[tools][remarks-shlib] Don't build libRemarks.so without PIC

[ro]

Summary

A build on sparcv9-sun-solaris2.11 with -DLLVM_ENABLE_PIC=Off failed linking libRemarks.so:

[27/2297] Linking CXX shared library lib/libRemarks.so.12git
FAILED: lib/libRemarks.so.12git
[...]
ld: fatal: relocation error: R_SPARC_H44: file lib/libLLVMRemarks.a(Remark.cpp.o): symbol _ZTVN4llvm18raw_string_ostreamE: invalid shared object relocation type: ABS44 code model unsupported
[...]

On Solaris/sparcv9 as on many other targets you cannot link non-PIC objects into a shared object.

The following patch avoids this by not building the library with PIC. It allowed the build to complete and ninja check-all showed no errors.

[thegameg]

Can you wrap the condition around the whole file? The rest is not useful without the library anyway.

[ro]

Wrap whole file in if(LLVM_ENABLE_PIC).

Tested on amd64-pc-solaris2.11 with and without -DLLVM_ENABLE_PIC=Off.

[lebedev.ri]

llvm/tools/remarks-shlib/CMakeLists.txt

1–2

Is this the only LLVM shared library that was missing this if(LLVM_ENABLE_PIC) check?
If not, this comment is misleading, since clearly it worked so far everywhere else.

[ro]

llvm/tools/remarks-shlib/CMakeLists.txt

1–2

No, LLVMPolly.so had the same issue: fixed in D85627.

[thegameg]

LGTM

llvm/tools/remarks-shlib/CMakeLists.txt

1–2

Possibly libLTO.so too? But maybe it doesn't get built during check-all on your platform. There is LLVM_TOOL_LTO_BUILD but from what I see it's never checked.

[ro]

llvm/tools/remarks-shlib/CMakeLists.txt

1–2

I do find libLTO.so in a default (i.e. PIC) build on Solaris, but it's omitted with -DLLVM_ENABLE_PIC=Off without doing anything special.

llvm/tools/remarks-shlib/CMakeLists.txt

+# Building shared libraries requires PIC objects.
+if(LLVM_ENABLE_PIC)
+
   set(LLVM_LINK_COMPONENTS
     Remarks
     )
 
   set(SOURCES
     libremarks.cpp
     )
 
   set(LLVM_EXPORTED_SYMBOL_FILE ${CMAKE_CURRENT_SOURCE_DIR}/Remarks.exports)
 
   add_llvm_library(Remarks SHARED INSTALL_WITH_TOOLCHAIN ${SOURCES})
 
   if (LLVM_INTEGRATED_CRT_ALLOC AND MSVC)
     # Make sure we search LLVMSupport first, before the CRT libs
     set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -INCLUDE:malloc")
   endif()
   
   install(FILES ${LLVM_MAIN_INCLUDE_DIR}/llvm-c/Remarks.h
     DESTINATION include/llvm-c
     COMPONENT Remarks)
 
   if (APPLE)
     set(REMARKS_VERSION ${LLVM_VERSION_MAJOR})
     set_property(TARGET Remarks APPEND_STRING PROPERTY
                  LINK_FLAGS
                  " -compatibility_version 1 -current_version ${REMARKS_VERSION}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH}")
   endif()
+
+endif()