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[DAGCircuit Oxidation] Port DAGCircuit to Rust #12550

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merged 70 commits into from
Aug 23, 2024

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@kevinhartman kevinhartman commented Jun 11, 2024

Summary

Ports DAGCircuit itself to Rust. The primary benefit to doing this comes from migrating from Rustworkx's PyDiGraph PyO3 to a native Rust petgraph graph type, which can be accessed directly by Rust-based transpiler passes in the future (much faster). We should also pick up memory savings since our DAG's graph no longer stores DAGNode instances, and instead stores a lighter enum NodeType, which simply contains a PackedInstruction.

Status

Currently, the foundational stuff is in place, namely adding and removing bits/wires, registers, etc. along with conversion between DAGNode used by the Python API and the Rust struct NodeType, used for graph storage.

Remaining work includes

  • Port remaining DAGCircuit methods (I have stubbed any methods not yet implemented using todo()!).
  • Upgrade Rustworkx version (or point at main) to pick up any new rustworkx-core functionality needed to support the above.
  • Delete dagcircuit.py and wire-up the DAGCircuit Rust pyclass in its place (easy).
  • Rebase onto Add infrastructure for gates, instruction, and operations in Rust #12459 once it merges, which will involve potentially a lot of changes to use the native Operation it introduces.
  • Get existing Python testing to pass.
  • Clean up struct naming, fix warnings.
  • Performance profiling and tuning.
  • Memory profiling and tuning.

Open questions

  • Should we port BitLocations to Rust and make its management part of the Rust BitData struct?

Details and comments

Internally, the new Rust-based DAGCircuit uses a petgraph::StableGraph with node weights of type NodeType and edge weights of type Wire. The NodeType enum contains variants for QubitIn, QubitOut, ClbitIn, ClbitOut, and Operation, which should save us from all of the isinstance checking previously needed when working with DAGNode Python instances. The Wire enum contains variants Qubit and Clbit.

API access from Python-space is (still) done in terms of DAGNode instances to remain API compatible with the Python implementation. However, internally, we convert to and deal in terms of NodeType. When the user requests a particular node via lookup or iteration, we inflate an ephemeral DAGNode based on the internal NodeType and give them that. This is very similar to what we've done in #10827 when porting CircuitData to Rust.

For the future

Eventually, we should consider having a separate DAGCircuit that doesn't depend on PyO3 (i.e. a purely-Rust API), and generalize a lot of what is ported here to that, making this just a slim PyO3 wrapper around it. This may be possible in the very near future, or may even be possible by the time this PR is ready for merge. The plan is to revisit that separately, since more moving parts are on their way to Rust as we speak, and the thinking is we'll need more pieces to settle before we can design a sound Rust API, anyway.

@1ucian0 1ucian0 added the Rust This PR or issue is related to Rust code in the repository label Jun 12, 2024
@mtreinish mtreinish added performance mod: transpiler Issues and PRs related to Transpiler priority: high labels Jun 13, 2024
@mtreinish mtreinish added this to the 1.2.0 milestone Jun 13, 2024
mtreinish added a commit to mtreinish/qiskit-core that referenced this pull request Jun 24, 2024
This commit moves to using rust gates for the Optimize1QGatesDecomposition
transpiler pass. It takes in a sequence of runs (which are a list of
DAGOpNodes) from the python side of the transpiler pass which are
generated from DAGCircuit.collect_1q_runs() (which in the future should
be moved to rust after Qiskit#12550 merges). The rust portion of the pass now
iterates over each run, performs the matrix multiplication to compute the
unitary of the run, then synthesizes that unitary, computes the
estimated error of the circuit synthesis and returns a tuple of the
circuit sequence in terms of rust StandardGate enums. The python portion
of the code then takes those sequences and does inplace substitution of
each run with the sequence returned from rust.

Once Qiskit#12550 merges we should be able to move the input collect_1q_runs()
call and perform the output node substitions in rust making the full
pass execute in the rust domain without any python interaction.

Additionally, the OneQubitEulerDecomposer class is updated to use
rust for circuit generation instead of doing this python side. The
internal changes done to use rust gates in the transpiler pass meant we
were half way to this already by emitting rust StandardGates instead of
python gate objects. The dag handling is still done in Python however
until Qiskit#12550 merges.

This also includes an implementation of the r gate, I temporarily added
this to unblock this effort as it was the only gate missing needed to
complete this. We can rebase this if a standalone implementation of the
gate merges before this.
github-merge-queue bot pushed a commit that referenced this pull request Jul 3, 2024
* Use rust gates for Optimize1QGatesDecomposition

This commit moves to using rust gates for the Optimize1QGatesDecomposition
transpiler pass. It takes in a sequence of runs (which are a list of
DAGOpNodes) from the python side of the transpiler pass which are
generated from DAGCircuit.collect_1q_runs() (which in the future should
be moved to rust after #12550 merges). The rust portion of the pass now
iterates over each run, performs the matrix multiplication to compute the
unitary of the run, then synthesizes that unitary, computes the
estimated error of the circuit synthesis and returns a tuple of the
circuit sequence in terms of rust StandardGate enums. The python portion
of the code then takes those sequences and does inplace substitution of
each run with the sequence returned from rust.

Once #12550 merges we should be able to move the input collect_1q_runs()
call and perform the output node substitions in rust making the full
pass execute in the rust domain without any python interaction.

