[PATCH] Add a "no-split-stack" function attribute.

[Rafael Espíndola]

> Also, gcc supports a no_split_stack attribute in its split stack implementation.

I agree that it is a bit fuzzy. Strictly speaking you never know how
much stack space llvm will want for a function, but it is also very
local, so it is probably ok.

You probably want to disallow inlining into these functions, no? The
function itself might be carefully coded, but if it is calling into
code that expects to be able allocate more stack you will have
problems.

Cheers,
Rafael