Bug #20195: 3.3.0 YJIT mishandles ruby2_keywords splat into methods taking a rest parameter

• Status: Closed
• Assignee: -
• Target version: -
• Backport: 3.0: DONTNEED, 3.1: DONTNEED, 3.2: DONTNEED, 3.3: REQUIRED

[alanwu (Alan Wu)]

Check with:

ruby2_keywords def foo(*args) = args

def bar(*args, **kw) = [args, kw]

def pass_bar(*args) = bar(*args)

def body
  args = foo(a: 1)
  pass_bar(*args)
end

p body

$ ruby ../test.rb
[[{:a=>1}], {}]
$ ruby --yjit-call-threshold=1 ../test.rb
[[], {:a=>1}]

Fix at: https://github.com/ruby/ruby/pull/9621

[alanwu (Alan Wu)]

• Subject changed from 3.3.0 YJIT mishandles splat into methods taking a rest parameter to 3.3.0 YJIT mishandles ruby2_keywords splat into methods taking a rest parameter

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Closed

[alanwu (Alan Wu)]

• Description updated (diff)

[alanwu (Alan Wu)]

• Description updated (diff)
• Status changed from Closed to Open

[alanwu (Alan Wu)]

• Status changed from Open to Closed

Applied in changeset git|ac1e9e443a0d6a4d4c0801c26d1d8bd33d9eb431.

---

YJIT: Fix ruby2_keywords splat+rest and drop bogus checks

YJIT didn't guard for ruby2_keywords hash in case of splat calls that
land in methods with a rest parameter, creating incorrect results.

The compile-time checks didn't correspond to any actual effects of
ruby2_keywords, so it was masking this bug and YJIT was needlessly
refusing to compile some code. About 16% of fallback reasons in
lobsters was due to the ISeq check.

We already handle the tagging part with
exit_if_supplying_kw_and_has_no_kw() and should now have a dynamic guard
for all splat cases.

Note for backporting: You also need 7f51959ff1.

[Bug #20195]