Are WAW and WAR hazards unique to RISC processors?

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Discussion Overview

The discussion centers on the presence of Write After Write (WAW) and Write After Read (WAR) hazards in RISC and CISC processor architectures. Participants explore whether these hazards are unique to RISC processors or if they can also occur in CISC designs, particularly in the context of pipeline processing.

Discussion Character

  • Debate/contested

Main Points Raised

  • Some participants question whether WAW and WAR hazards are exclusive to RISC processors, suggesting that CISC processors may also experience these hazards.
  • One participant asserts that any pipeline architecture capable of modifying data in multiple stages can encounter these hazards.
  • Another participant notes that discussions about hazards often reference RISC processors, but emphasizes that data hazards can occur in both CISC and RISC architectures.
  • A further contribution states that CPU hazards arise from pipeline processing in both CISC and RISC, and that without pipelining, WAW, WAR, and Read After Write (RAW) issues might still occur, but would be managed through software resource arbitration.

Areas of Agreement / Disagreement

Participants express differing views on whether WAW and WAR hazards are unique to RISC processors, indicating that multiple competing perspectives remain on this topic.

Contextual Notes

The discussion highlights the complexity of hazards in processor architectures and the role of pipelining, but does not resolve the nuances of definitions or the implications of these hazards across different architectures.

user366312
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TL;DR
Whenever I find something on hazard, I find it in the context of RISC processors like MIPS.
Are WAW and WAR hazards unique to RISC processors?

Or, CISCs can also encounter those hazards?
 
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You get this hazards with any pipeline architecture that can modify data in more than one stage.
 
user366312 said:
Summary: Whenever I find something on hazard, I find it in the context of RISC processors like MIPS.

Are WAW and WAR hazards unique to RISC processors?

Or, CISCs can also encounter those hazards?
In my experience a data hazard can be encountered on CISC as well as RISC processors.
 
CPU hazards are the result of pipeline processing - either CISC or RISC. If there is no pipe-lining, you might still run into WAW, WAR, and RAW issues, but they would be handled in the software as resource arbitration issues.
 

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