re PR tree-optimization/37145 (XFAILs from PRE rewrite, SCCVN union optimization...

re PR tree-optimization/37145 (XFAILs from PRE rewrite, SCCVN union optimization disabled)

2008-09-22  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/37145
	* tree-ssa-sccvn.c (copy_reference_ops_from_ref): Re-enable
	value-numbering union accesses with their offset and size only.
	(visit_reference_op_load): Fix simplification of inserted conversions.
	* tree-ssa-pre.c (find_or_generate_expression): Do not
	recursively generate expressions if running FRE.

	* gcc.c-torture/compile/20080922-1.c: New testcase.
	* gcc.dg/tree-ssa/ssa-fre-7.c: Remove XFAIL.
	* gcc.dg/tree-ssa/ssa-fre-8.c: Likewise.
	* gcc.dg/tree-ssa/ssa-fre-9.c: Likewise.

From-SVN: r140562