Each procedure is represented by a doubly-linked list of instructions. These instructions contain references to the various types, symbols, and registers. Simple-SUIF instructions resemble assembly language instructions. Each one performs a relatively simple operation specified by its opcode.
Most instructions have several operands in registers.
This format provides a destination register and two source registers and is used for most of the opcodes. Not all of the registers are always used. The source register is only used with conditional branch instructions. See section Immediate Values . This format is only used for procedure call instructions.