[PATCH] D70868: [libunwind] Emit dependent libraries only when detected by CMake

[Michał Górny via Phabricator via cfe-commits]

mgorny created this revision.
mgorny added reviewers: phosek, ldionne.
Herald added subscribers: jfb, dexonsmith, christof, krytarowski, srhines.

996e62eef75 added Linux-specific dependent libraries to libunwind
sources.  As a result, building libunwind with modern LLD on *BSD
started failing due to trying to link libdl.  Instead, add those
libraries only if they were detected by CMake.

While technically we could create a long list of systems that need -ldl
and -lpthread, maintaining a duplicate list makes little sense when
CMake needs to detect it for non-LLD systems anyway.  Remove existing
system exceptions since they should be covered by the CMake check
anyway.

Remove -D_LIBUNWIND_HAS_COMMENT_LIB_PRAGMA since it is no longer
explicitly needed, if we make the library-specific defines dependent
on presence of this pragma support.


https://reviews.llvm.org/D70868

Files:
  libunwind/CMakeLists.txt
  libunwind/src/AddressSpace.hpp
  libunwind/src/RWMutex.hpp


Index: libunwind/src/RWMutex.hpp
===================================================================
--- libunwind/src/RWMutex.hpp
+++ libunwind/src/RWMutex.hpp
@@ -17,7 +17,7 @@
 #include <windows.h>
 #elif !defined(_LIBUNWIND_HAS_NO_THREADS)
 #include <pthread.h>
-#if defined(__unix__) && !defined(__ANDROID__) && defined(__ELF__) && defined(_LIBUNWIND_HAS_COMMENT_LIB_PRAGMA)
+#if defined(__ELF__) && defined(_LIBUNWIND_LINK_PTHREAD_LIB)
 #pragma comment(lib, "pthread")
 #endif
 #endif
Index: libunwind/src/AddressSpace.hpp
===================================================================
--- libunwind/src/AddressSpace.hpp
+++ libunwind/src/AddressSpace.hpp
@@ -27,7 +27,7 @@
 
 #if _LIBUNWIND_USE_DLADDR
 #include <dlfcn.h>
-#if defined(__unix__) && defined(__ELF__) && defined(_LIBUNWIND_HAS_COMMENT_LIB_PRAGMA)
+#if defined(__ELF__) && defined(_LIBUNWIND_LINK_DL_LIB)
 #pragma comment(lib, "dl")
 #endif
 #endif
Index: libunwind/CMakeLists.txt
===================================================================
--- libunwind/CMakeLists.txt
+++ libunwind/CMakeLists.txt
@@ -352,7 +352,12 @@
 endif()
 
 if (LIBUNWIND_HAS_COMMENT_LIB_PRAGMA)
-  add_definitions(-D_LIBUNWIND_HAS_COMMENT_LIB_PRAGMA)
+  if (LIBUNWIND_HAS_DL_LIB)
+    add_definitions(-D_LIBUNWIND_LINK_DL_LIB)
+  endif()
+  if (LIBUNWIND_HAS_PTHREAD_LIB)
+    add_definitions(-D_LIBUNWIND_LINK_PTHREAD_LIB)
+  endif()
 endif()
 
 #===============================================================================


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