thr3ads.net - llvm dev - [LLVMdev] How to detect all free() calls [Mar 2013]

If this information is useful, please help other people find it:
Share via:

Jane

2013-Mar-11 05:56 UTC

[LLVMdev] How to detect all free() calls

Thanks. isFreeCall() works well but for
%call2 = call i32 bitcast (i32 (...)* @free to i32 (i8*)*)(i8* %call1) nounwind,
!dbg !16
So I tried to figure out when the above instruction occurred.
When <stdlib.h> is included,   free(buf2R1); turn into  call void
@free(i8* %call1) nounwind, !dbg !16
when I forget to include <stdlib.h>, free(buf2R1); turn into  %call2 =
call i32 bitcast (i32 (...)* @free to i32 (i8*)*)(i8* %call1) nounwind, !dbg !16
I don't understand why this is happen. Could you explain it for me?


------------------ Original ------------------
From:  "Xi Wang"<xi.wang at gmail.com>;
Date:  Mon, Mar 11, 2013 12:24 PM
To:  "Jane"<270611649 at qq.com>; 
Cc:  "llvmdev"<llvmdev at cs.uiuc.edu>; 
Subject:  Re: [LLVMdev] How to detect all free() calls



Try isFreeCall() defined in "llvm/Analysis/MemoryBuiltins.h".

On Mon, Mar 11, 2013 at 12:17 AM, Jane <270611649 at qq.com>
wrote:>
> Hi,
>     I'm trying to write a pass to detect all free()/delete() call
> instructions in LLVM IR.The method is as follows.
>     First I find Call Instructions: CallInst
*CI=dyn_cast<CallInst>(&*i);
>     then see if the Function name matches:
>                         name=CI->getCalledFunction()->getName();
>
if(name=="_ZdlPv"||name=="_ZdaPv"||name=="free")
>     It worked but when  something like this occurs
>     %call2 = call i32 bitcast (i32 (...)* @free to i32 (i8*)*)(i8* %call1)
> nounwind, !dbg !16
>     It seems like a indirect function call and I don't know how to
detect
> free() in such situation.
>     By the way, is there any way that is more convenient to detect all
> free()/delete() call instructions in a module except by matching the
> function name?
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20130311/74389452/attachment.html>

Xi Wang

2013-Mar-11 06:58 UTC

head link

[LLVMdev] How to detect all free() calls

if you don't include stdlib.h, where free() is declared, you'll simply
get a default C function signature:

int free(...);

On Mon, Mar 11, 2013 at 1:56 AM, Jane <270611649 at qq.com>
wrote:> Thanks. isFreeCall() works well but for
> %call2 = call i32 bitcast (i32 (...)* @free to i32 (i8*)*)(i8* %call1)
> nounwind, !dbg !16
> So I tried to figure out when the above instruction occurred.
> When <stdlib.h> is included,   free(buf2R1); turn into  call void
@free(i8*
> %call1) nounwind, !dbg !16
> when I forget to include <stdlib.h>, free(buf2R1); turn into  %call2
= call
> i32 bitcast (i32 (...)* @free to i32 (i8*)*)(i8* %call1) nounwind, !dbg !16
> I don't understand why this is happen. Could you explain it for me?
>
> ------------------ Original ------------------
> From:  "Xi Wang"<xi.wang at gmail.com>;
> Date:  Mon, Mar 11, 2013 12:24 PM
> To:  "Jane"<270611649 at qq.com>;
> Cc:  "llvmdev"<llvmdev at cs.uiuc.edu>;
> Subject:  Re: [LLVMdev] How to detect all free() calls
>
> Try isFreeCall() defined in "llvm/Analysis/MemoryBuiltins.h".
>
> On Mon, Mar 11, 2013 at 12:17 AM, Jane <270611649 at qq.com> wrote:
>>
>> Hi,
>>     I'm trying to write a pass to detect all free()/delete() call
>> instructions in LLVM IR.The method is as follows.
>>     First I find Call Instructions: CallInst
*CI=dyn_cast<CallInst>(&*i);
>>     then see if the Function name matches:
>>                         name=CI->getCalledFunction()->getName();
>>
if(name=="_ZdlPv"||name=="_ZdaPv"||name=="free")
>>     It worked but when  something like this occurs
>>     %call2 = call i32 bitcast (i32 (...)* @free to i32 (i8*)*)(i8*
%call1)
>> nounwind, !dbg !16
>>     It seems like a indirect function call and I don't know how to
detect
>> free() in such situation.
>>     By the way, is there any way that is more convenient to detect all
>> free()/delete() call instructions in a module except by matching the
>> function name?
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>

