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      1 //===- llvm/CodeGen/GlobalISel/InstructionSelector.cpp --------------------===//
      2 //
      3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
      4 // See https://llvm.org/LICENSE.txt for license information.
      5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
      6 //
      7 //===----------------------------------------------------------------------===//
      8 //
      9 /// \file
     10 /// This file implements the InstructionSelector class.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "llvm/CodeGen/GlobalISel/InstructionSelector.h"
     15 #include "llvm/CodeGen/GlobalISel/Utils.h"
     16 #include "llvm/CodeGen/MachineBasicBlock.h"
     17 #include "llvm/CodeGen/MachineFunction.h"
     18 #include "llvm/CodeGen/MachineInstr.h"
     19 #include "llvm/CodeGen/MachineOperand.h"
     20 #include "llvm/CodeGen/MachineRegisterInfo.h"
     21 #include "llvm/CodeGen/TargetRegisterInfo.h"
     22 #include "llvm/MC/MCInstrDesc.h"
     23 #include "llvm/Support/Debug.h"
     24 #include "llvm/Support/raw_ostream.h"
     25 #include <cassert>
     26 
     27 #define DEBUG_TYPE "instructionselector"
     28 
     29 using namespace llvm;
     30 
     31 InstructionSelector::MatcherState::MatcherState(unsigned MaxRenderers)
     32     : Renderers(MaxRenderers), MIs() {}
     33 
     34 InstructionSelector::InstructionSelector() = default;
     35 
     36 bool InstructionSelector::isOperandImmEqual(
     37     const MachineOperand &MO, int64_t Value,
     38     const MachineRegisterInfo &MRI) const {
     39   if (MO.isReg() && MO.getReg())
     40     if (auto VRegVal = getConstantVRegValWithLookThrough(MO.getReg(), MRI))
     41       return VRegVal->Value.getSExtValue() == Value;
     42   return false;
     43 }
     44 
     45 bool InstructionSelector::isBaseWithConstantOffset(
     46     const MachineOperand &Root, const MachineRegisterInfo &MRI) const {
     47   if (!Root.isReg())
     48     return false;
     49 
     50   MachineInstr *RootI = MRI.getVRegDef(Root.getReg());
     51   if (RootI->getOpcode() != TargetOpcode::G_PTR_ADD)
     52     return false;
     53 
     54   MachineOperand &RHS = RootI->getOperand(2);
     55   MachineInstr *RHSI = MRI.getVRegDef(RHS.getReg());
     56   if (RHSI->getOpcode() != TargetOpcode::G_CONSTANT)
     57     return false;
     58 
     59   return true;
     60 }
     61 
     62 bool InstructionSelector::isObviouslySafeToFold(MachineInstr &MI,
     63                                                 MachineInstr &IntoMI) const {
     64   // Immediate neighbours are already folded.
     65   if (MI.getParent() == IntoMI.getParent() &&
     66       std::next(MI.getIterator()) == IntoMI.getIterator())
     67     return true;
     68 
     69   return !MI.mayLoadOrStore() && !MI.mayRaiseFPException() &&
     70          !MI.hasUnmodeledSideEffects() && MI.implicit_operands().empty();
     71 }
     72