Some ARM implementaions, e.g. A-series, does return stack prediction. That is,

the processor keeps a return addresses stack (RAS) which stores the address
and the instruction execution state of the instruction after a function-call
type branch instruction.

Calling a "noreturn" function with normal call instructions (e.g. bl) can
corrupt RAS and causes 100% return misprediction so LLVM should use a
unconditional branch instead. i.e.
mov lr, pc
b _foo
The "mov lr, pc" is issued in order to get proper backtrace.

rdar://8979299


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151623 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 29 insertions, 20 deletions

diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 302c83d..31df458 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -1788,7 +1788,7 @@ SDValue SelectionDAGLegalize::ExpandLibCall(RTLIB::Libcall LC, SDNode *Node,
   std::pair<SDValue, SDValue> CallInfo =
     TLI.LowerCallTo(InChain, RetTy, isSigned, !isSigned, false, false,
                     0, TLI.getLibcallCallingConv(LC), isTailCall,
-                    /*isReturnValueUsed=*/true,
+                    /*doesNotReturn=*/false, /*isReturnValueUsed=*/true,
                     Callee, Args, DAG, Node->getDebugLoc());
 
   if (!CallInfo.second.getNode())
@@ -1821,7 +1821,7 @@ SDValue SelectionDAGLegalize::ExpandLibCall(RTLIB::Libcall LC, EVT RetVT,
   std::pair<SDValue,SDValue> CallInfo =
   TLI.LowerCallTo(DAG.getEntryNode(), RetTy, isSigned, !isSigned, false,
                   false, 0, TLI.getLibcallCallingConv(LC), false,
-                  /*isReturnValueUsed=*/true,
+                  /*doesNotReturn=*/false, /*isReturnValueUsed=*/true,
                   Callee, Args, DAG, dl);
 
   return CallInfo.first;
@@ -1853,7 +1853,7 @@ SelectionDAGLegalize::ExpandChainLibCall(RTLIB::Libcall LC,
   std::pair<SDValue, SDValue> CallInfo =
     TLI.LowerCallTo(InChain, RetTy, isSigned, !isSigned, false, false,
                     0, TLI.getLibcallCallingConv(LC), /*isTailCall=*/false,
-                    /*isReturnValueUsed=*/true,
+                    /*doesNotReturn=*/false, /*isReturnValueUsed=*/true,
                     Callee, Args, DAG, Node->getDebugLoc());
 
   return CallInfo;
@@ -1985,7 +1985,8 @@ SelectionDAGLegalize::ExpandDivRemLibCall(SDNode *Node,
   std::pair<SDValue, SDValue> CallInfo =
     TLI.LowerCallTo(InChain, RetTy, isSigned, !isSigned, false, false,
                     0, TLI.getLibcallCallingConv(LC), /*isTailCall=*/false,
-                    /*isReturnValueUsed=*/true, Callee, Args, DAG, dl);
+                    /*doesNotReturn=*/false, /*isReturnValueUsed=*/true,
+                    Callee, Args, DAG, dl);
 
   // Remainder is loaded back from the stack frame.
   SDValue Rem = DAG.getLoad(RetVT, dl, CallInfo.second, FIPtr,
@@ -2563,7 +2564,7 @@ void SelectionDAGLegalize::ExpandNode(SDNode *Node) {
       TLI.LowerCallTo(Node->getOperand(0), Type::getVoidTy(*DAG.getContext()),
                       false, false, false, false, 0, CallingConv::C,
                       /*isTailCall=*/false,
-                      /*isReturnValueUsed=*/true,
+                      /*doesNotReturn=*/false, /*isReturnValueUsed=*/true,
                       DAG.getExternalSymbol("__sync_synchronize",
                                             TLI.getPointerTy()),
                       Args, DAG, dl);
@@ -2640,7 +2641,7 @@ void SelectionDAGLegalize::ExpandNode(SDNode *Node) {
       TLI.LowerCallTo(Node->getOperand(0), Type::getVoidTy(*DAG.getContext()),
                       false, false, false, false, 0, CallingConv::C,
                       /*isTailCall=*/false,
-                      /*isReturnValueUsed=*/true,
+                      /*doesNotReturn=*/false, /*isReturnValueUsed=*/true,
                       DAG.getExternalSymbol("abort", TLI.getPointerTy()),
                       Args, DAG, dl);
     Results.push_back(CallResult.second);
diff --git a/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp b/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
index d18766a..caf6df9 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
@@ -2311,8 +2311,10 @@ void DAGTypeLegalizer::ExpandIntRes_XMULO(SDNode *N,
   SDValue Func = DAG.getExternalSymbol(TLI.getLibcallName(LC), PtrVT);
   std::pair<SDValue, SDValue> CallInfo =
     TLI.LowerCallTo(Chain, RetTy, true, false, false, false,
-		    0, TLI.getLibcallCallingConv(LC), false,
-		    true, Func, Args, DAG, dl);
+		    0, TLI.getLibcallCallingConv(LC),
+                    /*isTailCall=*/false,
+		    /*doesNotReturn=*/false, /*isReturnValueUsed=*/true,
+                    Func, Args, DAG, dl);
 
