Re: [PATCH][MIPS] mwarn-framesize= option

[David Daney <ddaney at avtrex dot com>]

Mark Mitchell wrote:
> Andreas Krebbel wrote:
> > Hello,
> >
> > > > Here is patch to add -mwarn-framesize=<size> option to MIPS. 
>
> > > There is a generic implementation of this already on the trunk as
> > > -Wframe-larger-than=N.
>
> > The generic option does not necessarily do the same thing.
>
> Right; in fact, the -Wframe-larger docs say:
>
> > The computation done to determine the stack frame size is approximate
> > and not conservative.
> > The actual requirements may be somewhat greater than @var{len}
> > even if you do not get a warning.  In addition, any space allocated
> > via @code{alloca}, variable-length arrays, or related constructs
> > is not included by the compiler when determining
> > whether or not to issue a warning.
>
> So, I do think Maxim's patch is a good thing.  (I'm not approving it 
> though; I'm expecting that a MIPS backend maintainer will probably 
> comment on it soon.)
>
> Perhaps it would be a nice (orthogonal) improvement if 
> -Wframe-larger-than used the back-end specific code, though.  We could 
> have a target hook to compute the frame size, using the generic code in 
> get_framesize as a fallback guess.  Then, the user interface would 
> always be -Wframe-larger-than which would work on all targets -- it's 
> just that on some the answers would be more accurate than others.

FWIW, I agree that this is the way to go.

Since we are in stage 1, this would be the time to get this in.  We 
would then not have two different ways to specify very nearly the same 
thing.  It would also save us the trouble of deprecating and removing a 
mips specific version in the future.

David Daney