AMDPGU/R600: Replace llvm_unreachable() call with LLVMContext::emitError()

Summary:
This fixes an issue on MIPS where the infinite-loop-evergreen.ll test
was failing to terminate.

Fixes PR24147.

Reviewers: arsenm, dsanders

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D11260

llvm-svn: 242410

1 files changed, 3 insertions, 12 deletions

diff --git a/llvm/lib/Target/AMDGPU/AMDILCFGStructurizer.cpp b/llvm/lib/Target/AMDGPU/AMDILCFGStructurizer.cpp
index c9b25a1a0b8..9fa2bcd7eed 100644
--- a/llvm/lib/Target/AMDGPU/AMDILCFGStructurizer.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDILCFGStructurizer.cpp
@@ -1732,18 +1732,9 @@ AMDGPUCFGStructurizer::normalizeInfiniteLoopExit(MachineLoop* LoopRep) {
   FuncRep->push_back(DummyExitBlk);  //insert to function
   SHOWNEWBLK(DummyExitBlk, "DummyExitBlock to normalize infiniteLoop: ");
   DEBUG(dbgs() << "Old branch instr: " << *BranchMI << "\n";);
-  MachineBasicBlock::iterator I = BranchMI;
-  unsigned ImmReg = FuncRep->getRegInfo().createVirtualRegister(I32RC);
-  llvm_unreachable("Extra register needed to handle CFG");
-  MachineInstr *NewMI = insertInstrBefore(I, AMDGPU::BRANCH_COND_i32);
-  MachineInstrBuilder MIB(*FuncRep, NewMI);
-  MIB.addMBB(LoopHeader);
-  MIB.addReg(ImmReg, false);
-  SHOWNEWINSTR(NewMI);
-  BranchMI->eraseFromParent();
-  LoopLatch->addSuccessor(DummyExitBlk);
-
-  return DummyExitBlk;
+  LLVMContext &Ctx = LoopHeader->getParent()->getFunction()->getContext();
+  Ctx.emitError("Extra register needed to handle CFG");
+  return nullptr;
 }
 
 void AMDGPUCFGStructurizer::removeUnconditionalBranch(MachineBasicBlock *MBB) {