I worked on LLVM/ISPC with Matt in ~2011. I continued the work of Bruno Lopes on implementing AVX in LLVM, and Matt was one of the few people outside our team who was excited about this work. He provided excellent test cases in LLVM-IR. Matt is such a pleasant person and I really enjoyed our interaction.

Post on nice interactions with the LLVM team coming up in a few days. :-)

There are several other parts too:

Part 1: http://pharr.org/matt/blog/2018/04/18/ispc-origins.html

Part 3: http://pharr.org/matt/blog/2018/04/20/ispc-volta-going-all-i...

Part 4: http://pharr.org/matt/blog/2018/04/21/ispc-volta-c-and-spmd....

In general, anything Matt writes is a worthwhile read. =)