Incorrect using __cpuidex intrinsic under MSVC

[alukutkin]

Hello.
In function simdpp::detail::get_cpuid i found one little error with big effects.

Original code:

...
#elif _MSC_VER
    uint32_t regs[4];
    __cpuidex((int*) regs, subleaf, level);
    *eax = regs[0];
    *ebx = regs[1];
    *ecx = regs[2];
    *edx = regs[3];
#else
...

But if you'll see MSDN (https://msdn.microsoft.com/ru-ru/library/hskdteyh.aspx) you can notice what subleaf and level params followed in the wrong order. If you change that order all works as intended.

You can use some simple test:

#include <iostream>
#include <simdpp/simd.h>
#include <simdpp/dispatch/get_arch_raw_cpuid.h>

#define SIMDPP_USER_ARCH_INFO ::simdpp::get_arch_raw_cpuid()

namespace SIMDPP_ARCH_NAMESPACE {
std::string archToString(simdpp::Arch arch)
{
    std::string ret = "none";

    if ((arch & simdpp::Arch::X86_SSE2) == simdpp::Arch::X86_SSE2)
        ret += " sse2";
    if ((arch & simdpp::Arch::X86_SSE3) == simdpp::Arch::X86_SSE3)
        ret += " sse3";
    if ((arch & simdpp::Arch::X86_SSSE3) == simdpp::Arch::X86_SSSE3)
        ret += " ssse3";
    if ((arch & simdpp::Arch::X86_SSE4_1) == simdpp::Arch::X86_SSE4_1)
        ret += " sse4.1";
    if ((arch & simdpp::Arch::X86_FMA3) == simdpp::Arch::X86_FMA3)
        ret += " fma3";
    if ((arch & simdpp::Arch::X86_FMA4) == simdpp::Arch::X86_FMA4)
        ret += " fma4";
    if ((arch & simdpp::Arch::X86_XOP) == simdpp::Arch::X86_XOP)
        ret += " xop";
    if ((arch & simdpp::Arch::X86_AVX) == simdpp::Arch::X86_AVX)
        ret += " avx";
    if ((arch & simdpp::Arch::X86_AVX2) == simdpp::Arch::X86_AVX2)
        ret += " avx2";
    if ((arch & simdpp::Arch::X86_AVX512F) == simdpp::Arch::X86_AVX512F)
        ret += " avx512f";

    return ret;
}

void printArch()
{
    std::cout << "cpu arch: " << archToString(SIMDPP_USER_ARCH_INFO).c_str();
    std::cout << std::endl;

    std::cout << "compile arch: " << archToString(simdpp::this_compile_arch()).c_str();
    std::cout << std::endl;
}

} // namespace SIMDPP_ARCH_NAMESPACE

SIMDPP_MAKE_DISPATCHER_VOID0(printArch)

I'm tested it on Microsoft C++ Build Tools (based on MSVC 2015 SP3) with my i5-4460 CPU.

Output before fix:

cpu arch: none fma3
compile arch: none

Output after fix:

cpu arch: none sse2 sse3 ssse3 sse4.1 fma3 avx avx2
compile arch: none sse2 sse3 ssse3 sse4.1 fma3 avx

Sorry me, but I can't create pull request at that time :(

[alukutkin]

I added pull requests to fix that problem in master and cxx98 branches

[p12tic]

Thanks a lot. I'll merge them when I find out why the test farm hasn't caught the bug and update the tests.

[p12tic]

Fixes have been merged to both master and cxx98 branches. Thanks!