[ARM][MachineOutliner] Add stack fixup feature.

[yroux]

Summary

This patch handles cases where we have to save/restore the link register into the stack and and load/store instruction which use the stack are part of the outlined region. It checks that there will be no overflow introduced by the new offset and fixup these instructions accordingly.

[yroux]

ping

[yroux]

ping

[samparker]

Sorry for the big delay Yvan, I haven't really been working on LLVM recently.

llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp

5899

How about extracting this out into ARMBaseInstrInfo? There seems to be a fair number of places in the backend where getting the NumBits and Scale comes up.

6375

Does this mean that we can call fixupPostOutline twice on MBB? I'm confused why we're checking for saving LR here, when it looks like we'd know for sure around line 6351.

[yroux]

Hi Sam,

no worries ;)

llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp

5899

Yes I was thinking of that kind of refactoring and I'll look at it, now if you are ok with that peace of code, what about committing it as it is such that we can have full version of the machine outliner in LLVM-12. And I'll propose a refactoring patch ASAP (since will touch BaseRegisterInfo, ConstantIsland, etc... I guess it will take some time to validate it properly)

6375

we have 2 cases where LR is saved on the stack and we need to fixup its access:

• when we have a call inside the outlined region, we are saving/restoring LR at the begining/end of this block, it is the case handled at line 6351
• but also, at call site when LR is read after the outlined region of one of the candidates for instance (this is the MachineOutlinerDefault mode) we have to fixup the stack access as well (this case)

[samparker]

LGTM

llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp

5899

Okay, sounds fair enough to me.

llvm/lib/Target/ARM/ARMBaseInstrInfo.h

private:
   /// after the LR is was restored from the stack.
   void emitCFIForLRRestoreFromStack(MachineBasicBlock &MBB,
                                     MachineBasicBlock::iterator It) const;
 
   /// Emit CFI instructions into the MachineBasicBlock \p MBB at position \p It,
   /// after the LR is was restored from a register.
   void emitCFIForLRRestoreFromReg(MachineBasicBlock &MBB,
                                   MachineBasicBlock::iterator It) const;
+  /// \brief Sets the offsets on outlined instructions in \p MBB which use SP
+  /// so that they will be valid post-outlining.
+  ///
+  /// \param MBB A \p MachineBasicBlock in an outlined function.
+  void fixupPostOutline(MachineBasicBlock &MBB) const;
+
+  /// Returns true if the machine instruction offset can handle the stack fixup
+  /// and updates it if requested.
+  bool checkAndUpdateStackOffset(MachineInstr *MI, int64_t Fixup,
+                                 bool Updt) const;
 
   unsigned getInstBundleLength(const MachineInstr &MI) const;
 
   int getVLDMDefCycle(const InstrItineraryData *ItinData,
                       const MCInstrDesc &DefMCID,
                       unsigned DefClass,
                       unsigned DefIdx, unsigned DefAlign) const;
   int getLDMDefCycle(const InstrItineraryData *ItinData,

llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp

else if (FrameID != MachineOutlinerThunk &&
              FrameID != MachineOutlinerTailCall && FirstCand.back()->isCall())
       NumBytesToCreateFrame += Costs.SaveRestoreLROnStack;
   }
 
   return outliner::OutlinedFunction(RepeatedSequenceLocs, SequenceSize,
                                     NumBytesToCreateFrame, FrameID);
 }
 
+bool ARMBaseInstrInfo::checkAndUpdateStackOffset(MachineInstr *MI,
+                                                 int64_t Fixup,
+                                                 bool Updt) const {
+  int SPIdx = MI->findRegisterUseOperandIdx(ARM::SP);
+  unsigned AddrMode = (MI->getDesc().TSFlags & ARMII::AddrModeMask);
+  if (SPIdx < 0)
+    // No SP operand
+    return true;
+  else if (SPIdx != 1 && (AddrMode != ARMII::AddrModeT2_i8s4 || SPIdx != 2))
+    // If SP is not the base register we can't do much
+    return false;
+
+  // Stack might be involved but addressing mode doesn't handle any offset.
+  // Rq: AddrModeT1_[1|2|4] don't operate on SP
+  if (AddrMode == ARMII::AddrMode1        // Arithmetic instructions
+      || AddrMode == ARMII::AddrMode4     // Load/Store Multiple
+      || AddrMode == ARMII::AddrMode6     // Neon Load/Store Multiple
+      || AddrMode == ARMII::AddrModeT2_so // SP can't be used as based register
+      || AddrMode == ARMII::AddrModeT2_pc // PCrel access
+      || AddrMode == ARMII::AddrMode2     // Used by PRE and POST indexed LD/ST
+      || AddrMode == ARMII::AddrModeNone)
+    return false;
+
+  unsigned NumOps = MI->getDesc().getNumOperands();
+  unsigned ImmIdx = NumOps - 3;
+
+  const MachineOperand &Offset = MI->getOperand(ImmIdx);
+  assert(Offset.isImm() && "Is not an immediate");
+  int64_t OffVal = Offset.getImm();
+
+  if (OffVal < 0)
+    // Don't override data if the are below SP.
+    return false;
+
+  unsigned NumBits = 0;
+  unsigned Scale = 1;
+
+  switch (AddrMode) {
+  case ARMII::AddrMode3:
+    if (ARM_AM::getAM3Op(OffVal) == ARM_AM::sub)
+      return false;
+    OffVal = ARM_AM::getAM3Offset(OffVal);
+    NumBits = 8;
+    break;
+  case ARMII::AddrMode5:
+    if (ARM_AM::getAM5Op(OffVal) == ARM_AM::sub)
+      return false;
+    OffVal = ARM_AM::getAM5Offset(OffVal);
+    NumBits = 8;
+    Scale = 4;
+    break;
+  case ARMII::AddrMode5FP16:
+    if (ARM_AM::getAM5FP16Op(OffVal) == ARM_AM::sub)
+      return false;
+    OffVal = ARM_AM::getAM5FP16Offset(OffVal);
+    NumBits = 8;
+    Scale = 2;
+    break;
+  case ARMII::AddrModeT2_i8:
+    NumBits = 8;
+    break;
+  case ARMII::AddrModeT2_i8s4:
+  case ARMII::AddrModeT2_ldrex:
+    NumBits = 8;
+    Scale = 4;
+    break;
+  case ARMII::AddrModeT2_i12:
+  case ARMII::AddrMode_i12:
+    NumBits = 12;
+    break;
+  case ARMII::AddrModeT2_i7:
+    NumBits = 7;
+    break;
+  case ARMII::AddrModeT2_i7s2:
+    NumBits = 7;
+    Scale = 2;
+    break;
+  case ARMII::AddrModeT2_i7s4:
+    NumBits = 7;
+    Scale = 4;
+    break;
+  case ARMII::AddrModeT1_s: // SP-relative LD/ST
+    NumBits = 8;
+    Scale = 4;
+    break;
+  default:
+    llvm_unreachable("Unsupported addressing mode!");
+  }
+  // Make sure the offset is encodable for instructions that scale the
+  // immediate.
+  if (((OffVal * Scale + Fixup) & (Scale - 1)) != 0)
+    return false;
+
+  OffVal += Fixup / Scale;
+
+  unsigned Mask = (1 << NumBits) - 1;
+
+  if (OffVal <= Mask) {
+    if (Updt)
+      MI->getOperand(ImmIdx).setImm(OffVal);
+    return true;
+  }
+
+  return false;
+
+}
+
 bool ARMBaseInstrInfo::isFunctionSafeToOutlineFrom(
     MachineFunction &MF, bool OutlineFromLinkOnceODRs) const {
   const Function &F = MF.getFunction();
 
