[llvm] r217144 - Enable noalias metadata by default and swap the order of the SLP and Loop vectorizers by default.

[Yi Kong]

Yes, by placing an extra EarlyCSE invocation immediately after
LoopVectorizer, I can reproduce the issue.

Cheers,
Yi

On 26 September 2014 17:24, Hal Finkel <hfinkel at anl.gov> wrote:
> ----- Original Message -----
>> From: "Yi Kong" <kongy.dev at gmail.com>
>> To: "Hal Finkel" <hfinkel at anl.gov>
>> Cc: llvm-commits at cs.uiuc.edu, "James Molloy" <james.molloy at arm.com>
>> Sent: Friday, September 26, 2014 9:41:54 AM
>> Subject: Re: [llvm] r217144 - Enable noalias metadata by default and swap the order of the SLP and Loop vectorizers
>> by default.
>>
>> Hi Hal,
>>
>> Loop vectorizer is found to cause the regression. The LLVM IR
>> immediately after the loop vectorizer may be malformed, which is
>> unveiled by EarlyCSE pass enabled by '-fslp-vectorize-aggressive'.
>
> Okay, but BBVectorize runs before the EarlyCSE invocation. Are you sure that it is the loop vectorizer that is doing it?
>
> Thanks again,
> Hal
>
>>
>> I've filed a bug report against it.
>>
>> Thanks,
>> Yi
>>
>> On 26 September 2014 01:10, Hal Finkel <hfinkel at anl.gov> wrote:
>> > Hi Yi,
>> >
>> > This is almost likely a bug in BBVectorize. Can you please file a
>> > bug report.
>> >
>> > Out of curiosity, are there still cases where
>> > -fslp-vectorize-aggressive provides additional speedup over -O3
>> > (which should now include -fslp-vectorize)?
>> >
>> > Thanks again,
>> > Hal
>> >
>> > ----- Original Message -----
>> >> From: "Yi Kong" <kongy.dev at gmail.com>
>> >> To: "James Molloy" <james.molloy at arm.com>
>> >> Cc: llvm-commits at cs.uiuc.edu
>> >> Sent: Thursday, September 25, 2014 6:58:24 PM
>> >> Subject: Re: [llvm] r217144 - Enable noalias metadata by default
>> >> and swap the order of the SLP and Loop vectorizers
>> >> by default.
>> >>
>> >> Hi James,
>> >>
>> >> This patch is causing a bunch of failures in LNT test suite, when
>> >> compiling with `-O3 -fslp-vectorize-aggressive`. Clang fails when
>> >> trying to do the CSE after BBVectorize.
>> >>
>> >> -Yi
>> >>
>> >> New Failures - Compile Time
>> >> MultiSource/Applications/ClamAV/clamscan
>> >> MultiSource/Applications/JM/ldecod/ldecod
>> >> MultiSource/Applications/JM/lencod/lencod
>> >> MultiSource/Applications/oggenc/oggenc
>> >> MultiSource/Benchmarks/7zip/7zip-benchmark
>> >> MultiSource/Benchmarks/FreeBench/neural/neural
>> >> MultiSource/Benchmarks/MallocBench/espresso/espresso
>> >> MultiSource/Benchmarks/MiBench/consumer-lame/consumer-lame
>> >> SingleSource/Benchmarks/CoyoteBench/lpbench
>> >>
>> >> Error message:
>> >> $ clang lpbench.c --target=aarch64-linux-gnu -O3
>> >> -fslp-vectorize-aggressive
>> >> Instruction does not dominate all uses!
>> >>   %cmp.zero241 = icmp eq i64 %n.vec239, 0
>> >>   br i1 %cmp.zero241, label %middle.block, label %vector.memcheck
>> >> Instruction does not dominate all uses!
>> >>   %n.vec239 = and i64 %0, -4
>> >>   %37 = icmp eq i64 %index.next, %n.vec239
>> >> Instruction does not dominate all uses!
>> >>   %n.vec239 = and i64 %0, -4
>> >>   %resume.val = phi i64 [ 0, %overflow.checked ], [ 0,
>> >> %vector.memcheck ], [ %n.vec239, %vector.body ]
>> >> Instruction does not dominate all uses!
>> >>   %cmp.zero241 = icmp eq i64 %n.vec239, 0
>> >>   br i1 %cmp.zero241, label %middle.block184, label
>> >>   %vector.memcheck205
>> >> Instruction does not dominate all uses!
>> >>   %n.vec239 = and i64 %0, -4
>> >>   %56 = icmp eq i64 %index.next211, %n.vec239
>> >> Instruction does not dominate all uses!
>> >>   %n.vec239 = and i64 %0, -4
>> >>   %resume.val206 = phi i64 [ 0, %overflow.checked192 ], [ 0,
>> >> %vector.memcheck205 ], [ %n.vec239, %vector.body183 ]
>> >> fatal error: error in backend: Broken function found, compilation
>> >> aborted!
