[llvm-dev] help please: how to sort the contents of a "SymbolTableListTraits<GlobalVariable>"?
Mehdi Amini via llvm-dev
llvm-dev at lists.llvm.org
Thu Aug 4 12:13:05 PDT 2016
> On Aug 4, 2016, at 11:27 AM, Abe Skolnik via llvm-dev <llvm-dev at lists.llvm.org> wrote:
>
> Dear sir,
>
> Thanks for your reply. I apologize for taking a few days to reply.
>
>
>> Crashed how?
>
> Please see the below.
>
>
>> Have you turned on ASan?
>
> Not yet, but thanks for the suggestion. I guess I will try to rebuild my modified Clang+LLVM with addr. san. and see what happens.
>
>
>> I recommend attaching a minimal reproduction...
>
> Well, since I`m hacking on LLVM itself, this is not 100% trivial. I will explain.
>
> The first hurdle I had to overcome was the fact that the "GlobalVariable" class had an explicitly-deleted copy ctor and no move ctor. I dealt with this by writing a copy ctor; I`ll paste that in below.
>
> A perhaps-important point is that I don`t know _why_ the "GlobalVariable" class had an explicitly-deleted copy ctor and no move ctor. As an experiment, I moved forward with the hypothesis that this was simply because neither was needed at the time and the default [i.e. compiler-inserted] copy ctor would have been wrong. I hope the one _I_ wrote is _right_. ;-)
>
>
>> I assume you can reproduce this in a unit test?
>
> Well, it doesn`t take a long program-under-compilation to make this fail. As before, I will paste something in after my sign-off.
>
>
> Regards,
>
> Abe
>
>
>
>
>
> ----- added near the end of "OptimizeGlobalVars" in "llvm/lib/Transforms/IPO/GlobalOpt.cpp", amongst many other things I added to that routine -----
>
> struct GV_alignment_comparator {
> bool operator()(const GlobalVariable& L, const GlobalVariable& R) {
> return L.getAlignment() < R.getAlignment();
> }
> };
>
> if (unsorted) {
> M.getGlobalList().sort( GV_alignment_comparator() );
The issue is that the “sort” method of iplist is delegating a bunch of things to SymbolTableListTraits, and the later makes some assumption that are broken in this case.
The offending path is:
1) iplist:sort() wANTS to split the list in two
2) it creates a new empty list, and tries to splice a subpart of the existing list into the new one:
// Split the list into two.
iplist RightHalf;
RightHalf.splice(RightHalf.begin(), *this, Center, end());
3) split will call back into: SymbolTableListTraits::transferNodesFromList. Unfortunately this assumes that the list is owned by a Module (see SymbolTableListTraits ::getListOwner())
This obviously breaks badly in this case.
Note: I don’t know why you needed a copy/move ctor for global value, I was able to build with your “patch” to GlobalOpt.cpp without changing anything else.
—
Mehdi
> Changed = true;
> }
>
>
>
> ----- added to "llvm/lib/IR/Globals.cpp" [and commented out the relevant deletion in "llvm/include/llvm/IR/GlobalVariable.h"] -----
>
> GlobalVariable::GlobalVariable(const GlobalVariable& GV) : GlobalVariable( GV.getValueType(), GV.isConstant(), GV.getLinkage() ) { // copy ctor
> copyAttributesFrom(&GV);
> }
>
>
>
>
>
> main_with_3_globals.c
> ---------------------
>
> int foo;
> char bar;
> long baz;
>
> int main(){return foo;}
>
>
>
>
>
>
>
>
>
>
> ----- error dump from compiler driver -----
>
>> ../build_003/bin/clang main_with_3_globals.c -O3
>
> Abe was here: max. profitable alignment: 16
>
> Abe was here: found a global value that DOES have a name [“foo”],
> with alignment 4,
> no named section [double-check: should be empty string: “”],
> which is a pointer to a NON-array
> and with pointee type getTypeStoreSize -> 4
>
> Abe was here: found a global value that DOES have a name [“bar”],
> with alignment 1,
> no named section [double-check: should be empty string: “”],
> which is a pointer to a NON-array
> and with pointee type getTypeStoreSize -> 1
>
> Abe was here: found a global value that DOES have a name [“baz”],
> with alignment 8,
> no named section [double-check: should be empty string: “”],
> which is a pointer to a NON-array
> and with pointee type getTypeStoreSize -> 8
>
> ===== Abe was here: the globals above are NOT in ascending-alignment order. =====
> 0 clang-3.9 0x0000000002853ebc llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 60
