[LoongArch] Replace assertion by error message while lowering RETURNADDR and FRAMEADDR

[gonglingqin]

Summary

If __builtin_frame_address or __builtin_return_address is invoked with
non-zero argument, show an error message instead of a crash.

Reference: https://reviews.llvm.org/rG83b88441ad951fe99c30402930ef3cd661f2fd2b

[xen0n]

llvm/test/CodeGen/LoongArch/frameaddr-returnaddr-error.ll

20

nit: "for the current frame"?

[gonglingqin]

llvm/test/CodeGen/LoongArch/frameaddr-returnaddr-error.ll

20

Thanks, I will modify it.

[gonglingqin]

Address @xen0n's comments.

llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp

SDValue LoongArchTargetLowering::lowerFRAMEADDR(SDValue Op,
                                                 SelectionDAG &DAG) const {
   if (!isa<ConstantSDNode>(Op.getOperand(0))) {
     DAG.getContext()->emitError("argument to '__builtin_frame_address' must "
                                 "be a constant integer");
     return SDValue();
   }
 
   // Currently only support lowering frame address for current frame.
-  unsigned Depth = cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue();
-  assert((Depth == 0) &&
-         "Frame address can only be determined for current frame.");
-  if (Depth != 0)
+  if (cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue() != 0) {
+    DAG.getContext()->emitError(
+        "frame address can only be determined for current frame");
     return SDValue();
+  }
 
   MachineFunction &MF = DAG.getMachineFunction();
   MF.getFrameInfo().setFrameAddressIsTaken(true);
 
   return DAG.getCopyFromReg(DAG.getEntryNode(), SDLoc(Op),
                             Subtarget.getRegisterInfo()->getFrameRegister(MF),
                             Op.getValueType());
 }
 
 SDValue LoongArchTargetLowering::lowerRETURNADDR(SDValue Op,
                                                  SelectionDAG &DAG) const {
   if (verifyReturnAddressArgumentIsConstant(Op, DAG))
     return SDValue();
 
   // Currently only support lowering return address for current frame.
-  unsigned Depth = cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue();
-  assert((Depth == 0) &&
-         "Return address can only be determined for current frame.");
-  if (Depth != 0)
+  if (cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue() != 0) {
+    DAG.getContext()->emitError(
+        "return address can only be determined for current frame");
     return SDValue();
+  }
 
   MachineFunction &MF = DAG.getMachineFunction();
   MF.getFrameInfo().setReturnAddressIsTaken(true);
   MVT GRLenVT = Subtarget.getGRLenVT();
 
   // Return the value of the return address register, marking it an implicit
   // live-in.
   Register Reg = MF.addLiveIn(Subtarget.getRegisterInfo()->getRARegister(),

llvm/test/CodeGen/LoongArch/frameaddr-returnaddr-error.ll

 
 
 define ptr @non_const_depth_returnaddress(i32 %x) nounwind {
 ; CHECK: argument to '__builtin_return_address' must be a constant integer
   %1 = call ptr @llvm.returnaddress(i32 %x)
   ret ptr %1
 }
 
+define ptr @non_zero_frameaddress() nounwind {
+; CHECK: frame address can only be determined for current frame
+  %1 = call ptr @llvm.frameaddress(i32 1)
+  ret ptr %1
+}
+
+
+define ptr @non_zero_returnaddress() nounwind {
+; CHECK: return address can only be determined for current frame
+  %1 = call ptr @llvm.returnaddress(i32 1)
+  ret ptr %1
+}
+