Decompose measurement in QIR Base profile processing (microsoft#2230)

This change simplifies the decomposition of `M` and `Measure` in the
stdlib to no longer conditionally compile to different versions based on
qubit reuse capability, instead offloading that to QIR processing, which
already has similar logic.

One effect of this is simulation and circuit generation will match user
expectation and patterns in the Q# code rather than more closely showing
what occurs on hardware.

Author: swernli

compiler/qsc/src/interpret.rs

@@ -759,7 +759,6 @@ impl Interpreter {
             sim.chained.finish()
         } else {
             let mut sim = CircuitBuilder::new(CircuitConfig {
-                base_profile: self.capabilities.is_empty(),
                 max_operations: CircuitConfig::DEFAULT_MAX_OPERATIONS,
             });
 
@@ -1004,14 +1003,6 @@ fn sim_circuit_backend() -> BackendChain<SparseSim, CircuitBuilder> {
     BackendChain::new(
         SparseSim::new(),
         CircuitBuilder::new(CircuitConfig {
-            // When using in conjunction with the simulator,
-            // the circuit builder should *not* perform base profile
-            // decompositions, in order to match the simulator's behavior.
-            //
-            // Note that conditional compilation (e.g. @Config(Base) attributes)
-            // will still respect the selected profile. This also
-            // matches the behavior of the simulator.
-            base_profile: false,
             max_operations: CircuitConfig::DEFAULT_MAX_OPERATIONS,
         }),
     )

compiler/qsc/src/interpret/circuit_tests.rs

@@ -202,11 +202,10 @@ fn m_base_profile() {
         .circuit(CircuitEntryPoint::EntryPoint, false)
         .expect("circuit generation should succeed");
 
-    expect![[r"
-        q_0    ── H ──── Z ────────────────
-        q_1    ── H ──── ● ──── H ──── M ──
-                                       ╘═══
-    "]]
+    expect![[r#"
+        q_0    ── H ──── M ──
+                         ╘═══
+    "#]]
     .assert_eq(&circ.to_string());
 }
 
@@ -287,10 +286,10 @@ fn mresetz_base_profile() {
         .circuit(CircuitEntryPoint::EntryPoint, false)
         .expect("circuit generation should succeed");
 
-    expect![[r"
-        q_0    ── H ──── M ──
-                         ╘═══
-    "]]
+    expect![[r#"
+        q_0    ── H ──── M ──── |0〉 ──
+                         ╘════════════
+    "#]]
     .assert_eq(&circ.to_string());
 }
 
@@ -597,14 +596,12 @@ fn operation_with_qubits_base_profile() {
         .circuit(CircuitEntryPoint::Operation("Test.Test".into()), false)
         .expect("circuit generation should succeed");
 
-    expect![[r"
-        q_0    ── H ──── ● ──── Z ──────────────────────────────
-        q_1    ───────── X ─────┼──────────── Z ────────────────
-        q_2    ── H ─────────── ● ──── H ─────┼───── M ─────────
-                                              │      ╘══════════
-        q_3    ── H ───────────────────────── ● ──── H ──── M ──
-                                                            ╘═══
-    "]]
+    expect![[r#"
+        q_0    ── H ──── ● ──── M ──
+                         │      ╘═══
+        q_1    ───────── X ──── M ──
+                                ╘═══
+    "#]]
     .assert_eq(&circ.to_string());
 }
 
@@ -1067,33 +1064,22 @@ mod debugger_stepping {
             Profile::Base,
         );
 
-        // Surprising but expected: Reset gates would *not* normally
-        // be generated in Base Profile, but they are here, since
-        // when running in tandem with the simulator, the resulting
-        // circuit is intended to match the calls into the simulator.
-        //
-        // Note the circuit still looks different than what would be
-        // generated in Unrestricted Profile for the same code,
-        // due to conditional compilation in the standard library.
-        expect![["
+        expect![[r#"
             step:
             step:
             q_0
             step:
             q_0    ── H ──
             step:
-            q_0    ── H ──── Z ─────────────────────────
-            q_1    ── H ──── ● ──── H ──── M ──── |0〉 ──
-                                           ╘════════════
+            q_0    ── H ──── M ──
+                             ╘═══
             step:
-            q_0    ── H ──── Z ──── |0〉 ──────────────────
-            q_1    ── H ──── ● ───── H ───── M ──── |0〉 ──
-                                             ╘════════════
+            q_0    ── H ──── M ──── |0〉 ──
+                             ╘════════════
             step:
-            q_0    ── H ──── Z ──── |0〉 ──────────────────
-            q_1    ── H ──── ● ───── H ───── M ──── |0〉 ──
-                                             ╘════════════
-        "]]
+            q_0    ── H ──── M ──── |0〉 ──
+                             ╘════════════
+        "#]]
         .assert_eq(&circs);
     }
 

