Why complicate this with SSE checks? ...
I mean I do agree with you, but maybe we should bring this up to GCC devs? Not much we can do over here.
MinGW just assumes 16-bit alignment. I don't know why they made that decision. It does create problems with callbacks in MinGW compiled code, or using a MinGW compiled dll from MSVC. All this is actually well documented, and dates back at least 10 years.
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I think conversation in this thread has drifted quite a bit. What do you suggest I do here, @insn? We can use `incoming/preferred-stack-boundary`, or make sure our stack is aligned to 16 bytes (why is it not, btw?). But I don't think those are relevant to this MR.