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Qiuping Yi via llvm-dev

2016-Jan-20 06:33 UTC

[llvm-dev] Why getFunction() of CallGraphNode return NULL function?

So, I won't know the called function statically, Right?


--------------------------------------------
Qiuping Yi
Institute Of Software
Chinese Academy of Sciences

On Wed, Jan 20, 2016 at 2:24 PM, Nema, Ashutosh <Ashutosh.Nema at amd.com>
wrote:
> Typically for C++ virtual function you will see an indirect callSite
> (unless not de-virtualized).
>
>
>
> Regards,
>
> Ashutosh
>
>
>
> *From:* Qiuping Yi [mailto:yiqiuping at gmail.com]
> *Sent:* Wednesday, January 20, 2016 9:10 AM
> *To:* Nema, Ashutosh
> *Cc:* llvm-dev
> *Subject:* Re: [llvm-dev] Why getFunction() of CallGraphNode return NULL
> function?
>
>
>
> Dear Ashutosh,
>
>
>
> Thank you, I can handle some indirect callSites by getFunction() of
> InvokInst and CallInst.
>
>
>
> However, when I am handling C++ programs, I found the calls of member
> functions are converted
>
> to some strange  indirect calls. For example:
>
>
>
> table->truncate(sysTransaction);   // from mysql
>
>
>
> are translated to the next complex llvm IR:
>
>
>
> _ZN8Database20getSystemTransactionEv.exit:        ; preds = %bb33
>
>   call void @llvm.dbg.value(metadata %class.Transaction.553* %tmp36, i64
> 0, metadata !7310, metadata !53545), !dbg !69981
>
>   %tmp37 = bitcast %class.Table.543* %table to void (%class.Table.543*,
> %class.Transaction.553*)***, !dbg !69982
>
>   %tmp38 = load void (%class.Table.543*, %class.Transaction.553*)***
> %tmp37, align 8, !dbg !69982, !tbaa !53550
>
>   %tmp39 = getelementptr inbounds void (%class.Table.543*,
> %class.Transaction.553*)** %tmp38, i64 5, !dbg !69982
>
>   %tmp40 = load void (%class.Table.543*, %class.Transaction.553*)**
> %tmp39, align 8, !dbg !69982
>
>   invoke void %tmp40(%class.Table.543* %table, %class.Transaction.553*
> %tmp36)
>
>           to label %bb41 unwind label %bb72, !dbg !69982
>
>
>
> and thus I cannot find the called function "truncate" from
"invoke void
> %tmp40(...)", what should I do?
>
> I didn't analysis C++ code with llvm, does all the function calls
through
> objects are translated to such complex indirect calls?
>
> If so, how can I dereference such functions? Thanks!
>
>
>
>
>
> --------------------------------------------
> Qiuping Yi
> Institute Of Software
> Chinese Academy of Sciences
>
>
>
> On Tue, Jan 19, 2016 at 8:23 PM, Nema, Ashutosh <Ashutosh.Nema at
amd.com>
> wrote:
>
> You will see NULL for indirect callSite.
>
> May need to add additional checks for this possibility.
>
>
>
> Regards,
>
> Ashutosh
>
>
>
> *From:* llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] *On Behalf Of
*Qiuping
> Yi via llvm-dev
> *Sent:* Tuesday, January 19, 2016 5:35 PM
> *To:* llvm-dev at lists.llvm.org
> *Subject:* [llvm-dev] Why getFunction() of CallGraphNode return NULL
> function?
>
>
>
> Hi all,
>
>
>
> I want to find all the called functions in each function, thus I iterate
> the calledFunctions of each CallGraphNode in CallGraph as follow:
>
>
>
> for (CallGraph::iterator it = CG->begin(); it != CG->end(); ++it) {
>
>    CallGraphNode* node = it->second;
>
>    for (CallGraphNode::iterator it2 = node->begin(); it2 !=
node->end();
> ++it2) {
>
>       Function* calledFunc = it2->second=>getFunction();
>
>       cerr << ”function: “ << calledFunc->getName().str()
<<"\n";  *//
> crash some times*
>
>       ... ...
>
>       ... ...
>
>     }
>
> }
>
>
>
> I found that some time "calledFunc" is NULL function and thus the
output
> crash. I don't known why? If the before code is wrong, so what is the
> correct method for get all the called functions?
>
>
>
> I use LLVM 3.6. Thank you all in advance.
>
>
> --------------------------------------------
> Qiuping Yi
> Institute Of Software
> Chinese Academy of Sciences
>
>
>-------------- next part --------------
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Nema, Ashutosh via llvm-dev

2016-Jan-20 06:38 UTC

head link

[llvm-dev] Why getFunction() of CallGraphNode return NULL function?

For indirect callSite it’s hard to know the target(or actual) function
statically because there can be multiple possibilities.