   // Can F be deduplicated by the linker? If it can, don't outline from it.
   if (!OutlineFromLinkOnceODRs && F.hasLinkOnceODRLinkage())
     return false;
 
if (MI.modifiesRegister(ARM::SP, TRI) || MI.readsRegister(ARM::SP, TRI)) {
     // not just the bit we will try to outline.
     bool MightNeedStackFixUp =
         (Flags & (MachineOutlinerMBBFlags::LRUnavailableSomewhere |
                   MachineOutlinerMBBFlags::HasCalls));
 
     if (!MightNeedStackFixUp)
       return outliner::InstrType::Legal;
 
+    // Any modification of SP will break our code to save/restore LR.
+    // FIXME: We could handle some instructions which add a constant offset to
+    // SP, with a bit more work.
+    if (MI.modifiesRegister(ARM::SP, TRI))
+      return outliner::InstrType::Illegal;
+
+    // At this point, we have a stack instruction that we might need to fix up.
+    // up. We'll handle it if it's a load or store.
+    if (checkAndUpdateStackOffset(&MI, Subtarget.getStackAlignment().value(),
+                                  false))
+      return outliner::InstrType::Legal;
+
+    // We can't fix it up, so don't outline it.
     return outliner::InstrType::Illegal;
   }
 
   // Be conservative with IT blocks.
   if (MI.readsRegister(ARM::ITSTATE, TRI) ||
       MI.modifiesRegister(ARM::ITSTATE, TRI))
     return outliner::InstrType::Illegal;
 
   // Don't outline positions.
   if (MI.isPosition())
     return outliner::InstrType::Illegal;
 
   return outliner::InstrType::Legal;
 }
 
+void ARMBaseInstrInfo::fixupPostOutline(MachineBasicBlock &MBB) const {
+  for (MachineInstr &MI : MBB) {
+    checkAndUpdateStackOffset(&MI, Subtarget.getStackAlignment().value(), true);
+  }
+}
+
 void ARMBaseInstrInfo::saveLROnStack(MachineBasicBlock &MBB,
                                      MachineBasicBlock::iterator It) const {
   unsigned Opc = Subtarget.isThumb() ? ARM::t2STR_PRE : ARM::STR_PRE_IMM;
   int Align = -Subtarget.getStackAlignment().value();
   BuildMI(MBB, It, DebugLoc(), get(Opc), ARM::SP)
     .addReg(ARM::LR, RegState::Kill)
     .addReg(ARM::SP)
     .addImm(Align)
if (std::any_of(MBB.instr_begin(), MBB.instr_end(), IsNonTailCall)) {
     // functions only have one block.
     if (!MBB.isLiveIn(ARM::LR))
       MBB.addLiveIn(ARM::LR);
 
     // Insert a save before the outlined region
     saveLROnStack(MBB, It);
     emitCFIForLRSaveOnStack(MBB, It);
 
+    // Fix up the instructions in the range, since we're going to modify the
+    // stack.
+    assert(OF.FrameConstructionID != MachineOutlinerDefault &&
+           "Can only fix up stack references once");
+    fixupPostOutline(MBB);
+
     // Insert a restore before the terminator for the function.  Restore LR.
     restoreLRFromStack(MBB, Et);
     emitCFIForLRRestoreFromStack(MBB, Et);
   }
 
   // If this is a tail call outlined function, then there's already a return.
   if (OF.FrameConstructionID == MachineOutlinerTailCall ||
       OF.FrameConstructionID == MachineOutlinerThunk)
     return;
 
   // Here we have to insert the return ourselves.  Get the correct opcode from
   // current feature set.
   BuildMI(MBB, MBB.end(), DebugLoc(), get(Subtarget.getReturnOpcode()))
       .add(predOps(ARMCC::AL));
+
+  // Did we have to modify the stack by saving the link register?
+  if (OF.FrameConstructionID != MachineOutlinerDefault &&
+      OF.Candidates[0].CallConstructionID != MachineOutlinerDefault)
+    return;
+
+  // We modified the stack.
+  // Walk over the basic block and fix up all the stack accesses.
+  fixupPostOutline(MBB);
 }
 
 MachineBasicBlock::iterator ARMBaseInstrInfo::insertOutlinedCall(
     Module &M, MachineBasicBlock &MBB, MachineBasicBlock::iterator &It,
     MachineFunction &MF, const outliner::Candidate &C) const {
   MachineInstrBuilder MIB;
   MachineBasicBlock::iterator CallPt;
   unsigned Opc;
if (C.CallConstructionID == MachineOutlinerRegSave) {
     CallPt = MBB.insert(It, CallMIB);
     copyPhysReg(MBB, It, DebugLoc(), ARM::LR, Reg, true);
     if (!AFI.isLRSpilled())
       emitCFIForLRRestoreFromReg(MBB, It);
     It--;
     return CallPt;
   }
   // We have the default case. Save and restore from SP.
+  if (!MBB.isLiveIn(ARM::LR))
+    MBB.addLiveIn(ARM::LR);
   saveLROnStack(MBB, It);
   if (!AFI.isLRSpilled())
     emitCFIForLRSaveOnStack(MBB, It);
   CallPt = MBB.insert(It, CallMIB);
   restoreLRFromStack(MBB, It);
   if (!AFI.isLRSpilled())
     emitCFIForLRRestoreFromStack(MBB, It);
   It--;

llvm/test/CodeGen/ARM/machine-outliner-default.mir

 # NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
 # RUN: llc -mtriple=arm-- -run-pass=machine-outliner -verify-machineinstrs \
 # RUN: %s -o - | FileCheck %s
 
 --- |
   define void @outline_default_arm() #0 { ret void }
   define void @outline_default_thumb() #1 { ret void }
-  define void @outline_default_KO_stack_arm() #0 { ret void }
-  define void @outline_default_KO_stack_thumb() #0 { ret void }
   declare void @bar()
 
   attributes #0 = { minsize optsize }
   attributes #1 = { minsize optsize "target-features"="+armv7-a,+thumb-mode" }
 ...
 ---
 
