llvm/llvm/lib/Target/ARM/MVEVPTBlockPass.cpp

//===-- MVEVPTBlockPass.cpp - Insert MVE VPT blocks -----------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "ARM.h"
#include "ARMMachineFunctionInfo.h"
#include "ARMSubtarget.h"
#include "MCTargetDesc/ARMBaseInfo.h"
#include "Thumb2InstrInfo.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineInstrBundle.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/MC/MCInstrDesc.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/Support/Debug.h"
#include <cassert>
#include <new>

usingnamespacellvm;

#define DEBUG_TYPE …

namespace {
class MVEVPTBlock : public MachineFunctionPass { … };

char MVEVPTBlock::ID = …;

} // end anonymous namespace

INITIALIZE_PASS(…)

static MachineInstr *findVCMPToFoldIntoVPST(MachineBasicBlock::iterator MI,
                                            const TargetRegisterInfo *TRI,
                                            unsigned &NewOpcode) { … }

// Advances Iter past a block of predicated instructions.
// Returns true if it successfully skipped the whole block of predicated
// instructions. Returns false when it stopped early (due to MaxSteps), or if
// Iter didn't point to a predicated instruction.
static bool StepOverPredicatedInstrs(MachineBasicBlock::instr_iterator &Iter,
                                     MachineBasicBlock::instr_iterator EndIter,
                                     unsigned MaxSteps,
                                     unsigned &NumInstrsSteppedOver) { … }

// Returns true if at least one instruction in the range [Iter, End) defines
// or kills VPR.
static bool IsVPRDefinedOrKilledByBlock(MachineBasicBlock::iterator Iter,
                                        MachineBasicBlock::iterator End) { … }

// Creates a T, TT, TTT or TTTT BlockMask depending on BlockSize.
static ARM::PredBlockMask GetInitialBlockMask(unsigned BlockSize) { … }

// Given an iterator (Iter) that points at an instruction with a "Then"
// predicate, tries to create the largest block of continuous predicated
// instructions possible, and returns the VPT Block Mask of that block.
//
// This will try to perform some minor optimization in order to maximize the
// size of the block.
static ARM::PredBlockMask
CreateVPTBlock(MachineBasicBlock::instr_iterator &Iter,
               MachineBasicBlock::instr_iterator EndIter,
               SmallVectorImpl<MachineInstr *> &DeadInstructions) { … }

bool MVEVPTBlock::InsertVPTBlocks(MachineBasicBlock &Block) { … }

bool MVEVPTBlock::runOnMachineFunction(MachineFunction &Fn) { … }

/// createMVEVPTBlock - Returns an instance of the MVE VPT block
/// insertion pass.
FunctionPass *llvm::createMVEVPTBlockPass() { … }