Chapter 10 #34
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Chapter 10 #34
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Thanks Amir, I will accept your |
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No problem, I was just editing the text offline from cli, hence the reflow. |
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I will make my cosmetic changes in a separate commit. |
dendibakh
reviewed
Dec 1, 2023
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| Perhaps, the only direct way to get rid of branch mispredictions is to get rid of the branch itself. In the two subsequent sections, we will take a look at how branches can be replaced with lookup tables and predication. | ||
| \personal{There is a conventional wisdom that never taken branches are transparent to the branch prediction and can't affect performance, and therefore it doesn't make much sense to remove them, at least from prediction perspective. However, contrary to the wisdom, an experiment conducted by BOLT authors demonstrated that replacing never taken branches with equal-sized no-ops in a large code footprint application (Clang binary) leads to approx. 5\% speedup on modern Intel CPUs. So it still pays to try to eliminate all branches.} |
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Reflow and add some bits about 3 Cs, code layout effects, and perf impact of never taken branches.