 name:           outline_default_arm
bb.2:
     $r0 = t2MOVi 1, 14, $noreg, $noreg
     $r1 = t2MOVi 1, 14, $noreg, $noreg
     $r2 = t2MOVi 1, 14, $noreg, $noreg
     $r3 = t2MOVi 1, 14, $noreg, $noreg
   bb.3:
     liveins: $lr, $r4, $r5, $r6, $r7, $r8, $r9, $r10, $r11
     $r2 = tMOVr $lr, 14, $noreg
     tBX_RET 14, $noreg
-...
----
-
-name:           outline_default_KO_stack_arm
-tracksRegLiveness: true
-body:             |
-  ; CHECK-LABEL: name: outline_default_KO_stack_arm
-  ; CHECK: bb.0:
-  ; CHECK:   liveins: $lr
-  ; CHECK:   $r0 = LDRi12 $sp, 0, 14 /* CC::al */, $noreg
-  ; CHECK:   $r1 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r2 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r3 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r4 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r5 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK: bb.1:
-  ; CHECK:   liveins: $lr, $r6, $r7, $r8, $r9, $r10, $r11
-  ; CHECK:   $r0 = LDRi12 $sp, 0, 14 /* CC::al */, $noreg
-  ; CHECK:   $r1 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r2 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r3 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r4 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r5 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK: bb.2:
-  ; CHECK:   liveins: $lr, $r5, $r6, $r7, $r8, $r9, $r10, $r11
-  ; CHECK:   $r0 = LDRi12 $sp, 0, 14 /* CC::al */, $noreg
-  ; CHECK:   $r1 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r2 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r3 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r4 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r5 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK: bb.3:
-  ; CHECK:   liveins: $lr, $r5, $r6, $r7, $r8, $r9, $r10, $r11
-  ; CHECK:   $r2 = MOVr $lr, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   BX_RET 14 /* CC::al */, $noreg
-  bb.0:
-    liveins: $lr
-    $r0 = LDRi12 $sp, 0, 14, $noreg
-    $r1 = MOVi 3, 14, $noreg, $noreg
-    $r2 = MOVi 3, 14, $noreg, $noreg
-    $r3 = MOVi 3, 14, $noreg, $noreg
-    $r4 = MOVi 3, 14, $noreg, $noreg
-    $r5 = MOVi 3, 14, $noreg, $noreg
-  bb.1:
-    liveins: $lr, $r6, $r7, $r8, $r9, $r10, $r11
-    $r0 = LDRi12 $sp, 0, 14, $noreg
-    $r1 = MOVi 3, 14, $noreg, $noreg
-    $r2 = MOVi 3, 14, $noreg, $noreg
-    $r3 = MOVi 3, 14, $noreg, $noreg
-    $r4 = MOVi 3, 14, $noreg, $noreg
-    $r5 = MOVi 3, 14, $noreg, $noreg
-  bb.2:
-    liveins: $lr, $r5, $r6, $r7, $r8, $r9, $r10, $r11
-    $r0 = LDRi12 $sp, 0, 14, $noreg
-    $r1 = MOVi 3, 14, $noreg, $noreg
-    $r2 = MOVi 3, 14, $noreg, $noreg
-    $r3 = MOVi 3, 14, $noreg, $noreg
-    $r4 = MOVi 3, 14, $noreg, $noreg
-    $r5 = MOVi 3, 14, $noreg, $noreg
-  bb.3:
-    liveins: $lr, $r5, $r6, $r7, $r8, $r9, $r10, $r11
-    $r2 = MOVr $lr, 14, $noreg, $noreg
-    BX_RET 14, $noreg
-...
----
-
-name:           outline_default_KO_stack_thumb
-tracksRegLiveness: true
-body:             |
-  ; CHECK-LABEL: name: outline_default_KO_stack_thumb
-  ; CHECK: bb.0:
-  ; CHECK:   liveins: $lr
-  ; CHECK:   $r0 = t2LDRi12 $sp, 0, 14 /* CC::al */, $noreg
-  ; CHECK:   $r1 = t2MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r2 = t2MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r3 = t2MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK: bb.1:
-  ; CHECK:   liveins: $lr, $r4, $r5, $r6, $r7, $r8, $r9, $r10, $r11
-  ; CHECK:   $r0 = t2LDRi12 $sp, 0, 14 /* CC::al */, $noreg
-  ; CHECK:   $r1 = t2MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r2 = t2MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r3 = t2MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK: bb.2:
-  ; CHECK:   liveins: $lr, $r4, $r5, $r6, $r7, $r8, $r9, $r10, $r11
-  ; CHECK:   $r0 = t2LDRi12 $sp, 0, 14 /* CC::al */, $noreg
-  ; CHECK:   $r1 = t2MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r2 = t2MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r3 = t2MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK: bb.3:
-  ; CHECK:   liveins: $lr, $r4, $r5, $r6, $r7, $r8, $r9, $r10, $r11
-  ; CHECK:   $r2 = tMOVr $lr, 14 /* CC::al */, $noreg
-  ; CHECK:   tBX_RET 14 /* CC::al */, $noreg
-  bb.0:
-    liveins: $lr
-    $r0 = t2LDRi12 $sp, 0, 14, $noreg
-    $r1 = t2MOVi 3, 14, $noreg, $noreg
-    $r2 = t2MOVi 3, 14, $noreg, $noreg
-    $r3 = t2MOVi 3, 14, $noreg, $noreg
-  bb.1:
-    liveins: $lr, $r4, $r5, $r6, $r7, $r8, $r9, $r10, $r11
-    $r0 = t2LDRi12 $sp, 0, 14, $noreg
-    $r1 = t2MOVi 3, 14, $noreg, $noreg
-    $r2 = t2MOVi 3, 14, $noreg, $noreg
-    $r3 = t2MOVi 3, 14, $noreg, $noreg
-  bb.2:
-    liveins: $lr, $r4, $r5, $r6, $r7, $r8, $r9, $r10, $r11
-    $r0 = t2LDRi12 $sp, 0, 14, $noreg
-    $r1 = t2MOVi 3, 14, $noreg, $noreg
-    $r2 = t2MOVi 3, 14, $noreg, $noreg
-    $r3 = t2MOVi 3, 14, $noreg, $noreg
-  bb.3:
-    liveins: $lr, $r4, $r5, $r6, $r7, $r8, $r9, $r10, $r11
-    $r2 = tMOVr $lr, 14, $noreg
-    tBX_RET 14, $noreg
-
 
   ; CHECK-LABEL: name: OUTLINED_FUNCTION_0
   ; CHECK: bb.0:
   ; CHECK:   liveins: $lr, $r6, $r7, $r8, $r9, $r10, $r11
   ; CHECK:   $r0 = MOVi 1, 14 /* CC::al */, $noreg, $noreg
   ; CHECK:   $r1 = MOVi 1, 14 /* CC::al */, $noreg, $noreg
   ; CHECK:   $r2 = MOVi 1, 14 /* CC::al */, $noreg, $noreg
   ; CHECK:   $r3 = MOVi 1, 14 /* CC::al */, $noreg, $noreg

llvm/test/CodeGen/ARM/machine-outliner-no-lr-save.mir

 # NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
 # RUN: llc -mtriple=arm-- -run-pass=machine-outliner -verify-machineinstrs \
 # RUN: %s -o - | FileCheck %s
 
 --- |
   define void @outline_no_save_ok_arm() #0 { ret void }
-  define void @outline_no_save_ko_arm() #0 { ret void }
   define void @outline_no_save_ok_thumb() #1 { ret void }
-  define void @outline_no_save_ko_thumb() #1 { ret void }
 
   declare void @foo()
 
   attributes #0 = { minsize optsize }
   attributes #1 = { minsize optsize "target-features"="+armv7-a,+thumb-mode" }
 ...
 ---
 
bb.1:
     $r2 = MOVi 1, 14, $noreg, $noreg
     $r2 = MOVi 1, 14, $noreg, $noreg
     $r3 = LDRi12 $sp, 8, 14, $noreg
   bb.2:
     BX_RET 14, $noreg
 ...
 ---
 
