2 files changed, 10 insertions, 21 deletions
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 284b984f0a..495418d999 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -4197,8 +4197,9 @@ SelectionDAGBuilder::visitIntrinsicCall(CallInst &I, unsigned Intrinsic) {
 ///
 /// This function only tests target-independent requirements.
 static bool
-isInTailCallPosition(const Instruction *I, Attributes CalleeRetAttr,
+isInTailCallPosition(CallSite CS, Attributes CalleeRetAttr,
                      const TargetLowering &TLI) {
+  const Instruction *I = CS.getInstruction();
   const BasicBlock *ExitBB = I->getParent();
   const TerminatorInst *Term = ExitBB->getTerminator();
   const ReturnInst *Ret = dyn_cast<ReturnInst>(Term);
@@ -4207,6 +4208,12 @@ isInTailCallPosition(const Instruction *I, Attributes CalleeRetAttr,
   // The block must end in a return statement or an unreachable.
   if (!Ret && !isa<UnreachableInst>(Term)) return false;
 
+  // Unless we are explicitly forcing tailcall optimization do not tailcall if
+  // the called function is bitcast'ed. The analysis may not be entirely
+  // accurate.
+  if (!PerformTailCallOpt && isa<BitCastInst>(CS.getCalledValue()))
+    return false;
+
   // If I will have a chain, make sure no other instruction that will have a
   // chain interposes between I and the return.
   if (I->mayHaveSideEffects() || I->mayReadFromMemory() ||
@@ -4348,9 +4355,7 @@ void SelectionDAGBuilder::LowerCallTo(CallSite CS, SDValue Callee,
   // Check if target-independent constraints permit a tail call here.
   // Target-dependent constraints are checked within TLI.LowerCallTo.
   if (isTailCall &&
-      !isInTailCallPosition(CS.getInstruction(),
-                            CS.getAttributes().getRetAttributes(),
-                            TLI))
+      !isInTailCallPosition(CS, CS.getAttributes().getRetAttributes(), TLI))
     isTailCall = false;
 
   std::pair<SDValue,SDValue> Result =
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 6f710ecbe1..9d6b5a39b2 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -2269,7 +2269,6 @@ X86TargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,
     return false;
   }
 
-
   // Look for obvious safe cases to perform tail call optimization that does not
   // requite ABI changes. This is what gcc calls sibcall.
 
@@ -2324,22 +2323,7 @@ X86TargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,
     }
   }
 
-  // If the caller does not return a value, then this is obviously safe.
-  // This is one case where it's safe to perform this optimization even
-  // if the return types do not match.
-  const Type *CallerRetTy = CallerF->getReturnType();
-  if (CallerRetTy->isVoidTy())
-    return true;
-
-  // If the return types match, then it's safe.
-  // Don't tail call optimize recursive call.
-  GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee);
-  if (!G) return false;  // FIXME: common external symbols?
-  if (const Function *CalleeF = dyn_cast<Function>(G->getGlobal())) {
-    const Type *CalleeRetTy = CalleeF->getReturnType();
-    return CallerRetTy == CalleeRetTy;
-  }
-  return false;
+  return true;
 }
 
 FastISel *