Regards,
Ashutosh

From: Qiuping Yi [mailto:yiqiuping at gmail.com]
Sent: Wednesday, January 20, 2016 12:03 PM
To: Nema, Ashutosh
Cc: llvm-dev
Subject: Re: [llvm-dev] Why getFunction() of CallGraphNode return NULL function?

So, I won't know the called function statically, Right?

--------------------------------------------
Qiuping Yi
Institute Of Software
Chinese Academy of Sciences

On Wed, Jan 20, 2016 at 2:24 PM, Nema, Ashutosh <Ashutosh.Nema at
amd.com<mailto:Ashutosh.Nema at amd.com>> wrote:
Typically for C++ virtual function you will see an indirect callSite (unless not
de-virtualized).

Regards,
Ashutosh

From: Qiuping Yi [mailto:yiqiuping at gmail.com<mailto:yiqiuping at
gmail.com>]
Sent: Wednesday, January 20, 2016 9:10 AM
To: Nema, Ashutosh
Cc: llvm-dev
Subject: Re: [llvm-dev] Why getFunction() of CallGraphNode return NULL function?

Dear Ashutosh,

Thank you, I can handle some indirect callSites by getFunction() of InvokInst
and CallInst.

However, when I am handling C++ programs, I found the calls of member functions
are converted
to some strange  indirect calls. For example:

table->truncate(sysTransaction);   // from mysql

are translated to the next complex llvm IR:

_ZN8Database20getSystemTransactionEv.exit:        ; preds = %bb33
  call void @llvm.dbg.value(metadata %class.Transaction.553* %tmp36, i64 0,
metadata !7310, metadata !53545), !dbg !69981
  %tmp37 = bitcast %class.Table.543* %table to void (%class.Table.543*,
%class.Transaction.553*)***, !dbg !69982
  %tmp38 = load void (%class.Table.543*, %class.Transaction.553*)*** %tmp37,
align 8, !dbg !69982, !tbaa !53550
  %tmp39 = getelementptr inbounds void (%class.Table.543*,
%class.Transaction.553*)** %tmp38, i64 5, !dbg !69982
  %tmp40 = load void (%class.Table.543*, %class.Transaction.553*)** %tmp39,
align 8, !dbg !69982
  invoke void %tmp40(%class.Table.543* %table, %class.Transaction.553* %tmp36)
          to label %bb41 unwind label %bb72, !dbg !69982

and thus I cannot find the called function "truncate" from
"invoke void %tmp40(...)", what should I do?
I didn't analysis C++ code with llvm, does all the function calls through
objects are translated to such complex indirect calls?
If so, how can I dereference such functions? Thanks!

--------------------------------------------
Qiuping Yi
Institute Of Software
Chinese Academy of Sciences

On Tue, Jan 19, 2016 at 8:23 PM, Nema, Ashutosh <Ashutosh.Nema at
amd.com<mailto:Ashutosh.Nema at amd.com>> wrote:
You will see NULL for indirect callSite.
May need to add additional checks for this possibility.

Regards,
Ashutosh

From: llvm-dev [mailto:llvm-dev-bounces at
lists.llvm.org<mailto:llvm-dev-bounces at lists.llvm.org>] On Behalf Of
Qiuping Yi via llvm-dev
Sent: Tuesday, January 19, 2016 5:35 PM
To: llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>
Subject: [llvm-dev] Why getFunction() of CallGraphNode return NULL function?

Hi all,

I want to find all the called functions in each function, thus I iterate the
calledFunctions of each CallGraphNode in CallGraph as follow:

for (CallGraph::iterator it = CG->begin(); it != CG->end(); ++it) {
   CallGraphNode* node = it->second;
   for (CallGraphNode::iterator it2 = node->begin(); it2 != node->end();
++it2) {
      Function* calledFunc = it2->second=>getFunction();
      cerr <<　”function: “ << calledFunc->getName().str()
<<"\n";  // crash some times
      ... ...
      ... ...
    }
}

I found that some time "calledFunc" is NULL function and thus the
output crash. I don't known why? If the before code is wrong, so what is the
correct method for get all the called functions?

I use LLVM 3.6. Thank you all in advance.

--------------------------------------------
Qiuping Yi
Institute Of Software
Chinese Academy of Sciences

-------------- next part --------------
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Qiuping Yi via llvm-dev

2016-Jan-20 06:42 UTC

head link

[llvm-dev] Why getFunction() of CallGraphNode return NULL function?

OK, I know, thank you very much.


