[llvm] r360171 - [DAGCombiner] Avoid creating large tokenfactors in visitTokenFactor
Jordan Rupprecht via llvm-commits
llvm-commits at lists.llvm.org
Tue May 21 16:12:39 PDT 2019
Hi Florian,
Sorry for the delay with this second reproducer. c-reduce was turtle slow
and didn't take it very far, and bugpoint didn't like it either and needed
some manual reducing. The .ll reproducer I have is still >5k lines :(
Repro instructions (when synced prior to reverting this commit; repro.ll is
attached):
$ time ~/dev/llc repro.ll -o /tmp/repro.o
llc:
/usr/local/google/home/rupprecht/src/llvm-project/llvm/lib/CodeGen/LiveVariables.cpp:132:
void llvm::LiveVariables::HandleVirtRegUse(unsigned int,
llvm::MachineBasicBlock *, llvm::MachineInstr &): Assertion
`MRI->getVRegDef(reg) && "Register use before def!"' failed.
Stack dump:
0. Program arguments: /usr/local/google/home/rupprecht/dev/llc
repro.ll -o /tmp/repro.o
1. Running pass 'Function Pass Manager' on module 'repro.ll'.
2. Running pass 'Live Variable Analysis' on function '@repro'
#0 0x00007f5915e1136f llvm::sys::PrintStackTrace(llvm::raw_ostream&)
/usr/local/google/home/rupprecht/src/llvm-project/llvm/lib/Support/Unix/Signals.inc:494:13
#1 0x00007f5915e0f5d0 llvm::sys::RunSignalHandlers()
/usr/local/google/home/rupprecht/src/llvm-project/llvm/lib/Support/Signals.cpp:69:18
#2 0x00007f5915e11778 SignalHandler(int)
/usr/local/google/home/rupprecht/src/llvm-project/llvm/lib/Support/Unix/Signals.inc:357:1
#3 0x00007f59156cc0c0 __restore_rt
(/lib/x86_64-linux-gnu/libpthread.so.0+0x110c0)
#4 0x00007f5914aadfcf raise (/lib/x86_64-linux-gnu/libc.so.6+0x32fcf)
#5 0x00007f5914aaf3fa abort (/lib/x86_64-linux-gnu/libc.so.6+0x343fa)
#6 0x00007f5914aa6e37 (/lib/x86_64-linux-gnu/libc.so.6+0x2be37)
#7 0x00007f5914aa6ee2 (/lib/x86_64-linux-gnu/libc.so.6+0x2bee2)
#8 0x00007f5916de41ad
(/usr/local/google/home/rupprecht/src/llvm-build/dev/bin/../lib/libLLVMCodeGen.so.9svn+0x34e1ad)
#9 0x00007f5916de641e llvm::LiveVariables::runOnInstr(llvm::MachineInstr&,
llvm::SmallVectorImpl<unsigned int>&)
/usr/local/google/home/rupprecht/src/llvm-project/llvm/lib/CodeGen/LiveVariables.cpp:542:46
#10 0x00007f5916de6b0c
llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::MachineInstr,
true, true, void>, false, false>::isEnd() const
/usr/local/google/home/rupprecht/src/llvm-project/llvm/include/llvm/ADT/ilist_iterator.h:176:31
#11 0x00007f5916de6b0c
llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::MachineInstr,
true, true, void>, false, false>
llvm::MachineInstrBundleIteratorHelper<false>::getBundleFinal<llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::MachineInstr,
true, true, void>, false, false>
>(llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::MachineInstr,
true, true, void>, false, false>)
/usr/local/google/home/rupprecht/src/llvm-project/llvm/include/llvm/CodeGen/MachineInstrBundleIterator.h:62:0
#12 0x00007f5916de6b0c void
llvm::MachineInstrBundleIteratorHelper<false>::increment<llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::MachineInstr,
true, true, void>, false, false>
>(llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::MachineInstr,
true, true, void>, false, false>&)
/usr/local/google/home/rupprecht/src/llvm-project/llvm/include/llvm/CodeGen/MachineInstrBundleIterator.h:70:0
