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clang crashes under -O3 in llvm-project/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp:516: void {anonymous}::Formula::canonicalize(const llvm::Loop&): Assertion `!BaseRegs.empty() && "1*reg => reg, should not be needed."' failed. #49041

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haoxintu opened this issue Mar 23, 2021 · 2 comments
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clang crashes under -O3 in llvm-project/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp:516: void {anonymous}::Formula::canonicalize(const llvm::Loop&): Assertion `!BaseRegs.empty() && "1*reg => reg, should not be needed."' failed. #49041

haoxintu opened this issue Mar 23, 2021 · 2 comments
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bugzilla Issues migrated from bugzilla llvm:crash llvm:optimizations

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@haoxintu
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Bugzilla Link 49697
Version trunk
OS Linux
CC @oToToT

Extended Description

Hi all.

Clang crashes on the valid code under -O3. Note that this issue only occurs in the current trunk version of clang while released versions of clang handle it well.

$cat small.c
#include <stdint.h>
int a;
int8_t b;
void c() {
for (b = 8; b <= 6;)
;
int d = -4;
while (d < 20) {
d += 5;
int e = 7;
do {
int f = 7;
a = b;
while (f--)
for (b = 20; b <= 30; b++) {
int8_t *g = &b;
(*g -= a) || 0 > g < g;
}
} while (e--);
}
}

$clang -w -O3 small.c
clang: /home/haoxin/haoxin-data/dut-research/compilers/llvm-project/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp:516: void {anonymous}::Formula::canonicalize(const llvm::Loop&): Assertion `!BaseRegs.empty() && "1*reg => reg, should not be needed."' failed.
PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0. Program arguments: clang -w -c -O3 small.c

  1. parser at end of file
  2. Code generation
  3. Running pass 'Function Pass Manager' on module 'small.c'.
  4. Running pass 'Loop Pass Manager' on function '@c'
  5. Running pass 'Loop Strength Reduction' on basic block '%for.body11.6.1'
    #​0 0x00005629c94918ac llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x345f8ac)
    #​1 0x00005629c948f4e4 llvm::sys::RunSignalHandlers() (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x345d4e4)
    #​2 0x00005629c948f77b llvm::sys::CleanupOnSignal(unsigned long) (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x345d77b)
    #​3 0x00005629c93ec738 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
    #​4 0x00007f6a94406980 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x12980)
    #​5 0x00007f6a9302efb7 raise /build/glibc-S9d2JN/glibc-2.27/signal/../sysdeps/unix/sysv/linux/raise.c:51:0
    #​6 0x00007f6a93030921 abort /build/glibc-S9d2JN/glibc-2.27/stdlib/abort.c:81:0
    #​7 0x00007f6a9302048a __assert_fail_base /build/glibc-S9d2JN/glibc-2.27/assert/assert.c:89:0
    #​8 0x00007f6a93020502 (/lib/x86_64-linux-gnu/libc.so.6+0x30502)
    #​9 0x00005629c926a39a (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x323839a)
    #​10 0x00005629c9274c95 (anonymous namespace)::LSRInstance::GenerateReassociationsImpl((anonymous namespace)::LSRUse&, unsigned int, (anonymous namespace)::Formula const&, unsigned int, unsigned long, bool) LoopStrengthReduce.cpp:0:0
    #​11 0x00005629c9274d6d (anonymous namespace)::LSRInstance::GenerateReassociationsImpl((anonymous namespace)::LSRUse&, unsigned int, (anonymous namespace)::Formula const&, unsigned int, unsigned long, bool) LoopStrengthReduce.cpp:0:0
    #​12 0x00005629c927e57a (anonymous namespace)::LSRInstance::GenerateAllReuseFormulae() LoopStrengthReduce.cpp:0:0
    #​13 0x00005629c9287652 (anonymous namespace)::LSRInstance::LSRInstance(llvm::Loop*, llvm::IVUsers&, llvm::ScalarEvolution&, llvm::DominatorTree&, llvm::LoopInfo&, llvm::TargetTransformInfo const&, llvm::AssumptionCache&, llvm::TargetLibraryInfo&, llvm::MemorySSAUpdater*) LoopStrengthReduce.cpp:0:0
