Trouble creating a unique pointer from a pointer to an existing variable - c++11

Question

I am trying to modify some parts of LLVM code. I am facing difficulty in here:
{This part of code just aims to create an OptimizationRemark which is passed on to another module}
OptimizationRemarkAnalysis &LoopAccessInfo::recordAnalysis(StringRef RemarkName,
Instruction *I) {
assert(!Report && "Multiple reports generated");
Value *CodeRegion = TheLoop->getHeader();
DebugLoc DL = TheLoop->getStartLoc();
if (I) {
CodeRegion = I->getParent();
// If there is no debug location attached to the instruction, revert back to
// using the loop's.
if (I->getDebugLoc())
DL = I->getDebugLoc();
}
OptimizationRemarkAnalysis R(DEBUG_TYPE, RemarkName, DL, CodeRegion);
Report = std::unique_ptr<OptimizationRemarkAnalysis>{&R};
return *Report;
}
When I try to build it, it works fine. But when I ran it on a benchmark, it gave errors like this:
#0 0x0000563337f8bb9f llvm::sys::PrintStackTrace(llvm::raw_ostream&) /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/lib/Support/Unix/Signals.inc:398:0
#1 0x0000563337f8bc32 PrintStackTraceSignalHandler(void*) /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/lib/Support/Unix/Signals.inc:462:0
#2 0x0000563337f89e07 llvm::sys::RunSignalHandlers() /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/lib/Support/Signals.cpp:49:0
#3 0x0000563337f8b40b SignalHandler(int) /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/lib/Support/Unix/Signals.inc:252:0
#4 0x00007f3ec0e82150 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x13150)
#5 0x0000563338f6f61a std::default_delete<llvm::OptimizationRemarkAnalysis>::operator()(llvm::OptimizationRemarkAnalysis*) const /usr/include/c++/7/bits/unique_ptr.h:78:0
#6 0x0000563338f69699 std::unique_ptr<llvm::OptimizationRemarkAnalysis, std::default_delete<llvm::OptimizationRemarkAnalysis> >::~unique_ptr() /usr/include/c++/7/bits/unique_ptr.h:269:0
#7 0x0000563338f4942c llvm::LoopAccessInfo::~LoopAccessInfo() /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/include/llvm/Analysis/LoopAccessAnalysis.h:493:0
#8 0x00005633391b9612 std::default_delete<llvm::LoopAccessInfo>::operator()(llvm::LoopAccessInfo*) const /usr/include/c++/7/bits/unique_ptr.h:78:0
#9 0x00005633391b73c1 std::unique_ptr<llvm::LoopAccessInfo, std::default_delete<llvm::LoopAccessInfo> >::~unique_ptr() /usr/include/c++/7/bits/unique_ptr.h:269:0
#10 0x00005633391b54a9 llvm::DenseMapBase<llvm::DenseMap<llvm::Loop*, std::unique_ptr<llvm::LoopAccessInfo, std::default_delete<llvm::LoopAccessInfo> >, llvm::DenseMapInfo<llvm::Loop*>, llvm::detail::DenseMapPair<llvm::Loop*, std::unique_ptr<llvm::LoopAccessInfo, std::default_delete<llvm::LoopAccessInfo> > > >, llvm::Loop*, std::unique_ptr<llvm::LoopAccessInfo, std::default_delete<llvm::LoopAccessInfo> >, llvm::DenseMapInfo<llvm::Loop*>, llvm::detail::DenseMapPair<llvm::Loop*, std::unique_ptr<llvm::LoopAccessInfo, std::default_delete<llvm::LoopAccessInfo> > > >::clear() /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/include/llvm/ADT/DenseMap.h:129:0
#11 0x00005633391b4f2a llvm::LoopAccessLegacyAnalysis::releaseMemory() /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/include/llvm/Analysis/LoopAccessAnalysis.h:702:0
#12 0x00005633377d7eda llvm::PMDataManager::freePass(llvm::Pass*, llvm::StringRef, llvm::PassDebuggingString) /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/lib/IR/LegacyPassManager.cpp:950:0
#13 0x00005633377d7dd3 llvm::PMDataManager::removeDeadPasses(llvm::Pass*, llvm::StringRef, llvm::PassDebuggingString) /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/lib/IR/LegacyPassManager.cpp:939:0
#14 0x00005633377da887 llvm::FPPassManager::runOnFunction(llvm::Function&) /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/lib/IR/LegacyPassManager.cpp:1507:0
#15 0x00005633377da935 llvm::FPPassManager::runOnModule(llvm::Module&) /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/lib/IR/LegacyPassManager.cpp:1541:0
#16 0x00005633377dacbd (anonymous namespace)::MPPassManager::runOnModule(llvm::Module&) /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/lib/IR/LegacyPassManager.cpp:1597:0
#17 0x00005633377db3e7 llvm::legacy::PassManagerImpl::run(llvm::Module&) /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/lib/IR/LegacyPassManager.cpp:1700:0
#18 0x00005633377db5df llvm::legacy::PassManager::run(llvm::Module&) /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/lib/IR/LegacyPassManager.cpp:1732:0
#19 0x000056333827078d (anonymous namespace)::EmitAssemblyHelper::EmitAssembly(clang::BackendAction, std::unique_ptr<llvm::raw_pwrite_stream, std::default_delete<llvm::raw_pwrite_stream> >) /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/tools/clang/lib/CodeGen/BackendUtil.cpp:801:0
#20 0x00005633382734c9 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_delete<llvm::raw_pwrite_stream> >) /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/tools/clang/lib/CodeGen/BackendUtil.cpp:1198:0
