Teach VRP to register assertions along default switch labels (PR18046)

Teach VRP to register assertions along default switch labels (PR18046)

gcc/ChangeLog:

	PR tree-optimization/18046
	* genmodes.c (emit_mode_size_inline): Emit an assert that
	verifies that mode is a valid array index.
	(emit_mode_nuinits_inline): Likewise.
	(emit_mode_inner_inline): Likewise.
	(emit_mode_unit_size_inline): Likewise.
	(emit_mode_unit_precision_inline): Likewise.
	* tree-vrp.c: Include params.h.
	(find_switch_asserts): Register edge assertions for the default
	label which correspond to the anti-ranges of each case label.
	* params.def (PARAM_MAX_VRP_SWITCH_ASSERTIONS): New.
	* doc/invoke.texi: Document it.

gcc/testsuite/ChangeLog:

	PR tree-optimization/18046
	* gcc.dg/tree-ssa/ssa-dom-thread-6.c: Bump FSM count to 5.
	* gcc.dg/tree-ssa/vrp103.c: New test.
	* gcc.dg/tree-ssa/vrp104.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@238761 138bc75d-0d04-0410-961f-82ee72b054a4