From b35e69b467f37770242e3ba429183517c778be40 Mon Sep 17 00:00:00 2001
From: Philip Rebohle <philip.rebohle@tu-dortmund.de>
Date: Sat, 1 Mar 2025 11:26:43 +0100
Subject: [PATCH] [d3d11] Skip empty draws

Watch Dogs 2 likes to do this with graphics UAVs bound, which
introduces quite a bit of unnecessary GPU synchronization.
---
 src/d3d11/d3d11_context.cpp | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/d3d11/d3d11_context.cpp b/src/d3d11/d3d11_context.cpp
index f9aacc317..9ba60418d 100644
--- a/src/d3d11/d3d11_context.cpp
+++ b/src/d3d11/d3d11_context.cpp
@@ -1037,6 +1037,9 @@ namespace dxvk {
           UINT            StartVertexLocation) {
     D3D10DeviceLock lock = LockContext();
 
+    if (unlikely(!VertexCount))
+      return;
+
     VkDrawIndirectCommand draw = { };
     draw.vertexCount   = VertexCount;
     draw.instanceCount = 1u;
@@ -1054,6 +1057,9 @@ namespace dxvk {
           INT             BaseVertexLocation) {
     D3D10DeviceLock lock = LockContext();
 
+    if (unlikely(!IndexCount))
+      return;
+
     VkDrawIndexedIndirectCommand draw = { };
     draw.indexCount    = IndexCount;
     draw.instanceCount = 1u;
@@ -1073,6 +1079,9 @@ namespace dxvk {
           UINT            StartInstanceLocation) {
     D3D10DeviceLock lock = LockContext();
 
+    if (unlikely(!VertexCountPerInstance || !InstanceCount))
+      return;
+
     VkDrawIndirectCommand draw = { };
     draw.vertexCount   = VertexCountPerInstance;
     draw.instanceCount = InstanceCount;
@@ -1092,6 +1101,9 @@ namespace dxvk {
           UINT            StartInstanceLocation) {
     D3D10DeviceLock lock = LockContext();
 
+    if (unlikely(!IndexCountPerInstance || !InstanceCount))
+      return;
+
     VkDrawIndexedIndirectCommand draw = { };
     draw.indexCount    = IndexCountPerInstance;
     draw.instanceCount = InstanceCount;
@@ -1186,6 +1198,9 @@ namespace dxvk {
           UINT            ThreadGroupCountZ) {
     D3D10DeviceLock lock = LockContext();
 
+    if (unlikely(!ThreadGroupCountX || !ThreadGroupCountY || !ThreadGroupCountZ))
+      return;
+
     if (unlikely(HasDirtyComputeBindings()))
       ApplyDirtyComputeBindings();