[runtimes] Support ELF dependent libraries feature
As of r360984, LLD supports dependent libraries feature for ELF.
libunwind, libc++abi and libc++ have library dependencies: libdl librt
and libpthread, which means that when libunwind and libc++ are being
statically linked (using -static-libstdc++ flag), user has to manually
specify -ldl -lpthread which is onerous.
This change includes the lib pragma to specify the library dependencies
directly in the source that uses those libraries. This doesn't make any
difference when using linkers that don't support dependent libraries.
However, when using LLD that has dependent libraries feature, users no
longer have to manually specifying library dependencies when using
static linking, linker will pick the library automatically.
Differential Revision: https://reviews.llvm.org/D62090
git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@362048 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/src/cxa_guard_impl.h b/src/cxa_guard_impl.h
index 412099e..bd6b15f 100644
--- a/src/cxa_guard_impl.h
+++ b/src/cxa_guard_impl.h
@@ -49,6 +49,11 @@
#include <stdlib.h>
#include <__threading_support>
+#ifndef _LIBCXXABI_HAS_NO_THREADS
+#if defined(__unix__) && defined(__ELF__) && defined(__clang__)
+#pragma comment(lib, "pthread")
+#endif
+#endif
// To make testing possible, this header is included from both cxa_guard.cpp
// and a number of tests.
diff --git a/src/cxa_thread_atexit.cpp b/src/cxa_thread_atexit.cpp
index da1df86..38787f1 100644
--- a/src/cxa_thread_atexit.cpp
+++ b/src/cxa_thread_atexit.cpp
@@ -9,6 +9,12 @@
#include "abort_message.h"
#include "cxxabi.h"
#include <__threading_support>
+#ifndef _LIBCXXABI_HAS_NO_THREADS
+#if defined(__unix__) && defined(__ELF__) && defined(__clang__)
+#pragma comment(lib, "pthread")
+#endif
+#endif
+
#include <cstdlib>
namespace __cxxabiv1 {
diff --git a/src/fallback_malloc.cpp b/src/fallback_malloc.cpp
index 8ec1eee..bae0fa4 100644
--- a/src/fallback_malloc.cpp
+++ b/src/fallback_malloc.cpp
@@ -12,6 +12,11 @@
#include "fallback_malloc.h"
#include <__threading_support>
+#ifndef _LIBCXXABI_HAS_NO_THREADS
+#if defined(__unix__) && defined(__ELF__) && defined(__clang__)
+#pragma comment(lib, "pthread")
+#endif
+#endif
#include <cstdlib> // for malloc, calloc, free
#include <cstring> // for memset
