Re: [BC ABI] Type assertions

[Bryce McKinlay <mckinlay at redhat dot com>]

Andrew Haley wrote:

> This patch adds type assertions to the ouput generated by gcj when
> compiling with -findirect-dispatch.  
>
> There's a new field, Class.verify, which points to executable code.
> When a class is loaded, this code is called.  In turn, this calls
> _Jv_CheckAssignment for every assertion.
>
> Bryce has pointed out that this would be much more space efficient
> with a table of {source, dest} pairs.  While true, if this were the
> only assertion form it would preclude more complex assertions, and I
> want to leave that possibility open for a little while.
>  
If it turns out we need other kinds of type assertions, the table could 
be in a form like:

struct assertion_table_entry
{
 int opcode;
 utf8const operand_a;
 utf8const operand_b;
}

Where the opcode can be eg: types_compatable, is_interface, etc.

Bryce