[gn build] build libclang_rt.ubsan_osx_dynamic.dylib on mac

[thakis]

cleanup

[aeubanks]

compiler-rt/lib/ubsan/CMakeLists.txt says there's also a static library on mac, but if this works with -fsanitize=undefined then I guess this is good enough

[thakis]

We only ship the dynamic one in the chromium clang package, and it's enough to make things work.

...oh, looks like there's -static-libsan to pick the static lib, but the default is the dynamic one on mac (and fuchsia, and android): http://llvm-cs.pcc.me.uk/tools/clang/lib/Driver/SanitizerArgs.cpp#737 So we should probably try to get the shared version building on android too at least. And -static-libsan won't work in the GN build on mac until the static lib is built too.

And it looks like http://llvm-cs.pcc.me.uk/tools/clang/lib/Driver/SanitizerArgs.cpp#267 , http://llvm-cs.pcc.me.uk/tools/clang/lib/Driver/ToolChains/Darwin.cpp#1187 mean that fsanitize-minimal-runtime won't work for now either.

I'll update the patch description with this.

llvm/utils/gn/secondary/compiler-rt/lib/BUILD.gn

 group("lib") {
   deps = [
     "//compiler-rt/lib/asan:ignorelist($host_toolchain)",
     "//compiler-rt/lib/cfi:ignorelist($host_toolchain)",
   ]
   if (current_os == "linux") {
     deps += [ "//compiler-rt/lib/msan" ]
   }
-  if (current_os == "linux" || current_os == "android") {
-    deps += [
-      "//compiler-rt/lib/ubsan",
-      "//compiler-rt/lib/ubsan_minimal",
-    ]
+  if (current_os == "android" || current_os == "linux" || current_os == "mac") {
+    deps += [ "//compiler-rt/lib/ubsan" ]
+  }
+  if (current_os == "android" || current_os == "linux") {
+    deps += [ "//compiler-rt/lib/ubsan_minimal" ]
   }
   if (current_os != "win" && current_os != "baremetal") {
     deps += [ "//compiler-rt/lib/asan" ]
     if (current_cpu == "x64" || current_cpu == "arm64") {
       deps += [ "//compiler-rt/lib/tsan/rtl" ]
     }
   }
   if (current_os != "win") {
     deps += [ "//compiler-rt/lib/builtins" ]
   }
   if (current_os != "baremetal") {
     deps += [ "//compiler-rt/lib/profile" ]
   }
 }

llvm/utils/gn/secondary/compiler-rt/lib/ubsan/BUILD.gn

 import("//compiler-rt/target.gni")
 
 group("ubsan") {
+  if (current_os == "mac") {
+    deps = [ ":ubsan_shared_library" ]
+  } else {
     deps = [
       ":ubsan_standalone",
       ":ubsan_standalone_cxx",
     ]
   }
+}
 
 source_set("sources") {
   configs -= [ "//llvm/utils/gn/build:llvm_code" ]
   configs += [ "//llvm/utils/gn/build:crt_code" ]
   defines = [ "UBSAN_CAN_USE_CXXABI" ]
   deps = [
     "//compiler-rt/lib/interception:sources",
     "//compiler-rt/lib/sanitizer_common:sources",
sources = [
     "ubsan_handlers_cxx.cpp",
     "ubsan_handlers_cxx.h",
     "ubsan_type_hash.cpp",
     "ubsan_type_hash_itanium.cpp",
     "ubsan_type_hash_win.cpp",
   ]
 }
 
-# FIXME: Make ubsan_standalone work on mac.
-if (current_os != "mac") {
+if (current_os == "mac") {
+  shared_library("ubsan_shared_library") {
+    output_dir = crt_current_out_dir
+    output_name = "clang_rt.ubsan_osx_dynamic"
+    deps = [
+      ":cxx_sources",
+      ":sources",
+      ":standalone_sources",
+      "//compiler-rt/lib/interception:sources",
+      "//compiler-rt/lib/sanitizer_common:sources",
+    ]
+    # The -U flags below correspond to the add_weak_symbols() calls in CMake.
+    ldflags = [
+      "-lc++",
+      "-lc++abi",
+
+      # ubsan
+      "-Wl,-U,___ubsan_default_options",
+
+      # sanitizer_common
+      "-Wl,-U,___sanitizer_free_hook",
+      "-Wl,-U,___sanitizer_malloc_hook",
+      "-Wl,-U,___sanitizer_report_error_summary",
+      "-Wl,-U,___sanitizer_sandbox_on_notify",
+      "-Wl,-U,___sanitizer_symbolize_code",
+      "-Wl,-U,___sanitizer_symbolize_data",
+      "-Wl,-U,___sanitizer_symbolize_demangle",
+      "-Wl,-U,___sanitizer_symbolize_flush",
+      "-Wl,-U,___sanitizer_symbolize_set_demangle",
+      "-Wl,-U,___sanitizer_symbolize_set_inline_frames",
+
+      # FIXME: better
+      "-Wl,-install_name,@rpath/libclang_rt.ubsan_osx_dynamic.dylib",
+    ]
+    # FIXME: -Wl,-rpath
+  }
+} else {
   static_library("ubsan_standalone") {
     output_dir = crt_current_out_dir
     output_name = "clang_rt.ubsan_standalone$crt_current_target_suffix"
     complete_static_lib = true
     configs -= [
       "//llvm/utils/gn/build:llvm_code",
       "//llvm/utils/gn/build:thin_archive",
     ]