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https://github.com/c64scene-ar/llvm-6502.git
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5b69ebac85
This fixes a very subtle bug. vr defined by an implicit_def is allowed overlap with any register since it doesn't actually modify anything. However, if it's used as a two-address use, its live range can be extended and it can be spilled. The spiller must take care not to emit a reload for the vn number that's defined by the implicit_def. This is both a correctness and performance issue. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@69743 91177308-0d34-0410-b5e6-96231b3b80d8
1897 lines
74 KiB
C++
1897 lines
74 KiB
C++
//===-- llvm/CodeGen/Spiller.cpp - Spiller -------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "spiller"
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#include "Spiller.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/ADT/DepthFirstIterator.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/ADT/STLExtras.h"
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#include <algorithm>
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using namespace llvm;
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STATISTIC(NumDSE , "Number of dead stores elided");
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STATISTIC(NumDSS , "Number of dead spill slots removed");
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STATISTIC(NumCommutes, "Number of instructions commuted");
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STATISTIC(NumDRM , "Number of re-materializable defs elided");
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STATISTIC(NumStores , "Number of stores added");
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STATISTIC(NumPSpills , "Number of physical register spills");
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STATISTIC(NumOmitted , "Number of reloads omited");
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STATISTIC(NumAvoided , "Number of reloads deemed unnecessary");
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STATISTIC(NumCopified, "Number of available reloads turned into copies");
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STATISTIC(NumReMats , "Number of re-materialization");
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STATISTIC(NumLoads , "Number of loads added");
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STATISTIC(NumReused , "Number of values reused");
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STATISTIC(NumDCE , "Number of copies elided");
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STATISTIC(NumSUnfold , "Number of stores unfolded");
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STATISTIC(NumModRefUnfold, "Number of modref unfolded");
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namespace {
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enum SpillerName { simple, local };
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}
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static cl::opt<SpillerName>
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SpillerOpt("spiller",
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cl::desc("Spiller to use: (default: local)"),
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cl::Prefix,
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cl::values(clEnumVal(simple, "simple spiller"),
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clEnumVal(local, "local spiller"),
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clEnumValEnd),
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cl::init(local));
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// ****************************** //
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// Simple Spiller Implementation //
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// ****************************** //
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Spiller::~Spiller() {}
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bool SimpleSpiller::runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM,
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LiveIntervals* LIs) {
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DOUT << "********** REWRITE MACHINE CODE **********\n";
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DOUT << "********** Function: " << MF.getFunction()->getName() << '\n';
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const TargetMachine &TM = MF.getTarget();
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const TargetInstrInfo &TII = *TM.getInstrInfo();
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const TargetRegisterInfo &TRI = *TM.getRegisterInfo();
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// LoadedRegs - Keep track of which vregs are loaded, so that we only load
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// each vreg once (in the case where a spilled vreg is used by multiple
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// operands). This is always smaller than the number of operands to the
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// current machine instr, so it should be small.
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std::vector<unsigned> LoadedRegs;
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for (MachineFunction::iterator MBBI = MF.begin(), E = MF.end();
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MBBI != E; ++MBBI) {
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DOUT << MBBI->getBasicBlock()->getName() << ":\n";
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MachineBasicBlock &MBB = *MBBI;
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for (MachineBasicBlock::iterator MII = MBB.begin(), E = MBB.end();
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MII != E; ++MII) {
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MachineInstr &MI = *MII;
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for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
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MachineOperand &MO = MI.getOperand(i);
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if (MO.isReg() && MO.getReg()) {
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if (TargetRegisterInfo::isVirtualRegister(MO.getReg())) {
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unsigned VirtReg = MO.getReg();
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unsigned SubIdx = MO.getSubReg();
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unsigned PhysReg = VRM.getPhys(VirtReg);
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unsigned RReg = SubIdx ? TRI.getSubReg(PhysReg, SubIdx) : PhysReg;
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if (!VRM.isAssignedReg(VirtReg)) {
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int StackSlot = VRM.getStackSlot(VirtReg);
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const TargetRegisterClass* RC =
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MF.getRegInfo().getRegClass(VirtReg);
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if (MO.isUse() &&
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std::find(LoadedRegs.begin(), LoadedRegs.end(), VirtReg)
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== LoadedRegs.end()) {
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TII.loadRegFromStackSlot(MBB, &MI, PhysReg, StackSlot, RC);
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MachineInstr *LoadMI = prior(MII);
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VRM.addSpillSlotUse(StackSlot, LoadMI);
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LoadedRegs.push_back(VirtReg);
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++NumLoads;
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DOUT << '\t' << *LoadMI;
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}
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if (MO.isDef()) {
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TII.storeRegToStackSlot(MBB, next(MII), PhysReg, true,
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StackSlot, RC);
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MachineInstr *StoreMI = next(MII);
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VRM.addSpillSlotUse(StackSlot, StoreMI);
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++NumStores;
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}
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}
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MF.getRegInfo().setPhysRegUsed(RReg);
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MI.getOperand(i).setReg(RReg);
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MI.getOperand(i).setSubReg(0);
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} else {
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MF.getRegInfo().setPhysRegUsed(MO.getReg());
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}
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}
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}
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DOUT << '\t' << MI;
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LoadedRegs.clear();
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}
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}
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return true;
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}
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// ****************** //
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// Utility Functions //
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// ****************** //
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/// InvalidateKill - A MI that defines the specified register is being deleted,
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/// invalidate the register kill information.
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static void InvalidateKill(unsigned Reg, BitVector &RegKills,
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std::vector<MachineOperand*> &KillOps) {
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if (RegKills[Reg]) {
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KillOps[Reg]->setIsKill(false);
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KillOps[Reg] = NULL;
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RegKills.reset(Reg);
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}
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}
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/// findSinglePredSuccessor - Return via reference a vector of machine basic
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/// blocks each of which is a successor of the specified BB and has no other
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/// predecessor.
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static void findSinglePredSuccessor(MachineBasicBlock *MBB,
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SmallVectorImpl<MachineBasicBlock *> &Succs) {
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for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
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SE = MBB->succ_end(); SI != SE; ++SI) {
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MachineBasicBlock *SuccMBB = *SI;
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if (SuccMBB->pred_size() == 1)
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Succs.push_back(SuccMBB);
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}
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}
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/// InvalidateKills - MI is going to be deleted. If any of its operands are
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/// marked kill, then invalidate the information.
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static void InvalidateKills(MachineInstr &MI, BitVector &RegKills,
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std::vector<MachineOperand*> &KillOps,
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SmallVector<unsigned, 2> *KillRegs = NULL) {
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for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
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MachineOperand &MO = MI.getOperand(i);
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if (!MO.isReg() || !MO.isUse() || !MO.isKill())
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continue;
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unsigned Reg = MO.getReg();
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if (TargetRegisterInfo::isVirtualRegister(Reg))
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continue;
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if (KillRegs)
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KillRegs->push_back(Reg);
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assert(Reg < KillOps.size());
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if (KillOps[Reg] == &MO) {
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RegKills.reset(Reg);
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KillOps[Reg] = NULL;
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}
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}
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}
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/// InvalidateRegDef - If the def operand of the specified def MI is now dead
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/// (since it's spill instruction is removed), mark it isDead. Also checks if
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/// the def MI has other definition operands that are not dead. Returns it by
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/// reference.
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static bool InvalidateRegDef(MachineBasicBlock::iterator I,
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MachineInstr &NewDef, unsigned Reg,
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bool &HasLiveDef) {
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// Due to remat, it's possible this reg isn't being reused. That is,
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// the def of this reg (by prev MI) is now dead.
