{
  "id": 15627543,
  "title": "Making all divisions slower to fix a bug in 0.000000000000000000542% of cases",
  "url": "https://urgent.news/2026/10/19/making-all-divisions-slower-to-fix-a-bug-in-0-000000000000000000542",
  "topic": "tech",
  "section": "Tech",
  "published": "2026-10-19T16:42:07.000Z",
  "source": {
    "name": "Lobsters",
    "slug": "lobsters",
    "url": "https://futhark-lang.org/blog/2026-10-14-defining-division.html"
  },
  "original_language": "en",
  "account": "For languages like Futhark, which define signed integer overflow as a legal operation, generating correct C code is tricky due to C's undefined behavior surrounding signed integer overflow. The source material explains that the most negative signed integer cannot be represented as a positive number in two's complement representation, leading to issues when attempting to divide by -1. This results in signed integer overflow, a scenario that C handles as undefined behavior. Consequently, if the most negative signed integer is divided by -1, the correct result cannot be represented in signed integers, causing undefined behavior in C, and potentially triggering a CPU exception on x86 architectures. The Futhark compiler resolves this by generating signed C division, but this approach fails for the most negative number where the result would be out of range. To address this, the Futhark runtime system introduces a workaround ensuring correct arithmetic even in edge cases, thereby avoiding undefined behavior and crashing programs.",
  "summary": null,
  "key_points": [
    "Futhark defines signed integer overflow as legal operation",
    "Dividing most negative signed integer by -1 causes overflow",
    "Futhark runtime system generates workaround for edge cases"
  ],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}