i386: Unify {general,timode}_scalar_chain::convert_op [PR111822]

i386: Unify {general,timode}_scalar_chain::convert_op [PR111822]

Recent PR111822 fix implemented REG_EH_REGION note copying to a STV converted
preload instruction in general_scalar_chain::convert_op.  However, the same
issue remains in timode_scalar_chain::convert_op.  Instead of copying the
newly introduced code to timode_scalar_chain::convert_op, the patch unifies
both functions to a common function.

	PR target/111822

gcc/ChangeLog:

	* config/i386/i386-features.cc (smode_convert_cst): New function
	to handle SImode, DImode and TImode immediates, generalized from
	timode_convert_cst.
	(timode_convert_cst): Remove.
	(scalar_chain::convert_op): Unify from
	general_scalar_chain::convert_op and timode_scalar_chain::convert_op.
	(general_scalar_chain::convert_op): Remove.
	(timode_scalar_chain::convert_op): Remove.
	(timode_scalar_chain::convert_insn): Update the call to
	renamed timode_convert_cst.
	* config/i386/i386-features.h (class scalar_chain):
	Redeclare convert_op as protected class member.
	(class general_calar_chain): Remove convert_op.
	(class timode_scalar_chain): Ditto.

gcc/testsuite/ChangeLog:

	* g++.target/i386/pr111822.C (dg-do): Compile only for ia32 targets.
	(dg-options): Add -march=x86-64.