MSP430: Tweaks to generation of 430X instructions

MSP430: Tweaks to generation of 430X instructions

gcc/ChangeLog:

2019-10-24  Jozef Lawrynowicz  <jozef.l@mittosystems.com>

	* config/msp430/constraints.md: Allow post_inc for "Ya" constraint.
	* config/msp430/msp430.md (430x_shift_left): Use RLAM when the constant
	shift amount is between 1 and 4.
	(430x_arithmetic_shift_right): Use RRAM when the constant shift amount
	is between 1 and 4.

gcc/testsuite/ChangeLog:

2019-10-24  Jozef Lawrynowicz  <jozef.l@mittosystems.com>

	* gcc.target/msp430/emulate-slli.c: Skip for -mcpu=msp430.
	Add shift by a constant 5 bits.
	Update scan-assembler directives.
	* gcc.target/msp430/emulate-srai.c: Likewise.
	* gcc.target/msp430/emulate-srli.c: Skip for -mcpu=msp430.

From-SVN: r277394