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Eric Rotenberg

A Study of Control Independence Page 1 A Study of Control Independence Eric Rotenberg Page 2 Slide 2 •High instruction-level parallelism (ILP) - requires large instruction scheduling window - branches make this difficult •Branches introduce control dependences - must execute branch to fetch next instructions - correct branch prediction/speculation: essentially eliminates control dependences - mispredictions are still a major bottleneck: complete squashing Introduction Page 3 Slide 3 •Solutions to branch misprediction bottleneck 1. better branch prediction 2. forms of multi-path execution 3. predication 4. control independence Introduction Page 4 Slide 4 Control Independence branch correct control dependent instructions incorrect control dependent instructions control independent instructions re-convergent point false data dependences wasted resources true data dependences Page 5 Slide 5 1. Establish new …