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[[Category:SPO600 Labs]]
{{Admon/lab|Purpose of this Lab|This lab is designed to explore single instruction/multiple data (SIMD) vectorization, and the auto-vectorization capabilities of the GCC compiler.}}
== Lab 6 ==
# Write the shortest C a short program that can be vectorized by GCCcreates two 1000-element integer arrays and fills them with random numbers, then sums those two arrays to a third array, and finally sums the third array to a long int and prints the result.# Compile this program on [[SPO600 Servers#AArch64|aarchie]]in such a way that the code is auto-vectorized.
# Annotate the emitted code (i.e., obtain a dissassembly via <code>objdump -d</code> and add comments to the instructions in <code><main></code> explaining what the code does).
# '''Write a blog post discussing your findings'''. Include:
#* Your annotated dissassembly listing
#* Your reflections on the experience and the results
=== Resources ===
* [https://gcc.gnu.org/projects/tree-ssa/vectorization.html Auto-Vectorization in GCC] - Main project page for the GCC auto-vectorizer.
* [http://locklessinc.com/articles/vectorize/ Auto-vectorization with gcc 4.7] - An excellent discussion of the capabilities and limitations of the GCC auto-vectorizer, intrinsics for providing hints to GCC, and other code pattern changes that can improve results. Note that there has been some improvement in the auto-vectorizer since this article was written. '''This article is strongly recommended.'''