re PR rtl-optimization/83628 (performance regression when accessing arrays on alpha)

re PR rtl-optimization/83628 (performance regression when accessing arrays on alpha)

	PR target/83628
	* config/alpha/alpha.md (*sadd<modesuffix>): Use ASHIFT
	instead of MULT rtx.  Update all corresponding splitters.
	(*saddl_se): Ditto.
	(*ssub<modesuffix>): Ditto.
	(*ssubl_se): Ditto.
	(*cmp_sadd_di): Update split patterns.
	(*cmp_sadd_si): Ditto.
	(*cmp_sadd_sidi): Ditto.
	(*cmp_ssub_di): Ditto.
	(*cmp_ssub_si): Ditto.
	(*cmp_ssub_sidi): Ditto.
	* config/alpha/predicates.md (const23_operand): New predicate.
	* config/alpha/alpha.c (alpha_rtx_costs) [PLUS, MINUS]:
	Look for ASHIFT, not MULT inner operand.
	(alpha_split_conditional_move): Update for *sadd<modesuffix> change.

testsuite/ChangeLog:

	PR target/83628
	* gcc.target/alpha/pr83628-1.c: New test.
	* gcc.target/alpha/pr83628-2.c: Ditto.

From-SVN: r256228