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
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 @@
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 @@
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 @@
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 @@
}
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.