Computers as Components, 2nd Edition

254 CHAPTER 5 Program Design and Analysis

basic multiply and add operations are fast, some transcendental functions can

take thousands of cycles to execute.

■ Execution times of instructions are not independent. The execution time

of one instruction depends on the instructions around it. For example, many

CPUs use register bypassing to speed up instr uction sequences when the result

of one instruction is used in the next instruction. As a result, the execution

time of an instruction may depend on whether its destination register is used

as a source for the next operation (or vice versa).

■ The execution time of an instruction may depend on operand