Subzero: Translate the unreachable bitcode directly to ud2.

src/IceTargetLoweringX8632.cpp

 //===- subzero/src/IceTargetLoweringX8632.cpp - x86-32 lowering -----------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the TargetLoweringX8632 class, which
@@ skipping 4101 matching lines @@
         NextCast->getSrc(0) == SignExtendedResult) {
       NextCast->setDeleted();
       _movp(NextCast->getDest(), legalizeToVar(SignExtendedResult));
       // Skip over the instruction.
       Context.advanceNext();
     }
   }
 }
 
 void TargetX8632::lowerUnreachable(const InstUnreachable * /*Inst*/) {
-  const SizeT MaxSrcs = 0;
-  Variable *Dest = nullptr;
-  InstCall *Call = makeHelperCall("ice_unreachable", Dest, MaxSrcs);
-  lowerCall(Call);
+  _ud2();
 }
 
 // Turn an i64 Phi instruction into a pair of i32 Phi instructions, to
 // preserve integrity of liveness analysis.  Undef values are also
 // turned into zeroes, since loOperand() and hiOperand() don't expect
 // Undef input.
 void TargetX8632::prelowerPhis() {
   CfgNode *Node = Context.getNode();
   for (Inst &I : Node->getPhis()) {
     auto Phi = llvm::dyn_cast<InstPhi>(&I);
@@ skipping 635 matching lines @@
   case FT_Asm:
   case FT_Iasm: {
     OstreamLocker L(Ctx);
     emitConstantPool<PoolTypeConverter<float>>(Ctx);
     emitConstantPool<PoolTypeConverter<double>>(Ctx);
   } break;
   }
 }
 
 } // end of namespace Ice