[llvm-commits] [llvm] r170658 - /llvm/trunk/lib/VMCore/Value.cpp

[Richard Smith]

Author: rsmith
Date: Wed Dec 19 22:11:02 2012
New Revision: 170658

URL: http://llvm.org/viewvc/llvm-project?rev=170658&view=rev
Log:
Don't use isa<CallInst>(this) in the constructor for CallInst's base class.
This has undefined behavior, because the classof implementation attempts to
access parts of the not-yet-constructed derived class. Found by clang
-fsanitize=vptr.

Modified:
    llvm/trunk/lib/VMCore/Value.cpp

Modified: llvm/trunk/lib/VMCore/Value.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/VMCore/Value.cpp?rev=170658&r1=170657&r2=170658&view=diff
==============================================================================
--- llvm/trunk/lib/VMCore/Value.cpp (original)
+++ llvm/trunk/lib/VMCore/Value.cpp Wed Dec 19 22:11:02 2012
@@ -46,10 +46,13 @@
     SubclassOptionalData(0), SubclassData(0), VTy((Type*)checkType(ty)),
     UseList(0), Name(0) {
   // FIXME: Why isn't this in the subclass gunk??
-  if (isa<CallInst>(this) || isa<InvokeInst>(this))
+  // Note, we cannot call isa<CallInst> before the CallInst has been
+  // constructed.
+  if (SubclassID == Instruction::Call || SubclassID == Instruction::Invoke)
     assert((VTy->isFirstClassType() || VTy->isVoidTy() || VTy->isStructTy()) &&
            "invalid CallInst type!");
-  else if (!isa<Constant>(this) && !isa<BasicBlock>(this))
+  else if (SubclassID != BasicBlockVal &&
+           (SubclassID < ConstantFirstVal || SubclassID > ConstantLastVal))
     assert((VTy->isFirstClassType() || VTy->isVoidTy()) &&
            "Cannot create non-first-class values except for constants!");
 }