[scudo][standalone] Add shared library to makefile

[cryptoad]

Summary

Since we are looking to remove the old Scudo, we have to have a .so for
parity purposes as some platforms use it.

I tested this on Fuchsia & Linux, not on Android though.

[hctim]

LGTM w/ nit

compiler-rt/lib/scudo/standalone/CMakeLists.txt

134

Shouldn't this be -pthread to ldflags, not linking lpthread?

i.e.

append_list_if(COMPILER_RT_HAS_LIBPTHREAD -pthread SCUDO_LINK_FLAGS)

[cryptoad]

compiler-rt/lib/scudo/standalone/CMakeLists.txt

134

Right, thanks! Not sure how it worked without the - either.

[cryptoad]

Updating -pthread

compiler-rt/lib/scudo/standalone/CMakeLists.txt

 list(APPEND SCUDO_CFLAGS
   -Werror=conversion
   -Wall
   -nostdinc++)
 
 # Remove -stdlib= which is unused when passing -nostdinc++.
 string(REGEX REPLACE "-stdlib=[a-zA-Z+]*" "" CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS})
 
-append_list_if(COMPILER_RT_HAS_FFREESTANDING_FLAG -ffreestanding SCUDO_CFLAGS)
-
 append_list_if(COMPILER_RT_HAS_FVISIBILITY_HIDDEN_FLAG -fvisibility=hidden SCUDO_CFLAGS)
 
+append_list_if(COMPILER_RT_HAS_FNO_EXCEPTIONS_FLAG -fno-exceptions SCUDO_CFLAGS)
+
 append_list_if(COMPILER_RT_HAS_WNO_PEDANTIC -Wno-pedantic SCUDO_CFLAGS)
 
 # FIXME: find cleaner way to agree with GWPAsan flags
 append_list_if(COMPILER_RT_HAS_FNO_LTO_FLAG -fno-lto SCUDO_CFLAGS)
 
 if (COMPILER_RT_HAS_GWP_ASAN)
   append_list_if(COMPILER_RT_HAS_OMIT_FRAME_POINTER_FLAG -fno-omit-frame-pointer
                 SCUDO_CFLAGS)
   append_list_if(COMPILER_RT_HAS_OMIT_FRAME_POINTER_FLAG
                 -mno-omit-leaf-frame-pointer SCUDO_CFLAGS)
 endif() # COMPILER_RT_HAS_GWP_ASAN
 
 if(COMPILER_RT_DEBUG)
   list(APPEND SCUDO_CFLAGS -O0)
 else()
   list(APPEND SCUDO_CFLAGS -O3)
 endif()
 
 set(SCUDO_LINK_FLAGS)
 
 list(APPEND SCUDO_LINK_FLAGS -Wl,-z,defs,-z,now,-z,relro)
 
-append_list_if(COMPILER_RT_HAS_NODEFAULTLIBS_FLAG -nodefaultlibs SCUDO_LINK_FLAGS)
+list(APPEND SCUDO_LINK_FLAGS -ffunction-sections -fdata-sections -Wl,--gc-sections)
+
+# We don't use the C++ standard library, so avoid including it by mistake.
+append_list_if(COMPILER_RT_HAS_NOSTDLIBXX_FLAG -nostdlib++ SCUDO_LINK_FLAGS)
 
 if(ANDROID)
   list(APPEND SCUDO_CFLAGS -fno-emulated-tls)
 
 # Put the shared library in the global group. For more details, see
 # android-changes-for-ndk-developers.md#changes-to-library-search-order
   append_list_if(COMPILER_RT_HAS_Z_GLOBAL -Wl,-z,global SCUDO_LINK_FLAGS)
 endif()

 set(SCUDO_OBJECT_LIBS)
 
 if (COMPILER_RT_HAS_GWP_ASAN)
   list(APPEND SCUDO_OBJECT_LIBS
        RTGwpAsan RTGwpAsanBacktraceLibc RTGwpAsanSegvHandler)
   list(APPEND SCUDO_CFLAGS -DGWP_ASAN_HOOKS)
 endif()
 
+set(SCUDO_LINK_LIBS)
+
+append_list_if(COMPILER_RT_HAS_LIBPTHREAD pthread SCUDO_LINK_LIBS)
+
+append_list_if(FUCHSIA zircon SCUDO_LINK_LIBS)
+
 if(COMPILER_RT_HAS_SCUDO_STANDALONE)
   add_compiler_rt_object_libraries(RTScudoStandalone
     ARCHS ${SCUDO_STANDALONE_SUPPORTED_ARCH}
     SOURCES ${SCUDO_SOURCES}
     ADDITIONAL_HEADERS ${SCUDO_HEADERS}
     CFLAGS ${SCUDO_CFLAGS})
   add_compiler_rt_object_libraries(RTScudoStandaloneCWrappers
     ARCHS ${SCUDO_STANDALONE_SUPPORTED_ARCH}
add_compiler_rt_runtime(clang_rt.scudo_standalone_cxx
     STATIC
     ARCHS ${SCUDO_STANDALONE_SUPPORTED_ARCH}
     SOURCES ${SCUDO_SOURCES_CXX_WRAPPERS}
     ADDITIONAL_HEADERS ${SCUDO_HEADERS}
     CFLAGS ${SCUDO_CFLAGS}
     OBJECT_LIBS ${SCUDO_OBJECT_LIBS}
     PARENT_TARGET scudo_standalone)
 
+  add_compiler_rt_runtime(clang_rt.scudo_standalone
+    SHARED
+    ARCHS ${SCUDO_STANDALONE_SUPPORTED_ARCH}
+    SOURCES ${SCUDO_SOURCES} ${SCUDO_SOURCES_C_WRAPPERS} ${SCUDO_SOURCES_CXX_WRAPPERS}
+    ADDITIONAL_HEADERS ${SCUDO_HEADERS}
+    CFLAGS ${SCUDO_CFLAGS}
+    OBJECT_LIBS ${SCUDO_OBJECT_LIBS}
+    LINK_FLAGS ${SCUDO_LINK_FLAGS}
+    LINK_LIBS ${SCUDO_LINK_LIBS}
+    PARENT_TARGET scudo_standalone)
+
   add_subdirectory(benchmarks)
   if(COMPILER_RT_INCLUDE_TESTS)
     add_subdirectory(tests)
   endif()
 endif()