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MachineInstr *DefMI = I;
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MachineOperand *DefOp = NULL;
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for (unsigned i = 0, e = DefMI->getNumOperands(); i != e; ++i) {
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MachineOperand &MO = DefMI->getOperand(i);
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if (MO.isReg() && MO.isDef()) {
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if (MO.getReg() == Reg)
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DefOp = &MO;
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else if (!MO.isDead())
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HasLiveDef = true;
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}
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}
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if (!DefOp)
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return false;
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bool FoundUse = false, Done = false;
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MachineBasicBlock::iterator E = &NewDef;
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++I; ++E;
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for (; !Done && I != E; ++I) {
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MachineInstr *NMI = I;
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for (unsigned j = 0, ee = NMI->getNumOperands(); j != ee; ++j) {
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MachineOperand &MO = NMI->getOperand(j);
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if (!MO.isReg() || MO.getReg() != Reg)
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continue;
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if (MO.isUse())
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FoundUse = true;
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Done = true; // Stop after scanning all the operands of this MI.
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}
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}
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if (!FoundUse) {
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// Def is dead!
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DefOp->setIsDead();
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return true;
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}
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return false;
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}
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/// UpdateKills - Track and update kill info. If a MI reads a register that is
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/// marked kill, then it must be due to register reuse. Transfer the kill info
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/// over.
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static void UpdateKills(MachineInstr &MI, BitVector &RegKills,
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std::vector<MachineOperand*> &KillOps,
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const TargetRegisterInfo* TRI) {
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for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
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MachineOperand &MO = MI.getOperand(i);
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if (!MO.isReg() || !MO.isUse())
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continue;
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unsigned Reg = MO.getReg();
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if (Reg == 0)
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continue;
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if (RegKills[Reg] && KillOps[Reg]->getParent() != &MI) {
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// That can't be right. Register is killed but not re-defined and it's
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// being reused. Let's fix that.
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KillOps[Reg]->setIsKill(false);
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KillOps[Reg] = NULL;
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RegKills.reset(Reg);
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if (!MI.isRegTiedToDefOperand(i))
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// Unless it's a two-address operand, this is the new kill.
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MO.setIsKill();
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}
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if (MO.isKill()) {
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RegKills.set(Reg);
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KillOps[Reg] = &MO;
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}
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}
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for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
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const MachineOperand &MO = MI.getOperand(i);
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if (!MO.isReg() || !MO.isDef())
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continue;
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unsigned Reg = MO.getReg();
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RegKills.reset(Reg);
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KillOps[Reg] = NULL;
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// It also defines (or partially define) aliases.
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for (const unsigned *AS = TRI->getAliasSet(Reg); *AS; ++AS) {
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RegKills.reset(*AS);
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KillOps[*AS] = NULL;
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}
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}
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}
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/// ReMaterialize - Re-materialize definition for Reg targetting DestReg.
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///
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static void ReMaterialize(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator &MII,
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unsigned DestReg, unsigned Reg,
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const TargetInstrInfo *TII,
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const TargetRegisterInfo *TRI,
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VirtRegMap &VRM) {
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TII->reMaterialize(MBB, MII, DestReg, VRM.getReMaterializedMI(Reg));
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MachineInstr *NewMI = prior(MII);
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for (unsigned i = 0, e = NewMI->getNumOperands(); i != e; ++i) {
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MachineOperand &MO = NewMI->getOperand(i);
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if (!MO.isReg() || MO.getReg() == 0)
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continue;
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unsigned VirtReg = MO.getReg();
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if (TargetRegisterInfo::isPhysicalRegister(VirtReg))
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continue;
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assert(MO.isUse());
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unsigned SubIdx = MO.getSubReg();
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unsigned Phys = VRM.getPhys(VirtReg);
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assert(Phys);
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unsigned RReg = SubIdx ? TRI->getSubReg(Phys, SubIdx) : Phys;
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MO.setReg(RReg);
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MO.setSubReg(0);
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}
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++NumReMats;
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}
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/// findSuperReg - Find the SubReg's super-register of given register class
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/// where its SubIdx sub-register is SubReg.
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static unsigned findSuperReg(const TargetRegisterClass *RC, unsigned SubReg,
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unsigned SubIdx, const TargetRegisterInfo *TRI) {
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for (TargetRegisterClass::iterator I = RC->begin(), E = RC->end();
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I != E; ++I) {
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unsigned Reg = *I;
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if (TRI->getSubReg(Reg, SubIdx) == SubReg)
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return Reg;
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}
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return 0;
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}
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// ******************************** //
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// Available Spills Implementation //
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// ******************************** //
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/// disallowClobberPhysRegOnly - Unset the CanClobber bit of the specified
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/// stackslot register. The register is still available but is no longer
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/// allowed to be modifed.
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void AvailableSpills::disallowClobberPhysRegOnly(unsigned PhysReg) {
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std::multimap<unsigned, int>::iterator I =
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PhysRegsAvailable.lower_bound(PhysReg);
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while (I != PhysRegsAvailable.end() && I->first == PhysReg) {
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int SlotOrReMat = I->second;
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I++;
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assert((SpillSlotsOrReMatsAvailable[SlotOrReMat] >> 1) == PhysReg &&
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"Bidirectional map mismatch!");
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SpillSlotsOrReMatsAvailable[SlotOrReMat] &= ~1;
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DOUT << "PhysReg " << TRI->getName(PhysReg)
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<< " copied, it is available for use but can no longer be modified\n";
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}
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}
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/// disallowClobberPhysReg - Unset the CanClobber bit of the specified
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/// stackslot register and its aliases. The register and its aliases may
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/// still available but is no longer allowed to be modifed.
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void AvailableSpills::disallowClobberPhysReg(unsigned PhysReg) {
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for (const unsigned *AS = TRI->getAliasSet(PhysReg); *AS; ++AS)
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disallowClobberPhysRegOnly(*AS);
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disallowClobberPhysRegOnly(PhysReg);
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}
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/// ClobberPhysRegOnly - This is called when the specified physreg changes
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/// value. We use this to invalidate any info about stuff we thing lives in it.
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void AvailableSpills::ClobberPhysRegOnly(unsigned PhysReg) {
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std::multimap<unsigned, int>::iterator I =
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PhysRegsAvailable.lower_bound(PhysReg);
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while (I != PhysRegsAvailable.end() && I->first == PhysReg) {
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int SlotOrReMat = I->second;
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PhysRegsAvailable.erase(I++);
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assert((SpillSlotsOrReMatsAvailable[SlotOrReMat] >> 1) == PhysReg &&
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"Bidirectional map mismatch!");
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SpillSlotsOrReMatsAvailable.erase(SlotOrReMat);
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DOUT << "PhysReg " << TRI->getName(PhysReg)
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<< " clobbered, invalidating ";
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if (SlotOrReMat > VirtRegMap::MAX_STACK_SLOT)
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DOUT << "RM#" << SlotOrReMat-VirtRegMap::MAX_STACK_SLOT-1 << "\n";
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else
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DOUT << "SS#" << SlotOrReMat << "\n";
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}
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}
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/// ClobberPhysReg - This is called when the specified physreg changes
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/// value. We use this to invalidate any info about stuff we thing lives in
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/// it and any of its aliases.
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void AvailableSpills::ClobberPhysReg(unsigned PhysReg) {
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for (const unsigned *AS = TRI->getAliasSet(PhysReg); *AS; ++AS)
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ClobberPhysRegOnly(*AS);
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ClobberPhysRegOnly(PhysReg);
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}
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/// AddAvailableRegsToLiveIn - Availability information is being kept coming
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/// into the specified MBB. Add available physical registers as potential
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/// live-in's. If they are reused in the MBB, they will be added to the
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/// live-in set to make register scavenger and post-allocation scheduler.
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void AvailableSpills::AddAvailableRegsToLiveIn(MachineBasicBlock &MBB,
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BitVector &RegKills,
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std::vector<MachineOperand*> &KillOps) {
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std::set<unsigned> NotAvailable;
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for (std::multimap<unsigned, int>::iterator
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I = PhysRegsAvailable.begin(), E = PhysRegsAvailable.end();
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I != E; ++I) {
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unsigned Reg = I->first;
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const TargetRegisterClass* RC = TRI->getPhysicalRegisterRegClass(Reg);
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// FIXME: A temporary workaround. We can't reuse available value if it's
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// not safe to move the def of the virtual register's class. e.g.
