Automerge: CodeGen: Emit error if getRegisterByName fails (#145194)

This avoids using report_fatal_error and standardizes the error
message in a subset of the error conditions.

Author: arsenm

llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp

@@ -9107,8 +9107,18 @@ LegalizerHelper::lowerReadWriteRegister(MachineInstr &MI) {
     cast<MDNode>(MI.getOperand(NameOpIdx).getMetadata())->getOperand(0));
 
   Register PhysReg = TLI.getRegisterByName(RegStr->getString().data(), Ty, MF);
-  if (!PhysReg.isValid())
-    return UnableToLegalize;
+  if (!PhysReg) {
+    const Function &Fn = MF.getFunction();
+    Fn.getContext().diagnose(DiagnosticInfoGenericWithLoc(
+        "invalid register \"" + Twine(RegStr->getString().data()) + "\" for " +
+            (IsRead ? "llvm.read_register" : "llvm.write_register"),
+        Fn, MI.getDebugLoc()));
+    if (IsRead)
+      MIRBuilder.buildUndef(ValReg);
+
+    MI.eraseFromParent();
+    return Legalized;
+  }
 
   if (IsRead)
     MIRBuilder.buildCopy(ValReg, PhysReg);

llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

@@ -2460,11 +2460,25 @@ void SelectionDAGISel::Select_READ_REGISTER(SDNode *Op) {
 
   EVT VT = Op->getValueType(0);
   LLT Ty = VT.isSimple() ? getLLTForMVT(VT.getSimpleVT()) : LLT();
-  Register Reg =
-      TLI->getRegisterByName(RegStr->getString().data(), Ty,
-                             CurDAG->getMachineFunction());
-  SDValue New = CurDAG->getCopyFromReg(
-                        Op->getOperand(0), dl, Reg, Op->getValueType(0));
+
+  const MachineFunction &MF = CurDAG->getMachineFunction();
+  Register Reg = TLI->getRegisterByName(RegStr->getString().data(), Ty, MF);
+
+  SDValue New;
+  if (!Reg) {
+    const Function &Fn = MF.getFunction();
+    Fn.getContext().diagnose(DiagnosticInfoGenericWithLoc(
+        "invalid register \"" + Twine(RegStr->getString().data()) +
+            "\" for llvm.read_register",
+        Fn, Op->getDebugLoc()));
+    New =
+        SDValue(CurDAG->getMachineNode(TargetOpcode::IMPLICIT_DEF, dl, VT), 0);
+    ReplaceUses(SDValue(Op, 1), Op->getOperand(0));
+  } else {
+    New =
+        CurDAG->getCopyFromReg(Op->getOperand(0), dl, Reg, Op->getValueType(0));
+  }
+
   New->setNodeId(-1);
   ReplaceUses(Op, New.getNode());
   CurDAG->RemoveDeadNode(Op);
@@ -2478,12 +2492,23 @@ void SelectionDAGISel::Select_WRITE_REGISTER(SDNode *Op) {
   EVT VT = Op->getOperand(2).getValueType();
   LLT Ty = VT.isSimple() ? getLLTForMVT(VT.getSimpleVT()) : LLT();
 
-  Register Reg = TLI->getRegisterByName(RegStr->getString().data(), Ty,
-                                        CurDAG->getMachineFunction());
-  SDValue New = CurDAG->getCopyToReg(
-                        Op->getOperand(0), dl, Reg, Op->getOperand(2));
-  New->setNodeId(-1);
-  ReplaceUses(Op, New.getNode());
+  const MachineFunction &MF = CurDAG->getMachineFunction();
+  Register Reg = TLI->getRegisterByName(RegStr->getString().data(), Ty, MF);
+
+  if (!Reg) {
+    const Function &Fn = MF.getFunction();
+    Fn.getContext().diagnose(DiagnosticInfoGenericWithLoc(
+        "invalid register \"" + Twine(RegStr->getString().data()) +
+            "\" for llvm.write_register",
+        Fn, Op->getDebugLoc()));
+    ReplaceUses(SDValue(Op, 0), Op->getOperand(0));
+  } else {
+    SDValue New =
+        CurDAG->getCopyToReg(Op->getOperand(0), dl, Reg, Op->getOperand(2));
+    New->setNodeId(-1);
+    ReplaceUses(Op, New.getNode());
+  }
+
   CurDAG->RemoveDeadNode(Op);
 }
 

llvm/lib/Target/AArch64/AArch64ISelLowering.cpp

@@ -11977,12 +11977,9 @@ getRegisterByName(const char* RegName, LLT VT, const MachineFunction &MF) const
     unsigned DwarfRegNum = MRI->getDwarfRegNum(Reg, false);
     if (!Subtarget->isXRegisterReserved(DwarfRegNum) &&
         !MRI->isReservedReg(MF, Reg))
-      Reg = 0;
+      Reg = Register();
   }
-  if (Reg)
-    return Reg;
-  report_fatal_error(Twine("Invalid register name \""
-                              + StringRef(RegName)  + "\"."));
+  return Reg;
 }
 
