Bug #19444: YJIT String#+@ miscompilations

• Status: Closed
• Assignee: -
• Target version: -
• Backport: 2.7: DONTNEED, 3.0: DONTNEED, 3.1: DONTNEED, 3.2: DONE

[alanwu (Alan Wu)]

We noticed two issues with YJIT's String#+@ (String unary plus) implementation.

1. It has issues with GC allocation tracing. We saw it SEGV with the Stackprof gem
2. It has a type confusion issue from assuming that the method always return an ::String instance. It can return subclass instances

The YJIT override does not exist on the 3.1 series.

[alanwu (Alan Wu)]

• Status changed from Open to Closed

Applied in changeset git|c178926fbe879045fa711444a1fd9e906af23e3b.

---

YJIT: jit_prepare_routine_call() for String#+@ missing

We saw SEGVs due to this when running with StackProf, which needs a
correct PC for RUBY_INTERNAL_EVENT_NEWOBJ, the same event used for
ObjectSpace allocation tracing.

[Bug #19444]

[byroot (Jean Boussier)]

• Backport changed from 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: REQUIRED to 2.7: DONTNEED, 3.0: DONTNEED, 3.1: DONTNEED, 3.2: REQUIRED

[naruse (Yui NARUSE)]

• Backport changed from 2.7: DONTNEED, 3.0: DONTNEED, 3.1: DONTNEED, 3.2: REQUIRED to 2.7: DONTNEED, 3.0: DONTNEED, 3.1: DONTNEED, 3.2: DONE

ruby_3_2 4d75035e1762a23d38c5192b30bb47f40b752bee merged revision(s) c178926fbe879045fa711444a1fd9e906af23e3b,a4b7ec12298c78392797e5ba7704076550e4f100.