gccint: Mode Iterators

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1 17.23.1 Mode Iterators
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1 Ports often need to define similar patterns for two or more different
1 modes.  For example:
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1    * If a processor has hardware support for both single and double
1      floating-point arithmetic, the 'SFmode' patterns tend to be very
1      similar to the 'DFmode' ones.
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1    * If a port uses 'SImode' pointers in one configuration and 'DImode'
1      pointers in another, it will usually have very similar 'SImode' and
1      'DImode' patterns for manipulating pointers.
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1  Mode iterators allow several patterns to be instantiated from one '.md'
1 file template.  They can be used with any type of rtx-based construct,
1 such as a 'define_insn', 'define_split', or 'define_peephole2'.
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· Defining Mode Iterators Defining a new mode iterator.
· Substitutions           Combining mode iterators with substitutions
· Examples                Examples
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