   SplitInteger(CallInfo.first, Lo, Hi);
   SDValue Temp2 = DAG.getLoad(PtrVT, dl, CallInfo.second, Temp,
diff --git a/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp b/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
index 897953f..439aa4d 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
@@ -1056,8 +1056,9 @@ SDValue DAGTypeLegalizer::MakeLibCall(RTLIB::Libcall LC, EVT RetVT,
   Type *RetTy = RetVT.getTypeForEVT(*DAG.getContext());
   std::pair<SDValue,SDValue> CallInfo =
     TLI.LowerCallTo(DAG.getEntryNode(), RetTy, isSigned, !isSigned, false,
-                    false, 0, TLI.getLibcallCallingConv(LC), false,
-                    /*isReturnValueUsed=*/true,
+                    false, 0, TLI.getLibcallCallingConv(LC),
+                    /*isTailCall=*/false,
+                    /*doesNotReturn=*/false, /*isReturnValueUsed=*/true,
                     Callee, Args, DAG, dl);
   return CallInfo.first;
 }
@@ -1088,7 +1089,7 @@ DAGTypeLegalizer::ExpandChainLibCall(RTLIB::Libcall LC,
   std::pair<SDValue, SDValue> CallInfo =
     TLI.LowerCallTo(InChain, RetTy, isSigned, !isSigned, false, false,
                     0, TLI.getLibcallCallingConv(LC), /*isTailCall=*/false,
-                    /*isReturnValueUsed=*/true,
+                    /*doesNotReturn=*/false, /*isReturnValueUsed=*/true,
                     Callee, Args, DAG, Node->getDebugLoc());
 
   return CallInfo;
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index fc8c531..796abf4 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -3736,8 +3736,9 @@ SDValue SelectionDAG::getMemcpy(SDValue Chain, DebugLoc dl, SDValue Dst,
   std::pair<SDValue,SDValue> CallResult =
     TLI.LowerCallTo(Chain, Type::getVoidTy(*getContext()),
                     false, false, false, false, 0,
-                    TLI.getLibcallCallingConv(RTLIB::MEMCPY), false,
-                    /*isReturnValueUsed=*/false,
+                    TLI.getLibcallCallingConv(RTLIB::MEMCPY),
+                    /*isTailCall=*/false,
+                    /*doesNotReturn=*/false, /*isReturnValueUsed=*/false,
                     getExternalSymbol(TLI.getLibcallName(RTLIB::MEMCPY),
                                       TLI.getPointerTy()),
                     Args, *this, dl);
@@ -3788,8 +3789,9 @@ SDValue SelectionDAG::getMemmove(SDValue Chain, DebugLoc dl, SDValue Dst,
   std::pair<SDValue,SDValue> CallResult =
     TLI.LowerCallTo(Chain, Type::getVoidTy(*getContext()),
                     false, false, false, false, 0,
-                    TLI.getLibcallCallingConv(RTLIB::MEMMOVE), false,
-                    /*isReturnValueUsed=*/false,
+                    TLI.getLibcallCallingConv(RTLIB::MEMMOVE),
+                    /*isTailCall=*/false,
+                    /*doesNotReturn=*/false, /*isReturnValueUsed=*/false,
                     getExternalSymbol(TLI.getLibcallName(RTLIB::MEMMOVE),
                                       TLI.getPointerTy()),
                     Args, *this, dl);
@@ -3848,8 +3850,9 @@ SDValue SelectionDAG::getMemset(SDValue Chain, DebugLoc dl, SDValue Dst,
   std::pair<SDValue,SDValue> CallResult =
     TLI.LowerCallTo(Chain, Type::getVoidTy(*getContext()),
                     false, false, false, false, 0,
-                    TLI.getLibcallCallingConv(RTLIB::MEMSET), false,
-                    /*isReturnValueUsed=*/false,
+                    TLI.getLibcallCallingConv(RTLIB::MEMSET),
+                    /*isTailCall=*/false,
+                    /*doesNotReturn*/false, /*isReturnValueUsed=*/false,
                     getExternalSymbol(TLI.getLibcallName(RTLIB::MEMSET),
                                       TLI.getPointerTy()),
                     Args, *this, dl);
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 44de41f..ca64c90 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -5081,7 +5081,8 @@ SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
     std::pair<SDValue, SDValue> Result =
       TLI.LowerCallTo(getRoot(), I.getType(),
                  false, false, false, false, 0, CallingConv::C,
-                 /*isTailCall=*/false, /*isReturnValueUsed=*/true,
+                 /*isTailCall=*/false,
+                 /*doesNotRet=*/false, /*isReturnValueUsed=*/true,
                  DAG.getExternalSymbol(TrapFuncName.data(), TLI.getPointerTy()),
                  Args, DAG, getCurDebugLoc());
     DAG.setRoot(Result.second);
@@ -5244,6 +5245,7 @@ void SelectionDAGBuilder::LowerCallTo(ImmutableCallSite CS, SDValue Callee,
                     CS.paramHasAttr(0, Attribute::InReg), FTy->getNumParams(),
                     CS.getCallingConv(),
                     isTailCall,
+                    CS.doesNotReturn(),
                     !CS.getInstruction()->use_empty(),
                     Callee, Args, DAG, getCurDebugLoc());
   assert((isTailCall || Result.second.getNode()) &&
@@ -6360,7 +6362,7 @@ TargetLowering::LowerCallTo(SDValue Chain, Type *RetTy,
                             bool RetSExt, bool RetZExt, bool isVarArg,
                             bool isInreg, unsigned NumFixedArgs,
                             CallingConv::ID CallConv, bool isTailCall,
-                            bool isReturnValueUsed,
+                            bool doesNotRet, bool isReturnValueUsed,
                             SDValue Callee,
                             ArgListTy &Args, SelectionDAG &DAG,
                             DebugLoc dl) const {
@@ -6457,7 +6459,7 @@ TargetLowering::LowerCallTo(SDValue Chain, Type *RetTy,
   }
 
   SmallVector<SDValue, 4> InVals;
-  Chain = LowerCall(Chain, Callee, CallConv, isVarArg, isTailCall,
+  Chain = LowerCall(Chain, Callee, CallConv, isVarArg, doesNotRet, isTailCall,
                     Outs, OutVals, Ins, dl, DAG, InVals);
 
   // Verify that the target's LowerCall behaved as expected.