[llvm-bugs] [Bug 33753] New: 3+ minutes is spent in ScalarEvolution on a tiny test

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=33753

            Bug ID: 33753
           Summary: 3+ minutes is spent in ScalarEvolution on a tiny test
           Product: new-bugs
           Version: unspecified
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: kcc at google.com
                CC: llvm-bugs at lists.llvm.org

on r307569

clang -cc1 -triple x86_64-unknown-linux-gnu  -O2  -emit-obj
slow-ScalarEvolution.cc

Most time is spent in ScalarEvolution::getAddExpr:

#24 0x000000000134118a in
llvm::ScalarEvolution::getAddExpr(llvm::SmallVectorImpl<llvm::SCEV const*>&,
llvm::SCEV::NoWrapFlags, unsigned int) ()
#25 0x000000000133f9a7 in
llvm::ScalarEvolution::getAddExpr(llvm::SmallVectorImpl<llvm::SCEV const*>&,
llvm::SCEV::NoWrapFlags, unsigned int) ()
#26 0x00000000013402d0 in
llvm::ScalarEvolution::getAddExpr(llvm::SmallVectorImpl<llvm::SCEV const*>&,
llvm::SCEV::NoWrapFlags, unsigned int) ()
#27 0x000000000134f5be in llvm::ScalarEvolution::createSCEV(llvm::Value*) ()
#28 0x000000000134bb01 in llvm::ScalarEvolution::getSCEV(llvm::Value*) ()
#29 0x0000000001a9271a in (anonymous
namespace)::LSRInstance::ChainInstruction(llvm::Instruction*,
llvm::Instruction*, llvm::SmallVectorImpl<(anonymous namespace)::ChainUsers>&)
()
#30 0x0000000001a81f7f in (anonymous
namespace)::LSRInstance::LSRInstance(llvm::Loop*, llvm::IVUsers&,
llvm::ScalarEvolution&, llvm::DominatorTree&, llvm::LoopInfo&,
llvm::TargetTransformInfo const&) ()
#31 0x0000000001a7ebdf in ReduceLoopStrength(llvm::Loop*, llvm::IVUsers&,
llvm::ScalarEvolution&, llvm::DominatorTree&, llvm::LoopInfo&,
llvm::TargetTransformInfo const&) ()
#32 0x0000000001307720 in llvm::LPPassManager::runOnFunction(llvm::Function&)
()


Found by an experimental clang-proto-fuzzer

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