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// X86::RFP* register classes. Do not add it as a live-in.
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if (!TII->isSafeToMoveRegClassDefs(RC))
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// This is no longer available.
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NotAvailable.insert(Reg);
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else {
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MBB.addLiveIn(Reg);
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InvalidateKill(Reg, RegKills, KillOps);
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}
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// Skip over the same register.
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std::multimap<unsigned, int>::iterator NI = next(I);
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while (NI != E && NI->first == Reg) {
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++I;
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++NI;
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}
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}
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for (std::set<unsigned>::iterator I = NotAvailable.begin(),
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E = NotAvailable.end(); I != E; ++I) {
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ClobberPhysReg(*I);
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for (const unsigned *SubRegs = TRI->getSubRegisters(*I);
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*SubRegs; ++SubRegs)
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ClobberPhysReg(*SubRegs);
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}
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}
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/// ModifyStackSlotOrReMat - This method is called when the value in a stack
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/// slot changes. This removes information about which register the previous
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/// value for this slot lives in (as the previous value is dead now).
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void AvailableSpills::ModifyStackSlotOrReMat(int SlotOrReMat) {
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std::map<int, unsigned>::iterator It =
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SpillSlotsOrReMatsAvailable.find(SlotOrReMat);
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if (It == SpillSlotsOrReMatsAvailable.end()) return;
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unsigned Reg = It->second >> 1;
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SpillSlotsOrReMatsAvailable.erase(It);
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// This register may hold the value of multiple stack slots, only remove this
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// stack slot from the set of values the register contains.
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std::multimap<unsigned, int>::iterator I = PhysRegsAvailable.lower_bound(Reg);
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for (; ; ++I) {
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assert(I != PhysRegsAvailable.end() && I->first == Reg &&
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"Map inverse broken!");
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if (I->second == SlotOrReMat) break;
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}
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PhysRegsAvailable.erase(I);
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}
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// ************************** //
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// Reuse Info Implementation //
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// ************************** //
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/// GetRegForReload - We are about to emit a reload into PhysReg. If there
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/// is some other operand that is using the specified register, either pick
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/// a new register to use, or evict the previous reload and use this reg.
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unsigned ReuseInfo::GetRegForReload(unsigned PhysReg, MachineInstr *MI,
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AvailableSpills &Spills,
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std::vector<MachineInstr*> &MaybeDeadStores,
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SmallSet<unsigned, 8> &Rejected,
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BitVector &RegKills,
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std::vector<MachineOperand*> &KillOps,
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VirtRegMap &VRM) {
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const TargetInstrInfo* TII = MI->getParent()->getParent()->getTarget()
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.getInstrInfo();
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if (Reuses.empty()) return PhysReg; // This is most often empty.
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for (unsigned ro = 0, e = Reuses.size(); ro != e; ++ro) {
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ReusedOp &Op = Reuses[ro];
|
|
// If we find some other reuse that was supposed to use this register
|
|
// exactly for its reload, we can change this reload to use ITS reload
|
|
// register. That is, unless its reload register has already been
|
|
// considered and subsequently rejected because it has also been reused
|
|
// by another operand.
|
|
if (Op.PhysRegReused == PhysReg &&
|
|
Rejected.count(Op.AssignedPhysReg) == 0) {
|
|
// Yup, use the reload register that we didn't use before.
|
|
unsigned NewReg = Op.AssignedPhysReg;
|
|
Rejected.insert(PhysReg);
|
|
return GetRegForReload(NewReg, MI, Spills, MaybeDeadStores, Rejected,
|
|
RegKills, KillOps, VRM);
|
|
} else {
|
|
// Otherwise, we might also have a problem if a previously reused
|
|
// value aliases the new register. If so, codegen the previous reload
|
|
// and use this one.
|
|
unsigned PRRU = Op.PhysRegReused;
|
|
const TargetRegisterInfo *TRI = Spills.getRegInfo();
|
|
if (TRI->areAliases(PRRU, PhysReg)) {
|
|
// Okay, we found out that an alias of a reused register
|
|
// was used. This isn't good because it means we have
|
|
// to undo a previous reuse.
|
|
MachineBasicBlock *MBB = MI->getParent();
|
|
const TargetRegisterClass *AliasRC =
|
|
MBB->getParent()->getRegInfo().getRegClass(Op.VirtReg);
|
|
|
|
// Copy Op out of the vector and remove it, we're going to insert an
|
|
// explicit load for it.
|
|
ReusedOp NewOp = Op;
|
|
Reuses.erase(Reuses.begin()+ro);
|
|
|
|
// Ok, we're going to try to reload the assigned physreg into the
|
|
// slot that we were supposed to in the first place. However, that
|
|
// register could hold a reuse. Check to see if it conflicts or
|
|
// would prefer us to use a different register.
|
|
unsigned NewPhysReg = GetRegForReload(NewOp.AssignedPhysReg,
|
|
MI, Spills, MaybeDeadStores,
|
|
Rejected, RegKills, KillOps, VRM);
|
|
|
|
MachineBasicBlock::iterator MII = MI;
|
|
if (NewOp.StackSlotOrReMat > VirtRegMap::MAX_STACK_SLOT) {
|
|
ReMaterialize(*MBB, MII, NewPhysReg, NewOp.VirtReg, TII, TRI,VRM);
|
|
} else {
|
|
TII->loadRegFromStackSlot(*MBB, MII, NewPhysReg,
|
|
NewOp.StackSlotOrReMat, AliasRC);
|
|
MachineInstr *LoadMI = prior(MII);
|
|
VRM.addSpillSlotUse(NewOp.StackSlotOrReMat, LoadMI);
|
|
// Any stores to this stack slot are not dead anymore.
|
|
MaybeDeadStores[NewOp.StackSlotOrReMat] = NULL;
|
|
++NumLoads;
|
|
}
|
|
Spills.ClobberPhysReg(NewPhysReg);
|
|
Spills.ClobberPhysReg(NewOp.PhysRegReused);
|
|
|
|
unsigned SubIdx = MI->getOperand(NewOp.Operand).getSubReg();
|
|
unsigned RReg = SubIdx ? TRI->getSubReg(NewPhysReg, SubIdx) : NewPhysReg;
|
|
MI->getOperand(NewOp.Operand).setReg(RReg);
|
|
MI->getOperand(NewOp.Operand).setSubReg(0);
|
|
|
|
Spills.addAvailable(NewOp.StackSlotOrReMat, NewPhysReg);
|
|
--MII;
|
|
UpdateKills(*MII, RegKills, KillOps, TRI);
|
|
DOUT << '\t' << *MII;
|
|
|
|
DOUT << "Reuse undone!\n";
|
|
--NumReused;
|
|
|
|
// Finally, PhysReg is now available, go ahead and use it.
|
|
return PhysReg;
|
|
}
|
|
}
|
|
}
|
|
return PhysReg;
|
|
}
|
|
|
|
// ***************************** //
|
|
// Local Spiller Implementation //
|
|
// ***************************** //
|
|
|
|
bool LocalSpiller::runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM,
|
|
LiveIntervals* LIs) {
|
|
RegInfo = &MF.getRegInfo();
|
|
TRI = MF.getTarget().getRegisterInfo();
|
|
TII = MF.getTarget().getInstrInfo();
|
|
AllocatableRegs = TRI->getAllocatableSet(MF);
|
|
DOUT << "\n**** Local spiller rewriting function '"
|
|
<< MF.getFunction()->getName() << "':\n";
|
|
DOUT << "**** Machine Instrs (NOTE! Does not include spills and reloads!)"
|
|
" ****\n";
|
|
DEBUG(MF.dump());
|
|
|
|
// Spills - Keep track of which spilled values are available in physregs
|
|
// so that we can choose to reuse the physregs instead of emitting
|
|
// reloads. This is usually refreshed per basic block.