Additionally, the OneQubitEulerDecomposer class is updated to use
rust for circuit generation instead of doing this python side. The
internal changes done to use rust gates in the transpiler pass meant we
were half way to this already by emitting rust StandardGates instead of
python gate objects. The dag handling is still done in Python however
until #12550 merges.

This also includes an implementation of the r gate, I temporarily added
this to unblock this effort as it was the only gate missing needed to
complete this. We can rebase this if a standalone implementation of the
gate merges before this.

* Cache target decompositions for each qubit

Previously this PR was re-computing the target bases to synthesize with
for each run found in the circuit. But in cases where there were
multiple runs repeated on a qubit this was unecessary work. Prior to
moving this code to rust there was already caching code to make this
optimization, but the rust path short circuited around this. This commit
fixes this so we're caching the target bases for each qubit and only
computing it once.

* Optimize rust implementation slightly

* Avoid extra allocations by inlining matrix multiplication

* Remove unnecessary comment

* Remove stray code block

* Add import path for rust gate

* Use rust gate in circuit constructor

* Remove duplicated op_name getter and just use existing name getter

* Apply suggestions from code review

Co-authored-by: John Lapeyre <jlapeyre@users.noreply.github.com>

* Simplify construction of target_basis_vec

* Fix rebase issue

* Update crates/accelerate/src/euler_one_qubit_decomposer.rs

Co-authored-by: John Lapeyre <jlapeyre@users.noreply.github.com>

* Update crates/accelerate/src/euler_one_qubit_decomposer.rs

---------

Co-authored-by: John Lapeyre <jlapeyre@users.noreply.github.com>
@mtreinish mtreinish modified the milestones: 1.2.0, 1.3.0 Jul 15, 2024
Procatv pushed a commit to Procatv/qiskit-terra-catherines that referenced this pull request Aug 1, 2024
* Use rust gates for Optimize1QGatesDecomposition

This commit moves to using rust gates for the Optimize1QGatesDecomposition
transpiler pass. It takes in a sequence of runs (which are a list of
DAGOpNodes) from the python side of the transpiler pass which are
generated from DAGCircuit.collect_1q_runs() (which in the future should
be moved to rust after Qiskit#12550 merges). The rust portion of the pass now
iterates over each run, performs the matrix multiplication to compute the
unitary of the run, then synthesizes that unitary, computes the
estimated error of the circuit synthesis and returns a tuple of the
circuit sequence in terms of rust StandardGate enums. The python portion
of the code then takes those sequences and does inplace substitution of
each run with the sequence returned from rust.

Once Qiskit#12550 merges we should be able to move the input collect_1q_runs()
call and perform the output node substitions in rust making the full
pass execute in the rust domain without any python interaction.

Additionally, the OneQubitEulerDecomposer class is updated to use
rust for circuit generation instead of doing this python side. The
internal changes done to use rust gates in the transpiler pass meant we
were half way to this already by emitting rust StandardGates instead of
python gate objects. The dag handling is still done in Python however
until Qiskit#12550 merges.

This also includes an implementation of the r gate, I temporarily added
this to unblock this effort as it was the only gate missing needed to
complete this. We can rebase this if a standalone implementation of the
gate merges before this.

* Cache target decompositions for each qubit

Previously this PR was re-computing the target bases to synthesize with
for each run found in the circuit. But in cases where there were
multiple runs repeated on a qubit this was unecessary work. Prior to
moving this code to rust there was already caching code to make this
optimization, but the rust path short circuited around this. This commit
fixes this so we're caching the target bases for each qubit and only
computing it once.

* Optimize rust implementation slightly

* Avoid extra allocations by inlining matrix multiplication

* Remove unnecessary comment

* Remove stray code block

* Add import path for rust gate

* Use rust gate in circuit constructor

* Remove duplicated op_name getter and just use existing name getter

* Apply suggestions from code review

Co-authored-by: John Lapeyre <jlapeyre@users.noreply.github.com>

* Simplify construction of target_basis_vec

* Fix rebase issue

* Update crates/accelerate/src/euler_one_qubit_decomposer.rs

Co-authored-by: John Lapeyre <jlapeyre@users.noreply.github.com>

* Update crates/accelerate/src/euler_one_qubit_decomposer.rs

---------

Co-authored-by: John Lapeyre <jlapeyre@users.noreply.github.com>
@mtreinish mtreinish modified the milestones: 1.3.0, 1.3 beta Aug 8, 2024
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coveralls commented Aug 10, 2024

Pull Request Test Coverage Report for Build 10528140970

Details

  • 4879 of 5802 (84.09%) changed or added relevant lines in 39 files are covered.
  • 46 unchanged lines in 9 files lost coverage.
  • Overall coverage decreased (-0.7%) to 88.859%

Changes Missing Coverage Covered Lines Changed/Added Lines %
crates/circuit/src/interner.rs 10 11 90.91%
crates/circuit/src/circuit_data.rs 21 23 91.3%
crates/circuit/src/circuit_instruction.rs 3 9 33.33%
crates/circuit/src/operations.rs 10 17 58.82%
crates/circuit/src/packed_instruction.rs 65 72 90.28%
qiskit/visualization/dag_visualization.py 5 20 25.0%
crates/circuit/src/dag_node.rs 167 193 86.53%
crates/circuit/src/dot_utils.rs 0 68 0.0%
crates/circuit/src/rustworkx_core_vnext.rs 598 917 65.21%
crates/circuit/src/dag_circuit.rs 3900 4372 89.2%
Files with Coverage Reduction New Missed Lines %
crates/circuit/src/interner.rs 1 74.07%
qiskit/circuit/instruction.py 1 95.27%
qiskit/dagcircuit/dagnode.py 1 85.37%
crates/circuit/src/circuit_instruction.rs 4 88.5%
qiskit/dagcircuit/dagdependency_v2.py 5 67.62%
crates/qasm2/src/parse.rs 6 96.69%
crates/circuit/src/dag_node.rs 7 83.61%
crates/qasm2/src/lex.rs 7 91.73%
crates/circuit/src/operations.rs 14 88.19%
Totals Coverage Status
Change from base Build 10525107270: -0.7%
Covered Lines: 40166
Relevant Lines: 45202