Dmitry Mikushin

2013-Mar-11 13:58 UTC

head link

[LLVMdev] How to detect all free() calls

Hi Jane,

On your bitcast case: you can easily strip them using:

Function* callee
dyn_cast<Function>(call->getCalledValue()->stripPointerCasts());

- D.

2013/3/11 Xi Wang <xi.wang at gmail.com>
> if you don't include stdlib.h, where free() is declared, you'll
simply
> get a default C function signature:
>
> int free(...);
>
> On Mon, Mar 11, 2013 at 1:56 AM, Jane <270611649 at qq.com> wrote:
> > Thanks. isFreeCall() works well but for
> > %call2 = call i32 bitcast (i32 (...)* @free to i32 (i8*)*)(i8* %call1)
> > nounwind, !dbg !16
> > So I tried to figure out when the above instruction occurred.
> > When <stdlib.h> is included,   free(buf2R1); turn into  call
void
> @free(i8*
> > %call1) nounwind, !dbg !16
> > when I forget to include <stdlib.h>, free(buf2R1); turn into 
%call2 > call
> > i32 bitcast (i32 (...)* @free to i32 (i8*)*)(i8* %call1) nounwind,
!dbg
> !16
> > I don't understand why this is happen. Could you explain it for
me?
> >
> > ------------------ Original ------------------
> > From:  "Xi Wang"<xi.wang at gmail.com>;
> > Date:  Mon, Mar 11, 2013 12:24 PM
> > To:  "Jane"<270611649 at qq.com>;
> > Cc:  "llvmdev"<llvmdev at cs.uiuc.edu>;
> > Subject:  Re: [LLVMdev] How to detect all free() calls
> >
> > Try isFreeCall() defined in
"llvm/Analysis/MemoryBuiltins.h".
> >
> > On Mon, Mar 11, 2013 at 12:17 AM, Jane <270611649 at qq.com>
wrote:
> >>
> >> Hi,
> >>     I'm trying to write a pass to detect all free()/delete()
call
> >> instructions in LLVM IR.The method is as follows.
> >>     First I find Call Instructions: CallInst
> *CI=dyn_cast<CallInst>(&*i);
> >>     then see if the Function name matches:
> >>                        
name=CI->getCalledFunction()->getName();
> >>
if(name=="_ZdlPv"||name=="_ZdaPv"||name=="free")
> >>     It worked but when  something like this occurs
> >>     %call2 = call i32 bitcast (i32 (...)* @free to i32 (i8*)*)(i8*
> %call1)
> >> nounwind, !dbg !16
> >>     It seems like a indirect function call and I don't know
how to
> detect
> >> free() in such situation.
> >>     By the way, is there any way that is more convenient to detect
all
> >> free()/delete() call instructions in a module except by matching
the
> >> function name?
> >>
> >> _______________________________________________
> >> LLVM Developers mailing list
> >> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> >> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> >>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20130311/1134a84c/attachment.html>

Possibly Parallel Threads

Search for more possibly parallel threads

llvm dev - Mar 2013 - [LLVMdev] How to detect all free() calls

[LLVMdev] How to detect all free() calls

[LLVMdev] How to detect all free() calls

[LLVMdev] How to detect all free() calls

Possibly Parallel Threads