[cfe-users] Clang9 UBSan and GMP

David Blaikie via cfe-users cfe-users at lists.llvm.org
Fri Oct 25 15:14:34 PDT 2019

Yeah, coming across compiler bugs does happen - but more often it's bugs in
input programs. (one of the reasons compiler engineers aren't likely to
jump on reproducing and reducing misbehaving programs, because on the odds,
it's not a bug in the compiler)

On Fri, Oct 25, 2019 at 3:12 PM Hans Ã…berg <haberg-1 at telia.com> wrote:

> 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).
> >
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