[AArch64] Improve bit-test-branch pattern to avoid unnecessary register clobber

[AArch64] Improve bit-test-branch pattern to avoid unnecessary register clobber

2015-01-27  Ramana Radhakrishnan  <ramana.radhakrishnan@arm.com>
            Jiong Wang  <jiong.wang@arm.com>

  gcc/
    * config/aarch64/aarch64.md (tb<optab><mode>1): Clobber CC reg instead of
    scratch reg.
    (cb<optab><mode>1): Likewise.
    * config/aarch64/iterators.md (bcond): New define_code_attr.

  gcc/testsuite/
    * gcc.dg/long_branch.c: New testcase.

From-SVN: r220170