-name:           outline_no_save_ko_arm
-tracksRegLiveness: true
-body:             |
-  ; CHECK-LABEL: name: outline_no_save_ko_arm
-  ; CHECK-NOT: OUTLINED_FUNCTION
-  bb.0:
-    liveins: $lr
-    $r2 = MOVi 2, 14, $noreg, $noreg
-    $r2 = MOVi 2, 14, $noreg, $noreg
-    $r2 = MOVi 2, 14, $noreg, $noreg
-    $r2 = MOVi 2, 14, $noreg, $noreg
-    $r3 = LDRi12 $sp, 8, 14, $noreg
-    $r2 = MOVr $lr, 14, $noreg, $noreg
-  bb.1:
-    $r2 = MOVi 2, 14, $noreg, $noreg
-    $r2 = MOVi 2, 14, $noreg, $noreg
-    $r2 = MOVi 2, 14, $noreg, $noreg
-    $r2 = MOVi 2, 14, $noreg, $noreg
-    $r3 = LDRi12 $sp, 8, 14, $noreg
-    $r4 = MOVi 4, 14, $noreg, $noreg
-    BL @foo
-  bb.2:
-    liveins: $lr
-    BX_RET 14, $noreg
-...
----
-
 name:           outline_no_save_ok_thumb
 tracksRegLiveness: true
 body:             |
   ; CHECK-LABEL: name: outline_no_save_ok_thumb
   ; CHECK: bb.0:
   ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_0
   ; CHECK: bb.1:
   ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_0
   ; CHECK: bb.2:
   ; CHECK:   tBX_RET 14 /* CC::al */, $noreg
   bb.0:
     $r2 = t2MOVi 1, 14, $noreg, $noreg
     $r2 = t2MOVi 1, 14, $noreg, $noreg
     $r2 = t2MOVi 1, 14, $noreg, $noreg
     $r2 = t2MOVi 1, 14, $noreg, $noreg
     t2STRi12 $r2, $sp, 0, 14, $noreg
   bb.1:
     $r2 = t2MOVi 1, 14, $noreg, $noreg
     $r2 = t2MOVi 1, 14, $noreg, $noreg
     $r2 = t2MOVi 1, 14, $noreg, $noreg
     $r2 = t2MOVi 1, 14, $noreg, $noreg
     t2STRi12 $r2, $sp, 0, 14, $noreg
   bb.2:
     tBX_RET 14, $noreg
-...
----
-
-name:           outline_no_save_ko_thumb
-tracksRegLiveness: true
-body:             |
-  ; CHECK-LABEL: name: outline_no_save_ko_thumb
-  ; CHECK-NOT: OUTLINED_FUNCTION
-  bb.0:
-    liveins: $lr
-    $r2 = t2MOVi 2, 14, $noreg, $noreg
-    $r2 = t2MOVi 2, 14, $noreg, $noreg
-    $r2 = t2MOVi 2, 14, $noreg, $noreg
-    $r2 = t2MOVi 2, 14, $noreg, $noreg
-    t2STRi12 $r2, $sp, 0, 14, $noreg
-    $r2 = tMOVr $lr, 14, $noreg
-  bb.1:
-    $r2 = t2MOVi 2, 14, $noreg, $noreg
-    $r2 = t2MOVi 2, 14, $noreg, $noreg
-    $r2 = t2MOVi 2, 14, $noreg, $noreg
-    $r2 = t2MOVi 2, 14, $noreg, $noreg
-    t2STRi12 $r2, $sp, 0, 14, $noreg
-    $r4 = t2MOVi 3, 14, $noreg, $noreg
-    tBL 14, $noreg, @foo
-  bb.2:
-    liveins: $lr, $r0, $r6, $r7, $r8, $r9, $r10, $r11
-    tBX_RET 14, $noreg
 
   ; CHECK-LABEL: name: OUTLINED_FUNCTION_0
   ; CHECK: bb.0:
   ; CHECK:   $r2 = t2MOVi 1, 14 /* CC::al */, $noreg, $noreg
   ; CHECK:   $r2 = t2MOVi 1, 14 /* CC::al */, $noreg, $noreg
   ; CHECK:   $r2 = t2MOVi 1, 14 /* CC::al */, $noreg, $noreg
   ; CHECK:   $r2 = t2MOVi 1, 14 /* CC::al */, $noreg, $noreg
   ; CHECK:   t2STRi12 $r2, $sp, 0, 14 /* CC::al */, $noreg

