[Please cc me, as I am not on the list.]
When compiling GMP 6.1.2 with MacPorts clang9 on MacOS 10.15, the check gives
one error, but if turning on UBSan ‘undefined’, it passes without a report.
Should it not report what it thinks is the issue?
___
c
You mentioned "the check gives one error" - which check?
On Fri, Oct 25, 2019 at 8:21 AM Hans Åberg via cfe-users <
cfe-users@lists.llvm.org> wrote:
> [Please cc me, as I am not on the list.]
>
> When compiling GMP 6.1.2 with MacPorts clang9 on MacOS 10.15, the check
> gives one error, but if tur
UBSan adds code to check things, it necessarily changes optimizations by
having those checks in. It shouldn't affect the behavior of programs that
don't exhibit UB (but I imagine it could affect the behavior of programs
relying on specific IB (Implementation Defined Behavior)).
Reducing a test ca
Hard to know what might be happening - what sort of failure you're seeing,
etc. Perhaps UBSan is stabilizing/changing unspecified rather than
undefined behavior - or the test is failing due to some undefined behavior
that UBSan doesn't catch, etc.
On Fri, Oct 25, 2019 at 11:25 AM Hans Åberg 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 i
It's pretty hard to conclude whether it's a bug in your code or in the
compiler, or both, without narrowing down a test case.
On Fri, Oct 25, 2019 at 2:01 PM Hans Åberg wrote:
> So then there probably is an issue with the optimization.
>
> Just run 'gmp-6.1.2’ with MacPorts clang 9.0.0; I got:
>
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 Åberg
UBSan doesn't catch everything - you could also try ASan and/or valgrind,
etc. (MSan if you want, but that's a bit fussier/more work to use)
On Fri, Oct 25, 2019 at 3:16 PM Hans Åberg wrote:
> That is the reason I tried the UBSan, but as it changes optimization, it
> does not wrok.
>
>
> > On 26
Hans, it’s challenging to give sensible advice/guesses without knowing which
test is failing. Maybe I missed this information in the replies (please CC the
list if you want follow up answers from more than just David). I am not a GMP
developer, but note that GMP is regularly tested with ubsan an
It is not my code, it belongs to gmp-6.1.2, I merely happened to come a cross
it. It passes on gcc9, so there is something that clang9 does.
> On 25 Oct 2019, at 23:15, David Blaikie wrote:
>
> It's pretty hard to conclude whether it's a bug in your code or in the
> compiler, or both, without
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
The ‘make check’ of GMP 6.1.2. One of the tests fail, but with any UBSan
‘undefined’ option enabled (in ‘configure’), none.
> On 25 Oct 2019, at 18:35, David Blaikie wrote:
>
> You mentioned "the check gives one error" - which check?
___
cfe-users ma
So then there probably is an issue with the optimization.
Just run 'gmp-6.1.2’ with MacPorts clang 9.0.0; I got:
../../../gmp-6.1.2/test-driver: line 107: 70037 Abort trap: 6 "$@" >
$log_file 2>&1
FAIL: t-sqrlo
With Apple clang 11.0.0 (clang-1100.0.33.8), I got another ‘make check’ err
That is the reason I tried the UBSan, but as it changes optimization, it does
not wrok.
> On 26 Oct 2019, at 00:14, David Blaikie wrote:
>
> 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 ju
It is just an abort trap. The ‘make check' also passes if turning off
optimization. I would have expected UBSan to not change anything in
optimization, but merely report the issues it finds. Apparently it finds
nothing, so it may suggest a compiler bug.
> On 25 Oct 2019, at 22:34, David Blaiki
On Fri, Oct 25, 2019 at 5:55 PM Matthew Fernandez <
matthew.fernan...@gmail.com> wrote:
> Hans, it’s challenging to give sensible advice/guesses without knowing
> which test is failing. Maybe I missed this information in the replies
> (please CC the list if you want follow up answers from more tha
The GMP developers felt it was a compiler bug, so I think I will leave it at
that. But thanks for the tips.
> On 26 Oct 2019, at 00:32, David Blaikie wrote:
>
> UBSan doesn't catch everything - you could also try ASan and/or valgrind,
> etc. (MSan if you want, but that's a bit fussier/more wo
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