fix(lowering): order if/else phi and yield names by first definition

[zhenrongliew]

Fixes #775.

lower_If in both the cf and scf lowerings collected the names that need a join argument (cf) or a yield (scf) in a set[str], then built the IR by iterating it. String hashes are randomized per process, so the same kernel lowered to IR with a different argument/yield order in each process. Each lowering was still correct, because every loop iterates the same set, but the IR text and any hash of it changed between runs.

This causes misses in the on-disk compile cache (#769). The key is computed from the lowered IR, so a new process often computes a new key for an unchanged kernel, then recompiles it and saves another copy. Callers are affected too, because a kernel's key includes its callees' keys.

Changes

• dialects/lowering/cf.py: phi is a dict[str, None] instead of a set[str].
• dialects/scf/lowering.py: all_names = dict.fromkeys([*body_frame.defs, *else_frame.defs]).

Names now come out in the order they are first defined: the condition, then the then-branch's names, then names assigned only in the else branch.

Tests

• New test_ifelse_order_independent_of_hash_seed (test/lowering/test_ifelse.py) lowers one if/else with basic_no_opt and structural_no_opt in fresh processes under 4 hash seeds, and checks that every run gives ['flag', 'x', 'y']. On main it fails: 4 seeds give 4 different orders.
• The full suite passes under several hash seeds.

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PR Preview Action v1.8.1
Preview removed because the pull request was closed.
2026-10-13 13:18 UTC

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☂️ Code Coverage

current status: ✅

Overall Coverage

Statements	Covered	Coverage	Threshold	Status
12307	11132	90%	0%	🟢

New Files

No new covered files...

Modified Files

File	Coverage	Status
src/kirin/dialects/lowering/cf.py	96%	🟢
src/kirin/dialects/scf/lowering.py	96%	🟢
TOTAL	96%	🟢

updated for commit: ca252de by action🐍

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Codecov Report

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Backport results for 9be49b5

Succeeded:

• release-0-22: Backport PR #777 to release-0-22 #780