re PR target/53988 ([SH] tst Rm,Rn not used for QI/HImode)

gcc/
	PR target/53988
	* config/sh/sh-protos.h (sh_find_set_of_reg): Add option to ignore
	reg-reg copies.
	(sh_extending_set_of_reg): New struct.
	(sh_find_extending_set_of_reg, sh_split_tst_subregs,
	sh_remove_reg_dead_or_unused_notes): New Declarations.
	* config/sh/sh.c (sh_remove_reg_dead_or_unused_notes,
	sh_find_extending_set_of_reg, sh_split_tst_subregs,
	sh_extending_set_of_reg::use_as_extended_reg): New functions.
	* config/sh/sh.md (*tst<mode>_t_zero): Rename to *tst<mode>_t_subregs,
	convert to insn_and_split and use new function sh_split_tst_subregs.

gcc/testsuite/
	PR target/53988
	* gcc.target/sh/pr53988-1.c: New.

From-SVN: r219623