llvm/test/CodeGen/ARM/machine-outliner-stack-fixup-arm.mir

+# RUN: llc -mtriple=armv7-- -run-pass=prologepilog -run-pass=machine-outliner \
+# RUN: -verify-machineinstrs %s -o - | FileCheck %s
+
+--- |
+  define void @CheckAddrMode_i12() { ret void }
+  define void @CheckAddrMode3() { ret void }
+  define void @CheckAddrMode5() { ret void }
+  define void @CheckAddrMode5FP16() { ret void }
+  define void @foo() { ret void }
+
+...
+---
+
+name:           CheckAddrMode_i12
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $r0
+    ; CHECK-LABEL: name:           CheckAddrMode_i12
+    ; CHECK: $r1 = MOVr killed $r0, 14 /* CC::al */, $noreg, $noreg
+    ; CHECK-NEXT: BL @OUTLINED_FUNCTION_[[I12:[0-9]+]]
+    ; CHECK-NEXT: $r6 = LDRi12 $sp, 4088, 14 /* CC::al */, $noreg
+    $r1 = MOVr killed $r0, 14, $noreg, $noreg
+    BL @foo, implicit-def dead $lr, implicit $sp
+    $r1 = LDRi12 $sp, 0, 14, $noreg
+    $r2 = LDRi12 $sp, 8, 14, $noreg
+    $r5 = LDRi12 $sp, 4086, 14, $noreg
+    $r6 = LDRi12 $sp, 4088, 14, $noreg
+    BL @foo, implicit-def dead $lr, implicit $sp
+    $r1 = LDRi12 $sp, 0, 14, $noreg
+    $r2 = LDRi12 $sp, 8, 14, $noreg
+    $r5 = LDRi12 $sp, 4086, 14, $noreg
+    $r6 = LDRi12 $sp, 4088, 14, $noreg
+    BL @foo, implicit-def dead $lr, implicit $sp
+    $r1 = LDRi12 $sp, 0, 14, $noreg
+    $r2 = LDRi12 $sp, 8, 14, $noreg
+    $r5 = LDRi12 $sp, 4086, 14, $noreg
+    $r6 = LDRi12 $sp, 4088, 14, $noreg
+    BX_RET 14, $noreg
+...
+---
+
+name:           CheckAddrMode3
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $r1
+    ; CHECK-LABEL: name:           CheckAddrMode3
+    ; CHECK: $r0 = MOVr killed $r1, 14 /* CC::al */, $noreg, $noreg
+    ; CHECK-NEXT: BL @OUTLINED_FUNCTION_[[I3:[0-9]+]]
+    ; CHECK-NEXT: $r6 = LDRSH $sp, $noreg, 248, 14 /* CC::al */, $noreg
+    $r0 = MOVr killed $r1, 14, $noreg, $noreg
+    BL @foo, implicit-def dead $lr, implicit $sp
+    $r1 = LDRSH $sp, $noreg, 0, 14, $noreg
+    $r2 = LDRSH $sp, $noreg, 8, 14, $noreg
+    $r5 = LDRSH $sp, $noreg, 247, 14, $noreg
+    $r6 = LDRSH $sp, $noreg, 248, 14, $noreg
+    BL @foo, implicit-def dead $lr, implicit $sp
+    $r1 = LDRSH $sp, $noreg, 0, 14, $noreg
+    $r2 = LDRSH $sp, $noreg, 8, 14, $noreg
+    $r5 = LDRSH $sp, $noreg, 247, 14, $noreg
+    $r6 = LDRSH $sp, $noreg, 248, 14, $noreg
+    BL @foo, implicit-def dead $lr, implicit $sp
+    $r1 = LDRSH $sp, $noreg, 0, 14, $noreg
+    $r2 = LDRSH $sp, $noreg, 8, 14, $noreg
+    $r5 = LDRSH $sp, $noreg, 247, 14, $noreg
+    $r6 = LDRSH $sp, $noreg, 248, 14, $noreg
+    BX_RET 14, $noreg
+...
+---
+
+name:           CheckAddrMode5
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $r2
+    ; CHECK-LABEL: name:           CheckAddrMode5
+    ; CHECK: $r0 = MOVr killed $r2, 14 /* CC::al */, $noreg, $noreg
+    ; CHECK-NEXT: BL @OUTLINED_FUNCTION_[[I5:[0-9]+]]
+    ; CHECK-NEXT: $d5 = VLDRD $sp, 254, 14 /* CC::al */, $noreg
+    $r0 = MOVr killed $r2, 14, $noreg, $noreg
+    BL @foo, implicit-def dead $lr, implicit $sp
+    $d0 = VLDRD $sp, 0, 14, $noreg
+    $d1 = VLDRD $sp, 8, 14, $noreg
+    $d4 = VLDRD $sp, 253, 14, $noreg
+    $d5 = VLDRD $sp, 254, 14, $noreg
+    BL @foo, implicit-def dead $lr, implicit $sp
+    $d0 = VLDRD $sp, 0, 14, $noreg
+    $d1 = VLDRD $sp, 8, 14, $noreg
+    $d4 = VLDRD $sp, 253, 14, $noreg
+    $d5 = VLDRD $sp, 254, 14, $noreg
+    BL @foo, implicit-def dead $lr, implicit $sp
+    $d0 = VLDRD $sp, 0, 14, $noreg
+    $d1 = VLDRD $sp, 8, 14, $noreg
+    $d4 = VLDRD $sp, 253, 14, $noreg
+    $d5 = VLDRD $sp, 254, 14, $noreg
+    BL @foo, implicit-def dead $lr, implicit $sp
+    $d0 = VLDRD $sp, 0, 14, $noreg
+    $d1 = VLDRD $sp, 8, 14, $noreg
+    $d4 = VLDRD $sp, 253, 14, $noreg
+    $d5 = VLDRD $sp, 254, 14, $noreg
+    BX_RET 14, $noreg
+...
+---
+
+name:           CheckAddrMode5FP16
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $r3
+    ; CHECK-LABEL: name:           CheckAddrMode5FP16
+    ; CHECK: $r0 = MOVr killed $r3, 14 /* CC::al */, $noreg, $noreg
+    ; CHECK-NEXT: BL @OUTLINED_FUNCTION_[[I5FP16:[0-9]+]]
+    ; CHECK-NEXT: $s6 = VLDRH $sp, 252, 14, $noreg
+    $r0 = MOVr killed $r3, 14, $noreg, $noreg
+    BL @foo, implicit-def dead $lr, implicit $sp
+    $s1 = VLDRH $sp, 0, 14, $noreg
+    $s2 = VLDRH $sp, 8, 14, $noreg
+    $s5 = VLDRH $sp, 240, 14, $noreg
+    $s6 = VLDRH $sp, 252, 14, $noreg
+    BL @foo, implicit-def dead $lr, implicit $sp
+    $s1 = VLDRH $sp, 0, 14, $noreg
+    $s2 = VLDRH $sp, 8, 14, $noreg
+    $s5 = VLDRH $sp, 240, 14, $noreg
+    $s6 = VLDRH $sp, 252, 14, $noreg
+    BL @foo, implicit-def dead $lr, implicit $sp
+    $s1 = VLDRH $sp, 0, 14, $noreg
+    $s2 = VLDRH $sp, 8, 14, $noreg
+    $s5 = VLDRH $sp, 240, 14, $noreg
+    $s6 = VLDRH $sp, 252, 14, $noreg
+    BL @foo, implicit-def dead $lr, implicit $sp
+    $s1 = VLDRH $sp, 0, 14, $noreg
+    $s2 = VLDRH $sp, 8, 14, $noreg
+    $s5 = VLDRH $sp, 240, 14, $noreg
+    $s6 = VLDRH $sp, 252, 14, $noreg
+    BX_RET 14, $noreg
+...
+---
+
+name:           foo
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $lr
+
+    BX_RET 14, $noreg
+
+    ;CHECK: name:           OUTLINED_FUNCTION_[[I5]]
+    ;CHECK: early-clobber $sp = STR_PRE_IMM killed $lr, $sp, -8, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: frame-setup CFI_INSTRUCTION def_cfa_offset 8
+    ;CHECK-NEXT: frame-setup CFI_INSTRUCTION offset $lr, -8
+    ;CHECK-NEXT: BL @foo, implicit-def dead $lr, implicit $sp
+    ;CHECK-NEXT: $d0 = VLDRD $sp, 2, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $d1 = VLDRD $sp, 10, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $d4 = VLDRD $sp, 255, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $lr, $sp = LDR_POST_IMM $sp, $noreg, 8, 14 /* CC::al */, $noreg
+
+    ;CHECK: name:           OUTLINED_FUNCTION_[[I5FP16]]
+    ;CHECK: early-clobber $sp = STR_PRE_IMM killed $lr, $sp, -8, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: frame-setup CFI_INSTRUCTION def_cfa_offset 8
+    ;CHECK-NEXT: frame-setup CFI_INSTRUCTION offset $lr, -8
+    ;CHECK-NEXT: BL @foo, implicit-def dead $lr, implicit $sp
+    ;CHECK-NEXT: $s1 = VLDRH $sp, 4, 14, $noreg
+    ;CHECK-NEXT: $s2 = VLDRH $sp, 12, 14, $noreg
+    ;CHECK-NEXT: $s5 = VLDRH $sp, 244, 14, $noreg
+    ;CHECK-NEXT: $lr, $sp = LDR_POST_IMM $sp, $noreg, 8, 14 /* CC::al */, $noreg
+
+    ;CHECK: name:           OUTLINED_FUNCTION_[[I12]]
+    ;CHECK: early-clobber $sp = STR_PRE_IMM killed $lr, $sp, -8, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: frame-setup CFI_INSTRUCTION def_cfa_offset 8
+    ;CHECK-NEXT: frame-setup CFI_INSTRUCTION offset $lr, -8
+    ;CHECK-NEXT: BL @foo, implicit-def dead $lr, implicit $sp
+    ;CHECK-NEXT: $r1 = LDRi12 $sp, 8, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $r2 = LDRi12 $sp, 16, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $r5 = LDRi12 $sp, 4094, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $lr, $sp = LDR_POST_IMM $sp, $noreg, 8, 14 /* CC::al */, $noreg
+
+    ;CHECK: name:           OUTLINED_FUNCTION_[[I3]]
+    ;CHECK: early-clobber $sp = STR_PRE_IMM killed $lr, $sp, -8, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: frame-setup CFI_INSTRUCTION def_cfa_offset 8
+    ;CHECK-NEXT: frame-setup CFI_INSTRUCTION offset $lr, -8
+    ;CHECK-NEXT: BL @foo, implicit-def dead $lr, implicit $sp
+    ;CHECK-NEXT: $r1 = LDRSH $sp, $noreg, 8, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $r2 = LDRSH $sp, $noreg, 16, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $r5 = LDRSH $sp, $noreg, 255, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $lr, $sp = LDR_POST_IMM $sp, $noreg, 8, 14 /* CC::al */, $noreg

