CodeGen: Use PLT relocations for relative references to unnamed_addr functions.

The relative vtable ABI (PR26723) needs PLT relocations to refer to virtual
functions defined in other DSOs. The unnamed_addr attribute means that the
function's address is not significant, so we're allowed to substitute it
with the address of a PLT entry.

Also includes a bonus feature: addends for COFF image-relative references.

Differential Revision: http://reviews.llvm.org/D17938

llvm-svn: 267211

1 files changed, 6 insertions, 2 deletions

diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index d87a0800262..ebe8a27999f 100644
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -231,10 +231,12 @@ Constant *FoldBitCast(Constant *C, Type *DestTy, const DataLayout &DL) {
   return ConstantVector::get(Result);
 }
 
+} // end anonymous namespace
+
 /// If this constant is a constant offset from a global, return the global and
 /// the constant. Because of constantexprs, this function is recursive.
-bool IsConstantOffsetFromGlobal(Constant *C, GlobalValue *&GV, APInt &Offset,
-                                const DataLayout &DL) {
+bool llvm::IsConstantOffsetFromGlobal(Constant *C, GlobalValue *&GV,
+                                      APInt &Offset, const DataLayout &DL) {
   // Trivial case, constant is the global.
   if ((GV = dyn_cast<GlobalValue>(C))) {
     unsigned BitWidth = DL.getPointerTypeSizeInBits(GV->getType());
@@ -271,6 +273,8 @@ bool IsConstantOffsetFromGlobal(Constant *C, GlobalValue *&GV, APInt &Offset,
   return true;
 }
 
+namespace {
+
 /// Recursive helper to read bits out of global. C is the constant being copied
 /// out of. ByteOffset is an offset into C. CurPtr is the pointer to copy
 /// results into and BytesLeft is the number of bytes left in