Re: [csmith-dev] Is this a wrong code bug?

[John Regehr <regehr@cs.utah.edu>]

Yes, this is either a wrong code bug in clang or else a bug where Csmith 
emitted an insufficiently defined program, you'll need to determine 
which of these is the case.

Also I'm confused about why gcc and clang would return different results 
-- generally they make the same decisions for implementation-defined 
behaviors. This is worth investigating as well.

John


On 1/25/19 3:56 AM, sameeran joshi wrote:
> Hi,
> compiling a program as
> gcc -O0  --------> CHECKSUM : 72D53249
> gcc -O1  --------> CHECKSUM : 72D53249
> gcc -O2 --------> CHECKSUM : 72D53249
> gcc -O3  --------> CHECKSUM : 72D53249
> gcc -Os  --------> CHECKSUM : 72D53249
> gcc -Ofast  --------> CHECKSUM : 72D53249
>
> **clang -O0  --------> CHECKSUM : 2873C061**(differs)
>
> clang -O1  --------> CHECKSUM : 10301700
> clang -O2  --------> CHECKSUM : 10301700
> clang -O3  --------> CHECKSUM : 10301700
> clang -Os  --------> CHECKSUM : 10301700
> clang -Ofast  --------> CHECKSUM : 10301700
>
> is this a wrong code bug found using differential testing approach?
> Thanks,
> Sameeran Joshi