llvm dev - Mar 2018 - Change function call name in a CallInst only in certain functions

Hello,

In my module I have functions:

a
b
c
f3 calls "a"
f2 calls "a"
f1 calls "b"

I would like to modify a CallInst in the f2. Now it calls "a", but I
want
changed it to "c".

When loop over the instructions of the  f2, I can get a CallInst to be
modified, then I use "setName" to changed it to "c".


Problem is, since references are updated, "a" is changed to
"c" even in f1.

Any solution?

Thanks
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Not sure why you are using setName here. I personally use CallSite() to wrap
InvokeInst and CallInst, then use CallSite::setCalledFunction for this kind of
stuff.
Zhang
> On 23 Mar 2018, at 23:07, Dávid Bolvanský via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> Hello,
>  
> In my module I have functions:
> 
> a
> b
> c
> f3 calls "a"
> f2 calls "a"
> f1 calls "b"
> 
> I would like to modify a CallInst in the f2. Now it calls "a",
but I want changed it to "c".
> 
> When loop over the instructions of the  f2, I can get a CallInst to be
modified, then I use "setName" to changed it to "c".
> 
> 
> Problem is, since references are updated, "a" is changed to
"c" even in f1.
> 
> Any solution?
> 
> Thanks
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

You are probably calling setName() on the called Function, which in-turned
renamed the called Function instead of replacing the called function.
Depending on your use-case, if you are certain that you only need to modify
CallInsts, then you could simply call CallInst::setCalledFunction , otherwise
it’s probably wiser to use CallSite as a wrapper for both CallInst and
InvokeInst. Do note, however, that no matter which solution you end up using,
you’ll need to update the FunctionType as well
Zhang
> On 23 Mar 2018, at 23:07, Dávid Bolvanský via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> Hello,
>  
> In my module I have functions:
> 
> a
> b
> c
> f3 calls "a"
> f2 calls "a"
> f1 calls "b"
> 
> I would like to modify a CallInst in the f2. Now it calls "a",
but I want changed it to "c".
> 
> When loop over the instructions of the  f2, I can get a CallInst to be
modified, then I use "setName" to changed it to "c".
> 
> 
> Problem is, since references are updated, "a" is changed to
"c" even in f1.
> 
> Any solution?
> 
> Thanks
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

Okey, setCalledFunction is useful. But I have a problem since my "a",
"b",
"c" are functions from libc, not my defined ones in the module.

if (CallInst *call_inst = dyn_cast<CallInst>(&I)) {

          Function *fn = call_inst->getCalledFunction();
          if (fn->getName() == "a") {
            ValueToValueMapTy map;
            FN = CloneFunction(fn, map, nullptr);
            FN->setName("c");
            call_inst->setCalledFunction(FN);
          }
          ...
}


I get "Assertion `!NodePtr->isKnownSentinel()' failed."


2018-03-24 1:19 GMT+01:00 mayuyu.io <admin at mayuyu.io>:
>
> You are probably calling setName() on the called Function, which in-turned
> renamed the called Function instead of replacing the called function.
> Depending on your use-case, if you are certain that you only need to
> modify CallInsts, then you could simply call CallInst::setCalledFunction ,
> otherwise it’s probably wiser to use CallSite as a wrapper for both
> CallInst and InvokeInst. Do note, however, that no matter which solution
> you end up using, you’ll need to update the FunctionType as well
> Zhang
>
> > On 23 Mar 2018, at 23:07, Dávid Bolvanský via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
> >
> > Hello,
> >
> > In my module I have functions:
> >
> > a
> > b
> > c
> > f3 calls "a"
> > f2 calls "a"
> > f1 calls "b"
> >
> > I would like to modify a CallInst in the f2. Now it calls
"a", but I
> want changed it to "c".
> >
> > When loop over the instructions of the  f2, I can get a CallInst to be
> modified, then I use "setName" to changed it to "c".
> >
> >
> > Problem is, since references are updated, "a" is changed to
"c" even in
> f1.
> >
> > Any solution?
> >
> > Thanks
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
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