QASM2 to squin #644

johnzl-777 · 2025-12-04T14:41:29Z

This is my implementation of #540 , there is one thing that I've held off on after talking with @weinbe58 that's a bit tricky: handling measurements. My understanding is we don't need it for now but in the future it will be relevant.

While 95% of qasm2 maps very nicely to existing squin infrastructure (with the exception of some of the less common 2 and 3 qubit gates I had to skip - unless we want to do some implicit conversion for them) you run into problems trying to map the qasm2 measurement semantics.

Take the following examples:

A user wants to measure out all the qubits to the entirety of the declared register. Your qasm2 looks something like this

qreg q[5]
creg c[5]
measure q -> c

You could potentially just have creg be an empty ilist and then when the measure happens produce the ilist of measurements - making sure that all subsequent references point to the new ilist. This seems acceptable but it gets tricky if a user wants to do something like

a user only wants to measure a single qubit and save that to a slot in the classical register. This looks like

qreg q[5]
creg c[5]
measure q[0] -> c[0]

Now the classical register somehow has to already be get_item-able which is tricky considering there's no notion of a fixed-length list. Things get even trickier if a user wants to save at a different index:

measure q[1] -> c[3]

P.S. The sub kernel rewrite seems "off" to me, I'm sure there must be a better way to do it but I'm not aware of what the proper API for it is 😅

codecov · 2025-12-04T14:44:43Z

Codecov Report

❌ Patch coverage is 98.52217% with 3 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...c/bloqade/squin/passes/qasm2_gate_func_to_squin.py	86.95%	3 Missing ⚠️

📢 Thoughts on this report? Let us know!

github-actions · 2025-12-04T14:45:02Z

☂️ Python Coverage

current status: ✅

Overall Coverage

Lines	Covered	Coverage	Threshold	Status
10759	9494	88%	0%	🟢

New Files

File	Coverage	Status
src/bloqade/squin/passes/_init_.py	100%	🟢
src/bloqade/squin/passes/qasm2_gate_func_to_squin.py	87%	🟢
src/bloqade/squin/passes/qasm2_to_squin.py	100%	🟢
src/bloqade/squin/rewrite/qasm2/_init_.py	100%	🟢
src/bloqade/squin/rewrite/qasm2/core_to_squin.py	100%	🟢
src/bloqade/squin/rewrite/qasm2/glob_parallel_to_squin.py	100%	🟢
src/bloqade/squin/rewrite/qasm2/id_to_squin.py	100%	🟢
src/bloqade/squin/rewrite/qasm2/noise_to_squin.py	100%	🟢
src/bloqade/squin/rewrite/qasm2/parametrized_uop_1q_to_squin.py	100%	🟢
src/bloqade/squin/rewrite/qasm2/uop_1q_to_squin.py	100%	🟢
src/bloqade/squin/rewrite/qasm2/uop_2q_to_squin.py	100%	🟢
TOTAL	99%	🟢

Modified Files

File	Coverage	Status
src/bloqade/qasm2/dialects/uop/stmts.py	100%	🟢
TOTAL	100%	🟢

updated for commit: aea7567 by action🐍

johnzl-777 · 2025-12-05T14:43:55Z

Used Callgraph pass after talking to Phil, I originally had a pretty funky rewrite rule to handle subkernels 😅

johnzl-777 · 2025-12-05T14:58:16Z

Latest round of feedback (from Phil): use dictionary style mapping (faster than pattern matching) + can use pre-existing QASM2 to py expr rewriterule.

Should also try to avoid multi-layer matching logic, easier to reason through/test smaller rules.

