InternalCompilerError: Invalid stack item name: slot with --via-ir

[Vectorized]

Description

Compiler gives an error InternalCompilerError: Invalid stack item name: slot when compiling with --via-ir,
when an assembly block calls .slot on a reference to a mapping.

Environment

• Compiler version: 0.8.15

Steps to Reproduce

Found in ERC721A, when compiling with --via-ir

function _getApprovedAddress(uint256 tokenId)
    private
    view
    returns (uint256 approvedAddressSlot, address approvedAddress)
{
    mapping(uint256 => address) storage tokenApprovalsPtr = _tokenApprovals;
    // The following is equivalent to `approvedAddress = _tokenApprovals[tokenId]`.
    assembly {
        // Compute the slot.
        mstore(0x00, tokenId)
        mstore(0x20, tokenApprovalsPtr.slot) // This line causes the compiler error.
        approvedAddressSlot := keccak256(0x00, 0x40)
        // Load the slot's value from storage.
        approvedAddress := sload(approvedAddressSlot)
    }
}

The code compiles normally without --via-ir.

See: chiru-labs/ERC721A#364

[Vectorized]

Issue already opened.

Please refer to #13259