GCC 7 on ppc64le does not recognize vec_xl_be?

[Jeffrey Walton <noloader@xxxxxxxxx>]

Hi Everyone,

I have a Travis job failing on ppc64le:
https://travis-ci.org/noloader/cryptopp-pem/jobs/612654182 .

Compiling a source file with Power9 flags:

    g++ -DNDEBUG -g2 -O3 -mcpu=power9 -maltivec -c ppc_power9.cpp

That includes a header with this function:

    inline uint32x4_p VecLoadBE(const byte src[16])
    {
    #if defined(_ARCH_PWR9)
        return (uint32x4_p)vec_xl_be(0, CONST_V8_CAST(src));
    #elif (BIG_ENDIAN)
        return (uint32x4_p)VecLoad(src);
    #else
        return (uint32x4_p)VecReverse(VecLoad(src));
    #endif
}

Results in:

    ppc_simd.h: In function ‘uint32x4_p VecLoadBE(const byte*)’:
    ppc_simd.h:466:24: error: ‘vec_xl_be’ was not declared in this scope
         return (uint32x4_p)vec_xl_be(0, CONST_V8_CAST(src));

According to the GCC docs vec_xl_be is available with ISA 3.0:
https://gcc.gnu.org/onlinedocs/gcc/PowerPC-AltiVec-Built-in-Functions-Available-on-ISA-3_002e0.html

Does someone know why the compile is failing?

Thanks in advance.