Index: llvm/trunk/include/llvm/CodeGen/GlobalISel/CallLowering.h
===================================================================
--- llvm/trunk/include/llvm/CodeGen/GlobalISel/CallLowering.h
+++ llvm/trunk/include/llvm/CodeGen/GlobalISel/CallLowering.h
@@ -240,11 +240,12 @@
   /// \return true if the lowering succeeded, false otherwise.
   virtual bool lowerCall(MachineIRBuilder &MIRBuilder, CallingConv::ID CallConv,
                          const MachineOperand &Callee, const ArgInfo &OrigRet,
-                         ArrayRef<ArgInfo> OrigArgs,
-                         Register SwiftErrorVReg) const {
+                         ArrayRef<ArgInfo> OrigArgs, Register SwiftErrorVReg,
+                         const MDNode *KnownCallees = nullptr) const {
     if (!supportSwiftError()) {
       assert(SwiftErrorVReg == 0 && "trying to use unsupported swifterror");
-      return lowerCall(MIRBuilder, CallConv, Callee, OrigRet, OrigArgs);
+      return lowerCall(MIRBuilder, CallConv, Callee, OrigRet, OrigArgs,
+                       KnownCallees);
     }
     return false;
   }
@@ -253,7 +254,8 @@
   /// do not support swifterror value promotion.
   virtual bool lowerCall(MachineIRBuilder &MIRBuilder, CallingConv::ID CallConv,
                          const MachineOperand &Callee, const ArgInfo &OrigRet,
-                         ArrayRef<ArgInfo> OrigArgs) const {
+                         ArrayRef<ArgInfo> OrigArgs,
+                         const MDNode *KnownCallees = nullptr) const {
     return false;
   }
 
Index: llvm/trunk/lib/CodeGen/GlobalISel/CallLowering.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/GlobalISel/CallLowering.cpp
+++ llvm/trunk/lib/CodeGen/GlobalISel/CallLowering.cpp
@@ -19,6 +19,7 @@
 #include "llvm/CodeGen/TargetLowering.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/Instructions.h"
+#include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
 
 #define DEBUG_TYPE "call-lowering"
@@ -61,8 +62,11 @@
   if (!OrigRet.Ty->isVoidTy())
     setArgFlags(OrigRet, AttributeList::ReturnIndex, DL, CS);
 
+  const MDNode *KnownCallees =
+      CS.getInstruction()->getMetadata(LLVMContext::MD_callees);
+
   return lowerCall(MIRBuilder, CS.getCallingConv(), Callee, OrigRet, OrigArgs,
-                   SwiftErrorVReg);
+                   SwiftErrorVReg, KnownCallees);
 }
 
 template <typename FuncInfoTy>
Index: llvm/trunk/lib/Target/AArch64/AArch64CallLowering.h
===================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64CallLowering.h
+++ llvm/trunk/lib/Target/AArch64/AArch64CallLowering.h
@@ -42,13 +42,15 @@
 
   bool lowerCall(MachineIRBuilder &MIRBuilder, CallingConv::ID CallConv,
                  const MachineOperand &Callee, const ArgInfo &OrigRet,
-                 ArrayRef<ArgInfo> OrigArgs,
-                 Register SwiftErrorVReg) const override;
+                 ArrayRef<ArgInfo> OrigArgs, Register SwiftErrorVReg,
+                 const MDNode *KnownCallees) const override;
 
   bool lowerCall(MachineIRBuilder &MIRBuilder, CallingConv::ID CallConv,
                  const MachineOperand &Callee, const ArgInfo &OrigRet,
-                 ArrayRef<ArgInfo> OrigArgs) const override {
-    return lowerCall(MIRBuilder, CallConv, Callee, OrigRet, OrigArgs, 0);
+                 ArrayRef<ArgInfo> OrigArgs,
+                 const MDNode *KnownCallees) const override {
+    return lowerCall(MIRBuilder, CallConv, Callee, OrigRet, OrigArgs, 0,
+                     KnownCallees);
   }
 
   bool supportSwiftError() const override { return true; }
Index: llvm/trunk/lib/Target/AArch64/AArch64CallLowering.cpp
===================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64CallLowering.cpp
+++ llvm/trunk/lib/Target/AArch64/AArch64CallLowering.cpp
@@ -406,7 +406,8 @@
                                     const MachineOperand &Callee,
                                     const ArgInfo &OrigRet,
                                     ArrayRef<ArgInfo> OrigArgs,
-                                    Register SwiftErrorVReg) const {
+                                    Register SwiftErrorVReg,
+                                    const MDNode *KnownCallees) const {
   MachineFunction &MF = MIRBuilder.getMF();
   const Function &F = MF.getFunction();
   MachineRegisterInfo &MRI = MF.getRegInfo();
Index: llvm/trunk/lib/Target/ARM/ARMCallLowering.h
===================================================================
--- llvm/trunk/lib/Target/ARM/ARMCallLowering.h
+++ llvm/trunk/lib/Target/ARM/ARMCallLowering.h
@@ -40,7 +40,8 @@
 