 SDValue AArch64TargetLowering::LowerADDROFRETURNADDR(SDValue Op,

llvm/lib/Target/AMDGPU/SIISelLowering.cpp

@@ -4492,11 +4492,8 @@ Register SITargetLowering::getRegisterByName(const char *RegName, LLT VT,
                      .Case("flat_scratch_lo", AMDGPU::FLAT_SCR_LO)
                      .Case("flat_scratch_hi", AMDGPU::FLAT_SCR_HI)
                      .Default(Register());
-
-  if (Reg == AMDGPU::NoRegister) {
-    report_fatal_error(
-        Twine("invalid register name \"" + StringRef(RegName) + "\"."));
-  }
+  if (!Reg)
+    return Reg;
 
   if (!Subtarget->hasFlatScrRegister() &&
       Subtarget->getRegisterInfo()->regsOverlap(Reg, AMDGPU::FLAT_SCR)) {

llvm/lib/Target/ARM/ARMISelLowering.cpp

@@ -6166,13 +6166,9 @@ SDValue ARMTargetLowering::LowerFRAMEADDR(SDValue Op, SelectionDAG &DAG) const {
 // this table could be generated automatically from RegInfo.
 Register ARMTargetLowering::getRegisterByName(const char* RegName, LLT VT,
                                               const MachineFunction &MF) const {
-  Register Reg = StringSwitch<unsigned>(RegName)
-                       .Case("sp", ARM::SP)
-                       .Default(0);
-  if (Reg)
-    return Reg;
-  report_fatal_error(Twine("Invalid register name \""
-                              + StringRef(RegName)  + "\"."));
+  return StringSwitch<Register>(RegName)
+      .Case("sp", ARM::SP)
+      .Default(Register());
 }
 
 // Result is 64 bit value so split into two 32 bit values and return as a

llvm/lib/Target/Hexagon/HexagonISelLowering.cpp

@@ -329,10 +329,7 @@ Register HexagonTargetLowering::getRegisterByName(
                      .Case("cs0", Hexagon::CS0)
                      .Case("cs1", Hexagon::CS1)
                      .Default(Register());
-  if (Reg)
-    return Reg;
-
-  report_fatal_error("Invalid register name global variable");
+  return Reg;
 }
 
 /// LowerCallResult - Lower the result values of an ISD::CALL into the

llvm/lib/Target/Lanai/LanaiISelLowering.cpp

@@ -211,7 +211,7 @@ Register LanaiTargetLowering::getRegisterByName(
   const char *RegName, LLT /*VT*/,
   const MachineFunction & /*MF*/) const {
   // Only unallocatable registers should be matched here.
-  Register Reg = StringSwitch<unsigned>(RegName)
+  Register Reg = StringSwitch<Register>(RegName)
                      .Case("pc", Lanai::PC)
                      .Case("sp", Lanai::SP)
                      .Case("fp", Lanai::FP)
@@ -220,11 +220,8 @@ Register LanaiTargetLowering::getRegisterByName(
                      .Case("rr2", Lanai::RR2)
                      .Case("r11", Lanai::R11)
                      .Case("rca", Lanai::RCA)
-                     .Default(0);
-
-  if (Reg)
-    return Reg;
-  report_fatal_error("Invalid register name global variable");
+                     .Default(Register());
+  return Reg;
 }
 
 std::pair<unsigned, const TargetRegisterClass *>

llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp

@@ -7957,11 +7957,10 @@ LoongArchTargetLowering::getRegisterByName(const char *RegName, LLT VT,
   std::pair<StringRef, StringRef> Name = StringRef(RegName).split('$');
   std::string NewRegName = Name.second.str();
   Register Reg = MatchRegisterAltName(NewRegName);
-  if (Reg == LoongArch::NoRegister)
+  if (!Reg)
     Reg = MatchRegisterName(NewRegName);
-  if (Reg == LoongArch::NoRegister)
-    report_fatal_error(
-        Twine("Invalid register name \"" + StringRef(RegName) + "\"."));
+  if (!Reg)
+    return Reg;
   BitVector ReservedRegs = Subtarget.getRegisterInfo()->getReservedRegs(MF);
   if (!ReservedRegs.test(Reg))
     report_fatal_error(Twine("Trying to obtain non-reserved register \"" +

llvm/lib/Target/Mips/MipsISelLowering.cpp

@@ -4969,17 +4969,14 @@ MipsTargetLowering::getRegisterByName(const char *RegName, LLT VT,
                        .Case("$28", Mips::GP_64)
                        .Case("sp", Mips::SP_64)
                        .Default(Register());
-    if (Reg)
-      return Reg;
-  } else {
-    Register Reg = StringSwitch<Register>(RegName)
-                       .Case("$28", Mips::GP)
-                       .Case("sp", Mips::SP)
-                       .Default(Register());
-    if (Reg)
-      return Reg;
+    return Reg;
   }
-  report_fatal_error("Invalid register name global variable");
+
+  Register Reg = StringSwitch<Register>(RegName)
+                     .Case("$28", Mips::GP)
+                     .Case("sp", Mips::SP)
+                     .Default(Register());
+  return Reg;
 }
 
 MachineBasicBlock *MipsTargetLowering::emitLDR_W(MachineInstr &MI,

llvm/lib/Target/PowerPC/PPCISelLowering.cpp

@@ -17984,8 +17984,7 @@ Register PPCTargetLowering::getRegisterByName(const char *RegName, LLT VT,
 
   Register Reg = MatchRegisterName(RegName);
   if (!Reg)
-    report_fatal_error(
-        Twine("Invalid global name register \"" + StringRef(RegName) + "\"."));
+    return Reg;
 
   // FIXME: Unable to generate code for `-O2` but okay for `-O0`.
   // Need followup investigation as to why.