Commit e853ddd2 authored by Nguyen, Thien Minh's avatar Nguyen, Thien Minh
Browse files

Fixed a bug in single-qubit gate merge pass 



Need to handle the case whereby the whole sequence is canceled, e.g. h-x-h-z, etc.

Signed-off-by: default avatarThien Nguyen <nguyentm@ornl.gov>
parent 314bacea

mlir/parsers/qasm3/tests/test_optimization.cpp

+42 −0
Original line number Diff line number Diff line
@@ -54,6 +54,48 @@ rz(2.4566) q[1]; 
  EXPECT_EQ(countSubstring(llvm, "__quantum__qis__rz"), 1);

}



TEST(qasm3PassManagerTester, checkSingleQubitGateMergeOpt) {

  // Merge to X == rx(pi)

  const std::string src = R"#(OPENQASM 3;

include "qelib1.inc";

qubit q[2];

h q[0];

z q[0];

h q[0];

)#";

  auto llvm =

      qcor::mlir_compile("qasm3", src, "test_kernel", qcor::OutputType::LLVMIR, false);

  std::cout << "LLVM:\n" << llvm << "\n";

  

  // Get the function LLVM only (not __internal_mlir_XXXX, etc.)

  llvm = llvm.substr(llvm.find("@test_kernel"));

  // 1 instrucions left: rx 

  EXPECT_EQ(countSubstring(llvm, "__quantum__qis"), 1);

  EXPECT_EQ(countSubstring(llvm, "__quantum__qis__rx"), 1);

}



TEST(qasm3PassManagerTester, checkRemoveUnusedQirCalls) {

  // Complete cancellation => remove extract and qalloc as well

  const std::string src = R"#(OPENQASM 3;

include "qelib1.inc";

qubit q[2];

h q[0];

z q[0];

h q[0];

x q[0];

cx q[0], q[1];

cx q[0], q[1];

)#";

  auto llvm =

      qcor::mlir_compile("qasm3", src, "test_kernel", qcor::OutputType::LLVMIR, false);

  std::cout << "LLVM:\n" << llvm << "\n";

  // No gates, extract, or alloc/dealloc:

  EXPECT_EQ(countSubstring(llvm, "__quantum__qis"), 0);

  EXPECT_EQ(countSubstring(llvm, "__quantum__rt__array_get_element_ptr_1d"), 0);

  EXPECT_EQ(countSubstring(llvm, "__quantum__rt__qubit_allocate_array"), 0);

  EXPECT_EQ(countSubstring(llvm, "__quantum__rt__qubit_release_array"), 0);

}



int main(int argc, char **argv) {

  ::testing::InitGoogleTest(&argc, argv);

  auto ret = RUN_ALL_TESTS();

mlir/transforms/optimizations/SingleQubitGateMergingPass.cpp

+11 −3
Original line number Diff line number Diff line
@@ -133,9 +133,17 @@ void SingleQubitGateMergingPass::runOnOperation() { 


        // Input -> Output mapping (this instruction is to be removed)

        auto last_inst_orig = ops_list.back();

        if (new_ops.empty()) {

          auto first_inst_orig = ops_list.front();

          // The new sequence is empty (complete cancellation)

          // Map input to output of the whole sequence.

          (*last_inst_orig.result_begin())

              .replaceAllUsesWith(first_inst_orig.getOperand(0));

        } else {

          auto last_inst_new = new_ops.back();

          (*last_inst_orig.result_begin())

              .replaceAllUsesWith(*last_inst_new.result_begin());

        }



        // Erase original instructions:

        for (auto &op_to_delete : ops_list) {