#21 0x0000563338e748e9 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/tools/clang/lib/CodeGen/CodeGenAction.cpp:292:0
#22 0x0000563339c2b6f8 clang::ParseAST(clang::Sema&, bool, bool) /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/tools/clang/lib/Parse/ParseAST.cpp:171:0
#23 0x0000563338936f01 clang::ASTFrontendAction::ExecuteAction() /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/tools/clang/lib/Frontend/FrontendAction.cpp:1005:0
#24 0x0000563338e72778 clang::CodeGenAction::ExecuteAction() /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/tools/clang/lib/CodeGen/CodeGenAction.cpp:1041:0
#25 0x0000563338936944 clang::FrontendAction::Execute() /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/tools/clang/lib/Frontend/FrontendAction.cpp:908:0
#26 0x00005633388d0954 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/tools/clang/lib/Frontend/CompilerInstance.cpp:992:0
#27 0x0000563338a8bf2b clang::ExecuteCompilerInvocation(clang::CompilerInstance*) /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/tools/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp:255:0
#28 0x0000563335d19fa6 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/tools/clang/tools/driver/cc1_main.cpp:221:0
#29 0x0000563335d0eced ExecuteCC1Tool(llvm::ArrayRef<char const*>, llvm::StringRef) /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/tools/clang/tools/driver/driver.cpp:309:0
#30 0x0000563335d0f9ad main /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm/tools/clang/tools/driver/driver.cpp:389:0
#31 0x00007f3ebfd8e1c1 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x211c1)
#32 0x0000563335d0c3ca _start (/home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm_build/bin/clang-7.0+0x1e223ca)
Stack dump:
0. Program arguments: /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm_build/bin/clang-7.0 -cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -disable-free -main-file-name tsc.c -mrelocation-model static -mthread-model posix -menable-no-infs -menable-no-nans -menable-unsafe-fp-math -fno-signed-zeros -mreassociate -freciprocal-math -fno-trapping-math -ffp-contract=fast -ffast-math -ffinite-math-only -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -target-feature +avx2 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer -coverage-notes-file /home/cs15btech11044/list_of_llvms/TSVC/TSVC_/tsc.gcno -resource-dir /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm_build/lib/clang/7.0.0 -internal-isystem /usr/local/include -internal-isystem /home/cs15btech11044/list_of_llvms/LLVM_second_remark/LLVM_for_commits_2/llvm_build/lib/clang/7.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O3 -Rpass-analysis=loop-vectorize -Rpass=loop-vectorize -fdebug-compilation-dir /home/cs15btech11044/list_of_llvms/TSVC/TSVC_ -ferror-limit 19 -fmessage-length 150 -fobjc-runtime=gcc -fdiagnostics-show-option -fcolor-diagnostics -vectorize-loops -vectorize-slp -o tsc.ll -x c tsc.c
1. <eof> parser at end of file
2. Per-module optimization passes
3. Running pass 'Function Pass Manager' on module 'tsc.c'.
4. Releasing pass 'Loop Access Analysis'
clang-7.0: error: unable to execute command: Segmentation fault (core dumped)
clang-7.0: error: clang frontend command failed due to signal (use -v to see invocation)
clang version 7.0.0 (https://git.llvm.org/git/clang.git/ d925bc6affe1ed96737cc016f0dc53cdd89bee5b) (https://git.llvm.org/git/llvm.git/ 1cb64026709ddf4b7cbb090faef8457968df581a)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/cs15btech11044/list_of_llvms/TSVC/TSVC_/../../LLVM_second_remark/LLVM_for_commits_2/llvm_build/bin
clang-7.0: note: diagnostic msg: PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace, preprocessed source, and associated run script.
clang-7.0: note: diagnostic msg:
********************
PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang-7.0: note: diagnostic msg: /tmp/tsc-c03557.c
clang-7.0: note: diagnostic msg: /tmp/dummy-ddbe6a.c
clang-7.0: note: diagnostic msg: /tmp/tsc-c03557.sh
clang-7.0: note: diagnostic msg:
********************
Mainly the issue is arising due to these lines,
OptimizationRemarkAnalysis R(DEBUG_TYPE, RemarkName, DL, CodeRegion);
Report = std::unique_ptr<OptimizationRemarkAnalysis>{&R};
I would like to know why is this not possible and whether is there any other way to convert any pointer to a unique pointer in C++11.

Answer 1

This fails because R goes out of scope, and it's on the stack anyway - so you can't have a unique pointer to its address without it becomes invalid. Try this instead:
auto Report = std::unique_ptr<OptimizationRemarkAnalysis>{
new OptimizationRemarkAnalysis(DEBUG_TYPE, RemarkName, DL, CodeRegion) };
or in C++14:
auto Report = std::make_unique<OptimizationRemarkAnalysis>(
DEBUG_TYPE, RemarkName, DL, CodeRegion);