[PPL-devel] Fwd: ppl 0.11.2 vs llvm

[Jack Howarth]

On Sun, Aug 07, 2011 at 05:41:28PM +0200, Roberto Bagnara wrote:
> On 08/07/11 17:33, Jack Howarth wrote:
>> On Sun, Aug 07, 2011 at 05:23:15PM +0200, Roberto Bagnara wrote:
>>> On 08/07/11 16:56, Jack Howarth wrote:
>>>> On Sun, Aug 07, 2011 at 09:31:46AM +0200, Roberto Bagnara wrote:
>>>>> On 08/06/11 14:14, Jack Howarth wrote:
>>>>>>       I am rather baffled that you can't reproduce this problem on Linux.
>>>>>> Attached is a build and make check log from x86_64 Fedora 10 using the
>>>>>> ppl 0.11.2 release and the binary distribution of the clang 2.9 compilers
>>>>>> fromhttp://llvm.org/releases/2.9/clang+llvm-2.9-x86_64-linux.tar.bz2.
>>>>>> With CC set to clang and CXX set to clang++, I see the same failures as
>>>>>> under the clang compilers from Xcode 4.1 under Lion.
>>>>>
>>>>> Hi Jack,
>>>>>
>>>>> please try configuring the PPL with --disable-fpmath on both platforms
>>>>> and let us know if `make check' passes this way.
>>>>
>>>>      Building ppl9 with...
>>>>
>>>>     $ ../configure --prefix=/sw --mandir=/sw/share/man --infodir=/sw/share/info --disable-static --enable-pch --with-java=/System/Library/Frameworks/JavaVM.framework/Home CFLAGS=-g -O2 -pipe -fpch-preprocess -fPIC -fwrapv CXXFLAGS=-g -O2 -pipe -fpch-preprocess -fPIC -fwrapv CPPFLAGS=-I/System/Library/Frameworks/JavaVM.framework/Headers --enable-check=thorough --disable-fpmath -C
>>>>
>>>> produces no testsuite failures when using clang3.0svn from Xcode 4.1. I'll repeat this with the stock llvm-gcc-4.2
>>>> system compilers from Xcode 4.1 as well.
>>>
>>> Great, thanks!
>>
>> Roberto,
>>    The results for llvm-gcc-4.2 from Xcode 4.1 weren't as positive. The testcase...
>>
>> /bin/sh: line 1: 91482 Segmentation fault: 11  ${dir}$tst
>> FAIL: simplifyusingcontext1
>>
>> segfaults with --disable-fpmath. I wouldn't worry too much about that as Apple is
>> using a much older llvm release for llvm-gcc-4.2 than clang3.0svn in Xcode 4.1.
>> Also, their usual response to llvm-gcc bugs is that it is being depreciated in
>> favor of clang and to use that compiler instead.

Roberto,
    I tried a build with dragonegg 3.0svn and FSF gcc 4.5.3 using --disable-fpmath. This
combination builds ppl 0.11.2 without regressions in the testsuite. So the llvm-gcc-4.2
issue in Xcode 4.1 is likely a bug in their older llvm release used there and can be
ignored since clang3.0svn in Xcode 4.1 works fine.

>
> I am pretty confident this is a compiler bug.
>
>>    Is --disable-fpmath our only option here?
>
> The only other option I see is to debug the compiler bug.

You are talking about the failures seen without --disable-fpmath, correct?
Is this really a compiler bug with clang? I thought it was due to the fact that
ppl is coded to expect a functional -frounding-math option to be present. This isn't
really a compiler bug but a compiler limitation, no?
               Jack

> I guess it will not be an easy task though.
> Cheers,
>
>    Roberto
>
> -- 
> Prof. Roberto Bagnara
> Applied Formal Methods Laboratory
> Department of Mathematics, University of Parma, Italy
> http://www.cs.unipr.it/~bagnara/
> mailto:bagnara at cs.unipr.it
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