> 1 clang-3.9 0x00000000028543a9
> 2 clang-3.9 0x0000000002852a83 llvm::sys::RunSignalHandlers() + 131
> 3 clang-3.9 0x00000000028546f4
> 4 libpthread.so.0 0x00007fc595318330
> 5 clang-3.9 0x00000000027fbe12 llvm::StringMapImpl::LookupBucketFor(llvm::StringRef) + 466
> 6 clang-3.9 0x0000000002320fa4
> 7 clang-3.9 0x0000000002320a10 llvm::ValueSymbolTable::reinsertValue(llvm::Value*) + 112
> 8 clang-3.9 0x00000000022f0551 llvm::SymbolTableListTraits<llvm::GlobalVariable>::transferNodesFromList(llvm::SymbolTableListTraits<llvm::GlobalVariable>&, llvm::ilist_iterator<llvm::GlobalVariable>, llvm::ilist_iterator<llvm::GlobalVariable>) + 273
> 9 clang-3.9 0x00000000023b1fd9
> 10 clang-3.9 0x00000000023b1c45
> 11 clang-3.9 0x00000000023a8e40
> 12 clang-3.9 0x000000000239e77c
> 13 clang-3.9 0x000000000239d88e
> 14 clang-3.9 0x00000000023a9f8c
> 15 clang-3.9 0x00000000022ac02a
> 16 clang-3.9 0x00000000022abb56 llvm::legacy::PassManagerImpl::run(llvm::Module&) + 342
> 17 clang-3.9 0x00000000022ac541 llvm::legacy::PassManager::run(llvm::Module&) + 33
> 18 clang-3.9 0x0000000002adf7c5
> 19 clang-3.9 0x0000000002adeda6 clang::EmitBackendOutput(clang::DiagnosticsEngine&, 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_delete<llvm::raw_pwrite_stream> >) + 150
> 20 clang-3.9 0x00000000035d622f
> 21 clang-3.9 0x0000000004259504 clang::ParseAST(clang::Sema&, bool, bool) + 820
> 22 clang-3.9 0x00000000030f011a clang::ASTFrontendAction::ExecuteAction() + 314
> 23 clang-3.9 0x00000000035d4bf5 clang::CodeGenAction::ExecuteAction() + 2357
> 24 clang-3.9 0x00000000030efc00 clang::FrontendAction::Execute() + 112
> 25 clang-3.9 0x0000000003094c81 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) + 1025
> 26 clang-3.9 0x0000000003241ba1 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) + 1473
> 27 clang-3.9 0x0000000000c33bc8 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) + 920
> 28 clang-3.9 0x0000000000c27c2a
> 29 clang-3.9 0x0000000000c26ae2 main + 2642
> 30 libc.so.6 0x00007fc593e80f45 __libc_start_main + 245
> 31 clang-3.9 0x0000000000c25f44
> Stack dump:
> 0. Program arguments: /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/build_003/bin/clang-3.9 -cc1 -triple x86_64-unknown-linux-gnu -emit-obj -disable-free -main-file-name main_with_3_globals.c -mrelocation-model static -mthread-model posix -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -momit-leaf-frame-pointer -dwarf-column-info -debugger-tuning=gdb -resource-dir /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/build_003/bin/../lib/clang/3.9.0 -internal-isystem /usr/local/include -internal-isystem /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/build_003/bin/../lib/clang/3.9.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O3 -fdebug-compilation-dir /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/tmp -ferror-limit 19 -fmessage-length 144 -fobjc-runtime=gcc -fdiagnostics-show-option -fcolor-diagnostics -vectorize-loops -vectorize-slp -o /tmp/main_with_3_globals-cef92e.o -x c main_with_3_globals.c
> 1. <eof> parser at end of file
> 2. Per-module optimization passes
> 3. Running pass 'Global Variable Optimizer' on module 'main_with_3_globals.c'.
> clang-3.9: error: unable to execute command: Segmentation fault
> clang-3.9: error: clang frontend command failed due to signal (use -v to see invocation)
> clang version 3.9.0
> Target: x86_64-unknown-linux-gnu
> Thread model: posix
> InstalledDir: /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/tmp/../build_003/bin
> clang-3.9: 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-3.9: note: diagnostic msg:
> ********************
>
> PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
> Preprocessed source(s) and associated run script(s) are located at:
> clang-3.9: note: diagnostic msg: /tmp/main_with_3_globals-841619.c
> clang-3.9: note: diagnostic msg: /tmp/main_with_3_globals-841619.sh
> clang-3.9: note: diagnostic msg:
>
> ********************
>
>
>
>
> GDB backtrace from the "-cc1" part of another run of the same-as-the-preceding compilation attempt
> --------------------------------------------------------------------------------------------------
>
> Program received signal SIGSEGV, Segmentation fault.
