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+title = "Trace scheduling"
+author = "Yann Herklotz"
+tags = []
+categories = []
+backlinks = ["1c2h", "1c2e"]
+forwardlinks = ["1c2b", "1c2g"]
+zettelid = "1c2f"
++++
+
+Trace scheduling \[1\], \[2\], is a technique used to do global
+scheduling of the code. This is different to list scheduling ([\#1c2b]),
+where the scheduling is only done for one basic block.
+
+The way this is done is by looking through the most common trace through
+a program and then regarding that path as not containing any control
+flow. Normal scheduling techniques can then be applied on this path,
+which is now straight-line code, such as placing instructions into
+larger instruction words, like with VLIW processors.
+
+However, to counter-act this, instructions need to also be placed into
+other possible execution paths apart from the trace, as the above
+scheduling might have gotten rid of instructions and change the
+behaviour of the program.
+
+After the correctness has been restored, another trace is taken and the
+same operation is performed.
+
+<div id="refs" class="references csl-bib-body" markdown="1">
+
+<div id="ref-fisher81_trace_sched" class="csl-entry" markdown="1">
+
+<span class="csl-left-margin">\[1\]
+</span><span class="csl-right-inline">J. A. Fisher, “Trace scheduling: A
+technique for global microcode compaction,” *IEEE Transactions on
+Computers*, vol. C–30, no. 7, pp. 478–490, 1981, doi:
+[10.1109/TC.1981.1675827].</span>
+
+</div>
+
+<div id="ref-colwell88_vliw" class="csl-entry" markdown="1">
+
+<span class="csl-left-margin">\[2\]
+</span><span class="csl-right-inline">R. P. Colwell, R. P. Nix, J. J.
+O’Donnell, D. B. Papworth, and P. K. Rodman, “A VLIW architecture for a
+trace scheduling compiler,” *IEEE Transactions on Computers*, vol. 37,
+no. 8, pp. 967–979, 1988, doi: [10.1109/12.2247].</span>
+
+</div>
+
+</div>
+
+  [\#1c2b]: /zettel/1c2b
+  [10.1109/TC.1981.1675827]: https://doi.org/10.1109/TC.1981.1675827
+  [10.1109/12.2247]: https://doi.org/10.1109/12.2247