[LLVMdev] ICE in LLVM GCC4 Front End

[Bill Wendling]

[Reposted from llvm-bugs mailing list. Also has an updated, hopefully  
better, patch associated with it.]

Hi,

The following program causes the LLVM GCC4 front end to ICE:

struct A {
   virtual ~A();
};

template <typename Ty>
struct B : public A {
   ~B () { delete [] val; }
private:
     Ty* val;
};

template <typename Ty>
struct C : public A {
   C ();
   ~C ();
};

template <typename Ty>
struct D : public A {
     D () {}
   private:
     B<C<Ty> > blocks;
};

template class D<double>;

I'm far from an expert on this area of the code base, so I'm  
submitting this as a proposed fix:

Index: gcc/llvm-convert.cpp
===================================================================
--- gcc/llvm-convert.cpp        (revision 166)
+++ gcc/llvm-convert.cpp        (working copy)
@@ -2202,18 +2202,23 @@

      // Figure out how large the element pointed to is.
      const Type *ElTy = cast<PointerType>(LHS->getType())- 
 >getElementType();
-    int64_t EltSize = TD.getTypeSize(ElTy);
+
+    if (!ElTy->isAbstract()) {
+      // We can only get the type size (and thus convert to using a  
GEP instr)
+      // if the type isn't abstract
+      int64_t EltSize = TD.getTypeSize(ElTy);

-    // If EltSize exactly divides Offset, then we know that we can  
turn this
-    // into a getelementptr instruction.
-    int64_t EltOffset = Offset/EltSize;
-    if (EltOffset*EltSize == Offset) {
-      // If this is a subtract, we want to step backwards.
-      if (Opc == Instruction::Sub)
-        EltOffset = -EltOffset;
-      Constant *C = ConstantSInt::get(Type::LongTy, EltOffset);
-      Value *V = new GetElementPtrInst(LHS, C, "tmp", CurBB);
-      return CastToType(V, TREE_TYPE(exp));
+      // If EltSize exactly divides Offset, then we know that we can  
turn
+      // this into a getelementptr instruction.
+      int64_t EltOffset = Offset/EltSize;
+      if (EltOffset*EltSize == Offset) {
+        // If this is a subtract, we want to step backwards.
+        if (Opc == Instruction::Sub)
+          EltOffset = -EltOffset;
+        Constant *C = ConstantSInt::get(Type::LongTy, EltOffset);
+        Value *V = new GetElementPtrInst(LHS, C, "tmp", CurBB);
+        return CastToType(V, TREE_TYPE(exp));
+      }
      }
    }