[PATCH] D90041: [AIX][cmake] Adjust management of `-G` for linking

[Hubert Tong via Phabricator via llvm-commits]

hubert.reinterpretcast created this revision.
hubert.reinterpretcast added reviewers: daltenty, Xiangling_L, amyk, stevewan.
Herald added a subscriber: mgorny.
Herald added a project: LLVM.
hubert.reinterpretcast requested review of this revision.

The change in 0ba98433971f <https://reviews.llvm.org/rG0ba98433971f6aa7cf4dc2befe7b5446d25d5956> changed the behaviour of the build when using an XL build compiler because `-G` is not a pure linker option: it also implies `-shared`. This was accounted for in the base CMake configuration, so an analysis of the change from 0ba98433971f <https://reviews.llvm.org/rG0ba98433971f6aa7cf4dc2befe7b5446d25d5956> in relation to a build using Clang (where `-shared` is introduced by CMake) would not identify the issue. This patch resolves this particular issue by adding `-shared` alongside `-Wl,-G`.

At the same time, the investigation reveals that several aspects of the various build configurations are not operating in the manner originally intended.

The other issue related to the `-G` linker option in the build is that the removal of it (to avoid unnecessary use of run-time linking) is not effective for the build using the Clang compiler. This patch addresses this by adjusting the regular expressions used to remove the broadly-applied `-G`.

Finally, the issue of specifying the export list with `-Wl,` instead of a compiler option is flagged with a FIXME comment.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D90041

Files:
  llvm/CMakeLists.txt
  llvm/cmake/modules/AddLLVM.cmake


Index: llvm/cmake/modules/AddLLVM.cmake
===================================================================
--- llvm/cmake/modules/AddLLVM.cmake
+++ llvm/cmake/modules/AddLLVM.cmake
@@ -90,6 +90,8 @@
     set_property(TARGET ${target_name} APPEND_STRING PROPERTY
                  LINK_FLAGS " -Wl,-exported_symbols_list,\"${CMAKE_CURRENT_BINARY_DIR}/${native_export_file}\"")
   elseif(${CMAKE_SYSTEM_NAME} MATCHES "AIX")
+    # FIXME: `-Wl,-bE:` bypasses whatever handling there is in the build
+    # compiler driver to defer to the specified export list.
     set(native_export_file "${export_file}")
     set_property(TARGET ${target_name} APPEND_STRING PROPERTY
                  LINK_FLAGS " -Wl,-bE:${export_file}")
Index: llvm/CMakeLists.txt
===================================================================
--- llvm/CMakeLists.txt
+++ llvm/CMakeLists.txt
@@ -917,20 +917,26 @@
   # configuration, it is still possible the user may force it as part of a
   # compound option.
   if(CMAKE_VERSION VERSION_LESS 3.16)
-    string(REGEX REPLACE "(^|[ \t]+)-Wl,-brtl([ \t]+|$)" "" CMAKE_EXE_LINKER_FLAGS  "${CMAKE_EXE_LINKER_FLAGS}")
-    string(REGEX REPLACE "(^|[ \t]+)-Wl,-brtl([ \t]+|$)" "" CMAKE_SHARED_LINKER_FLAGS  "${CMAKE_SHARED_LINKER_FLAGS}")
-    string(REGEX REPLACE "(^|[ \t]+)-Wl,-brtl([ \t]+|$)" "" CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS}")
-    string(REGEX REPLACE "(^|[ \t]+)(-Wl,)?-G([ \t]+|$)" "" CMAKE_SHARED_LIBRARY_CREATE_C_FLAGS
+    string(REGEX REPLACE "(^|[ \t]+)-Wl,-brtl([ \t]+|$)" " " CMAKE_EXE_LINKER_FLAGS  "${CMAKE_EXE_LINKER_FLAGS}")
+    string(REGEX REPLACE "(^|[ \t]+)-Wl,-brtl([ \t]+|$)" " " CMAKE_SHARED_LINKER_FLAGS  "${CMAKE_SHARED_LINKER_FLAGS}")
+    string(REGEX REPLACE "(^|[ \t]+)-Wl,-brtl([ \t]+|$)" " " CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS}")
+    string(REGEX REPLACE "(^|[ \t]+)(-Wl,)?-G([ \t]+|$)" " " CMAKE_SHARED_LIBRARY_CREATE_C_FLAGS
       "${CMAKE_SHARED_LIBRARY_CREATE_C_FLAGS}")
-    string(REGEX REPLACE "(^|[ \t]+)(-Wl,)?-G([ \t]+|$)" "" CMAKE_SHARED_LIBRARY_CREATE_CXX_FLAGS
+    string(REGEX REPLACE "(^|[ \t]+)(-Wl,)?-G([ \t]+|$)" " " CMAKE_SHARED_LIBRARY_CREATE_CXX_FLAGS
       "${CMAKE_SHARED_LIBRARY_CREATE_CXX_FLAGS}")
-    string(REGEX REPLACE "(^|[ \t]+)(-Wl,)?-G([ \t]+|$)" "" CMAKE_SHARED_LIBRARY_CREATE_ASM_FLAGS
+    string(REGEX REPLACE "(^|[ \t]+)(-Wl,)?-G([ \t]+|$)" " " CMAKE_SHARED_LIBRARY_CREATE_ASM_FLAGS
+      "${CMAKE_SHARED_LIBRARY_CREATE_ASM_FLAGS}")
+    string(REGEX REPLACE "(^|[ \t]+)-Wl,-G," " -Wl," CMAKE_SHARED_LIBRARY_CREATE_C_FLAGS
+      "${CMAKE_SHARED_LIBRARY_CREATE_C_FLAGS}")
+    string(REGEX REPLACE "(^|[ \t]+)-Wl,-G," " -Wl," CMAKE_SHARED_LIBRARY_CREATE_CXX_FLAGS
+      "${CMAKE_SHARED_LIBRARY_CREATE_CXX_FLAGS}")
+    string(REGEX REPLACE "(^|[ \t]+)-Wl,-G," " -Wl," CMAKE_SHARED_LIBRARY_CREATE_ASM_FLAGS
       "${CMAKE_SHARED_LIBRARY_CREATE_ASM_FLAGS}")
   endif()
 
-  # Modules should be built with -G, so we can use runtime linking with
-  # plugins.
-  string(APPEND CMAKE_MODULE_LINKER_FLAGS " -Wl,-G")
+  # Modules should be built with -shared -Wl,-G, so we can use runtime linking
+  # with plugins.
+  string(APPEND CMAKE_MODULE_LINKER_FLAGS " -shared -Wl,-G")
 
   # Also set the correct flags for building shared libraries.
   string(APPEND CMAKE_SHARED_LINKER_FLAGS " -shared")


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