llvm/test/CodeGen/ARM/machine-outliner-stack-fixup-thumb.mir

+# RUN: llc -mtriple=thumbv7-- -run-pass=prologepilog \
+# RUN: -run-pass=machine-outliner %s -o - | FileCheck %s
+
+--- |
+  define void @CheckAddrModeT2_i12() { ret void }
+  define void @CheckAddrModeT2_i8() { ret void }
+  define void @CheckAddrModeT2_i8s4() { ret void }
+  define void @CheckAddrModeT2_ldrex() { ret void }
+  define void @CheckAddrModeT1_s() { ret void }
+  define void @foo() { ret void }
+
+...
+---
+
+name:           CheckAddrModeT2_i12
+tracksRegLiveness: true
+
+body:             |
+  bb.0:
+    liveins: $r1
+    ;CHECK-LABEL: name:           CheckAddrModeT2_i12
+    ;CHECK: $r0 = tMOVr killed $r1, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_[[I12:[0-9]+]]
+    ;CHECK-NEXT: $r0 = t2LDRi12 $sp, 4088, 14 /* CC::al */, $noreg
+    $r0 = tMOVr killed $r1, 14, $noreg
+    tBL 14, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    $r0 = t2LDRi12 $sp, 0, 14, $noreg
+    $r0 = t2LDRi12 $sp, 4, 14, $noreg
+    $r0 = t2LDRi12 $sp, 4086, 14, $noreg
+    $r0 = t2LDRi12 $sp, 4088, 14, $noreg
+    tBL 14, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    $r0 = t2LDRi12 $sp, 0, 14, $noreg
+    $r0 = t2LDRi12 $sp, 4, 14, $noreg
+    $r0 = t2LDRi12 $sp, 4086, 14, $noreg
+    $r0 = t2LDRi12 $sp, 4088, 14, $noreg
+    tBL 14, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    $r0 = t2LDRi12 $sp, 0, 14, $noreg
+    $r0 = t2LDRi12 $sp, 4, 14, $noreg
+    $r0 = t2LDRi12 $sp, 4086, 14, $noreg
+    $r0 = t2LDRi12 $sp, 4088, 14, $noreg
+    BX_RET 14, $noreg
+...
+---
+
+name:           CheckAddrModeT2_i8
+tracksRegLiveness: true
+
+body:             |
+  bb.0:
+    liveins: $r1
+    ;CHECK-LABEL: name:           CheckAddrModeT2_i8
+    ;CHECK: $r0 = tMOVr $r1, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_[[I8:[0-9]+]]
+    ;CHECK-NEXT: t2STRHi8 $r0, $sp, 248, 14 /* CC::al */, $noreg
+    $r0 = tMOVr $r1, 14, $noreg
+    tBL 14, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    t2STRHi8 $r0, $sp, 0, 14, $noreg
+    t2STRHi8 $r0, $sp, 4, 14, $noreg
+    t2STRHi8 $r0, $sp, 247, 14, $noreg
+    t2STRHi8 $r0, $sp, 248, 14, $noreg
+    tBL 14, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    t2STRHi8 $r0, $sp, 0, 14, $noreg
+    t2STRHi8 $r0, $sp, 4, 14, $noreg
+    t2STRHi8 $r0, $sp, 247, 14, $noreg
+    t2STRHi8 $r0, $sp, 248, 14, $noreg
+    tBL 14, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    t2STRHi8 $r0, $sp, 0, 14, $noreg
+    t2STRHi8 $r0, $sp, 4, 14, $noreg
+    t2STRHi8 $r0, $sp, 247, 14, $noreg
+    t2STRHi8 $r0, $sp, 248, 14, $noreg
+    BX_RET 14, $noreg
+...
+---
+
+name:           CheckAddrModeT2_i8s4
+tracksRegLiveness: true
+
+body:             |
+  bb.0:
+    liveins: $r1
+    ;CHECK-LABEL: name:           CheckAddrModeT2_i8s4
+    ;CHECK: $r0 = tMOVr $r1, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_[[I8S4:[0-9]+]]
+    ;CHECK-NEXT: t2STRDi8 $r0, $r1, $sp, 254, 14 /* CC::al */, $noreg
+    $r0 = tMOVr $r1, 14, $noreg
+    tBL 14, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    t2STRDi8 $r0, $r1, $sp, 0, 14, $noreg
+    t2STRDi8 $r0, $r1, $sp, 8, 14, $noreg
+    t2STRDi8 $r0, $r1, $sp, 253, 14, $noreg
+    t2STRDi8 $r0, $r1, $sp, 254, 14, $noreg
+    tBL 14, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    t2STRDi8 $r0, $r1, $sp, 0, 14, $noreg
+    t2STRDi8 $r0, $r1, $sp, 8, 14, $noreg
+    t2STRDi8 $r0, $r1, $sp, 253, 14, $noreg
+    t2STRDi8 $r0, $r1, $sp, 254, 14, $noreg
+    tBL 14, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    t2STRDi8 $r0, $r1, $sp, 0, 14, $noreg
+    t2STRDi8 $r0, $r1, $sp, 8, 14, $noreg
+    t2STRDi8 $r0, $r1, $sp, 253, 14, $noreg
+    t2STRDi8 $r0, $r1, $sp, 254, 14, $noreg
+    BX_RET 14, $noreg
+...
+---
+
+name:           CheckAddrModeT2_ldrex
+tracksRegLiveness: true
+
+body:             |
+  bb.0:
+    liveins: $r1
+    ;CHECK-LABEL: name:           CheckAddrModeT2_ldrex
+    ;CHECK: $r0 = tMOVr $r1, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_[[LDREX:[0-9]+]]
+    ;CHECK-NEXT: $r1 = t2LDREX $sp, 254, 14 /* CC::al */, $noreg
+    $r0 = tMOVr $r1, 14, $noreg
+    tBL 14, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    $r1 = t2LDREX $sp, 0, 14, $noreg
+    $r1 = t2LDREX $sp, 8, 14, $noreg
+    $r1 = t2LDREX $sp, 253, 14, $noreg
+    $r1 = t2LDREX $sp, 254, 14, $noreg
+    tBL 14, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    $r1 = t2LDREX $sp, 0, 14, $noreg
+    $r1 = t2LDREX $sp, 8, 14, $noreg
+    $r1 = t2LDREX $sp, 253, 14, $noreg
+    $r1 = t2LDREX $sp, 254, 14, $noreg
+    tBL 14, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    $r1 = t2LDREX $sp, 0, 14, $noreg
+    $r1 = t2LDREX $sp, 8, 14, $noreg
+    $r1 = t2LDREX $sp, 253, 14, $noreg
+    $r1 = t2LDREX $sp, 254, 14, $noreg
+    tBL 14, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    $r1 = t2LDREX $sp, 0, 14, $noreg
+    $r1 = t2LDREX $sp, 8, 14, $noreg
+    $r1 = t2LDREX $sp, 253, 14, $noreg
+    $r1 = t2LDREX $sp, 254, 14, $noreg
+    BX_RET 14, $noreg
+...
+---
+
+name:           CheckAddrModeT1_s
+tracksRegLiveness: true
+
+body:             |
+  bb.0:
+    liveins: $r0, $r1
+    ;CHECK-LABEL: name:           CheckAddrModeT1_s
+    ;CHECK: $r0 = tMOVr $r1, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_[[T1_S:[0-9]+]]
+    ;CHECK-NEXT: tSTRspi $r0, $sp, 254, 14 /* CC::al */, $noreg
