Method BuildIfElse

cpp/src/gandiva/llvm_generator.cc:1174–1233

}

LValuePtr LLVMGenerator::Visitor::BuildIfElse(llvm::Value* condition,
                                              std::function<LValuePtr()> then_func,
                                              std::function<LValuePtr()> else_func,
                                              DataTypePtr result_type) {
  llvm::IRBuilder<>* builder = ir_builder();
  llvm::LLVMContext* context = generator_->context();
  LLVMTypes* types = generator_->types();

  // Create blocks for the then, else and merge cases.
  llvm::BasicBlock* then_bb = llvm::BasicBlock::Create(*context, "then", function_);
  llvm::BasicBlock* else_bb = llvm::BasicBlock::Create(*context, "else", function_);
  llvm::BasicBlock* merge_bb = llvm::BasicBlock::Create(*context, "merge", function_);

  builder->CreateCondBr(condition, then_bb, else_bb);

  // Emit the then block.
  builder->SetInsertPoint(then_bb);
  LValuePtr then_lvalue = then_func();
  builder->CreateBr(merge_bb);

  // refresh then_bb for phi (could have changed due to code generation of then_vv).
  then_bb = builder->GetInsertBlock();

  // Emit the else block.
  builder->SetInsertPoint(else_bb);
  LValuePtr else_lvalue = else_func();
  builder->CreateBr(merge_bb);

  // refresh else_bb for phi (could have changed due to code generation of else_vv).
  else_bb = builder->GetInsertBlock();

  // Emit the merge block.
  builder->SetInsertPoint(merge_bb);
  auto llvm_type = types->IRType(result_type->id());
  llvm::PHINode* result_value = builder->CreatePHI(llvm_type, 2, "res_value");
  result_value->addIncoming(then_lvalue->data(), then_bb);
  result_value->addIncoming(else_lvalue->data(), else_bb);

  LValuePtr ret;
  switch (result_type->id()) {
    case arrow::Type::STRING:
    case arrow::Type::BINARY: {
      llvm::PHINode* result_length;
      result_length = builder->CreatePHI(types->i32_type(), 2, "res_length");
      result_length->addIncoming(then_lvalue->length(), then_bb);
      result_length->addIncoming(else_lvalue->length(), else_bb);
      ret = std::make_shared<LValue>(result_value, result_length);
      break;
    }

    case arrow::Type::DECIMAL:
      ret = generator_->BuildDecimalLValue(result_value, result_type);
      break;

    default:
      ret = std::make_shared<LValue>(result_value);
      break;
  }