attempting to use cudaq.kernels.uccsd kernel with hardware backend fails at compilation

[ColemanCollins]

Required prerequisites

• Consult the security policy. If reporting a security vulnerability, do not report the bug using this form. Use the process described in the policy to report the issue.
• Make sure you've read the documentation. Your issue may be addressed there.
• Search the issue tracker to verify that this hasn't already been reported. +1 or comment there if it has.
• If possible, make a PR with a failing test to give us a starting point to work on!

Describe the bug

Any program that utilizes cudaq.kernels.uccsd against a hardware backend fails during what looks like a MLIR rewrite pass, per the failure output.

Steps to reproduce the bug

The following repro case, as written, runs successfully. If you uncomment line 3 or 4 (i.e. set target to a hardware backend), it fails with the output below.

import cudaq

# cudaq.set_target('ionq', emulate="true")
# cudaq.set_target('iqm', emulate=True, **{"qpu-architecture": "Adonis"})
repro_num_electrons = 2
repro_num_qubits = 4
repro_thetas = [-0.00037043841404585794, 0.0003811110195084151, 0.2286823796532558]

@cudaq.kernel
def repro_trial_state(qubits: cudaq.qvector, num_electrons:int, num_qubits:int, thetas:list[float]):
    for i in range(num_electrons):
        x(qubits[i])
    cudaq.kernels.uccsd(qubits, thetas, num_electrons, num_qubits)

# minimal repro case to play with IonQ submission issues
repro_kernel = cudaq.make_kernel()
repro_qubits = repro_kernel.qalloc(repro_num_qubits)
repro_kernel.apply_call(repro_trial_state, repro_qubits, repro_num_electrons, repro_num_qubits, repro_thetas)
repro_meas = cudaq.sample(repro_kernel, shots_count=100)
print(repro_meas)

healthy case

[2024-11-05 18:59:15.212] [info] [CircuitSimulator.h:1123] Setting current circuit name to
[2024-11-05 18:59:15.212] [info] [CircuitSimulator.h:1123] Setting current circuit name to
[2024-11-05 18:59:17.868] [info] [CircuitSimulator.h:901] Allocating 4 new qubits.
[2024-11-05 18:59:17.868] [info] [CircuitSimulator.h:1192] (apply) x(0)
[2024-11-05 18:59:17.868] [info] [CircuitSimulator.h:1192] (apply) x(1)
... more gate (apply) calls for x, h, rx, rz, ctrl -x gates
[2024-11-05 18:59:17.868] [info] [CircuitSimulator.h:1192] (apply) rx(-1.570796, 1)
[2024-11-05 18:59:17.868] [info] [CircuitSimulator.h:1192] (apply) rx(-1.570796, 0)
[2024-11-05 18:59:17.868] [info] [CircuitSimulator.h:968] Deferring qubit 0 deallocation
[2024-11-05 18:59:17.869] [info] [CircuitSimulator.h:968] Deferring qubit 1 deallocation
[2024-11-05 18:59:17.869] [info] [CircuitSimulator.h:968] Deferring qubit 2 deallocation
[2024-11-05 18:59:17.869] [info] [CircuitSimulator.h:968] Deferring qubit 3 deallocation
[2024-11-05 18:59:17.877] [info] [CircuitSimulator.h:656] Sampling the current state, with measure qubits = [0, 1, 2, 3]
[2024-11-05 18:59:17.877] [info] [CircuitSimulator.h:1108] Deallocated all qubits, reseting state vector.
{ 1100:100 }