> 0x00000000027fbe12 in llvm::StringMapImpl::LookupBucketFor (this=0x82f00e8, Name=...)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/Support/StringMap.cpp:102
> 102 } else if (LLVM_LIKELY(HashTable[BucketNo] == FullHashValue)) {
> (gdb) bt
> #0 0x00000000027fbe12 in llvm::StringMapImpl::LookupBucketFor (this=0x82f00e8, Name=...)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/Support/StringMap.cpp:102
> #1 0x0000000002320fa4 in llvm::StringMap<llvm::Value*, llvm::MallocAllocator>::insert (this=0x82f00e8, KeyValue=0x8312cb0)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/include/llvm/ADT/StringMap.h:345
> #2 0x0000000002320a10 in llvm::ValueSymbolTable::reinsertValue (this=0x82f00e8, V=0x830cfd8)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/IR/ValueSymbolTable.cpp:59
> #3 0x00000000022f0551 in llvm::SymbolTableListTraits<llvm::GlobalVariable>::transferNodesFromList (this=0x7fffffffabd8, L2=..., first=...,
> last=...)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/IR/SymbolTableListTraitsImpl.h:102
> #4 0x00000000023b1fd9 in llvm::iplist<llvm::GlobalVariable, llvm::SymbolTableListTraits<llvm::GlobalVariable> >::transfer (
> this=0x7fffffffabd8, position=..., L2=..., first=..., last=...)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/include/llvm/ADT/ilist.h:532
> #5 0x00000000023b1c45 in llvm::iplist<llvm::GlobalVariable, llvm::SymbolTableListTraits<llvm::GlobalVariable> >::splice (this=0x7fffffffabd8,
> where=..., L2=..., first=..., last=...)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/include/llvm/ADT/ilist.h:587
> #6 0x00000000023a8e40 in llvm::iplist<llvm::GlobalVariable, llvm::SymbolTableListTraits<llvm::GlobalVariable> >::sort<OptimizeGlobalVars(llvm::Module&, llvm::TargetLibraryInfo*, llvm::function_ref<llvm::DominatorTree& (llvm::Function&)>, llvm::SmallSet<llvm::Comdat const*, 8u, std::less<llvm::Comdat const*> >&)::GV_alignment_comparator>(OptimizeGlobalVars(llvm::Module&, llvm::TargetLibraryInfo*, llvm::function_ref<llvm::DominatorTree& (llvm::Function&)>, llvm::SmallSet<llvm::Comdat const*, 8u, std::less<llvm::Comdat const*> >&)::GV_alignment_comparator) (
> this=0x82b1f98, comp=...)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/include/llvm/ADT/ilist.h:632
> #7 0x000000000239e77c in OptimizeGlobalVars(llvm::Module&, llvm::TargetLibraryInfo*, llvm::function_ref<llvm::DominatorTree& (llvm::Function&)>, llvm::SmallSet<llvm::Comdat const*, 8u, std::less<llvm::Comdat const*> >&) (M=..., TLI=0x8293860, LookupDomTree=...,
> NotDiscardableComdats=...)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/Transforms/IPO/GlobalOpt.cpp:2199
> #8 0x000000000239d88e in optimizeGlobalsInModule(llvm::Module&, llvm::DataLayout const&, llvm::TargetLibraryInfo*, llvm::function_ref<llvm::DominatorTree& (llvm::Function&)>) (M=..., DL=..., TLI=0x8293860, LookupDomTree=...)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/Transforms/IPO/GlobalOpt.cpp:2655
> #9 0x00000000023a9f8c in (anonymous namespace)::GlobalOptLegacyPass::runOnModule (this=0x8294f10, M=...)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/Transforms/IPO/GlobalOpt.cpp:2705
> #10 0x00000000022ac02a in (anonymous namespace)::MPPassManager::runOnModule (this=0x831de40, M=...)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/IR/LegacyPassManager.cpp:1603
> #11 0x00000000022abb56 in llvm::legacy::PassManagerImpl::run (this=0x83237d0, M=...)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/IR/LegacyPassManager.cpp:1706
> #12 0x00000000022ac541 in llvm::legacy::PassManager::run (this=0x7fffffffb500, M=...)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/IR/LegacyPassManager.cpp:1737
> #13 0x0000000002adf7c5 in (anonymous namespace)::EmitAssemblyHelper::EmitAssembly (this=0x7fffffffb7a8, Action=clang::Backend_EmitObj, OS=...)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/lib/CodeGen/BackendUtil.cpp:734
> #14 0x0000000002adeda6 in clang::EmitBackendOutput (Diags=..., CGOpts=..., TOpts=..., LOpts=..., TDesc=..., M=0x82b1f90,
> Action=clang::Backend_EmitObj, OS=...)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/lib/CodeGen/BackendUtil.cpp:751
