llvm dev - Jul 2013 - [LLVMdev] Steps to addDestination

Hi,
I need to addDestination to some basic blocks
I used the following code


 Value* Address;
  IndirectBrInst *IBI = IndirectBrInst::Create(Address,
Result.size(),i->getTerminator() );

IBI->addDestination(i);

The following error was issued

void llvm::IndirectBrInst::init(llvm::Value *, unsigned int): Assertion
`Address && Address->getType()->isPointerTy() &&
"Address of indirectbr
must be a pointer"' failed.


I need to know the steps to add new indirect branch to a basic block with
this method

-- 
*Rasha Salah Omar
Msc Student at E-JUST
Demonestrator  at Faculty of Computers and Informatics
Benha University
*
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Hi Rasha,
> I need to addDestination to some basic blocks
Just to make sure there's no confusion here: you really are trying to
create code like:

define i32 @foo(i1 %tst) {
  %Address = select i1 %tst, i8* blockaddress(@foo, %true), i8*
blockaddress(@foo, %false)
  indirectbr i8* %Address, [label %true, label %false] ; This is what
you're creating
true:
  ret i32 42
false:
  ret i32 0
}

and not:

define i32 @bar(i1 %tst) {
  br i1 %tst, label %true, label %false ; You're not trying to create this
true:
  ret i32 42
false:
  ret i32 0
}

If that's incorrect, you're going about it entirely the wrong way. We
can help with either, but it's best not to go too far on a
misunderstanding.
>  Value* Address;
>   IndirectBrInst *IBI = IndirectBrInst::Create(Address,
Result.size(),i->getTerminator() );
>
> IBI->addDestination(i);
The problem seems to be that "Address" is uninitialised but it needs
to be set to some valid pointer value before creating your IndirectBr.
To replicate my first example it would be set to the "select"
instruction, for example; whatever produces your testination
blockaddress.

Cheers.

Tim.

1- I need the first example.
2- I set the Address uninitialized according to the documentation
" Setting the name on the Value automatically updates the module's
symbol
table"
from Value.h source code
3- I'm not sure about "select" instruction, you mean that the
address is
the new destination (basic block)that will be added
Thanks


On 23 July 2013 16:38, Tim Northover <t.p.northover at gmail.com> wrote:
> Hi Rasha,
>
> > I need to addDestination to some basic blocks
>
> Just to make sure there's no confusion here: you really are trying to
> create code like:
>
> define i32 @foo(i1 %tst) {
>   %Address = select i1 %tst, i8* blockaddress(@foo, %true), i8*
> blockaddress(@foo, %false)
>   indirectbr i8* %Address, [label %true, label %false] ; This is what
> you're creating
> true:
>   ret i32 42
> false:
>   ret i32 0
> }
>
> and not:
>
> define i32 @bar(i1 %tst) {
>   br i1 %tst, label %true, label %false ; You're not trying to create
this
> true:
>   ret i32 42
> false:
>   ret i32 0
> }
>
> If that's incorrect, you're going about it entirely the wrong way.
We
> can help with either, but it's best not to go too far on a
> misunderstanding.
>
> >  Value* Address;
> >   IndirectBrInst *IBI = IndirectBrInst::Create(Address,
> Result.size(),i->getTerminator() );
> >
> > IBI->addDestination(i);
>
> The problem seems to be that "Address" is uninitialised but it
needs
> to be set to some valid pointer value before creating your IndirectBr.
> To replicate my first example it would be set to the "select"
> instruction, for example; whatever produces your testination
> blockaddress.
>
> Cheers.
>
> Tim.
>


-- 
*Rasha Salah Omar
Msc Student at E-JUST
Demonestrator  at Faculty of Computers and Informatics
Benha University
*
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