[GlobalIsel][X86] Support for llvm.trap intrinsic

[igorb]

LGTM

lib/Target/X86/X86InstructionSelector.cpp

bool selectTurnIntoCOPY(MachineInstr &I, MachineRegisterInfo &MRI,
                           const TargetRegisterClass *SrcRC) const;
   bool materializeFP(MachineInstr &I, MachineRegisterInfo &MRI,
                      MachineFunction &MF) const;
   bool selectImplicitDefOrPHI(MachineInstr &I, MachineRegisterInfo &MRI) const;
   bool selectShift(MachineInstr &I, MachineRegisterInfo &MRI,
                    MachineFunction &MF) const;
   bool selectSDiv(MachineInstr &I, MachineRegisterInfo &MRI,
                    MachineFunction &MF) const;
+  bool selectIntrinsicWSideEffects(MachineInstr &I, MachineRegisterInfo &MRI,
+                                   MachineFunction &MF) const;
 
   // emit insert subreg instruction and insert it before MachineInstr &I
   bool emitInsertSubreg(unsigned DstReg, unsigned SrcReg, MachineInstr &I,
                         MachineRegisterInfo &MRI, MachineFunction &MF) const;
   // emit extract subreg instruction and insert it before MachineInstr &I
   bool emitExtractSubreg(unsigned DstReg, unsigned SrcReg, MachineInstr &I,
                          MachineRegisterInfo &MRI, MachineFunction &MF) const;
 
bool X86InstructionSelector::select(MachineInstr &I,
   case TargetOpcode::G_PHI:
     return selectImplicitDefOrPHI(I, MRI);
   case TargetOpcode::G_SHL:
   case TargetOpcode::G_ASHR:
   case TargetOpcode::G_LSHR:
     return selectShift(I, MRI, MF);
   case TargetOpcode::G_SDIV:
     return selectSDiv(I, MRI, MF);
+  case TargetOpcode::G_INTRINSIC_W_SIDE_EFFECTS:
+    return selectIntrinsicWSideEffects(I, MRI, MF);
   }
 
   return false;
 }
 
 unsigned X86InstructionSelector::getLoadStoreOp(const LLT &Ty,
                                                 const RegisterBank &RB,
                                                 unsigned Opc,
bool X86InstructionSelector::selectSDiv(MachineInstr &I,
   BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(TargetOpcode::COPY),
           DstReg)
       .addReg(SDivEntryIt->QuotientReg);
 
   I.eraseFromParent();
   return true;
 }
 
+bool X86InstructionSelector::selectIntrinsicWSideEffects(
+    MachineInstr &I, MachineRegisterInfo &MRI, MachineFunction &MF) const {
+
+  assert(I.getOpcode() == TargetOpcode::G_INTRINSIC_W_SIDE_EFFECTS &&
+         "unexpected instruction");
+
+  if (I.getOperand(0).getIntrinsicID() != Intrinsic::trap)
+    return false;
+
+  BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(X86::TRAP));
+
+  I.eraseFromParent();
+  return true;
+}
+
 InstructionSelector *
 llvm::createX86InstructionSelector(const X86TargetMachine &TM,
                                    X86Subtarget &Subtarget,
                                    X86RegisterBankInfo &RBI) {
   return new X86InstructionSelector(TM, Subtarget, RBI);
 }

test/CodeGen/X86/GlobalISel/x86-select-trap.mir

+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=i386-linux-gnu -run-pass=instruction-select -verify-machineinstrs %s -o - | FileCheck %s
+
+--- |
+  declare void @llvm.trap() #0
+
+  define i32 @trap() #0 {
+    tail call void @llvm.trap()
+    unreachable
+  }
+
+  attributes #0 = { noreturn nounwind }
+  attributes #1 = { nounwind }
+
+...
+---
+name:            trap
+alignment:       4
+legalized:       true
+regBankSelected: true
+tracksRegLiveness: true
+body:             |
+  bb.1 (%ir-block.0):
+    ; CHECK-LABEL: name: trap
+    ; CHECK: TRAP
+    G_INTRINSIC_W_SIDE_EFFECTS intrinsic(@llvm.trap)
+
+...