[SystemZ/ZOS] Additions to the build system.

[Kai]

Summary

This change extend the CMake files with the necessary additions to build for z/OS.

[hubert.reinterpretcast]

llvm/CMakeLists.txt

402

Is it actually true that the resulting code is not position-independent? I thought that all XPLINK code is DLL-enabled. The outcome where the resulting code is position-independent (without the need to specify additional options) should be expressed differently from what is done here.

llvm/cmake/modules/AddLLVM.cmake

252

The various "strip" binder options are not the default, so there is a TODO here to enable the removal of the unneeded portions of the input to the linking process (which should help in terms of binary size).

llvm/cmake/modules/GetHostTriple.cmake

17–19

I think CMAKE_SYSTEM_NAME (used above for z/OS) is right: The "host" of the resulting build is the target of this CMake build. @daltenty, if you agree, I think a small patch would make sense (likely to create a merge conflict with this one though)...

llvm/cmake/modules/HandleLLVMOptions.cmake

1040

What is the nature of this limitation? "Not supported" messages tend to confuse, because someone wanting to solve the issue (other than not using whatever is "unsupported") needs some rationale in order to make progress.

Indeed, the text of the message speaks to a limitation to the implementation strategy used by the build and does not directly say much about there being a limitation in achieving the outcome that the option is intended to produce.

[daltenty]

llvm/cmake/modules/GetHostTriple.cmake

17–19

I agree that is probably more desirable in the long run, though it does create a behavior difference between platforms which rely on "config.guess" (which won't respect the CMAKE_SYSTEM_NAME and will always use the host) and those that don't (i.e. AIX / z/OS).

[Kai]

llvm/CMakeLists.txt

402

You're right. This is not required.

llvm/cmake/modules/HandleLLVMOptions.cmake

1040

I agree that this is text is unclear. I'll deal later with this.

[Kai]

• Position-independent code needs not to be disabled
• Removed message stating that static symbol export is not supported

[hubert.reinterpretcast]

llvm/cmake/modules/AddLLVM.cmake

252

@Kai, can we at least add a TODO comment to set up linker garbage collection for a z/OS toolchain?

llvm/cmake/modules/GetHostTriple.cmake

17–19

@Kai, are you okay with making a drive-by fix for AIX in this patch to keep the usage consistent?

[Kai]

llvm/cmake/modules/AddLLVM.cmake

252

For sure.

llvm/cmake/modules/GetHostTriple.cmake

17–19

Yes, no problem. What should I add?

[hubert.reinterpretcast]

llvm/cmake/modules/GetHostTriple.cmake

17–19

Yes, no problem. What should I add?

[hubert.reinterpretcast]

llvm/cmake/modules/GetHostTriple.cmake

17–19

I am suggesting that we use CMAKE_SYSTEM_NAME for both the AIX and z/OS queries (i.e., we should be consistent between the two here). The CMAKE_HOST_SYSTEM_NAME does not always reflect the host system for a build using the compiler resulting from the current build.

@daltenty pointed out that there is a logic error for some other platforms (and that using CMAKE_HOST_SYSTEM_NAME is consistent with that logic error). I do not believe that adopting the logic error for AIX and z/OS is necessarily better.

[Kai]

• Added a TODO comment to the linker strip section
• Both z/OS and AIX now use CMAKE_SYSTEM_NAME to determine the host system

[hubert.reinterpretcast]

LGTM; thanks.

llvm/CMakeLists.txt

 option(LLVM_ENABLE_TERMINFO "Use terminfo database if available." ON)
 
 set(LLVM_ENABLE_LIBXML2 "ON" CACHE STRING "Use libxml2 if available. Can be ON, OFF, or FORCE_ON")
 
 option(LLVM_ENABLE_LIBEDIT "Use libedit if available." ON)
 
 option(LLVM_ENABLE_LIBPFM "Use libpfm for performance counters if available." ON)
 
+# On z/OS, threads cannot be used because TLS is not supported.
+if (CMAKE_SYSTEM_NAME MATCHES "OS390")
+  option(LLVM_ENABLE_THREADS "Use threads if available." OFF)
+else()
   option(LLVM_ENABLE_THREADS "Use threads if available." ON)
+endif()
 
 set(LLVM_ENABLE_ZLIB "ON" CACHE STRING "Use zlib for compression/decompression if available. Can be ON, OFF, or FORCE_ON")
 
 set(LLVM_Z3_INSTALL_DIR "" CACHE STRING "Install directory of the Z3 solver.")
 