…lready exists

…round

david-pl

Overall looks good and the tests are quite extensive, which is great. I have some questions and small comments.

src/bloqade/squin/passes/qasm2_to_squin.py

david-pl · 2025-12-09T10:06:29Z

src/bloqade/squin/rewrite/qasm2/core_to_squin.py

+        else:
+            return RewriteResult()
+
+        new_stmt = func.Invoke(


I feel like you could just do this within the if above, since the args have to match the node type anyway.

something like

if isinstance(node, (core_stmts.QRegGet, core_stmts.QRegNew, core_stmts.Reset): node.replace_by(func.Invoke(node.args, callee = callees[type(note)) else: return RewriteResult()

david-pl · 2025-12-09T10:07:26Z

src/bloqade/squin/rewrite/qasm2/glob_parallel_to_squin.py

+
+    def rewrite_Statement(self, node: ir.Statement) -> RewriteResult:
+
+        if isinstance(node, glob.UGate):


Again, this seems a bit redundant: you might as well just assign squin_equivalent_stmt in each case here rather than using the map above.

The dictionary was something that @weinbe58 recommended, I could be doing the pattern wrong here but in cases where I do see a dictionary used it only turns out nice if the attribute you're accessing exits across all the statements.

Like for arithmetic operation conversion, you'll always have an lhs and rhs attribute. Here the number and kinds of attributes change.

I actually realize if I wanted to be clever I could add some strings to the values in the dictionary and then __getattribute__ things which would resolve the clunkiness at the expense of making things a little uglier.

Wish I could still do pattern matching but I'm told the performance would take a hit

you do not need to unpack the arguments, unless they do not match the signature of the standard library function in squin but I think we have been consistent on this front so you should not need to do this @johnzl-777 see my comment above.

src/bloqade/squin/rewrite/qasm2/noise_to_squin.py

david-pl · 2025-12-09T10:11:25Z

src/bloqade/squin/rewrite/qasm2/noise_to_squin.py

+            return RewriteResult()
+
+        squin_noise_stmt = NOISE_TO_SQUIN_MAP[type(node)]
+        invoke_stmt = func.Invoke(


If you know that you are going for the broadcast version, why not just rewrite to the statement directly instead of adding an invoke to the stdlib?

see the comment above

src/bloqade/squin/rewrite/qasm2/core_to_squin.py

weinbe58

Overall looks good I just have some small updates to the code to reduce the number of special cases.

In general you could wrap all the "easy" rewrites with statements that match the stdlib signature exactly into a single rewrite pass that using one master dictionary to map the statement to their equivalent stdlib function and then handle the special cases like U1 and U2 in a separate rewrite. as their own separate rewrites and that might be a bit cleaner then spreading out the rewrites over

src/bloqade/squin/passes/qasm2_to_squin.py

weinbe58 · 2025-12-11T14:30:38Z

src/bloqade/squin/rewrite/qasm2/core_to_squin.py

+        else:
+            return RewriteResult()
+
+        new_stmt = func.Invoke(


something like

if isinstance(node, (core_stmts.QRegGet, core_stmts.QRegNew, core_stmts.Reset): node.replace_by(func.Invoke(node.args, callee = callees[type(note)) else: return RewriteResult()

src/bloqade/squin/rewrite/qasm2/core_to_squin.py

weinbe58 · 2025-12-11T14:35:15Z

src/bloqade/squin/rewrite/qasm2/glob_parallel_to_squin.py

+
+    def rewrite_Statement(self, node: ir.Statement) -> RewriteResult:
+
+        if isinstance(node, glob.UGate):


you do not need to unpack the arguments, unless they do not match the signature of the standard library function in squin but I think we have been consistent on this front so you should not need to do this @johnzl-777 see my comment above.

weinbe58 · 2025-12-11T14:35:32Z

src/bloqade/squin/rewrite/qasm2/noise_to_squin.py

+            return RewriteResult()
+
+        squin_noise_stmt = NOISE_TO_SQUIN_MAP[type(node)]
+        invoke_stmt = func.Invoke(


see the comment above

weinbe58 · 2025-12-11T14:39:37Z

src/bloqade/squin/rewrite/qasm2/parametrized_uop_1q_to_squin.py

+        if isinstance(node, (uop_stmts.RX, uop_stmts.RY, uop_stmts.RZ)):
+            args = (node.theta, node.qarg)
+        elif isinstance(node, (uop_stmts.UGate)):
+            args = (node.theta, node.phi, node.lam, node.qarg)
+        elif isinstance(node, (uop_stmts.U1)):
+            zero_stmt = py.Constant(value=0.0)
+            zero_stmt.insert_before(node)
+            args = (zero_stmt.result, zero_stmt.result, node.lam, node.qarg)
+        elif isinstance(node, (uop_stmts.U2)):
+            half_pi_stmt = py.Constant(value=pi / 2)
+            half_pi_stmt.insert_before(node)
+            args = (half_pi_stmt.result, node.phi, node.lam, node.qarg)
+        else:
+            return RewriteResult()


