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Remove implicit modifier handling during OpenQASM lowering #2529

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Jun 16, 2025
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Remove implicit modifier handling during OpenQASM lowering #2529

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b355817
Remove implicit modifier handling during OpenQASM lowering
idavis Jun 13, 2025
5f446c3
Update docs and use matching gates
idavis Jun 16, 2025
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97 changes: 20 additions & 77 deletions compiler/qsc_qasm/src/semantic/lowerer.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,6 @@ use crate::convert::safe_i64_to_f64;
use crate::parser::ast::list_from_iter;
use crate::parser::ast::List;
use crate::parser::QasmSource;
use crate::semantic::ast::Expr;
use crate::semantic::types::base_types_equal;
use crate::semantic::types::can_cast_literal;
use crate::semantic::types::can_cast_literal_with_value_knowledge;
Expand Down Expand Up @@ -278,10 +277,7 @@ impl Lowerer {
}]
}

/// Define the standard gates in the symbol table.
/// The sdg, tdg, crx, cry, crz, and ch are defined
/// as their bare gates, and modifiers are applied
/// when calling them.
/// Define the `OpenQASM` 3.0 standard gates in the symbol table.
fn define_stdgates(&mut self, span: Span) {
fn gate_symbol(name: &str, cargs: u32, qargs: u32) -> Symbol {
Symbol::new(
Expand All @@ -298,21 +294,29 @@ impl Lowerer {
gate_symbol("y", 0, 1),
gate_symbol("z", 0, 1),
gate_symbol("h", 0, 1),
gate_symbol("ch", 0, 2),
gate_symbol("s", 0, 1),
gate_symbol("sdg", 0, 1),
gate_symbol("t", 0, 1),
gate_symbol("tdg", 0, 1),
gate_symbol("sx", 0, 1),
gate_symbol("rx", 1, 1),
gate_symbol("ry", 1, 1),
gate_symbol("rz", 1, 1),
gate_symbol("crx", 1, 2),
gate_symbol("cry", 1, 2),
gate_symbol("crz", 1, 2),
gate_symbol("cx", 0, 2),
gate_symbol("cy", 0, 2),
gate_symbol("cz", 0, 2),
gate_symbol("cp", 1, 2),
gate_symbol("swap", 0, 2),
gate_symbol("cswap", 0, 3),
gate_symbol("ccx", 0, 3),
gate_symbol("cu", 4, 2),
gate_symbol("CX", 0, 2),
gate_symbol("phase", 1, 1),
gate_symbol("cphase", 1, 2),
gate_symbol("id", 0, 1),
gate_symbol("u1", 1, 1),
gate_symbol("u2", 2, 1),
Expand All @@ -326,10 +330,7 @@ impl Lowerer {
}
}

/// Define the standard gates in the symbol table.
/// The sdg, tdg, crx, cry, crz, and ch are defined
/// as their bare gates, and modifiers are applied
/// when calling them.
/// Define the `OpenQASM` 2.0 standard gates in the symbol table.
fn define_qelib1_gates(&mut self, span: Span) {
fn gate_symbol(name: &str, cargs: u32, qargs: u32) -> Symbol {
Symbol::new(
Expand All @@ -346,30 +347,29 @@ impl Lowerer {
gate_symbol("u3", 3, 1),
gate_symbol("u2", 2, 1),
gate_symbol("u1", 1, 1),
//gate_symbol("cx", 0, 2), // handled as a modified x
gate_symbol("cx", 0, 2),
gate_symbol("id", 0, 1),
// --- QE Standard Gates ---
gate_symbol("x", 0, 1),
gate_symbol("y", 0, 1),
gate_symbol("z", 0, 1),
gate_symbol("h", 0, 1),
gate_symbol("s", 0, 1),
// sdg handled as a modified s
gate_symbol("sdg", 0, 1),
gate_symbol("t", 0, 1),
// tdg handled as a modified t

