feat(ir): implement HoistConstant rule for lifting py.Constant in ilist.ForEach|ilist.Map

[zhenrongliew]

Adds HoistConstant, a rewrite that lifts py.Constant statements out of the closure bodies passed to ilist.ForEach / ilist.Map, and re-introduces them as closure captures.

# before                                    # after
%x = py.constant.constant 10                %x = py.constant.constant 10
%body = func.lambda body(%x) {              %hoisted = py.constant.constant 2
  ^1(%body_self, %i):                       %body = func.lambda body(%x, %hoisted) {
  │ %x_1 = func.getfield(%body_self, 0)       ^1(%body_self, %i):
  │ %4   = py.constant.constant 2             │ %4   = func.getfield(%body_self, 1)
  │ %5   = py.binop.mult(%x_1, %4)            │ %x_1 = func.getfield(%body_self, 0)
  │ %6   = py.binop.add(%5, %i)               │ %5   = py.binop.mult(%x_1, %4)
}                                             │ %6   = py.binop.add(%5, %i)
py.ilist.map(fn=%body, collection=%2)       }
                                            py.ilist.map(fn=%body, collection=%2)

Tested behavior:

• ilist.ForEach/ilist.Map` , constants leave the body, captures grow.
• Loop-variant ops stay put, only constants.
• py.Constant appear before lambda.
• Nested fixpoint, hoist through nested closures.
• Newly folded constants also hoist.
• Idempotent.

closes #698

[github-actions]

☂️ Code Coverage

current status: ✅

Overall Coverage

Statements	Covered	Coverage	Threshold	Status
11740	10581	90%	0%	🟢

New Files

File	Coverage	Status
src/kirin/dialects/ilist/rewrite/hoist_constant.py	91%	🟢
TOTAL	91%	🟢

Modified Files

File	Coverage	Status
src/kirin/dialects/ilist/rewrite/_init_.py	100%	🟢
TOTAL	100%	🟢

updated for commit: 33a3166 by action🐍

[github-actions]

PR Preview Action v1.8.1
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2026-09-25 15:46 UTC

[codecov]

Codecov Report

❌ Patch coverage is 91.66667% with 4 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/kirin/dialects/ilist/rewrite/hoist_constant.py	91.48%	4 Missing ⚠️

📢 Thoughts on this report? Let us know!

[neelay893]

LGTM