[Openmp-commits] [PATCH] D93727: [OpenMP] Add using bit flags to select Libomptarget Information

[Joseph Huber via Phabricator via Openmp-commits]

jhuber6 added inline comments.


================
Comment at: openmp/libomptarget/include/Debug.h:54-63
+static inline uint32_t getInfoLevel() {
+  static uint32_t InfoLevel = 0;
+  static std::once_flag Flag{};
+  std::call_once(Flag, []() {
+    if (char *EnvStr = getenv("LIBOMPTARGET_INFO"))
+      InfoLevel = std::stoi(EnvStr);
+  });
----------------
vzakhari wrote:
> Hello.  Am I the only one who is getting `libomptarget.rtl.x86_64.so` build fail with `-DCMAKE_BUILD_TYPE=Debug`?
> 
> > ld: CMakeFiles/omptarget.rtl.x86_64.dir/__/generic-elf-64bit/src/rtl.cpp.o: in function `getInfoLevel()::{lambda()#1}::operator()() const':
> > .../openmp/libomptarget/include/Debug.h:61: undefined reference to `getInfoLevel()::InfoLevel'
> > ld: CMakeFiles/omptarget.rtl.x86_64.dir/__/generic-elf-64bit/src/rtl.cpp.o: relocation R_X86_64_PC32 against undefined symbol `_ZZL12getInfoLevelvE9InfoLevel' can not be used when making a shared object; recompile with -fPIC
> 
> Here is a small reproducer:
> 
> ```
> #include <mutex>
> 
> static inline uint32_t getInfoLevel() {
>   static uint32_t InfoLevel = 0;
>   static std::once_flag Flag{};
>   std::call_once(Flag, []() {
>       InfoLevel = 1;
>   });
> 
>   return InfoLevel;
> }
> ```
> 
> I cannot build a shared library from it using gcc: g++ -fPIC -std=c++14 test.cpp -shared -o test.so
> 
> 
> > ld: /tmp/ccBpTXXs.o: relocation R_X86_64_PC32 against undefined symbol `_ZZL12getInfoLevelvE9InfoLevel' can not be used when making a shared object; recompile with -fPIC
> 
> 
> The issue is reproducible with GCC 5.5.0 and 6.5.0, and does not reproduce with 7.3.0.  I believe LLVM's minimal requirement is 5.1, so it is a problem.
> 
> The issue seems to be caused by the fact that getInfoLevel() is not referenced in `openmp/libomptarget/plugins/generic-elf-64bit/src/rtl.cpp`
I have no issues compiling the reproducer you provided. It compiles without errors locally and here https://godbolt.org/z/oEKq3E for the compilers you listed. There might be a problem when the compiler doesn't create a static variable when the function in unused. Does the problem go away if you create a dummy usage of getInfoLevel()?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D93727/new/

https://reviews.llvm.org/D93727