--------------------------------------------
Qiuping Yi
Institute Of Software
Chinese Academy of Sciences

On Wed, Jan 20, 2016 at 2:38 PM, Nema, Ashutosh <Ashutosh.Nema at amd.com>
wrote:
> For indirect callSite it’s hard to know the target(or actual) function
> statically because there can be multiple possibilities.
>
>
>
> Regards,
>
> Ashutosh
>
>
>
> *From:* Qiuping Yi [mailto:yiqiuping at gmail.com]
> *Sent:* Wednesday, January 20, 2016 12:03 PM
>
> *To:* Nema, Ashutosh
> *Cc:* llvm-dev
> *Subject:* Re: [llvm-dev] Why getFunction() of CallGraphNode return NULL
> function?
>
>
>
>
>
> So, I won't know the called function statically, Right?
>
>
>
> --------------------------------------------
> Qiuping Yi
> Institute Of Software
> Chinese Academy of Sciences
>
>
>
> On Wed, Jan 20, 2016 at 2:24 PM, Nema, Ashutosh <Ashutosh.Nema at
amd.com>
> wrote:
>
> Typically for C++ virtual function you will see an indirect callSite
> (unless not de-virtualized).
>
>
>
> Regards,
>
> Ashutosh
>
>
>
> *From:* Qiuping Yi [mailto:yiqiuping at gmail.com]
> *Sent:* Wednesday, January 20, 2016 9:10 AM
> *To:* Nema, Ashutosh
> *Cc:* llvm-dev
> *Subject:* Re: [llvm-dev] Why getFunction() of CallGraphNode return NULL
> function?
>
>
>
> Dear Ashutosh,
>
>
>
> Thank you, I can handle some indirect callSites by getFunction() of
> InvokInst and CallInst.
>
>
>
> However, when I am handling C++ programs, I found the calls of member
> functions are converted
>
> to some strange  indirect calls. For example:
>
>
>
> table->truncate(sysTransaction);   // from mysql
>
>
>
> are translated to the next complex llvm IR:
>
>
>
> _ZN8Database20getSystemTransactionEv.exit:        ; preds = %bb33
>
>   call void @llvm.dbg.value(metadata %class.Transaction.553* %tmp36, i64
> 0, metadata !7310, metadata !53545), !dbg !69981
>
>   %tmp37 = bitcast %class.Table.543* %table to void (%class.Table.543*,
> %class.Transaction.553*)***, !dbg !69982
>
>   %tmp38 = load void (%class.Table.543*, %class.Transaction.553*)***
> %tmp37, align 8, !dbg !69982, !tbaa !53550
>
>   %tmp39 = getelementptr inbounds void (%class.Table.543*,
> %class.Transaction.553*)** %tmp38, i64 5, !dbg !69982
>
>   %tmp40 = load void (%class.Table.543*, %class.Transaction.553*)**
> %tmp39, align 8, !dbg !69982
>
>   invoke void %tmp40(%class.Table.543* %table, %class.Transaction.553*
> %tmp36)
>
>           to label %bb41 unwind label %bb72, !dbg !69982
>
>
>
> and thus I cannot find the called function "truncate" from
"invoke void
> %tmp40(...)", what should I do?
>
> I didn't analysis C++ code with llvm, does all the function calls
through
> objects are translated to such complex indirect calls?
>
> If so, how can I dereference such functions? Thanks!
>
>
>
>
>
> --------------------------------------------
> Qiuping Yi
> Institute Of Software
> Chinese Academy of Sciences
>
>
>
> On Tue, Jan 19, 2016 at 8:23 PM, Nema, Ashutosh <Ashutosh.Nema at
amd.com>
> wrote:
>
> You will see NULL for indirect callSite.
>
> May need to add additional checks for this possibility.
>
>
>
> Regards,
>
> Ashutosh
>
>
>
> *From:* llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] *On Behalf Of
*Qiuping
> Yi via llvm-dev
> *Sent:* Tuesday, January 19, 2016 5:35 PM
> *To:* llvm-dev at lists.llvm.org
> *Subject:* [llvm-dev] Why getFunction() of CallGraphNode return NULL
> function?
>
>
>
> Hi all,
>
>
>
> I want to find all the called functions in each function, thus I iterate
> the calledFunctions of each CallGraphNode in CallGraph as follow:
>
>
>
> for (CallGraph::iterator it = CG->begin(); it != CG->end(); ++it) {
>
>    CallGraphNode* node = it->second;
>
>    for (CallGraphNode::iterator it2 = node->begin(); it2 !=
node->end();
> ++it2) {
>
>       Function* calledFunc = it2->second=>getFunction();
>
>       cerr << ”function: “ << calledFunc->getName().str()
<<"\n";  *//
> crash some times*
>
>       ... ...
>
>       ... ...
>
>     }
>
> }
>
>
>
> I found that some time "calledFunc" is NULL function and thus the
output
> crash. I don't known why? If the before code is wrong, so what is the
> correct method for get all the called functions?
>
>
>
> I use LLVM 3.6. Thank you all in advance.
>
>
> --------------------------------------------
> Qiuping Yi
> Institute Of Software
> Chinese Academy of Sciences
>
>
>
>
>-------------- next part --------------
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llvm dev - Jan 2016 - Why getFunction() of CallGraphNode return NULL function?

[llvm-dev] Why getFunction() of CallGraphNode return NULL function?

[llvm-dev] Why getFunction() of CallGraphNode return NULL function?

[llvm-dev] Why getFunction() of CallGraphNode return NULL function?