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[Bug 2111216] Re: Qt V4 JIT engine generates bad JIT code

 

** Also affects: qtdeclarative-opensource-src (Ubuntu Noble)
   Importance: Undecided
       Status: New

** Changed in: qtdeclarative-opensource-src (Ubuntu)
       Status: New => Fix Released

** Changed in: qtdeclarative-opensource-src (Ubuntu Noble)
       Status: New => Triaged

** Changed in: qtdeclarative-opensource-src (Ubuntu Noble)
     Assignee: (unassigned) => Dmitry Shachnev (mitya57)

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https://bugs.launchpad.net/bugs/2111216

Title:
  Qt V4 JIT engine generates bad JIT code

Status in qtdeclarative-opensource-src package in Ubuntu:
  Fix Released
Status in qtdeclarative-opensource-src source package in Noble:
  Triaged

Bug description:
  We're encountering a critical issue in Qt 5.15.13 as shipped in Ubuntu
  24.04 (Noble). The Qt V4 JIT engine occasionally generates invalid
  machine code, resulting in crashes at runtime.

  This issue is tracked upstream as QTBUG-111935 [0], and was fixed in
  Qt 5.15.14.

  Symptoms:
      * Application crashes with segmentation faults or illegal instruction errors when executing certain JavaScript in QML (GC).
      * The issue appears to stem from bad register allocation or incorrect code paths during JIT compilation.

  Affected Package:
  qtdeclarative-opensource-src version 5.15.13 in Ubuntu Noble

  Upstream Fix:

  Commit that resolves the issue:

  qt/qtdeclarative@3bd18f4 [1] or attached patch
      JIT: Add missing {STORE|LOAD}_ACC() to CreateCallContext

  Would it be possible to Cherry-pick the above fix into the current Qt
  5.15.13 package in Noble?

  I’m only able to apply a downstream patch for now, but would prefer a
  shared fix in the official archive if feasible.

  Thanks for considering this!

  [0] https://bugreports.qt.io/browse/QTBUG-111935
  [1] https://github.com/qt/qtdeclarative/commit/3bd18f41cfb0f3da65eecf216e49a9bb6bda71a6

  — Marius

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References