Insn Attributes

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Instruction Attributes
======================

   In addition to describing the instruction supported by the target
machine, the `md' file also defines a group of "attributes" and a set of
values for each.  Every generated insn is assigned a value for each
attribute.  One possible attribute would be the effect that the insn
has on the machine's condition code.  This attribute can then be used
by `NOTICE_UPDATE_CC' to track the condition codes.

Defining Attributes: Specifying attributes and their values.
Expressions: Valid expressions for attribute values.
Tagging Insns: Assigning attribute values to insns.
Attr Example: An example of assigning attributes.
Insn Lengths: Computing the length of insns.
Constant Attributes: Defining attributes that are constant.
Delay Slots: Defining delay slots required for a machine.
Function Units: Specifying information for insn scheduling.

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