Add tunning of ldpw for THunderX.

Add tunning of ldpw for THunderX.

2016-09-12  Andrew Pinski  <apinski@cavium.com>

        * config/aarch64/aarch64-tuning-flags.def (SLOW_UNALIGNED_LDPW):
        New tuning option.
        * config/aarch64/aarch64.c (thunderx_tunings): Enable
        AARCH64_EXTRA_TUNE_SLOW_UNALIGNED_LDPW.
        (aarch64_operands_ok_for_ldpstp): Return false if
        AARCH64_EXTRA_TUNE_SLOW_UNALIGNED_LDPW and the mode
        was SImode and the alignment is less than 8 byte.
        (aarch64_operands_adjust_ok_for_ldpstp): Likewise.
2016-09-12  Andrew Pinski  <apinski@cavium.com>

        * gcc.target/aarch64/thunderxloadpair.c: New testcase.
        * gcc.target/aarch64/thunderxnoloadpair.c: New testcase.

From-SVN: r240102