CppCon 2017: Matt Godbolt “What Has My Compiler Done for Me Lately? Unbolting the Compiler's Lid”
Why Hacker News recommends it
HN recommends it as an entertaining, mind-blowing look at compiler cleverness from a great speaker.
What it is
Matt Godbolt's CppCon 2017 talk shows what modern compilers do with your C++ code, using Compiler Explorer to inspect generated assembly. It covers surprising optimizations and how the tool works.
Recommended by 7 HN commenters across 6 different months, 2018 to 2022.
What Hacker News said
Strong rec drej · 2018-12 · on “Compiler Explorer”
Matt Godbolt is a great speaker as well. I loved this talk that included a bit about the architecture behind his Compiler Explorer. The rest of his talk is super cool as well. E.g. closed form solutions from O(n) code? Compilers are awesome. [this video]
Strong rec snailmailman · 2019-09 · on “Popcount CPU instruction”
I highly recommend Matt Godbolt's talk "What has my compiler done for me lately?"[0] and its follow-up[1]. Both are great presentations going into details on some of the crazy optimizations compilers will do. As someone who knows very little about the inner workings of compilers my mind was blown when I saw some them. [0] [this video] [1] [LINK]
Recommends pkaye · 2018-01 · on “Outperforming LAPACK with C++ metaprogramming”
You should check out this presentation done by Matt Godbolt about compiler internals. He talks about what kind of optimizations are being done by GCC and Clang. Pretty amazing stuff. For example, the compiler will figure out you are trying to write a pop count in high level code and replace it with a single popcount instruction. [this video]
Recommends highesttide · 2018-10 · on “Ask HN: What are some of the best technical talks you've heard?”
What has my compiler done for me lately? - Matt Godbolt [this video] Entertaining talk, not extremely in depth, though.
Recommends drej · 2018-10 · on “C++: Associative map containers with compile-time lookup”
CppCon has super interesting content. That comes from a person who has written maybe two dozen lines of C++ code, mostly just hello world. E.g. this talk by Matt Godbolt or anything by Chadler Carruth. [this video]
Recommends fps_doug · 2019-09 · on “Color Emulation”
But please keep in mind that today's compilers are (most of the time) very smart. Hacker's Delight is somewhat outdated today. There's no need anymore for writing "x << 2" instead of "x * 4". I recommend Matt Godbolt's Talk(s) about compiler cleverness: [this video] (see the 30 minute mark for the multiplication example)
Recommends manaskarekar · 2020-04 · on “I translated a simple C program to x86_64 and it was slower”
Tangent, but this reminds me of this great talk by Matt Godbolt from CppCon 2017: “What Has My Compiler Done for Me Lately? Unbolting the Compiler's Lid” [this video] . And the follow up [LINK] .
Recommends s3cur3 · 2021-03 · on “Performance comparison: counting words in Python, Go, C++, C, Awk, Forth, Rust”
Link to the (great) CppCon talk: [this video] The one thing I would say is: as you dig more into C++ perf, you can develop an intuition for the kinds of things the compiler can and can't optimize. For instance, the C++ example from the article uses `std::unordered_map`, which is just an absolute mess from a cache locality perspective—the best compilers today (or of the foreseeable future) can't do a thing to fix that. Improving the programmer's choice of data structure is just not on the radar. :(