1 files changed, 44 insertions, 6 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index a3788af3de7..2f404fe1626 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -96,7 +96,7 @@ static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
 static const char *const kAsanInitName = "__asan_init";
 static const char *const kAsanVersionCheckName =
-    "__asan_version_mismatch_check_v6";
+    "__asan_version_mismatch_check_v7";
 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
@@ -104,6 +104,7 @@ static const int kMaxAsanStackMallocSizeClass = 10;
 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
 static const char *const kAsanGenPrefix = "__asan_gen_";
+static const char *const kODRGenPrefix = "__odr_asan_gen_";
 static const char *const kSanCovGenPrefix = "__sancov_gen_";
 static const char *const kAsanPoisonStackMemoryName =
     "__asan_poison_stack_memory";
@@ -229,6 +230,12 @@ static cl::opt<uint32_t> ClForceExperiment(
     cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
     cl::init(0));
 
+static cl::opt<bool>
+    ClUsePrivateAliasForGlobals("asan-use-private-alias",
+                                cl::desc("Use private aliases for global"
+                                         " variables"),
+                                cl::Hidden, cl::init(false));
+
 // Debug flags.
 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
                             cl::init(0));
@@ -823,7 +830,8 @@ static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
 
 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
   return G->getName().find(kAsanGenPrefix) == 0 ||
-         G->getName().find(kSanCovGenPrefix) == 0;
+         G->getName().find(kSanCovGenPrefix) == 0 ||
+         G->getName().find(kODRGenPrefix) == 0;
 }
 
 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
@@ -1321,10 +1329,11 @@ bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
   //   const char *module_name;
   //   size_t has_dynamic_init;
   //   void *source_location;
+  //   size_t odr_indicator;
   // We initialize an array of such structures and pass it to a run-time call.
   StructType *GlobalStructTy =
       StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
-                      IntptrTy, IntptrTy, nullptr);
+                      IntptrTy, IntptrTy, IntptrTy, nullptr);
   SmallVector<Constant *, 16> Initializers(n);
 
   bool HasDynamicallyInitializedGlobals = false;
@@ -1340,10 +1349,11 @@ bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
     GlobalVariable *G = GlobalsToChange[i];
 
     auto MD = GlobalsMD.get(G);
+    StringRef NameForGlobal = G->getName();
     // Create string holding the global name (use global name from metadata
     // if it's available, otherwise just write the name of global variable).
     GlobalVariable *Name = createPrivateGlobalForString(
-        M, MD.Name.empty() ? G->getName() : MD.Name,
+        M, MD.Name.empty() ? NameForGlobal : MD.Name,
         /*AllowMerging*/ true);
 
     Type *Ty = G->getValueType();
@@ -1391,13 +1401,41 @@ bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
       SourceLoc = ConstantInt::get(IntptrTy, 0);
     }
 
+    Constant *ODRIndicator = ConstantExpr::getNullValue(IRB.getInt8PtrTy());
+    GlobalValue *InstrumentedGlobal = NewGlobal;
+
+    bool CanUsePrivateAliases = TargetTriple.isOSBinFormatELF();
+    if (CanUsePrivateAliases && ClUsePrivateAliasForGlobals) {
+      // Create local alias for NewGlobal to avoid crash on ODR between
+      // instrumented and non-instrumented libraries.
+      auto *GA = GlobalAlias::create(GlobalValue::InternalLinkage,
+                                     NameForGlobal + M.getName(), NewGlobal);
+
+      // With local aliases, we need to provide another externally visible
+      // symbol __odr_asan_XXX to detect ODR violation.
+      auto *ODRIndicatorSym =
+          new GlobalVariable(M, IRB.getInt8Ty(), false, Linkage,
+                             Constant::getNullValue(IRB.getInt8Ty()),
+                             kODRGenPrefix + NameForGlobal, nullptr,
+                             NewGlobal->getThreadLocalMode());
+
+      // Set meaningful attributes for indicator symbol.
+      ODRIndicatorSym->setVisibility(NewGlobal->getVisibility());
+      ODRIndicatorSym->setDLLStorageClass(NewGlobal->getDLLStorageClass());
+      ODRIndicatorSym->setAlignment(1);
+      ODRIndicator = ODRIndicatorSym;
+      InstrumentedGlobal = GA;
+    }
+
     Initializers[i] = ConstantStruct::get(
-        GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
+        GlobalStructTy,
+        ConstantExpr::getPointerCast(InstrumentedGlobal, IntptrTy),
         ConstantInt::get(IntptrTy, SizeInBytes),
         ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
         ConstantExpr::getPointerCast(Name, IntptrTy),
         ConstantExpr::getPointerCast(ModuleName, IntptrTy),
-        ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, nullptr);
+        ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc,
+        ConstantExpr::getPointerCast(ODRIndicator, IntptrTy), nullptr);
 
     if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;