--- title: Two studies in compiler optimisations · hmpc | daily.dev description: A deep dive into LLVM's optimization pipeline using two concrete C++ examples: modular increment and endianness conversion. Explores how passes like... canonical: https://daily.dev/posts/two-studies-in-compiler-optimisations-hmpc-scky7w9iq twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Two studies in compiler optimisations · hmpc | daily.dev og:description: A deep dive into LLVM's optimization pipeline using two concrete C++ examples: modular increment and endianness conversion. Explores how passes like... og:url: https://daily.dev/posts/two-studies-in-compiler-optimisations-hmpc-scky7w9iq og:image: https://api.daily.dev/og/posts/sCKY7w9IQ.png og:image:alt: Two studies in compiler optimisations · hmpc og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Two studies in compiler optimisations · hmpc **[Hacker News](https://daily.dev/sources/hn)** · 26 min read · 0 upvotes · 0 comments ## Summary A deep dive into LLVM's optimization pipeline using two concrete C++ examples: modular increment and endianness conversion. Explores how passes like InstCombine, AggressiveInstCombine, DAGCombiner, and CodeGenPrepare interact, how pass ordering affects results, and how small source changes (using `[[assume]]`, templates, auxiliary variables) can dramatically alter which optimization paths are triggered. Demonstrates both the power and the surprising limitations of modern compiler optimizers, with practical takeaways on writing compiler-friendly code. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Writing a Fast Compiler](https://daily.dev/posts/writing-a-fast-compiler-5hnqshf7f) · Lobsters · 0 upvotes · 0 comments - [When compilers surprise you — Matt Godbolt’s blog](https://daily.dev/posts/when-compilers-surprise-you-matt-godbolt-s-blog-3c6va0gvq) · Hacker News · 1 upvotes · 0 comments - [Open wide: Inspecting LLVM 21 with static analysis](https://daily.dev/posts/open-wide-inspecting-llvm-21-with-static-analysis-g8igvhksx) · C\+\+ · 0 upvotes · 0 comments - [You can't fool the optimiser — Matt Godbolt’s blog](https://daily.dev/posts/you-can-t-fool-the-optimiser-matt-godbolt-s-blog-mx5wozyqn) · Hacker News · 1 upvotes · 0 comments --- Tags: [#c++](https://daily.dev/tags/c++), [#compiler-optimization](https://daily.dev/tags/compiler-optimization), [#general-programming](https://daily.dev/tags/general-programming) [View this post on daily.dev](https://daily.dev/posts/two-studies-in-compiler-optimisations-hmpc-scky7w9iq) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Two studies in compiler optimisations · hmpc","url":"https://daily.dev/posts/two-studies-in-compiler-optimisations-hmpc-scky7w9iq","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/two-studies-in-compiler-optimisations-hmpc-scky7w9iq"},"datePublished":"2026-03-26T10:11:29.872Z","dateModified":"2026-03-30T02:19:05.007Z","description":"A deep dive into LLVM's optimization pipeline using two concrete C++ examples: modular increment and endianness conversion. 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