Yul stack check (possible) bug

gistfile1.txt

    code {
        function memcpy_384(dst, src)
        {
            let hi := mload(src)
            let lo := mload(add(src, 32))
            mstore(dst, hi)
            mstore(add(dst, 32), lo)
        }
        function f2m_add(x_0, x_1, y_0, y_1, r_0, r_1, modulus)
        {
            memcpy_384(r_0, x_0)
            memcpy_384(r_1, x_1)
            addmod384(r_0, y_0, modulus)
            addmod384(r_1, y_1, modulus)
        }
        function f2m_sub(x_0, x_1, y_0, y_1, r_0, r_1, modulus)
        {
            memcpy_384(r_0, x_0)
            memcpy_384(r_1, x_1)
            submod384(r_0, y_0, modulus)
            submod384(r_1, y_1, modulus)
        }
        function f2m_mul(x_0_offset, x_1_offset, y_0_offset, y_1_offset, r_0, r_1, modulus, inv, mem)
        {
            let A := mem
            let B := add(mem, 64)
            let C := add(B, 64)
            let D := add(C, 64)
            memcpy_384(A, x_0_offset)
            mulmodmont384(A, y_0_offset, modulus, inv)
            memcpy_384(B, x_1_offset)
            mulmodmont384(B, y_1_offset, modulus, inv)
            memcpy_384(C, x_0_offset)
            addmod384(C, x_1_offset, modulus)
            memcpy_384(D, y_0_offset)
            addmod384(D, y_1_offset, modulus)
            mulmodmont384(C, D, modulus, inv)
            mstore(x_0_offset, 0x0000000000000000000000000000000000000000000000000000000000000000)
            mstore(add(x_0_offset, 32), 0x0000000000000000000000000000000000000000000000000000000000000000)
            submod384(r_0, B, modulus)
            addmod384(B, A, modulus)
            submod384(C, B, modulus)
            memcpy_384(r_1, C)
        }
        function f6m_mul(x, y, r, inv, modulus)
        {
            let mem_end := msize()
            let aA_0 := mem_end
            let aA_1 := add(aA_0, 64)
:Exception while assembling: /solidity/libyul/backends/evm/EVMCodeTransform.cpp(600): Throw in function void solidity::yul::CodeTransform::operator()(const solidity::yul::Block&)
Dynamic exception type: boost::wrapexcept<solidity::yul::StackTooDeepError>
std::exception::what: Variable y is 1 slot(s) too deep inside the stack.
[solidity::util::tag_comment*] = Variable y is 1 slot(s) too deep inside the stack.