[cfe-users] Clang9 UBSan and GMP

[Hans Åberg via cfe-users]

The sources are available at [1]; it is written in C, not C++. I was was hoping that that something like UBSan would shed light on it, but the original question is answered: it changes optimization. The GMP developers say that they have caught some compiler bugs, but that is hard to do and time consuming.

1. https://gmplib.org


> On 25 Oct 2019, at 23:38, David Blaikie <dblaikie at gmail.com> wrote:
> 
> It's hard to know if it's the compiler's fault without a test case - due to the nature of undefined behavior and other things (implementation defined behavior and unspecified behavior) in C++, that the program behaves as expected with another compiler or another set of flags doesn't give a strong indication as to where the problem is (in the code, in one of the compilers, etc).
>