fix(codegen): root the URLSearchParams receiver across the name lowering

[proggeramlug]

Six more sites of #7453's shape, in the URLSearchParams family.

Confirmed in IR, not inferred

%r22 = and i64 %r21, 281474976710655           ; p_ptr — raw heap pointer
%r23 = call double @perry_fn_sp_root_ts__mk()  ; user call, can collect
%r24 = call i64 @js_url_search_params_get(i64 %r22, double %r23)

p_ptr is a raw heap pointer held across a full user function call.

Moving the unbox below the lowering would not fix it — p_v is the same pointer with a NaN-box tag on it, and a tagged pointer in an SSA register is exactly as invisible to the collector as an untagged one. That is worth stating because it is the obvious "fix" and it is wrong.

Both operands now go through lower_exprs_rooted, and the receiver is unboxed from the reloaded value:

%r22 = call i32 @js_gc_temp_root_push(i64 %r21)   ; root before
%r23 = call double @perry_fn_sp_root_ts__mk()
%r24 = call i64 @js_gc_temp_root_get(i32 %r22)    ; re-read after
%r26 = and i64 %r24, 281474976710655              ; unbox the RELOAD
%r27 = call i64 @js_url_search_params_get(i64 %r26, double %r23)
call void @js_gc_temp_root_truncate(i32 %r22)     ; release after use

Arms: Get, Has, Set, Append, Delete, GetAll.

One thing I got wrong first

An earlier draft bound the guard to _operand_guard. That compiled clean with no warnings and never emitted js_gc_temp_root_truncate — so every execution of these arms would push two temp roots and never pop them, growing the stack without bound in a loop. The release has to be placed after the consuming call (the consumer allocates while reading these values), and "it compiles" was not evidence that it was.

Verification

• 12/12 URL + URLSearchParams gap tests byte-identical to the pinned Node oracle
• repro exits 0 under PERRY_GC_HEAP_LIMIT=8 PERRY_GC_FORCE_EVACUATE=1
• before/after IR inspected directly at the same call site
• cargo fmt --check clean

Remaining

The scan found 11 sites of this shape in url_main.rs; these are the six uniform params + name arms. The other five (UrlSetHref's value lowering, and three arms where the receiver is lowered second) have different shapes and are left for a follow-up rather than being swept in with a mechanical edit.

Summary by CodeRabbit

• Bug Fixes
  • Improved reliability of URLSearchParams operations, including getting, checking, setting, appending, deleting, and retrieving all values.
  • Prevented potential failures during memory-management activity while these operations are running.
  • Added validation covering normal execution and forced memory relocation scenarios.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 20402c3b-9c9e-47d4-ab35-f43e533c8c3b

📥 Commits

Reviewing files that changed from the base of the PR and between 01d1249 and 7d7f8f3.

📒 Files selected for processing (2)

• changelog.d/7462-searchparams-receiver-rooting.md
• crates/perry-codegen/src/expr/url_main.rs

---

📝 Walkthrough

Walkthrough

This PR updates six URLSearchParams lowerings to root receiver and name operands together, reload rooted values before unboxing, and release the root guard after consuming runtime calls. It also adds a changelog entry for these rooting fixes.

Changes

URLSearchParams GC safety

Layer / File(s)	Summary
Root URLSearchParams operands before runtime calls crates/perry-codegen/src/expr/url_main.rs, changelog.d/7462-searchparams-receiver-rooting.md	UrlSearchParamsGet, Has, Set, Append, Delete, and GetAll now use rooted lowering for params and name, reload rooted values before unboxing or runtime calls, and release the temporary root guard after the consuming call where implemented. The changelog records the same receiver-rooting updates and validation notes.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related PRs

• PerryTS/perry#6972: Both PRs update codegen to use the lower_exprs_rooted and temp_root_release pattern for precise GC rooting.
• PerryTS/perry#6975: Both PRs fix GC-soundness gaps by switching lowering sites to rooted and reloaded operand handling.
• PerryTS/perry#6983: This PR extends the same precise-rooting fix pattern to URLSearchParams method lowerings.

Suggested reviewers: thehypnoo

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/layer1-searchparams-receiver-rooting

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}