gate_symbol("tdg", 0, 1),
// --- Standard rotations ---
gate_symbol("rx", 1, 1),
gate_symbol("ry", 1, 1),
gate_symbol("rz", 1, 1),
// --- QE Standard User-Defined Gates ---
//gate_symbol("cz", 0, 2), // handled as a modified z
//gate_symbol("cy", 0, 2), // handled as a modified y
// ch handled as a modified h
gate_symbol("cz", 0, 2),
gate_symbol("cy", 0, 2),
gate_symbol("ch", 0, 2),
gate_symbol("ccx", 0, 3),
// crz handled as a modified rz
// cu1 handled as a modified u1
// cu3 handled as a modified u3
gate_symbol("crz", 1, 2),
gate_symbol("cu1", 1, 2),
gate_symbol("cu3", 3, 2),
];
for gate in gates {
let name = gate.name.clone();
Expand Down Expand Up @@ -1892,18 +1892,7 @@ impl Lowerer {
self.push_unsupported_error_message("gate call duration", duration.span);
}

let mut name = stmt.name.name.to_string();
if let Some((gate_name, implicit_modifier)) =
self.try_get_qsharp_name_and_implicit_modifiers(&name, stmt.name.span)
{
// Override the gate name if we mapped with modifiers.
name = gate_name;

// 2. Get implicit modifiers and make them explicit.
// Q: Do we need this during lowering?
// A: Yes, we need it to check the gate_call arity.
modifiers.push(implicit_modifier);
}
let name = stmt.name.name.to_string();

// need a workaround for qiskit generating gate calls without having declared the gate
self.define_qiskit_standard_gate_if_needed(&name, stmt.name.span);
Expand Down Expand Up @@ -4129,52 +4118,6 @@ impl Lowerer {
let error = crate::Error(kind);
WithSource::from_map(&self.source_map, error)
}

fn try_get_qsharp_name_and_implicit_modifiers<S: AsRef<str>>(
&self,
gate_name: S,
name_span: Span,
) -> Option<(String, semantic::QuantumGateModifier)> {
use semantic::GateModifierKind::*;

let make_modifier = |kind| semantic::QuantumGateModifier {
span: name_span,
modifier_keyword_span: name_span,
kind,
};
let ctrl_expr = Expr::uint(1, Span::default());

if self.version == Some(QASM2_VERSION) {
match gate_name.as_ref() {
"cx" => Some(("x".to_string(), make_modifier(Ctrl(ctrl_expr)))),
"sdg" => Some(("s".to_string(), make_modifier(Inv))),
"tdg" => Some(("t".to_string(), make_modifier(Inv))),
"cz" => Some(("z".to_string(), make_modifier(Ctrl(ctrl_expr)))),
"cy" => Some(("y".to_string(), make_modifier(Ctrl(ctrl_expr)))),
"ch" => Some(("h".to_string(), make_modifier(Ctrl(ctrl_expr)))),
"crz" => Some(("rz".to_string(), make_modifier(Ctrl(ctrl_expr)))),
"cu1" => Some(("u1".to_string(), make_modifier(Ctrl(ctrl_expr)))),
"cu3" => Some(("u3".to_string(), make_modifier(Ctrl(ctrl_expr)))),
_ => None,
}
} else {
match gate_name.as_ref() {
"cy" => Some(("y".to_string(), make_modifier(Ctrl(ctrl_expr)))),
"cz" => Some(("z".to_string(), make_modifier(Ctrl(ctrl_expr)))),
"ch" => Some(("h".to_string(), make_modifier(Ctrl(ctrl_expr)))),
"crx" => Some(("rx".to_string(), make_modifier(Ctrl(ctrl_expr)))),
"cry" => Some(("ry".to_string(), make_modifier(Ctrl(ctrl_expr)))),
"crz" => Some(("rz".to_string(), make_modifier(Ctrl(ctrl_expr)))),
"cswap" => Some(("swap".to_string(), make_modifier(Ctrl(ctrl_expr)))),
"sdg" => Some(("s".to_string(), make_modifier(Inv))),
"tdg" => Some(("t".to_string(), make_modifier(Inv))),
// Gates for OpenQASM 2 backwards compatibility
"CX" => Some(("x".to_string(), make_modifier(Ctrl(ctrl_expr)))),
"cphase" => Some(("phase".to_string(), make_modifier(Ctrl(ctrl_expr)))),
_ => None,
}
}
}
}