|
|
AvailableSpills Spills(TRI, TII);
|
|
|
|
// Keep track of kill information.
|
|
BitVector RegKills(TRI->getNumRegs());
|
|
std::vector<MachineOperand*> KillOps;
|
|
KillOps.resize(TRI->getNumRegs(), NULL);
|
|
|
|
// SingleEntrySuccs - Successor blocks which have a single predecessor.
|
|
SmallVector<MachineBasicBlock*, 4> SinglePredSuccs;
|
|
SmallPtrSet<MachineBasicBlock*,16> EarlyVisited;
|
|
|
|
// Traverse the basic blocks depth first.
|
|
MachineBasicBlock *Entry = MF.begin();
|
|
SmallPtrSet<MachineBasicBlock*,16> Visited;
|
|
for (df_ext_iterator<MachineBasicBlock*,
|
|
SmallPtrSet<MachineBasicBlock*,16> >
|
|
DFI = df_ext_begin(Entry, Visited), E = df_ext_end(Entry, Visited);
|
|
DFI != E; ++DFI) {
|
|
MachineBasicBlock *MBB = *DFI;
|
|
if (!EarlyVisited.count(MBB))
|
|
RewriteMBB(*MBB, VRM, LIs, Spills, RegKills, KillOps);
|
|
|
|
// If this MBB is the only predecessor of a successor. Keep the
|
|
// availability information and visit it next.
|
|
do {
|
|
// Keep visiting single predecessor successor as long as possible.
|
|
SinglePredSuccs.clear();
|
|
findSinglePredSuccessor(MBB, SinglePredSuccs);
|
|
if (SinglePredSuccs.empty())
|
|
MBB = 0;
|
|
else {
|
|
// FIXME: More than one successors, each of which has MBB has
|
|
// the only predecessor.
|
|
MBB = SinglePredSuccs[0];
|
|
if (!Visited.count(MBB) && EarlyVisited.insert(MBB)) {
|
|
Spills.AddAvailableRegsToLiveIn(*MBB, RegKills, KillOps);
|
|
RewriteMBB(*MBB, VRM, LIs, Spills, RegKills, KillOps);
|
|
}
|
|
}
|
|
} while (MBB);
|
|
|
|
// Clear the availability info.
|
|
Spills.clear();
|
|
}
|
|
|
|
DOUT << "**** Post Machine Instrs ****\n";
|
|
DEBUG(MF.dump());
|
|
|
|
// Mark unused spill slots.
|
|
MachineFrameInfo *MFI = MF.getFrameInfo();
|
|
int SS = VRM.getLowSpillSlot();
|
|
if (SS != VirtRegMap::NO_STACK_SLOT)
|
|
for (int e = VRM.getHighSpillSlot(); SS <= e; ++SS)
|
|
if (!VRM.isSpillSlotUsed(SS)) {
|
|
MFI->RemoveStackObject(SS);
|
|
++NumDSS;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
|
|
/// FoldsStackSlotModRef - Return true if the specified MI folds the specified
|
|
/// stack slot mod/ref. It also checks if it's possible to unfold the
|
|
/// instruction by having it define a specified physical register instead.
|
|
static bool FoldsStackSlotModRef(MachineInstr &MI, int SS, unsigned PhysReg,
|
|
const TargetInstrInfo *TII,
|
|
const TargetRegisterInfo *TRI,
|
|
VirtRegMap &VRM) {
|
|
if (VRM.hasEmergencySpills(&MI) || VRM.isSpillPt(&MI))
|
|
return false;
|
|
|
|
bool Found = false;
|
|
VirtRegMap::MI2VirtMapTy::const_iterator I, End;
|
|
for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ++I) {
|
|
unsigned VirtReg = I->second.first;
|
|
VirtRegMap::ModRef MR = I->second.second;
|
|
if (MR & VirtRegMap::isModRef)
|
|
if (VRM.getStackSlot(VirtReg) == SS) {
|
|
Found= TII->getOpcodeAfterMemoryUnfold(MI.getOpcode(), true, true) != 0;
|
|
break;
|
|
}
|
|
}
|
|
if (!Found)
|
|
return false;
|
|
|
|
// Does the instruction uses a register that overlaps the scratch register?
|
|
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI.getOperand(i);
|
|
if (!MO.isReg() || MO.getReg() == 0)
|
|
continue;
|
|
unsigned Reg = MO.getReg();
|
|
if (TargetRegisterInfo::isVirtualRegister(Reg)) {
|
|
if (!VRM.hasPhys(Reg))
|
|
continue;
|
|
Reg = VRM.getPhys(Reg);
|
|
}
|
|
if (TRI->regsOverlap(PhysReg, Reg))
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// FindFreeRegister - Find a free register of a given register class by looking
|
|
/// at (at most) the last two machine instructions.
|
|
static unsigned FindFreeRegister(MachineBasicBlock::iterator MII,
|
|
MachineBasicBlock &MBB,
|
|
const TargetRegisterClass *RC,
|
|
const TargetRegisterInfo *TRI,
|
|
BitVector &AllocatableRegs) {
|
|
BitVector Defs(TRI->getNumRegs());
|
|
BitVector Uses(TRI->getNumRegs());
|
|
SmallVector<unsigned, 4> LocalUses;
|
|
SmallVector<unsigned, 4> Kills;
|
|
|
|
// Take a look at 2 instructions at most.
|
|
for (unsigned Count = 0; Count < 2; ++Count) {
|
|
if (MII == MBB.begin())
|
|
break;
|
|
MachineInstr *PrevMI = prior(MII);
|
|
for (unsigned i = 0, e = PrevMI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = PrevMI->getOperand(i);
|
|
if (!MO.isReg() || MO.getReg() == 0)
|
|
continue;
|
|
unsigned Reg = MO.getReg();
|
|
if (MO.isDef()) {
|
|
Defs.set(Reg);
|
|
for (const unsigned *AS = TRI->getAliasSet(Reg); *AS; ++AS)
|
|
Defs.set(*AS);
|
|
} else {
|
|
LocalUses.push_back(Reg);
|
|
if (MO.isKill() && AllocatableRegs[Reg])
|
|
Kills.push_back(Reg);
|
|
}
|
|
}
|
|
|
|
for (unsigned i = 0, e = Kills.size(); i != e; ++i) {
|
|
unsigned Kill = Kills[i];
|
|
if (!Defs[Kill] && !Uses[Kill] &&
|
|
TRI->getPhysicalRegisterRegClass(Kill) == RC)
|
|
return Kill;
|
|
}
|
|
for (unsigned i = 0, e = LocalUses.size(); i != e; ++i) {
|
|
unsigned Reg = LocalUses[i];
|
|
Uses.set(Reg);
|
|
for (const unsigned *AS = TRI->getAliasSet(Reg); *AS; ++AS)
|
|
Uses.set(*AS);
|
|
}
|
|
|
|
MII = PrevMI;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static
|
|
void AssignPhysToVirtReg(MachineInstr *MI, unsigned VirtReg, unsigned PhysReg) {
|
|
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
if (MO.isReg() && MO.getReg() == VirtReg)
|
|
MO.setReg(PhysReg);
|
|
}
|
|
}
|
|
|
|
/// OptimizeByUnfold2 - Unfold a series of load / store folding instructions if
|
|
/// a scratch register is available.
|
|
/// xorq %r12<kill>, %r13
|
|
/// addq %rax, -184(%rbp)
|
|
/// addq %r13, -184(%rbp)
|
|
/// ==>
|
|
/// xorq %r12<kill>, %r13
|
|
/// movq -184(%rbp), %r12
|
|
/// addq %rax, %r12
|
|
/// addq %r13, %r12
|
|
/// movq %r12, -184(%rbp)
|
|
bool LocalSpiller::OptimizeByUnfold2(unsigned VirtReg, int SS,
|
|
MachineBasicBlock &MBB,
|
|
MachineBasicBlock::iterator &MII,
|
|
std::vector<MachineInstr*> &MaybeDeadStores,
|
|
AvailableSpills &Spills,
|
|
BitVector &RegKills,
|
|
std::vector<MachineOperand*> &KillOps,
|
|
VirtRegMap &VRM) {
|
|
MachineBasicBlock::iterator NextMII = next(MII);
|
|
if (NextMII == MBB.end())
|
|
return false;
|
|
|
|
if (TII->getOpcodeAfterMemoryUnfold(MII->getOpcode(), true, true) == 0)
|
|
return false;
|
|
|
|
// Now let's see if the last couple of instructions happens to have freed up
|
|
// a register.
