[AIX] Make sure we use export lists for plugins

Summary:
Besides just generating and consuming the lists, this includes:

 * Calling  nm with the right options in extract_symbols.py. Such as not
  demangling C++ names, which AIX nm does by default, and accepting both
  32/64-bit names.
 * Not having nm sort the list of symbols or we may run in to memory
   issues on debug builds, as nm calls a 32-bit sort.
 * Defaulting to having LLVM_EXPORT_SYMBOLS_FOR_PLUGINS on for AIX
 * CMake versions prior to 3.16 set the -brtl linker flag globally on
   AIX. Clear it out early on so we don't run into failures. We will set
   it as needed.

Reviewers: jasonliu, DiggerLin, stevewan, hubert.reinterpretcast

Reviewed By: hubert.reinterpretcast

Subscribers: hubert.reinterpretcast, mgorny, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70972

CMakeLists.txt

@@ -874,6 +874,30 @@ endif()
 if (UNIX AND ${CMAKE_SYSTEM_NAME} MATCHES "AIX")
           add_definitions("-D_XOPEN_SOURCE=700")
           add_definitions("-D_LARGE_FILE_API")
+
+  # CMake versions less than 3.16 set default linker flags to include -brtl, as
+  # well as setting -G when building libraries, so clear them out. Note we only
+  # try to clear the form that CMake will set as part of its initial
+  # configuration, it is still possible the user may force it as part of a
+  # compound option.
+  if(CMAKE_VERSION VERSION_LESS 3.16)
+    string(REGEX REPLACE "(^|[ \t]+)-Wl,-brtl([ \t]+|$)" "" 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
+      "${CMAKE_SHARED_LIBRARY_CREATE_C_FLAGS}")
+    string(REGEX REPLACE "(^|[ \t]+)(-Wl,)?-G([ \t]+|$)" "" 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
+      "${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 " -G")
+
+  # Also set the correct flags for building shared libraries.
+  string(APPEND CMAKE_SHARED_LINKER_FLAGS " -shared")
 endif()
 
 # Build with _FILE_OFFSET_BITS=64 on Solaris to match g++ >= 9.

cmake/modules/AddLLVM.cmake

@@ -90,6 +90,7 @@ function(add_llvm_symbol_exports target_name export_file)
     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")
+    set(native_export_file "${export_file}")
     set_property(TARGET ${target_name} APPEND_STRING PROPERTY
                  LINK_FLAGS " -Wl,-bE:${export_file}")
   elseif(LLVM_HAVE_LINK_VERSION_SCRIPT)
@@ -257,6 +258,11 @@ function(add_link_opts target_name)
       endif()
     endif()
   endif()
+
+  if(ARG_SUPPORT_PLUGINS AND ${CMAKE_SYSTEM_NAME} MATCHES "AIX")
+    set_property(TARGET ${target_name} APPEND_STRING PROPERTY
+                 LINK_FLAGS " -Wl,-brtl")
+  endif()
 endfunction(add_link_opts)
 
 # Set each output directory according to ${CMAKE_CONFIGURATION_TYPES}.

cmake/modules/HandleLLVMOptions.cmake

@@ -11,6 +11,7 @@ include(HandleLLVMStdlib)
 include(CheckCCompilerFlag)
 include(CheckCXXCompilerFlag)
 include(CheckSymbolExists)
+include(CMakeDependentOption)
 
 if(CMAKE_LINKER MATCHES "lld-link" OR (WIN32 AND LLVM_USE_LINKER STREQUAL "lld") OR LLVM_ENABLE_LLD)
   set(LINKER_IS_LLD_LINK TRUE)
@@ -971,12 +972,23 @@ elseif(LLVM_ENABLE_LTO)
   endif()
 endif()
 
+# Set an AIX default for LLVM_EXPORT_SYMBOLS_FOR_PLUGINS based on whether we are
+# doing dynamic linking (see below).
+set(LLVM_EXPORT_SYMBOLS_FOR_PLUGINS_AIX_default OFF)
+if (NOT (BUILD_SHARED_LIBS OR LLVM_LINK_LLVM_DYLIB))
+  set(LLVM_EXPORT_SYMBOLS_FOR_PLUGINS_AIX_default ON)
+endif()
+
 # This option makes utils/extract_symbols.py be used to determine the list of
-# symbols to export from LLVM tools. This is necessary when using MSVC if you
+# symbols to export from LLVM tools. This is necessary when on AIX or when using
-# want to allow plugins, though note that the plugin has to explicitly link
+# MSVC if you want to allow plugins. On AIX we don't show this option, and we
-# against (exactly one) tool so we can't unilaterally turn on
+# enable it by default except when the LLVM libraries are set up for dynamic
+# linking (due to incompatibility). With MSVC, note that the plugin has to
+# explicitly link against (exactly one) tool so we can't unilaterally turn on
 # LLVM_ENABLE_PLUGINS when it's enabled.
-option(LLVM_EXPORT_SYMBOLS_FOR_PLUGINS "Export symbols from LLVM tools so that plugins can import them" OFF)
+CMAKE_DEPENDENT_OPTION(LLVM_EXPORT_SYMBOLS_FOR_PLUGINS
+       "Export symbols from LLVM tools so that plugins can import them" OFF
+       "NOT ${CMAKE_SYSTEM_NAME} MATCHES AIX" ${LLVM_EXPORT_SYMBOLS_FOR_PLUGINS_AIX_default})
 if(BUILD_SHARED_LIBS AND LLVM_EXPORT_SYMBOLS_FOR_PLUGINS)
   message(FATAL_ERROR "BUILD_SHARED_LIBS not compatible with LLVM_EXPORT_SYMBOLS_FOR_PLUGINS")
 endif()

utils/extract_symbols.py

@@ -42,6 +42,11 @@ def dumpbin_get_symbols(lib):
     process.wait()
 
 def nm_get_symbols(lib):
+    if sys.platform.startswith('aix'):
+        process = subprocess.Popen(['nm','-P','-Xany','-C','-p',lib], bufsize=1,
+                                   stdout=subprocess.PIPE, stdin=subprocess.PIPE,
+                                   universal_newlines=True)
+    else:
         process = subprocess.Popen(['nm','-P',lib], bufsize=1,
                                    stdout=subprocess.PIPE, stdin=subprocess.PIPE,
                                    universal_newlines=True)