`--llzk-duplicate-op-elim` reuses stateful reads across writes/stores

[1sgtpepper]

Summary

--llzk-duplicate-op-elim can reuse a global.read or ram.load across an intervening write/store to the same state.

Reproduction

Reproducer run:
https://github.com/Kuhai9801/llzk-lib/actions/runs/28180228869

Global read/write:

global.def @g : !felt.type = 1

function.def @compute() -> !struct.type<@GlobalState> {
  %self = struct.new : !struct.type<@GlobalState>
  %two = felt.const 2
  %before = global.read @g : !felt.type
  global.write @g = %two : !felt.type
  %after = global.read @g : !felt.type
  struct.writem %self[@out] = %after : !struct.type<@GlobalState>, !felt.type
  function.return %self : !struct.type<@GlobalState>
}

Run: llzk-opt --llzk-duplicate-op-elim repro.llzk

Actual: later uses are rewritten to the first global.read / ram.load.

Expected

The second global.read @g and second ram.load %addr remain after the intervening write/store.

Actual

The later read/load is removed and its uses are rewritten to the earlier read/load result.

Notes

The relevant pass is in lib/Transforms/LLZKRedundantOperationEliminationPass.cpp.