Question

I’ve got yet another error trying to compile with Apple GCC 4.2.1 using the -fasm-blocks argument (which enables Intel style assembly syntax) inline assembly code which worked in MSVC: block assembly operand not recognized, label ‘LASM$TYPE’ used but not defined:

typedef struct _MyStruct
{
    int data;
    //...
}MyStruct;

void testAsm()
{
    MyStruct *pMyStruct = new MyStruct(); // Please not that I create an instance of MyStruct here only for the sake of simplicity

    _asm
    {
        mov edi, pMyStruct
        add edi, TYPE MyStruct // error: block assembly operand not recognized. label 'LASM$TYPE' used but not defined
        //...
    };

    delete pMyStruct;
}

How can I fix this problem?

Answer 1

TYPE is an MSVC-specific asm keyword. Here it just means sizeof. I tried to find some gcc asm-block documentation on the web, but I gave up after ten minutes. Try

add edi,sizeof(MyStruct)

and variants. I don’t have an Apple, so I can’t try it out for you.

Updated to answer question in comment: Try this:

add edi,__offsetof(MyStruct,MyMember)

If it doesn’t work, see “Using the GNU Compiler Collection” for documentation.