Hello!

Attached patch optimizes ix86_atomic_assign_expand_fenv by using
register form of "fnstsw %ax" instead of "fnstsw <mem>". This way a
memory RW cycle is removed for a temporary.

2014-07-12  Uros Bizjak  <ubizjak@gmail.com>

    * config/i386/i386-builtin-types.def: Add USHORT_FTYPE_VOID.
    Remove VOID_FTYPE_PUSHORT.
    * config/i386/i386.c (bdesc_special_args) <__builtin_ia32_fnstsw>:
    Change code to USHORT_FTYPE_VOID.
    (ix86_expand_special_args_builtin): Handle USHORT_FTYPE_VOID.
    (ix86_expand_builtin): Remove IX86_BUILTIN_FNSTSW handling.
    (ix86_atomic_assign_expand_fenv): Update for
    __builtin_ia32_fnstsw changes.
    * config/i386/i386.md (x86_fnstsw_1): Set length unconditionally to 2.
    (fnstsw): Change operand 0 to nonimmediate operand.

Bootstrapped and regression tested on x86_64-linux-gnu {,-m32} and
committed to mainline SVN.

Uros.