llvm dev - Dec 2010 - [LLVMdev] Bad gcc versions

I have been tracking down various build problems and found some
more gcc versions that don't work.  4.4.x and 4.5.x seem to
be particularly bad.

In addition to the set of bad gcc versions posted on the web,
can we create a list of known-good gcc versions?  It took me
a long time to figure out a good combination.

On SLES 10.1 x86_64, gcc 4.1.2 works reasonably well, though one
clang test fails.

Builds with gcc 4.4.4, 4.4.3, 4.4.2 and 4.5.1 all failed significant
numbers of regression tests.

                               -Dave

I think the problem is also platform dependent,  and I have been trying 
to come up with the known-good list of build gcc/g++ on various 
platforms for a long time.

E.g.,
on Debian-32 5.0.5 (Intel): gcc-4.0.4, gcc-4.1.2 are bad, gcc-4.2.4 
seems to be fine.
on Debian-64 5.0.4 (Intel): the default gcc (4.3.2) seems to be fine.

We may want to cover this for a wide range of possible platforms. The 
ones listed in the Getting Started Guide is in complete.

Chuck

On 12/8/2010 11:43 AM, David Greene wrote:
> I have been tracking down various build problems and found some
> more gcc versions that don't work.  4.4.x and 4.5.x seem to
> be particularly bad.
>
> In addition to the set of bad gcc versions posted on the web,
> can we create a list of known-good gcc versions?  It took me
> a long time to figure out a good combination.
>
> On SLES 10.1 x86_64, gcc 4.1.2 works reasonably well, though one
> clang test fails.
>
> Builds with gcc 4.4.4, 4.4.3, 4.4.2 and 4.5.1 all failed significant
> numbers of regression tests.
>
>                                 -Dave
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

On Wed, 08 Dec 2010 10:43:48 -0600
David Greene <dag at cray.com> wrote:
> I have been tracking down various build problems and found some
> more gcc versions that don't work.  4.4.x and 4.5.x seem to
> be particularly bad.
What are we left with then? Only 4.2 and 4.3?
I only use 4.4 since a while, and it works fairly well.

Are you sure it is not a bug in the regression tests themselves
(strict-aliasing bugs, etc.)?
Which regression tests are failing with LLVM 2.8 and GCC 4.4.x?
> 
> In addition to the set of bad gcc versions posted on the web,
> can we create a list of known-good gcc versions?  It took me
> a long time to figure out a good combination.
> 
> On SLES 10.1 x86_64, gcc 4.1.2 works reasonably well, though one
> clang test fails.
In ClamAV we enable LLVM only if GCC is >= 4.1.2 [*], and that has
worked fairly well.

We only had problems with Python (<2.4 are problematic),custom built Pythons
lacking thread support, some Python versions (2.5+)
just crash, etc. We also had problems with some tests (they got fixed
AFAICT) that didn't work when some backend was not built (like
X86-specific tests enabled on PPC). 

So in the latest version we don't run LLVM's make check at all, but
aside from Python bugs I didn't see any compiler bugs causing them to
fail.

[*] Certain old versions of 4.1.2 on RHEL were buggy, but recently updated
4.1.2 on RHEL worked.

Best regards,
--Edwin

Hi David,
> I have been tracking down various build problems and found some
> more gcc versions that don't work.  4.4.x and 4.5.x seem to
> be particularly bad.
I've been using 4.4 and 4.5 from ubuntu for some time and they work
fine for me.

Ciao, Duncan.
>
> In addition to the set of bad gcc versions posted on the web,
> can we create a list of known-good gcc versions?  It took me
> a long time to figure out a good combination.
>
> On SLES 10.1 x86_64, gcc 4.1.2 works reasonably well, though one
> clang test fails.
>
> Builds with gcc 4.4.4, 4.4.3, 4.4.2 and 4.5.1 all failed significant
> numbers of regression tests.
>
>                                 -Dave
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

Chuck Zhao <czhao at eecg.toronto.edu> writes:
> I think the problem is also platform dependent
Absolutely.  I find that different versions work on different platforms.
It seems odd, but that's what I see.  gcc has changed ABI a few times
so some combination of gcc and library version may not work.  But it
looks like more than just that.
> We may want to cover this for a wide range of possible platforms. The 
> ones listed in the Getting Started Guide is in complete.
Yep, that was my thought as well.  A table of gcc x platform might work.

                            -Dave

Török Edwin <edwintorok at gmail.com> writes:
> What are we left with then? Only 4.2 and 4.3?
On SLES 10.1 at least.  I think it is highly platform dependent.
> I only use 4.4 since a while, and it works fairly well.
On what platform?
> Are you sure it is not a bug in the regression tests themselves
> (strict-aliasing bugs, etc.)?
No, I'm not sure.
> Which regression tests are failing with LLVM 2.8 and GCC 4.4.x?
Too many to list.
> So in the latest version we don't run LLVM's make check at all
That's dangerous in my experience.

                               -Dave