[SLP]Generalize cost model.

[ABataev]

Summary

Generalized the cost model estimation. Improved cost model estimation
for repeated scalars (no need to count their cost anymore), improved

cost model for extractelement instructions.

cpu2017

511.povray_r             0.57
520.omnetpp_r           -0.98
521.wrf_r               -0.01
525.x264_r               3.59 <+
526.blender_r           -0.12
531.deepsjeng_r         -0.07
538.imagick_r           -1.42

Geometric mean: 0.21

[ABataev]

Rebase

[ABataev]

Rebase

[RKSimon]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5278–5279

I->getOperand(OpIdx) == Op0;

5278–5279

auto *Op = I->getOperand(OpIdx);

5281

true?

[ABataev]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5281

Here is my idea. Generally speaking, here we can have only undef/poison or just a pointer (as part of getelementpr node) currently (maybe, need to add an assert). I thought that because of that we can treat its (virtual) operand as power-of-2, since it can be any value. Thoughts?

[ABataev]

Address comments

[ABataev]

Rebase

[ABataev]

Ping!

[ABataev]

Rebase. Ping!

[ABataev]

Ping!

[RKSimon]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5578

Is this purely compile time saving?

5605

Can't we directly initialize Operands from PHI-> incoming_values()? Or even create a ArrayRef<> from it?

5654

We're going to lose the recent scalarization cost improvement here :-(

5851

Would isa<UnaryOperator> ? 0 : 1 be better?

5918

Why do you avoid allowing uniform as well? Can't you just use getOperandInfo(VL, 0)..getNoProps() below ?

[ABataev]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5578

Replaced by 0, since it does not matter.

5605

operand_value returns llvm::Use, Operands list requires Value *. Did not find better way to do it.

5918

Just missed this change, will fix.

[ABataev]

Rebase, address comments

[ABataev]

Ping!

[RKSimon]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5281

Still not sure about this - this undef case is fine, but the GEP I can imagine might not work in all special cases.

How good is return isa<UndefValue>(V); instead?

5283

return isa<UndefValue>(V)?

[RKSimon]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5846

Why didn't we ever use getGEPCost?

[ABataev]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5846

It originally used add cost for GEPs, most probably there were getGEPCost. Plus, I don't see target-specific getGEPCost implementations, looks like we have only base one.
We could try to switch to getGEPCost but it must be in a separate patch.

[ABataev]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5281

GetElementPtr may have just a pointer, which is not a GEP instructions.
Say, we have this:

void @foo(ptr %v) {
...
load %v
%n = getelementptr i32, ptr v, 1
load %n
...
}

and we may have a ПУЗ node which includes {%v, %n}. Here %v is not a GEP though still part of the GEP node and we consider as gentlementptr ptr %v, 0.

[RKSimon]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5281

OK - so for GEPs you're saying that either the operands will be constant or a phi of constants?

5609

I'm sorry but I had to revert the ScalarizationOverheadBuilder code - this needs reverting back to the older version

[ABataev]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5281

No (or I missed something). I mean, that except for GEPs we may have just a non-ПУЗ pointer value and we just treat it as getelementptr, 0. But we return true if we have just a value (which is GEP with offset 0) and all other GEPs are power-of-2 constant ints.

[ABataev]

Rebase

[ABataev]

Rebase

[RKSimon]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5743

So CommonCost is only applied if (!MinBWs.count(VL0) || VecTy != SrcVecTy) ?

[ABataev]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5743

Yeah, looks like should not ignore it here, since it includes the shuffle cost.

[ABataev]

Address comments

[vdmitrie]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5568

Do you have a specific reason to keep this as lambda(lambda(...),lambda(...)) design?
I mean this would look much better if you make one more step and outline this into a separate class (for example CostDifferentiator) with dedicated methods instead of stuffing code with tons of lambdas.

[ABataev]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5568

It will still have lambdas for each particular opcode

[vdmitrie]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5568

Why? It is not prohibited to have dedicated method in the class for each particular opcode.

[ABataev]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5568

It still will be a switch with functions calls, which have the pretty similar loops and other processing. This what exactly I want to avoid - duplicate of the code.

[vdmitrie]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5568

I can't agree with statement that it will be a duplication of code. Organized differently - yes.
IMO it's always worth investing time in developing a better interface.

[ABataev]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5568

I don't quite understand what you're proposing. Provide at least a small example.

[vdmitrie]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5568

Just a sketch:

sample.txt6 KBDownload

[RKSimon]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5578

I'm not sure if we need to pull them out into separate methods if they're just being called once. But it would help a little for readability if the lambdas weren't embedded in the GetCostDiff calls themselves.

