3 files changed, 47 insertions, 2 deletions
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 4b1945efe4..81058152eb 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -967,6 +967,13 @@ SDValue DAGCombiner::visitADD(SDNode *N) {
   // fold (add x, 0) -> x
   if (N1C && N1C->isNullValue())
     return N0;
+  // fold (add Sym, c) -> Sym+c
+  if (GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(N0))
+    if (!AfterLegalize && TLI.isOffsetFoldingLegal(GA) && N1C &&
+        GA->getOpcode() == ISD::GlobalAddress)
+      return DAG.getGlobalAddress(GA->getGlobal(), VT,
+                                  GA->getOffset() +
+                                    (uint64_t)N1C->getSExtValue());
   // fold ((c1-A)+c2) -> (c1+c2)-A
   if (N1C && N0.getOpcode() == ISD::SUB)
     if (ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0.getOperand(0)))
@@ -1133,6 +1140,21 @@ SDValue DAGCombiner::visitSUB(SDNode *N) {
   if (N1.getOpcode() == ISD::UNDEF)
     return N1;
 
+  // If the relocation model supports it, consider symbol offsets.
+  if (GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(N0))
+    if (!AfterLegalize && TLI.isOffsetFoldingLegal(GA)) {
+      // fold (sub Sym, c) -> Sym-c
+      if (N1C && GA->getOpcode() == ISD::GlobalAddress)
+        return DAG.getGlobalAddress(GA->getGlobal(), VT,
+                                    GA->getOffset() -
+                                      (uint64_t)N1C->getSExtValue());
+      // fold (sub Sym+c1, Sym+c2) -> c1-c2
+      if (GlobalAddressSDNode *GB = dyn_cast<GlobalAddressSDNode>(N1))
+        if (GA->getGlobal() == GB->getGlobal())
+          return DAG.getConstant((uint64_t)GA->getOffset() - GB->getOffset(),
+                                 VT);
+    }
+
   return SDValue();
 }
 
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 9cfb1a1a22..07819404e1 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -959,10 +959,15 @@ SDValue SelectionDAG::getConstantFP(double Val, MVT VT, bool isTarget) {
 }
 
 SDValue SelectionDAG::getGlobalAddress(const GlobalValue *GV,
-                                       MVT VT, int Offset,
+                                       MVT VT, int64_t Offset,
                                        bool isTargetGA) {
   unsigned Opc;
 
+  // Truncate (with sign-extension) the offset value to the pointer size.
+  unsigned BitWidth = VT.getSizeInBits();
+  if (BitWidth < 64)
+    Offset = (Offset << (64 - BitWidth) >> (64 - BitWidth));
+
   const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
   if (!GVar) {
     // If GV is an alias then use the aliasee for determining thread-localness.
@@ -2017,6 +2022,7 @@ unsigned SelectionDAG::ComputeNumSignBits(SDValue Op, unsigned Depth) const{
 bool SelectionDAG::isVerifiedDebugInfoDesc(SDValue Op) const {
   GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(Op);
   if (!GA) return false;
+  if (GA->getOffset() != 0) return false;
   GlobalVariable *GV = dyn_cast<GlobalVariable>(GA->getGlobal());
   if (!GV) return false;
   MachineModuleInfo *MMI = getMachineModuleInfo();
@@ -4726,7 +4732,7 @@ HandleSDNode::~HandleSDNode() {
 }
 
 GlobalAddressSDNode::GlobalAddressSDNode(bool isTarget, const GlobalValue *GA,
-                                         MVT VT, int o)
+                                         MVT VT, int64_t o)
   : SDNode(isa<GlobalVariable>(GA) &&
            cast<GlobalVariable>(GA)->isThreadLocal() ?
            // Thread Local
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 479e1380c5..1e7e847b8a 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -656,6 +656,23 @@ SDValue TargetLowering::getPICJumpTableRelocBase(SDValue Table,
   return Table;
 }
 
+bool
+TargetLowering::isOffsetFoldingLegal(const GlobalAddressSDNode *GA) const {
+  // Assume that everything is safe in static mode.
+  if (getTargetMachine().getRelocationModel() == Reloc::Static)
+    return true;
+
+  // In dynamic-no-pic mode, assume that known defined values are safe.
+  if (getTargetMachine().getRelocationModel() == Reloc::DynamicNoPIC &&
+      GA &&
+      !GA->getGlobal()->isDeclaration() &&
+      !GA->getGlobal()->mayBeOverridden())
+    return true;
+
+  // Otherwise assume nothing is safe.
+  return false;
+}
+
 //===----------------------------------------------------------------------===//
 //  Optimization Methods
 //===----------------------------------------------------------------------===//