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+++ This bug was initially created as a clone of Bug #2177696 +++

Description of problem:

Qt's V4 JIT engine generates bad JIT code that corrupts JS stack slots, causing random garbage collector crashes later on. On a vanilla KDE Plasma setup, this can cause plasmashell to sometimes or consistently crash, depending on the alignment of the stars (sometimes sessions are completely unusable). See below for a consistent repro.

Version-Release number of selected component (if applicable): 

5.15.3-1.el9

How reproducible:

Randomly by default, 100% with QV4_MM_AGGRESSIVE_GC=1, never with QV4_FORCE_INTERPRETER=1.

Steps to Reproduce:
1. Start a KDE Plasma session
2. killall plasmashell
3. QV4_MM_AGGRESSIVE_GC=1 plasmashell

Actual results:

plasmashell instantly segfaults

Expected results:

plasmashell does not segfault

Additional info:

Example of the bad JIT code here:

https://social.treehouse.systems/@marcan/110015722134175810

The issue is a missing accumulator save/restore around a call to PushCallContext.

This is generic code, so this is actually broken on *all architectures* in principle, it's just that ARM64 got unlucky with the register clobbering and value encoding lottery and ended up with actual crashes.

Upstream report: https://bugreports.qt.io/browse/QTBUG-111935

Upstream fix: https://codereview.qt-project.org/c/qt/qtdeclarative/+/466808

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (Moderate: qt5 security and bug fix update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2023:6369