[LLVMdev] how to reslove gcc_except_table?

[Duncan Sands]

Hi,

>     maybe this should not be here!

does this have anything to do with LLVM?

> int main()
> {
>     try {
>         throw 34;
>     }
>     catch (int) {
>     }
>     catch (char) {
>     }
>     catch (bool) {
>     }
> }

The action is 0x5, this refers to

    123          .byte   0x3
    124          .byte   0x7d

where 0x3 means that the typeinfo is _ZTIi (int).
The 0x7d says that if the typeinfo doesn't match,
then the next action to consider is at offset -3
from here.  In other words, it will continue with

    121          .byte   0x2
    122          .byte   0x7d

i.e. it will then try and match with _ZTIc.  If this
doesn't match then the next action to consider is
offset -3 from here (0x7d), i.e. it will next examine

    119          .byte   0x1     # Action record table
    120          .byte   0x0

i.e. it will try and match with _ZTIb.  If this
doesn't match then it is all over (0x0).

>    116          .uleb128 0x0    # region 0 landing pad
>    117          .uleb128 0x5    # action
>    118  .LLSDACSE2:
>    119          .byte   0x1     # Action record table
>    120          .byte   0x0
>    121          .byte   0x2
>    122          .byte   0x7d
>    123          .byte   0x3
>    124          .byte   0x7d
>    125          .align 4
>    126          .long   _ZTIi
>    127          .long   _ZTIc
>    128          .long   _ZTIb
>    129  .LLSDATT2:
> 
> 
> ok: my problem is the action(line 117) how to index to the action record table?
>       in Action record table , why there are the magic 0x7d?.

Ciao,

Duncan.