Am I doing something wrong or is this a bug in gcc? The problem is in 47942806932686753431 part, not in __uint128_t p. According to gcc docs there’s no way to declare 128 bit constant: There is no support in GCC for expressing an integer constant of type __int128 for targets with long long integer less … Read more
For GCC before C23, a primitive 128-bit integer type is only ever available on 64-bit targets, so you need to check for availability even if you have already detected a recent GCC version. In theory gcc could support TImode integers on machines where it would take 4x 32-bit registers to hold one, but I don’t … Read more
I typically see a 30% speed improvement for compute-intensive code on x86-64 compared to x86. This is most likely due to the fact that we have 16 x 64 bit general purpose registers and 16 x SSE registers instead of 8 x 32 bit general purpose registers and 8 x SSE registers. This is with … Read more