Making ilist.rewrite.HintLen less aggressive

[weinbe58]

because of issue: #512 I am adding a slight modification to HintLen so it will not add hints inside For/IfElse bodies as that is causing some other passes to fail for example in AddressiveUnroll in bloqade-circuit the following example doesn't unroll properly:

from bloqade import qubit, squin
from kirin.dialects import ilist
from bloqade.rewrite.passes.aggressive_unroll import AggressiveUnroll

@squin.kernel(typeinfer=True, fold=True)
def log_depth_ghz():
    size = 8
    q0 = qubit.new()
    squin.h(q0)
    reg = ilist.IList([q0])
    for i in range(size):
        current = len(reg)
        missing = size - current
        if missing > current:
            num_alloc = current
        else:
            num_alloc = missing

        if num_alloc > 0:
            new_qubits = qubit.qalloc(num_alloc)
            squin.broadcast.cx(reg[:num_alloc], new_qubits)
            reg = reg + new_qubits

unroll = AggressiveUnroll(log_depth_ghz.dialects, no_raise=True)
result = unroll.fixpoint(log_depth_ghz)
log_depth_ghz.print()

Before this PR:

func.func @log_depth_ghz() -> !py.NoneType {
  ^0(%log_depth_ghz_self):
  │           %q0 = qubit.new() : !py.Qubit
  │          %reg = py.ilist.new(values=(%q0)){elem_type=!py.Qubit} : !py.IList[!py.Qubit, Literal(1,int)]
  │                 squin.gate.h(qubits=%reg)
  │            %0 = qubit.new() : !py.Qubit
  │   %new_qubits = py.ilist.new(values=(%0)){elem_type=!Any} : !py.IList[!py.Qubit, Literal(1,int)]
  │                 squin.gate.cx(controls=%reg, targets=%new_qubits)
  │            %1 = qubit.new() : !py.Qubit
  │ %new_qubits_1 = py.ilist.new(values=(%1)){elem_type=!Any} : !py.IList[!py.Qubit, Literal(1,int)]
  │                 squin.gate.cx(controls=%reg, targets=%new_qubits_1)
  │            %2 = qubit.new() : !py.Qubit
  │ %new_qubits_2 = py.ilist.new(values=(%2)){elem_type=!Any} : !py.IList[!py.Qubit, Literal(1,int)]
  │                 squin.gate.cx(controls=%reg, targets=%new_qubits_2)
  │            %3 = qubit.new() : !py.Qubit
  │ %new_qubits_3 = py.ilist.new(values=(%3)){elem_type=!Any} : !py.IList[!py.Qubit, Literal(1,int)]
  │                 squin.gate.cx(controls=%reg, targets=%new_qubits_3)
  │            %4 = qubit.new() : !py.Qubit
  │ %new_qubits_4 = py.ilist.new(values=(%4)){elem_type=!Any} : !py.IList[!py.Qubit, Literal(1,int)]
  │                 squin.gate.cx(controls=%reg, targets=%new_qubits_4)
  │            %5 = qubit.new() : !py.Qubit
  │ %new_qubits_5 = py.ilist.new(values=(%5)){elem_type=!Any} : !py.IList[!py.Qubit, Literal(1,int)]
  │                 squin.gate.cx(controls=%reg, targets=%new_qubits_5)
  │            %6 = qubit.new() : !py.Qubit
  │ %new_qubits_6 = py.ilist.new(values=(%6)){elem_type=!Any} : !py.IList[!py.Qubit, Literal(1,int)]
  │                 squin.gate.cx(controls=%reg, targets=%new_qubits_6)
  │            %7 = qubit.new() : !py.Qubit
  │ %new_qubits_7 = py.ilist.new(values=(%7)){elem_type=!Any} : !py.IList[!py.Qubit, Literal(1,int)]
  │                 squin.gate.cx(controls=%reg, targets=%new_qubits_7)
  │            %8 = func.const.none() : !py.NoneType
  │                 func.return %8

After this PR:

func.func @main() -> !py.NoneType {
  ^0(%main_self):
  │           %q0 = qubit.new() : !py.Qubit
  │          %reg = py.ilist.new(values=(%q0)){elem_type=!py.Qubit} : !py.IList[!py.Qubit, Literal(1,int)]
  │                 squin.gate.h(qubits=%reg)
  │            %0 = qubit.new() : !py.Qubit
  │   %new_qubits = py.ilist.new(values=(%0)){elem_type=!Any} : !py.IList[!py.Qubit, Literal(1,int)]
  │                 squin.gate.cx(controls=%reg, targets=%new_qubits)
  │            %1 = qubit.new() : !py.Qubit
  │            %2 = qubit.new() : !py.Qubit
  │ %new_qubits_1 = py.ilist.new(values=(%1, %2)){elem_type=!Any} : !py.IList[!py.Qubit, Literal(2,int)]
  │     %controls = py.ilist.new(values=(%q0, %0)){elem_type=!Any} : !py.IList[!py.Qubit, Literal(2,int)]
  │                 squin.gate.cx(controls=%controls, targets=%new_qubits_1)
  │            %3 = qubit.new() : !py.Qubit
  │            %4 = qubit.new() : !py.Qubit
  │            %5 = qubit.new() : !py.Qubit
  │            %6 = qubit.new() : !py.Qubit
  │ %new_qubits_2 = py.ilist.new(values=(%3, %4, %5, %6)){elem_type=!Any} : !py.IList[!py.Qubit, Literal(4,int)]
  │   %controls_1 = py.ilist.new(values=(%q0, %0, %1, %2)){elem_type=!Any} : !py.IList[!py.Qubit, Literal(4,int)]
  │                 squin.gate.cx(controls=%controls_1, targets=%new_qubits_2)
  │            %7 = func.const.none() : !py.NoneType
  │                 func.return %7
} // func.func main

which is clearly correct

The issue is because the type inference result for reg is wrong inside the for loop that means that current = len(reg) is being replaced with current = 1 which after unrolling propagates an incorrect value for every iteration after unrolling the loop. If you do not add hints inside the for loop body this will not happen so the program unrolls correctly.

In principle we do not need to be as aggressive with this rewrite rule anyways as we do not unroll inner loops, therefore, adding hints inside the body of a loop is not really necessary.

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☂️ Python Coverage

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Lines	Covered	Coverage	Threshold	Status
11734	10469	89%	0%	🟢

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Modified Files

File	Coverage	Status
src/kirin/dialects/ilist/rewrite/hint_len.py	92%	🟢
TOTAL	92%	🟢

updated for commit: ed3c04e by action🐍

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2025-12-01 21:03 UTC