renderer_opengl: Add assembly program code paths

Add code required to use OpenGL assembly programs based on
NV_gpu_program5. Decompilation for ARB programs is intended to be added
in a follow up commit. This does **not** include ARB decompilation and
it's not in an usable state.

The intention behind assembly programs is to reduce shader stutter
significantly on drivers supporting NV_gpu_program5 (and other required
extensions). Currently only Nvidia's proprietary driver supports these
extensions.

Add a UI option hidden for now to avoid people enabling this option
accidentally.

This code path has some limitations that OpenGL compatibility doesn't
have:
- NV_shader_storage_buffer_object is limited to 16 entries for a single
OpenGL context state (I don't know if this is an intended limitation, an
specification issue or I am missing something). Currently causes issues
on The Legend of Zelda: Link's Awakening.
- NV_parameter_buffer_object can't bind buffers using an offset
different to zero. The used workaround is to copy to a temporary buffer
(this doesn't happen often so it's not an issue).

On the other hand, it has the following advantages:
- Shaders build a lot faster.
- We have control over how floating point rounding is done over
individual instructions (SPIR-V on Vulkan can't do this).
- Operations on shared memory can be unsigned and signed.
- Transform feedbacks are dynamic state (not yet implemented).
- Parameter buffers (uniform buffers) are per stage, matching NVN and
hardware's behavior.
- The API to bind and create assembly programs makes sense, unlike
ARB_separate_shader_objects.

1 files changed, 11 insertions, 5 deletions

diff --git a/src/video_core/renderer_opengl/gl_rasterizer.h b/src/video_core/renderer_opengl/gl_rasterizer.h
index b94c65907..87f7fe159 100644
--- a/src/video_core/renderer_opengl/gl_rasterizer.h
+++ b/src/video_core/renderer_opengl/gl_rasterizer.h
@@ -56,8 +56,8 @@ struct DrawParameters;
 class RasterizerOpenGL : public VideoCore::RasterizerAccelerated {
 public:
     explicit RasterizerOpenGL(Core::System& system, Core::Frontend::EmuWindow& emu_window,
-                              ScreenInfo& info, GLShader::ProgramManager& program_manager,
-                              StateTracker& state_tracker);
+                              const Device& device, ScreenInfo& info,
+                              ProgramManager& program_manager, StateTracker& state_tracker);
     ~RasterizerOpenGL() override;
 
     void Draw(bool is_indexed, bool is_instanced) override;
@@ -106,7 +106,7 @@ private:
     void SetupComputeConstBuffers(const Shader& kernel);
 
     /// Configures a constant buffer.
-    void SetupConstBuffer(u32 binding, const Tegra::Engines::ConstBufferInfo& buffer,
+    void SetupConstBuffer(GLenum stage, u32 binding, const Tegra::Engines::ConstBufferInfo& buffer,
                           const ConstBufferEntry& entry);
 
     /// Configures the current global memory entries to use for the draw command.
@@ -224,7 +224,7 @@ private:
 
     void SetupShaders(GLenum primitive_mode);
 
-    const Device device;
+    const Device& device;
 
     TextureCacheOpenGL texture_cache;
     ShaderCacheOpenGL shader_cache;
@@ -236,7 +236,7 @@ private:
 
     Core::System& system;
     ScreenInfo& screen_info;
-    GLShader::ProgramManager& program_manager;
+    ProgramManager& program_manager;
     StateTracker& state_tracker;
 
     static constexpr std::size_t STREAM_BUFFER_SIZE = 128 * 1024 * 1024;
@@ -248,6 +248,12 @@ private:
     std::bitset<Tegra::Engines::Maxwell3D::Regs::NumTransformFeedbackBuffers>
         enabled_transform_feedback_buffers;
 
+    static constexpr std::size_t NUM_CONSTANT_BUFFERS =
+        Tegra::Engines::Maxwell3D::Regs::MaxConstBuffers *
+        Tegra::Engines::Maxwell3D::Regs::MaxShaderProgram;
+    std::array<GLuint, NUM_CONSTANT_BUFFERS> staging_cbufs{};
+    std::size_t current_cbuf = 0;
+
     /// Number of commands queued to the OpenGL driver. Reseted on flush.
     std::size_t num_queued_commands = 0;