tree-vn.c (expressions_equal_p): Do not check type equality or compatibility before calling operand_equal_p.

2008-04-17  Richard Guenther  <rguenther@suse.de>

	* tree-vn.c (expressions_equal_p): Do not check type
	equality or compatibility before calling operand_equal_p.
	* fold-const.c (operand_equal_p): Check equivalence of
	integer constants before bailing out due to signedness or
	precision differences.
	* tree-ssa-sccvn.c (copy_reference_ops_from_ref): Ignore
	spurious differences in type qualification.  Ignore types
	for COMPONENT_REFs at all.

	* gcc.dg/tree-ssa/ssa-fre-17.c: New testcase.

From-SVN: r134384