From b9c55b5b9e983e446695f471aed1cdf14e14c88e Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@qt.io>
Date: Tue, 18 Jan 2022 22:02:20 +0100
Subject: [PATCH] QVersionNumber: de-inline QList constructor calls and
 resize()

The QList<int> range ctor and other QList<int> methods have percolated
up near the top of the list of Clang -ftime-trace most expensive
template instantiations in PCH libQt6Gui.so builds:

**** Templates that took longest to instantiate:
  [...]
  5138 ms: QList<int>::QList<const int *, true> (256 times, avg 20 ms)
  4327 ms: QtPrivate::QCommonArrayOps<int>::appendIteratorRange<const int *> (256 times, avg 16 ms)

The code in 6.3 is already sufficiently different for this patch to
not be applicable there.

Task-number: QTBUG-97601
Change-Id: I4420c8c90e472ecfd679b414cc4334d2ab55cce3
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
 src/corelib/tools/qversionnumber.cpp | 23 +++++++++++++++++++++++
 src/corelib/tools/qversionnumber.h   | 25 +++++++++++++------------
 2 files changed, 36 insertions(+), 12 deletions(-)

diff --git a/src/corelib/tools/qversionnumber.cpp b/src/corelib/tools/qversionnumber.cpp
index 6494603a11e..8002cc9d3f7 100644
--- a/src/corelib/tools/qversionnumber.cpp
+++ b/src/corelib/tools/qversionnumber.cpp
@@ -481,6 +481,29 @@ QVersionNumber QVersionNumber::fromString(QAnyStringView string, qsizetype *suff
     return string.visit([=] (auto string) { return from_string(string, suffixIndex); });
 }
 
+void QVersionNumber::SegmentStorage::setListData(const QList<int> &seg)
+{
+    pointer_segments = new QList<int>(seg);
+}
+
+void QVersionNumber::SegmentStorage::setListData(QList<int> &&seg)
+{
+    pointer_segments = new QList<int>(std::move(seg));
+}
+
+void QVersionNumber::SegmentStorage::setListData(const int *first, const int *last)
+{
+    pointer_segments = new QList<int>(first, last);
+}
+
+void QVersionNumber::SegmentStorage::resize(qsizetype len)
+{
+    if (isUsingPointer())
+        pointer_segments->resize(len);
+    else
+        setInlineSize(len);
+}
+
 void QVersionNumber::SegmentStorage::setVector(int len, int maj, int min, int mic)
 {
     pointer_segments = new QList<int>;
diff --git a/src/corelib/tools/qversionnumber.h b/src/corelib/tools/qversionnumber.h
index c00587c300e..e023810b403 100644
--- a/src/corelib/tools/qversionnumber.h
+++ b/src/corelib/tools/qversionnumber.h
@@ -96,13 +96,15 @@ class QVersionNumber
             if (dataFitsInline(seg.data(), seg.size()))
                 setInlineData(seg.data(), seg.size());
             else
-                pointer_segments = new QList<int>(seg);
+                setListData(seg);
         }
 
+        Q_CORE_EXPORT void setListData(const QList<int> &seg);
+
         SegmentStorage(const SegmentStorage &other)
         {
             if (other.isUsingPointer())
-                pointer_segments = new QList<int>(*other.pointer_segments);
+                setListData(*other.pointer_segments);
             else
                 dummy = other.dummy;
         }
@@ -112,7 +114,7 @@ class QVersionNumber
             if (isUsingPointer() && other.isUsingPointer()) {
                 *pointer_segments = *other.pointer_segments;
             } else if (other.isUsingPointer()) {
-                pointer_segments = new QList<int>(*other.pointer_segments);
+                setListData(*other.pointer_segments);
             } else {
                 if (isUsingPointer())
                     delete pointer_segments;
@@ -139,8 +141,11 @@ class QVersionNumber
             if (dataFitsInline(std::as_const(seg).data(), seg.size()))
                 setInlineData(std::as_const(seg).data(), seg.size());
             else
-                pointer_segments = new QList<int>(std::move(seg));
+                setListData(std::move(seg));
         }
+
+        Q_CORE_EXPORT void setListData(QList<int> &&seg);
+
         explicit SegmentStorage(std::initializer_list<int> args)
             : SegmentStorage(args.begin(), args.end()) {}
 
@@ -149,10 +154,12 @@ class QVersionNumber
             if (dataFitsInline(first, last - first)) {
                 setInlineData(first, last - first);
             } else {
-                pointer_segments = new QList<int>(first, last);
+                setListData(first, last);
             }
         }
 
+        Q_CORE_EXPORT void setListData(const int *first, const int *last);
+
         ~SegmentStorage() { if (isUsingPointer()) delete pointer_segments; }
 
         bool isUsingPointer() const noexcept
@@ -167,13 +174,7 @@ class QVersionNumber
             inline_segments[InlineSegmentMarker] = qint8(1 + 2 * len);
         }
 
-        void resize(qsizetype len)
-        {
-            if (isUsingPointer())
-                pointer_segments->resize(len);
-            else
-                setInlineSize(len);
-        }
+        Q_CORE_EXPORT void resize(qsizetype len);
 
         int at(qsizetype index) const
         {