|
|
const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
|
|
unsigned PhysReg = FindFreeRegister(MII, MBB, RC, TRI, AllocatableRegs);
|
|
if (!PhysReg)
|
|
return false;
|
|
|
|
MachineFunction &MF = *MBB.getParent();
|
|
TRI = MF.getTarget().getRegisterInfo();
|
|
MachineInstr &MI = *MII;
|
|
if (!FoldsStackSlotModRef(MI, SS, PhysReg, TII, TRI, VRM))
|
|
return false;
|
|
|
|
// If the next instruction also folds the same SS modref and can be unfoled,
|
|
// then it's worthwhile to issue a load from SS into the free register and
|
|
// then unfold these instructions.
|
|
if (!FoldsStackSlotModRef(*NextMII, SS, PhysReg, TII, TRI, VRM))
|
|
return false;
|
|
|
|
// Load from SS to the spare physical register.
|
|
TII->loadRegFromStackSlot(MBB, MII, PhysReg, SS, RC);
|
|
// This invalidates Phys.
|
|
Spills.ClobberPhysReg(PhysReg);
|
|
// Remember it's available.
|
|
Spills.addAvailable(SS, PhysReg);
|
|
MaybeDeadStores[SS] = NULL;
|
|
|
|
// Unfold current MI.
|
|
SmallVector<MachineInstr*, 4> NewMIs;
|
|
if (!TII->unfoldMemoryOperand(MF, &MI, VirtReg, false, false, NewMIs))
|
|
assert(0 && "Unable unfold the load / store folding instruction!");
|
|
assert(NewMIs.size() == 1);
|
|
AssignPhysToVirtReg(NewMIs[0], VirtReg, PhysReg);
|
|
VRM.transferRestorePts(&MI, NewMIs[0]);
|
|
MII = MBB.insert(MII, NewMIs[0]);
|
|
InvalidateKills(MI, RegKills, KillOps);
|
|
VRM.RemoveMachineInstrFromMaps(&MI);
|
|
MBB.erase(&MI);
|
|
++NumModRefUnfold;
|
|
|
|
// Unfold next instructions that fold the same SS.
|
|
do {
|
|
MachineInstr &NextMI = *NextMII;
|
|
NextMII = next(NextMII);
|
|
NewMIs.clear();
|
|
if (!TII->unfoldMemoryOperand(MF, &NextMI, VirtReg, false, false, NewMIs))
|
|
assert(0 && "Unable unfold the load / store folding instruction!");
|
|
assert(NewMIs.size() == 1);
|
|
AssignPhysToVirtReg(NewMIs[0], VirtReg, PhysReg);
|
|
VRM.transferRestorePts(&NextMI, NewMIs[0]);
|
|
MBB.insert(NextMII, NewMIs[0]);
|
|
InvalidateKills(NextMI, RegKills, KillOps);
|
|
VRM.RemoveMachineInstrFromMaps(&NextMI);
|
|
MBB.erase(&NextMI);
|
|
++NumModRefUnfold;
|
|
} while (FoldsStackSlotModRef(*NextMII, SS, PhysReg, TII, TRI, VRM));
|
|
|
|
// Store the value back into SS.
|
|
TII->storeRegToStackSlot(MBB, NextMII, PhysReg, true, SS, RC);
|
|
MachineInstr *StoreMI = prior(NextMII);
|
|
VRM.addSpillSlotUse(SS, StoreMI);
|
|
VRM.virtFolded(VirtReg, StoreMI, VirtRegMap::isMod);
|
|
|
|
return true;
|
|
}
|
|
|
|
/// OptimizeByUnfold - Turn a store folding instruction into a load folding
|
|
/// instruction. e.g.
|
|
/// xorl %edi, %eax
|
|
/// movl %eax, -32(%ebp)
|
|
/// movl -36(%ebp), %eax
|
|
/// orl %eax, -32(%ebp)
|
|
/// ==>
|
|
/// xorl %edi, %eax
|
|
/// orl -36(%ebp), %eax
|
|
/// mov %eax, -32(%ebp)
|
|
/// This enables unfolding optimization for a subsequent instruction which will
|
|
/// also eliminate the newly introduced store instruction.
|
|
bool LocalSpiller::OptimizeByUnfold(MachineBasicBlock &MBB,
|
|
MachineBasicBlock::iterator &MII,
|
|
std::vector<MachineInstr*> &MaybeDeadStores,
|
|
AvailableSpills &Spills,
|
|
BitVector &RegKills,
|
|
std::vector<MachineOperand*> &KillOps,
|
|
VirtRegMap &VRM) {
|
|
MachineFunction &MF = *MBB.getParent();
|
|
MachineInstr &MI = *MII;
|
|
unsigned UnfoldedOpc = 0;
|
|
unsigned UnfoldPR = 0;
|
|
unsigned UnfoldVR = 0;
|
|
int FoldedSS = VirtRegMap::NO_STACK_SLOT;
|
|
VirtRegMap::MI2VirtMapTy::const_iterator I, End;
|
|
for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ) {
|
|
// Only transform a MI that folds a single register.
|
|
if (UnfoldedOpc)
|
|
return false;
|
|
UnfoldVR = I->second.first;
|
|
VirtRegMap::ModRef MR = I->second.second;
|
|
// MI2VirtMap be can updated which invalidate the iterator.
|
|
// Increment the iterator first.
|
|
++I;
|
|
if (VRM.isAssignedReg(UnfoldVR))
|
|
continue;
|
|
// If this reference is not a use, any previous store is now dead.
|
|
// Otherwise, the store to this stack slot is not dead anymore.
|
|
FoldedSS = VRM.getStackSlot(UnfoldVR);
|
|
MachineInstr* DeadStore = MaybeDeadStores[FoldedSS];
|
|
if (DeadStore && (MR & VirtRegMap::isModRef)) {
|
|
unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(FoldedSS);
|
|
if (!PhysReg || !DeadStore->readsRegister(PhysReg))
|
|
continue;
|
|
UnfoldPR = PhysReg;
|
|
UnfoldedOpc = TII->getOpcodeAfterMemoryUnfold(MI.getOpcode(),
|
|
false, true);
|
|
}
|
|
}
|
|
|
|
if (!UnfoldedOpc) {
|
|
if (!UnfoldVR)
|
|
return false;
|
|
|
|
// Look for other unfolding opportunities.
|
|
return OptimizeByUnfold2(UnfoldVR, FoldedSS, MBB, MII,
|
|
MaybeDeadStores, Spills, RegKills, KillOps, VRM);
|
|
}
|
|
|
|
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI.getOperand(i);
|
|
if (!MO.isReg() || MO.getReg() == 0 || !MO.isUse())
|
|
continue;
|
|
unsigned VirtReg = MO.getReg();
|
|
if (TargetRegisterInfo::isPhysicalRegister(VirtReg) || MO.getSubReg())
|
|
continue;
|
|
if (VRM.isAssignedReg(VirtReg)) {
|
|
unsigned PhysReg = VRM.getPhys(VirtReg);
|
|
if (PhysReg && TRI->regsOverlap(PhysReg, UnfoldPR))
|
|
return false;
|
|
} else if (VRM.isReMaterialized(VirtReg))
|
|
continue;
|
|
int SS = VRM.getStackSlot(VirtReg);
|
|
unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
|
|
if (PhysReg) {
|
|
if (TRI->regsOverlap(PhysReg, UnfoldPR))
|
|
return false;
|
|
continue;
|
|
}
|
|
if (VRM.hasPhys(VirtReg)) {
|
|
PhysReg = VRM.getPhys(VirtReg);
|
|
if (!TRI->regsOverlap(PhysReg, UnfoldPR))
|
|
continue;
|
|
}
|
|
|
|
// Ok, we'll need to reload the value into a register which makes
|
|
// it impossible to perform the store unfolding optimization later.
