From d08f59d083c0d915bbd0d74972ee380763447f3d Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira@intel.com>
Date: Mon, 31 Jan 2022 14:47:46 -0800
Subject: qsimd: simplify the code slightly

Only x86 requires more than 32 different bits in the CPU feature
variable, so enforce the need for 64-bit atomics only for it. Everyone
else can stick to 32-bit atomics, which are supported everywhere.

Change-Id: I54f205f6b7314351b078fffd16cf7c7d50a84102
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
---
 src/corelib/global/qsimd.cpp | 13 +++----------
 src/corelib/global/qsimd_p.h | 10 ++++------
 2 files changed, 7 insertions(+), 16 deletions(-)

diff --git a/src/corelib/global/qsimd.cpp b/src/corelib/global/qsimd.cpp
index 5692b6ef03..8ff98ec7cd 100644
--- a/src/corelib/global/qsimd.cpp
+++ b/src/corelib/global/qsimd.cpp
@@ -1,7 +1,7 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
-** Copyright (C) 2019 Intel Corporation.
+** Copyright (C) 2021 The Qt Company Ltd.
+** Copyright (C) 2022 Intel Corporation.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the QtCore module of the Qt Toolkit.
@@ -583,11 +583,7 @@ static const int features_count = (sizeof features_indices) / (sizeof features_i
 // record what CPU features were enabled by default in this Qt build
 static const quint64 minFeature = qCompilerCpuFeatures;
 
-#ifdef Q_ATOMIC_INT64_IS_SUPPORTED
-Q_CORE_EXPORT QBasicAtomicInteger<quint64> qt_cpu_features[1] = { Q_BASIC_ATOMIC_INITIALIZER(0) };
-#else
-Q_CORE_EXPORT QBasicAtomicInteger<unsigned> qt_cpu_features[2] = { Q_BASIC_ATOMIC_INITIALIZER(0), Q_BASIC_ATOMIC_INITIALIZER(0) };
-#endif
+QBasicAtomicInteger<QCpuFeatureType> qt_cpu_features[1] = { 0 };
 
 quint64 qDetectCpuFeatures()
 {
@@ -626,9 +622,6 @@ quint64 qDetectCpuFeatures()
     }
 
     qt_cpu_features[0].storeRelaxed(f | quint32(QSimdInitialized));
-#ifndef Q_ATOMIC_INT64_IS_SUPPORTED
-    qt_cpu_features[1].storeRelaxed(f >> 32);
-#endif
     return f;
 }
 
diff --git a/src/corelib/global/qsimd_p.h b/src/corelib/global/qsimd_p.h
index 57ef30d567..cb02b31990 100644
--- a/src/corelib/global/qsimd_p.h
+++ b/src/corelib/global/qsimd_p.h
@@ -357,11 +357,12 @@ static const quint64 qCompilerCpuFeatures = 0
         ;
 #endif
 
-#ifdef Q_ATOMIC_INT64_IS_SUPPORTED
-extern Q_CORE_EXPORT QBasicAtomicInteger<quint64> qt_cpu_features[1];
+#ifdef Q_PROCESSOR_X86
+using QCpuFeatureType = quint64;
 #else
-extern Q_CORE_EXPORT QBasicAtomicInteger<unsigned> qt_cpu_features[2];
+using QCpuFeatureType = unsigned;
 #endif
+extern Q_CORE_EXPORT QBasicAtomicInteger<QCpuFeatureType> qt_cpu_features[1];
 Q_CORE_EXPORT quint64 qDetectCpuFeatures();
 
 #if defined(Q_PROCESSOR_X86) && QT_COMPILER_SUPPORTS_HERE(RDRND) && !defined(QT_BOOTSTRAPPED)
@@ -376,9 +377,6 @@ static inline qsizetype qRandomCpu(void *, qsizetype) noexcept
 static inline quint64 qCpuFeatures()
 {
     quint64 features = qt_cpu_features[0].loadRelaxed();
-#ifndef Q_ATOMIC_INT64_IS_SUPPORTED
-    features |= quint64(qt_cpu_features[1].loadRelaxed()) << 32;
-#endif
     if (Q_UNLIKELY(features == 0)) {
         features = qDetectCpuFeatures();
         Q_ASSUME(features != 0);
-- 
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