   bool lowerCall(MachineIRBuilder &MIRBuilder, CallingConv::ID CallConv,
                  const MachineOperand &Callee, const ArgInfo &OrigRet,
-                 ArrayRef<ArgInfo> OrigArgs) const override;
+                 ArrayRef<ArgInfo> OrigArgs,
+                 const MDNode *KnownCallees) const override;
 
 private:
   bool lowerReturnVal(MachineIRBuilder &MIRBuilder, const Value *Val,
Index: llvm/trunk/lib/Target/ARM/ARMCallLowering.cpp
===================================================================
--- llvm/trunk/lib/Target/ARM/ARMCallLowering.cpp
+++ llvm/trunk/lib/Target/ARM/ARMCallLowering.cpp
@@ -502,7 +502,8 @@
                                 CallingConv::ID CallConv,
                                 const MachineOperand &Callee,
                                 const ArgInfo &OrigRet,
-                                ArrayRef<ArgInfo> OrigArgs) const {
+                                ArrayRef<ArgInfo> OrigArgs,
+                                const MDNode *KnownCallees) const {
   MachineFunction &MF = MIRBuilder.getMF();
   const auto &TLI = *getTLI<ARMTargetLowering>();
   const auto &DL = MF.getDataLayout();
Index: llvm/trunk/lib/Target/Mips/MipsCallLowering.h
===================================================================
--- llvm/trunk/lib/Target/Mips/MipsCallLowering.h
+++ llvm/trunk/lib/Target/Mips/MipsCallLowering.h
@@ -70,7 +70,8 @@
 
   bool lowerCall(MachineIRBuilder &MIRBuilder, CallingConv::ID CallConv,
                  const MachineOperand &Callee, const ArgInfo &OrigRet,
-                 ArrayRef<ArgInfo> OrigArgs) const override;
+                 ArrayRef<ArgInfo> OrigArgs,
+                 const MDNode *KnownCallees) const override;
 
 private:
   /// Based on registers available on target machine split or extend
Index: llvm/trunk/lib/Target/Mips/MipsCallLowering.cpp
===================================================================
--- llvm/trunk/lib/Target/Mips/MipsCallLowering.cpp
+++ llvm/trunk/lib/Target/Mips/MipsCallLowering.cpp
@@ -502,7 +502,8 @@
                                  CallingConv::ID CallConv,
                                  const MachineOperand &Callee,
                                  const ArgInfo &OrigRet,
-                                 ArrayRef<ArgInfo> OrigArgs) const {
+                                 ArrayRef<ArgInfo> OrigArgs,
+                                 const MDNode *KnownCallees) const {
 
   if (CallConv != CallingConv::C)
     return false;
Index: llvm/trunk/lib/Target/X86/X86CallLowering.h
===================================================================
--- llvm/trunk/lib/Target/X86/X86CallLowering.h
+++ llvm/trunk/lib/Target/X86/X86CallLowering.h
@@ -36,7 +36,8 @@
 
   bool lowerCall(MachineIRBuilder &MIRBuilder, CallingConv::ID CallConv,
                  const MachineOperand &Callee, const ArgInfo &OrigRet,
-                 ArrayRef<ArgInfo> OrigArgs) const override;
+                 ArrayRef<ArgInfo> OrigArgs,
+                 const MDNode *KnownCallees) const override;
 
 private:
   /// A function of this type is used to perform value split action.
Index: llvm/trunk/lib/Target/X86/X86CallLowering.cpp
===================================================================
--- llvm/trunk/lib/Target/X86/X86CallLowering.cpp
+++ llvm/trunk/lib/Target/X86/X86CallLowering.cpp
@@ -375,7 +375,8 @@
                                 CallingConv::ID CallConv,
                                 const MachineOperand &Callee,
                                 const ArgInfo &OrigRet,
-                                ArrayRef<ArgInfo> OrigArgs) const {
+                                ArrayRef<ArgInfo> OrigArgs,
+                                const MDNode *KnownCallees) const {
   MachineFunction &MF = MIRBuilder.getMF();
   const Function &F = MF.getFunction();
   MachineRegisterInfo &MRI = MF.getRegInfo();