template<int version> REALM_FORCEINLINE bool sseavx()
{
/*
Return wether or not SSE 3.0 (if version = 30) or 4.2 (for version = 42) is supported. Return value
is based on the CPUID instruction.
sse_support = -1: No SSE support
sse_support = 0: SSE3
sse_support = 1: SSE42
avx_support = -1: No AVX support
avx_support = 0: AVX1 supported
sse_support = 1: AVX2 supported (not yet implemented for detection in our cpuid_init(), todo)
This lets us test very rapidly at runtime because we just need 1 compare instruction (with 0) to test both for
SSE 3 and 4.2 by caller (compiler optimizes if calls are concecutive), and can decide branch with ja/jl/je because
sse_support is signed type. Also, 0 requires no immediate operand. Same for AVX.
We runtime-initialize sse_support in a constructor of a static variable which is not guaranteed to be called
prior to cpu_sse(). So we compile-time initialize sse_support to -2 as fallback.
*/
REALM_STATIC_ASSERT(version == 1 || version == 2 || version == 30 || version == 42, "Only version == 1 (AVX), 2 (AVX2), 30 (SSE 3) and 42 (SSE 4.2) are supported for detection");
#ifdef REALM_COMPILER_SSE
if (version == 30)
return (sse_support >= 0);
else if (version == 42)
return (sse_support > 0); // faster than == 1 (0 requres no immediate operand)
else if (version == 1) // avx
return (avx_support >= 0);
else if (version == 2) // avx2
return (avx_support > 0);
#else
return false;
#endif
}
// to_str() is used by the integer index. The existing StringIndex is re-used for this
// by making Column convert its integers to strings by calling to_str().
template <class T> inline StringData to_str(const T& value)
{
REALM_STATIC_ASSERT((std::is_same<T, int64_t>::value), "");
const char* c = reinterpret_cast<const char*>(&value);
return StringData(c, sizeof(T));
}