add_symbols_versioning

This patch adds a very simple linker script to version the lib's symbols
and thus trying to avoid crashes if an application loads two different
LLVM versions (as long as they do not share data between them).

Note that we deliberately *don't* make LLVM_3.9 depend on LLVM_3.8:
they're incompatible and the whole point of this patch is
to tell the linker that.

Author: Rebecca N. Palmer <rebecca_palmer@zoho.com>
Author: Lisandro Damían Nicanor Pérez Meyer <lisandro@debian.org>
Bug-Debian: https://bugs.debian.org/848368

Gbp-Pq: Name add_symbols_versioning.patch

diff --git a/cmake/modules/AddLLVM.cmake b/cmake/modules/AddLLVM.cmake
index cb4171c9bc8825a1c8ef88a812c42d27d2d0cb3a..182486a9a3ebad49b33f2ac48291e95b94ec7e24 100644 (file)
--- a/cmake/modules/AddLLVM.cmake
+++ b/cmake/modules/AddLLVM.cmake
@@ -82,7 +82,7 @@ function(add_llvm_symbol_exports target_name export_file)
     set(native_export_file "${target_name}.exports")
     # FIXME: Don't write the "local:" line on OpenBSD.
     add_custom_command(OUTPUT ${native_export_file}
-      COMMAND echo "{" > ${native_export_file}
+      COMMAND echo "LLVM_4.0 {" > ${native_export_file}
       COMMAND grep -q "[[:alnum:]]" ${export_file} && echo "  global:" >> ${native_export_file} || :
       COMMAND sed -e "s/$/;/" -e "s/^/    /" < ${export_file} >> ${native_export_file}
       COMMAND echo "  local: *;" >> ${native_export_file}

diff --git a/tools/llvm-shlib/CMakeLists.txt b/tools/llvm-shlib/CMakeLists.txt
index 73b3a37b98967905096cd30996dbeb5191556e08..559ae270f842e09e11c34b6662e11e1492ad389b 100644 (file)
--- a/tools/llvm-shlib/CMakeLists.txt
+++ b/tools/llvm-shlib/CMakeLists.txt
@@ -40,7 +40,7 @@ set_property(TARGET LLVM PROPERTY VERSION "1") # Append .1 to SONAME
 list(REMOVE_DUPLICATES LIB_NAMES)
 if("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux" OR MINGW) # FIXME: It should be "GNU ld for elf"
   # GNU ld doesn't resolve symbols in the version script.
-  set(LIB_NAMES -Wl,--whole-archive ${LIB_NAMES} -Wl,--no-whole-archive)
+  set(LIB_NAMES -Wl,--version-script,${CMAKE_CURRENT_SOURCE_DIR}/simple_version_script.map -Wl,--whole-archive ${LIB_NAMES} -Wl,--no-whole-archive)
 elseif("${CMAKE_SYSTEM_NAME}" STREQUAL "Darwin")
   set(LIB_NAMES -Wl,-all_load ${LIB_NAMES})
 endif()

diff --git a/tools/llvm-shlib/simple_version_script.map b/tools/llvm-shlib/simple_version_script.map
new file mode 100644 (file)
index 0000000..816fb3c
--- /dev/null
+++ b/tools/llvm-shlib/simple_version_script.map
@@ -0,0 +1 @@
+LLVM_4.0 { global: *; };