+    $r0 = tMOVr $r1, 14, $noreg
+    tBL 14, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    tSTRspi $r0, $sp, 0, 14, $noreg
+    tSTRspi $r0, $sp, 4, 14, $noreg
+    tSTRspi $r0, $sp, 253, 14, $noreg
+    tSTRspi $r0, $sp, 254, 14, $noreg
+    tBL 14, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    tSTRspi $r0, $sp, 0, 14, $noreg
+    tSTRspi $r0, $sp, 4, 14, $noreg
+    tSTRspi $r0, $sp, 253, 14, $noreg
+    tSTRspi $r0, $sp, 254, 14, $noreg
+    tBL 14, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    tSTRspi $r0, $sp, 0, 14, $noreg
+    tSTRspi $r0, $sp, 4, 14, $noreg
+    tSTRspi $r0, $sp, 253, 14, $noreg
+    tSTRspi $r0, $sp, 254, 14, $noreg
+    tBL 14, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    tSTRspi $r0, $sp, 0, 14, $noreg
+    tSTRspi $r0, $sp, 4, 14, $noreg
+    tSTRspi $r0, $sp, 253, 14, $noreg
+    tSTRspi $r0, $sp, 254, 14, $noreg
+    BX_RET 14, $noreg
+...
+---
+
+name:           foo
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $lr
+
+    BX_RET 14, $noreg
+
+    ;CHECK: name:           OUTLINED_FUNCTION_[[LDREX]]
+    ;CHECK: early-clobber $sp = t2STR_PRE killed $lr, $sp, -8, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: frame-setup CFI_INSTRUCTION def_cfa_offset 8
+    ;CHECK-NEXT: frame-setup CFI_INSTRUCTION offset $lr, -8
+    ;CHECK-NEXT: tBL 14 /* CC::al */, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    ;CHECK-NEXT: $r1 = t2LDREX $sp, 2, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $r1 = t2LDREX $sp, 10, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $r1 = t2LDREX $sp, 255, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $lr, $sp = t2LDR_POST $sp, 8, 14 /* CC::al */, $noreg
+
+    ;CHECK: name:           OUTLINED_FUNCTION_[[I8]]
+    ;CHECK: early-clobber $sp = t2STR_PRE killed $lr, $sp, -8, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: frame-setup CFI_INSTRUCTION def_cfa_offset 8
+    ;CHECK-NEXT: frame-setup CFI_INSTRUCTION offset $lr, -8
+    ;CHECK-NEXT: tBL 14 /* CC::al */, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    ;CHECK-NEXT: t2STRHi8 $r0, $sp, 8, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: t2STRHi8 $r0, $sp, 12, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: t2STRHi8 $r0, $sp, 255, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $lr, $sp = t2LDR_POST $sp, 8, 14 /* CC::al */, $noreg
+
+    ;CHECK: name:           OUTLINED_FUNCTION_[[I8S4]]
+    ;CHECK: early-clobber $sp = t2STR_PRE killed $lr, $sp, -8, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: frame-setup CFI_INSTRUCTION def_cfa_offset 8
+    ;CHECK-NEXT: frame-setup CFI_INSTRUCTION offset $lr, -8
+    ;CHECK-NEXT: tBL 14 /* CC::al */, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    ;CHECK-NEXT: t2STRDi8 $r0, $r1, $sp, 2, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: t2STRDi8 $r0, $r1, $sp, 10, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: t2STRDi8 $r0, $r1, $sp, 255, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $lr, $sp = t2LDR_POST $sp, 8, 14 /* CC::al */, $noreg
+
+    ;CHECK: name:           OUTLINED_FUNCTION_[[I12]]
+    ;CHECK: early-clobber $sp = t2STR_PRE killed $lr, $sp, -8, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: frame-setup CFI_INSTRUCTION def_cfa_offset 8
+    ;CHECK-NEXT: frame-setup CFI_INSTRUCTION offset $lr, -8
+    ;CHECK-NEXT: tBL 14 /* CC::al */, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    ;CHECK-NEXT: $r0 = t2LDRi12 $sp, 8, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $r0 = t2LDRi12 $sp, 12, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $r0 = t2LDRi12 $sp, 4094, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $lr, $sp = t2LDR_POST $sp, 8, 14 /* CC::al */, $noreg
+
+    ;CHECK: name:           OUTLINED_FUNCTION_[[T1_S]]
+    ;CHECK: early-clobber $sp = t2STR_PRE killed $lr, $sp, -8, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: frame-setup CFI_INSTRUCTION def_cfa_offset 8
+    ;CHECK-NEXT: frame-setup CFI_INSTRUCTION offset $lr, -8
+    ;CHECK-NEXT: tBL 14 /* CC::al */, $noreg, @foo, implicit-def dead $lr, implicit $sp
+    ;CHECK-NEXT: tSTRspi $r0, $sp, 2, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: tSTRspi $r0, $sp, 6, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: tSTRspi $r0, $sp, 255, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $lr, $sp = t2LDR_POST $sp, 8, 14 /* CC::al */, $noreg

llvm/test/tools/UpdateTestChecks/update_llc_test_checks/Inputs/arm_generated_funcs.ll

 ; RUN: llc -enable-machine-outliner -mtriple=arm-unknown-linux < %s | FileCheck %s
-;
-; NOTE: Machine outliner runs, but doesn't do anything.
 @x = global i32 0, align 4
 
 define i32 @check_boundaries() #0 {
   %1 = alloca i32, align 4
   %2 = alloca i32, align 4
   %3 = alloca i32, align 4
   %4 = alloca i32, align 4
   %5 = alloca i32, align 4

llvm/test/tools/UpdateTestChecks/update_llc_test_checks/Inputs/arm_generated_funcs.ll.generated.expected

 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --include-generated-funcs
 ; RUN: llc -enable-machine-outliner -mtriple=arm-unknown-linux < %s | FileCheck %s
-; NOTE: Machine outliner runs, but doesn't do anything.
 @x = global i32 0, align 4
 
 define i32 @check_boundaries() #0 {
   %1 = alloca i32, align 4
   %2 = alloca i32, align 4
   %3 = alloca i32, align 4
   %4 = alloca i32, align 4
   %5 = alloca i32, align 4

