[PATCH] D115674: [CMake][compiler-rt] Provide a dedicated option for LLVM unwinder

[Petr Hosek via Phabricator via llvm-commits]

phosek updated this revision to Diff 436511.
phosek retitled this revision from "[runtime] Build compiler-rt with --unwindlib=none" to "[CMake][compiler-rt] Provide a dedicated option for LLVM unwinder".
phosek edited the summary of this revision.
Herald added a subscriber: cryptoad.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D115674/new/

https://reviews.llvm.org/D115674

Files:
  compiler-rt/CMakeLists.txt
  compiler-rt/cmake/config-ix.cmake
  compiler-rt/lib/scudo/standalone/CMakeLists.txt


Index: compiler-rt/lib/scudo/standalone/CMakeLists.txt
===================================================================
--- compiler-rt/lib/scudo/standalone/CMakeLists.txt
+++ compiler-rt/lib/scudo/standalone/CMakeLists.txt
@@ -36,6 +36,7 @@
 
 # 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)
+append_list_if(CXX_SUPPORTS_UNWINDLIB_NONE_FLAG --unwindlib=none SCUDO_LINK_FLAGS)
 
 if(ANDROID)
   list(APPEND SCUDO_CFLAGS -fno-emulated-tls)
Index: compiler-rt/cmake/config-ix.cmake
===================================================================
--- compiler-rt/cmake/config-ix.cmake
+++ compiler-rt/cmake/config-ix.cmake
@@ -4,9 +4,19 @@
 include(CheckCXXCompilerFlag)
 include(CheckIncludeFiles)
 include(CheckLibraryExists)
+include(LLVMCheckCompilerLinkerFlag)
 include(CheckSymbolExists)
 include(TestBigEndian)
 
+# The compiler driver may be implicitly trying to link against libunwind.
+# This is normally ok (libcxx relies on an unwinder), but if libunwind is
+# built in the same cmake invocation as compiler-rt and we're using the
+# in tree version of runtimes, we'd be linking against the just-built
+# libunwind (and the compiler implicit -lunwind wouldn't succeed as the newly
+# built libunwind isn't installed yet). For those cases, it'd be good to
+# link with --uwnindlib=none. Check if that option works.
+llvm_check_compiler_linker_flag(C "--unwindlib=none" CXX_SUPPORTS_UNWINDLIB_NONE_FLAG)
+
 check_library_exists(c fopen "" COMPILER_RT_HAS_LIBC)
 if (COMPILER_RT_USE_BUILTINS_LIBRARY)
   include(HandleCompilerRT)
Index: compiler-rt/CMakeLists.txt
===================================================================
--- compiler-rt/CMakeLists.txt
+++ compiler-rt/CMakeLists.txt
@@ -31,6 +31,7 @@
 include(SetPlatformToolchainTools)
 include(base-config-ix)
 include(CompilerRTUtils)
+include(CMakeDependentOption)
 
 option(COMPILER_RT_BUILD_BUILTINS "Build builtins" ON)
 mark_as_advanced(COMPILER_RT_BUILD_BUILTINS)
@@ -211,6 +212,11 @@
 set_property(CACHE SANITIZER_TEST_CXX PROPERTY STRINGS ;${CXXLIBS})
 handle_default_cxx_lib(SANITIZER_TEST_CXX)
 
+option(COMPILER_RT_USE_LLVM_UNWINDER "Use the LLVM unwinder." OFF)
+cmake_dependent_option(COMPILER_RT_ENABLE_STATIC_UNWINDER
+  "Statically link the LLVM unwinder." OFF
+  "COMPILER_RT_USE_LLVM_UNWINDER" OFF)
+
 set(DEFAULT_SANITIZER_USE_STATIC_LLVM_UNWINDER OFF)
 if (FUCHSIA)
   set(DEFAULT_SANITIZER_USE_STATIC_LLVM_UNWINDER ON)
@@ -504,8 +510,23 @@
 list(APPEND COMPILER_RT_COMMON_CFLAGS ${stdlib_flag})
 list(APPEND COMPILER_RT_COMMON_LINK_FLAGS ${stdlib_flag})
 
+if(COMPILER_RT_USE_LLVM_UNWINDER)
+  # TODO: set --unwindlib=none after https://reviews.llvm.org/D115674 lands.
+  if (COMPILER_RT_ENABLE_STATIC_UNWINDER)
+    set(unwinder_target unwind_static)
+  else()
+    set(unwinder_target unwind_shared)
+  endif()
+  list(APPEND SANITIZER_CXX_ABI_LIBRARIES "$<$<TARGET_EXISTS:${unwind_target}>:$<TARGET_LINKER_FILE:${unwind_target}>>")
+endif()
+
 macro(append_libcxx_libs var)
   if (${var}_INTREE)
+    # If we're linking directly against the libunwind that we're building
+    # in the same invocation, don't try to link in the toolchain's
+    # default libunwind (which may be missing still).
+    append_list_if(CXX_SUPPORTS_UNWINDLIB_NONE_FLAG --unwindlib=none SANITIZER_COMMON_LINK_FLAGS)
+
     if (SANITIZER_USE_STATIC_LLVM_UNWINDER AND (TARGET unwind_static OR HAVE_LIBUNWIND))
       list(APPEND ${var}_LIBRARIES unwind_static)
     elseif (TARGET unwind_shared OR HAVE_LIBUNWIND)


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