Fix for PR7040: Don't try to compute the LLVM type for a function where it

isn't possible to compute.

This patch is mostly refactoring; the key change is the addition of the code
starting with the comment, "Check whether the function has a computable LLVM
signature."  The solution here is essentially the same as the way the
vtable code handles such functions.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@105151 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 38 insertions, 0 deletions

diff --git a/lib/CodeGen/CGCXX.cpp b/lib/CodeGen/CGCXX.cpp
index 525877903e..60f1f6f7eb 100644
--- a/lib/CodeGen/CGCXX.cpp
+++ b/lib/CodeGen/CGCXX.cpp
@@ -304,6 +304,44 @@ void CodeGenModule::getMangledCXXDtorName(MangleBuffer &Name,
   getMangleContext().mangleCXXDtor(D, Type, Name.getBuffer());
 }
 
+llvm::Constant *
+CodeGenModule::GetCXXMemberFunctionPointerValue(const CXXMethodDecl *MD) {
+  assert(MD->isInstance() && "Member function must not be static!");
+    
+  MD = MD->getCanonicalDecl();
+
+  const llvm::Type *PtrDiffTy = Types.ConvertType(Context.getPointerDiffType());
+
+  // Get the function pointer (or index if this is a virtual function).
+  if (MD->isVirtual()) {
+    uint64_t Index = VTables.getMethodVTableIndex(MD);
+
+    // FIXME: We shouldn't use / 8 here.
+    uint64_t PointerWidthInBytes = Context.Target.getPointerWidth(0) / 8;
+
+    // Itanium C++ ABI 2.3:
+    //   For a non-virtual function, this field is a simple function pointer. 
+    //   For a virtual function, it is 1 plus the virtual table offset 
+    //   (in bytes) of the function, represented as a ptrdiff_t. 
+    return llvm::ConstantInt::get(PtrDiffTy, (Index * PointerWidthInBytes) + 1);
+  }
+
+  const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();
+  const llvm::Type *Ty;
+  // Check whether the function has a computable LLVM signature.
+  if (!CodeGenTypes::VerifyFuncTypeComplete(FPT)) {
+    // The function has a computable LLVM signature; use the correct type.
+    Ty = Types.GetFunctionType(Types.getFunctionInfo(MD), FPT->isVariadic());
+  } else {
+    // Use an arbitrary non-function type to tell GetAddrOfFunction that the
+    // function type is incomplete.
+    Ty = PtrDiffTy;
+  }
+
+  llvm::Constant *FuncPtr = GetAddrOfFunction(MD, Ty);
+  return llvm::ConstantExpr::getPtrToInt(FuncPtr, PtrDiffTy);
+}
+
 static llvm::Value *BuildVirtualCall(CodeGenFunction &CGF, uint64_t VTableIndex, 
                                      llvm::Value *This, const llvm::Type *Ty) {
   Ty = Ty->getPointerTo()->getPointerTo()->getPointerTo();