llvm/lib/CodeGen/GlobalISel/InstructionSelector.cpp

   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 }