NVAPI improvements (#1512)

* First pass at incorporating nvapi into test harness.

* D3d12 Atomic Float Add via NVAPI working

* Dx12 atomic float appears to work.

* Atomic float add on Dx12.

* Added atomic64 feature addition to vk.
Fix correct output for atomic-float-byte-address.slang

* Disable atomic float failing tests.

* Upgraded VK headers.

* Detect atomic float availability on VK.

* Try to get test working for in64 atomic.

* Made HLSL prelude controlled via the render-test requirements.

* Added -enable-nvapi to premake.

* Fix D3D12Renderer when NVAPI is not available.

* Small improvements to VKRenderer.

* Improve atomic documentation in target-compatibility.md.

* Fixed NVAPI working on D3D12.

* Test for specific NVAPI features.

* Remove requiredFeatures from Renderer::Desc as was ignored. Tried to document more around nvapiExtnSlot.

* Readded requiredFeatures to Renderer::Desc

* Improve comments in the tests.

1 files changed, 5 insertions, 2 deletions

diff --git a/tools/gfx/open-gl/render-gl.cpp b/tools/gfx/open-gl/render-gl.cpp
index 5f16f07bc..caf8794c0 100644
--- a/tools/gfx/open-gl/render-gl.cpp
+++ b/tools/gfx/open-gl/render-gl.cpp
@@ -717,9 +717,12 @@ SlangResult GLRenderer::initialize(const Desc& desc, void* inWindowHandle)
         }
     }
 
-    if (m_desc.requiredFeatures.indexOf("nvapi") >= 0 && SLANG_SUCCEEDED(NVAPIUtil::initialize()))
+    if (m_desc.nvapiExtnSlot >= 0)
     {
-        m_features.add("nvapi");
+        if (SLANG_FAILED(NVAPIUtil::initialize()))
+        {
+            return SLANG_E_NOT_AVAILABLE;
+        }
     }
 
     auto extensions = glGetString(GL_EXTENSIONS);