1.5 Program Order and Dependencies

Execution Order and Stalling


The actual execution order depends on the processor's organization; in a typical pipelined processor, instructions are executed only in program order. That is, the next sequential instruction may begin execution during the next cycle, if all of its operands are valid. Otherwise, the pipeline stalls until the operands do become valid.

Since instructions execute in order, stalls usually delay all subsequent instructions.

A clever compiler can improve performance by re-arranging instructions to reduce the frequency of these stall cycles.




Copyright 1995, MIPS Technologies, Inc. -- 29 JAN 96


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