[compiler-rt] Fix ASan's Noinst unit tests

[kubamracek]

Summary

I noticed that on OS X, we currently skip all "Noinst" unit tests, see http://lab.llvm.org:8080/green/job/clang-stage1-cmake-RA_check/1384/consoleFull and search for "Asan-i386-inline-Noinst-Test" (they're not being run at all). The reason is that in MaybeReexec() we always try to set DYLD_INSERT_LIBRARIES to the module where we find the __asan_init symbol. However, the non-instrumented unit tests link the runtime statically, so this symbol is in the executable itself.

This was probably caused when we removed the "allow_reexec" flag. This patch adds a check into MaybeReexec such that if the module that contains the __asan_init symbol is not a dylib, we will not try to re-execute at all. This should only affect the statically-linked unit tests, all other uses on OS X should use the dynamic library.

[samsonov]

I think we should fix the tests instead: build dynamic version of RTAsanTest library on OS X, and link with it dynamically.

[glider]

I don't think it's a good idea to make a dynamic library that actually isn't a runtime library and use it as a runtime library.
Also, to create this new dynamic library we'll have to expose additional interface functions which the noinst tests are supposed to test.

Maybe we can just add an internal function that disables re-execution?

[kubamracek]

Updating the patch to use an internal function that disable re-execution.

[samsonov]

LGTM

[kubamracek]

Landed in r228740.

lib/asan/asan_internal.h

 // asan_linux.cc / asan_mac.cc / asan_win.cc
 void *AsanDoesNotSupportStaticLinkage();
 void AsanCheckDynamicRTPrereqs();
 void AsanCheckIncompatibleRT();
 
 void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp);
 void AsanOnSIGSEGV(int, void *siginfo, void *context);
 
+void DisableReexec();
 void MaybeReexec();
 void ReadContextStack(void *context, uptr *stack, uptr *ssize);
 void AsanPlatformThreadInit();
 void StopInitOrderChecking();
 
 // Wrapper for TLS/TSD.
 void AsanTSDInit(void (*destructor)(void *tsd));
 void *AsanTSDGet();

lib/asan/asan_linux.cc

 // FIXME: perhaps also store abi version here?
 extern "C" {
 SANITIZER_INTERFACE_ATTRIBUTE
 asan_rt_version_t  __asan_rt_version;
 }
 
 namespace __asan {
 
+void DisableReexec() {
+  // No need to re-exec on Linux.
+}
+
 void MaybeReexec() {
   // No need to re-exec on Linux.
 }
 
 void *AsanDoesNotSupportStaticLinkage() {
   // This will fail to link with -static.
   return &_DYNAMIC;  // defined in link.h
 }

lib/asan/asan_mac.cc

if (len > name_len) {
           } while (*del++);
         }
       }
     }
     environ++;
   }
 }
 
+static bool reexec_disabled = false;
+
+void DisableReexec() {
+  reexec_disabled = true;
+}
+
 void MaybeReexec() {
+  if (reexec_disabled) return;
+
   // Make sure the dynamic ASan runtime library is preloaded so that the
   // wrappers work. If it is not, set DYLD_INSERT_LIBRARIES and re-exec
   // ourselves.
   Dl_info info;
   CHECK(dladdr((void*)((uptr)__asan_init), &info));
   char *dyld_insert_libraries =
       const_cast<char*>(GetEnv(kDyldInsertLibraries));
   uptr old_env_len = dyld_insert_libraries ?

lib/asan/asan_win.cc

void AsanTSDSet(void *tsd) {
   CHECK(tsd_key_inited);
   fake_tsd = tsd;
 }
 
 void PlatformTSDDtor(void *tsd) {
   AsanThread::TSDDtor(tsd);
 }
 // ---------------------- Various stuff ---------------- {{{1
+void DisableReexec() {
+  // No need to re-exec on Windows.
+}
+
 void MaybeReexec() {
   // No need to re-exec on Windows.
 }
 
 void *AsanDoesNotSupportStaticLinkage() {
 #if defined(_DEBUG)
 #error Please build the runtime with a non-debug CRT: /MD or /MT
 #endif

lib/asan/tests/asan_noinst_test.cc

 
 // ATTENTION!
 // Please don't call intercepted functions (including malloc() and friends)
 // in this test. The static runtime library is linked explicitly (without
 // -fsanitize=address), thus the interceptors do not work correctly on OS X.
 
 // Make sure __asan_init is called before any test case is run.
 struct AsanInitCaller {
-  AsanInitCaller() { __asan_init(); }
+  AsanInitCaller() {
+    __asan::DisableReexec();
+    __asan_init();
+  }
 };
 static AsanInitCaller asan_init_caller;
 
 TEST(AddressSanitizer, InternalSimpleDeathTest) {
   EXPECT_DEATH(exit(1), "");
 }
 
 static void MallocStress(size_t n) {