🔥 Remove ToffoliTable from DD Package (#380)

## Description

Fixes #339 

## Checklist:

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- [x] The pull request only contains commits that are related to it.
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Signed-off-by: Lukas Burgholzer <lukas.burgholzer@jku.at>

include/dd/Operations.hpp

@@ -31,15 +31,6 @@ qc::MatrixDD getStandardOperationDD(const qc::StandardOperation* op,
     gm = dd::Hmat;
     break;
   case qc::X: {
-    qc::MatrixDD e{};
-    if (controls.size() > 1U) { // Toffoli
-      e = dd->toffoliTable.lookup(nqubits, controls, target);
-      if (e.p == nullptr) {
-        e = dd->makeGateDD(dd::Xmat, nqubits, controls, target, startQubit);
-        dd->toffoliTable.insert(nqubits, controls, target, e);
-      }
-      return e;
-    }
     gm = dd::Xmat;
     break;
   }

include/dd/Package.hpp

@@ -10,7 +10,6 @@
 #include "dd/GateMatrixDefinitions.hpp"
 #include "dd/Package_fwd.hpp"
 #include "dd/StochasticNoiseOperationTable.hpp"
-#include "dd/ToffoliTable.hpp"
 #include "dd/UnaryComputeTable.hpp"
 #include "dd/UniqueTable.hpp"
 #include "operations/Control.hpp"
@@ -270,7 +269,6 @@ template <class Config> class Package {
       matrixKronecker.clear();
       matrixVectorMultiplication.clear();
       matrixMatrixMultiplication.clear();
-      toffoliTable.clear();
       clearIdentityTable();
       stochasticNoiseOperationCache.clear();
       densityAdd.clear();
@@ -1293,8 +1291,6 @@ template <class Config> class Package {
     vectorKronecker.clear();
     matrixKronecker.clear();
 
-    toffoliTable.clear();
-
     clearIdentityTable();
 
     stochasticNoiseOperationCache.clear();
@@ -2445,12 +2441,7 @@ template <class Config> class Package {
     return ident3;
   }
 
-  ///
-  /// Toffoli gates
-  ///
 public:
-  ToffoliTable<mEdge> toffoliTable{};
-
   ///
   /// Identity matrices
   ///
@@ -3691,9 +3682,6 @@ template <class Config> class Package {
               << sizeof(typename decltype(matrixKronecker)::Entry)
               << " bytes (aligned "
               << alignof(typename decltype(matrixKronecker)::Entry) << " bytes)"
-              << "\n  ToffoliTable::Entry size: "
-              << sizeof(ToffoliTable<mEdge>::Entry) << " bytes (aligned "
-              << alignof(ToffoliTable<mEdge>::Entry) << " bytes)"
               << "\n  Package size: " << sizeof(Package) << " bytes (aligned "
               << alignof(Package) << " bytes)"
               << "\n"
@@ -3725,8 +3713,6 @@ template <class Config> class Package {
     vectorKronecker.printStatistics();
     std::cout << "[CT Matrix Kronecker] ";
     matrixKronecker.printStatistics();
-    std::cout << "[Toffoli Table] ";
-    toffoliTable.printStatistics();
     std::cout << "[Stochastic Noise Table] ";
     stochasticNoiseOperationCache.printStatistics();
     std::cout << "[CT Density Add] ";

test/dd/test_package.cpp

@@ -435,36 +435,6 @@ TEST(DDPackageTest, TestConsistency) {
   dd->debugnode(bellState.p);
 }
 
-TEST(DDPackageTest, ToffoliTable) {
-  auto dd = std::make_unique<dd::Package<>>(4);
-
-  // try to search for a toffoli in an empty table
-  auto toffoli = dd->toffoliTable.lookup(3, {0_nc, 1_pc}, 2);
-  EXPECT_EQ(toffoli.p, nullptr);
-  if (toffoli.p == nullptr) {
-    toffoli = dd->makeGateDD(dd::Xmat, 3, {0_nc, 1_pc}, 2);
-    dd->toffoliTable.insert(3, {0_nc, 1_pc}, 2, toffoli);
-  }
-
-  // try again with same toffoli
-  auto toffoliTableEntry = dd->toffoliTable.lookup(3, {0_nc, 1_pc}, 2);
-  EXPECT_NE(toffoliTableEntry.p, nullptr);
-  EXPECT_EQ(toffoli, toffoliTableEntry);
-
-  // try again with different controlled toffoli
-  toffoliTableEntry = dd->toffoliTable.lookup(3, {0_pc, 1_pc}, 2);
-  EXPECT_EQ(toffoliTableEntry.p, nullptr);
-
-  // try again with different qubit toffoli
-  toffoliTableEntry = dd->toffoliTable.lookup(4, {0_pc, 1_pc, 2_pc}, 3);
-  EXPECT_EQ(toffoliTableEntry.p, nullptr);
-
-  // clear the table
-  dd->toffoliTable.clear();
-  toffoliTableEntry = dd->toffoliTable.lookup(3, {0_nc, 1_pc}, 2);
-  EXPECT_EQ(toffoliTableEntry.p, nullptr);
-}
-
 TEST(DDPackageTest, Extend) {
   auto dd = std::make_unique<dd::Package<>>(4);