💛 - Coveralls

kevinhartman and others added 2 commits August 12, 2024 07:27
This commit migrates the entirety of the `DAGCircuit` class to Rust. It
fully replaces the Python version of the class. The primary advantage
of this migration is moving from a Python space rustworkx directed graph
representation to a Rust space petgraph (the upstream library for
rustworkx) directed graph. Moving the graph data structure to rust
enables us to directly interact with the DAG directly from transpiler
passes in Rust in the future. This will enable a significant speed-up in
those transpiler passes. Additionally, this should also improve the
memory footprint as the DAGCircuit no longer stores `DAGNode`
instances, and instead stores a lighter enum NodeType, which simply
contains a `PackedInstruction` or the wire objects directly.

Internally, the new Rust-based `DAGCircuit` uses a `petgraph::StableGraph`
with node weights of type `NodeType` and edge weights of type `Wire`. The
NodeType enum contains variants for `QubitIn`, `QubitOut`, `ClbitIn`,
`ClbitOut`, and `Operation`, which should save us from all of the
`isinstance` checking previously needed when working with `DAGNode` Python
instances. The `Wire` enum contains variants `Qubit`, `Clbit`, and `Var`.

As the full Qiskit data model is not rust-native at this point while
all the class code in the `DAGCircuit` exists in Rust now, there are
still sections that rely on Python or actively run Python code via Rust
to function. These typically involve anything that uses `condition`,
control flow, classical vars, calibrations, bit/register manipulation,
etc. In the future as we either migrate this functionality to Rust or
deprecate and remove it this can be updated in place to avoid the use
of Python.

API access from Python-space remains in terms of `DAGNode` instances to
maintain API compatibility with the Python implementation. However,
internally, we convert to and deal in terms of NodeType. When the user
requests a particular node via lookup or iteration, we inflate an ephemeral
`DAGNode` based on the internal `NodeType` and give them that. This is very
similar to what was done in Qiskit#10827 when porting CircuitData to Rust.

As part of this porting there are a few small differences to keep in
mind with the new Rust implementation of DAGCircuit. The first is that
the topological ordering is slightly different with the new DAGCircuit.
Previously, the Python version of `DAGCircuit` using a lexicographical
topological sort key which was basically `"0,1,0,2"` where the first
`0,1` are qargs on qubit indices `0,1` for nodes and `0,2` are cargs
on clbit indices `0,2`. However, the sort key has now changed to be
`(&[Qubit(0), Qubit(1)], &[Clbit(0), Clbit(2)])` in rust in this case
which for the most part should behave identically, but there are some
edge cases that will appear where the sort order is different. It will
always be a valid topological ordering as the lexicographical key is
used as a tie breaker when generating a topological sort. But if you're
relaying on the exact same sort order there will be differences after
this PR. The second is that a lot of undocumented functionality in the
DAGCircuit which previously worked because of Python's implicit support
for interacting with data structures is no longer functional. For
example, previously the `DAGCircuit.qubits` list could be set directly
(as the circuit visualizers previously did), but this was never
documented as supported (and would corrupt the DAGCircuit). Any
functionality like this we'd have to explicit include in the Rust
implementation and as they were not included in the documented public
API this PR opted to remove the vast majority of this type of
functionality.

The last related thing might require future work to mitigate is that
this PR breaks the linkage between `DAGNode` and the underlying
`DAGCirucit` object. In the Python implementation the `DAGNode` objects
were stored directly in the `DAGCircuit` and when an API method returned
a `DAGNode` from the DAG it was a shared reference to the underlying
object in the `DAGCircuit`. This meant if you mutated the `DAGNode` it
would be reflected in the `DAGCircuit`. This was not always a sound
usage of the API as the `DAGCircuit` was implicitly caching many
attributes of the DAG and you should always be using the `DAGCircuit`
API to mutate any nodes to prevent any corruption of the `DAGCircuit`.
However, now as the underlying data store for nodes in the DAG are
no longer the python space objects returned by `DAGCircuit` methods
mutating a `DAGNode` will not make any change in the underlying
`DAGCircuit`. This can come as quite the surprise at first, especially
if you were relying on this side effect, even if it was unsound.

It's also worth noting that 2 large pieces of functionality from
rustworkx are included in this PR. These are the new files
`rustworkx_core_vnext` and `dot_utils` which are rustworkx's VF2
implementation and its dot file generation. As there was not a rust
interface exposed for this functionality from rustworkx-core there was
no way to use these functions in rustworkx. Until these interfaces
added to rustworkx-core in future releases we'll have to keep these
local copies. The vf2 implementation is in progress in
Qiskit/rustworkx#1235, but `dot_utils` might make sense to keep around
longer term as it is slightly modified from the upstream rustworkx
implementation to directly interface with `DAGCircuit` instead of a
generic graph.

