RTEMS GNU Tools On-Line Library

Insn Attributes

Using and Porting the GNU Compiler Collection (GCC)

16.15: 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.

Using and Porting the GNU Compiler Collection (GCC)