llvm dev - Apr 2009 - [LLVMdev] Iterating over all uses of a Function

Hi,

I try to iterate over all uses of a Function with the following
code (simplified):

for (Value::use_iterator UI = F->use_begin(), UE = F->use_end();
                         UI != UE; ++UI) {

    if (CallInst* I = dyn_cast<CallInst>(*UI)) {
    // do something interesting
    }
}
 
This works on Linux, but on Windows the dyn_cast fails, even
though the only use of F in that module is a 'call'. However,
dyn_cast<Instruction>(*UI) works, and returns a pointer
to "<Invalid operator>" instruction.

Is this a bug or am I doing something incorrectly?

Hi Mikhail,

Can you please attach a simple .bc file that is subject to this problem?

Anthony

On Apr 21, 2009, at 7:33 AM, Mikhail Glushenkov wrote:
> Hi,
>
> I try to iterate over all uses of a Function with the following
> code (simplified):
>
> for (Value::use_iterator UI = F->use_begin(), UE = F->use_end();
>                         UI != UE; ++UI) {
>
>    if (CallInst* I = dyn_cast<CallInst>(*UI)) {
>    // do something interesting
>    }
> }
>
> This works on Linux, but on Windows the dyn_cast fails, even
> though the only use of F in that module is a 'call'. However,
> dyn_cast<Instruction>(*UI) works, and returns a pointer
> to "<Invalid operator>" instruction.
>
> Is this a bug or am I doing something incorrectly?
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

On Apr 21, 2009, at 4:33 AM, Mikhail Glushenkov wrote:
> Hi,
>
> I try to iterate over all uses of a Function with the following
> code (simplified):
This should work.  Perhaps you have a memory stomper problem?

-Chris
>
>
> for (Value::use_iterator UI = F->use_begin(), UE = F->use_end();
>                         UI != UE; ++UI) {
>
>    if (CallInst* I = dyn_cast<CallInst>(*UI)) {
>    // do something interesting
>    }
> }
>
> This works on Linux, but on Windows the dyn_cast fails, even
> though the only use of F in that module is a 'call'. However,
> dyn_cast<Instruction>(*UI) works, and returns a pointer
> to "<Invalid operator>" instruction.
>
> Is this a bug or am I doing something incorrectly?
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

Chris Lattner <clattner <at> apple.com> writes:
> This should work.  Perhaps you have a memory stomper problem?
Then I guess that this is a bug. I wrote a simple test pass
that exhibits this behaviour, and also manages to crash opt:

http://llvm.org/bugs/show_bug.cgi?id=4028

Hi Anthony,
> Can you please attach a simple .bc file that is subject to this
> problem?
See http://llvm.org/bugs/show_bug.cgi?id=4028

This is generated from the following C code:

void interesting_function();

int main() {
  interesting_function();
}

I use the SVN version of LLVM, built with current MinGW (3.4.5).