Co-authored-by: Matthew Treinish <mtreinish@kortar.org>
Co-authored-by: Raynel Sanchez <87539502+raynelfss@users.noreply.github.com>
Co-authored-by: Elena Peña Tapia <57907331+ElePT@users.noreply.github.com>
Co-authored-by: Alexander Ivrii <alexi@il.ibm.com>
Co-authored-by: Eli Arbel <46826214+eliarbel@users.noreply.github.com>
Co-authored-by: John Lapeyre <jlapeyre@users.noreply.github.com>
Co-authored-by: Jake Lishman <jake.lishman@ibm.com>
Right now there is a bug in the matplotlib circuit visualizer likely
caused by the new `__eq__` implementation for `DAGOpNode` that didn't
exist before were some gates are missing from the visualization. In the
interest of unblocking this PR this commit updates the references for
these cases temporarily until this issue is fixed.
@mtreinish mtreinish marked this pull request as ready for review August 12, 2024 11:40
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  • @enavarro51
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  • @kevinhartman
  • @levbishop
  • @mtreinish
  • @nkanazawa1989

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mtreinish commented Aug 12, 2024

I've marked this as ready for review as it's finally at a point where I think we can consider this for merging. I've squashed the 281 commits, with mostly 1 line commit messages, into one giant commit that has a detailed commit message and I don't think there is any big blocker anymore. It's still a bit rough around the edges in places and I think we'll need to do some performance tuning on it as unit tests seem to execute slightly slower with this. The only known issue that is a potential blocker is 1e4e6f3 which is I expect is a similar failure mode to what was fixed in 41be5f1. But since this PR is so high priority and large I opted to just update the references and we can track that as an issue to fix before release. But if we do manage to find a fix as part of this we can just revert 1e4e6f3 which is why I left it as a separate commit.

This commit migrates the qubit_io_map and clbit_io_map to go from a type
of `IndexMap<Qubit, [NodeIndex; 2], RandomState>` to
`Vec<[NodeIndex; 2]>`. Our qubit indices (represented by the `Qubit`
type) must be a contiguous set for the circuit to be valid, and using an
`IndexMap` for these mappings of bit to input and output nodes only
really improved performance in the removal case, but at the cost of
additional runtime overhead for accessing the data. Since removals are
rare and also inefficient because it needs to reindex the entire dag
already we should instead optimize for the accessing the data. Since we
have contiguous indices using a Vec is a natural structure to represent
this mapping.
At some point during the development of this PR the function signatures
between `add_qubits()` and `add_clbits()` diverged between taking a
`Vec<Bound<PyAny>>` and `&Bound<PySequence>`. In general they're are
comprable but since we are going to be working with a `Vec<>` in the
function body this is a better choice to let PyO3 worry about the
conversion for us. Additionally, this is a more natural signature for
rust consumption. This commit just updates `add_clbits()` to use a Vec
too.
mtreinish added a commit to mtreinish/qiskit-core that referenced this pull request Aug 22, 2024
This commit builds off of Qiskit#12550 and the other data model in Rust
infrastructure and migrates the Optimize1qGatesDecomposition pass to
operate fully in Rust. The full path of the transpiler pass now never
leaves rust until it has finished modifying the DAGCircuit. There is
still some python interaction necessary to handle parts of the data
model that are still in Python, mainly calibrations and parameter
expressions (for global phase). But otherwise the entirety of the pass
operates in rust now.

This is just a first pass at the migration here, it moves the pass to be
a single for loop in rust. The next steps here are to look at operating
the pass in parallel. There is no data dependency between the
optimizations being done by the pass so we should be able to the
throughput of the pass by leveraging multithreading to handle each run
in parallel. This commit does not attempt this though, because of the
Python dependency and also the data structures around gates and the
dag aren't really setup for multithreading yet and there likely will
need to be some work to support that (this pass is a good candidate to
work through the bugs on that).

Part of Qiskit#12208
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I think the add vars methods should be exposed to at least the rust crate. Because we kind of need these if we were to implement converters in Rust.

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Thanks everyone for all the work that went into this.

I think we're now in the right position to merge this, and we can all get to work on the transpiler passes, and some of the follow-up work that we've identified over the course of the last couple of months.

@jakelishman jakelishman added this pull request to the merge queue Aug 23, 2024
Merged via the queue into Qiskit:main with commit d3040a0 Aug 23, 2024
15 checks passed
mtreinish added a commit to mtreinish/qiskit-core that referenced this pull request Aug 23, 2024
This commit builds off of Qiskit#12550 and the other data model in Rust
infrastructure and migrates the Optimize1qGatesDecomposition pass to
operate fully in Rust. The full path of the transpiler pass now never
leaves rust until it has finished modifying the DAGCircuit. There is
still some python interaction necessary to handle parts of the data
model that are still in Python, mainly calibrations and parameter
expressions (for global phase). But otherwise the entirety of the pass
operates in rust now.

This is just a first pass at the migration here, it moves the pass to be
a single for loop in rust. The next steps here are to look at operating
the pass in parallel. There is no data dependency between the
optimizations being done by the pass so we should be able to the
throughput of the pass by leveraging multithreading to handle each run
in parallel. This commit does not attempt this though, because of the
Python dependency and also the data structures around gates and the
dag aren't really setup for multithreading yet and there likely will
need to be some work to support that (this pass is a good candidate to
work through the bugs on that).

