[PATCH] D64817: [CMake] Fix LLVM build non-determinism on RHEL

[Amy Kwan via Phabricator via llvm-commits]

amyk created this revision.
amyk added reviewers: nemanjai, hubert.reinterpretcast.
amyk added a project: LLVM.
Herald added subscribers: llvm-commits, mgrang, mgorny.

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.


Repository:
  rL LLVM

https://reviews.llvm.org/D64817

Files:
  llvm/cmake/modules/HandleLLVMOptions.cmake


Index: llvm/cmake/modules/HandleLLVMOptions.cmake
===================================================================
--- llvm/cmake/modules/HandleLLVMOptions.cmake
+++ llvm/cmake/modules/HandleLLVMOptions.cmake
@@ -145,6 +145,25 @@
   set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} -Wl,-flat_namespace -Wl,-undefined -Wl,suppress")
 endif()
 
+if(${CMAKE_SYSTEM_NAME} MATCHES "Linux")
+  # RHEL has ar and ranlib being non-deterministic by default. The D flag forces determinism,
+  # however only GNU version of ar and ranlib have this option
+  execute_process(COMMAND ${CMAKE_RANLIB} --version
+                  WORKING_DIRECTORY ${PROJECT_SOURCE_DIR} RESULT_VARIABLE RANLIB_RESULT OUTPUT_VARIABLE RANLIB_OUTPUT)
+  if((${RANLIB_RESULT} EQUAL 0) AND ("${RANLIB_OUTPUT}" MATCHES "GNU ranlib") AND ("${RANLIB_OUTPUT}" MATCHES "([0-9]+\\.[0-9]+)"))
+    # Version 2.23 is the first version of binutils where both ar and ranlib have the D flag
+    if("${CMAKE_MATCH_0}" VERSION_GREATER "2.22")
+      set(CMAKE_C_ARCHIVE_CREATE "<CMAKE_AR> Dqc <TARGET> <LINK_FLAGS> <OBJECTS>")
+      set(CMAKE_C_ARCHIVE_APPEND "<CMAKE_AR> Dq  <TARGET> <LINK_FLAGS> <OBJECTS>")
+      set(CMAKE_C_ARCHIVE_FINISH "<CMAKE_RANLIB> -D <TARGET>")
+  
+      set(CMAKE_CXX_ARCHIVE_CREATE "<CMAKE_AR> Dqc <TARGET> <LINK_FLAGS> <OBJECTS>")
+      set(CMAKE_CXX_ARCHIVE_APPEND "<CMAKE_AR> Dq  <TARGET> <LINK_FLAGS> <OBJECTS>")
+      set(CMAKE_CXX_ARCHIVE_FINISH "<CMAKE_RANLIB> -D <TARGET>")
+    endif()
+  endif()
+endif()
+
 if(${CMAKE_SYSTEM_NAME} MATCHES "AIX")
   if(NOT LLVM_BUILD_32_BITS)
     if (CMAKE_CXX_COMPILER_ID MATCHES "XL")


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D64817.210160.patch
Type: text/x-patch
Size: 1633 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20190716/1bef5de8/attachment.bin>