Update clang to treat fp128 as a valid base type for homogeneous aggregate passing and returning.
Other than a few style nits that can be fixed on the commit, this LGTM.
// IEEE 754 binary128
This comment should probably be updated.
This expression looks very messy, I think it's probably better to rewrite it as multiple expressions or an if statement.
Is it still a homogeneous aggregate if it's nested?
And if so, should we add that to the test?