--- title: "My friend, the compiler" url: https://daily.dev/posts/my-friend-the-compiler-zfr9rsozt source_url: https://www.embeddedrelated.com/showarticle/1692.php type: article source: "EmbeddedRelated" published: 2026-05-31T07:48:07.806Z updated: 2026-05-31T09:10:51.073Z tags: ["c", "embedded", "compiler-optimization"] reading_time: 10 upvotes: 0 comments: 0 language: 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. # My friend, the compiler **[EmbeddedRelated](https://daily.dev/sources/embeddedrelated)** · 10 min read · 0 upvotes · 0 comments ## Summary While implementing a byte-to-hex converter in C for an 8-bit ATmega4809 AVR microcontroller, the author discovered that the compiler already used the AVR's SWAP instruction to efficiently isolate nybbles — something the author thought would require manual optimization. The post serves as a reminder to inspect disassembly output and measure speed-critical code paths rather than assuming you need to outsmart the compiler. It also covers various algorithmic options for byte-to-hex and hex-to-byte conversion on constrained hardware, and raises the question of how to reliably trust compiler optimizations across code revisions. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Too much Discussion of the XOR swap trick – Heather Cafe](https://daily.dev/posts/too-much-discussion-of-the-xor-swap-trick-heather-cafe-7zbqi1yr9) · Hacker News · 2 upvotes · 0 comments - [your hex editor should color-code bytes](https://daily.dev/posts/your-hex-editor-should-color-code-bytes-egdggkkzq) · Lobsters · 8 upvotes · 1 comments --- Tags: [#c](https://daily.dev/tags/c), [#embedded](https://daily.dev/tags/embedded), [#compiler-optimization](https://daily.dev/tags/compiler-optimization) [View this post on daily.dev](https://daily.dev/posts/my-friend-the-compiler-zfr9rsozt)