When a function takes a variable number of pointer arguments, with a zero

pointer marking the end of the list, the zero *must* be cast to the pointer
type.  An un-cast zero is a 32-bit int, and at least on x86_64, gcc will
not extend the zero to 64 bits, thus allowing the upper 32 bits to be
random junk.

The new END_WITH_NULL macro may be used to annotate a such a function
so that GCC (version 4 or newer) will detect the use of un-casted zero
at compile time.

llvm-svn: 23888

1 files changed, 2 insertions, 1 deletions

diff --git a/llvm/examples/Fibonacci/fibonacci.cpp b/llvm/examples/Fibonacci/fibonacci.cpp
index af17d094c30..e9d0136f4f4 100644
--- a/llvm/examples/Fibonacci/fibonacci.cpp
+++ b/llvm/examples/Fibonacci/fibonacci.cpp
@@ -37,7 +37,8 @@ using namespace llvm;
 static Function *CreateFibFunction(Module *M) {
   // Create the fib function and insert it into module M.  This function is said
   // to return an int and take an int parameter.
-  Function *FibF = M->getOrInsertFunction("fib", Type::IntTy, Type::IntTy, 0);
+  Function *FibF = M->getOrInsertFunction("fib", Type::IntTy, Type::IntTy,
+                                          (Type *)0);
 
   // Add a basic block to the function.
   BasicBlock *BB = new BasicBlock("EntryBlock", FibF);