    #​14 0x00005629c928a267 ReduceLoopStrength(llvm::Loop*, llvm::IVUsers&, llvm::ScalarEvolution&, llvm::DominatorTree&, llvm::LoopInfo&, llvm::TargetTransformInfo const&, llvm::AssumptionCache&, llvm::TargetLibraryInfo&, llvm::MemorySSA*) LoopStrengthReduce.cpp:0:0
    #​15 0x00005629c928cdba (anonymous namespace)::LoopStrengthReduce::runOnLoop(llvm::Loop*, llvm::LPPassManager&) LoopStrengthReduce.cpp:0:0
    #​16 0x00005629c8521833 llvm::LPPassManager::runOnFunction(llvm::Function&) (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x24ef833)
    #​17 0x00005629c8c4eca4 llvm::FPPassManager::runOnFunction(llvm::Function&) (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x2c1cca4)
    #​18 0x00005629c8c4f7e9 llvm::FPPassManager::runOnModule(llvm::Module&) (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x2c1d7e9)
    #​19 0x00005629c8c4e5c1 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x2c1c5c1)
    #​20 0x00005629c975422b (anonymous namespace)::EmitAssemblyHelper::EmitAssemblyWithNewPassManager(clang::BackendAction, std::unique_ptr<llvm::raw_pwrite_stream, std::default_deletellvm::raw_pwrite_stream >) BackendUtil.cpp:0:0
    #​21 0x00005629c97574f5 clang::EmitBackendOutput(clang::DiagnosticsEngine&, clang::HeaderSearchOptions const&, clang::CodeGenOptions const&, clang::TargetOptions const&, clang::LangOptions const&, llvm::DataLayout const&, llvm::Module*, clang::BackendAction, std::unique_ptr<llvm::raw_pwrite_stream, std::default_deletellvm::raw_pwrite_stream >) (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x37254f5)
    #​22 0x00005629ca3d3816 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x43a1816)
    #​23 0x00005629caf38969 clang::ParseAST(clang::Sema&, bool, bool) (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x4f06969)
    #​24 0x00005629ca3d25d8 clang::CodeGenAction::ExecuteAction() (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x43a05d8)
    #​25 0x00005629c9d60ab9 clang::FrontendAction::Execute() (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x3d2eab9)
    #​26 0x00005629c9cfe6f1 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x3ccc6f1)
    #​27 0x00005629c9e28df0 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x3df6df0)
    #​28 0x00005629c70800f4 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x104e0f4)
    #​29 0x00005629c707c657 ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&) driver.cpp:0:0
    #​30 0x00005629c9bb00a5 void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<llvm::Optionalllvm::StringRef >, std::__cxx11::basic_string<char, std::char_traits, std::allocator >, bool) const::'lambda'()>(long) Job.cpp:0:0
    #​31 0x00005629c93ec8b2 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x33ba8b2)
    #​32 0x00005629c9bb13ec clang::driver::CC1Command::Execute(llvm::ArrayRef<llvm::Optionalllvm::StringRef >, std::__cxx11::basic_string<char, std::char_traits, std::allocator >, bool) const (.part.186) Job.cpp:0:0
    #​33 0x00005629c9b89309 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&) const (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x3b57309)
    #​34 0x00005629c9b89de7 clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*> >&) const (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x3b57de7)
    #​35 0x00005629c9b92c49 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*> >&) (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x3b60c49)
    #​36 0x00005629c6faaf8e main (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0xf78f8e)
    #​37 0x00007f6a93011bf7 __libc_start_main /build/glibc-S9d2JN/glibc-2.27/csu/../csu/libc-start.c:344:0
    #​38 0x00005629c707c0da _start (/media/haoxin/SeagateData/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin/clang-13+0x104a0da)
    clang-13: error: clang frontend command failed with exit code 134 (use -v to see invocation)
    clang version 13.0.0 (https://github.com/llvm/llvm-project 613157d)
    Target: x86_64-unknown-linux-gnu
    Thread model: posix
    InstalledDir: /home/haoxin/haoxin-data/dut-research/compilers/llvm-project/build-20210321/bin
    clang-13: note: diagnostic msg:

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang-13: note: diagnostic msg: /tmp/small-d37230.c
clang-13: note: diagnostic msg: /tmp/small-d37230.sh
clang-13: note: diagnostic msg:

Thanks,
Haoxin
@haoxintu
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This case also still crashes, too.

$clang -w -O3 samll.c
PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0. Program arguments: /home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14 -cc1 -triple x86_64-unknown-linux-gnu -emit-obj --mrelax-relocations -disable-free -main-file-name test.c -mrelocation-model static -mframe-pointer=none -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/home/haoxin/haoxin-data/test -resource-dir /home/haoxin/haoxin-data/compilers/llvm-project/build/lib/clang/14.0.0 -internal-isystem /home/haoxin/haoxin-data/compilers/llvm-project/build/lib/clang/14.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/9/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O3 -w -fdebug-compilation-dir=/home/haoxin/haoxin-data/test -ferror-limit 19 -fgnuc-version=4.2.1 -fcolor-diagnostics -vectorize-loops -vectorize-slp -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/test-d93eba.o -x c test.c

  1. parser at end of file
  2. Code generation
  3. Running pass 'Function Pass Manager' on module 'test.c'.
  4. Running pass 'Loop Pass Manager' on function '@c'
  5. Running pass 'Loop Strength Reduction' on basic block '%for.body11.6.3.1'
    #​0 0x000055b5d1d9b354 PrintStackTraceSignalHandler(void*) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x3b32354)
    #​1 0x000055b5d1d98a6e SignalHandler(int) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x3b2fa6e)
    #​2 0x00007f7fbdfb43c0 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x153c0)
    #​3 0x000055b5d0d09a92 llvm::ScalarEvolution::computeBlockDisposition(llvm::SCEV const*, llvm::BasicBlock const*) (.localalias) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x2aa0a92)
    #​4 0x000055b5d0d09619 llvm::ScalarEvolution::getBlockDisposition(llvm::SCEV const*, llvm::BasicBlock const*) (.localalias) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x2aa0619)
    #​5 0x000055b5d0d099dd llvm::ScalarEvolution::properlyDominates(llvm::SCEV const*, llvm::BasicBlock const*) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x2aa09dd)
    #​6 0x000055b5d1b53b4e (anonymous namespace)::LSRInstance::GenerateAllReuseFormulae() (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x38eab4e)
    #​7 0x000055b5d1b5ce69 (anonymous namespace)::LSRInstance::LSRInstance(llvm::Loop*, llvm::IVUsers&, llvm::ScalarEvolution&, llvm::DominatorTree&, llvm::LoopInfo&, llvm::TargetTransformInfo const&, llvm::AssumptionCache&, llvm::TargetLibraryInfo&, llvm::MemorySSAUpdater*) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x38f3e69)
    #​8 0x000055b5d1b60356 ReduceLoopStrength(llvm::Loop*, llvm::IVUsers&, llvm::ScalarEvolution&, llvm::DominatorTree&, llvm::LoopInfo&, llvm::TargetTransformInfo const&, llvm::AssumptionCache&, llvm::TargetLibraryInfo&, llvm::MemorySSA*) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x38f7356)
    #​9 0x000055b5d1b6298f (anonymous namespace)::LoopStrengthReduce::runOnLoop(llvm::Loop*, llvm::LPPassManager&) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x38f998f)
    #​10 0x000055b5d0c60a13 llvm::LPPassManager::runOnFunction(llvm::Function&) (.localalias) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x29f7a13)
    #​11 0x000055b5d1448c65 llvm::FPPassManager::runOnFunction(llvm::Function&) (.localalias) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x31dfc65)
    #​12 0x000055b5d1448ea9 llvm::FPPassManager::runOnModule(llvm::Module&) (.localalias) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x31dfea9)
    #​13 0x000055b5d1449f92 llvm::legacy::PassManagerImpl::run(llvm::Module&) (.localalias) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x31e0f92)
    #​14 0x000055b5d20df82a (anonymous namespace)::EmitAssemblyHelper::EmitAssemblyWithNewPassManager(clang::BackendAction, std::unique_ptr<llvm::raw_pwrite_stream, std::default_deletellvm::raw_pwrite_stream >) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x3e7682a)
    #​15 0x000055b5d20e135d clang::EmitBackendOutput(clang::DiagnosticsEngine&, clang::HeaderSearchOptions const&, clang::CodeGenOptions const&, clang::TargetOptions const&, clang::LangOptions const&, llvm::StringRef, llvm::Module*, clang::BackendAction, std::unique_ptr<llvm::raw_pwrite_stream, std::default_deletellvm::raw_pwrite_stream >) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x3e7835d)
    #​16 0x000055b5d2f4520f clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x4cdc20f)
    #​17 0x000055b5d3cb06b9 clang::ParseAST(clang::Sema&, bool, bool) (.localalias) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x5a476b9)
    #​18 0x000055b5d2f43d48 clang::CodeGenAction::ExecuteAction() (.localalias) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x4cdad48)
    #​19 0x000055b5d27d7ba9 clang::FrontendAction::Execute() (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x456eba9)
    #​20 0x000055b5d276d2be clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (.localalias) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x45042be)
    #​21 0x000055b5d28b69c0 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x464d9c0)
    #​22 0x000055b5cf5ab6bd cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x13426bd)
    #​23 0x000055b5cf5a7a08 ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&) (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x133ea08)
    #​24 0x000055b5cf4dcac9 main (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x1273ac9)
    #​25 0x00007f7fbda340b3 __libc_start_main /build/glibc-eX1tMB/glibc-2.31/csu/../csu/libc-start.c:342:3
    #​26 0x000055b5cf5a757e _start (/home/haoxin/haoxin-data/compilers/llvm-project/build/bin/clang-14+0x133e57e)
    clang-14: error: unable to execute command: Segmentation fault (core dumped)
    clang-14: error: clang frontend command failed due to signal (use -v to see invocation)
    clang version 14.0.0 (https://github.com/llvm/llvm-project 5541a05)
    Target: x86_64-unknown-linux-gnu
    Thread model: posix
    InstalledDir: /home/haoxin/haoxin-data/compilers/llvm-project/build/bin
    clang-14: note: diagnostic msg:

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang-14: note: diagnostic msg: /tmp/test-1fdfa4.c
clang-14: note: diagnostic msg: /tmp/test-1fdfa4.sh
clang-14: note: diagnostic msg:

@llvmbot llvmbot transferred this issue from llvm/llvm-bugzilla-archive Dec 11, 2021
@fhahn
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fhahn commented May 10, 2022

It looks like this has been fixed recently. It passes with current main and crashes with clang 14.0: https://godbolt.org/z/YcaxExesf

I extracted the IR before LoopStrengthReduce. It also crashes when running -loop-reduce with opt 14.0 and passes with current main: https://llvm.godbolt.org/z/GxoWbYz6d

@fhahn fhahn closed this as completed May 10, 2022
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