r258596 - [cfi] Do not emit bit set entry for available_externally vtables.

[Evgeniy Stepanov via cfe-commits]

Author: eugenis
Date: Fri Jan 22 19:20:18 2016
New Revision: 258596

URL: http://llvm.org/viewvc/llvm-project?rev=258596&view=rev
Log:
[cfi] Do not emit bit set entry for available_externally vtables.

In the Itanium ABI, vtable may be emitted speculatively as an
available_externally global. Such vtable may not be present at the
link time and should not have a corresponding CFI bit set entry.

Added:
    cfe/trunk/test/CodeGenCXX/cfi-speculative-vtable.cpp
Modified:
    cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp

Modified: cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp?rev=258596&r1=258595&r2=258596&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp (original)
+++ cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp Fri Jan 22 19:20:18 2016
@@ -1496,7 +1496,8 @@ void ItaniumCXXABI::emitVTableDefinition
       DC->getParent()->isTranslationUnit())
     EmitFundamentalRTTIDescriptors();
 
-  CGM.EmitVTableBitSetEntries(VTable, VTLayout);
+  if (!VTable->isDeclarationForLinker())
+    CGM.EmitVTableBitSetEntries(VTable, VTLayout);
 }
 
 bool ItaniumCXXABI::isVirtualOffsetNeededForVTableField(

Added: cfe/trunk/test/CodeGenCXX/cfi-speculative-vtable.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/cfi-speculative-vtable.cpp?rev=258596&view=auto
==============================================================================
--- cfe/trunk/test/CodeGenCXX/cfi-speculative-vtable.cpp (added)
+++ cfe/trunk/test/CodeGenCXX/cfi-speculative-vtable.cpp Fri Jan 22 19:20:18 2016
@@ -0,0 +1,14 @@
+// Test that we don't emit a bit set entry for a speculative (available_externally) vtable.
+// This does not happen in the Microsoft ABI.
+// RUN: %clang_cc1 -triple x86_64-unknown-linux -O1 -fsanitize=cfi-vcall -fsanitize-trap=cfi-vcall -emit-llvm -o - %s | FileCheck  %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux -O1 -fsanitize=cfi-vcall -fsanitize-trap=cfi-vcall -fsanitize-cfi-cross-dso -emit-llvm -o - %s | FileCheck  %s
+
+class A {
+ public:
+  virtual ~A();
+};
+
+A a;
+
+// CHECK: @_ZTV1A ={{.*}} available_externally
+// CHECK-NOT: !{{.*}} = !{!{{.*}}, [4 x i8*]* @_ZTV1A, i64 16}