Ping, plus minor rework (mostly non-functional changes)

gcc/ChangeLog:

2019-06-12  Joel Hutton  <Joel.Hutton@arm.com>

         * config/aarch64/aarch64-protos.h (aarch64_fpconst_pow2_recip): New prototype
         * config/aarch64/aarch64.c (aarch64_fpconst_pow2_recip): New function
         * config/aarch64/aarch64.md (*aarch64_<su_optab>cvtf<fcvt_target><GPF:mode>2_mult): New pattern
         (*aarch64_<su_optab>cvtf<fcvt_iesize><GPF:mode>2_mult): New pattern
         * config/aarch64/constraints.md (Dt): New constraint
         * config/aarch64/predicates.md (aarch64_fpconst_pow2_recip): New predicate

gcc/testsuite/ChangeLog:

2019-06-12  Joel Hutton  <Joel.Hutton@arm.com>

         * gcc.target/aarch64/fmul_scvtf_1.c: New test.

Bootstrapped and regression tested on aarch64-linux-none target.