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   2   Copyright 1988-2022 Free Software Foundation, Inc.
   3   This is part of the GCC manual.
   4   For copying conditions, see the copyright.rst file.
   5
   6 .. _nios-ii-function-attributes:
   7
   8 Nios II Function Attributes
   9 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  10
  11 These function attributes are supported by the Nios II back end:
  12
  13 .. index:: target function attribute
  14
  15 .. nios-ii-fn-attr:: target (options)
  16
  17   As discussed in :ref:`common-function-attributes`, this attribute
  18   allows specification of target-specific compilation options.
  19
  20   When compiling for Nios II, the following options are allowed:
  21
  22   :samp:`custom-{insn}={N}` :samp:`no-custom-{insn}`
  23
  24     .. index:: target("custom-insn=N") function attribute, Nios II, target("no-custom-insn") function attribute, Nios II
  25
  26     Each :samp:`custom-{insn}={N}` attribute locally enables use of a
  27     custom instruction with encoding :samp:`{N}` when generating code that uses
  28     :samp:`{insn}`.  Similarly, :samp:`no-custom-{insn}` locally inhibits use of
  29     the custom instruction :samp:`{insn}`.
  30     These target attributes correspond to the
  31     :option:`-mcustom-insn=N` and :option:`-mno-custom-insn`
  32     command-line options, and support the same set of :samp:`{insn}` keywords.
  33     See :ref:`nios-ii-options`, for more information.
  34
  35   :samp:`custom-fpu-cfg={name}`
  36
  37     .. index:: target("custom-fpu-cfg=name") function attribute, Nios II
  38
  39     This attribute corresponds to the :option:`-mcustom-fpu-cfg=name`
  40     command-line option, to select a predefined set of custom instructions
  41     named :samp:`{name}`.
  42     See :ref:`nios-ii-options`, for more information.