[Patch, Fortran] PR fortran/44709: Clean up local variables with try-finally

[Daniel Kraft]

Hi all,

the attached patch does what I wrote about in 
http://gcc.gnu.org/ml/fortran/2010-07/msg00058.html.  Briefly, I 
modified gfc_trans_deferred_vars and its callees such that init and 
cleanup code (like memory allocation / deallocation) is collected 
seperately rather than wrapped around the function body directly; this 
is then used to do the clean-up with a try-finally middle-end 
expression, so that all exits safely do the cleanup automagically. 
Which fixes the wrong-code / memory-leak part of PR 44709.

Currently, multiple returns from procedures are handled via a jump to a 
label at the end of the function, from which on the cleanup was done 
before (in order to work around the problem in the PR for BLOCKs).  I 
think that this may no longer be needed in fact now (am I right?  Or is 
there another reason why we want only a single exit point from all 
procedures?).  I'll work on a second patch to remove this (if it works 
out) as follow-up.  Hopefully this can help the middle-end a little bit 
and make the code-structure clearer to it.

Most of the attached patch are more or less mechanical changes (except 
the code directly working with gfc_wrapped_block); I used to introduce a 
mistake there (which was fortunately caught by a lot of regressions), 
but please take a careful look at all those.

No regressions on GNU/Linux-x86-32, and additionally valgrind shows no 
longer any memory leaks for code like that in the PR (and the tree-dump 
also looks fine).  This was with SVN trunk some days ago, though, so I'm 
at the moment building and testing with a fresh update.

Ok for trunk if no failures with that, either?

Yours,
Daniel

-- 
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