cmake: provide flag that enables 'log enable --stack' to provide useful file/function info on POSIX systems

Adding the following flag to a cmake line:
-DLLDB_EXPORT_ALL_SYMBOLS=TRUE

will cause all symbols to be exported from liblldb.  This enables the llvm
backtrace mechanism to see and report backtrace symbols properly when using
(lldb) log enable --stack ...

Prior to this change, only the SB API symbols would show up on Linux and other
systems that use a public-symbols-based backtrace lookup mechanism.

log enable --stack ... is a very handy, quick way to understand the flow
of how some log lines are getting hit within lldb without having to hook
up a top-level debugger over your current debug session.

llvm-svn: 250299

1 files changed, 15 insertions, 1 deletions

diff --git a/lldb/source/API/CMakeLists.txt b/lldb/source/API/CMakeLists.txt
index 271afa9c9a8..06a26e17c92 100644
--- a/lldb/source/API/CMakeLists.txt
+++ b/lldb/source/API/CMakeLists.txt
@@ -82,7 +82,21 @@ set_target_properties(liblldb
   )
 
 if (NOT CMAKE_SYSTEM_NAME MATCHES "Windows")
-  add_llvm_symbol_exports(liblldb ${CMAKE_CURRENT_SOURCE_DIR}/liblldb.exports)
+  if (NOT LLDB_EXPORT_ALL_SYMBOLS)
+    # If we're not exporting all symbols, we'll want to explicitly set
+    # the exported symbols here.  This prevents 'log enable --stack ...'
+    # from working on some systems but limits the liblldb size.
+    MESSAGE("-- Symbols (liblldb): only exporting liblldb.exports symbols")
+    add_llvm_symbol_exports(liblldb ${CMAKE_CURRENT_SOURCE_DIR}/liblldb.exports)
+  else()
+    # Don't use an explicit export.  Instead, tell the linker to
+    # export all symbols.
+    MESSAGE("-- Symbols (liblldb): exporting all symbols")
+    # Darwin linker doesn't need this extra step.
+    if (NOT CMAKE_SYSTEM_NAME MATCHES "Darwin")
+      lldb_append_link_flags(liblldb "-Wl,--export-dynamic")
+    endif()
+  endif()
 endif()
 
 if ( CMAKE_SYSTEM_NAME MATCHES "Windows" )