llvm dev - Sep 2011 - [LLVMdev] constantexpr problem

Hi all,
   I have got a problem when I used the use_empty() member function while I
used a global variable. I erase all the instructions which will use a global
variable. Then I called the use_empty() on that global variable. I got no
empty because a constantexpr use the global variable. I wonder whether there
is any way to erase the constantexpr which is useless to me but occupying
the global variable.
  best regard!

                                                  yours. Tsingray
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Hi Tsingray,
>     I have got a problem when I used the use_empty() member function while
I
> used a global variable. I erase all the instructions which will use a
global
> variable. Then I called the use_empty() on that global variable. I got no
empty
> because a constantexpr use the global variable. I wonder whether there is
any
> way to erase the constantexpr which is useless to me but occupying the
global
> variable.
if G is your global variable, do
   G->replaceAllUsesWith(UndefValue::get(G->getType()));
to replace G with undef in all users of G.  You can then safely delete G.

Ciao, Duncan.

On 09/23/2011 07:27 AM, tsingray liu wrote:
> Hi all,
>     I have got a problem when I used the use_empty() member function
> while I used a global variable. I erase all the instructions which will
> use a global variable. Then I called the use_empty() on that global
> variable. I got no empty because a constantexpr use the global variable.
> I wonder whether there is any way to erase the constantexpr which is
> useless to me but occupying the global variable.
>    best regard!
GV->removeDeadConstantUsers();

Nick