Part of Qiskit#12208
github-merge-queue bot pushed a commit that referenced this pull request Aug 30, 2024
* Fully port Optimize1qGatesDecomposition to Rust

This commit builds off of #12550 and the other data model in Rust
infrastructure and migrates the Optimize1qGatesDecomposition pass to
operate fully in Rust. The full path of the transpiler pass now never
leaves rust until it has finished modifying the DAGCircuit. There is
still some python interaction necessary to handle parts of the data
model that are still in Python, mainly calibrations and parameter
expressions (for global phase). But otherwise the entirety of the pass
operates in rust now.

This is just a first pass at the migration here, it moves the pass to be
a single for loop in rust. The next steps here are to look at operating
the pass in parallel. There is no data dependency between the
optimizations being done by the pass so we should be able to the
throughput of the pass by leveraging multithreading to handle each run
in parallel. This commit does not attempt this though, because of the
Python dependency and also the data structures around gates and the
dag aren't really setup for multithreading yet and there likely will
need to be some work to support that (this pass is a good candidate to
work through the bugs on that).

Part of #12208

* Tweak control_flow_op_nodes() method to avoid dag traversal when not necessary

* Store target basis set without heap allocation

Since we only are storing 12 enum fields (which are a single byte) using
any heap allocated collection is completely overkill and will have more
overhead that storing a statically sized array for all 12 variants. This
commit adds a new struct that wraps a `[bool; 12]` to track which
basis are supported and an API for tracking this. This simplifies the
tracking of which qubit supports which EulerBasis, it also means other
internal users of the 1q decomposition have a simplified API for working
with the euler basis.

* Remove From trait for Qubit->PhysicalQubit conversion

* Fix merge conflict

* Use new DAGCircuit::has_control_flow() for control_flow_op_nodes() pymethod

* Move _basis_gates set creation to __init__

* Update releasenotes/notes/optimize-1q-gates-decomposition-ce111961b6782ee0.yaml

Co-authored-by: Elena Peña Tapia <57907331+ElePT@users.noreply.github.com>

---------

Co-authored-by: Elena Peña Tapia <57907331+ElePT@users.noreply.github.com>
github-merge-queue bot pushed a commit that referenced this pull request Sep 4, 2024
* init

* up

* lint

* .

* up

* before cache

* with cache

* correct

* cleaned up

* lint reno

* Update Cargo.lock

* .

* up

* .

* revert op

* .

* .

* .

* .

* Delete Cargo.lock

* .

* corrected string comparison

* removed Operator class from operation.rs

* .

* Apply suggestions from code review

Co-authored-by: Raynel Sanchez <87539502+raynelfss@users.noreply.github.com>

* comments from code review

* Port DAGCircuit to Rust

This commit migrates the entirety of the `DAGCircuit` class to Rust. It
fully replaces the Python version of the class. The primary advantage
of this migration is moving from a Python space rustworkx directed graph
representation to a Rust space petgraph (the upstream library for
rustworkx) directed graph. Moving the graph data structure to rust
enables us to directly interact with the DAG directly from transpiler
passes in Rust in the future. This will enable a significant speed-up in
those transpiler passes. Additionally, this should also improve the
memory footprint as the DAGCircuit no longer stores `DAGNode`
instances, and instead stores a lighter enum NodeType, which simply
contains a `PackedInstruction` or the wire objects directly.

Internally, the new Rust-based `DAGCircuit` uses a `petgraph::StableGraph`
with node weights of type `NodeType` and edge weights of type `Wire`. The
NodeType enum contains variants for `QubitIn`, `QubitOut`, `ClbitIn`,
`ClbitOut`, and `Operation`, which should save us from all of the
`isinstance` checking previously needed when working with `DAGNode` Python
instances. The `Wire` enum contains variants `Qubit`, `Clbit`, and `Var`.

As the full Qiskit data model is not rust-native at this point while
all the class code in the `DAGCircuit` exists in Rust now, there are
still sections that rely on Python or actively run Python code via Rust
to function. These typically involve anything that uses `condition`,
control flow, classical vars, calibrations, bit/register manipulation,
etc. In the future as we either migrate this functionality to Rust or
deprecate and remove it this can be updated in place to avoid the use
of Python.

API access from Python-space remains in terms of `DAGNode` instances to
maintain API compatibility with the Python implementation. However,
internally, we convert to and deal in terms of NodeType. When the user
requests a particular node via lookup or iteration, we inflate an ephemeral
`DAGNode` based on the internal `NodeType` and give them that. This is very
similar to what was done in #10827 when porting CircuitData to Rust.

As part of this porting there are a few small differences to keep in
mind with the new Rust implementation of DAGCircuit. The first is that
the topological ordering is slightly different with the new DAGCircuit.
Previously, the Python version of `DAGCircuit` using a lexicographical
topological sort key which was basically `"0,1,0,2"` where the first
`0,1` are qargs on qubit indices `0,1` for nodes and `0,2` are cargs
on clbit indices `0,2`. However, the sort key has now changed to be
`(&[Qubit(0), Qubit(1)], &[Clbit(0), Clbit(2)])` in rust in this case
which for the most part should behave identically, but there are some
edge cases that will appear where the sort order is different. It will
always be a valid topological ordering as the lexicographical key is
used as a tie breaker when generating a topological sort. But if you're
relaying on the exact same sort order there will be differences after
this PR. The second is that a lot of undocumented functionality in the
DAGCircuit which previously worked because of Python's implicit support
for interacting with data structures is no longer functional. For
example, previously the `DAGCircuit.qubits` list could be set directly
(as the circuit visualizers previously did), but this was never
documented as supported (and would corrupt the DAGCircuit). Any
functionality like this we'd have to explicit include in the Rust
implementation and as they were not included in the documented public
API this PR opted to remove the vast majority of this type of
functionality.

