Destrictiveness of expansion and tree inlining deadlock?

Destrictiveness of expansion and tree inlining deadlock?

[Jan Hubicka]

Hi,
I am looking into the reason why enabling unit-at-a-time for bootstrap
causes failure on some architectures.  Apparently it is because I now
emit functions in topological order, so function that is inline and
global is always fir expanded and later inlined.  Expansion is (to my
understanding) destructive and makes later inlining impossible.

I believe that current code gets it wrong as well as it does:
  /* Generate the RTL for this function.  */
  expand_stmt (DECL_SAVED_TREE (fndecl));
  if (uninlinable)
    {
      /* Allow the body of the function to be garbage
	 collected.  */
      DECL_SAVED_TREE (fndecl) = NULL_TREE;
    }

To my understanding it works better just because inline functions are
deffered so they usually appear after the callers in the sequence.
Still they may be inlined into the inline functions expanded later.

Replacing it with unconditional clear would ineed fix the problem I am
seeing but this breaks always_inline attribute as we would miss inlining
oppurtunities.  Any hint where to go from here?

Honza

Re: Destrictiveness of expansion and tree inlining deadlock?

[Mark Mitchell]

--On Saturday, February 22, 2003 11:20:31 AM +0100 Jan Hubicka <jh@suse.cz> 
wrote:

>  Expansion is (to my
> understanding) destructive and makes later inlining impossible.

That should not be the case.  It was the case with the RTL inliner, but it 
should not be the case with the tree inliner.

-- 
Mark Mitchell                mark@codesourcery.com
CodeSourcery, LLC            http://www.codesourcery.com

Re: Destrictiveness of expansion and tree inlining deadlock?

[Jan Hubicka]

> 
> 
> --On Saturday, February 22, 2003 11:20:31 AM +0100 Jan Hubicka <jh@suse.cz> 
> wrote:
> 
> > Expansion is (to my
> >understanding) destructive and makes later inlining impossible.
> 
> That should not be the case.  It was the case with the RTL inliner, but it 
> should not be the case with the tree inliner.

Hmm, my topological sort in unit-at-a-time manages to assemble most of
inline functions before they are inlined and I am hitting one crash in:
  else if (TREE_CODE (*tp) == UNSAVE_EXPR)
    /* UNSAVE_EXPRs should not be generated until expansion time.  */
    abort ();
This made me believe that expansion creates those trees and thus is
destructive.  In the case this is wrong, what happens here?

Honza
> 
> -- 
> Mark Mitchell                mark@codesourcery.com
> CodeSourcery, LLC            http://www.codesourcery.com