https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79518
--- Comment #4 from Evan Nemerson <e...@coeus-group.com> --- I agree that GCC's implementation makes more sense, but unfortunately it makes it hard to write portable code. I'm not suggesting the current behavior be abandoned, only that __builtin_assume_aligned be enhanced so the argument is marked as aligned when possible. Think of it as an optimization opportunity; given something like void* foo = __builtin_assume_aligned(bar, 16); /* Use bar for something instead of foo */ GCC could see that bar is 16-byte aligned and generate better code accordingly, even though the programmer did something dumb. I won't reopen this, but I hope you will… AFAICT there aren't any disadvantages, and it would be very helpful for people with code already optimized using MSVC, ICC, etc.
