CpuId: call init whenever a user includes Vc/cpuid.h

Make sure it's called only once, though, and not from every single TU
that included Vc/cpuid.h.

Fixes: VcDevelgh-114
Signed-off-by: Matthias Kretz <kretz@kde.org>

examples/cpuid/main.cpp

@@ -31,7 +31,6 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 int Vc_CDECL main()
 {
     using Vc::CpuId;
-    CpuId::init();
     std::cout << "        cacheLineSize: " << CpuId::cacheLineSize() << '\n';
     std::cout << "        processorType: " << CpuId::processorType() << '\n';
     std::cout << "      processorFamily: " << CpuId::processorFamily() << '\n';

include/Vc/cpuid.h

@@ -249,6 +249,21 @@ class CpuId
         static bool   s_noL2orL3;
 };
 
+#ifndef Vc_COMPILE_LIB
+namespace detail
+{
+template <int = 0> struct RunCpuIdInit {
+    RunCpuIdInit() { CpuId::init(); }
+    static RunCpuIdInit tmp;
+};
+template <int N> RunCpuIdInit<N> RunCpuIdInit<N>::tmp;
+namespace
+{
+static auto ctor = RunCpuIdInit<>::tmp;
+}  // unnamed namespace
+}  // namespace detail
+#endif
+
 }
 
 #endif // VC_CPUID_H_

tests/linkTest1.cpp

@@ -22,5 +22,5 @@ int Vc_CDECL main()
 {
     float_v x = float_v::Random();
     x = fooLib0A(fooLib0B(fooLib1A(fooLib1B(fooLib2(fooLib3(foo0(foo1(x))))))));
-    return static_cast<int>(x.sum());
+    return static_cast<int>(x.sum()) >> 8;
 }

tests/linkTestLib0.cpp

@@ -1,5 +1,6 @@
 #include <Vc/Vc>
 #include <Vc/IO>
+#include <Vc/support.h>
 
 #define CAT(a, b) a##b
 #define name(a, b) CAT(a, b)

tests/linkTestLib1.cpp

@@ -1,5 +1,6 @@
 #include <Vc/Vc>
 #include <Vc/IO>
+#include <Vc/support.h>
 
 #define CAT(a, b) a##b
 #define name(a, b) CAT(a, b)