So:

auto ScalarEltCost = [](unsigned Idx)  {...};
auto VectorCost = [](InstructionCost CommonCost)  {...};
return GetCostDiff(ScalarEltCost, VectorCost);

[ABataev]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5578

I prefer this approach. I don't want to introduce virtual member functions. Without virtual functions the only approach - generic lambda, which increases codesize.

[ABataev]

Address comments, formatting

[vdmitrie]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5578

What problem you see with virtual class here?
Using named lambdas instead of unnamed ones is definitely better. But essentially it anyway remains a C-style programming, just using C++ syntax. You are also making it very difficult to customize this code downstream. If that is the goal - okay, got it.

[ABataev]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5578

It usually increases compile time.
Why it is hard to customize it?

[vdmitrie]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5578

It usually increases compile time.

Use of C++ has its costs. I'm pretty sure the increase will be unmeasurable.
I believe that if invest a bit more time into this something better can be found.

Why it is hard to customize it?

because this will require replacing a lambda rather than just make a descendant with custom functionality that might fully or partially reuse its base. I'm not saying it is impossible to do that with lambdas. It will just be significantly more ugly: create another lambda with the original one in capture list...

[ABataev]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5578

I though about templated lambda instead of virtual class, but it will implicitly copied across all cases.

[RKSimon]

LGTM

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

5578

I don't want to stop this conversation as I'd dearly like to see the SLP code be easier to understand as its complexity/density puts off a lot of people from contributing - but we need somewhere better to discuss this than on a patch review thread.

5594–5601

It looks like theres a clang-format change across this entire switch statement that ideally needs pre-committing to reduce the patch whitespace/indentation diff?

[fmayer]

This seems to have an MSAN error: https://lab.llvm.org/buildbot/#/builders/74/builds/14338/steps/13/logs/stdio