 option(LLVM_ENABLE_Z3_SOLVER
   "Enable Support for the Z3 constraint solver in LLVM."
   ${LLVM_ENABLE_Z3_SOLVER_DEFAULT}

 endif()
 
 set(LLVM_TARGETS_TO_BUILD
    ${LLVM_TARGETS_TO_BUILD}
    ${LLVM_EXPERIMENTAL_TARGETS_TO_BUILD})
 list(REMOVE_DUPLICATES LLVM_TARGETS_TO_BUILD)
 
 option(LLVM_ENABLE_PIC "Build Position-Independent Code" ON)
 option(LLVM_ENABLE_WARNINGS "Enable compiler warnings." ON)
 option(LLVM_ENABLE_MODULES "Compile with C++ modules enabled." OFF)
 if(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
   option(LLVM_ENABLE_MODULE_DEBUGGING "Compile with -gmodules." ON)
 else()
   option(LLVM_ENABLE_MODULE_DEBUGGING "Compile with -gmodules." OFF)
 endif()
 option(LLVM_ENABLE_LOCAL_SUBMODULE_VISIBILITY "Compile with -fmodules-local-submodule-visibility." ON)
 option(LLVM_ENABLE_LIBCXX "Use libc++ if available." OFF)
if (UNIX AND ${CMAKE_SYSTEM_NAME} MATCHES "AIX")
   # 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 _XOPEN_SOURCE on z/OS.
+if (CMAKE_SYSTEM_NAME MATCHES "OS390")
+  add_definitions("-D_XOPEN_SOURCE=600")
+  add_definitions("-D_OPEN_SYS") # Needed for process information.
+  add_definitions("-D_OPEN_SYS_FILE_EXT") # Needed for EBCDIC I/O.
+endif()
+
 # Build with _FILE_OFFSET_BITS=64 on Solaris to match g++ >= 9.
 if (UNIX AND ${CMAKE_SYSTEM_NAME} MATCHES "SunOS")
           add_definitions("-D_FILE_OFFSET_BITS=64")
 endif()
 
 # Work around a broken bfd ld behavior. When linking a binary with a
 # foo.so library, it will try to find any library that foo.so uses and
 # check its symbols. This is wasteful (the check was done when foo.so
 # was created) and can fail since it is not the dynamic linker and
 # doesn't know how to handle search paths correctly.
-if (UNIX AND NOT APPLE AND NOT ${CMAKE_SYSTEM_NAME} MATCHES "SunOS|AIX")
+if (UNIX AND NOT APPLE AND NOT CMAKE_SYSTEM_NAME MATCHES "SunOS|AIX|OS390")
   set(CMAKE_EXE_LINKER_FLAGS
       "${CMAKE_EXE_LINKER_FLAGS} -Wl,-allow-shlib-undefined")
 endif()
 
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
 
 include_directories( ${LLVM_INCLUDE_DIR} ${LLVM_MAIN_INCLUDE_DIR})
 

llvm/cmake/modules/AddLLVM.cmake

 
 function(add_link_opts target_name)
   # Don't use linker optimizations in debug builds since it slows down the
   # linker in a context where the optimizations are not important.
   if (NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG")
 
     # Pass -O3 to the linker. This enabled different optimizations on different
     # linkers.
-    if(NOT (${CMAKE_SYSTEM_NAME} MATCHES "Darwin|SunOS|AIX" OR WIN32))
+    if(NOT (CMAKE_SYSTEM_NAME MATCHES "Darwin|SunOS|AIX|OS390" OR WIN32))
       set_property(TARGET ${target_name} APPEND_STRING PROPERTY
                    LINK_FLAGS " -Wl,-O3")
     endif()
 
     if(LLVM_LINKER_IS_GOLD)
       # With gold gc-sections is always safe.
       set_property(TARGET ${target_name} APPEND_STRING PROPERTY
                    LINK_FLAGS " -Wl,--gc-sections")
if(NOT LLVM_NO_DEAD_STRIP)
         # Solaris 11.4.
         include(CheckLinkerFlag)
         check_linker_flag("-Wl,-z,discard-unused=sections" LINKER_SUPPORTS_Z_DISCARD_UNUSED)
         if (LINKER_SUPPORTS_Z_DISCARD_UNUSED)
           set_property(TARGET ${target_name} APPEND_STRING PROPERTY
                        LINK_FLAGS " -Wl,-z,discard-unused=sections")
         endif()
       elseif(NOT WIN32 AND NOT LLVM_LINKER_IS_GOLD AND
-             NOT ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD|AIX")
+             NOT CMAKE_SYSTEM_NAME MATCHES "OpenBSD|AIX|OS390")
         # Object files are compiled with -ffunction-data-sections.
         # Versions of bfd ld < 2.23.1 have a bug in --gc-sections that breaks
         # tools that use plugins. Always pass --gc-sections once we require
         # a newer linker.
+        # TODO Revisit this later on z/OS.
         set_property(TARGET ${target_name} APPEND_STRING PROPERTY
                      LINK_FLAGS " -Wl,--gc-sections")
       endif()
     else() #LLVM_NO_DEAD_STRIP
       if(${CMAKE_SYSTEM_NAME} MATCHES "AIX")
         set_property(TARGET ${target_name} APPEND_STRING PROPERTY
                      LINK_FLAGS " -Wl,-bnogc")
       endif()