The last related thing might require future work to mitigate is that
this PR breaks the linkage between `DAGNode` and the underlying
`DAGCirucit` object. In the Python implementation the `DAGNode` objects
were stored directly in the `DAGCircuit` and when an API method returned
a `DAGNode` from the DAG it was a shared reference to the underlying
object in the `DAGCircuit`. This meant if you mutated the `DAGNode` it
would be reflected in the `DAGCircuit`. This was not always a sound
usage of the API as the `DAGCircuit` was implicitly caching many
attributes of the DAG and you should always be using the `DAGCircuit`
API to mutate any nodes to prevent any corruption of the `DAGCircuit`.
However, now as the underlying data store for nodes in the DAG are
no longer the python space objects returned by `DAGCircuit` methods
mutating a `DAGNode` will not make any change in the underlying
`DAGCircuit`. This can come as quite the surprise at first, especially
if you were relying on this side effect, even if it was unsound.

It's also worth noting that 2 large pieces of functionality from
rustworkx are included in this PR. These are the new files
`rustworkx_core_vnext` and `dot_utils` which are rustworkx's VF2
implementation and its dot file generation. As there was not a rust
interface exposed for this functionality from rustworkx-core there was
no way to use these functions in rustworkx. Until these interfaces
added to rustworkx-core in future releases we'll have to keep these
local copies. The vf2 implementation is in progress in
Qiskit/rustworkx#1235, but `dot_utils` might make sense to keep around
longer term as it is slightly modified from the upstream rustworkx
implementation to directly interface with `DAGCircuit` instead of a
generic graph.

Co-authored-by: Matthew Treinish <mtreinish@kortar.org>
Co-authored-by: Raynel Sanchez <87539502+raynelfss@users.noreply.github.com>
Co-authored-by: Elena Peña Tapia <57907331+ElePT@users.noreply.github.com>
Co-authored-by: Alexander Ivrii <alexi@il.ibm.com>
Co-authored-by: Eli Arbel <46826214+eliarbel@users.noreply.github.com>
Co-authored-by: John Lapeyre <jlapeyre@users.noreply.github.com>
Co-authored-by: Jake Lishman <jake.lishman@ibm.com>

* Update visual mpl circuit drawer references

Right now there is a bug in the matplotlib circuit visualizer likely
caused by the new `__eq__` implementation for `DAGOpNode` that didn't
exist before were some gates are missing from the visualization. In the
interest of unblocking this PR this commit updates the references for
these cases temporarily until this issue is fixed.

* Ensure DAGNode.sort_key is always a string

Previously the sort_key attribute of the Python space DAGCircuit was
incorrectly being set to `None` for rust generated node objects. This
was done as for the default path the sort key is determined from the
rust domain's representation of qubits and there is no analogous data in
the Python object. However, this was indavertandly a breaking API change
as sort_key is expected to always be a string. This commit adds a
default string to use for all node types so that we always have a
reasonable value that matches the typing of the class. A future step is
likely to add back the `dag` kwarg to the node types and generate the
string on the fly from the rust space data.

* Make Python argument first in Param::eq and Param::is_close

The standard function signature convention for functions that take a
`py: Python` argument is to make the Python argument the first (or
second after `&self`). The `Param::eq` and `Param::is_close` methods
were not following this convention and had `py` as a later argument in
the signature. This commit corrects the oversight.

* Fix merge conflict with #12943

With the recent merge with main we pulled in #12943 which conflicted
with the rust space API changes made in this PR branch. This commit
updates the usage to conform with the new interface introduced in this
PR.

* Add release notes and test for invalid args on apply methods

This commit adds several release notes to document this change. This
includes a feature note to describe the high level change and the user
facing benefit (mainly reduced memory consumption for DAGCircuits),
two upgrade notes to document the differences with shared references
caused by the new data structure, and a fix note documenting the fix
for how qargs and cargs are handled on `.apply_operation_back()` and
`.apply_operation_front()`. Along with the fix note a new unit test is
added to serve as a regression test so that we don't accidentally allow
adding cargs as qargs and vice versa in the future.

* Restore `inplace` argument functionality for substitute_node()

This commit restores the functionality of the `inplace` argument for
`substitute_node()` and restores the tests validating the object
identity when using the flag. This flag was originally excluded from
the implementation because the Rust representation of the dag is not
a shared reference with Python space and the flag doesn't really mean
the same thing as there is always a second copy of the data for Python
space now. The implementation here is cheating slighty as we're passed
in the DAG node by reference it relies on that reference to update the
input node at the same time we update the dag. Unlike the previous
Python implementation where we were updating the node in place and the
`inplace` argument was slightly faster because everything was done by
reference. The rust space data is still a compressed copy of the data
we return to Python so the `inplace` flag will be slightly more
inefficient as we need to copy to update the Python space representation
in addition to the rust version.

