Commit c84c62c5 authored by Amy Kwan's avatar Amy Kwan
Browse files

[CMake] Fix LLVM build non-determinism on RHEL 

On RHEL, the OS tooling (ar, ranlib) is not deterministic by default.
Therefore, we cannot get bit-for-bit identical builds.

The goal of this patch is that it adds the flags required to force determinism.

Differential Revision: https://reviews.llvm.org/D64817
parent 29f6f9b2

llvm/cmake/modules/HandleLLVMOptions.cmake

+22 −0
Original line number Diff line number Diff line
@@ -135,6 +135,28 @@ if(APPLE) 
  set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} -Wl,-flat_namespace -Wl,-undefined -Wl,suppress")

endif()



if(${CMAKE_SYSTEM_NAME} MATCHES "Linux")

  # RHEL7 has ar and ranlib being non-deterministic by default. The D flag forces determinism,

  # however only GNU version of ar and ranlib (2.27) have this option. 

  # RHEL DTS7 is also affected by this, which uses GNU binutils 2.28

  execute_process(COMMAND ${CMAKE_AR} rD t.a

                  WORKING_DIRECTORY ${CMAKE_BINARY_DIR} RESULT_VARIABLE AR_RESULT OUTPUT_VARIABLE RANLIB_OUTPUT)

  if(${AR_RESULT} EQUAL 0)

    execute_process(COMMAND ${CMAKE_RANLIB} -D t.a

                    WORKING_DIRECTORY ${CMAKE_BINARY_DIR} RESULT_VARIABLE RANLIB_RESULT OUTPUT_VARIABLE RANLIB_OUTPUT)

    if(${RANLIB_RESULT} EQUAL 0)

      set(CMAKE_C_ARCHIVE_CREATE "<CMAKE_AR> Dqc <TARGET> <LINK_FLAGS> <OBJECTS>")

      set(CMAKE_C_ARCHIVE_APPEND "<CMAKE_AR> Dq  <TARGET> <LINK_FLAGS> <OBJECTS>")

      set(CMAKE_C_ARCHIVE_FINISH "<CMAKE_RANLIB> -D <TARGET>")



      set(CMAKE_CXX_ARCHIVE_CREATE "<CMAKE_AR> Dqc <TARGET> <LINK_FLAGS> <OBJECTS>")

      set(CMAKE_CXX_ARCHIVE_APPEND "<CMAKE_AR> Dq  <TARGET> <LINK_FLAGS> <OBJECTS>")

      set(CMAKE_CXX_ARCHIVE_FINISH "<CMAKE_RANLIB> -D <TARGET>")

    endif()

    file(REMOVE ${CMAKE_BINARY_DIR}/t.a)

  endif()

endif()



if(${CMAKE_SYSTEM_NAME} MATCHES "AIX")

  if(NOT LLVM_BUILD_32_BITS)

    if (CMAKE_CXX_COMPILER_ID MATCHES "XL")