|
|
// Let's see if it is possible to fold the load if the store is
|
|
// unfolded. This allows us to perform the store unfolding
|
|
// optimization.
|
|
SmallVector<MachineInstr*, 4> NewMIs;
|
|
if (TII->unfoldMemoryOperand(MF, &MI, UnfoldVR, false, false, NewMIs)) {
|
|
assert(NewMIs.size() == 1);
|
|
MachineInstr *NewMI = NewMIs.back();
|
|
NewMIs.clear();
|
|
int Idx = NewMI->findRegisterUseOperandIdx(VirtReg, false);
|
|
assert(Idx != -1);
|
|
SmallVector<unsigned, 1> Ops;
|
|
Ops.push_back(Idx);
|
|
MachineInstr *FoldedMI = TII->foldMemoryOperand(MF, NewMI, Ops, SS);
|
|
if (FoldedMI) {
|
|
VRM.addSpillSlotUse(SS, FoldedMI);
|
|
if (!VRM.hasPhys(UnfoldVR))
|
|
VRM.assignVirt2Phys(UnfoldVR, UnfoldPR);
|
|
VRM.virtFolded(VirtReg, FoldedMI, VirtRegMap::isRef);
|
|
MII = MBB.insert(MII, FoldedMI);
|
|
InvalidateKills(MI, RegKills, KillOps);
|
|
VRM.RemoveMachineInstrFromMaps(&MI);
|
|
MBB.erase(&MI);
|
|
MF.DeleteMachineInstr(NewMI);
|
|
return true;
|
|
}
|
|
MF.DeleteMachineInstr(NewMI);
|
|
}
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/// CommuteToFoldReload -
|
|
/// Look for
|
|
/// r1 = load fi#1
|
|
/// r1 = op r1, r2<kill>
|
|
/// store r1, fi#1
|
|
///
|
|
/// If op is commutable and r2 is killed, then we can xform these to
|
|
/// r2 = op r2, fi#1
|
|
/// store r2, fi#1
|
|
bool LocalSpiller::CommuteToFoldReload(MachineBasicBlock &MBB,
|
|
MachineBasicBlock::iterator &MII,
|
|
unsigned VirtReg, unsigned SrcReg, int SS,
|
|
AvailableSpills &Spills,
|
|
BitVector &RegKills,
|
|
std::vector<MachineOperand*> &KillOps,
|
|
const TargetRegisterInfo *TRI,
|
|
VirtRegMap &VRM) {
|
|
if (MII == MBB.begin() || !MII->killsRegister(SrcReg))
|
|
return false;
|
|
|
|
MachineFunction &MF = *MBB.getParent();
|
|
MachineInstr &MI = *MII;
|
|
MachineBasicBlock::iterator DefMII = prior(MII);
|
|
MachineInstr *DefMI = DefMII;
|
|
const TargetInstrDesc &TID = DefMI->getDesc();
|
|
unsigned NewDstIdx;
|
|
if (DefMII != MBB.begin() &&
|
|
TID.isCommutable() &&
|
|
TII->CommuteChangesDestination(DefMI, NewDstIdx)) {
|
|
MachineOperand &NewDstMO = DefMI->getOperand(NewDstIdx);
|
|
unsigned NewReg = NewDstMO.getReg();
|
|
if (!NewDstMO.isKill() || TRI->regsOverlap(NewReg, SrcReg))
|
|
return false;
|
|
MachineInstr *ReloadMI = prior(DefMII);
|
|
int FrameIdx;
|
|
unsigned DestReg = TII->isLoadFromStackSlot(ReloadMI, FrameIdx);
|
|
if (DestReg != SrcReg || FrameIdx != SS)
|
|
return false;
|
|
int UseIdx = DefMI->findRegisterUseOperandIdx(DestReg, false);
|
|
if (UseIdx == -1)
|
|
return false;
|
|
unsigned DefIdx;
|
|
if (!MI.isRegTiedToDefOperand(UseIdx, &DefIdx))
|
|
return false;
|
|
assert(DefMI->getOperand(DefIdx).isReg() &&
|
|
DefMI->getOperand(DefIdx).getReg() == SrcReg);
|
|
|
|
// Now commute def instruction.
|
|
MachineInstr *CommutedMI = TII->commuteInstruction(DefMI, true);
|
|
if (!CommutedMI)
|
|
return false;
|
|
SmallVector<unsigned, 1> Ops;
|
|
Ops.push_back(NewDstIdx);
|
|
MachineInstr *FoldedMI = TII->foldMemoryOperand(MF, CommutedMI, Ops, SS);
|
|
// Not needed since foldMemoryOperand returns new MI.
|
|
MF.DeleteMachineInstr(CommutedMI);
|
|
if (!FoldedMI)
|
|
return false;
|
|
|
|
VRM.addSpillSlotUse(SS, FoldedMI);
|
|
VRM.virtFolded(VirtReg, FoldedMI, VirtRegMap::isRef);
|
|
// Insert new def MI and spill MI.
|
|
const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
|
|
TII->storeRegToStackSlot(MBB, &MI, NewReg, true, SS, RC);
|
|
MII = prior(MII);
|
|
MachineInstr *StoreMI = MII;
|
|
VRM.addSpillSlotUse(SS, StoreMI);
|
|
VRM.virtFolded(VirtReg, StoreMI, VirtRegMap::isMod);
|
|
MII = MBB.insert(MII, FoldedMI); // Update MII to backtrack.
|
|
|
|
// Delete all 3 old instructions.
|
|
InvalidateKills(*ReloadMI, RegKills, KillOps);
|
|
VRM.RemoveMachineInstrFromMaps(ReloadMI);
|
|
MBB.erase(ReloadMI);
|
|
InvalidateKills(*DefMI, RegKills, KillOps);
|
|
VRM.RemoveMachineInstrFromMaps(DefMI);
|
|
MBB.erase(DefMI);
|
|
InvalidateKills(MI, RegKills, KillOps);
|
|
VRM.RemoveMachineInstrFromMaps(&MI);
|
|
MBB.erase(&MI);
|
|
|
|
// If NewReg was previously holding value of some SS, it's now clobbered.
|
|
// This has to be done now because it's a physical register. When this
|
|
// instruction is re-visited, it's ignored.
|
|
Spills.ClobberPhysReg(NewReg);
|
|
|
|
++NumCommutes;
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/// SpillRegToStackSlot - Spill a register to a specified stack slot. Check if
|
|
/// the last store to the same slot is now dead. If so, remove the last store.
|
|
void LocalSpiller::SpillRegToStackSlot(MachineBasicBlock &MBB,
|
|
MachineBasicBlock::iterator &MII,
|
|
int Idx, unsigned PhysReg, int StackSlot,
|
|
const TargetRegisterClass *RC,
|
|
bool isAvailable, MachineInstr *&LastStore,
|
|
AvailableSpills &Spills,
|
|
SmallSet<MachineInstr*, 4> &ReMatDefs,
|
|
BitVector &RegKills,
|
|
std::vector<MachineOperand*> &KillOps,
|
|
VirtRegMap &VRM) {
|
|
TII->storeRegToStackSlot(MBB, next(MII), PhysReg, true, StackSlot, RC);
|
|
MachineInstr *StoreMI = next(MII);
|
|
VRM.addSpillSlotUse(StackSlot, StoreMI);
|
|
DOUT << "Store:\t" << *StoreMI;
|
|
|
|
// If there is a dead store to this stack slot, nuke it now.
