[dynarmic, common] pagetable clustering (#3215)

Raises the size of each page entry to 32 bytes, however, it merges them into a single structure
THEORETICALLY this is better since the access pattern observed corresponds to the program wanting backing_addr/pointers/blocks immediately after one another.
This may improve performance at the cost of some extra memory.
Another implementation would be to structure only backing_addr/blocks within the same virtual buffer.
Alas spamming virtual buffers is evil since each of them is a cache trasher (imagine jumping from wildly different block to wildly different block immediately).

Signed-off-by: lizzie lizzie@eden-emu.dev

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3215
Reviewed-by: DraVee <dravee@eden-emu.dev>
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>
Co-authored-by: lizzie <lizzie@eden-emu.dev>
Co-committed-by: lizzie <lizzie@eden-emu.dev>

2 files changed, 32 insertions, 36 deletions

diff --git a/src/common/page_table.cpp b/src/common/page_table.cpp
index 3205eb7dab..d34ba89993 100644
--- a/src/common/page_table.cpp
+++ b/src/common/page_table.cpp
@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // SPDX-FileCopyrightText: Copyright 2019 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
@@ -22,37 +25,25 @@ bool PageTable::ContinueTraversal(TraversalEntry* out_entry, TraversalContext* c
     // Setup invalid defaults.
     out_entry->phys_addr = 0;
     out_entry->block_size = page_size;
-
-    // Regardless of whether the page was mapped, advance on exit.
-    SCOPE_EXIT {
-        context->next_page += 1;
-        context->next_offset += page_size;
-    };
-
     // Validate that we can read the actual entry.
-    const auto page = context->next_page;
-    if (page >= backing_addr.size()) {
-        return false;
+    if (auto const page = context->next_page; page < entries.size()) {
+        // Validate that the entry is mapped.
+        if (auto const paddr = entries[page].addr; paddr != 0) {
+            // Populate the results.
+            out_entry->phys_addr = paddr + context->next_offset;
+            context->next_page += 1;
+            context->next_offset += page_size;
+            return true;
+        }
     }
-
-    // Validate that the entry is mapped.
-    const auto phys_addr = backing_addr[page];
-    if (phys_addr == 0) {
-        return false;
-    }
-
-    // Populate the results.
-    out_entry->phys_addr = phys_addr + context->next_offset;
-
-    return true;
+    context->next_page += 1;
+    context->next_offset += page_size;
+    return false;
 }
 
 void PageTable::Resize(std::size_t address_space_width_in_bits, std::size_t page_size_in_bits) {
-    const std::size_t num_page_table_entries{1ULL
-                                             << (address_space_width_in_bits - page_size_in_bits)};
-    pointers.resize(num_page_table_entries);
-    backing_addr.resize(num_page_table_entries);
-    blocks.resize(num_page_table_entries);
+    auto const num_page_table_entries = 1ULL << (address_space_width_in_bits - page_size_in_bits);
+    entries.resize(num_page_table_entries);
     current_address_space_width_in_bits = address_space_width_in_bits;
     page_size = 1ULL << page_size_in_bits;
 }
diff --git a/src/common/page_table.h b/src/common/page_table.h
index 5340f7d863..3124b4a7fb 100644
--- a/src/common/page_table.h
+++ b/src/common/page_table.h
@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // SPDX-FileCopyrightText: Copyright 2019 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
@@ -75,7 +78,7 @@ struct PageTable {
 
         /// Write a page pointer and type pair atomically
         void Store(uintptr_t pointer, PageType type) noexcept {
-            raw.store(pointer | static_cast<uintptr_t>(type));
+            raw.store(pointer | uintptr_t(type));
         }
 
         /// Unpack a pointer from a page info raw representation
@@ -124,18 +127,20 @@ struct PageTable {
             return false;
         }
 
-        *out_phys_addr = backing_addr[virt_addr / page_size] + GetInteger(virt_addr);
+        *out_phys_addr = entries[virt_addr / page_size].addr + GetInteger(virt_addr);
         return true;
     }
 
-    /**
-     * Vector of memory pointers backing each page. An entry can only be non-null if the
-     * corresponding attribute element is of type `Memory`.
-     */
-    VirtualBuffer<PageInfo> pointers;
-    VirtualBuffer<u64> blocks;
-
-    VirtualBuffer<u64> backing_addr;
+    /// Vector of memory pointers backing each page. An entry can only be non-null if the
+    /// corresponding attribute element is of type `Memory`.
+    struct PageEntryData {
+        PageInfo ptr;
+        u64 block;
+        u64 addr;
+        u64 padding;
+    };
+    VirtualBuffer<PageEntryData> entries;
+    static_assert(sizeof(PageEntryData) == 32);
 
     std::size_t current_address_space_width_in_bits{};