Michael Veksler <mveksler@xxxxxxxxxxxxxxxxx> writes: > I wanted to check how many bits long double takes. So I checked > sizeof(long double) which, naturally, may account for padding. On > x86-64 it takes 16 bytes and only 12 on x86, a difference of 4 > bytes. This supported my hope that on x86-64 we would have "long > double"= |__float128|. Alas, no. On x86_64 long double is an 80-bit floating point number, just as on 32-bit x86. The size is 16 bytes because the x86_64 prefers to align large values to 8-byte boundaries. gcc works this way because the 80-bit floating point format is supported directly in hardware, unlike the 128-bit format. Ian
