llvm dev - Sep 2011 - [LLVMdev] question on difference of bitcode between C and C++

Could anybody provide me some links or pages or infos of the difference of
bitcodes of C and C++? We have implemented an optimization pass on bitcode
generated from C, and we are trying to find out whether it will work on
bitcode from C++. Thanks!

--
Best Regards,
Fei Jia
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On Sep 21, 2011, at 6:13 PM, Fei Jia wrote:
> Could anybody provide me some links or pages or infos of the difference of
bitcodes of C and C++? We have implemented an optimization pass on bitcode
generated from C, and we are trying to find out whether it will work on bitcode
from C++. Thanks!
> 
Hi Fei,

There isn't a difference in the bitcode format of a C as opposed to a C++
program. There are differences in how functions are linked, but that's a
function of the language and not the bitcode. E.g., if you want to call a C
function from C++, you need to do this:

extern "C" {
  void foo();
}

void bar() {
  foo();
}

-bw

Hi Bill,

Thanks for reply! I am sorry I didn't express my question clearly.

Examples may explain well. Now I am trying to analyze the data flow of
programs. I first compile the C code to bitcode, and then apply our
algorithm to the bitcode to find the dependency between statements. But as
to C++ code, there are class, vector, reference, I may need to revise my
algorithm to analyze bitcode from C++.

I am trying to find such difference of bitcode between C and C++.

--
Best Regards,
Fei Jia




On Wed, Sep 21, 2011 at 6:26 PM, Bill Wendling <wendling at apple.com>
wrote:
> On Sep 21, 2011, at 6:13 PM, Fei Jia wrote:
>
> > Could anybody provide me some links or pages or infos of the
difference
> of bitcodes of C and C++? We have implemented an optimization pass on
> bitcode generated from C, and we are trying to find out whether it will
work
> on bitcode from C++. Thanks!
> >
> Hi Fei,
>
> There isn't a difference in the bitcode format of a C as opposed to a
C++
> program. There are differences in how functions are linked, but that's
a
> function of the language and not the bitcode. E.g., if you want to call a C
> function from C++, you need to do this:
>
> extern "C" {
>  void foo();
> }
>
> void bar() {
>  foo();
> }
>
> -bw
>
>
>
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