[Bug c++/90492] New: simple array-copy not use available simd-registers

[g.peterh...@t-online.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90492

            Bug ID: 90492
           Summary: simple array-copy not use available simd-registers
           Product: gcc
           Version: 8.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: g.peterh...@t-online.de
  Target Milestone: ---

snip

#include <array>
#include <iostream>

int main(const int argc, const char** argv)
{
        using value_type = int; // type does not matter
        using array_type = std::array<value_type, 32>;

        array_type      a, b;

        // simple init
        for (size_t i=0; i<a.size(); ++i)
                a[i] = argc;

        /*
         * copy's use only sse-registers and never higher
         */
        b = a;

        // or

        for (size_t i=0; i<a.size(); ++i)
                b[i] = a[i];



        for (size_t i=0; i<a.size(); ++i)
                std::cout<<(b[i])<<' ';

        return EXIT_SUCCESS;
}

gcc 8.3.1 and higher (and lower?) -O3

COLLECT_GCC=gcc-8
COLLECT_LTO_WRAPPER=/usr/lib64/gcc/x86_64-suse-linux/8/lto-wrapper
OFFLOAD_TARGET_NAMES=hsa:nvptx-none
Target: x86_64-suse-linux
Configured with: ../configure --prefix=/usr --infodir=/usr/share/info
--mandir=/usr/share/man --libdir=/usr/lib64 --libexecdir=/usr/lib64
--enable-languages=c,c++,objc,fortran,obj-c++,ada,go
--enable-offload-targets=hsa,nvptx-none=/usr/nvptx-none, --without-cuda-driver
--enable-checking=release --disable-werror
--with-gxx-include-dir=/usr/include/c++/8 --enable-ssp --disable-libssp
--disable-libvtv --disable-cet --disable-libcc1 --enable-plugin
--with-bugurl=http://bugs.opensuse.org/ --with-pkgversion='SUSE Linux'
--with-slibdir=/lib64 --with-system-zlib --enable-libstdcxx-allocator=new
--disable-libstdcxx-pch --enable-version-specific-runtime-libs
--with-gcc-major-version-only --enable-linker-build-id --enable-linux-futex
--enable-gnu-indirect-function --program-suffix=-8 --without-system-libunwind
--enable-multilib --with-arch-32=x86-64 --with-tune=generic
--build=x86_64-suse-linux --host=x86_64-suse-linux
Thread model: posix
gcc version 8.3.1 20190226 [gcc-8-branch revision 269204] (SUSE Linux)