From d34d035022f9c7b9957cfb2abe0ba90486416ae2 Mon Sep 17 00:00:00 2001
From: Ulf Hermann <ulf.hermann@qt.io>
Date: Thu, 26 Jan 2023 14:16:35 +0100
Subject: [PATCH] MemoryManager: Retain the end of a chunk when allocating a
 new one

When we allocate a new chunk of memory, there may still be a bit of
memory left at the end of the previous one. Throwing that away is a
waste.

Change-Id: I2b70b581cb835161b0819c3e11c2354010c6ca1c
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
---
 src/qml/memory/qv4mm.cpp | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/qml/memory/qv4mm.cpp b/src/qml/memory/qv4mm.cpp
index a7892e9729..5c3be27014 100644
--- a/src/qml/memory/qv4mm.cpp
+++ b/src/qml/memory/qv4mm.cpp
@@ -522,6 +522,14 @@ HeapItem *BlockAllocator::allocate(size_t size, bool forceAllocation) {
     if (!m) {
         if (!forceAllocation)
             return nullptr;
+        if (nFree) {
+            // Save any remaining slots of the current chunk
+            // for later, smaller allocations.
+            size_t bin = binForSlots(nFree);
+            nextFree->freeData.next = freeBins[bin];
+            nextFree->freeData.availableSlots = nFree;
+            freeBins[bin] = nextFree;
+        }
         Chunk *newChunk = chunkAllocator->allocate();
         Q_V4_PROFILE_ALLOC(engine, Chunk::DataSize, Profiling::HeapPage);
         chunks.push_back(newChunk);