gl_shader_manager: Remove reliance on global accessor within MaxwellUniformData::SetFromRegs()

We can just pass in the Maxwell3D instance instead of going through the
system class to get at it.

This also lets us simplify the interface a little bit. Since we pass in
the Maxwell3D context now, we only really need to pass the shader stage
index value in.

src/video_core/renderer_opengl/gl_rasterizer.cpp

@@ -320,7 +320,7 @@ void RasterizerOpenGL::SetupShaders(GLenum primitive_mode) {
         const std::size_t stage{index == 0 ? 0 : index - 1}; // Stage indices are 0 - 5
 
         GLShader::MaxwellUniformData ubo{};
-        ubo.SetFromRegs(gpu.state.shader_stages[stage]);
+        ubo.SetFromRegs(gpu, stage);
         const GLintptr offset = buffer_cache.UploadHostMemory(
             &ubo, sizeof(ubo), static_cast<std::size_t>(uniform_buffer_alignment));
 

src/video_core/renderer_opengl/gl_shader_manager.cpp

@@ -2,15 +2,13 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
-#include "core/core.h"
 #include "video_core/renderer_opengl/gl_shader_manager.h"
 
 namespace OpenGL::GLShader {
 
-void MaxwellUniformData::SetFromRegs(const Maxwell3D::State::ShaderStageInfo& shader_stage) {
-    const auto& gpu = Core::System::GetInstance().GPU().Maxwell3D();
-    const auto& regs = gpu.regs;
-    const auto& state = gpu.state;
+void MaxwellUniformData::SetFromRegs(const Maxwell3D& maxwell, std::size_t shader_stage) {
+    const auto& regs = maxwell.regs;
+    const auto& state = maxwell.state;
 
     // TODO(bunnei): Support more than one viewport
     viewport_flip[0] = regs.viewport_transform[0].scale_x < 0.0 ? -1.0f : 1.0f;
@@ -31,8 +29,9 @@ void MaxwellUniformData::SetFromRegs(const Maxwell3D::State::ShaderStageInfo& sh
 
     // Assign in which stage the position has to be flipped
     // (the last stage before the fragment shader).
-    if (gpu.regs.shader_config[static_cast<u32>(Maxwell3D::Regs::ShaderProgram::Geometry)].enable) {
-        flip_stage = static_cast<u32>(Maxwell3D::Regs::ShaderProgram::Geometry);
+    constexpr u32 geometry_index = static_cast<u32>(Maxwell3D::Regs::ShaderProgram::Geometry);
+    if (maxwell.regs.shader_config[geometry_index].enable) {
+        flip_stage = geometry_index;
     } else {
         flip_stage = static_cast<u32>(Maxwell3D::Regs::ShaderProgram::VertexB);
     }

src/video_core/renderer_opengl/gl_shader_manager.h

@@ -19,7 +19,8 @@ using Tegra::Engines::Maxwell3D;
 ///       the end of a uniform block is included in UNIFORM_BLOCK_DATA_SIZE or not.
 ///       Not following that rule will cause problems on some AMD drivers.
 struct MaxwellUniformData {
-    void SetFromRegs(const Maxwell3D::State::ShaderStageInfo& shader_stage);
+    void SetFromRegs(const Maxwell3D& maxwell, std::size_t shader_stage);
+
     alignas(16) GLvec4 viewport_flip;
     struct alignas(16) {
         GLuint instance_id;