* toplev.c (flag_sched2_use_superblocks, flag_sched2_use_traces):  New global variables.
	(lang_independent_options):  Add -fsched2-use-superblocks -fsced2-use-traces.
	(rest_of_compilation): Deal with it.
	* invoke.texi (-fsched2-use-traces, fsched2-use-superblocks):  Declare.
	* flags.h (flag_sched2_use_superblocks, flag_sched2_use_traces): Declare.
	* rtl.h (reg_to_stack):  Update prototype.
	* reg-stack.c (reg_to_stack): Return when something has changed;
	update liveness when executing after superblock scheduling.

	* combine.c (simplify_shift_const):  Simplify few special cases
	into constants.

From-SVN: r63183