From 3fb3157dae5427b6c86949ec1603986c57602658 Mon Sep 17 00:00:00 2001 From: Brad King Date: Wed, 17 Jul 2019 09:20:31 -0400 Subject: AIX: Do not enable runtime linking by default anymore We've long created shared objects on AIX using the linker's `-G` option (also offered by the XL front-end). The `-G` option implies `-brtl` and enables runtime linking. This has been largely unnecessary because we provide all dependencies on the link line and both XL and GNU compilers offer builtin behavior to export symbols. Since commit 0f150b69d3 (AIX: Explicitly compute shared object exports for both XL and GNU, 2019-07-11) we compute exports explicitly and consistently. Therefore runtime linking is no longer necessary for shared objects. We've also long created executables on AIX using the linker's `-brtl` option to enable runtime linking in case they load plugins at runtime. Since commit 9f5c2040bf (AIX: Explicitly compute executable exports for both XL and GNU, 2019-07-12) and commit 2fa920c0cd (AIX: Create import library for executables with exports, 2019-07-16) we now provide the linker enough information to fully resolve symbols in plugins up front. Therefore runtime linking is no longer necessary for executables. Drop use of `-G` for creating shared objects and use the XL `-qmkshrobj` and GCC `-shared` options instead. Both invoke the linker with the `-bM:SRE -bnoentry` options to create a shared object without runtime linking enabled. Also drop use of `-brtl` for creating executables. Issue: #19163 --- Help/release/dev/aix.rst | 10 ++++++++++ Modules/Platform/AIX-GNU.cmake | 8 +------- Modules/Platform/AIX-XL.cmake | 8 +------- 3 files changed, 12 insertions(+), 14 deletions(-) diff --git a/Help/release/dev/aix.rst b/Help/release/dev/aix.rst index c24872e..6919358 100644 --- a/Help/release/dev/aix.rst +++ b/Help/release/dev/aix.rst @@ -8,3 +8,13 @@ aix to the executable for its symbols are now linked using the import file. The :command:`install(TARGETS)` command now installs the import file as an ``ARCHIVE`` artifact. + +* On AIX, runtime linking is no longer enabled by default. CMake provides + the linker enough information to resolve all symbols up front. + One may manually enable runtime linking for shared libraries and/or + loadable modules by adding ``-Wl,-G`` to their link flags + (e.g. in the :variable:`CMAKE_SHARED_LINKER_FLAGS` or + :variable:`CMAKE_MODULE_LINKER_FLAGS` variable). + One may manually enable runtime linking for executables by adding + ``-Wl,-brtl`` to their link flags (e.g. in the + :variable:`CMAKE_EXE_LINKER_FLAGS` variable). diff --git a/Modules/Platform/AIX-GNU.cmake b/Modules/Platform/AIX-GNU.cmake index 9e981c6..61d213a 100644 --- a/Modules/Platform/AIX-GNU.cmake +++ b/Modules/Platform/AIX-GNU.cmake @@ -8,16 +8,10 @@ if(__AIX_COMPILER_GNU) endif() set(__AIX_COMPILER_GNU 1) -# -# By default, runtime linking is enabled. All shared objects specified on the command line -# will be listed, even if there are no symbols referenced, in the output file. -string(APPEND CMAKE_EXE_LINKER_FLAGS_INIT " -Wl,-brtl") - - macro(__aix_compiler_gnu lang) set(CMAKE_SHARED_LIBRARY_RUNTIME_${lang}_FLAG "-Wl,-blibpath:") set(CMAKE_SHARED_LIBRARY_RUNTIME_${lang}_FLAG_SEP ":") - string(APPEND CMAKE_SHARED_LIBRARY_CREATE_${lang}_FLAGS " -Wl,-G,-bnoipath") + string(APPEND CMAKE_SHARED_LIBRARY_CREATE_${lang}_FLAGS " -Wl,-bnoipath") set(CMAKE_SHARED_LIBRARY_LINK_${lang}_FLAGS "-Wl,-bexpall") # CMP0065 old behavior set(CMAKE_${lang}_USE_IMPLICIT_LINK_DIRECTORIES_IN_RUNTIME_PATH 1) diff --git a/Modules/Platform/AIX-XL.cmake b/Modules/Platform/AIX-XL.cmake index 3424e2c..64b0bc1 100644 --- a/Modules/Platform/AIX-XL.cmake +++ b/Modules/Platform/AIX-XL.cmake @@ -8,16 +8,10 @@ if(__AIX_COMPILER_XL) endif() set(__AIX_COMPILER_XL 1) -# -# By default, runtime linking is enabled. All shared objects specified on the command line -# will be listed, even if there are no symbols referenced, in the output file. -string(APPEND CMAKE_EXE_LINKER_FLAGS_INIT " -Wl,-brtl") - - macro(__aix_compiler_xl lang) set(CMAKE_SHARED_LIBRARY_RUNTIME_${lang}_FLAG "-Wl,-blibpath:") set(CMAKE_SHARED_LIBRARY_RUNTIME_${lang}_FLAG_SEP ":") - set(CMAKE_SHARED_LIBRARY_CREATE_${lang}_FLAGS "-G -Wl,-bnoipath") # -shared + string(APPEND CMAKE_SHARED_LIBRARY_CREATE_${lang}_FLAGS " -Wl,-bnoipath") set(CMAKE_SHARED_LIBRARY_LINK_${lang}_FLAGS "-Wl,-bexpall") # CMP0065 old behavior set(CMAKE_SHARED_LIBRARY_${lang}_FLAGS " ") set(CMAKE_SHARED_MODULE_${lang}_FLAGS " ") -- cgit v0.12