[flang] Fixing shared library builds

[Renaud-K]

Builds with BUILD_SHARED_LIBS=On are broken in fir-dev.
Re-enabling them by updating new library dependencies and separating the Fortran main from the runtime.

I could not find a way with cmake to make Fortran_main.c just compile and export Fortran_main.o
add_llvm_library( libname OBJECT ...) does not work. After half a day of painful experiments I decided to make a static Fortran_main.a

[jeanPerier]

Thanks for having identified the issue and proposing a fix. I tried building your PR with both BUILD_SHARED_LIBS On and Off in my environment of the day (gcc 8.3 on linux, nothing very special in the cmake command) . Both builds failed for different reasons. I identified the issues and was able to fix them (see inlined comment).

Here is the code I had to change if it can help: 12ee61e

Also, I think we may want to centralize all end-to-end tests in their own folder to better control how we deal with them.

My cmake command line:

-DCMAKE_CXX_STANDARD=17 -DLLVM_BUILD_TOOLS=On -DLLVM_TARGETS_TO_BUILD=X86 -DLLVM_INSTALL_UTILS=On  -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIBS=Off -DLLVM_ENABLE_PROJECTS="mlir;flang" -DCMAKE_CXX_FLAGS="" -DCMAKE_EXE_LINKER_FLAGS="" -DCMAKE_SHARED_LINKER_FLAGS=""

[schweitzpgi]

Also, I think we may want to centralize all end-to-end tests in their own folder to better control how we deal with them.

We do. #672

[jeanPerier]

I can now compile this patch with both BUILD_SHARED_LIBS On and Off, thanks !

[schweitzpgi]

I can now compile this patch with both BUILD_SHARED_LIBS On and Off, thanks !

Has @tskeith tried it on the Mac?

[tskeith]

I can now compile this patch with both BUILD_SHARED_LIBS On and Off, thanks !

Has @tskeith tried it on the Mac?

I just tried and got this error building lib/libFortranEvaluate.dylib:

Undefined symbols for architecture x86_64:
  "Fortran::semantics::operator<<(llvm::raw_ostream&, Fortran::semantics::Symbol const&)", referenced from:
      Fortran::semantics::Symbol::dump() const in call.cpp.o
      Fortran::semantics::Symbol::dump() const in characteristics.cpp.o
      Fortran::semantics::Symbol::dump() const in check-expression.cpp.o
      Fortran::semantics::Symbol::dump() const in constant.cpp.o
      Fortran::semantics::Symbol::dump() const in expression.cpp.o
      Fortran::semantics::Symbol::dump() const in fold.cpp.o
      Fortran::semantics::Symbol::dump() const in fold-character.cpp.o
      ...

[Renaud-K]

It rmeans that more dependencies need to be fixed. But I don't have OS X machine to run on.

[schweitzpgi]

I can now compile this patch with both BUILD_SHARED_LIBS On and Off, thanks !

Has @tskeith tried it on the Mac?

I just tried and got this error building lib/libFortranEvaluate.dylib:

Undefined symbols for architecture x86_64:
  "Fortran::semantics::operator<<(llvm::raw_ostream&, Fortran::semantics::Symbol const&)", referenced from:
      Fortran::semantics::Symbol::dump() const in call.cpp.o
      Fortran::semantics::Symbol::dump() const in characteristics.cpp.o
      Fortran::semantics::Symbol::dump() const in check-expression.cpp.o
      Fortran::semantics::Symbol::dump() const in constant.cpp.o
      Fortran::semantics::Symbol::dump() const in expression.cpp.o
      Fortran::semantics::Symbol::dump() const in fold.cpp.o
      Fortran::semantics::Symbol::dump() const in fold-character.cpp.o
      ...

[NFC] ifdef'd this so Symbol::dump() (which is the LLVM regular debug interface) is only in Debug builds now.

[schweitzpgi]

This broke testing.

Failed Tests (3):
  Flang :: Examples/hello.f90
  Flang :: Lower/associate-construct.f90
  Flang :: Lower/end-to-end-always-exec-loopbody.f90