From 2249b873ff78454160096b46f39c277211580fdc Mon Sep 17 00:00:00 2001
From: Connor McLaughlin <stenzek@gmail.com>
Date: Sun, 8 Mar 2020 12:51:14 +1000
Subject: [PATCH] D3D11/StreamBuffer: Check feature support for
 MAP_NO_OVERWRITE before using

---
 src/common/d3d11/stream_buffer.cpp | 29 +++++++++++++++++++++++++++--
 src/common/d3d11/stream_buffer.h   |  1 +
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/src/common/d3d11/stream_buffer.cpp b/src/common/d3d11/stream_buffer.cpp
index c10acb276..38fbc4221 100644
--- a/src/common/d3d11/stream_buffer.cpp
+++ b/src/common/d3d11/stream_buffer.cpp
@@ -24,7 +24,7 @@ bool StreamBuffer::Create(ID3D11Device* device, D3D11_BIND_FLAG bind_flags, u32
 {
   CD3D11_BUFFER_DESC desc(size, bind_flags, D3D11_USAGE_DYNAMIC, D3D11_CPU_ACCESS_WRITE, 0, 0);
   ComPtr<ID3D11Buffer> buffer;
-  const HRESULT hr = device->CreateBuffer(&desc, nullptr, &buffer);
+  HRESULT hr = device->CreateBuffer(&desc, nullptr, &buffer);
   if (FAILED(hr))
   {
     Log_ErrorPrintf("Creating buffer failed: 0x%08X", hr);
@@ -34,6 +34,31 @@ bool StreamBuffer::Create(ID3D11Device* device, D3D11_BIND_FLAG bind_flags, u32
   m_buffer = std::move(buffer);
   m_size = size;
   m_position = 0;
+
+  D3D11_FEATURE_DATA_D3D11_OPTIONS options = {};
+  hr = device->CheckFeatureSupport(D3D11_FEATURE_D3D11_OPTIONS, &options, sizeof(options));
+  if (SUCCEEDED(hr))
+  {
+    if (bind_flags & D3D11_BIND_CONSTANT_BUFFER)
+      m_use_map_no_overwrite = options.MapNoOverwriteOnDynamicConstantBuffer;
+    else if (bind_flags & D3D11_BIND_SHADER_RESOURCE)
+      m_use_map_no_overwrite = options.MapNoOverwriteOnDynamicBufferSRV;
+    else
+      m_use_map_no_overwrite = true;
+
+    if (!m_use_map_no_overwrite)
+    {
+      Log_WarningPrintf("Unable to use MAP_NO_OVERWRITE on buffer with bind flag %u, this may affect performance. "
+                        "Update your driver/operating system.",
+                        static_cast<unsigned>(bind_flags));
+    }
+  }
+  else
+  {
+    Log_WarningPrintf("ID3D11Device::CheckFeatureSupport() failed: 0x%08X", hr);
+    m_use_map_no_overwrite = false;
+  }
+
   return true;
 }
 
@@ -55,7 +80,7 @@ void StreamBuffer::Release()
 StreamBuffer::MappingResult StreamBuffer::Map(ID3D11DeviceContext* context, u32 alignment, u32 min_size)
 {
   m_position = Common::AlignUp(m_position, alignment);
-  if ((m_position + min_size) >= m_size)
+  if ((m_position + min_size) >= m_size || !m_use_map_no_overwrite)
   {
     // wrap around
     m_position = 0;
diff --git a/src/common/d3d11/stream_buffer.h b/src/common/d3d11/stream_buffer.h
index cdc62931f..2e46f1862 100644
--- a/src/common/d3d11/stream_buffer.h
+++ b/src/common/d3d11/stream_buffer.h
@@ -39,5 +39,6 @@ private:
   ComPtr<ID3D11Buffer> m_buffer;
   u32 m_size;
   u32 m_position;
+  bool m_use_map_no_overwrite = false;
 };
 } // namespace GL
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