From 65e646eeba53fe1067b7d69044ddabaee18d868f Mon Sep 17 00:00:00 2001
From: liamwhite <liamwhite@users.noreply.github.com>
Date: Sun, 17 Dec 2023 18:59:49 -0500
Subject: Revert "video_core: use interval map for page count tracking"

---
 src/video_core/rasterizer_accelerated.cpp | 99 +++++++++++++++----------------
 1 file changed, 47 insertions(+), 52 deletions(-)

(limited to 'src/video_core/rasterizer_accelerated.cpp')

diff --git a/src/video_core/rasterizer_accelerated.cpp b/src/video_core/rasterizer_accelerated.cpp
index 3c9477f6e..f200a650f 100644
--- a/src/video_core/rasterizer_accelerated.cpp
+++ b/src/video_core/rasterizer_accelerated.cpp
@@ -3,7 +3,6 @@
 
 #include <atomic>
 
-#include "common/alignment.h"
 #include "common/assert.h"
 #include "common/common_types.h"
 #include "common/div_ceil.h"
@@ -12,65 +11,61 @@
 
 namespace VideoCore {
 
-static constexpr u16 IdentityValue = 1;
-
 using namespace Core::Memory;
 
-RasterizerAccelerated::RasterizerAccelerated(Memory& cpu_memory_) : map{}, cpu_memory{cpu_memory_} {
-    // We are tracking CPU memory, which cannot map more than 39 bits.
-    const VAddr start_address = 0;
-    const VAddr end_address = (1ULL << 39);
-    const IntervalType address_space_interval(start_address, end_address);
-    const auto value = std::make_pair(address_space_interval, IdentityValue);
-
-    map.add(value);
-}
+RasterizerAccelerated::RasterizerAccelerated(Memory& cpu_memory_)
+    : cached_pages(std::make_unique<CachedPages>()), cpu_memory{cpu_memory_} {}
 
 RasterizerAccelerated::~RasterizerAccelerated() = default;
 
-void RasterizerAccelerated::UpdatePagesCachedCount(VAddr addr, u64 size, bool cache) {
-    std::scoped_lock lk{map_lock};
-
-    // Align sizes.
-    addr = Common::AlignDown(addr, YUZU_PAGESIZE);
-    size = Common::AlignUp(size, YUZU_PAGESIZE);
-
-    // Declare the overall interval we are going to operate on.
-    const VAddr start_address = addr;
-    const VAddr end_address = addr + size;
-    const IntervalType modification_range(start_address, end_address);
-
-    // Find the boundaries of where to iterate.
-    const auto lower = map.lower_bound(modification_range);
-    const auto upper = map.upper_bound(modification_range);
-
-    // Iterate over the contained intervals.
-    for (auto it = lower; it != upper; it++) {
-        // Intersect interval range with modification range.
-        const auto current_range = modification_range & it->first;
-
-        // Calculate the address and size to operate over.
-        const auto current_addr = current_range.lower();
-        const auto current_size = current_range.upper() - current_addr;
-
-        // Get the current value of the range.
-        const auto value = it->second;
+void RasterizerAccelerated::UpdatePagesCachedCount(VAddr addr, u64 size, int delta) {
+    u64 uncache_begin = 0;
+    u64 cache_begin = 0;
+    u64 uncache_bytes = 0;
+    u64 cache_bytes = 0;
+
+    std::atomic_thread_fence(std::memory_order_acquire);
+    const u64 page_end = Common::DivCeil(addr + size, YUZU_PAGESIZE);
+    for (u64 page = addr >> YUZU_PAGEBITS; page != page_end; ++page) {
+        std::atomic_uint16_t& count = cached_pages->at(page >> 2).Count(page);
+
+        if (delta > 0) {
+            ASSERT_MSG(count.load(std::memory_order::relaxed) < UINT16_MAX, "Count may overflow!");
+        } else if (delta < 0) {
+            ASSERT_MSG(count.load(std::memory_order::relaxed) > 0, "Count may underflow!");
+        } else {
+            ASSERT_MSG(false, "Delta must be non-zero!");
+        }
 
-        if (cache && value == IdentityValue) {
-            // If we are going to cache, and the value is not yet referenced, then cache this range.
-            cpu_memory.RasterizerMarkRegionCached(current_addr, current_size, true);
-        } else if (!cache && value == IdentityValue + 1) {
-            // If we are going to uncache, and this is the last reference, then uncache this range.
-            cpu_memory.RasterizerMarkRegionCached(current_addr, current_size, false);
+        // Adds or subtracts 1, as count is a unsigned 8-bit value
+        count.fetch_add(static_cast<u16>(delta), std::memory_order_release);
+
+        // Assume delta is either -1 or 1
+        if (count.load(std::memory_order::relaxed) == 0) {
+            if (uncache_bytes == 0) {
+                uncache_begin = page;
+            }
+            uncache_bytes += YUZU_PAGESIZE;
+        } else if (uncache_bytes > 0) {
+            cpu_memory.RasterizerMarkRegionCached(uncache_begin << YUZU_PAGEBITS, uncache_bytes,
+                                                  false);
+            uncache_bytes = 0;
+        }
+        if (count.load(std::memory_order::relaxed) == 1 && delta > 0) {
+            if (cache_bytes == 0) {
+                cache_begin = page;
+            }
+            cache_bytes += YUZU_PAGESIZE;
+        } else if (cache_bytes > 0) {
+            cpu_memory.RasterizerMarkRegionCached(cache_begin << YUZU_PAGEBITS, cache_bytes, true);
+            cache_bytes = 0;
         }
     }
-
-    // Update the set.
-    const auto value = std::make_pair(modification_range, IdentityValue);
-    if (cache) {
-        map.add(value);
-    } else {
-        map.subtract(value);
+    if (uncache_bytes > 0) {
+        cpu_memory.RasterizerMarkRegionCached(uncache_begin << YUZU_PAGEBITS, uncache_bytes, false);
+    }
+    if (cache_bytes > 0) {
+        cpu_memory.RasterizerMarkRegionCached(cache_begin << YUZU_PAGEBITS, cache_bytes, true);
     }
 }
 
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