shader/texture: Join separate image and sampler pairs offline

Games using D3D idioms can join images and samplers when a shader
executes, instead of baking them into a combined sampler image. This is
also possible on Vulkan.

One approach to this solution would be to use separate samplers on
Vulkan and leave this unimplemented on OpenGL, but we can't do this
because there's no consistent way of determining which constant buffer
holds a sampler and which one an image. We could in theory find the
first bit and if it's in the TIC area, it's an image; but this falls
apart when an image or sampler handle use an index of zero.

The used approach is to track for a LOP.OR operation (this is done at an
IR level, not at an ISA level), track again the constant buffers used as
source and store this pair. Then, outside of shader execution, join
the sample and image pair with a bitwise or operation.

This approach won't work on games that truly use separate samplers in a
meaningful way. For example, pooling textures in a 2D array and
determining at runtime what sampler to use.

This invalidates OpenGL's disk shader cache :)

- Used mostly by D3D ports to Switch

1 files changed, 32 insertions, 43 deletions

diff --git a/src/video_core/shader/node.h b/src/video_core/shader/node.h
index c5e5165ff..8f230d57a 100644
--- a/src/video_core/shader/node.h
+++ b/src/video_core/shader/node.h
@@ -275,10 +275,11 @@ using Node = std::shared_ptr<NodeData>;
 using Node4 = std::array<Node, 4>;
 using NodeBlock = std::vector<Node>;
 
-class BindlessSamplerNode;
-class ArraySamplerNode;
+struct ArraySamplerNode;
+struct BindlessSamplerNode;
+struct SeparateSamplerNode;
 
-using TrackSamplerData = std::variant<BindlessSamplerNode, ArraySamplerNode>;
+using TrackSamplerData = std::variant<BindlessSamplerNode, SeparateSamplerNode, ArraySamplerNode>;
 using TrackSampler = std::shared_ptr<TrackSamplerData>;
 
 struct Sampler {
@@ -288,63 +289,51 @@ struct Sampler {
         : index{index}, offset{offset}, type{type}, is_array{is_array}, is_shadow{is_shadow},
           is_buffer{is_buffer}, is_indexed{is_indexed} {}
 
+    /// Separate sampler constructor
+    constexpr explicit Sampler(u32 index, std::pair<u32, u32> offsets, std::pair<u32, u32> buffers,
+                               Tegra::Shader::TextureType type, bool is_array, bool is_shadow,
+                               bool is_buffer)
+        : index{index}, offset{offsets.first}, secondary_offset{offsets.second},
+          buffer{buffers.first}, secondary_buffer{buffers.second}, type{type}, is_array{is_array},
+          is_shadow{is_shadow}, is_buffer{is_buffer}, is_separated{true} {}
+
     /// Bindless samplers constructor
     constexpr explicit Sampler(u32 index, u32 offset, u32 buffer, Tegra::Shader::TextureType type,
                                bool is_array, bool is_shadow, bool is_buffer, bool is_indexed)
         : index{index}, offset{offset}, buffer{buffer}, type{type}, is_array{is_array},
           is_shadow{is_shadow}, is_buffer{is_buffer}, is_bindless{true}, is_indexed{is_indexed} {}
 
-    u32 index = 0;  ///< Emulated index given for the this sampler.
-    u32 offset = 0; ///< Offset in the const buffer from where the sampler is being read.
-    u32 buffer = 0; ///< Buffer where the bindless sampler is being read (unused on bound samplers).
-    u32 size = 1;   ///< Size of the sampler.
+    u32 index = 0;            ///< Emulated index given for the this sampler.
+    u32 offset = 0;           ///< Offset in the const buffer from where the sampler is being read.
+    u32 secondary_offset = 0; ///< Secondary offset in the const buffer.
+    u32 buffer = 0;           ///< Buffer where the bindless sampler is read.
+    u32 secondary_buffer = 0; ///< Secondary buffer where the bindless sampler is read.
+    u32 size = 1;             ///< Size of the sampler.
 
     Tegra::Shader::TextureType type{}; ///< The type used to sample this texture (Texture2D, etc)
-    bool is_array = false;    ///< Whether the texture is being sampled as an array texture or not.
-    bool is_shadow = false;   ///< Whether the texture is being sampled as a depth texture or not.
-    bool is_buffer = false;   ///< Whether the texture is a texture buffer without sampler.
-    bool is_bindless = false; ///< Whether this sampler belongs to a bindless texture or not.
-    bool is_indexed = false;  ///< Whether this sampler is an indexed array of textures.
+    bool is_array = false;     ///< Whether the texture is being sampled as an array texture or not.
+    bool is_shadow = false;    ///< Whether the texture is being sampled as a depth texture or not.
+    bool is_buffer = false;    ///< Whether the texture is a texture buffer without sampler.
+    bool is_bindless = false;  ///< Whether this sampler belongs to a bindless texture or not.
+    bool is_indexed = false;   ///< Whether this sampler is an indexed array of textures.
+    bool is_separated = false; ///< Whether the image and sampler is separated or not.
 };
 
 /// Represents a tracked bindless sampler into a direct const buffer
-class ArraySamplerNode final {
-public:
-    explicit ArraySamplerNode(u32 index, u32 base_offset, u32 bindless_var)
-        : index{index}, base_offset{base_offset}, bindless_var{bindless_var} {}
-
-    constexpr u32 GetIndex() const {
-        return index;
-    }
-
-    constexpr u32 GetBaseOffset() const {
-        return base_offset;
-    }
-
-    constexpr u32 GetIndexVar() const {
-        return bindless_var;
-    }
-
-private:
+struct ArraySamplerNode {
     u32 index;
     u32 base_offset;
     u32 bindless_var;
 };
 
-/// Represents a tracked bindless sampler into a direct const buffer
-class BindlessSamplerNode final {
-public:
-    explicit BindlessSamplerNode(u32 index, u32 offset) : index{index}, offset{offset} {}
-
-    constexpr u32 GetIndex() const {
-        return index;
-    }
-
-    constexpr u32 GetOffset() const {
-        return offset;
-    }
+/// Represents a tracked separate sampler image pair that was folded statically
+struct SeparateSamplerNode {
+    std::pair<u32, u32> indices;
+    std::pair<u32, u32> offsets;
+};
 
-private:
+/// Represents a tracked bindless sampler into a direct const buffer
+struct BindlessSamplerNode {
     u32 index;
     u32 offset;
 };