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
diff --git a/llvm/lib/Transforms/Scalar/LowerGC.cpp b/llvm/lib/Transforms/Scalar/LowerGC.cpp
index 345fafb..e346c23 100644
--- a/llvm/lib/Transforms/Scalar/LowerGC.cpp
+++ b/llvm/lib/Transforms/Scalar/LowerGC.cpp
@@ -109,10 +109,11 @@
// If the program is using read/write barriers, find the implementations of
// them from the GC runtime library.
if (GCReadInt) // Make: sbyte* %llvm_gc_read(sbyte**)
- GCRead = M.getOrInsertFunction("llvm_gc_read", VoidPtr, VoidPtr, VoidPtrPtr, 0);
+ GCRead = M.getOrInsertFunction("llvm_gc_read", VoidPtr, VoidPtr, VoidPtrPtr,
+ (Type *)0);
if (GCWriteInt) // Make: void %llvm_gc_write(sbyte*, sbyte**)
GCWrite = M.getOrInsertFunction("llvm_gc_write", Type::VoidTy,
- VoidPtr, VoidPtr, VoidPtrPtr, 0);
+ VoidPtr, VoidPtr, VoidPtrPtr, (Type *)0);
// If the program has GC roots, get or create the global root list.
if (GCRootInt) {