|
|
if (LastStore) {
|
|
DOUT << "Removed dead store:\t" << *LastStore;
|
|
++NumDSE;
|
|
SmallVector<unsigned, 2> KillRegs;
|
|
InvalidateKills(*LastStore, RegKills, KillOps, &KillRegs);
|
|
MachineBasicBlock::iterator PrevMII = LastStore;
|
|
bool CheckDef = PrevMII != MBB.begin();
|
|
if (CheckDef)
|
|
--PrevMII;
|
|
VRM.RemoveMachineInstrFromMaps(LastStore);
|
|
MBB.erase(LastStore);
|
|
if (CheckDef) {
|
|
// Look at defs of killed registers on the store. Mark the defs
|
|
// as dead since the store has been deleted and they aren't
|
|
// being reused.
|
|
for (unsigned j = 0, ee = KillRegs.size(); j != ee; ++j) {
|
|
bool HasOtherDef = false;
|
|
if (InvalidateRegDef(PrevMII, *MII, KillRegs[j], HasOtherDef)) {
|
|
MachineInstr *DeadDef = PrevMII;
|
|
if (ReMatDefs.count(DeadDef) && !HasOtherDef) {
|
|
// FIXME: This assumes a remat def does not have side
|
|
// effects.
|
|
VRM.RemoveMachineInstrFromMaps(DeadDef);
|
|
MBB.erase(DeadDef);
|
|
++NumDRM;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
LastStore = next(MII);
|
|
|
|
// If the stack slot value was previously available in some other
|
|
// register, change it now. Otherwise, make the register available,
|
|
// in PhysReg.
|
|
Spills.ModifyStackSlotOrReMat(StackSlot);
|
|
Spills.ClobberPhysReg(PhysReg);
|
|
Spills.addAvailable(StackSlot, PhysReg, isAvailable);
|
|
++NumStores;
|
|
}
|
|
|
|
/// TransferDeadness - A identity copy definition is dead and it's being
|
|
/// removed. Find the last def or use and mark it as dead / kill.
|
|
void LocalSpiller::TransferDeadness(MachineBasicBlock *MBB, unsigned CurDist,
|
|
unsigned Reg, BitVector &RegKills,
|
|
std::vector<MachineOperand*> &KillOps) {
|
|
int LastUDDist = -1;
|
|
MachineInstr *LastUDMI = NULL;
|
|
for (MachineRegisterInfo::reg_iterator RI = RegInfo->reg_begin(Reg),
|
|
RE = RegInfo->reg_end(); RI != RE; ++RI) {
|
|
MachineInstr *UDMI = &*RI;
|
|
if (UDMI->getParent() != MBB)
|
|
continue;
|
|
DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(UDMI);
|
|
if (DI == DistanceMap.end() || DI->second > CurDist)
|
|
continue;
|
|
if ((int)DI->second < LastUDDist)
|
|
continue;
|
|
LastUDDist = DI->second;
|
|
LastUDMI = UDMI;
|
|
}
|
|
|
|
if (LastUDMI) {
|
|
MachineOperand *LastUD = NULL;
|
|
for (unsigned i = 0, e = LastUDMI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = LastUDMI->getOperand(i);
|
|
if (!MO.isReg() || MO.getReg() != Reg)
|
|
continue;
|
|
if (!LastUD || (LastUD->isUse() && MO.isDef()))
|
|
LastUD = &MO;
|
|
if (LastUDMI->isRegTiedToDefOperand(i))
|
|
return;
|
|
}
|
|
if (LastUD->isDef())
|
|
LastUD->setIsDead();
|
|
else {
|
|
LastUD->setIsKill();
|
|
RegKills.set(Reg);
|
|
KillOps[Reg] = LastUD;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// rewriteMBB - Keep track of which spills are available even after the
|
|
/// register allocator is done with them. If possible, avid reloading vregs.
|
|
void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM,
|
|
LiveIntervals *LIs,
|
|
AvailableSpills &Spills, BitVector &RegKills,
|
|
std::vector<MachineOperand*> &KillOps) {
|
|
DOUT << "\n**** Local spiller rewriting MBB '"
|
|
<< MBB.getBasicBlock()->getName() << "':\n";
|
|
|
|
MachineFunction &MF = *MBB.getParent();
|
|
|
|
// MaybeDeadStores - When we need to write a value back into a stack slot,
|
|
// keep track of the inserted store. If the stack slot value is never read
|
|
// (because the value was used from some available register, for example), and
|
|
// subsequently stored to, the original store is dead. This map keeps track
|
|
// of inserted stores that are not used. If we see a subsequent store to the
|
|
// same stack slot, the original store is deleted.
|
|
std::vector<MachineInstr*> MaybeDeadStores;
|
|
MaybeDeadStores.resize(MF.getFrameInfo()->getObjectIndexEnd(), NULL);
|
|
|
|
// ReMatDefs - These are rematerializable def MIs which are not deleted.
|
|
SmallSet<MachineInstr*, 4> ReMatDefs;
|
|
|
|
// Clear kill info.
|
|
SmallSet<unsigned, 2> KilledMIRegs;
|
|
RegKills.reset();
|
|
KillOps.clear();
|
|
KillOps.resize(TRI->getNumRegs(), NULL);
|
|
|
|
unsigned Dist = 0;
|
|
DistanceMap.clear();
|
|
for (MachineBasicBlock::iterator MII = MBB.begin(), E = MBB.end();
|
|
MII != E; ) {
|
|
MachineBasicBlock::iterator NextMII = next(MII);
|
|
|
|
VirtRegMap::MI2VirtMapTy::const_iterator I, End;
|
|
bool Erased = false;
|
|
bool BackTracked = false;
|
|
if (OptimizeByUnfold(MBB, MII,
|
|
MaybeDeadStores, Spills, RegKills, KillOps, VRM))
|
|
NextMII = next(MII);
|
|
|
|
MachineInstr &MI = *MII;
|
|
|
|
if (VRM.hasEmergencySpills(&MI)) {
|
|
// Spill physical register(s) in the rare case the allocator has run out
|
|
// of registers to allocate.
|
|
SmallSet<int, 4> UsedSS;
|
|
std::vector<unsigned> &EmSpills = VRM.getEmergencySpills(&MI);
|
|
for (unsigned i = 0, e = EmSpills.size(); i != e; ++i) {
|
|
unsigned PhysReg = EmSpills[i];
|
|
const TargetRegisterClass *RC =
|
|
TRI->getPhysicalRegisterRegClass(PhysReg);
|
|
assert(RC && "Unable to determine register class!");
|
|
int SS = VRM.getEmergencySpillSlot(RC);
|
|
if (UsedSS.count(SS))
|
|
assert(0 && "Need to spill more than one physical registers!");
|
|
UsedSS.insert(SS);
|
|
TII->storeRegToStackSlot(MBB, MII, PhysReg, true, SS, RC);
|
|
MachineInstr *StoreMI = prior(MII);
|
|
VRM.addSpillSlotUse(SS, StoreMI);
|
|
TII->loadRegFromStackSlot(MBB, next(MII), PhysReg, SS, RC);
|
|
MachineInstr *LoadMI = next(MII);
|
|
VRM.addSpillSlotUse(SS, LoadMI);
|
|
++NumPSpills;
|
|
}
|
|
NextMII = next(MII);
|
|
}
|
|
|
|
// Insert restores here if asked to.
|
|
if (VRM.isRestorePt(&MI)) {
|
|
std::vector<unsigned> &RestoreRegs = VRM.getRestorePtRestores(&MI);
|
|
for (unsigned i = 0, e = RestoreRegs.size(); i != e; ++i) {
|
|
unsigned VirtReg = RestoreRegs[e-i-1]; // Reverse order.
|
|
if (!VRM.getPreSplitReg(VirtReg))
|
|
continue; // Split interval spilled again.
|
|
unsigned Phys = VRM.getPhys(VirtReg);
|
|
RegInfo->setPhysRegUsed(Phys);
|
|
|
|
// Check if the value being restored if available. If so, it must be
|
|
// from a predecessor BB that fallthrough into this BB. We do not
|
|
// expect:
|
|
// BB1:
|
|
// r1 = load fi#1
|
|
// ...