fn wrap_expr_in_cast_expr(ty: Type, rhs: semantic::Expr) -> semantic::Expr {
Expand Down
18 changes: 9 additions & 9 deletions compiler/qsc_qasm/src/semantic/tests.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -191,50 +191,50 @@ fn semantic_errors_map_to_their_corresponding_file_specific_spans() {
Stmt [196-206]:
annotations: <empty>
kind: ClassicalDeclarationStmt [196-206]:
symbol_id: 32
symbol_id: 40
ty_span: [196-199]
init_expr: Expr [204-205]:
ty: const bit
kind: Lit: Bit(1)
Stmt [211-227]:
annotations: <empty>
kind: ClassicalDeclarationStmt [211-227]:
symbol_id: 32
symbol_id: 40
ty_span: [211-215]
init_expr: Expr [220-226]:
ty: bool
kind: BinaryOpExpr:
op: AndL
lhs: Expr [220-221]:
ty: unknown
kind: SymbolId(33)
kind: SymbolId(41)
rhs: Expr [225-226]:
ty: bool
kind: Cast [0-0]:
ty: bool
expr: Expr [225-226]:
ty: bit
kind: SymbolId(32)
kind: SymbolId(40)
Stmt [140-154]:
annotations: <empty>
kind: ClassicalDeclarationStmt [140-154]:
symbol_id: 34
symbol_id: 42
ty_span: [140-145]
init_expr: Expr [150-153]:
ty: const angle
kind: Lit: Angle(0.7168146928204138)
Stmt [159-179]:
annotations: <empty>
kind: ClassicalDeclarationStmt [159-179]:
symbol_id: 35
symbol_id: 43
ty_span: [159-164]
init_expr: Expr [169-178]:
ty: float
kind: BinaryOpExpr:
op: Add
lhs: Expr [169-170]:
ty: angle
kind: SymbolId(34)
kind: SymbolId(42)
rhs: Expr [173-178]:
ty: float
kind: Cast [0-0]:
Expand All @@ -245,11 +245,11 @@ fn semantic_errors_map_to_their_corresponding_file_specific_spans() {
Stmt [74-84]:
annotations: <empty>
kind: ClassicalDeclarationStmt [74-84]:
symbol_id: 37
symbol_id: 45
ty_span: [74-77]
init_expr: Expr [82-83]:
ty: unknown
kind: SymbolId(36)
kind: SymbolId(44)

[Qasm.Lowerer.UndefinedSymbol

Expand Down
4 changes: 2 additions & 2 deletions compiler/qsc_qasm/src/semantic/tests/lowerer_errors.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -84,9 +84,9 @@ fn check_lowerer_error_spans_are_correct() {

