Commit 3b69a4ff authored by Nguyen, Thien Minh's avatar Nguyen, Thien Minh
Browse files

Added the pass to remove consecutive reset ops 



2 resets -> just need to keep 1.

Signed-off-by: default avatarThien Nguyen <nguyentm@ornl.gov>
parent ddf60396

mlir/parsers/qasm3/tests/test_optimization.cpp

+24 −0
Original line number Diff line number Diff line
@@ -32,6 +32,30 @@ cx q[0], q[1]; 
  EXPECT_TRUE(llvm.find("__quantum__qis") == std::string::npos);

}



TEST(qasm3PassManagerTester, checkResetSimplification) {

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

include "qelib1.inc";

qubit q[2];



reset q[0];

x q[1];

reset q[0];

)#";

  auto llvm =

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

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



  // Get the main kernel section only

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

  const auto last = llvm.find_first_of("}");

  llvm = llvm.substr(0, last + 1);

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

  // One reset and one X:

  EXPECT_EQ(countSubstring(llvm, "__quantum__qis"), 2);

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

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

}



TEST(qasm3PassManagerTester, checkRotationMerge) {

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

include "qelib1.inc";

mlir/transforms/optimizations/IdentityPairRemovalPass.cpp

+43 −0
Original line number Diff line number Diff line
@@ -130,4 +130,47 @@ void CNOTIdentityPairRemovalPass::runOnOperation() { 
    op.erase();

  }

}



void DuplicateResetRemovalPass::getDependentDialects(

    DialectRegistry &registry) const {

  registry.insert<LLVM::LLVMDialect>();

}



void DuplicateResetRemovalPass::runOnOperation() {

  // Walk the operations within the function.

  std::vector<mlir::quantum::ValueSemanticsInstOp> deadOps;

  getOperation().walk([&](mlir::quantum::ValueSemanticsInstOp op) {

    if (std::find(deadOps.begin(), deadOps.end(), op) != deadOps.end()) {

      // Skip this op since it was deleted (forward search)

      return;

    }

    auto inst_name = op.name();

    

    if (inst_name != "reset") {

      return;

    }



    auto return_value = *op.result().begin();

    if (return_value.hasOneUse()) {

      // get that one user

      auto user = *return_value.user_begin();

      // cast to a inst op

      if (auto next_inst =

              dyn_cast_or_null<mlir::quantum::ValueSemanticsInstOp>(user)) {

        if (next_inst.name().str() == "reset") {

          // Two resets in a row:

          // Chain the input -> output and mark this second reset to delete:

          (*next_inst.result_begin())

              .replaceAllUsesWith(next_inst.getOperand(0));

          deadOps.emplace_back(next_inst);

        }

      }

    }

  });



  for (auto &op : deadOps) {

    op->dropAllUses();

    op.erase();

  }

}

} // namespace qcor

mlir/transforms/optimizations/IdentityPairRemovalPass.hpp

+9 −0
Original line number Diff line number Diff line
@@ -29,4 +29,13 @@ struct CNOTIdentityPairRemovalPass 
  void runOnOperation() final;

  CNOTIdentityPairRemovalPass() {}

};



// Remove duplicate reset:

// 2 consecutive resets on a single qubit line => remove one.

struct DuplicateResetRemovalPass

    : public PassWrapper<DuplicateResetRemovalPass, OperationPass<ModuleOp>> {

  void getDependentDialects(DialectRegistry &registry) const override;

  void runOnOperation() final;

  DuplicateResetRemovalPass() {}

};

} // namespace qcor
 
 No newline at end of file

mlir/transforms/pass_manager.hpp

+2 −1
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ void configureOptimizationPasses(mlir::PassManager &passManager) { 
    // Simple Identity pair removals

    passManager.addPass(std::make_unique<SingleQubitIdentityPairRemovalPass>());

    passManager.addPass(std::make_unique<CNOTIdentityPairRemovalPass>());

    passManager.addPass(std::make_unique<DuplicateResetRemovalPass>());

    

    // Rotation merging

    passManager.addPass(std::make_unique<RotationMergingPass>());