[AArch64] Fix some define_insn_and_split conditions

[AArch64] Fix some define_insn_and_split conditions

The split conditions for aarch64_simd_bsldi_internal and
aarch64_simd_bsldi_alt were:

  "&& GP_REGNUM_P (REGNO (operands[0]))"

But since they (deliberately) can be split before reload, the operand
matched by register_operand can be a SUBREG rather than a REG.  This
triggered a boostrap failure building libgcc with rtl checking enabled.

While checking other define_insn_and_splits for the same thing,
I noticed a couple of SIMD ones were missing the leading "&&",
meaning that they would trigger even without TARGET_SIMD.  That
shouldn't matter in practice, since combine should never end up
generating matching rtl, but...

2017-12-05  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
	* config/aarch64/aarch64-simd.md (aarch64_simd_bsldi_internal)
	(aarch64_simd_bsldi_alt): Check REG_P before GP_REGNUM_P.
	(aarch64_cm<optab>di, aarch64_cmtstdi): Add leading "&&" to
	split condition.

From-SVN: r255423