<uint32_t, std::vector<ShaderResource>> &PipelineLayout::get_shader_sets() const
{
	return shader_sets;
}

bool PipelineLayout::has_descriptor_set_layout(const uint32_t set_index) const
{
	return set_index < descriptor_set_layouts.size();
}

DescriptorSetLayout &PipelineLayout::get_descriptor_set_layout(const uint32_t set_index) const
{
	for (auto &descriptor_set_layout : descriptor_set_layouts)
	{
		if (descriptor_set_layout->get_index() == set_index)
		{
			return *descriptor_set_layout;
		}
	}
	throw std::runtime_error("Couldn't find descriptor set layout at set index " + to_string(set_index));
}

VkShaderStageFlags PipelineLayout::get_push_constant_range_stage(uint32_t size, uint32_t offset) const
{
	VkShaderStageFlags stages = 0;

	for (auto &push_constant_resource : get_resources(ShaderResourceType::PushConstant))
	{
		if (offset >= push_constant_resource.offset && offset + size <= push_constant_resource.offset + push_constant_resource.size)
		{
			stages |= push_constant_resource.stages;
		}
	}
	return stages;
}
}        // namespace vkb