> #15 0x00000000035d622f in clang::BackendConsumer::HandleTranslationUnit (this=0x82b1a80, C=...)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/lib/CodeGen/CodeGenAction.cpp:179
> #16 0x0000000004259504 in clang::ParseAST (S=..., PrintStats=false, SkipFunctionBodies=false)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/lib/Parse/ParseAST.cpp:167
> #17 0x00000000030f011a in clang::ASTFrontendAction::ExecuteAction (this=0x8297f20)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/lib/Frontend/FrontendAction.cpp:556
> #18 0x00000000035d4bf5 in clang::CodeGenAction::ExecuteAction (this=0x8297f20)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/lib/CodeGen/CodeGenAction.cpp:853
> #19 0x00000000030efc00 in clang::FrontendAction::Execute (this=0x8297f20)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/lib/Frontend/FrontendAction.cpp:457
> #20 0x0000000003094c81 in clang::CompilerInstance::ExecuteAction (this=0x827df40, Act=...)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/lib/Frontend/CompilerInstance.cpp:867
> #21 0x0000000003241ba1 in clang::ExecuteCompilerInvocation (Clang=0x827df40)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/lib/FrontendTool/ExecuteCompilerInvocation.cpp:241
> #22 0x0000000000c33bc8 in cc1_main (Argv=...,
> Argv0=0x7fffffffe3f9 "/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/tmp/clang",
> MainAddr=0xc26010 <GetExecutablePath(char const*, bool)>)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/tools/driver/cc1_main.cpp:116
> #23 0x0000000000c27c2a in ExecuteCC1Tool (argv=..., Tool=...)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/tools/driver/driver.cpp:301
> #24 0x0000000000c26ae2 in main (argc_=52, argv_=0x7fffffffdfb8)
> at /work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/tools/driver/driver.cpp:382
>
>
>
>
>
>
>
>
> ----- /tmp/main_with_3_globals-841619.c -----
>
> # 1 "<built-in>"
> # 1 "main_with_3_globals.c"
> int foo;
> char bar;
> long baz;
>
> int main(){return foo;}
>
>
>
> ----- /tmp/main_with_3_globals-841619.sh -----
>
> # Crash reproducer for clang version 3.9.0
> # Driver args: "main_with_3_globals.c" "-O3"
> # Original command: "/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/build_003/bin/clang-3.9" "-cc1" "-triple" "x86_64-unknown-linux-gnu" "-emit-obj" "-disable-free" "-main-file-name" "main_with_3_globals.c" "-mrelocation-model" "static" "-mthread-model" "posix" "-fmath-errno" "-masm-verbose" "-mconstructor-aliases" "-munwind-tables" "-fuse-init-array" "-target-cpu" "x86-64" "-momit-leaf-frame-pointer" "-dwarf-column-info" "-debugger-tuning=gdb" "-resource-dir" "/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/build_003/bin/../lib/clang/3.9.0" "-internal-isystem" "/usr/local/include" "-internal-isystem" "/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/build_003/bin/../lib/clang/3.9.0/include" "-internal-externc-isystem" "/usr/include/x86_64-linux-gnu" "-internal-externc-isystem" "/include" "-internal-externc-isystem" "/usr/include" "-O3" "-fdebug-compilation-dir" "/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/tmp" "-ferror-limit" "19" "-fmessage-length" "144" "-fobjc-runtime=gcc" "-fdiagnostics-show-option" "-fcolor-diagnostics" "-vectorize-loops" "-vectorize-slp" "-o" "/tmp/main_with_3_globals-cef92e.o" "-x" "c" "main_with_3_globals.c"
> "/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/build_003/bin/clang-3.9" "-cc1" "-triple" "x86_64-unknown-linux-gnu" "-emit-obj" "-disable-free" "-main-file-name" "main_with_3_globals.c" "-mrelocation-model" "static" "-mthread-model" "posix" "-fmath-errno" "-masm-verbose" "-mconstructor-aliases" "-munwind-tables" "-fuse-init-array" "-target-cpu" "x86-64" "-momit-leaf-frame-pointer" "-dwarf-column-info" "-debugger-tuning=gdb" "-O3" "-ferror-limit" "19" "-fmessage-length" "144" "-fobjc-runtime=gcc" "-fdiagnostics-show-option" "-fcolor-diagnostics" "-vectorize-loops" "-vectorize-slp" "-x" "c" "main_with_3_globals-841619.c"
>
>
>
>
>
>
> [the previous 3 sections, i.e. error dump + preprocessed C code + shell code: much the same with an AArch64 target, using "-target aarch64-gnu-linux" and containing the output line "Target: aarch64--linux-gnu"]
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
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