On Mon, Jan 16, 2012 at 10:41 AM, Bakul Shah <bakul@bitblocks.com> wrote:

A frame pointer is needed for C99's variable length arrays but not otherwise. Only an issue if ever plan9 C is extended to handle C99 or C1x. gcc has to do the right thing even with -fno-frame-pointer.

What we do in problematic cases with Comeau is to generate code to arrange for the allocation of the VLA on the heap.  I'm not saying this is perfect, but at least it gets the feature implementable and up and running as "a portable implementation" versus perhaps not being able to implement it at all on some platforms.