https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94338
--- Comment #7 from huaixin chang <huaixin....@alibaba-inc.com> --- (In reply to Martin Sebor from comment #4) > Sounds like there's agreement that the code should at least get a warning > then, so confirmed. > > The attribute aligned section of the manual describing the variable > attribute says: > > When used on a struct, or struct member, the aligned attribute can only > increase the alignment... > > It's not clear whether struct here refers to a type or a variable (I'm > guessing it's former but it's in the Common Variable Attribute section so it > could easily be read as the latter). Either way, reducing the alignment of > an object whose members explicitly ask for stricter alignment seems like a > dangerous thing to do without a warning. > > I'll see if I can do this for GCC 11. It seems that the compiler thinks A.a is already aligned to 128-byte. Because as I print alignof(A.a) and alignof(A.b) with the same definition, they are 128. $./align address of A 0x42003c alignof A 4 address of A.a 0x42003c alignof A.a 128 address of A.b 0x4200bc alignof A.b 128 Is it in your consideration to actually align A.a to 128-byte boundary?
