Catch-22: LIR won't lift

Bugzilla Link	1022
Created on	Sep 11, 2012 22:32
Version	svn
OS	Linux
Architecture	PC

Extended Description

I just traced an AWLF failure partway back to this loopfun code:
int  loopfun( int _lacs_2325) {
...
 _uprf_1573, _uprf_1574 = _non_neg_val_S_( _lacs_2325);
  loopfun( _uprf_1573);
There are two distinct problems here:
a. LACS won't propagate AVIS_MINVAL( _lacs_2325) = 0 into the loopfun,
   because the variable is not loop-invariant.
b. DLIR won't lift the guard expression out of the loopfun, for the 
   same reason, I think.
As I write this, I realize that, in this particular case, I may
be able to resolve the issue this enhancement to LACS:
In the calling environment, _lacs_2325 has AVIS_MINVAL = 0;
In the recursive call, _uprf_1573 has AVIS_MINVAL = 0.
In that case, LACS can happily set AVIS_MINVAL( _lacs_2325) = 0,
and the code should get better.
However, I suspect this is not the case in general, so welcome
ideas on better ways to tackle this problem.
sac2c -V
sac2c v1.00-beta (Haggis And Apple)
 developer rev 18218:MODIFIED linux-gnu_x86_64
 (Tue Sep 11 16:07:19 EDT 2012 by sac)
cd ~/sac/testsuite/optimizations/lacs$ 
sac2c simpleLoopAKD.sac -bopt:saacyc:lof:5 -doawlf -nowlf  -v1 -#d,LIR,WLIR,DLIR &> crud