llvm dev - May 2019 - Crash with llvm 8.0.0 and -fembed-bitcode option

Hi,

I found a bug in llvm 8.0.0.
When you compile with the "-fembed-bitcode" option it will lead to a
crash when executing the output binary.


For unknown reason the assembled x86 code is different when the
"-fembed-bitcode" option is supplied.

It works with clang 7.0.1

a.cpp:
#include <string>
#include <iostream>

int func(int a);

int main(int argc, char **argv) {
std::string s = std::to_string(func(argc));
std::cout << s << std::endl;
return 0;
}

b.cpp:
int func(int a) {
return a+1;
}


Compile with:

=> clang++-8 a.cpp b.cpp -fembed-bitcode && ./a.out


and it fails:

=> [1]    14811 segmentation fault (core dumped)  ./a.out



Compile with:

=> clang++-8 a.cpp b.cpp  && ./a.out


and it works:

=> 2




Best Regards,

Peter


--



[Thales]

Peter Garba
Software Security Expert

Gemalto is now part of the Thales Group.
Please note that my new email address is peter.garba at
thalesgroup.com<mailto:peter.garba at thalesgroup.com>



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On 05/23/2019 08:26 AM, Garba Peter via llvm-dev wrote:
> Hi,
> 
> I found a bug in llvm 8.0.0. 
> When you compile with the "-fembed-bitcode" option it will lead
to a crash when executing the output binary.
> 
Can you file a bug for this at bugs.llvm.org and cc me?

-Tom
> For unknown reason the assembled x86 code is different when the
"-fembed-bitcode" option is supplied.
> 
> It works with clang 7.0.1
> 
> 
> a.cpp:
> #include <string>
> #include <iostream>
> 
> int func(int a);
> 
> int main(int argc, char **argv) {
> std::string s = std::to_string(func(argc));
> std::cout << s << std::endl;
> return 0;
> }
> 
> b.cpp:
> int func(int a) {
> return a+1;
> }
> 
> 
> Compile with:
> 
> => clang++-8 a.cpp b.cpp -fembed-bitcode && ./a.out
> 
> 
> and it fails:
> 
> => [1]    14811 segmentation fault (core dumped)  ./a.out
> 
> 
> 
> Compile with:
> 
> => clang++-8 a.cpp b.cpp  && ./a.out 
> 
> 
> and it works:
> 
> => 2
> 
> 
> 
> 
> Best Regards,
> 
> Peter
> 
> 
> -- 
> 
> 
> 
> Thales
> 
> *Peter Garba*
> Software Security Expert
> 
> Gemalto is now part of the Thales Group.
> Please note that my new email address is peter.garba at thalesgroup.com
<mailto:peter.garba at thalesgroup.com>
> 
>  
> 
> *THALES*
> 
> Werinherstr. 81
> 
> 81541 Munich
> 
> www.thalesgroup.com
<https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.thalesgroup.com&data=02%7C01%7Cpeter.garba%40gemalto.com%7C6f3ba1b0164240a99de008d6ceea71e0%7C37d0a9db7c464096bfe31add5b495d6d%7C0%7C0%7C636923903659973465&sdata=eldBP%2B%2Ff6Y9qDDywWLI98CGNeZwtG4dOrNYRuUuZEdw%3D&reserved=0>
> 
>
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> This message and any attachments are intended solely for the addressees and
may contain confidential information. Any unauthorized use or disclosure, either
whole or partial, is prohibited.
> E-mails are susceptible to alteration. Our company shall not be liable for
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recipient of this message, please delete it and notify the sender.
> Although all reasonable efforts have been made to keep this transmission
free from viruses, the sender will not be liable for damages caused by a
transmitted virus.
> 
> 
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