From a398baae062052ff0951db97ab296a18b4dde507 Mon Sep 17 00:00:00 2001
From: Exverge <exverge@exverge.xyz>
Date: Wed, 29 Jul 2026 22:25:04 -0400
Subject: [PATCH] [large_vector] zero regions more efficiently

---
 src/common/sparse_large_vector.h | 34 ++++++++++++++++++++------------
 src/core/memory.cpp              |  6 +-----
 2 files changed, 22 insertions(+), 18 deletions(-)

diff --git a/src/common/sparse_large_vector.h b/src/common/sparse_large_vector.h
index 8e6639e16a..d360076de0 100644
--- a/src/common/sparse_large_vector.h
+++ b/src/common/sparse_large_vector.h
@@ -73,14 +73,6 @@ public:
         }
     }
 
-    /// Returns a pointer to the value of the requested index if that page has been allocated, or otherwise return nullptr.
-    T* GetNoFault(std::size_t index) const noexcept {
-        if (!IsCommittedPage(index)) {
-            return nullptr;
-        }
-        return &base_ptr[index];
-    }
-
     /// Returns a reference to the value of the requested index and allocates memory if needed.
     T& GetAndFault(std::size_t index) noexcept {
         if (index > alloc_size / sizeof(T)) {
@@ -114,13 +106,29 @@ public:
         base_ptr[index] = value;
     }
 
-    void Zero(std::size_t index) noexcept {
-        if (!IsCommittedPage(index)) {
+    void ZeroRegion(std::size_t start, std::size_t end_) noexcept {
+        u64 base = static_cast<u64>(start) * sizeof(T);
+        const u64 end = static_cast<u64>(end_) * sizeof(T);
+
+        const u64 end_page = AlignUp(base, HostPageSize);
+        const u64 first_size = std::min(end_page, end) - base;
+
+        if (IsCommittedPage(base / sizeof(T))) {
+            std::memset(reinterpret_cast<void*>(base), 0, first_size);
+        }
+
+        if (end <= end_page)
             return;
+
+        base = end_page;
+
+        for (u64 page = base; page < end; page += HostPageSize) {
+            if (!IsCommittedPage(page / sizeof(T))) {
+                continue;
+            }
+
+            std::memset(reinterpret_cast<void*>(page), 0, std::min( HostPageSize, end - page));
         }
-        // reinterpret_cast because C++ doesn't like memset'ing, but this should be valid
-        // because of std::is_trivially_copyable_v
-        std::memset(reinterpret_cast<void*>(&base_ptr[index]), 0, sizeof(T));
     }
 
     constexpr void CommitRegion(size_t index, size_t end_) {
diff --git a/src/core/memory.cpp b/src/core/memory.cpp
index 9b4e0d878b..a14ca07a7e 100644
--- a/src/core/memory.cpp
+++ b/src/core/memory.cpp
@@ -548,11 +548,7 @@ struct Memory::Impl {
             ASSERT_MSG(type != Common::PageType::Memory,
                        "Mapping memory page without a pointer @ {:016x}", base * YUZU_PAGESIZE);
 
-            while (base != end) {
-                // TODO: add a ZeroRegion function
-                page_table.entries.Zero(base);
-                base += 1;
-            }
+            page_table.entries.ZeroRegion(base, end);
         } else {
             auto orig_base = base;