From 9a6c378f3d7219961706f73dc85c8fcfa9a23e0c Mon Sep 17 00:00:00 2001
From: Philip Rebohle <philip.rebohle@tu-dortmund.de>
Date: Wed, 10 Aug 2022 17:58:04 +0200
Subject: [PATCH] [dxvk] Only use one descriptor set for compute shaders

Simplifies things a bit and avoids redundant sets in the pipeline layout.
---
 src/dxvk/dxvk_pipelayout.cpp | 23 +++++++++++++++++------
 src/dxvk/dxvk_pipelayout.h   |  9 +++++----
 2 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/src/dxvk/dxvk_pipelayout.cpp b/src/dxvk/dxvk_pipelayout.cpp
index ff3b097e..67c01ca8 100644
--- a/src/dxvk/dxvk_pipelayout.cpp
+++ b/src/dxvk/dxvk_pipelayout.cpp
@@ -9,7 +9,10 @@
 namespace dxvk {
   
   uint32_t DxvkBindingInfo::computeSetIndex() const {
-    if (stages & (VK_SHADER_STAGE_FRAGMENT_BIT | VK_SHADER_STAGE_COMPUTE_BIT)) {
+    if (stages & VK_SHADER_STAGE_COMPUTE_BIT) {
+      // Use one single set for compute shaders
+      return DxvkDescriptorSets::CsAll;
+    } else if (stages & VK_SHADER_STAGE_FRAGMENT_BIT) {
       // For fragment shaders, create a separate set for UBOs
       if (descriptorType == VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER
        || descriptorType == VK_DESCRIPTOR_TYPE_STORAGE_BUFFER)
@@ -215,12 +218,15 @@ namespace dxvk {
   uint32_t DxvkBindingLayout::getSetMask() const {
     uint32_t mask = 0;
 
-    if (m_stages & (VK_SHADER_STAGE_COMPUTE_BIT | VK_SHADER_STAGE_FRAGMENT_BIT)) {
+    if (m_stages & VK_SHADER_STAGE_COMPUTE_BIT)
+      mask |= (1u << DxvkDescriptorSets::CsAll);
+
+    if (m_stages & VK_SHADER_STAGE_FRAGMENT_BIT) {
       mask |= (1u << DxvkDescriptorSets::FsViews)
            |  (1u << DxvkDescriptorSets::FsBuffers);
     }
 
-    if (m_stages & (VK_SHADER_STAGE_COMPUTE_BIT | VK_SHADER_STAGE_VERTEX_BIT))
+    if (m_stages & VK_SHADER_STAGE_VERTEX_BIT)
       mask |= (1u << DxvkDescriptorSets::VsAll);
 
     return mask;
@@ -292,7 +298,12 @@ namespace dxvk {
 
     std::array<VkDescriptorSetLayout, DxvkDescriptorSets::SetCount> setLayouts = { };
 
-    for (uint32_t i = 0; i < DxvkDescriptorSets::SetCount; i++) {
+    // Use minimum number of sets for the given pipeline layout type
+    uint32_t setCount = m_layout.getStages() == VK_SHADER_STAGE_COMPUTE_BIT
+      ? DxvkDescriptorSets::CsSetCount
+      : DxvkDescriptorSets::SetCount;
+
+    for (uint32_t i = 0; i < setCount; i++) {
       m_bindingObjects[i] = setObjects[i];
 
       // Sets can be null for partial layouts
@@ -322,7 +333,7 @@ namespace dxvk {
     VkPushConstantRange pushConst = m_layout.getPushConstantRange();
 
     VkPipelineLayoutCreateInfo pipelineLayoutInfo = { VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO };
-    pipelineLayoutInfo.setLayoutCount = setLayouts.size();
+    pipelineLayoutInfo.setLayoutCount = setCount;
     pipelineLayoutInfo.pSetLayouts = setLayouts.data();
 
     if (pushConst.stageFlags && pushConst.size) {
@@ -331,7 +342,7 @@ namespace dxvk {
     }
 
     // If the full set is defined, create a layout without INDEPENDENT_SET_BITS
-    if (m_layout.getSetMask() == (1u << DxvkDescriptorSets::SetCount) - 1) {
+    if (m_layout.getSetMask() == (1u << setCount) - 1) {
       if (vk->vkCreatePipelineLayout(vk->device(), &pipelineLayoutInfo, nullptr, &m_completeLayout))
         throw DxvkError("DxvkBindingLayoutObjects: Failed to create pipeline layout");
     }
diff --git a/src/dxvk/dxvk_pipelayout.h b/src/dxvk/dxvk_pipelayout.h
index f559e6c0..b7b16c35 100644
--- a/src/dxvk/dxvk_pipelayout.h
+++ b/src/dxvk/dxvk_pipelayout.h
@@ -19,6 +19,9 @@ namespace dxvk {
     static constexpr uint32_t FsBuffers   = 1;
     static constexpr uint32_t VsAll       = 2;
     static constexpr uint32_t SetCount    = 3;
+
+    static constexpr uint32_t CsAll       = 0;
+    static constexpr uint32_t CsSetCount  = 1;
   };
 
   /**
@@ -535,10 +538,8 @@ namespace dxvk {
 
     uint32_t getDirtyComputeSets() const {
       uint32_t result = 0;
-      if (m_dirtyBuffers & VK_SHADER_STAGE_COMPUTE_BIT)
-        result |= (1u << DxvkDescriptorSets::FsBuffers);
-      if (m_dirtyViews & VK_SHADER_STAGE_COMPUTE_BIT)
-        result |= (1u << DxvkDescriptorSets::FsViews) | (1u << DxvkDescriptorSets::FsBuffers);
+      if ((m_dirtyBuffers | m_dirtyViews) & VK_SHADER_STAGE_COMPUTE_BIT)
+        result |= (1u << DxvkDescriptorSets::CsAll);
       return result;
     }