#13 0x00007f5916de6b0c llvm::MachineInstrBundleIterator<llvm::MachineInstr,
false>::operator++()
/usr/local/google/home/rupprecht/src/llvm-project/llvm/include/llvm/CodeGen/MachineInstrBundleIterator.h:260:0
#14 0x00007f5916de6b0c
llvm::LiveVariables::runOnBlock(llvm::MachineBasicBlock*, unsigned int)
/usr/local/google/home/rupprecht/src/llvm-project/llvm/lib/CodeGen/LiveVariables.cpp:577:0
#15 0x00007f5916de7201
llvm::LiveVariables::runOnMachineFunction(llvm::MachineFunction&)
/usr/local/google/home/rupprecht/src/llvm-project/llvm/lib/CodeGen/LiveVariables.cpp:650:32
#16 0x00007f5916e4abea
llvm::MachineFunctionPass::runOnFunction(llvm::Function&)
/usr/local/google/home/rupprecht/src/llvm-project/llvm/lib/CodeGen/MachineFunctionPass.cpp:73:13
#17 0x00007f59169fcc43 llvm::FPPassManager::runOnFunction(llvm::Function&)
/usr/local/google/home/rupprecht/src/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1648:27
#18 0x00007f59169fcf53 llvm::FPPassManager::runOnModule(llvm::Module&)
/usr/local/google/home/rupprecht/src/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1685:13
#19 0x00007f59169fd3e8 (anonymous
namespace)::MPPassManager::runOnModule(llvm::Module&)
/usr/local/google/home/rupprecht/src/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1752:27
#20 0x00007f59169fd3e8 llvm::legacy::PassManagerImpl::run(llvm::Module&)
/usr/local/google/home/rupprecht/src/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1865:0
#21 0x000000000021585c compileModule(char**, llvm::LLVMContext&)
/usr/local/google/home/rupprecht/src/llvm-project/llvm/tools/llc/llc.cpp:609:8
#22 0x00000000002132dd main
/usr/local/google/home/rupprecht/src/llvm-project/llvm/tools/llc/llc.cpp:363:13
On Fri, May 10, 2019 at 11:09 PM Jordan Rupprecht <rupprecht at google.com>
wrote:
> Attached a repro.cc from creduce. Repro is just:
> $ cat repro.cc
> struct b {
> char aa;
> };
> struct __attribute__((__packed__)) d {
> char : 84211;
> char ak : 1;
> int al : 32;
> int am : 32;
> char an : 5;
> char : 5;
> char ap : 5;
> short c : 6;
> int aa : 27;
> int at : 32;
> int a;
> void e();
> };
> class f {
> void g(const b &);
> long az[];
> };
> void f::g(const b &h) {
> d a;
> a.ak = a.al = a.am = a.an = a.ap = a.c = a.aa = h.aa;
> a.at = az[0];
> a.e();
> }
> $ clang++ -O2 -fsanitize=address -o repro.o -c repro.cc
> And I just noticed that clang w/ debug prints this before the stack:
>
> clang-9: $SRC/llvm/lib/CodeGen/MachineTraceMetrics.cpp:639: (anonymous
> namespace)::DataDep::DataDep(const llvm::MachineRegisterInfo *, unsigned
> int, unsigned int): Assertion `!DefI.atEnd() && "Register has no defs"'
> failed.
>
> creduce is going a little more slowly on the code that crashed in "Live
> Variable Analysis", but I'll leave that going over the weekend. Hope this
> initial test case helps a bit.
>
> *From: *Florian Hahn <flo at fhahn.com>
> *Date: *Fri, May 10, 2019 at 4:26 PM
> *To: *Jordan Rupprecht
> *Cc: *llvm-commits
>
>
>>
>> On 11 May 2019, at 00:22, Jordan Rupprecht <rupprecht at google.com> wrote:
>>
>> Reverted in r360481. I have creduce going on the Machine InstCombiner
>> crash and down to "only" 7000 lines, so I think it will finish before I
>> leave today.
