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C++Now 2018: Matt Godbolt “What Else Has My Compiler Done For Me Lately?”

Matt Godbolt, creator of Compiler Explorer, tours surprising optimizations modern compilers perform, such as turning loops into closed-form sums and using popcount instructions. He explores what the compiler does behind the scenes.

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Why HN readers recommended it

HN recommends it as a detailed, entertaining look at the crazy optimizations compilers do.

This is a summary from the source dataset, not an endorsement by Hacker News or the video creator.

Video & recommendation details

Creator / channel
CppNow
Topic
compiler optimizations
Format
talk
Level
intermediate
HN recommenders in dataset
3
HN mentions in dataset
4
Recommendation years in dataset
2018–2020

These counts and years describe the included Hacker News records; they are not YouTube views or the video’s publication date.

From the original HN conversations

Excerpts from the recorded comments. Follow each source for the full comment and surrounding discussion.

  • 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 …

    snailmailman on Hacker News · 2019-09
    In Popcount CPU instruction

  • This is not Rust specific, this is a compiler thing, both LLVM and GCC can detect sums and generate closed form formulas instead. There are other fun algorithm detections - e.g. if you try to do bitcounts yourself, LLVM will use popcnt instead. Compilers are …

    drej on Hacker News · 2020-02
    In Rust: Zero-Cost Abstraction in Action

  • 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” [LINK] . And the follow up [VIDEO] .

    manaskarekar on Hacker News · 2020-04
    In I translated a simple C program to x86_64 and it was slower

Summaries, classifications and recommendation records are from the HackerTube source dataset. Read about this library and its limitations.

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