Revert "[ARM][Thumb2] Mark BTI-clearing instructions as scheduling region boundaries" (#87699)

Reverts #79173

The testcase fails in non-asserts builds.

Author: vhscampos

llvm/lib/Target/ARM/Thumb2InstrInfo.cpp

@@ -286,25 +286,6 @@ MachineInstr *Thumb2InstrInfo::commuteInstructionImpl(MachineInstr &MI,
   return ARMBaseInstrInfo::commuteInstructionImpl(MI, NewMI, OpIdx1, OpIdx2);
 }
 
-bool Thumb2InstrInfo::isSchedulingBoundary(const MachineInstr &MI,
-                                           const MachineBasicBlock *MBB,
-                                           const MachineFunction &MF) const {
-  // BTI clearing instructions shall not take part in scheduling regions as
-  // they must stay in their intended place. Although PAC isn't BTI clearing,
-  // it can be transformed into PACBTI after the pre-RA Machine Scheduling
-  // has taken place, so its movement must also be restricted.
-  switch (MI.getOpcode()) {
-  case ARM::t2BTI:
-  case ARM::t2PAC:
-  case ARM::t2PACBTI:
-  case ARM::t2SG:
-    return true;
-  default:
-    break;
-  }
-  return ARMBaseInstrInfo::isSchedulingBoundary(MI, MBB, MF);
-}
-
 void llvm::emitT2RegPlusImmediate(MachineBasicBlock &MBB,
                                   MachineBasicBlock::iterator &MBBI,
                                   const DebugLoc &dl, Register DestReg,

llvm/lib/Target/ARM/Thumb2InstrInfo.h

@@ -68,10 +68,6 @@ class Thumb2InstrInfo : public ARMBaseInstrInfo {
                                        unsigned OpIdx1,
                                        unsigned OpIdx2) const override;
 
-  bool isSchedulingBoundary(const MachineInstr &MI,
-                            const MachineBasicBlock *MBB,
-                            const MachineFunction &MF) const override;
-
 private:
   void expandLoadStackGuard(MachineBasicBlock::iterator MI) const override;
 };