shader_cache: Implement a generic shader cache

Implement a generic shader cache for fast lookups and invalidations.
Invalidations are cheap but expensive when a shader is invalidated.

Use two mutexes instead of one to avoid locking invalidations for
lookups and vice versa. When a shader has to be removed, lookups are
locked as expected.

2 files changed, 229 insertions, 0 deletions

diff --git a/src/video_core/CMakeLists.txt b/src/video_core/CMakeLists.txt
index 2bf8d68ce..cf1885f92 100644
--- a/src/video_core/CMakeLists.txt
+++ b/src/video_core/CMakeLists.txt
@@ -93,6 +93,7 @@ add_library(video_core STATIC
     renderer_opengl/utils.h
     sampler_cache.cpp
     sampler_cache.h
+    shader_cache.h
     shader/decode/arithmetic.cpp
     shader/decode/arithmetic_immediate.cpp
     shader/decode/bfe.cpp
diff --git a/src/video_core/shader_cache.h b/src/video_core/shader_cache.h
new file mode 100644
index 000000000..a23c23886
--- /dev/null
+++ b/src/video_core/shader_cache.h
@@ -0,0 +1,228 @@
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <algorithm>
+#include <memory>
+#include <mutex>
+#include <unordered_map>
+#include <utility>
+#include <vector>
+
+#include "common/assert.h"
+#include "common/common_types.h"
+#include "video_core/rasterizer_interface.h"
+
+namespace VideoCommon {
+
+template <class T>
+class ShaderCache {
+    static constexpr u64 PAGE_SHIFT = 14;
+
+    struct Entry {
+        VAddr addr_start;
+        VAddr addr_end;
+        T* data;
+
+        bool is_memory_marked = true;
+
+        constexpr bool Overlaps(VAddr start, VAddr end) const noexcept {
+            return start < addr_end && addr_start < end;
+        }
+    };
+
+public:
+    virtual ~ShaderCache() = default;
+
+    /// @brief Removes shaders inside a given region
+    /// @note Checks for ranges
+    /// @param addr Start address of the invalidation
+    /// @param size Number of bytes of the invalidation
+    void InvalidateRegion(VAddr addr, std::size_t size) {
+        std::scoped_lock lock{invalidation_mutex};
+        InvalidatePagesInRegion(addr, size);
+        RemovePendingShaders();
+    }
+
+    /// @brief Unmarks a memory region as cached and marks it for removal
+    /// @param addr Start address of the CPU write operation
+    /// @param size Number of bytes of the CPU write operation
+    void OnCPUWrite(VAddr addr, std::size_t size) {
+        std::lock_guard lock{invalidation_mutex};
+        InvalidatePagesInRegion(addr, size);
+    }
+
+    /// @brief Flushes delayed removal operations
+    void SyncGuestHost() {
+        std::scoped_lock lock{invalidation_mutex};
+        RemovePendingShaders();
+    }
+
+    /// @brief Tries to obtain a cached shader starting in a given address
+    /// @note Doesn't check for ranges, the given address has to be the start of the shader
+    /// @param addr Start address of the shader, this doesn't cache for region
+    /// @return Pointer to a valid shader, nullptr when nothing is found
+    T* TryGet(VAddr addr) const {
+        std::scoped_lock lock{lookup_mutex};
+
+        const auto it = lookup_cache.find(addr);
+        if (it == lookup_cache.end()) {
+            return nullptr;
+        }
+        return it->second->data;
+    }
+
+protected:
+    explicit ShaderCache(VideoCore::RasterizerInterface& rasterizer_) : rasterizer{rasterizer_} {}
+
+    /// @brief Register in the cache a given entry
+    /// @param data Shader to store in the cache
+    /// @param addr Start address of the shader that will be registered
+    /// @param size Size in bytes of the shader
+    void Register(std::unique_ptr<T> data, VAddr addr, std::size_t size) {
+        std::scoped_lock lock{invalidation_mutex, lookup_mutex};
+
+        const VAddr addr_end = addr + size;
+        Entry* const entry = NewEntry(addr, addr_end, data.get());
+
+        const u64 page_end = addr_end >> PAGE_SHIFT;
+        for (u64 page = addr >> PAGE_SHIFT; page <= page_end; ++page) {
+            invalidation_cache[page].push_back(entry);
+        }
+
+        storage.push_back(std::move(data));
+
+        rasterizer.UpdatePagesCachedCount(addr, size, 1);
+    }
+
+    /// @brief Called when a shader is going to be removed
+    /// @param shader Shader that will be removed
+    /// @pre invalidation_cache is locked
+    /// @pre lookup_mutex is locked
+    virtual void OnShaderRemoval([[maybe_unused]] T* shader) {}
+
+private:
+    /// @brief Invalidate pages in a given region
+    /// @pre invalidation_mutex is locked
+    void InvalidatePagesInRegion(VAddr addr, std::size_t size) {