failure case output - IonQ

[2024-11-05 18:59:37.151] [info] [DefaultQuantumPlatform.cpp:85] Backend string is ionq;emulate;true
[2024-11-05 18:59:37.151] [info] [DefaultQuantumPlatform.cpp:102] Config file path = /home/epifanovsky/miniconda3/envs/cudaq/lib/python3.11/site-packages/cudaq/mlir/_mlir_libs/../../../targets/ionq.yml
[2024-11-05 18:59:37.151] [info] [DefaultQuantumPlatform.cpp:120] Default platform QPU subtype name: remote_rest
[2024-11-05 18:59:37.151] [info] [BaseRemoteRESTQPU.h:205] Remote REST platform is targeting ionq;emulate;true.
[2024-11-05 18:59:37.151] [info] [BaseRemoteRESTQPU.h:260] Config file path = /home/epifanovsky/miniconda3/envs/cudaq/lib/python3.11/site-packages/cudaq/mlir/_mlir_libs/../../../targets/ionq.yml
[2024-11-05 18:59:37.151] [info] [BaseRemoteRESTQPU.h:270] Appending lowering pipeline: const-prop-complex,canonicalize,cse,lift-array-value,state-prep,expand-measurements,unrolling-pipeline,decomposition{enable-patterns=U3ToRotations},func.func(lower-to-cfg),canonicalize,func.func(multicontrol-decomposition),ionq-gate-set-mapping
[2024-11-05 18:59:37.151] [info] [BaseRemoteRESTQPU.h:276] Set codegen translation: qir-base
[2024-11-05 18:59:37.151] [info] [BaseRemoteRESTQPU.h:281] Adding post-codegen lowering pipeline: remove-measurements
[2024-11-05 18:59:37.151] [info] [IonQServerHelper.cpp:95] Initializing IonQ Backend.
[2024-11-05 18:59:37.151] [info] [quantum_platform.cpp:37] external caller setting the platform.
[2024-11-05 18:59:37.320] [info] [BaseRemoteRESTQPU.h:188] Remote Rest QPU setting execution context to sample
[2024-11-05 18:59:37.320] [info] [BaseRemoteRESTQPU.h:188] Remote Rest QPU setting execution context to sample
[2024-11-05 18:59:40.005] [info] [BaseRemoteRESTQPU.h:524] launching remote rest kernel (__nvqppBuilderKernel_LS0ORN02T4)
[2024-11-05 18:59:41.264] [info] [cudaq.cpp:226] Replacing code for kernel __nvqppBuilderKernel_LS0ORN02T4
[2024-11-05 18:59:41.266] [info] [BaseRemoteRESTQPU.h:392] Pass pipeline for __nvqppBuilderKernel_LS0ORN02T4 = cc-loop-unroll{allow-early-exit=0},canonicalize,const-prop-complex,canonicalize,cse,lift-array-value,state-prep,expand-measurements,unrolling-pipeline,decomposition{enable-patterns=U3ToRotations},func.func(lower-to-cfg),canonicalize,func.func(multicontrol-decomposition),ionq-gate-set-mapping
python: /llvm-project/mlir/lib/IR/PatternMatch.cpp:276: virtual void mlir::RewriterBase::eraseOp(mlir::Operation*): Assertion `op->use_empty() && "expected 'op' to have no uses"' failed.
Aborted

failure case output - IQM

[2024-11-05 19:23:12.356] [info] [BaseRemoteRESTQPU.h:270] Appending lowering pipeline: const-prop-complex,canonicalize,cse,lift-array-value,state-prep,expand-measurements,unrolling-pipeline,decomposition{enable-patterns=U3ToRotations},func.func(lower-to-cfg),canonicalize,func.func(multicontrol-decomposition),iqm-gate-set-mapping,func.func(add-dealloc,combine-quantum-alloc,canonicalize,factor-quantum-alloc,memtoreg,qubit-mapping{device=file(%QPU_ARCH%)},delay-measurements,regtomem),iqm-gate-set-mapping
[2024-11-05 19:23:12.356] [info] [BaseRemoteRESTQPU.h:276] Set codegen translation: iqm
[2024-11-05 19:23:12.356] [info] [IQMServerHelper.cpp:119] Emulation is enabled, ignore tokens file and IQM Server URL
[2024-11-05 19:23:12.356] [info] [quantum_platform.cpp:37] external caller setting the platform.
[2024-11-05 19:23:12.519] [info] [BaseRemoteRESTQPU.h:188] Remote Rest QPU setting execution context to sample
[2024-11-05 19:23:12.519] [info] [BaseRemoteRESTQPU.h:188] Remote Rest QPU setting execution context to sample
[2024-11-05 19:23:15.180] [info] [BaseRemoteRESTQPU.h:524] launching remote rest kernel (__nvqppBuilderKernel_3NA4U8G38W)
[2024-11-05 19:23:16.423] [info] [cudaq.cpp:226] Replacing code for kernel __nvqppBuilderKernel_3NA4U8G38W
[2024-11-05 19:23:16.425] [info] [BaseRemoteRESTQPU.h:392] Pass pipeline for __nvqppBuilderKernel_3NA4U8G38W = cc-loop-unroll{allow-early-exit=0},canonicalize,const-prop-complex,canonicalize,cse,lift-array-value,state-prep,expand-measurements,unrolling-pipeline,decomposition{enable-patterns=U3ToRotations},func.func(lower-to-cfg),canonicalize,func.func(multicontrol-decomposition),iqm-gate-set-mapping,func.func(add-dealloc,combine-quantum-alloc,canonicalize,factor-quantum-alloc,memtoreg,qubit-mapping{device=file('/home/epifanovsky/miniconda3/envs/cudaq/lib/python3.11/site-packages/cudaq/mlir/_mlir_libs/../../../targets/mapping/iqm/Adonis.txt')},delay-measurements,regtomem),iqm-gate-set-mapping
python: /llvm-project/mlir/lib/IR/PatternMatch.cpp:276: virtual void mlir::RewriterBase::eraseOp(mlir::Operation*): Assertion `op->use_empty() && "expected 'op' to have no uses"' failed.
Aborted