compiler/qsc/src/interpret/tests.rs

@@ -884,21 +884,17 @@ mod given_interpreter {
 
                 define void @ENTRYPOINT__main() #0 {
                 block_0:
-                  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 1 to %Qubit*))
-                  call void @__quantum__qis__cz__body(%Qubit* inttoptr (i64 1 to %Qubit*), %Qubit* inttoptr (i64 0 to %Qubit*))
-                  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 1 to %Qubit*))
-                  call void @__quantum__qis__m__body(%Qubit* inttoptr (i64 1 to %Qubit*), %Result* inttoptr (i64 0 to %Result*))
+                  call void @__quantum__qis__cx__body(%Qubit* inttoptr (i64 0 to %Qubit*), %Qubit* inttoptr (i64 1 to %Qubit*))
+                  call void @__quantum__qis__m__body(%Qubit* inttoptr (i64 0 to %Qubit*), %Result* inttoptr (i64 0 to %Result*))
                   call void @__quantum__rt__result_record_output(%Result* inttoptr (i64 0 to %Result*), i8* null)
                   ret void
                 }
 
-                declare void @__quantum__qis__h__body(%Qubit*)
-
-                declare void @__quantum__qis__cz__body(%Qubit*, %Qubit*)
+                declare void @__quantum__qis__m__body(%Qubit*, %Result*) #1
 
                 declare void @__quantum__rt__result_record_output(%Result*, i8*)
 
-                declare void @__quantum__qis__m__body(%Qubit*, %Result*) #1
+                declare void @__quantum__qis__cx__body(%Qubit*, %Qubit*)
 
                 attributes #0 = { "entry_point" "output_labeling_schema" "qir_profiles"="base_profile" "required_num_qubits"="2" "required_num_results"="1" }
                 attributes #1 = { "irreversible" }
@@ -1083,21 +1079,17 @@ mod given_interpreter {
 
                 define void @ENTRYPOINT__main() #0 {
                 block_0:
-                  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 1 to %Qubit*))
-                  call void @__quantum__qis__cz__body(%Qubit* inttoptr (i64 1 to %Qubit*), %Qubit* inttoptr (i64 0 to %Qubit*))
-                  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 1 to %Qubit*))
-                  call void @__quantum__qis__m__body(%Qubit* inttoptr (i64 1 to %Qubit*), %Result* inttoptr (i64 0 to %Result*))
+                  call void @__quantum__qis__cx__body(%Qubit* inttoptr (i64 0 to %Qubit*), %Qubit* inttoptr (i64 1 to %Qubit*))
+                  call void @__quantum__qis__m__body(%Qubit* inttoptr (i64 0 to %Qubit*), %Result* inttoptr (i64 0 to %Result*))
                   call void @__quantum__rt__result_record_output(%Result* inttoptr (i64 0 to %Result*), i8* null)
                   ret void
                 }
 
-                declare void @__quantum__qis__h__body(%Qubit*)
-
-                declare void @__quantum__qis__cz__body(%Qubit*, %Qubit*)
+                declare void @__quantum__qis__m__body(%Qubit*, %Result*) #1
 
                 declare void @__quantum__rt__result_record_output(%Result*, i8*)
 
-                declare void @__quantum__qis__m__body(%Qubit*, %Result*) #1
+                declare void @__quantum__qis__cx__body(%Qubit*, %Qubit*)
 
                 attributes #0 = { "entry_point" "output_labeling_schema" "qir_profiles"="base_profile" "required_num_qubits"="2" "required_num_results"="1" }
                 attributes #1 = { "irreversible" }
@@ -1131,21 +1123,17 @@ mod given_interpreter {
 
                 define void @ENTRYPOINT__main() #0 {
                 block_0:
-                  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 1 to %Qubit*))
-                  call void @__quantum__qis__cz__body(%Qubit* inttoptr (i64 1 to %Qubit*), %Qubit* inttoptr (i64 0 to %Qubit*))
-                  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 1 to %Qubit*))
-                  call void @__quantum__qis__m__body(%Qubit* inttoptr (i64 1 to %Qubit*), %Result* inttoptr (i64 0 to %Result*))
+                  call void @__quantum__qis__cx__body(%Qubit* inttoptr (i64 0 to %Qubit*), %Qubit* inttoptr (i64 1 to %Qubit*))
+                  call void @__quantum__qis__m__body(%Qubit* inttoptr (i64 0 to %Qubit*), %Result* inttoptr (i64 0 to %Result*))
                   call void @__quantum__rt__result_record_output(%Result* inttoptr (i64 0 to %Result*), i8* null)
                   ret void
                 }
 
