llvm dev - Feb 2010 - [LLVMdev] How to check if an Instruction is still in a Function

Hi,

Given an instruction ptr instr, and a Function ptr func,
can I simply check if func == instr->get_parent()->get_parent() to see if
this instruction is still in this Function?

We can also look up this instruction in the blocks of this function.
But this may take more time.

Thanks.
-- 
Jianzhou

On Feb 28, 2010, at 11:11 AM, Jianzhou Zhao wrote:
> Hi,
> 
> Given an instruction ptr instr, and a Function ptr func,
> can I simply check if func == instr->get_parent()->get_parent() to
see if
> this instruction is still in this Function?
> 
Yup!

-bw

On Mon, Mar 1, 2010 at 7:29 PM, Bill Wendling <wendling at apple.com>
wrote:
> On Feb 28, 2010, at 11:11 AM, Jianzhou Zhao wrote:
>
>> Hi,
>>
>> Given an instruction ptr instr, and a Function ptr func,
>> can I simply check if func == instr->get_parent()->get_parent()
to see if
>> this instruction is still in this Function?
>>
> Yup!
Well. I just found that this is not quite safe sometimes.
After an instruction is removed via 'eraseFromParent',
the instruction will be deleted, and become 'dangling'.
LLVM does not set this removed instruction as NULL.
In this case, instr->get_parent()->get_parent() gives
me 'seq fault'.
>
> -bw
>
>


-- 
Jianzhou