Hi Seongbae This would reduce the stack memory, but I'd lose the advantage of all of those register windows. I'd like to still have the fast register windows, and if I could avoid the mflat the callee wouldn't need to save all those registers and consume stack space for this.
David -----Original Message----- From: Seongbae Park 박성배 朴成培 [mailto:seongbae.p...@gmail.com] Sent: Monday, December 15, 2008 2:40 PM To: David Meggy Cc: gcc@gcc.gnu.org Subject: Re: reducing stack size by breaking SPARC ABI for OS-less environments On Mon, Dec 15, 2008 at 2:20 PM, David Meggy <david.me...@icron.com> wrote: > Hi, I'm working on a very embedded project where we have no operating > system, and there is no window overflow trap handler. I'm really > stretched for memory and I'd like to reduce the stack size. I haven't > not being able to find anyone else who is looking at reducing the stack > usage by google searching, but it seems like there is room to be saved, > and I need the extra space. > > As I have no window overflow trap handler the space reserved on the > stack for saving in and local registers is just wasted memory. Is there > any way I can reclaim this space by forcing the compiler to not honour > the standard SPARC ABI? > > Would it be possible to take this one step further and drop the stack > space for arguments? We don't have functions with large numbers of > arguments, so all arguments should be passed in registers. > > Although only a single word, the One-word hidden parameter, seems like a > waste if none of our code ever uses it. > > David With gcc 3.x, you can use -mflat which would do what you want. gcc 4.x completely dropped the support for -mflat, so unless you (or someone) work on reintroducing it, IHMO, you're out of luck with gcc 4.x. Seongbae
