Arm: Fix NEON REG to REG reload failures. (PR/target 88850)

Arm: Fix NEON REG to REG reload failures. (PR/target 88850)

We currently return cost 2 for NEON REG to REG moves, which would be incorrect
for 64 bit moves.  We currently don't have a pattern for this in the neon_move
alternatives because this is a bit of a special case.  We would almost never
want it to use this r -> r pattern unless it really has no choice.

As such we add a new neon r -> r move pattern but also hide it from being used
to determine register preferences and also disparage it during LRA.

gcc/ChangeLog:

	PR/target 88850
	* config/arm/neon.md (*neon_mov<mode>): Add r -> r case.

gcc/testsuite/ChangeLog:

	PR/target 88850
	* gcc.target/arm/pr88850.c: New test.

From-SVN: r268612