[ARM][PR82989] Fix unexpected use of NEON instructions for shifts

[ARM][PR82989] Fix unexpected use of NEON instructions for shifts

This patch fixes PR82989 so that we avoid NEON instructions when
-mneon-for-64bits is not enabled. This is more of a short term fix
for the real deeper problem of making an early decision of choosing
or rejecting NEON instructions. There is now a new ticket PR84467 to
deal with the longer term solution.
(Please refer to the discussion in the bug report for more details).

Sudi

*** gcc/ChangeLog ***

2018-03-20  Sudakshina Das  <sudi.das@arm.com>

	PR target/82989
	* config/arm/neon.md (ashldi3_neon): Update ?s for constraints
	to favor GPR over NEON registers.
	(<shift>di3_neon): Likewise.

*** gcc/testsuite/ChangeLog ***

2018-03-20  Sudakshina Das  <sudi.das@arm.com>

	PR target/82989
	* gcc.target/arm/pr82989.c: New test.

From-SVN: r258677