* Makefile.in (tree-chrec.o): Depends on SCEV_H.
	* tree-chrec.c: Include tree-scalar-evolution.h.
	(chrec_convert): Instantiate the base and step before calling
	scev_probably_wraps_p that would fail on parametric evolutions.
	Collect all the fails into a single section failed_to_convert,
	print a diagnostic, and return chrec_dont_know instead of calling
	fold_convert.
	* tree-scalar-evolution.c (loop_closed_phi_def): New.
	(instantiate_parameters_1): Avoid instantiation of loop closed ssa
	phi nodes.
	(scev_const_prop): Don't replace the definition of a loop closed ssa
	phi node by itself, or by another loop closed ssa phi node.
	* tree-ssa-loop-niter.c (scev_probably_wraps_p, convert_step): Check
	that base and step are defined.

From-SVN: r104092