llvm/cmake/modules/GetHostTriple.cmake

 # Returns the host triple.
 # Invokes config.guess
 
 function( get_host_triple var )
   if( MSVC )
     if( CMAKE_SIZEOF_VOID_P EQUAL 8 )
       set( value "x86_64-pc-windows-msvc" )
     else()
       set( value "i686-pc-windows-msvc" )
     endif()
   elseif( MINGW AND NOT MSYS )
     if( CMAKE_SIZEOF_VOID_P EQUAL 8 )
       set( value "x86_64-w64-windows-gnu" )
     else()
       set( value "i686-pc-windows-gnu" )
     endif()
-  elseif( CMAKE_HOST_SYSTEM_NAME STREQUAL AIX )
+  elseif( CMAKE_SYSTEM_NAME MATCHES "OS390" )
+    set( value "s390x-ibm-zos" )
+  elseif( CMAKE_SYSTEM_NAME STREQUAL AIX )
     # We defer to dynamic detection of the host AIX version.
     if( CMAKE_SIZEOF_VOID_P EQUAL 8 )
       set( value "powerpc64-ibm-aix" )
     else()
       set( value "powerpc-ibm-aix" )
     endif()
   else( MSVC )
     if(CMAKE_HOST_SYSTEM_NAME STREQUAL Windows AND NOT MSYS)

llvm/cmake/modules/HandleLLVMOptions.cmake

if(FUCHSIA OR UNIX)
     else()
       set(LLVM_HAVE_LINK_VERSION_SCRIPT 1)
     endif()
   else(FUCHSIA OR UNIX)
     MESSAGE(SEND_ERROR "Unable to determine platform")
   endif(FUCHSIA OR UNIX)
 endif(WIN32)
 
+if (CMAKE_SYSTEM_NAME MATCHES "OS390")
+  set(LLVM_HAVE_LINK_VERSION_SCRIPT 0)
+endif()
+
 set(EXEEXT ${CMAKE_EXECUTABLE_SUFFIX})
 set(LTDL_SHLIB_EXT ${CMAKE_SHARED_LIBRARY_SUFFIX})
 
 # We use *.dylib rather than *.so on darwin.
 set(LLVM_PLUGIN_EXT ${CMAKE_SHARED_LIBRARY_SUFFIX})
 
 if(APPLE)
   if(LLVM_ENABLE_LLD AND LLVM_ENABLE_LTO)
elseif(CMAKE_CXX_COMPILER_ID MATCHES "XL")
     # we can limit the processing for archive members to only those that are otherwise referenced.
     append("-bcdtors:mbr"
            CMAKE_EXE_LINKER_FLAGS CMAKE_MODULE_LINKER_FLAGS CMAKE_SHARED_LINKER_FLAGS)
   endif()
 endif()
 
 # Pass -Wl,-z,defs. This makes sure all symbols are defined. Otherwise a DSO
 # build might work on ELF but fail on MachO/COFF.
-if(NOT (${CMAKE_SYSTEM_NAME} MATCHES "Darwin|FreeBSD|OpenBSD|DragonFly|AIX|SunOS" OR
+if(NOT (CMAKE_SYSTEM_NAME MATCHES "Darwin|FreeBSD|OpenBSD|DragonFly|AIX|SunOS|OS390" OR
         WIN32 OR CYGWIN) AND
    NOT LLVM_USE_SANITIZER)
   set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,-z,defs")
 endif()
 
 # Pass -Wl,-z,nodelete. This makes sure our shared libraries are not unloaded
 # by dlclose(). We need that since the CLI API relies on cross-references
 # between global objects which became horribly broken when one of the libraries
CMAKE_DEPENDENT_OPTION(LLVM_EXPORT_SYMBOLS_FOR_PLUGINS
        "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()
 if(LLVM_LINK_LLVM_DYLIB AND LLVM_EXPORT_SYMBOLS_FOR_PLUGINS)
   message(FATAL_ERROR "LLVM_LINK_LLVM_DYLIB not compatible with LLVM_EXPORT_SYMBOLS_FOR_PLUGINS")
 endif()
 
 # By default we should enable LLVM_ENABLE_IDE only for multi-configuration
 # generators. This option disables optional build system features that make IDEs
 # less usable.
 set(LLVM_ENABLE_IDE_default OFF)
 if (CMAKE_CONFIGURATION_TYPES)
   set(LLVM_ENABLE_IDE_default ON)
 endif()
 option(LLVM_ENABLE_IDE
        "Disable optional build system features that cause problems for IDE generators"