[compiler-rt] Allow sanitizers to be compiled for windows with clang

[fjricci]

Summary

A few small changes required to permit building the sanitizers
with Clang instead of only with MSVC.

[timurrrr]

I don't actively work on ASan anymore.

Did you make sure all the ASan tests pass when the RTL is complied this way? I remember there was *some* reason why this wasn't enabled before. It is possible that the last time it was evaluated was a long time ago, when Clang/Win wasn't mature enough though.

[rnk]

This already works if you use clang-cl. Is this about making things work in a mingw environment?

[fjricci]

While the current form works for clang-cl, this change is necessary if you want to use the gcc-compatible driver in clang when targeting windows.

[rnk]

cmake/config-ix.cmake

418 ↗

(On Diff #69882)

I think what we really want to say here is "we support the MS CRT, not the mingw CRT". The check as written will enable building asan for mingw, and that would break their builds. I don't know how to ask that CRT question in cmake though...

[fjricci]

I could add a check for AND NOT MINGW AND NOT CYGWIN

[compnerd]

cmake/config-ix.cmake

418 ↗

(On Diff #69882)

The only way that I can see how to phrase that is to use the COMPILER_RT_TARGET and rip the environment from that. The gnu and cygnus environments are the one with their own CRT and msvc and itanium use the Microsoft CRT.

[fjricci]

Make sure to exclude mingw and cygwin

[rnk]

Minor thing, otherwise let's do it.

lib/asan/CMakeLists.txt

217 ↗

(On Diff #70581)

I think clang-cl identifies as clang and MSVC is true, so you want to do if (MSVC) first.

[fjricci]

Fixed the if/elseif order and committed.

compiler-rt/trunk/cmake/config-ix.cmake

 
 set(ALL_SANITIZERS asan;dfsan;msan;tsan;safestack;cfi;esan;scudo)
 set(COMPILER_RT_SANITIZERS_TO_BUILD ${ALL_SANITIZERS} CACHE STRING
     "sanitizers to build if supported on the target (all;${ALL_SANITIZERS})")
 list_replace(COMPILER_RT_SANITIZERS_TO_BUILD all "${ALL_SANITIZERS}")
 
 if (SANITIZER_COMMON_SUPPORTED_ARCH AND NOT LLVM_USE_SANITIZER AND
     (OS_NAME MATCHES "Android|Darwin|Linux|FreeBSD" OR
-    (OS_NAME MATCHES "Windows" AND MSVC)))
+    (OS_NAME MATCHES "Windows" AND (NOT MINGW AND NOT CYGWIN))))
   set(COMPILER_RT_HAS_SANITIZER_COMMON TRUE)
 else()
   set(COMPILER_RT_HAS_SANITIZER_COMMON FALSE)
 endif()
 
 if (COMPILER_RT_HAS_SANITIZER_COMMON)
   set(COMPILER_RT_HAS_INTERCEPTION TRUE)
 else()

compiler-rt/trunk/lib/asan/CMakeLists.txt

if (WIN32)
       add_compiler_rt_runtime(clang_rt.asan_dll_thunk
         STATIC
         ARCHS ${arch}
         SOURCES asan_win_dll_thunk.cc
                 $<TARGET_OBJECTS:RTInterception.${arch}>
         CFLAGS ${ASAN_CFLAGS} -DASAN_DLL_THUNK
         DEFS ${ASAN_COMMON_DEFINITIONS}
         PARENT_TARGET asan)
+
+      set(DYNAMIC_RUNTIME_THUNK_CFLAGS "-DASAN_DYNAMIC_RUNTIME_THUNK")
+      if(MSVC)
+        list(APPEND DYNAMIC_RUNTIME_THUNK_CFLAGS "-Zl")
+      elseif(CMAKE_C_COMPILER_ID MATCHES Clang)
+        list(APPEND DYNAMIC_RUNTIME_THUNK_CFLAGS "-nodefaultlibs")
+      endif()
+
       add_compiler_rt_runtime(clang_rt.asan_dynamic_runtime_thunk
         STATIC
         ARCHS ${arch}
         SOURCES asan_win_dynamic_runtime_thunk.cc
-        CFLAGS ${ASAN_CFLAGS} -DASAN_DYNAMIC_RUNTIME_THUNK -Zl
+        CFLAGS ${ASAN_CFLAGS} ${DYNAMIC_RUNTIME_THUNK_CFLAGS}
         DEFS ${ASAN_COMMON_DEFINITIONS}
         PARENT_TARGET asan)
     endif()
   endforeach()
 endif()
 
 add_compiler_rt_resource_file(asan_blacklist asan_blacklist.txt asan)
 
 add_subdirectory(scripts)
 
 if(COMPILER_RT_INCLUDE_TESTS)
   add_subdirectory(tests)
 endif()