--- title: Why does atan2 crash the zig compiler? (SPIR-V only of... description: A live coding stream transcript where the developer debugs two Zig compiler issues related to SPIR-V (GPU shader) code generation. The first bug involves... canonical: https://daily.dev/posts/why-does-atan2-crash-the-zig-compiler-spir-v-only-of-course--elmyupbmi twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Why does atan2 crash the zig compiler? (SPIR-V only of course) | daily.dev og:description: A live coding stream transcript where the developer debugs two Zig compiler issues related to SPIR-V (GPU shader) code generation. The first bug involves... og:url: https://daily.dev/posts/why-does-atan2-crash-the-zig-compiler-spir-v-only-of-course--elmyupbmi og:image: https://api.daily.dev/og/posts/eLmyUpbMi.png og:image:alt: Why does atan2 crash the zig compiler? (SPIR-V only of course) 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. # Why does atan2 crash the zig compiler? (SPIR-V only of course) **[sphaerophoria](https://daily.dev/sources/sphaerophoria)** · 131 min read · 0 upvotes · 0 comments ## Summary A live coding stream transcript where the developer debugs two Zig compiler issues related to SPIR-V (GPU shader) code generation. The first bug involves `atan2` crashing the compiler due to `std.mem.doNotOptimizeAway` emitting a C long bitcast that is invalid on SPIR-V (which has no C interop). The fix involves special-casing the SPIR-V target to skip the register-size check. The second bug involves invalid SPIR-V being generated because slice types (pointer + length) are used in shader code, but SPIR-V does not support function-scope pointers. The developer traces through SPIR-V disassembly, Zig's AIR (Analyzed IR), and the compiler's semantic analysis to identify and fix both issues, with the goal of GPU-accelerating an SVG renderer. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: --- Tags: [#gpu](https://daily.dev/tags/gpu), [#zig](https://daily.dev/tags/zig) [View this post on daily.dev](https://daily.dev/posts/why-does-atan2-crash-the-zig-compiler-spir-v-only-of-course--elmyupbmi) ```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":"Why does atan2 crash the zig compiler? 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