-                declare void @__quantum__qis__h__body(%Qubit*)
-
-                declare void @__quantum__qis__cz__body(%Qubit*, %Qubit*)
+                declare void @__quantum__qis__m__body(%Qubit*, %Result*) #1
 
                 declare void @__quantum__rt__result_record_output(%Result*, i8*)
 
-                declare void @__quantum__qis__m__body(%Qubit*, %Result*) #1
+                declare void @__quantum__qis__cx__body(%Qubit*, %Qubit*)
 
                 attributes #0 = { "entry_point" "output_labeling_schema" "qir_profiles"="base_profile" "required_num_qubits"="2" "required_num_results"="1" }
                 attributes #1 = { "irreversible" }
@@ -1211,21 +1199,17 @@ mod given_interpreter {
 
                 define void @ENTRYPOINT__main() #0 {
                 block_0:
-                  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 1 to %Qubit*))
-                  call void @__quantum__qis__cz__body(%Qubit* inttoptr (i64 1 to %Qubit*), %Qubit* inttoptr (i64 0 to %Qubit*))
-                  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 1 to %Qubit*))
-                  call void @__quantum__qis__m__body(%Qubit* inttoptr (i64 1 to %Qubit*), %Result* inttoptr (i64 0 to %Result*))
+                  call void @__quantum__qis__cx__body(%Qubit* inttoptr (i64 0 to %Qubit*), %Qubit* inttoptr (i64 1 to %Qubit*))
+                  call void @__quantum__qis__m__body(%Qubit* inttoptr (i64 0 to %Qubit*), %Result* inttoptr (i64 0 to %Result*))
                   call void @__quantum__rt__result_record_output(%Result* inttoptr (i64 0 to %Result*), i8* null)
                   ret void
                 }
 
-                declare void @__quantum__qis__h__body(%Qubit*)
-
-                declare void @__quantum__qis__cz__body(%Qubit*, %Qubit*)
+                declare void @__quantum__qis__m__body(%Qubit*, %Result*) #1
 
                 declare void @__quantum__rt__result_record_output(%Result*, i8*)
 
-                declare void @__quantum__qis__m__body(%Qubit*, %Result*) #1
+                declare void @__quantum__qis__cx__body(%Qubit*, %Qubit*)
 
                 attributes #0 = { "entry_point" "output_labeling_schema" "qir_profiles"="base_profile" "required_num_qubits"="2" "required_num_results"="1" }
                 attributes #1 = { "irreversible" }
@@ -1271,21 +1255,17 @@ mod given_interpreter {
 
                 define void @ENTRYPOINT__main() #0 {
                 block_0:
-                  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 1 to %Qubit*))
-                  call void @__quantum__qis__cz__body(%Qubit* inttoptr (i64 1 to %Qubit*), %Qubit* inttoptr (i64 0 to %Qubit*))
-                  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 1 to %Qubit*))
-                  call void @__quantum__qis__m__body(%Qubit* inttoptr (i64 1 to %Qubit*), %Result* inttoptr (i64 0 to %Result*))
+                  call void @__quantum__qis__cx__body(%Qubit* inttoptr (i64 0 to %Qubit*), %Qubit* inttoptr (i64 1 to %Qubit*))
+                  call void @__quantum__qis__m__body(%Qubit* inttoptr (i64 0 to %Qubit*), %Result* inttoptr (i64 0 to %Result*))
                   call void @__quantum__rt__result_record_output(%Result* inttoptr (i64 0 to %Result*), i8* null)
                   ret void
                 }
 
-                declare void @__quantum__qis__h__body(%Qubit*)
-
-                declare void @__quantum__qis__cz__body(%Qubit*, %Qubit*)
+                declare void @__quantum__qis__m__body(%Qubit*, %Result*) #1
 
                 declare void @__quantum__rt__result_record_output(%Result*, i8*)
 
-                declare void @__quantum__qis__m__body(%Qubit*, %Result*) #1
+                declare void @__quantum__qis__cx__body(%Qubit*, %Qubit*)
 
                 attributes #0 = { "entry_point" "output_labeling_schema" "qir_profiles"="base_profile" "required_num_qubits"="2" "required_num_results"="1" }
                 attributes #1 = { "irreversible" }

compiler/qsc_circuit/src/builder.rs

@@ -56,48 +56,34 @@ impl Backend for Builder {
     }
 
     fn m(&mut self, q: usize) -> Self::ResultType {
-        if self.config.base_profile {
-            // defer the measurement and reset the qubit
-            self.remapper.mreset(q)
-        } else {
-            let mapped_q = self.map(q);
-            // In the Circuit schema, result id is per-qubit
-            let res_id = self.num_measurements_for_qubit(mapped_q);
-            let id = self.remapper.m(q);
+        let mapped_q = self.map(q);
+        // In the Circuit schema, result id is per-qubit
+        let res_id = self.num_measurements_for_qubit(mapped_q);
+        let id = self.remapper.m(q);
 