* Revert needless dict() cast on metadata in dag_to_circuit()

This commit removes an unecessary `dict()` cast on the `dag.metadata`
when setting it on `QuantumCircuit.metadata` in
`qiskit.converters.dag_to_circuit()`. This slipped in at some point
during the development of this PR and it's not clear why, but it isn't
needed so this removes it.

* Add code comment for DAGOpNode.__eq__ parameter checking

This commit adds a small inline code comment to make it clear why we
skip parameter comparisons in DAGOpNode.__eq__ for python ops. It might
not be clear why the value is hard coded to `true` in this case, as this
check is done via Python so we don't need to duplicate it in rust space.

* Raise a ValueError on DAGNode creation with invalid index

This commit adds error checking to the DAGNode constructor to raise a
PyValueError if the input index is not valid (any index < -1).
Previously this would have panicked instead of raising a user catchable
error.

* Use macro argument to set python getter/setter name

This commit updates the function names for `get__node_id` and
`set__node_id` method to use a name that clippy is happy with and
leverage the pyo3 macros to set the python space name correctly instead
of using the implicit naming rules.

* Remove Ord and PartialOrd derives from interner::Index

The Ord and PartialOrd traits were originally added to the Index struct
so they could be used for the sort key in lexicographical topological
sorting. However, that approach was abandonded during the development of
this PR and instead the expanded Qubit and Clbit indices were used
instead. This left the ordering traits as unnecessary on Index and
potentially misleading. This commit just opts to remove them as they're
not needed anymore.

* Fix missing nodes in matplotlib drawer.

Previously, the change in equality for DAGNodes was causing nodes
to clobber eachother in the matplotlib drawer's tracking data
structures when used as keys to maps.

To fix this, we ensure that all nodes have a unique ID across
layers before constructing the matplotlib drawer. They actually
of course _do_ in the original DAG, but we don't really care
what the original IDs are, so we just make them up.

Writing to _node_id on a DAGNode may seem odd, but it exists
in the old Python API (prior to being ported to Rust) and
doesn't actually mutate the DAG at all since DAGNodes are
ephemeral.

* Revert "Update visual mpl circuit drawer references"

With the previous commit the bug in the matplotlib drawer causing the
images to diverge should be fixed. This commit reverts the change to the
reference images as there should be no difference now.

This reverts commit 1e4e6f3.

* Update visual mpl circuit drawer references for control flow circuits

The earlier commit that "fixed" the drawers corrected the visualization
to match expectations in most cases. However after restoring the
references to what's on main several comparison tests with control flow
in the circuit were still failing. The failure mode looks similar to the
other cases, but across control flow blocks instead of at the circuit
level. This commit temporarily updates the references of these to the
state of what is generated currently to unblock CI. If/when we have a
fix this commit can be reverted.

* Apply suggestions from code review

Co-authored-by: Raynel Sanchez <87539502+raynelfss@users.noreply.github.com>

* code review

* Fix edge cases in DAGOpNode.__eq__

This commit fixes a couple of edge cases in DAGOpNode.__eq__ method
around the python interaction for the method. The first is that in
the case where we had python object parameter types for the gates we
weren't comparing them at all. This is fixed so we use python object
equality for the params in this case. Then we were dropping the error
handling in the case of using python for equality, this fixes it to
return the error to users if the equality check fails. Finally a comment
is added to explain the expected use case for `DAGOpNode.__eq__` and why
parameter checking is more strict than elsewhere.

* Remove Param::add() for global phase addition

This commit removes the Param::add() method and instead adds a local
private function to the `dag_circuit` module for doing global phase
addition. Previously the `Param::add()` method was used solely for
adding global phase in `DAGCircuit` and it took some shortcuts knowing
that context. This made the method implementation ill suited as a
general implementation.

* More complete fix for matplotlib drawer.

* Revert "Update visual mpl circuit drawer references for control flow circuits"

This reverts commit 9a6f953.

* Unify rayon versions in workspace

* Remove unused _GLOBAL_NID.

* Use global monotonic ID counter for ids in drawer

The fundamental issue with matplotlib visualizations of control flow is
that locally in the control flow block the nodes look the same but are
stored in an outer circuit dictionary. If the gates are the same and on
the same qubits and happen to have the same node id inside the different
control flow blocks the drawer would think it's already drawn the node
and skip it incorrectly. The previous fix for this didn't go far enough
because it wasn't accounting for the recursive execution of the drawer
for inner blocks (it also didn't account for LayerSpoolers of the same
length).

* Remove unused BitData iterator stuff.

* Fully port Optimize1qGatesDecomposition to Rust

This commit builds off of #12550 and the other data model in Rust
infrastructure and migrates the Optimize1qGatesDecomposition pass to
operate fully in Rust. The full path of the transpiler pass now never
leaves rust until it has finished modifying the DAGCircuit. There is
still some python interaction necessary to handle parts of the data
model that are still in Python, mainly calibrations and parameter
expressions (for global phase). But otherwise the entirety of the pass
operates in rust now.

This is just a first pass at the migration here, it moves the pass to be
a single for loop in rust. The next steps here are to look at operating
the pass in parallel. There is no data dependency between the
optimizations being done by the pass so we should be able to the
throughput of the pass by leveraging multithreading to handle each run
in parallel. This commit does not attempt this though, because of the
Python dependency and also the data structures around gates and the
dag aren't really setup for multithreading yet and there likely will
need to be some work to support that (this pass is a good candidate to
work through the bugs on that).

