renderer_base: Make Rasterizer() return the rasterizer by reference

All calling code assumes that the rasterizer will be in a valid state,
which is a totally fine assumption. The only way the rasterizer wouldn't
be is if initialization is done incorrectly or fails, which is checked
against in System::Init().

src/core/core.cpp

@@ -187,7 +187,7 @@ System::ResultStatus System::Init(EmuWindow& emu_window) {
         return ResultStatus::ErrorVideoCore;
     }
 
-    gpu_core = std::make_unique<Tegra::GPU>(*renderer->Rasterizer());
+    gpu_core = std::make_unique<Tegra::GPU>(renderer->Rasterizer());
 
     // Create threads for CPU cores 1-3, and build thread_to_cpu map
     // CPU core 0 is run on the main thread

src/core/hle/service/nvdrv/devices/nvhost_as_gpu.cpp

@@ -156,7 +156,7 @@ u32 nvhost_as_gpu::UnmapBuffer(const std::vector<u8>& input, std::vector<u8>& ou
     auto& system_instance = Core::System::GetInstance();
 
     // Remove this memory region from the rasterizer cache.
-    system_instance.Renderer().Rasterizer()->FlushAndInvalidateRegion(params.offset,
+    system_instance.Renderer().Rasterizer().FlushAndInvalidateRegion(params.offset,
                                                                      itr->second.size);
 
     auto& gpu = system_instance.GPU();

src/core/memory.cpp

@@ -355,16 +355,16 @@ void RasterizerFlushVirtualRegion(VAddr start, u64 size, FlushMode mode) {
         const u64 overlap_size = overlap_end - overlap_start;
 
         for (const auto& gpu_address : gpu_addresses) {
-            auto* rasterizer = system_instance.Renderer().Rasterizer();
+            auto& rasterizer = system_instance.Renderer().Rasterizer();
             switch (mode) {
             case FlushMode::Flush:
-                rasterizer->FlushRegion(gpu_address, overlap_size);
+                rasterizer.FlushRegion(gpu_address, overlap_size);
                 break;
             case FlushMode::Invalidate:
-                rasterizer->InvalidateRegion(gpu_address, overlap_size);
+                rasterizer.InvalidateRegion(gpu_address, overlap_size);
                 break;
             case FlushMode::FlushAndInvalidate:
-                rasterizer->FlushAndInvalidateRegion(gpu_address, overlap_size);
+                rasterizer.FlushAndInvalidateRegion(gpu_address, overlap_size);
                 break;
             }
         }

src/video_core/renderer_base.h

@@ -46,8 +46,12 @@ public:
         return m_current_frame;
     }
 
-    RasterizerInterface* Rasterizer() const {
+    RasterizerInterface& Rasterizer() {
-        return rasterizer.get();
+        return *rasterizer;
+    }
+
+    const RasterizerInterface& Rasterizer() const {
+        return *rasterizer;
     }
 
     void RefreshRasterizerSetting();

src/video_core/renderer_opengl/renderer_opengl.cpp

@@ -160,7 +160,7 @@ void RendererOpenGL::LoadFBToScreenInfo(const Tegra::FramebufferConfig& framebuf
     // only allows rows to have a memory alignement of 4.
     ASSERT(framebuffer.stride % 4 == 0);
 
-    if (!Rasterizer()->AccelerateDisplay(framebuffer, framebuffer_addr, framebuffer.stride,
+    if (!rasterizer->AccelerateDisplay(framebuffer, framebuffer_addr, framebuffer.stride,
                                        screen_info)) {
         // Reset the screen info's display texture to its own permanent texture
         screen_info.display_texture = screen_info.texture.resource.handle;