Re: ARM: Invalid Stack Alignment BUG

[Richard Earnshaw <rearnsha at arm dot com>]

> On Wed, Mar 15, 2000 at 09:42:48AM -0700, Jeffrey A Law wrote:
> >   > IMO this must be handled in a 
> >   > machine independent manner, based on the information already supplied.
> > Agreed,  if we are losing space due to inconvenient rounding, then we should
> > find a describe when rounding should occur so that we can write the code
> > once in the generic parts of the compiler rather than over and over again
> > in every backend.
> 
> "Over and over"?  One line for an alignment?

in at least three different places in every backend: 
INITIAL_ELIMINATION_OFFSET, gen_prologue, gen_epilogue (or equivalent 
alternatives).  It's not even the same functions in each backend.

> 
> The only way to do the rounding correctly not in the back end
> is to do the entire frame layout not in the back end.  Rounding
> just the size of the local variable store is _always_ not the
> right thing to do.  Ideally you want to round the size of the
> entire frame -- locals, save regs, outgoing args, varargs spill
> and everything.

But it still seems nonsensical to tell MI part of the compiler that I need 
an aligned stack frame and to then have to align the stack frame myself.  
How do I know that by adjusting the frame size I'm not breaking 
assumptions built into the generated rtl?

Maybe its just a matter of creating get_rounded_frame_size() and telling 
backend writers to use that (rather than get_frame_size()).  But this 
would still be a cleaner abstraction than the current mess.

R.