[asan] Restore ODR-violation detection on vtables

[vitalybuka]

Summary

unnamed_addr is still useful for detecting of ODR violations on vtables

Still unnamed_addr with lld and --icf=safe or --icf=all can trigger false
reports which can be avoided with --icf=none or by using private aliases
with -fsanitize-address-use-odr-indicator

[vitalybuka]

renamed classes

[eugenis]

LGTM
Does it mean that either --icf=none or odr-indicators must be used to avoid false positives?

[vitalybuka]

Done

compiler-rt/test/asan/TestCases/Linux/odr-vtable.cc

+// RUN: %clangxx_asan -fno-rtti -DBUILD_SO1 -fPIC -shared %s -o %t1.so
+// RUN: %clangxx_asan -fno-rtti -DBUILD_SO2 -fPIC -shared %s -o %t2.so
+// RUN: %clangxx_asan -fno-rtti %t1.so %t2.so %s -Wl,-R. -o %t
+// RUN: %env_asan_opts=fast_unwind_on_malloc=0:detect_odr_violation=2 not %run %t 2>&1 | FileCheck %s
+
+struct XYZ {
+  virtual void foo();
+};
+
+#if defined(BUILD_SO1)
+
+void XYZ::foo() {}
+
+#elif defined(BUILD_SO2)
+
+void XYZ::foo() {}
+
+#else
+
+int main() {}
+
+#endif
+
+// CHECK: AddressSanitizer: odr-violation
+// CHECK-NEXT: 'vtable for XYZ'
+// CHECK-NEXT: 'vtable for XYZ'

llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp

if (CanUsePrivateAliases && UsePrivateAlias) {
       // Create local alias for NewGlobal to avoid crash on ODR between
       // instrumented and non-instrumented libraries.
       InstrumentedGlobal =
           GlobalAlias::create(GlobalValue::PrivateLinkage, "", NewGlobal);
     }
 
     // ODR check is not useful for the following, but we see false reports
     // caused by linker optimizations.
-    if (NewGlobal->hasLocalLinkage() || NewGlobal->hasGlobalUnnamedAddr() ||
-        NewGlobal->hasLinkOnceODRLinkage() || NewGlobal->hasWeakODRLinkage()) {
+    if (NewGlobal->hasLocalLinkage() || NewGlobal->hasLinkOnceODRLinkage() ||
+        NewGlobal->hasWeakODRLinkage()) {
       ODRIndicator = ConstantExpr::getIntToPtr(ConstantInt::get(IntptrTy, -1),
                                                IRB.getInt8PtrTy());
     } else if (UseOdrIndicator) {
       // 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()),

llvm/test/Instrumentation/AddressSanitizer/odr-check-ignore.ll

 ; RUN: opt < %s -asan -asan-module -S | FileCheck %s 
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 @a = global [2 x i32] zeroinitializer, align 4
 @b = private global [2 x i32] zeroinitializer, align 4
 @c = internal global [2 x i32] zeroinitializer, align 4
 @d = unnamed_addr global [2 x i32] zeroinitializer, align 4
 
 ; CHECK: @__asan_global_a = private global { i64, i64, i64, i64, i64, i64, i64, i64 } { i64 ptrtoint ({ [2 x i32], [56 x i8] }* @a to i64), i64 8, i64 64, i64 ptrtoint ([2 x i8]* @___asan_gen_.1 to i64), i64 ptrtoint ([8 x i8]* @___asan_gen_ to i64), i64 0, i64 0, i64 0 }
 
 ; CHECK: @__asan_global_b = private global { i64, i64, i64, i64, i64, i64, i64, i64 } { i64 ptrtoint ({ [2 x i32], [56 x i8] }* @b to i64), i64 8, i64 64, i64 ptrtoint ([2 x i8]* @___asan_gen_.2 to i64), i64 ptrtoint ([8 x i8]* @___asan_gen_ to i64), i64 0, i64 0, i64 -1 }
 
 ; CHECK: @__asan_global_c = private global { i64, i64, i64, i64, i64, i64, i64, i64 } { i64 ptrtoint ({ [2 x i32], [56 x i8] }* @c to i64), i64 8, i64 64, i64 ptrtoint ([2 x i8]* @___asan_gen_.3 to i64), i64 ptrtoint ([8 x i8]* @___asan_gen_ to i64), i64 0, i64 0, i64 -1 }
 
-; CHECK: @__asan_global_d = private global { i64, i64, i64, i64, i64, i64, i64, i64 } { i64 ptrtoint ({ [2 x i32], [56 x i8] }* @d to i64), i64 8, i64 64, i64 ptrtoint ([2 x i8]* @___asan_gen_.4 to i64), i64 ptrtoint ([8 x i8]* @___asan_gen_ to i64), i64 0, i64 0, i64 -1 }
+; CHECK: @__asan_global_d = private global { i64, i64, i64, i64, i64, i64, i64, i64 } { i64 ptrtoint ({ [2 x i32], [56 x i8] }* @d to i64), i64 8, i64 64, i64 ptrtoint ([2 x i8]* @___asan_gen_.4 to i64), i64 ptrtoint ([8 x i8]* @___asan_gen_ to i64), i64 0, i64 0, i64 0 }