x inconsistent types in alias expression: Expr [842-859]:
| ty: array[int, 2]
| kind: SymbolId(37), Expr [863-880]:
| kind: SymbolId(45), Expr [863-880]:
| ty: array[angle, 2]
| kind: SymbolId(38)
| kind: SymbolId(46)
,-[Test.qasm:37:1]
36 | array[angle, 2] alias_component_2 = {1.0, 2.0};
37 | let alias = alias_component_1 ++ alias_component_2;
Expand Down
10 changes: 5 additions & 5 deletions compiler/qsc_qasm/src/tests/statement/gate_call.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1493,8 +1493,8 @@ fn qasm2_all_qiskit_stdgates_can_be_called_included() -> miette::Result<(), Vec<
csdg(q[0], q[1]);
sxdg(q[0]);
csx(q[0], q[1]);
Controlled u1([q[1]], (Std.OpenQASM.Angle.DoubleAsAngle(Std.Math.PI() / 2., 53), q[0]));
Controlled u3([q[1]], (Std.OpenQASM.Angle.DoubleAsAngle(Std.Math.PI() / 2., 53), Std.OpenQASM.Angle.DoubleAsAngle(Std.Math.PI() / 4., 53), Std.OpenQASM.Angle.DoubleAsAngle(Std.Math.PI() / 8., 53), q[0]));
cu1(Std.OpenQASM.Angle.DoubleAsAngle(Std.Math.PI() / 2., 53), q[1], q[0]);
cu3(Std.OpenQASM.Angle.DoubleAsAngle(Std.Math.PI() / 2., 53), Std.OpenQASM.Angle.DoubleAsAngle(Std.Math.PI() / 4., 53), Std.OpenQASM.Angle.DoubleAsAngle(Std.Math.PI() / 8., 53), q[1], q[0]);
rccx(q[0], q[1], q[2]);
c3sqrtx(q[0], q[1], q[2], q[3]);
c3x(q[0], q[1], q[2], q[3]);
Expand Down Expand Up @@ -1542,9 +1542,9 @@ fn qasm2_broadcast_two_qubit_gate() -> miette::Result<(), Vec<Report>> {
import Std.OpenQASM.Intrinsic.*;
let ctrls = QIR.Runtime.AllocateQubitArray(3);
let targets = QIR.Runtime.AllocateQubitArray(3);
Controlled x([ctrls[0]], targets[0]);
Controlled x([ctrls[1]], targets[1]);
Controlled x([ctrls[2]], targets[2]);
cx(ctrls[0], targets[0]);
cx(ctrls[1], targets[1]);
cx(ctrls[2], targets[2]);
"#]]
.assert_eq(&qsharp);
Ok(())
Expand Down
30 changes: 15 additions & 15 deletions compiler/qsc_qasm/src/tests/statement/implicit_modified_gate_call.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,7 @@ fn cy_gate_can_be_called() -> miette::Result<(), Vec<Report>> {
import Std.OpenQASM.Intrinsic.*;
let ctl = QIR.Runtime.__quantum__rt__qubit_allocate();
let target = QIR.Runtime.__quantum__rt__qubit_allocate();
Controlled y([ctl], target);
cy(ctl, target);
"#]]
.assert_eq(&qsharp);
Ok(())
Expand All @@ -39,7 +39,7 @@ fn cz_gate_can_be_called() -> miette::Result<(), Vec<Report>> {
import Std.OpenQASM.Intrinsic.*;
let ctl = QIR.Runtime.__quantum__rt__qubit_allocate();
let target = QIR.Runtime.__quantum__rt__qubit_allocate();
Controlled z([ctl], target);
cz(ctl, target);
"#]]
.assert_eq(&qsharp);
Ok(())
Expand All @@ -59,7 +59,7 @@ fn ch_gate_can_be_called() -> miette::Result<(), Vec<Report>> {
import Std.OpenQASM.Intrinsic.*;
let ctl = QIR.Runtime.__quantum__rt__qubit_allocate();
let target = QIR.Runtime.__quantum__rt__qubit_allocate();
Controlled h([ctl], target);
ch(ctl, target);
"#]]
.assert_eq(&qsharp);
Ok(())