>> >> clang: error: clang frontend command failed with exit code 70 (use
>> >> -v
>> >> to see invocation)
>> >> clang version 3.6.0 (trunk 217400)
>> >> Target: aarch64--linux-gnu
>> >> Thread model: posix
>> >> clang: note: diagnostic msg: PLEASE submit a bug report to
>> >> http://llvm.org/bugs/ and include the crash backtrace,
>> >> preprocessed
>> >> source, and associated run script.
>> >> clang: note: diagnostic msg:
>> >> ********************
>> >>
>> >> PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
>> >> Preprocessed source(s) and associated run script(s) are located
>> >> at:
>> >> clang: note: diagnostic msg: /tmp/lpbench-8701bf.c
>> >> clang: note: diagnostic msg: /tmp/lpbench-8701bf.sh
>> >> clang: note: diagnostic msg:
>> >>
>> >> ********************
>> >>
>> >> On 4 September 2014 14:23, James Molloy <james.molloy at arm.com>
>> >> wrote:
>> >> > Author: jamesm
>> >> > Date: Thu Sep  4 08:23:08 2014
>> >> > New Revision: 217144
>> >> >
>> >> > URL: http://llvm.org/viewvc/llvm-project?rev=217144&view=rev
>> >> > Log:
>> >> > Enable noalias metadata by default and swap the order of the SLP
>> >> > and Loop vectorizers by default.
>> >> >
>> >> > After some time maturing, hopefully the flags themselves will be
>> >> > removed.
>> >> >
>> >> > Modified:
>> >> >     llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
>> >> >     llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp
>> >> >
>> >> > Modified: llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
>> >> > URL:
>> >> > http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp?rev=217144&r1=217143&r2=217144&view=diff
>> >> > ==============================================================================
>> >> > --- llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
>> >> > (original)
>> >> > +++ llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp Thu Sep
>> >> >  4
>> >> > 08:23:08 2014
>> >> > @@ -62,7 +62,7 @@ static cl::opt<bool> RunLoadCombine("com
>> >> >
>> >> >  static cl::opt<bool>
>> >> >  RunSLPAfterLoopVectorization("run-slp-after-loop-vectorization",
>> >> > -  cl::init(false), cl::Hidden,
>> >> > +  cl::init(true), cl::Hidden,
>> >> >    cl::desc("Run the SLP vectorizer (and BB vectorizer) after
>> >> >    the
>> >> >    Loop "
>> >> >             "vectorizer instead of before"));
>> >> >
>> >> >
>> >> > Modified: llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp
>> >> > URL:
>> >> > http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp?rev=217144&r1=217143&r2=217144&view=diff
>> >> > ==============================================================================
>> >> > --- llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp
>> >> > (original)
>> >> > +++ llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp Thu Sep
>> >> >  4
>> >> > 08:23:08 2014
>> >> > @@ -42,7 +42,7 @@
>> >> >  using namespace llvm;
>> >> >
>> >> >  static cl::opt<bool>
>> >> > -EnableNoAliasConversion("enable-noalias-to-md-conversion",
>> >> > cl::init(false),
>> >> > +EnableNoAliasConversion("enable-noalias-to-md-conversion",
>> >> > cl::init(true),
>> >> >    cl::Hidden,
>> >> >    cl::desc("Convert noalias attributes to metadata during
>> >> >    inlining."));
>> >> >
>> >> >
>> >> >
>> >> > _______________________________________________
>> >> > llvm-commits mailing list
>> >> > llvm-commits at cs.uiuc.edu
>> >> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>> >> _______________________________________________
>> >> llvm-commits mailing list
>> >> llvm-commits at cs.uiuc.edu
>> >> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>> >>
>> >
>> > --
>> > Hal Finkel
>> > Assistant Computational Scientist
>> > Leadership Computing Facility
>> > Argonne National Laboratory
>>
>
> --
> Hal Finkel
> Assistant Computational Scientist
> Leadership Computing Facility
> Argonne National Laboratory