Suggested change

if isinstance(node, (uop_stmts.RX, uop_stmts.RY, uop_stmts.RZ)):

args = (node.theta, node.qarg)

elif isinstance(node, (uop_stmts.UGate)):

args = (node.theta, node.phi, node.lam, node.qarg)

elif isinstance(node, (uop_stmts.U1)):

zero_stmt = py.Constant(value=0.0)

zero_stmt.insert_before(node)

args = (zero_stmt.result, zero_stmt.result, node.lam, node.qarg)

elif isinstance(node, (uop_stmts.U2)):

half_pi_stmt = py.Constant(value=pi / 2)

half_pi_stmt.insert_before(node)

args = (half_pi_stmt.result, node.phi, node.lam, node.qarg)

else:

return RewriteResult()

if type(node) not in PARAMETRIZED_1Q_GATES_TO_SQUIN_MAP:

return RewriteResult()

args = node.args

if isinstance(node, (uop_stmts.U1)):

zero_stmt = py.Constant(value=0.0)

zero_stmt.insert_before(node)

args = (zero_stmt.result, zero_stmt.result) + args

elif isinstance(node, (uop_stmts.U2)):

half_pi_stmt = py.Constant(value=pi / 2)

half_pi_stmt.insert_before(node)

args = (half_pi_stmt.result, ) + args

johnzl-777 added 6 commits December 2, 2025 09:02

core dialects/functionality supported with pass

2f6e8a1

parallel, global, and noise dialects now supported

90d8578

wip on converting invoke/functions

509b9cc

Merge branch 'main' into john/qasm2-to-squin

006be62

complete func conversion - don't know if it's the best way though

1fa9865

dialect handover

6552782

johnzl-777 requested review from david-pl and weinbe58 December 4, 2025 14:41

johnzl-777 linked an issue Dec 4, 2025 that may be closed by this pull request

rewrite QASM2 dialect to SQUIN #540

Open

dialect handover

d4f46bb

johnzl-777 marked this pull request as draft December 5, 2025 13:02

johnzl-777 mentioned this pull request Dec 5, 2025

QASM2-based standard library for squin #648

Open

johnzl-777 added 2 commits December 5, 2025 08:20

Merge branch 'main' into john/qasm2-to-squin

6b9e52f

use callgraph pass instead of nesting rewrite rule applications

cd53e5d

johnzl-777 marked this pull request as ready for review December 5, 2025 14:43

add missing slots arg

59dfcb0

johnzl-777 added 6 commits December 5, 2025 11:09

get rid of redundant rewrite of QASM2 const/expr to py const/expr - a…

99e66af

…lready exists

broke everything up into smaller rulesgst

045fa00

add in QASM2 adjoint to squin adjoint equivalents I missed the first …

5137de0

…round

final full test for everything

6390a23

Merge branch 'main' into john/qasm2-to-squin

0645d11

Merge branch 'main' into john/qasm2-to-squin

df35694

david-pl reviewed Dec 9, 2025

View reviewed changes

johnzl-777 added 3 commits December 9, 2025 08:44

Merge branch 'main' into john/qasm2-to-squin

3468702

get rid of unnecessary util file

5f137de

Merge branch 'main' into john/qasm2-to-squin

aea7567

weinbe58 requested changes Dec 11, 2025

View reviewed changes


		def rewrite_Statement(self, node: ir.Statement) -> RewriteResult:

		if isinstance(node, glob.UGate):

QASM2 to squin #644

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QASM2 to squin #644

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