Respect llvm.used in Internalize.

The language reference says that:

"If a symbol appears in the @llvm.used list, then the compiler,
assembler, and linker are required to treat the symbol as if there is
a reference to the symbol that it cannot see"

Since even the linker cannot see the reference, we must assume that
the reference can be using the symbol table. For example, a user can add
__attribute__((used)) to a debug helper function like dump and use it from
a debugger.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187103 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 0 deletions

diff --git a/include/llvm/Transforms/Utils/ModuleUtils.h b/include/llvm/Transforms/Utils/ModuleUtils.h
index bb7fc06..98a19ed 100644
--- a/include/llvm/Transforms/Utils/ModuleUtils.h
+++ b/include/llvm/Transforms/Utils/ModuleUtils.h
@@ -18,6 +18,9 @@ namespace llvm {
 
 class Module;
 class Function;
+class GlobalValue;
+class GlobalVariable;
+template <class PtrType, unsigned SmallSize> class SmallPtrSet;
 
 /// Append F to the list of global ctors of module M with the given Priority.
 /// This wraps the function in the appropriate structure and stores it along
@@ -28,6 +31,11 @@ void appendToGlobalCtors(Module &M, Function *F, int Priority);
 /// Same as appendToGlobalCtors(), but for global dtors.
 void appendToGlobalDtors(Module &M, Function *F, int Priority);
 
+/// \brief Given "llvm.used" or "llvm.compiler.used" as a global name, collect
+/// the initializer elements of that global in Set and return the global itself.
+GlobalVariable *collectUsedGlobalVariables(Module &M,
+                                           SmallPtrSet<GlobalValue *, 8> &Set,
+                                           bool CompilerUsed);
 } // End llvm namespace
 
 #endif //  LLVM_TRANSFORMS_UTILS_MODULEUTILS_H