[AArch64] Catch attempts to use SVE types when SVE is disabled

[AArch64] Catch attempts to use SVE types when SVE is disabled

This patch reports an error if code tries to use variable-length
SVE types when SVE is disabled.  We already report a similar error
for definitions or uses of SVE functions when SVE is disabled.

2019-12-02  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* config/aarch64/aarch64.c (aarch64_report_sve_required): New function.
	(aarch64_expand_mov_immediate): Use it when attempting to measure
	the length of an SVE vector.
	(aarch64_mov_operand_p): Only allow SVE CNT immediates when
	SVE is enabled.

gcc/testsuite/
	* gcc.target/aarch64/sve/acle/general/nosve_4.c: New test.
	* gcc.target/aarch64/sve/acle/general/nosve_5.c: Likewise.
	* gcc.target/aarch64/sve/pcs/nosve_4.c: Expected a second error
	for the copy.
	* gcc.target/aarch64/sve/pcs/nosve_5.c: Likewise.
	* gcc.target/aarch64/sve/pcs/nosve_6.c: Likewise.

From-SVN: r278909