>>
>> There were some crashes in other places (i.e. I don't think the bug is in
>> this patch, it's just revealing bugs in other places), so I'll have to see
>> if those reduce to the same thing -- I'll check that out next week.
>>
>> Sorry for the inconvenience!
>>
>>
>> No worries, thanks for letting me know. I’m curious what the problem with
>> the machine combiner is.
>>
>> Cheers
>>
>> *From: *Jordan Rupprecht <rupprecht at google.com>
>> *Date: *Fri, May 10, 2019 at 3:28 PM
>> *To: *Florian Hahn
>> *Cc: *llvm-commits
>>
>> Here's the full crash (minus the boiler plate) for the one in Machine
>>> InstCombiner:
>>> #9 0x00007fb8d52cf5d2 (anonymous
>>> namespace)::DataDep::DataDep(llvm::MachineRegisterInfo const*, unsigned
>>> int, unsigned int)
>>> ${LLVM_SRC}/llvm/lib/CodeGen/MachineTraceMetrics.cpp:640:13
>>> #10 0x00007fb8d52cb644 getDataDeps(llvm::MachineInstr const&,
>>> llvm::SmallVectorImpl<(anonymous namespace)::DataDep>&,
>>> llvm::MachineRegisterInfo const*)
>>> ${LLVM_SRC}/llvm/lib/CodeGen/MachineTraceMetrics.cpp:672:22
>>> #11 0x00007fb8d52cb064
>>> llvm::MachineTraceMetrics::Ensemble::updateDepth(llvm::MachineTraceMetrics::TraceBlockInfo&,
>>> llvm::MachineInstr const&, llvm::SparseSet<llvm::LiveRegUnit,
>>> llvm::identity<unsigned int>, unsigned char>&)
>>> ${LLVM_SRC}/llvm/lib/CodeGen/MachineTraceMetrics.cpp:788:12
>>> #12 0x00007fb8d52cc300
>>> llvm::MachineTraceMetrics::Ensemble::computeInstrDepths(llvm::MachineBasicBlock
>>> const*) ${LLVM_SRC}/llvm/lib/CodeGen/MachineTraceMetrics.cpp:883:28
>>> #13 0x00007fb8d52cde9e
>>> llvm::MachineTraceMetrics::Ensemble::getTrace(llvm::MachineBasicBlock
>>> const*) ${LLVM_SRC}/llvm/lib/CodeGen/MachineTraceMetrics.cpp:1166:8
>>> #14 0x00007fb8d515ead4 (anonymous
>>> namespace)::MachineCombiner::combineInstructions(llvm::MachineBasicBlock*)
>>> ${LLVM_SRC}/llvm/lib/CodeGen/MachineCombiner.cpp:596:59
>>> #15 0x00007fb8d515e342 (anonymous
>>> namespace)::MachineCombiner::runOnMachineFunction(llvm::MachineFunction&)
>>> ${LLVM_SRC}/llvm/lib/CodeGen/MachineCombiner.cpp:654:16
>>> #16 0x00007fb8d51bf637
>>> llvm::MachineFunctionPass::runOnFunction(llvm::Function&)
>>> ${LLVM_SRC}/llvm/lib/CodeGen/MachineFunctionPass.cpp:73:8
>>> #17 0x00007fb8d47dd759
>>> llvm::FPPassManager::runOnFunction(llvm::Function&)
>>> ${LLVM_SRC}/llvm/lib/IR/LegacyPassManager.cpp:1648:23
>>> #18 0x00007fb8d47ddb9f llvm::FPPassManager::runOnModule(llvm::Module&)
>>> ${LLVM_SRC}/llvm/lib/IR/LegacyPassManager.cpp:1685:16
>>> #19 0x00007fb8d47de305 (anonymous
>>> namespace)::MPPassManager::runOnModule(llvm::Module&)
>>> ${LLVM_SRC}/llvm/lib/IR/LegacyPassManager.cpp:1752:23
>>> #20 0x00007fb8d47dde45 llvm::legacy::PassManagerImpl::run(llvm::Module&)
>>> ${LLVM_SRC}/llvm/lib/IR/LegacyPassManager.cpp:1865:16
>>> #21 0x00007fb8d47de881 llvm::legacy::PassManager::run(llvm::Module&)
>>> ${LLVM_SRC}/llvm/lib/IR/LegacyPassManager.cpp:1896:3