Expected behavior

successful compilation and execution

Is this a regression? If it is, put the last known working version (or commit) here.

Unknown

Environment

• CUDA Quantum version: 0.8.0
• Python version: Python 3.10.12
• C++ compiler: g++ (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0
• Operating system: Ubuntu 22.04.3 LTS (Jammy Jellyfish)

Suggestions

No response

[ColemanCollins]

additional context: I believe this to be unique to the uccsd kernel because other simple examples like the below run successfully

import cudaq
cudaq.set_target('ionq', emulate=True)

repro_kernel = cudaq.make_kernel()
repro_qubits = repro_kernel.qalloc(2)

repro_kernel.h(repro_qubits[0])
repro_kernel.cx(repro_qubits[0], repro_qubits[1])

repro_meas = cudaq.sample(repro_kernel, shots_count=100)
print(repro_meas)

[zohimchandani]

Cleaning up the code snippet a little from above:

import cudaq

num_qubits = 4
num_electrons = 2
thetas = [1,2,3]

@cudaq.kernel
def kernel(num_qubits: int, num_electrons:int, thetas:list[float]):
    
    qubits = cudaq.qvector(num_qubits)
    
    for i in range(num_electrons):
        x(qubits[i])
        
    cudaq.kernels.uccsd(qubits, thetas, num_electrons, num_qubits)
    
# cudaq.set_target('qpp-cpu')   
# cudaq.set_target('nvidia')

cudaq.set_target('ionq', emulate="true")
#cudaq.set_target('iqm', emulate=True, **{"qpu-architecture": "Adonis"})

results = cudaq.sample(kernel, num_qubits, num_electrons, thetas, shots_count=100)

print(results)

It works fine for the cpu and nvidia targets however the uccsd line throws the following error for the hardware targets:

python3: /root/.llvm-project/mlir/lib/IR/PatternMatch.cpp:276: virtual void mlir::RewriterBase::eraseOp(mlir::Operation*): Assertion `op->use_empty() && "expected 'op' to have no uses"' failed.
Aborted (core dumped)

[schweitzpgi]

My bad. I misread "uncomment".

Both the original code and Zohim's modified code have issues.

...
error: 'cc.loop' op not a constant upper bound loop
error: 'cc.loop' op not a constant upper bound loop
error: 'cc.loop' op not a constant upper bound loop
error: 'cc.loop' op loop bounds exceed iteration threshold
error: 'cc.loop' op not a constant upper bound loop
error: 'cc.loop' op not a constant upper bound loop
error: 'cc.loop' op not a constant upper bound loop
error: 'cc.loop' op loop bounds exceed iteration threshold
error: 'cc.loop' op not a constant upper bound loop
error: 'cc.loop' op not a constant upper bound loop
...