http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57908
--- Comment #4 from Yann Droneaud <yann at droneaud dot fr> --- (In reply to Andrew Pinski from comment #2) > Your test program is not fully testing things correctly. > kind name address size alignment required > > object | u8_5 | 0x7fffefdd4810 | 3 | 16 | 1 > > object | u8_6 | 0x7fffefdd4800 | 2 | 2048 | 1 > > object | u8_7 | 0x7fffefdd47ff | 1 | 1 | 1 > > Shows why. There are two variables right next to each other but the > alignment recorded is 2048 but that was just accidental. The alignment of > u8_6 is 16 due to the next variable at 10. Have you noticed that u8_7 is an array of 1 element only ? Array of 1 element (bytes) only are not aligned on 16 bytes boundary. Array of 2 bytes and greater get aligned on 16 bytes boundary. Should I show another test case ?
