[PATCH] Fix PR tree-optimization/32589

[Eric Botcazou]

Hi,

This is the Ada bootstrap failure on 32-bit platforms, see
  http://gcc.gnu.org/ml/gcc/2007-07/msg00070.html

To recap, FRE may create non-GIMPLE expressions that are nevertheless accepted 
by the predicates in tree-gimple.c, so they cannot be re-gimplified later by 
the existing mechanisms.

As suggested by Diego, a first approach would be to create is_gimple_const and 
use it instead of is_gimple_[min_]invariant when it makes sense to do so.  
The problem, as I found out when trying to implement it, is the last part of 
the previous sentence: IMHO it is not clear at all when is_gimple_const 
should be used instead of is_gimple_[min_]invariant in the tree optimizers.
I don't have the big picture here so I cannot really formulate anything.

The second approach is described in passes.c:

  /* Note that the folders should only create gimple expressions.
     This is a hack until the new folder is ready.  */
  in_gimple_form = (cfun && (cfun->curr_properties & PROP_trees)) != 0;

and is of course much more straightforward, hence the proposed patch.

Bootstrapped/regtested on i586-suse-linux, but the Ada library cannot be built 
because of another problem in tree-ssa-sccvn.c (PR tree-opt/32713).

OK for mainline?


2007-07-10  Eric Botcazou  <ebotcazou@adacore.com>

	PR tree-optimization/32589
	* Makefile.in (fold-const.o): Add dependency on TREE_GIMPLE_H.
	* fold-const.c: Include tree-gimple.h.
	(try_move_mult_to_index): If in GIMPLE form, do not synthesize
	non-GIMPLE index.
	* tree-gimple.c (is_gimple_min_invariant): Clarify head comment.
	* doc/tree-ssa.texi (Rough GIMPLE Grammar): Add missing rule.


-- 
Eric Botcazou
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