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.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23888 91177308-0d34-0410-b5e6-96231b3b80d8

Makefile.rules

@@ -221,7 +221,7 @@ else
   endif
 endif
 
-CXX.Flags += $(CXXFLAGS)
+CXX.Flags += $(CXXFLAGS) -Wformat
 C.Flags   += $(CFLAGS)
 CPP.Flags += $(CPPFLAGS)
 LD.Flags  += $(LDFLAGS)

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);

examples/HowToUseJIT/HowToUseJIT.cpp

@@ -51,7 +51,8 @@ int main() {
   // Create the add1 function entry and insert this entry into module M.  The
   // function will have a return type of "int" and take an argument of "int".
   // The '0' terminates the list of argument types.
-  Function *Add1F = M->getOrInsertFunction("add1", Type::IntTy, Type::IntTy, 0);
+  Function *Add1F = M->getOrInsertFunction("add1", Type::IntTy, Type::IntTy,
+                                           (Type *)0);
 
   // Add a basic block to the function. As before, it automatically inserts
   // because of the last argument.
@@ -76,7 +77,7 @@ int main() {
 
   // Now we going to create function `foo', which returns an int and takes no
   // arguments.
-  Function *FooF = M->getOrInsertFunction("foo", Type::IntTy, 0);
+  Function *FooF = M->getOrInsertFunction("foo", Type::IntTy, (Type *)0);
 
   // Add a basic block to the FooF function.
   BB = new BasicBlock("EntryBlock", FooF);

examples/ParallelJIT/ParallelJIT.cpp

@@ -33,7 +33,8 @@ static Function* createAdd1(Module* M)
   // Create the add1 function entry and insert this entry into module M.  The
   // function will have a return type of "int" and take an argument of "int".
   // The '0' terminates the list of argument types.
-  Function *Add1F = M->getOrInsertFunction("add1", Type::IntTy, Type::IntTy, 0);
+  Function *Add1F = M->getOrInsertFunction("add1", Type::IntTy, Type::IntTy,
+                                           (Type *)0);
 
   // Add a basic block to the function. As before, it automatically inserts
   // because of the last argument.
@@ -61,7 +62,8 @@ 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);

include/llvm/Module.h

@@ -22,6 +22,7 @@
 #include "llvm/Function.h"
 #include "llvm/GlobalVariable.h"
 #include "llvm/ADT/SetVector.h"
+#include "llvm/Support/DataTypes.h"
 
 namespace llvm {
 
@@ -111,7 +112,8 @@ class Module {
   /// table.  If it does not exist, add a prototype for the function and return
   /// it.  This version of the method takes a null terminated list of function
   /// arguments, which makes it easier for clients to use.
-  Function *getOrInsertFunction(const std::string &Name, const Type *RetTy,...);
+  Function *getOrInsertFunction(const std::string &Name, const Type *RetTy,...)
+    END_WITH_NULL;
 
   /// getFunction - Look up the specified function in the module symbol table.
   /// If it does not exist, return null.

include/llvm/Support/CommandLine.h

@@ -21,6 +21,7 @@
 #define LLVM_SUPPORT_COMMANDLINE_H
 
 #include "llvm/Support/type_traits.h"
+#include "llvm/Support/DataTypes.h"
 #include <string>
 #include <vector>
 #include <utility>
@@ -335,7 +336,7 @@ class ValuesClass {
 
 template<class DataType>
 ValuesClass<DataType> values(const char *Arg, DataType Val, const char *Desc,
-                             ...) {
+                             ...) END_WITH_NULL {
     va_list ValueArgs;
     va_start(ValueArgs, Desc);
     ValuesClass<DataType> Vals(Arg, Val, Desc, ValueArgs);

include/llvm/Support/DataTypes.h.in

@@ -98,4 +98,10 @@ typedef signed int ssize_t;
 # define UINT64_MAX 0xffffffffffffffffULL
 #endif
 
+#if __GNUC__ > 3
+#define END_WITH_NULL __attribute__((sentinel))
+#else
+#define END_WITH_NULL
+#endif
+
 #endif  /* SUPPORT_DATATYPES_H */