From 91960900f86ebfe2bf5f48af5363cdef02b5d005 Mon Sep 17 00:00:00 2001
From: Evgeniy Stepanov <eugeni.stepanov@gmail.com>
Date: Tue, 5 May 2015 20:13:39 +0000
Subject: [PATCH] Build ASan runtime library with -z global on Android.

llvm-svn: 236537
---
 compiler-rt/cmake/Modules/AddCompilerRT.cmake |  4 ++--
 compiler-rt/cmake/config-ix.cmake             | 12 ++++++++++++
 compiler-rt/lib/asan/CMakeLists.txt           | 14 ++++++++++++++
 3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/compiler-rt/cmake/Modules/AddCompilerRT.cmake b/compiler-rt/cmake/Modules/AddCompilerRT.cmake
index a7782a194847..a4b4df356de7 100644
--- a/compiler-rt/cmake/Modules/AddCompilerRT.cmake
+++ b/compiler-rt/cmake/Modules/AddCompilerRT.cmake
@@ -47,13 +47,13 @@ endmacro()
 #                         OUTPUT_NAME <output library name>)
 macro(add_compiler_rt_runtime name arch type)
   if(CAN_TARGET_${arch})
-    parse_arguments(LIB "SOURCES;CFLAGS;DEFS;OUTPUT_NAME" "" ${ARGN})
+    parse_arguments(LIB "SOURCES;CFLAGS;LINKFLAGS;DEFS;OUTPUT_NAME" "" ${ARGN})
     add_library(${name} ${type} ${LIB_SOURCES})
     # Setup compile flags and definitions.
     set_target_compile_flags(${name}
       ${TARGET_${arch}_CFLAGS} ${LIB_CFLAGS})
     set_target_link_flags(${name}
-      ${TARGET_${arch}_CFLAGS} ${LIB_CFLAGS})
+      ${TARGET_${arch}_CFLAGS} ${LIB_CFLAGS} ${LIB_LINKFLAGS})
     set_property(TARGET ${name} APPEND PROPERTY
       COMPILE_DEFINITIONS ${LIB_DEFS})
     # Setup correct output directory in the build tree.
diff --git a/compiler-rt/cmake/config-ix.cmake b/compiler-rt/cmake/config-ix.cmake
index 5574dc2a3e9b..e62715ea6f8f 100644
--- a/compiler-rt/cmake/config-ix.cmake
+++ b/compiler-rt/cmake/config-ix.cmake
@@ -4,6 +4,13 @@ include(CheckLibraryExists)
 include(CheckSymbolExists)
 include(TestBigEndian)
 
+function(check_linker_flag flag out_var)
+  cmake_push_check_state()
+  set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} ${flag}")
+  check_cxx_compiler_flag("" ${out_var})
+  cmake_pop_check_state()
+endfunction()
+
 # CodeGen options.
 check_cxx_compiler_flag(-fPIC                COMPILER_RT_HAS_FPIC_FLAG)
 check_cxx_compiler_flag(-fPIE                COMPILER_RT_HAS_FPIE_FLAG)
@@ -59,6 +66,11 @@ check_library_exists(m pow "" COMPILER_RT_HAS_LIBM)
 check_library_exists(pthread pthread_create "" COMPILER_RT_HAS_LIBPTHREAD)
 check_library_exists(stdc++ __cxa_throw "" COMPILER_RT_HAS_LIBSTDCXX)
 
+# Linker flags.
+if(ANDROID)
+  check_linker_flag("-Wl,-z,global" COMPILER_RT_HAS_Z_GLOBAL)
+endif()
+
 # Architectures.
 
 # List of all architectures we can target.
diff --git a/compiler-rt/lib/asan/CMakeLists.txt b/compiler-rt/lib/asan/CMakeLists.txt
index e09c94d8d2d7..d9bddb3c67d9 100644
--- a/compiler-rt/lib/asan/CMakeLists.txt
+++ b/compiler-rt/lib/asan/CMakeLists.txt
@@ -37,9 +37,22 @@ append_no_rtti_flag(ASAN_CFLAGS)
 set(ASAN_COMMON_DEFINITIONS
   ASAN_HAS_EXCEPTIONS=1)
 
+set(ASAN_DYNAMIC_LINK_FLAGS)
+
 if(ANDROID)
   list(APPEND ASAN_COMMON_DEFINITIONS
     ASAN_LOW_MEMORY=1)
+# On Android, -z global does not do what it is documented to do.
+# On Android, -z global moves the library ahead in the lookup order,
+# placing it right after the LD_PRELOADs. This is used to compensate for the fact
+# that Android linker does not look at the dependencies of the main executable
+# that aren't dependencies of the current DSO when resolving symbols from said DSO.
+# As a net result, this allows running ASan executables without LD_PRELOAD-ing the
+# ASan runtime library.
+# The above is applicable to L MR1 or newer.
+  if (COMPILER_RT_HAS_Z_GLOBAL)
+    list(APPEND ASAN_DYNAMIC_LINK_FLAGS -Wl,-z,global)
+  endif()
 endif()
 
 set(ASAN_DYNAMIC_DEFINITIONS
@@ -143,6 +156,7 @@ else()
               $<TARGET_OBJECTS:RTUbsan_cxx.${arch}>
               ${ASAN_COMMON_RUNTIME_OBJECTS}
       CFLAGS ${ASAN_DYNAMIC_CFLAGS}
+      LINKFLAGS ${ASAN_DYNAMIC_LINK_FLAGS}
       DEFS ${ASAN_DYNAMIC_DEFINITIONS})
     target_link_libraries(clang_rt.asan-dynamic-${arch} ${ASAN_DYNAMIC_LIBS})
     add_dependencies(asan clang_rt.asan-dynamic-${arch})