From 9bcb73af22749534abd255a554c43b41bacdc0be Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@qt.io>
Date: Thu, 8 Sep 2022 16:46:13 +0200
Subject: [PATCH] Specialize qMulOverflow<2>(n) as qAddOverflow(n, n)

Addition is always more efficient than multiplication.

Task-number: QTBUG-104972
Change-Id: Ib945e7df88562a2f4aea00aa319ff837191b8df2
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
(cherry picked from commit 4b5b87c27b803c5bf0fed96c381c5e343b28d419)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 src/corelib/global/qnumeric.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/corelib/global/qnumeric.h b/src/corelib/global/qnumeric.h
index d3a74a33e57..337f1e8118b 100644
--- a/src/corelib/global/qnumeric.h
+++ b/src/corelib/global/qnumeric.h
@@ -312,6 +312,8 @@ template <typename T, T V2> bool qMulOverflow(T v1, std::integral_constant<T, V2
 
 template <auto V2, typename T> bool qMulOverflow(T v1, T *r)
 {
+    if constexpr (V2 == 2)
+        return qAddOverflow(v1, v1, r);
     return qMulOverflow(v1, std::integral_constant<T, V2>{}, r);
 }