[LLVMdev] llvm-stress for fuzzing llvm

[Joey Gouly]

Attached is a simple bash script I wrote to run llvm-stress several times,
might be useful!

Thanks
Joey

On 27 February 2012 19:14, Sean Silva <silvas at purdue.edu> wrote:

> Here is that patch.
>
> Btw, I've just been using bugpoint, and it's really nifty!
>
> --Sean Silva
>
> 2012/2/27 Rotem, Nadav <nadav.rotem at intel.com>
>
> Sean,
>>
>> Thanks for looking at this.  Knowing that the last instruction triggered
>> the bug is often not enough.  I use bugpoint to reduce the failing test.
>>  The reason is that some of the bugs may be caused by the interaction
>> between several instruction.  Having said that, I think that the change
>> that you proposed is a good one.  Can you send a patch ?
>>
>> Thanks,
>> Nadav
>>
>>
>> From: Sean Silva [mailto:silvas at purdue.edu]
>> Sent: Monday, February 27, 2012 05:45
>> To: Hal Finkel
>> Cc: Rotem, Nadav; llvmdev at cs.uiuc.edu
>> Subject: Re: [LLVMdev] llvm-stress for fuzzing llvm
>>
>> I'm finding it useful to replace the main loop with:
>>   for (unsigned i = 0, n = SizeCL/Modifiers.size(); i < n; ++i) {
>>       Modifiers[i%Modifiers.size()]->Act();
>>   }
>>
>> That way, changing the size by 1 adds exactly one instruction, which
>> makes delta debugging MUCH easier. Maybe it would be worth changing?
>>
>> --Sean Silva
>>
>> On Sun, Feb 26, 2012 at 9:23 PM, Sean Silva <silvas at purdue.edu> wrote:
>> Wow, nifty tool! I've already found a couple crashes!
>>
>> It is also really easy to pinpoint what is causing the error. Whenever
>> you trigger a bug, run llvm-stress with the same seed but a really small
>> size that doesn't trigger the bug (e.g. like 10). Then do binary search on
>> the size. Eventually you find exactly the cutoff of size that triggers the
>> bug (e.g. 539 runs fine, but 540 crashes), and then you can diff the
>> crashing and non-crashing .ll files and there should only be a tiny
>> difference.
>>
>> --Sean Silva
>>
>> On Sun, Feb 26, 2012 at 7:29 PM, Hal Finkel <hfinkel at anl.gov> wrote:
>> Nadav,
>>
>> Thanks, this is neat! Here is a patch which optionally enables
>> generation of the other floating-point types. Please review.
>>
>>  -Hal
>>
>> On Sun, 26 Feb 2012 11:51:04 +0000
>> "Rotem, Nadav" <nadav.rotem at intel.com> wrote:
>>
>> > Hi,
>> >
>> > Compiling lots of 'junk' helps in catching bugs.  I added a new tool
>> > (located under llvm/tools/llvm-stress) for generating random LL
>> > files.  The tool can be used to test different llvm components using
>> > various compilation flags.  Until now, I only found bugs in the
>> > codegen, and not in general llvm optimizations. This probably means
>> > that the generated tests are currently too simple for the
>> > higher-level optimizations.
>> >
>> > The command line below generates a random ll file, and llc compiles
>> > this file. It often crashes.
>> >
>> > ./llvm-stress -seed $RANDOM -o tmp.ll -size 1000 ; ./llc tmp.ll
>> > -mcpu=corei7-avx -mattr=+avx -o /dev/null
>> >
>> > The "-seed" flag sets the initial seed to be used by the random
>> > function.  I implemented a simple portable 'random' function so that
>> > the result should be identical on all platforms. The initial seed
>> > also appears in the name of the generated function.  The "-size"
>> > parameter sets the size of the generated random file.
>> >
>> > Nadav
>> > ---------------------------------------------------------------------
>> > Intel Israel (74) Limited
>> >
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>>
>> --
>> Hal Finkel
>> Postdoctoral Appointee
>> Leadership Computing Facility
>> Argonne National Laboratory
>>
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>>
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>>
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>
>
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