Part of #12208

* remove with_gil in favor of passing python tokens as params

* Apply suggestions from code review

Co-authored-by: Raynel Sanchez <87539502+raynelfss@users.noreply.github.com>

* fmt

* python serialization

* deprecation

* Update commutation_checker.py

* heh

* init

* let Pytuple collect

* lint

* First set of comments

- use Qubit/Clbit
- more info on unsafe
- update reno
- use LazySet less
- use OperationRef, avoid CircuitInstruction creation

* Second part

- clippy
- no BigInt
- more comments

* Matrix speed & fix string sort

-- could not use op.name() directly since sorted differently than Python, hence it's back to BigInt

* have the Python implementation use Rust

* lint & tools

* remove unsafe blocks

* One more try to avoid segfaulty windows

-- if that doesn't work maybe revert the change the the Py CommChecker uses Rust

* Original version

Co-authored-by: Sebastian Brandhofer <148463728+sbrandhsn@users.noreply.github.com>

* Sync with updated CommutationChecker

todo: shouldn't make the qubits interner public

* Debug: disable cache

trying to figure out why the windows CI fails (after being unable to locally reproduce we're using CI with a reduced set of tests)

* ... second try

* Update crates/accelerate/src/commutation_checker.rs

Co-authored-by: Raynel Sanchez <87539502+raynelfss@users.noreply.github.com>

* Restore azure config

* Remove unused import

* Revert "Debug: disable cache"

This reverts commit c564b80.

* Don't overallocate cache

We were allocating a the cache hashmap with a capacity for max cache
size entries every time we instantiated a new CommutationChecker. The
max cache size is 1 million. This meant we were allocating 162MB
everytime CommutationChecker.__new__ was called, which includes each
time we instantiate it manually (which happens once on import), the
CommutationAnalysis pass gets instantiated (twice per preset pass
manager created with level 2 or 3), or a commutation checker instance is
pickle deserialized. This ends up causing a fairly large memory
regression and is the source of the CI failures on windows.

Co-authored-by: Jake Lishman <jake.lishman@ibm.com>

* Cleanup parameter key type to handle edge conditions better

This commit cleans up the ParameterKey type and usage to make it handle
edge conditions better. The first is that the type just doesn't do the
right thing for NaN, -0, or the infinities. Canonicalization is added
for hash on -0 and the only constructor of the newtype adds a runtime
guard against NaN and inifinity (positive or negative) to avoid that
issue. The approach only makes sense as the cache is really there to
guard us against unnecessary re-computing when we reiterate over the
circuit > 1 time and nothing has changed for gates. Otherwise comparing
floats like done in this PR does would not be a sound or an effective
approach.

* Remove unnecessary cache hit rate tracking

* Undo test assertion changes

* Undo unrelated test changes

* Undo pending deprecation and unify commutation classes

This commit removes the pending deprecation decorator from the python
class definition as the Python class just internally is using the rust
implementation now. This also removes directly using the rust
implementation for the standard commutation library global as using the
python class is exactly the same now.

We can revisit if there is anything we want to deprecate and remove in
2.0 in a follow up PR. Personally, I think the cache management methods
are all we really want to remove as the cache should be an internal
implementation detail and not part of the public interface.

* Undo gha config changes

* Make serialization explicit

This commit makes the pickling of cache entries explicit. Previously it
was relying on conversion traits which hid some of the complexity but
this uses a pair of conversion functions instead.

* Remove stray SAFETY comment

* Remove ddt usage from the tests

Now that the python commutation checker and the rust commutation checker
are the same thing the ddt parameterization of the commutation checker
tests was unecessary duplication. This commit removes the ddt usage to
restore having a single run of all the tests.

* Update release note

* Fix CommutationChecker class import

* Remove invalid test assertion for no longer public attribute

* Ray's review comments

Co-authored-by: Raynel Sanchez <raynelfss@hotmail.com>

* Handle ``atol/rtol``, more error propagation

* update to latest changes in commchecker

* fix merge conflict remnants

* re-use expensive quantities

such as the relative placement and the parameter hash

* add missing header

* gentler error handling

* review comments & more docs

* Use vec over IndexSet + clippy

- vec<vec> is slightly faster than vec<indexset>
- add custom types to satisfies clippy's complex type complaint
- don't handle Clbit/Var

* Simplify python class construction

Since this PR was first written the split between the python side and
rust side of the CommutationChecker class has changed so that there are
no longer separate classes anymore. The implementations are unified and
the python space class just wraps an inner rust object. However, the
construction of the CommutationAnalysis pass was still written assuming
there was the possibility to get either a rust or Python object. This
commit fixes this and the type change on the `comm_checker` attribute by
removing the unnecessary logic.

---------

Co-authored-by: Raynel Sanchez <87539502+raynelfss@users.noreply.github.com>
Co-authored-by: Kevin Hartman <kevin@hart.mn>
Co-authored-by: Matthew Treinish <mtreinish@kortar.org>
Co-authored-by: Elena Peña Tapia <57907331+ElePT@users.noreply.github.com>
Co-authored-by: Alexander Ivrii <alexi@il.ibm.com>
Co-authored-by: Eli Arbel <46826214+eliarbel@users.noreply.github.com>
Co-authored-by: John Lapeyre <jlapeyre@users.noreply.github.com>
Co-authored-by: Jake Lishman <jake.lishman@ibm.com>
Co-authored-by: Julien Gacon <jules.gacon@googlemail.com>
Co-authored-by: Raynel Sanchez <raynelfss@hotmail.com>
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