>>> #22 0x00007fb8d117e15a (anonymous
>>> namespace)::EmitAssemblyHelper::EmitAssembly(clang::BackendAction,
>>> std::unique_ptr<llvm::raw_pwrite_stream,
>>> std::default_delete<llvm::raw_pwrite_stream> >)
>>> ${LLVM_SRC}/clang/lib/CodeGen/BackendUtil.cpp:894:3
>>>
>>>
>>> *From: *Jordan Rupprecht <rupprecht at google.com>
>>> *Date: *Fri, May 10, 2019 at 12:58 PM
>>> *To: *Florian Hahn
>>> *Cc: *llvm-commits
>>>
>>> Looks like this causes some asan/msan crashes (or in some cases, test
>>>> failure/miscompiles). I'll see if I can get a crash with debug+asserts
>>>> enabled. In release mode, it's crashing during Machine InstCombiner/Live
>>>> Variable Analysis for different repros.
>>>>
>>>>
>>>> *From: *Florian Hahn via llvm-commits <llvm-commits at lists.llvm.org>
>>>> *Date: *Tue, May 7, 2019 at 9:45 AM
>>>> *To: * <llvm-commits at lists.llvm.org>
>>>>
>>>> Author: fhahn
>>>>> Date: Tue May 7 09:47:27 2019
>>>>> New Revision: 360171
>>>>>
>>>>> URL: http://llvm.org/viewvc/llvm-project?rev=360171&view=rev
>>>>> Log:
>>>>> [DAGCombiner] Avoid creating large tokenfactors in visitTokenFactor
>>>>>
>>>>> When simplifying TokenFactors, we potentially iterate over all
>>>>> operands of a large number of TokenFactors. This causes quadratic
>>>>> compile times in some cases and the large token factors cause
>>>>> additional
>>>>> scalability problems elsewhere.
>>>>>
>>>>> This patch adds some limits to the number of nodes explored for the
>>>>> cases mentioned above.
>>>>>
>>>>> Reviewers: niravd, spatel, craig.topper
>>>>>
>>>>> Reviewed By: niravd
>>>>>
>>>>> Differential Revision: https://reviews.llvm.org/D61397
>>>>>
>>>>> Modified:
>>>>> llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
>>>>>
>>>>> Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
>>>>> URL:
>>>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=360171&r1=360170&r2=360171&view=diff
>>>>>
>>>>> ==============================================================================
>>>>> --- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
>>>>> +++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Tue May 7
>>>>> 09:47:27 2019
>>>>> @@ -1792,8 +1792,9 @@ SDValue DAGCombiner::visitTokenFactor(SD
>>>>> TFs.push_back(N);
>>>>>
>>>>> // Iterate through token factors. The TFs grows when new token
>>>>> factors are
>>>>> - // encountered.
>>>>> - for (unsigned i = 0; i < TFs.size(); ++i) {
>>>>> + // encountered. Limit number of nodes to inline, to avoid quadratic
>>>>> compile
>>>>> + // times.
>>>>> + for (unsigned i = 0; i < TFs.size() && Ops.size() <= 2048; ++i) {
>>>>> SDNode *TF = TFs[i];
>>>>>
>>>>> // Check each of the operands.
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> llvm-commits mailing list
>>>>> llvm-commits at lists.llvm.org
>>>>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>>>>>
>>>>
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