QLibrary: find AVX2 (Haswell) optimized plugins and libraries

Libraries are placed in a subdir "haswell/" of the main library dir,
whereas plugins are simply named with ".avx2" appended to the plugin
name (plugin.so.avx2). The "haswell/" library directory suffix is a
convention found in glibc since version 2.26, whereas the ".avx2" and
".avx512" suffixes are a convention found in the Clear Linux OS for
Intel Architecture.

This patch implements this for all Unix OSes, except for Darwin, where
the fat file format already has a sub-architecture for Haswell
(x86_64h).

We could also implement the "sse2/" subdir search for libraries, but I
don't think it's worth the cost in 2018.

Change-Id: Iff4151c519c144d580c4fffd1539fe5ee9a4d7b1
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/src/corelib/plugin/qfactoryloader.cpp b/src/corelib/plugin/qfactoryloader.cpp
index a40ba575fd..ec6d98cc3c 100644
--- a/src/corelib/plugin/qfactoryloader.cpp
+++ b/src/corelib/plugin/qfactoryloader.cpp
@@ -133,6 +133,11 @@ void QFactoryLoader::update()
             // versions of the same Qt libraries (due to the plugin's dependencies).
             if (isDebugPlugin != isDebugLibrary)
                 continue;
+#elif defined(Q_PROCESSOR_X86)
+            if (fileName.endsWith(QLatin1String(".avx2")) || fileName.endsWith(QLatin1String(".avx512"))) {
+                // ignore AVX2-optimized file, we'll do a bait-and-switch to it later
+                continue;
+            }
 #endif
             if (qt_debug_component()) {
                 qDebug() << "QFactoryLoader::QFactoryLoader() looking at" << fileName;