Expand All @@ -77,7 +77,7 @@ fn sdg_gate_can_be_called() -> miette::Result<(), Vec<Report>> {
expect![[r#"
import Std.OpenQASM.Intrinsic.*;
let q = QIR.Runtime.__quantum__rt__qubit_allocate();
Adjoint s(q);
sdg(q);
"#]]
.assert_eq(&qsharp);
Ok(())
Expand All @@ -95,7 +95,7 @@ fn tdg_gate_can_be_called() -> miette::Result<(), Vec<Report>> {
expect![[r#"
import Std.OpenQASM.Intrinsic.*;
let q = QIR.Runtime.__quantum__rt__qubit_allocate();
Adjoint t(q);
tdg(q);
"#]]
.assert_eq(&qsharp);
Ok(())
Expand All @@ -115,10 +115,10 @@ fn crx_gate_can_be_called() -> miette::Result<(), Vec<Report>> {
import Std.OpenQASM.Intrinsic.*;
let ctl = QIR.Runtime.__quantum__rt__qubit_allocate();
let target = QIR.Runtime.__quantum__rt__qubit_allocate();
Controlled rx([ctl], (new Std.OpenQASM.Angle.Angle {
crx(new Std.OpenQASM.Angle.Angle {
Value = 716770142402832,
Size = 53
}, target));
}, ctl, target);
"#]]
.assert_eq(&qsharp);
Ok(())
Expand All @@ -138,10 +138,10 @@ fn cry_gate_can_be_called() -> miette::Result<(), Vec<Report>> {
import Std.OpenQASM.Intrinsic.*;
let ctl = QIR.Runtime.__quantum__rt__qubit_allocate();
let target = QIR.Runtime.__quantum__rt__qubit_allocate();
Controlled ry([ctl], (new Std.OpenQASM.Angle.Angle {
cry(new Std.OpenQASM.Angle.Angle {
Value = 716770142402832,
Size = 53
}, target));
}, ctl, target);
"#]]
.assert_eq(&qsharp);
Ok(())
Expand All @@ -161,10 +161,10 @@ fn crz_gate_can_be_called() -> miette::Result<(), Vec<Report>> {
import Std.OpenQASM.Intrinsic.*;
let ctl = QIR.Runtime.__quantum__rt__qubit_allocate();
let target = QIR.Runtime.__quantum__rt__qubit_allocate();
Controlled rz([ctl], (new Std.OpenQASM.Angle.Angle {
crz(new Std.OpenQASM.Angle.Angle {
Value = 716770142402832,
Size = 53
}, target));
}, ctl, target);
"#]]
.assert_eq(&qsharp);
Ok(())
Expand All @@ -184,7 +184,7 @@ fn cswap_gate_can_be_called() -> miette::Result<(), Vec<Report>> {
import Std.OpenQASM.Intrinsic.*;
let ctl = QIR.Runtime.__quantum__rt__qubit_allocate();
let q = QIR.Runtime.AllocateQubitArray(2);
Controlled swap([ctl], (q[0], q[1]));
cswap(ctl, q[0], q[1]);
"#]]
.assert_eq(&qsharp);
Ok(())
Expand All @@ -204,7 +204,7 @@ fn legacy_cx_gate_can_be_called() -> miette::Result<(), Vec<Report>> {
import Std.OpenQASM.Intrinsic.*;
let ctl = QIR.Runtime.__quantum__rt__qubit_allocate();
let target = QIR.Runtime.__quantum__rt__qubit_allocate();
Controlled x([ctl], target);
CX(ctl, target);
"#]]
.assert_eq(&qsharp);
Ok(())
Expand All @@ -224,10 +224,10 @@ fn legacy_cphase_gate_can_be_called() -> miette::Result<(), Vec<Report>> {
import Std.OpenQASM.Intrinsic.*;
let ctl = QIR.Runtime.__quantum__rt__qubit_allocate();
let target = QIR.Runtime.__quantum__rt__qubit_allocate();
Controlled phase([ctl], (new Std.OpenQASM.Angle.Angle {
cphase(new Std.OpenQASM.Angle.Angle {
Value = 1433540284805665,
Size = 53
}, target));
}, ctl, target);
"#]]
.assert_eq(&qsharp);
Ok(())
Expand Down
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