re PR target/51244 ([SH] Inefficient conditional branch and code around T bit)

re PR target/51244 ([SH] Inefficient conditional branch and code around T bit)

	PR target/51244
	* config/sh/sh_treg_combine.cc: New SH specific RTL pass.
	* config.gcc (SH extra_objs): Add sh_ifcvt.o.
	* config/sh/t-sh (sh_treg_combine.o): New entry.
	* config/sh/sh.c (sh_fixed_condition_code_regs): New function that
	implements the target hook TARGET_FIXED_CONDITION_CODE_REGS.
	(register_sh_passes): New function.  Register sh_treg_combine pass.
	(sh_option_override): Invoke it.
	(sh_canonicalize_comparison): Handle op0_preserve_value.
	* sh.md (*cbranch_t"): Do not try to optimize missed test and branch
	opportunities.  Canonicalize branch condition.
	(nott): Allow only if pseudos can be created for non-SH2A.

	PR target/51244
	* gcc.dg/torture/p51244-21.c: New.
	* gcc.target/sh/pr51244-20.c: New.
	* gcc.target/sh/pr51244-20-sh2a.c: New.

From-SVN: r203492