Make deferred draw and constant buffer updates reentrant-safe

At some point we will call Submit within draws or constant buffer updates, to avoid any infinite recursion mark draw/cbuf pending as false before performing any operation

app/src/main/cpp/skyline/soc/gm20b/engines/maxwell_3d.cpp

@@ -19,12 +19,13 @@ namespace skyline::soc::gm20b::engine::maxwell3d {
 
     void Maxwell3D::FlushDeferredDraw() {
         if (deferredDraw.pending) {
+            deferredDraw.pending = false;
+
             if (deferredDraw.indexed)
                 context.DrawIndexed(deferredDraw.drawCount, deferredDraw.drawFirst, deferredDraw.instanceCount, deferredDraw.drawBaseVertex);
             else
                 context.Draw(deferredDraw.drawCount, deferredDraw.drawFirst, deferredDraw.instanceCount);
 
-            deferredDraw.pending = false;
             deferredDraw.instanceCount = 1;
         }
     }
@@ -55,7 +56,7 @@ namespace skyline::soc::gm20b::engine::maxwell3d {
                 #undef CBUF_UPDATE_CALLBACKS
                 default:
                     // When a method other than constant buffer update is called submit our submit the previously built-up update as a batch
-                    context.ConstantBufferUpdate(std::move(batchConstantBufferUpdate.buffer), batchConstantBufferUpdate.startOffset);
+                    context.ConstantBufferUpdate(batchConstantBufferUpdate.buffer, batchConstantBufferUpdate.Invalidate());
                     batchConstantBufferUpdate.Reset();
                     break; // Continue on here to handle the actual method
             }
@@ -771,12 +772,12 @@ namespace skyline::soc::gm20b::engine::maxwell3d {
     }
 
     void Maxwell3D::FlushEngineState() {
+        FlushDeferredDraw();
+
         if (batchConstantBufferUpdate.Active()) {
-            context.ConstantBufferUpdate(std::move(batchConstantBufferUpdate.buffer), batchConstantBufferUpdate.startOffset);
+            context.ConstantBufferUpdate(batchConstantBufferUpdate.buffer, batchConstantBufferUpdate.Invalidate());
             batchConstantBufferUpdate.Reset();
         }
-
-        FlushDeferredDraw();
     }
 
     __attribute__((always_inline)) void Maxwell3D::CallMethod(u32 method, u32 argument) {

app/src/main/cpp/skyline/soc/gm20b/engines/maxwell_3d.h

@@ -31,9 +31,12 @@ namespace skyline::soc::gm20b::engine::maxwell3d {
                 return startOffset != std::numeric_limits<u32>::max();
             }
 
+            u32 Invalidate() {
+                return std::exchange(startOffset, std::numeric_limits<u32>::max());
+            }
+
             void Reset() {
                 buffer.clear();
-                startOffset = std::numeric_limits<u32>::max();
             }
         } batchConstantBufferUpdate; //!< Holds state for updating constant buffer data in a batch rather than word by word