FAIL: LLVM :: Transforms/SLPVectorizer/X86/crash_7zip.ll (57172 of 68894)
******************** TEST 'LLVM :: Transforms/SLPVectorizer/X86/crash_7zip.ll' FAILED ********************
Script:
--
: 'RUN: at line 2';   /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build_msan/bin/opt < /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/test/Transforms/SLPVectorizer/X86/crash_7zip.ll -slp-vectorizer -dce -S -mtriple=x86_64-apple-macosx10.8.0 -mcpu=corei7 | /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build_msan/bin/FileCheck /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/test/Transforms/SLPVectorizer/X86/crash_7zip.ll
--
Exit Code: 2
Command Output (stderr):
--
==3579288==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x56270dbbe918 in operator() /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:6569:19
    #1 0x56270dbbe918 in llvm::InstructionCost llvm::function_ref<llvm::InstructionCost (unsigned int)>::callback_fn<llvm::slpvectorizer::BoUpSLP::getEntryCost(llvm::slpvectorizer::BoUpSLP::TreeEntry const*, llvm::ArrayRef<llvm::Value*>)::$_63>(long, unsigned int) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/ADT/STLFunctionalExtras.h:45:12
    #2 0x56270dafc992 in operator() /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/ADT/STLFunctionalExtras.h:68:12
    #3 0x56270dafc992 in llvm::slpvectorizer::BoUpSLP::getEntryCost(llvm::slpvectorizer::BoUpSLP::TreeEntry const*, llvm::ArrayRef<llvm::Value*>)::$_58::operator()(llvm::function_ref<llvm::InstructionCost (unsigned int)>, llvm::function_ref<llvm::InstructionCost (llvm::InstructionCost)>) const /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:6336:29
    #4 0x56270daeeb36 in llvm::slpvectorizer::BoUpSLP::getEntryCost(llvm::slpvectorizer::BoUpSLP::TreeEntry const*, llvm::ArrayRef<llvm::Value*>) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
    #5 0x56270db033d8 in llvm::slpvectorizer::BoUpSLP::getTreeCost(llvm::ArrayRef<llvm::Value*>) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:7273:25
    #6 0x56270db4bb38 in llvm::SLPVectorizerPass::vectorizeStoreChain(llvm::ArrayRef<llvm::Value*>, llvm::slpvectorizer::BoUpSLP&, unsigned int, unsigned int) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:10379:28
    #7 0x56270db4eadb in llvm::SLPVectorizerPass::vectorizeStores(llvm::ArrayRef<llvm::StoreInst*>, llvm::slpvectorizer::BoUpSLP&) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:10521:13
    #8 0x56270db4279c in operator() /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:12807:18
    #9 0x56270db4279c in callback_fn<(lambda at /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:12806:9)> /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/ADT/STLFunctionalExtras.h:45:12
    #10 0x56270db4279c in operator() /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/ADT/STLFunctionalExtras.h:68:12
    #11 0x56270db4279c in tryToVectorizeSequence<llvm::StoreInst> /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:12192:9
    #12 0x56270db4279c in llvm::SLPVectorizerPass::vectorizeStoreChains(llvm::slpvectorizer::BoUpSLP&) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:12804:16
    #13 0x56270db3f9f7 in llvm::SLPVectorizerPass::runImpl(llvm::Function&, llvm::ScalarEvolution*, llvm::TargetTransformInfo*, llvm::TargetLibraryInfo*, llvm::AAResults*, llvm::LoopInfo*, llvm::DominatorTree*, llvm::AssumptionCache*, llvm::DemandedBits*, llvm::OptimizationRemarkEmitter*) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:10332:18
    #14 0x56270db3e0b0 in llvm::SLPVectorizerPass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:10267:18
    #15 0x56270ddc2a21 in llvm::detail::PassModel<llvm::Function, llvm::SLPVectorizerPass, llvm::PreservedAnalyses, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/IR/PassManagerInternal.h:88:17
    #16 0x56270bf43ae0 in llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/IR/PassManager.h:517:40
    #17 0x56270779e201 in llvm::detail::PassModel<llvm::Function, llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>, llvm::PreservedAnalyses, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/IR/PassManagerInternal.h:88:17
    #18 0x56270bf4fc31 in llvm::ModuleToFunctionPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/IR/PassManager.cpp:124:38
    #19 0x56270779db71 in llvm::detail::PassModel<llvm::Module, llvm::ModuleToFunctionPassAdaptor, llvm::PreservedAnalyses, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/IR/PassManagerInternal.h:88:17
    #20 0x56270bf40fb0 in llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/IR/PassManager.h:517:40
    #21 0x562706b90baf in llvm::runPassPipeline(llvm::StringRef, llvm::Module&, llvm::TargetMachine*, llvm::TargetLibraryInfoImpl*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::StringRef, llvm::ArrayRef<llvm::StringRef>, llvm::ArrayRef<llvm::PassPlugin>, llvm::opt_tool::OutputKind, llvm::opt_tool::VerifierKind, bool, bool, bool, bool, bool, bool) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/tools/opt/NewPMDriver.cpp:497:7
    #22 0x562706bc0377 in main /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/tools/opt/opt.cpp:784:12
    #23 0x7ff7be184d8f  (/lib/x86_64-linux-gnu/libc.so.6+0x29d8f) (BuildId: 69389d485a9793dbe873f0ea2c93e02efaa9aa3d)
    #24 0x7ff7be184e3f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e3f) (BuildId: 69389d485a9793dbe873f0ea2c93e02efaa9aa3d)
    #25 0x562706af7664 in _start (/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build_msan/bin/opt+0x386a664)
SUMMARY: MemorySanitizer: use-of-uninitialized-value /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:6569:19 in operator()
Exiting
FileCheck error: '<stdin>' is empty.
FileCheck command line:  /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build_msan/bin/FileCheck /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/test/Transforms/SLPVectorizer/X86/crash_7zip.ll

[ABataev]

In D115757#3866816, @fmayer wrote:

This seems to have an MSAN error: https://lab.llvm.org/buildbot/#/builders/74/builds/14338/steps/13/logs/stdio

