noreturn function attribute and ret asm instruction

[Zack Weinberg]

Richard Henderson <rth@redhat.com> writes:

> On Wed, Oct 01, 2003 at 12:00:22AM -0700, Zack Weinberg wrote:
>> It might be harder at the tree level; I'm not sure how noreturn is
>> being represented in tree-ssa.
>
> Only in the CFG.  If there's no edge to exit, then there's
> no flow to exit.  You'd have to find a way to represent the
> noreturn attribute in the ASM_EXPR so that it survives until
> the CFG is created.

In the original implementation of this, back in 2000
[http://gcc.gnu.org/ml/gcc-patches/2000-01/msg00190.html]
it was done by putting "pc" in the clobbers list, which should be
preserved fine; one would need to make the CFG creator aware of this
convention.

zw