Fixes for simulator qubit management (#303)

This change includes two bugfixes: - Evaluator now checks for qubit argument uniques on intrinsic gate invocation to avoid triggering a panic in the simulator (treated instead as a runtime error). - Updates to a simulator package with the bug fix for dumping state after a swap of two qubits where one has been released (see qir-alliance/qir-runner#67)
microsoft · May 12, 2023 · c8afd68 · c8afd68
1 parent d069216
commit c8afd68
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Showing 5 changed files with 111 additions and 4 deletions.
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/compiler/qsc_eval/Cargo.toml b/compiler/qsc_eval/Cargo.toml
@@ -12,8 +12,8 @@ license.workspace = true
 miette = { workspace = true }
 num-bigint = { workspace = true }
 num-complex = { workspace = true }
-qir-backend = { git = "https://github.com/qir-alliance/qir-runner", rev = "617fa33e0966579c3ef5cf55ce20c7d2d76c09a7" }
-qir-stdlib = { git = "https://github.com/qir-alliance/qir-runner", rev = "617fa33e0966579c3ef5cf55ce20c7d2d76c09a7" }
+qir-backend = { git = "https://github.com/qir-alliance/qir-runner", rev = "7141d6ebc0a573dfe2871a362b46d98dfe6f751c" }
+qir-stdlib = { git = "https://github.com/qir-alliance/qir-runner", rev = "7141d6ebc0a573dfe2871a362b46d98dfe6f751c" }
 qsc_data_structures = { path = "../qsc_data_structures" }
 qsc_hir = { path = "../qsc_hir" }
 rand =  { workspace = true }

diff --git a/compiler/qsc_eval/src/intrinsic.rs b/compiler/qsc_eval/src/intrinsic.rs
@@ -166,6 +166,9 @@ fn invoke_quantum_intrinsic(
                 $(stringify!($op2) => {
                     match args.try_into_tuple().with_span(args_span)?.as_ref() {
                         [x, y] =>  {
+                            if x == y {
+                                return Break(Reason::Error(Error::QubitUniqueness(args_span)));
+                            }
                             $op2(
                                 x.clone().try_into().with_span(args_span)?,
                                 y.clone().try_into().with_span(args_span)?,
@@ -178,6 +181,9 @@ fn invoke_quantum_intrinsic(
                 $(stringify!($op3) => {
                     match args.try_into_tuple().with_span(args_span)?.as_ref() {
                         [x, y, z] => {
+                            if x == y || y == z || x == z {
+                                return Break(Reason::Error(Error::QubitUniqueness(args_span)));
+                            }
                             $op3(
                                 x.clone().try_into().with_span(args_span)?,
                                 y.clone().try_into().with_span(args_span)?,

diff --git a/compiler/qsc_eval/src/intrinsic/tests.rs b/compiler/qsc_eval/src/intrinsic/tests.rs
@@ -882,3 +882,101 @@ fn qubit_release_non_zero_failure() {
         "#]],
     );
 }
+
+#[test]
+fn qubit_not_unique_two_qubit_error() {
+    check_intrinsic_output(
+        "",
+        indoc! {"{
+            use q = Qubit();
+            CNOT(q , q);
+        }"},
+        &expect![[r#"
+            QubitUniqueness(
+                Span {
+                    lo: 32166,
+                    hi: 32183,
+                },
+            )
+        "#]],
+    );
+}
+
+#[test]
+fn qubit_not_unique_two_qubit_rotation_error() {
+    check_intrinsic_output(
+        "",
+        indoc! {"{
+            use q = Qubit();
+            Rxx(0.1, q, q);
+        }"},
+        &expect![[r#"
+            QubitUniqueness(
+                Span {
+                    lo: 45069,
+                    hi: 45092,
+                },
+            )
+        "#]],
+    );
+}
+
+#[test]
+fn qubit_not_unique_three_qubit_error_first_second() {
+    check_intrinsic_output(
+        "",
+        indoc! {"{
+            use q = Qubit();
+            use a = Qubit();
+            CCNOT(q , q, a);
+        }"},
+        &expect![[r#"
+            QubitUniqueness(
+                Span {
+                    lo: 31122,
+                    hi: 31150,
+                },
+            )
+        "#]],
+    );
+}
+
+#[test]
+fn qubit_not_unique_three_qubit_error_first_third() {
+    check_intrinsic_output(
+        "",
+        indoc! {"{
+            use q = Qubit();
+            use a = Qubit();
+            CCNOT(q , a, q);
+        }"},
+        &expect![[r#"
+            QubitUniqueness(
+                Span {
+                    lo: 31122,
+                    hi: 31150,
+                },
+            )
+        "#]],
+    );
+}
+
+#[test]
+fn qubit_not_unique_three_qubit_error_second_third() {
+    check_intrinsic_output(
+        "",
+        indoc! {"{
+            use q = Qubit();
+            use a = Qubit();
+            CCNOT(a , q, q);
+        }"},
+        &expect![[r#"
+            QubitUniqueness(
+                Span {
+                    lo: 31122,
+                    hi: 31150,
+                },
+            )
+        "#]],
+    );
+}
diff --git a/compiler/qsc_eval/src/lib.rs b/compiler/qsc_eval/src/lib.rs
@@ -85,6 +85,9 @@ pub enum Error {
     #[error("output failure")]
     Output(#[label("failed to generate output")] Span),
 
+    #[error("qubits in gate invocation are not unique")]
+    QubitUniqueness(#[label] Span),
+
     #[error("range with step size of zero")]
     RangeStepZero(#[label("invalid range")] Span),