Adjoint canonicalization

mlir/include/Quantum/IR/QuantumOps.td

@@ -384,6 +384,7 @@ def CustomOp : UnitaryGate_Op<"custom", [DifferentiableGate, NoMemoryEffect,
             return getParams();
         }
     }];
+    let hasCanonicalizeMethod = 1;
 }
 
 def GlobalPhaseOp : UnitaryGate_Op<"gphase", [DifferentiableGate, AttrSizedOperandSegments]> {

mlir/lib/Quantum/IR/QuantumOps.cpp

@@ -12,8 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#include "mlir/Dialect/Arith/IR/Arith.h"
 #include "mlir/IR/Builders.h"
 #include "mlir/IR/OpImplementation.h"
+#include "llvm/ADT/StringSet.h"
 #include "llvm/ADT/TypeSwitch.h"
 #include <optional>
 
@@ -34,6 +36,34 @@ using namespace catalyst::quantum;
 //===----------------------------------------------------------------------===//
 // Quantum op canonicalizers.
 //===----------------------------------------------------------------------===//
+static const mlir::StringSet<> hermitianOps = {"Hadamard", "PauliX", "PauliY", "PauliZ", "CNOT",
+                                               "CY",       "CZ",     "SWAP",   "Toffoli"};
+static const mlir::StringSet<> rotationsOps = {"RX",  "RY",  "RZ",  "PhaseShift",           "Rot",
+                                               "CRX", "CRY", "CRZ", "ControlledPhaseShift", "CRot"};
+LogicalResult CustomOp::canonicalize(CustomOp op, mlir::PatternRewriter &rewriter)
+{
+    if (op.getAdjoint()) {
+        auto name = op.getGateName();
+        if (hermitianOps.contains(name)) {
+            op.setAdjoint(false);
+            return success();
+        }
+        else if (rotationsOps.contains(name)) {
+            auto params = op.getParams();
+            SmallVector<Value> paramsMinus;
+            for (auto param : params) {
+                rewriter.create<mlir::arith::NegFOp>(op.getLoc(), param);
+            }
+            auto adjointOp = rewriter.create<CustomOp>(op.getLoc(), op.getOutQubits().getTypes(), op.getOutCtrlQubits().getTypes(),
+                                                     paramsMinus, op.getInQubits(), name, nullptr,
+                                                     op.getInCtrlQubits(), op.getInCtrlValues());
+            rewriter.replaceOp(op, adjointOp.getResults());
+            return success();
+        }
+        return failure();
+    };
+    return failure();
+}
 
 LogicalResult DeallocOp::canonicalize(DeallocOp dealloc, mlir::PatternRewriter &rewriter)
 {

mlir/lib/Quantum/Transforms/merge_rotation.cpp

@@ -62,6 +62,7 @@ struct MergeRotationsPass : impl::MergeRotationsPassBase<MergeRotationsPass> {
         }
 
         RewritePatternSet patterns(&getContext());
+        catalyst::quantum::CustomOp::getCanonicalizationPatterns(patterns, &getContext());
         populateMergeRotationsPatterns(patterns);
 
         if (failed(applyPatternsAndFoldGreedily(targetfunc, std::move(patterns)))) {