FAIL: LLVM :: Transforms/SLPVectorizer/X86/crash_7zip.ll (57172 of 68894)
******************** TEST 'LLVM :: Transforms/SLPVectorizer/X86/crash_7zip.ll' FAILED ********************
Script:
--
: 'RUN: at line 2';   /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build_msan/bin/opt < /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/test/Transforms/SLPVectorizer/X86/crash_7zip.ll -slp-vectorizer -dce -S -mtriple=x86_64-apple-macosx10.8.0 -mcpu=corei7 | /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build_msan/bin/FileCheck /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/test/Transforms/SLPVectorizer/X86/crash_7zip.ll
--
Exit Code: 2
Command Output (stderr):
--
==3579288==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x56270dbbe918 in operator() /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:6569:19
    #1 0x56270dbbe918 in llvm::InstructionCost llvm::function_ref<llvm::InstructionCost (unsigned int)>::callback_fn<llvm::slpvectorizer::BoUpSLP::getEntryCost(llvm::slpvectorizer::BoUpSLP::TreeEntry const*, llvm::ArrayRef<llvm::Value*>)::$_63>(long, unsigned int) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/ADT/STLFunctionalExtras.h:45:12
    #2 0x56270dafc992 in operator() /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/ADT/STLFunctionalExtras.h:68:12
    #3 0x56270dafc992 in llvm::slpvectorizer::BoUpSLP::getEntryCost(llvm::slpvectorizer::BoUpSLP::TreeEntry const*, llvm::ArrayRef<llvm::Value*>)::$_58::operator()(llvm::function_ref<llvm::InstructionCost (unsigned int)>, llvm::function_ref<llvm::InstructionCost (llvm::InstructionCost)>) const /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:6336:29
    #4 0x56270daeeb36 in llvm::slpvectorizer::BoUpSLP::getEntryCost(llvm::slpvectorizer::BoUpSLP::TreeEntry const*, llvm::ArrayRef<llvm::Value*>) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
    #5 0x56270db033d8 in llvm::slpvectorizer::BoUpSLP::getTreeCost(llvm::ArrayRef<llvm::Value*>) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:7273:25
    #6 0x56270db4bb38 in llvm::SLPVectorizerPass::vectorizeStoreChain(llvm::ArrayRef<llvm::Value*>, llvm::slpvectorizer::BoUpSLP&, unsigned int, unsigned int) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:10379:28
    #7 0x56270db4eadb in llvm::SLPVectorizerPass::vectorizeStores(llvm::ArrayRef<llvm::StoreInst*>, llvm::slpvectorizer::BoUpSLP&) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:10521:13
    #8 0x56270db4279c in operator() /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:12807:18
    #9 0x56270db4279c in callback_fn<(lambda at /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:12806:9)> /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/ADT/STLFunctionalExtras.h:45:12
    #10 0x56270db4279c in operator() /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/ADT/STLFunctionalExtras.h:68:12
    #11 0x56270db4279c in tryToVectorizeSequence<llvm::StoreInst> /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:12192:9
    #12 0x56270db4279c in llvm::SLPVectorizerPass::vectorizeStoreChains(llvm::slpvectorizer::BoUpSLP&) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:12804:16
    #13 0x56270db3f9f7 in llvm::SLPVectorizerPass::runImpl(llvm::Function&, llvm::ScalarEvolution*, llvm::TargetTransformInfo*, llvm::TargetLibraryInfo*, llvm::AAResults*, llvm::LoopInfo*, llvm::DominatorTree*, llvm::AssumptionCache*, llvm::DemandedBits*, llvm::OptimizationRemarkEmitter*) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:10332:18
    #14 0x56270db3e0b0 in llvm::SLPVectorizerPass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:10267:18
    #15 0x56270ddc2a21 in llvm::detail::PassModel<llvm::Function, llvm::SLPVectorizerPass, llvm::PreservedAnalyses, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/IR/PassManagerInternal.h:88:17
    #16 0x56270bf43ae0 in llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/IR/PassManager.h:517:40
    #17 0x56270779e201 in llvm::detail::PassModel<llvm::Function, llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>, llvm::PreservedAnalyses, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/IR/PassManagerInternal.h:88:17
    #18 0x56270bf4fc31 in llvm::ModuleToFunctionPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/IR/PassManager.cpp:124:38
    #19 0x56270779db71 in llvm::detail::PassModel<llvm::Module, llvm::ModuleToFunctionPassAdaptor, llvm::PreservedAnalyses, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/IR/PassManagerInternal.h:88:17
    #20 0x56270bf40fb0 in llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/IR/PassManager.h:517:40
    #21 0x562706b90baf in llvm::runPassPipeline(llvm::StringRef, llvm::Module&, llvm::TargetMachine*, llvm::TargetLibraryInfoImpl*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::StringRef, llvm::ArrayRef<llvm::StringRef>, llvm::ArrayRef<llvm::PassPlugin>, llvm::opt_tool::OutputKind, llvm::opt_tool::VerifierKind, bool, bool, bool, bool, bool, bool) /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/tools/opt/NewPMDriver.cpp:497:7
    #22 0x562706bc0377 in main /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/tools/opt/opt.cpp:784:12
    #23 0x7ff7be184d8f  (/lib/x86_64-linux-gnu/libc.so.6+0x29d8f) (BuildId: 69389d485a9793dbe873f0ea2c93e02efaa9aa3d)
    #24 0x7ff7be184e3f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e3f) (BuildId: 69389d485a9793dbe873f0ea2c93e02efaa9aa3d)
    #25 0x562706af7664 in _start (/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build_msan/bin/opt+0x386a664)
SUMMARY: MemorySanitizer: use-of-uninitialized-value /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:6569:19 in operator()
Exiting
FileCheck error: '<stdin>' is empty.
FileCheck command line:  /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build_msan/bin/FileCheck /b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/test/Transforms/SLPVectorizer/X86/crash_7zip.ll

It was already reverted and then committed back with a fix.

[fmayer]

In D115757#3866833, @ABataev wrote:

It was already reverted and then committed back with a fix.

Sorry about that, I missed the revert line, I only skimmed the comments. Thanks!