Build failure when targeting LLVM 11.0

[kcgen]

MacOS has moved to Clang 11, and for create_llvm_prof to target it we need to build autofdo --with-llvm=$(which llvm-config-11). The configuration phase passes, but building the create_llvm_prof binary fail both with gcc-9.x and clang-11 due to a missing operator[] in llvm_profile_writer.cc.

When building with GCC-9:

g++-9 -DHAVE_CONFIG_H -I. -I./glog/src  -I. -I./glog/src -I./third_party/perf_data_converter/src/quipper -I./third_party/protobuf/src  -I/usr/lib/llvm-11/include -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -DCREATE_LLVM_PROF -g -O2 -MT create_llvm_prof-llvm_profile_writer.o -MD -MP -MF .deps/create_llvm_prof-llvm_profile_writer.Tpo -c -o create_llvm_prof-llvm_profile_writer.o `test -f 'llvm_profile_writer.cc' || echo './'`llvm_profile_writer.cc
llvm_profile_writer.cc: In member function ‘virtual void autofdo::LLVMProfileBuilder::VisitCallsite(const Callsite&)’:
llvm_profile_writer.cc:100:32: error: no match for ‘operator[]’ (operand types are ‘llvm::sampleprof::FunctionSamplesMap’ {aka ‘std::map<std::__cxx11::basic_string<char>, llvm::sampleprof::FunctionSamples, std::less<void> >’} and ‘llvm::StringRef’)
  100 |           line, discriminator))[CalleeName];
      |                                ^
In file included from /usr/include/c++/9/map:61,
                 from llvm_profile_writer.cc:22:
/usr/include/c++/9/bits/stl_map.h:490:7: note: candidate: ‘std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](const key_type&) [with _Key = std::__cxx11::basic_string<char>; _Tp = llvm::sampleprof::FunctionSamples; _Compare = std::less<void>; _Alloc = std::allocator<std::pair<const std::__cxx11::basic_string<char>, llvm::sampleprof::FunctionSamples> >; std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type = llvm::sampleprof::FunctionSamples; std::map<_Key, _Tp, _Compare, _Alloc>::key_type = std::__cxx11::basic_string<char>]’
  490 |       operator[](const key_type& __k)
      |       ^~~~~~~~
/usr/include/c++/9/bits/stl_map.h:490:34: note:   no known conversion for argument 1 from ‘llvm::StringRef’ to ‘const key_type&’ {aka ‘const std::__cxx11::basic_string<char>&’}
  490 |       operator[](const key_type& __k)
      |                  ~~~~~~~~~~~~~~~~^~~
/usr/include/c++/9/bits/stl_map.h:510:7: note: candidate: ‘std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](std::map<_Key, _Tp, _Compare, _Alloc>::key_type&&) [with _Key = std::__cxx11::basic_string<char>; _Tp = llvm::sampleprof::FunctionSamples; _Compare = std::less<void>; _Alloc = std::allocator<std::pair<const std::__cxx11::basic_string<char>, llvm::sampleprof::FunctionSamples> >; std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type = llvm::sampleprof::FunctionSamples; std::map<_Key, _Tp, _Compare, _Alloc>::key_type = std::__cxx11::basic_string<char>]’
  510 |       operator[](key_type&& __k)
      |       ^~~~~~~~
/usr/include/c++/9/bits/stl_map.h:510:29: note:   no known conversion for argument 1 from ‘llvm::StringRef’ to ‘std::map<std::__cxx11::basic_string<char>, llvm::sampleprof::FunctionSamples, std::less<void> >::key_type&&’ {aka ‘std::__cxx11::basic_string<char>&&’}
  510 |       operator[](key_type&& __k)
      |                  ~~~~~~~~~~~^~~
make[1]: *** [Makefile:1234: create_llvm_prof-llvm_profile_writer.o] Error 1

When building with Clang-11:

clang++-11 -DHAVE_CONFIG_H -I. -I./glog/src  -I. -I./glog/src -I./third_party/perf_data_converter/src/quipper -I./third_party/protobuf/src  -I/usr/lib/llvm-11/include -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -DCREATE_LLVM_PROF -g -O2 -MT create_llvm_prof-llvm_profile_writer.o -MD -MP -MF .deps/create_llvm_prof-llvm_profile_writer.Tpo -c -o create_llvm_prof-llvm_profile_writer.o `test -f 'llvm_profile_writer.cc' || echo './'`llvm_profile_writer.cc
In file included from llvm_profile_writer.cc:30:
In file included from ./llvm_profile_writer.h:7:
./profile_writer.h:186:8: warning: 'VisitCallsite' overrides a member function but is not marked 'override' [-Winconsistent-missing-override]
  void VisitCallsite(const Callsite &callsite) {
       ^
./profile_writer.h:152:16: note: overridden virtual function is here
  virtual void VisitCallsite(const Callsite &offset) {}
               ^
llvm_profile_writer.cc:100:32: error: no viable overloaded operator[] for type 'llvm::sampleprof::FunctionSamplesMap' (aka 'map<basic_string<char>, llvm::sampleprof::FunctionSamples, less<> >')
          line, discriminator))[CalleeName];
          ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~
/usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/stl_map.h:490:7: note: candidate function not viable: no known conversion from 'llvm::StringRef' to 'const std::map<std::__cxx11::basic_string<char>, llvm::sampleprof::FunctionSamples, std::less<void>, std::allocator<std::pair<const std::__cxx11::basic_string<char>, llvm::sampleprof::FunctionSamples> > >::key_type' (aka 'const std::__cxx11::basic_string<char>') for 1st argument
      operator[](const key_type& __k)
      ^
/usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/stl_map.h:510:7: note: candidate function not viable: no known conversion from 'llvm::StringRef' to 'std::map<std::__cxx11::basic_string<char>, llvm::sampleprof::FunctionSamples, std::less<void>, std::allocator<std::pair<const std::__cxx11::basic_string<char>, llvm::sampleprof::FunctionSamples> > >::key_type' (aka 'std::__cxx11::basic_string<char>') for 1st argument
      operator[](key_type&& __k)
      ^
1 warning and 1 error generated.

[ruijiefang]

Can verify this is an issue for LLVM 11. Are there any plans for fixes?

---

I think the main issue is not really the absence of overloaded [] which the map provides, but casting from a StringRef to a C++ basic_string<char> --- which might have been broken because of LLVM11-induced changes to the llvm::StringRef class?

[ruijiefang]

Please see #90; I have created a pull request. I verified it works when compiling with LLVM11. In the meanwhile, a working version rests at https://github.com/ruijiefang/autofdo.

[nickdesaulniers]

I see this as well.