[LLVMdev] How to detect all free() calls

[Jane]

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?
>
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