 ; CHECK-NEXT:    str r0, [sp, #12]
 ; CHECK-NEXT:    str r0, [sp, #16]
 ; CHECK-NEXT:    beq .LBB0_2
 ; CHECK-NEXT:  @ %bb.1:
 ; CHECK-NEXT:    mov r0, #1
 ; CHECK-NEXT:    str r0, [sp, #4]
 ; CHECK-NEXT:    b .LBB0_3
 ; CHECK-NEXT:  .LBB0_2:
-; CHECK-NEXT:    mov r0, #2
-; CHECK-NEXT:    str r0, [sp, #8]
-; CHECK-NEXT:    mov r0, #1
-; CHECK-NEXT:    str r0, [sp, #12]
-; CHECK-NEXT:    mov r0, #3
-; CHECK-NEXT:    str r0, [sp, #4]
-; CHECK-NEXT:    mov r0, #4
-; CHECK-NEXT:    str r0, [sp]
+; CHECK-NEXT:    mov r1, lr
+; CHECK-NEXT:    bl OUTLINED_FUNCTION_0
+; CHECK-NEXT:    mov lr, r1
 ; CHECK-NEXT:  .LBB0_3:
 ; CHECK-NEXT:    ldr r0, [sp, #12]
 ; CHECK-NEXT:    cmp r0, #0
 ; CHECK-NEXT:    beq .LBB0_5
 ; CHECK-NEXT:  @ %bb.4:
 ; CHECK-NEXT:    mov r0, #1
 ; CHECK-NEXT:    str r0, [sp, #4]
 ; CHECK-NEXT:    b .LBB0_6
 ; CHECK-NEXT:  .LBB0_5:
-; CHECK-NEXT:    mov r0, #2
-; CHECK-NEXT:    str r0, [sp, #8]
-; CHECK-NEXT:    mov r0, #1
-; CHECK-NEXT:    str r0, [sp, #12]
-; CHECK-NEXT:    mov r0, #3
-; CHECK-NEXT:    str r0, [sp, #4]
-; CHECK-NEXT:    mov r0, #4
-; CHECK-NEXT:    str r0, [sp]
+; CHECK-NEXT:    mov r1, lr
+; CHECK-NEXT:    bl OUTLINED_FUNCTION_0
+; CHECK-NEXT:    mov lr, r1
 ; CHECK-NEXT:  .LBB0_6:
 ; CHECK-NEXT:    mov r0, #0
 ; CHECK-NEXT:    add sp, sp, #20
 ; CHECK-NEXT:    mov pc, lr
 ;
 ; CHECK-LABEL: main:
 ; CHECK:       @ %bb.0:
 ; CHECK-NEXT:    sub sp, sp, #20

 ; CHECK-NEXT:    str r2, [sp, #4]
 ; CHECK-NEXT:    str r3, [sp]
 ; CHECK-NEXT:    add sp, sp, #20
 ; CHECK-NEXT:    mov pc, lr
 ; CHECK-NEXT:    .p2align 2
 ; CHECK-NEXT:  @ %bb.1:
 ; CHECK-NEXT:  .LCPI1_0:
 ; CHECK-NEXT:    .long x
+;
+; CHECK-LABEL: OUTLINED_FUNCTION_0:
+; CHECK:       @ %bb.0:
+; CHECK-NEXT:    mov r0, #2
+; CHECK-NEXT:    str r0, [sp, #8]
+; CHECK-NEXT:    mov r0, #1
+; CHECK-NEXT:    str r0, [sp, #12]
+; CHECK-NEXT:    mov r0, #3
+; CHECK-NEXT:    str r0, [sp, #4]
+; CHECK-NEXT:    mov r0, #4
+; CHECK-NEXT:    str r0, [sp]
+; CHECK-NEXT:    mov pc, lr

llvm/test/tools/UpdateTestChecks/update_llc_test_checks/Inputs/arm_generated_funcs.ll.nogenerated.expected

 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc -enable-machine-outliner -mtriple=arm-unknown-linux < %s | FileCheck %s
-;
-; NOTE: Machine outliner runs, but doesn't do anything.
 @x = global i32 0, align 4
 
 define i32 @check_boundaries() #0 {
 ; CHECK-LABEL: check_boundaries:
 ; CHECK:       @ %bb.0:
 ; CHECK-NEXT:    sub sp, sp, #20
 ; CHECK-NEXT:    mov r0, #0
 ; CHECK-NEXT:    cmp r0, #0
 ; CHECK-NEXT:    str r0, [sp, #12]
 ; CHECK-NEXT:    str r0, [sp, #16]
 ; CHECK-NEXT:    beq .LBB0_2
 ; CHECK-NEXT:  @ %bb.1:
 ; CHECK-NEXT:    mov r0, #1
 ; CHECK-NEXT:    str r0, [sp, #4]
 ; CHECK-NEXT:    b .LBB0_3
 ; CHECK-NEXT:  .LBB0_2:
-; CHECK-NEXT:    mov r0, #2
-; CHECK-NEXT:    str r0, [sp, #8]
-; CHECK-NEXT:    mov r0, #1
-; CHECK-NEXT:    str r0, [sp, #12]
-; CHECK-NEXT:    mov r0, #3
-; CHECK-NEXT:    str r0, [sp, #4]
-; CHECK-NEXT:    mov r0, #4
-; CHECK-NEXT:    str r0, [sp]
+; CHECK-NEXT:    mov r1, lr
+; CHECK-NEXT:    bl OUTLINED_FUNCTION_0
+; CHECK-NEXT:    mov lr, r1
 ; CHECK-NEXT:  .LBB0_3:
 ; CHECK-NEXT:    ldr r0, [sp, #12]
 ; CHECK-NEXT:    cmp r0, #0
 ; CHECK-NEXT:    beq .LBB0_5
 ; CHECK-NEXT:  @ %bb.4:
 ; CHECK-NEXT:    mov r0, #1
 ; CHECK-NEXT:    str r0, [sp, #4]
 ; CHECK-NEXT:    b .LBB0_6
 ; CHECK-NEXT:  .LBB0_5:
-; CHECK-NEXT:    mov r0, #2
-; CHECK-NEXT:    str r0, [sp, #8]
-; CHECK-NEXT:    mov r0, #1
-; CHECK-NEXT:    str r0, [sp, #12]
-; CHECK-NEXT:    mov r0, #3
-; CHECK-NEXT:    str r0, [sp, #4]
-; CHECK-NEXT:    mov r0, #4
-; CHECK-NEXT:    str r0, [sp]
+; CHECK-NEXT:    mov r1, lr
+; CHECK-NEXT:    bl OUTLINED_FUNCTION_0
+; CHECK-NEXT:    mov lr, r1
 ; CHECK-NEXT:  .LBB0_6:
 ; CHECK-NEXT:    mov r0, #0
 ; CHECK-NEXT:    add sp, sp, #20
 ; CHECK-NEXT:    mov pc, lr
   %1 = alloca i32, align 4
   %2 = alloca i32, align 4
   %3 = alloca i32, align 4
   %4 = alloca i32, align 4