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Re: What do do with the exceptional case of expand_case for SJLJ exceptions

From: Jan Hubicka <hubicka at ucw dot cz>
To: Richard Guenther <richard dot guenther at gmail dot com>
Cc: Steven Bosscher <stevenb dot gcc at gmail dot com>, GCC Mailing List <gcc at gcc dot gnu dot org>, Richard Henderson <rth at redhat dot com>
Date: Wed, 18 Apr 2012 12:39:28 +0200
Subject: Re: What do do with the exceptional case of expand_case for SJLJ exceptions
References: <CABu31nMg0zBJCN2-jSfM_C8SOnPoOJyGBvJqu_=B=a53eOD0-g@mail.gmail.com> <CAFiYyc1g2h_CtkWQYLtU=+RCz26XWH5VLTmELG0hgxoVzaWEqw@mail.gmail.com>

> > What is the reason why lowering for SJLJ exceptions is not done in GIMPLE?
> 
> Because it completely wrecks loops because we factor the SJLJ site,
> thus
> 
> fn ()
> {
> ...
>   for (;;)
>     {
>        try { X } catch { Y }
>     }
> 
> becomes
> 
> fn ()
> {
>    if (setjmp ())
>      {
>         switch (...)
>            ... goto L;
>      }
>    for (;;)
>      {
>         X;
>         L:
>           Y;
>      }

Well, if SJLJ lowering happens as gimple pass somewhere near the end of gimple
queue, this should not be problem at all. (and implementation would be cleaner)

Honza

Follow-Ups:
- Re: What do do with the exceptional case of expand_case for SJLJ exceptions
  - From: Richard Henderson

References:
- What do do with the exceptional case of expand_case for SJLJ exceptions
  - From: Steven Bosscher
- Re: What do do with the exceptional case of expand_case for SJLJ exceptions
  - From: Richard Guenther

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