llvm/llvm/lib/CodeGen/RenameIndependentSubregs.cpp

//===-- RenameIndependentSubregs.cpp - Live Interval Analysis -------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
/// Rename independent subregisters looks for virtual registers with
/// independently used subregisters and renames them to new virtual registers.
/// Example: In the following:
///   %0:sub0<read-undef> = ...
///   %0:sub1 = ...
///   use %0:sub0
///   %0:sub0 = ...
///   use %0:sub0
///   use %0:sub1
/// sub0 and sub1 are never used together, and we have two independent sub0
/// definitions. This pass will rename to:
///   %0:sub0<read-undef> = ...
///   %1:sub1<read-undef> = ...
///   use %1:sub1
///   %2:sub1<read-undef> = ...
///   use %2:sub1
///   use %0:sub0
//
//===----------------------------------------------------------------------===//

#include "LiveRangeUtils.h"
#include "PHIEliminationUtils.h"
#include "llvm/CodeGen/LiveInterval.h"
#include "llvm/CodeGen/LiveIntervals.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"

usingnamespacellvm;

#define DEBUG_TYPE …

namespace {

class RenameIndependentSubregs : public MachineFunctionPass { … };

} // end anonymous namespace

char RenameIndependentSubregs::ID;

char &llvm::RenameIndependentSubregsID = …;

INITIALIZE_PASS_BEGIN(RenameIndependentSubregs, DEBUG_TYPE,
                      "Rename Independent Subregisters", false, false)
INITIALIZE_PASS_DEPENDENCY(SlotIndexesWrapperPass)
INITIALIZE_PASS_DEPENDENCY(LiveIntervalsWrapperPass)
INITIALIZE_PASS_END(RenameIndependentSubregs, DEBUG_TYPE,
                    "Rename Independent Subregisters", false, false)

bool RenameIndependentSubregs::renameComponents(LiveInterval &LI) const { … }

bool RenameIndependentSubregs::findComponents(IntEqClasses &Classes,
    SmallVectorImpl<RenameIndependentSubregs::SubRangeInfo> &SubRangeInfos,
    LiveInterval &LI) const { … }

void RenameIndependentSubregs::rewriteOperands(const IntEqClasses &Classes,
    const SmallVectorImpl<SubRangeInfo> &SubRangeInfos,
    const SmallVectorImpl<LiveInterval*> &Intervals) const { … }

void RenameIndependentSubregs::distribute(const IntEqClasses &Classes,
    const SmallVectorImpl<SubRangeInfo> &SubRangeInfos,
    const SmallVectorImpl<LiveInterval*> &Intervals) const { … }

static bool subRangeLiveAt(const LiveInterval &LI, SlotIndex Pos) { … }

void RenameIndependentSubregs::computeMainRangesFixFlags(
    const IntEqClasses &Classes,
    const SmallVectorImpl<SubRangeInfo> &SubRangeInfos,
    const SmallVectorImpl<LiveInterval*> &Intervals) const { … }

bool RenameIndependentSubregs::runOnMachineFunction(MachineFunction &MF) { … }