-            self.push_gate(measurement_gate(mapped_q.0, res_id));
-            id
-        }
+        self.push_gate(measurement_gate(mapped_q.0, res_id));
+        id
     }
 
     fn mresetz(&mut self, q: usize) -> Self::ResultType {
-        if self.config.base_profile {
-            // defer the measurement
-            self.remapper.mreset(q)
-        } else {
-            let mapped_q = self.map(q);
-            // In the Circuit schema, result id is per-qubit
-            let res_id = self.num_measurements_for_qubit(mapped_q);
-            // We don't actually need the Remapper since we're not
-            // remapping any qubits, but it's handy for keeping track of measurements
-            let id = self.remapper.m(q);
-
-            // Ideally MResetZ would be atomic but we don't currently have
-            // a way to visually represent that. So decompose it into
-            // a measurement and a reset gate.
-            self.push_gate(measurement_gate(mapped_q.0, res_id));
-            self.push_gate(gate(KET_ZERO, [mapped_q]));
-            id
-        }
+        let mapped_q = self.map(q);
+        // In the Circuit schema, result id is per-qubit
+        let res_id = self.num_measurements_for_qubit(mapped_q);
+        // We don't actually need the Remapper since we're not
+        // remapping any qubits, but it's handy for keeping track of measurements
+        let id = self.remapper.m(q);
+
+        // Ideally MResetZ would be atomic but we don't currently have
+        // a way to visually represent that. So decompose it into
+        // a measurement and a reset gate.
+        self.push_gate(measurement_gate(mapped_q.0, res_id));
+        self.push_gate(gate(KET_ZERO, [mapped_q]));
+        id
     }
 
     fn reset(&mut self, q: usize) {
-        if self.config.base_profile {
-            self.remapper.reset(q);
-        } else {
-            let mapped_q = self.map(q);
-            self.push_gate(gate(KET_ZERO, [mapped_q]));
-        }
+        let mapped_q = self.map(q);
+        self.push_gate(gate(KET_ZERO, [mapped_q]));
     }
 
     fn rx(&mut self, theta: f64, q: usize) {
@@ -267,18 +253,6 @@ impl Builder {
     }
 
     fn finish_circuit(&self, mut circuit: Circuit) -> Circuit {
-        // add deferred measurements
-        if self.config.base_profile {
-            for (qubit, _) in &self.remapper.qubit_measurement_counts {
-                if self.max_ops_exceeded || circuit.operations.len() >= self.config.max_operations {
-                    break;
-                }
-
-                // guaranteed one measurement per qubit, so result is always 0
-                circuit.operations.push(measurement_gate(qubit.0, 0));
-            }
-        }
-
         // add qubit declarations
         for i in 0..self.remapper.num_qubits() {
             let num_measurements = self.num_measurements_for_qubit(WireId(i));
@@ -408,16 +382,6 @@ impl Remapper {
         id
     }
 
-    fn mreset(&mut self, q: usize) -> usize {
-        let id = self.m(q);
-        self.reset(q);
-        id
-    }
-
-    fn reset(&mut self, q: usize) {
-        self.qubit_map.remove(q);
-    }
-
     fn qubit_allocate(&mut self) -> usize {
         let id = self.next_qubit_id;
         self.next_qubit_id += 1;

compiler/qsc_circuit/src/builder/tests.rs

@@ -6,10 +6,7 @@ use expect_test::expect;
 
 #[test]
 fn exceed_max_operations() {
-    let mut builder = Builder::new(Config {
-        base_profile: false,
-        max_operations: 2,
-    });
+    let mut builder = Builder::new(Config { max_operations: 2 });
 
     let q = builder.qubit_allocate();
 
@@ -31,10 +28,7 @@ fn exceed_max_operations() {
 
 #[test]
 fn exceed_max_operations_deferred_measurements() {
-    let mut builder = Builder::new(Config {
-        base_profile: true, // deferred measurements
-        max_operations: 2,
-    });
+    let mut builder = Builder::new(Config { max_operations: 2 });
 
     let q = builder.qubit_allocate();
 
@@ -48,11 +42,10 @@ fn exceed_max_operations_deferred_measurements() {
 
     // The current behavior is to silently truncate the circuit
     // if it exceeds the maximum allowed number of operations.
-    // The measurement will be dropped.
+    // The second X will be dropped.
     expect![[r#"
-        q_0    ── X ──
-
-        q_1    ── X ──
+        q_0    ── X ──── M ──
+                         ╘═══
     "#]]
     .assert_eq(&circuit.to_string());
 }