+        const VAddr addr_end = addr + size;
+        const u64 page_end = addr_end >> PAGE_SHIFT;
+        for (u64 page = addr >> PAGE_SHIFT; page <= page_end; ++page) {
+            const auto it = invalidation_cache.find(page);
+            if (it == invalidation_cache.end()) {
+                continue;
+            }
+
+            std::vector<Entry*>& entries = it->second;
+            InvalidatePageEntries(entries, addr, addr_end);
+
+            // If there's nothing else in this page, remove it to avoid overpopulating the hash map.
+            if (entries.empty()) {
+                invalidation_cache.erase(it);
+            }
+        }
+    }
+
+    /// @brief Remove shaders marked for deletion
+    /// @pre invalidation_mutex is locked
+    void RemovePendingShaders() {
+        if (marked_for_removal.empty()) {
+            return;
+        }
+        std::scoped_lock lock{lookup_mutex};
+
+        std::vector<T*> removed_shaders;
+        removed_shaders.reserve(marked_for_removal.size());
+
+        for (Entry* const entry : marked_for_removal) {
+            if (lookup_cache.erase(entry->addr_start) > 0) {
+                removed_shaders.push_back(entry->data);
+            }
+        }
+        marked_for_removal.clear();
+
+        if (!removed_shaders.empty()) {
+            RemoveShadersFromStorage(std::move(removed_shaders));
+        }
+    }
+
+    /// @brief Invalidates entries in a given range for the passed page
+    /// @param entries         Vector of entries in the page, it will be modified on overlaps
+    /// @param addr            Start address of the invalidation
+    /// @param addr_end        Non-inclusive end address of the invalidation
+    /// @pre invalidation_mutex is locked
+    void InvalidatePageEntries(std::vector<Entry*>& entries, VAddr addr, VAddr addr_end) {
+        auto it = entries.begin();
+        while (it != entries.end()) {
+            Entry* const entry = *it;
+            if (!entry->Overlaps(addr, addr_end)) {
+                ++it;
+                continue;
+            }
+            UnmarkMemory(entry);
+            marked_for_removal.push_back(entry);
+
+            it = entries.erase(it);
+        }
+    }
+
+    /// @brief Unmarks an entry from the rasterizer cache
+    /// @param entry Entry to unmark from memory
+    void UnmarkMemory(Entry* entry) {
+        if (!entry->is_memory_marked) {
+            return;
+        }
+        entry->is_memory_marked = false;
+
+        const VAddr addr = entry->addr_start;
+        const std::size_t size = entry->addr_end - addr;
+        rasterizer.UpdatePagesCachedCount(addr, size, -1);
+    }
+
+    /// @brief Removes a vector of shaders from a list
+    /// @param removed_shaders Shaders to be removed from the storage, it can contain duplicates
+    /// @pre invalidation_mutex is locked
+    /// @pre lookup_mutex is locked
+    void RemoveShadersFromStorage(std::vector<T*> removed_shaders) {
+        // Remove duplicates
+        std::sort(removed_shaders.begin(), removed_shaders.end());
+        removed_shaders.erase(std::unique(removed_shaders.begin(), removed_shaders.end()),
+                              removed_shaders.end());
+
+        // Now that there are no duplicates, we can notify removals
+        for (T* const shader : removed_shaders) {
+            OnShaderRemoval(shader);
+        }
+
+        // Remove them from the cache
+        const auto is_removed = [&removed_shaders](std::unique_ptr<T>& shader) {
+            return std::find(removed_shaders.begin(), removed_shaders.end(), shader.get()) !=
+                   removed_shaders.end();
+        };
+        storage.erase(std::remove_if(storage.begin(), storage.end(), is_removed), storage.end());
+    }
+
+    /// @brief Creates a new entry in the lookup cache and returns its pointer
+    /// @pre lookup_mutex is locked
+    Entry* NewEntry(VAddr addr, VAddr addr_end, T* data) {
+        auto entry = std::make_unique<Entry>(Entry{addr, addr_end, data});
+        Entry* const entry_pointer = entry.get();
+
+        lookup_cache.emplace(addr, std::move(entry));
+        return entry_pointer;
+    }
+
+    VideoCore::RasterizerInterface& rasterizer;
+
+    mutable std::mutex lookup_mutex;
+    std::mutex invalidation_mutex;
+
+    std::unordered_map<u64, std::unique_ptr<Entry>> lookup_cache;
+    std::unordered_map<u64, std::vector<Entry*>> invalidation_cache;
+    std::vector<std::unique_ptr<T>> storage;
+    std::vector<Entry*> marked_for_removal;
+};
+
+} // namespace VideoCommon