|
|
// = r1<kill>
|
|
// ... # r1 not clobbered
|
|
// ...
|
|
// = load fi#1
|
|
bool DoReMat = VRM.isReMaterialized(VirtReg);
|
|
int SSorRMId = DoReMat
|
|
? VRM.getReMatId(VirtReg) : VRM.getStackSlot(VirtReg);
|
|
const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
|
|
unsigned InReg = Spills.getSpillSlotOrReMatPhysReg(SSorRMId);
|
|
if (InReg == Phys) {
|
|
// If the value is already available in the expected register, save
|
|
// a reload / remat.
|
|
if (SSorRMId)
|
|
DOUT << "Reusing RM#" << SSorRMId-VirtRegMap::MAX_STACK_SLOT-1;
|
|
else
|
|
DOUT << "Reusing SS#" << SSorRMId;
|
|
DOUT << " from physreg "
|
|
<< TRI->getName(InReg) << " for vreg"
|
|
<< VirtReg <<" instead of reloading into physreg "
|
|
<< TRI->getName(Phys) << "\n";
|
|
++NumOmitted;
|
|
continue;
|
|
} else if (InReg && InReg != Phys) {
|
|
if (SSorRMId)
|
|
DOUT << "Reusing RM#" << SSorRMId-VirtRegMap::MAX_STACK_SLOT-1;
|
|
else
|
|
DOUT << "Reusing SS#" << SSorRMId;
|
|
DOUT << " from physreg "
|
|
<< TRI->getName(InReg) << " for vreg"
|
|
<< VirtReg <<" by copying it into physreg "
|
|
<< TRI->getName(Phys) << "\n";
|
|
|
|
// If the reloaded / remat value is available in another register,
|
|
// copy it to the desired register.
|
|
TII->copyRegToReg(MBB, &MI, Phys, InReg, RC, RC);
|
|
|
|
// This invalidates Phys.
|
|
Spills.ClobberPhysReg(Phys);
|
|
// Remember it's available.
|
|
Spills.addAvailable(SSorRMId, Phys);
|
|
|
|
// Mark is killed.
|
|
MachineInstr *CopyMI = prior(MII);
|
|
MachineOperand *KillOpnd = CopyMI->findRegisterUseOperand(InReg);
|
|
KillOpnd->setIsKill();
|
|
UpdateKills(*CopyMI, RegKills, KillOps, TRI);
|
|
|
|
DOUT << '\t' << *CopyMI;
|
|
++NumCopified;
|
|
continue;
|
|
}
|
|
|
|
if (VRM.isReMaterialized(VirtReg)) {
|
|
ReMaterialize(MBB, MII, Phys, VirtReg, TII, TRI, VRM);
|
|
} else {
|
|
const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
|
|
TII->loadRegFromStackSlot(MBB, &MI, Phys, SSorRMId, RC);
|
|
MachineInstr *LoadMI = prior(MII);
|
|
VRM.addSpillSlotUse(SSorRMId, LoadMI);
|
|
++NumLoads;
|
|
}
|
|
|
|
// This invalidates Phys.
|
|
Spills.ClobberPhysReg(Phys);
|
|
// Remember it's available.
|
|
Spills.addAvailable(SSorRMId, Phys);
|
|
|
|
UpdateKills(*prior(MII), RegKills, KillOps, TRI);
|
|
DOUT << '\t' << *prior(MII);
|
|
}
|
|
}
|
|
|
|
// Insert spills here if asked to.
|
|
if (VRM.isSpillPt(&MI)) {
|
|
std::vector<std::pair<unsigned,bool> > &SpillRegs =
|
|
VRM.getSpillPtSpills(&MI);
|
|
for (unsigned i = 0, e = SpillRegs.size(); i != e; ++i) {
|
|
unsigned VirtReg = SpillRegs[i].first;
|
|
bool isKill = SpillRegs[i].second;
|
|
if (!VRM.getPreSplitReg(VirtReg))
|
|
continue; // Split interval spilled again.
|
|
const TargetRegisterClass *RC = RegInfo->getRegClass(VirtReg);
|
|
unsigned Phys = VRM.getPhys(VirtReg);
|
|
int StackSlot = VRM.getStackSlot(VirtReg);
|
|
TII->storeRegToStackSlot(MBB, next(MII), Phys, isKill, StackSlot, RC);
|
|
MachineInstr *StoreMI = next(MII);
|
|
VRM.addSpillSlotUse(StackSlot, StoreMI);
|
|
DOUT << "Store:\t" << *StoreMI;
|
|
VRM.virtFolded(VirtReg, StoreMI, VirtRegMap::isMod);
|
|
}
|
|
NextMII = next(MII);
|
|
}
|
|
|
|
/// ReusedOperands - Keep track of operand reuse in case we need to undo
|
|
/// reuse.
|
|
ReuseInfo ReusedOperands(MI, TRI);
|
|
SmallVector<unsigned, 4> VirtUseOps;
|
|
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI.getOperand(i);
|
|
if (!MO.isReg() || MO.getReg() == 0)
|
|
continue; // Ignore non-register operands.
|
|
|
|
unsigned VirtReg = MO.getReg();
|
|
if (TargetRegisterInfo::isPhysicalRegister(VirtReg)) {
|
|
// Ignore physregs for spilling, but remember that it is used by this
|
|
// function.
|
|
RegInfo->setPhysRegUsed(VirtReg);
|
|
continue;
|
|
}
|
|
|
|
// We want to process implicit virtual register uses first.
|
|
if (MO.isImplicit())
|
|
// If the virtual register is implicitly defined, emit a implicit_def
|
|
// before so scavenger knows it's "defined".
|
|
VirtUseOps.insert(VirtUseOps.begin(), i);
|
|
else
|
|
VirtUseOps.push_back(i);
|
|
}
|
|
|
|
// Process all of the spilled uses and all non spilled reg references.
|
|
SmallVector<int, 2> PotentialDeadStoreSlots;
|
|
KilledMIRegs.clear();
|
|
for (unsigned j = 0, e = VirtUseOps.size(); j != e; ++j) {
|
|
unsigned i = VirtUseOps[j];
|
|
MachineOperand &MO = MI.getOperand(i);
|
|
unsigned VirtReg = MO.getReg();
|
|
assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
|
|
"Not a virtual register?");
|
|
|
|
unsigned SubIdx = MO.getSubReg();
|
|
if (VRM.isAssignedReg(VirtReg)) {
|
|
// This virtual register was assigned a physreg!
|
|
unsigned Phys = VRM.getPhys(VirtReg);
|
|
RegInfo->setPhysRegUsed(Phys);
|
|
if (MO.isDef())
|
|
ReusedOperands.markClobbered(Phys);
|
|
unsigned RReg = SubIdx ? TRI->getSubReg(Phys, SubIdx) : Phys;
|
|
MI.getOperand(i).setReg(RReg);
|
|
MI.getOperand(i).setSubReg(0);
|
|
if (VRM.isImplicitlyDefined(VirtReg))
|
|
BuildMI(MBB, &MI, MI.getDebugLoc(),
|
|
TII->get(TargetInstrInfo::IMPLICIT_DEF), RReg);
|
|
continue;
|
|
}
|
|
|
|
// This virtual register is now known to be a spilled value.
|
|
if (!MO.isUse())
|
|
continue; // Handle defs in the loop below (handle use&def here though)
|
|
|
|
bool AvoidReload = false;
|
|
if (LIs->hasInterval(VirtReg)) {
|
|
LiveInterval &LI = LIs->getInterval(VirtReg);
|
|
if (!LI.liveAt(LIs->getUseIndex(LI.beginNumber())))
|
|
// Must be defined by an implicit def. It should not be spilled. Note,
|
|
// this is for correctness reason. e.g.
|
|
// 8 %reg1024<def> = IMPLICIT_DEF
|
|
// 12 %reg1024<def> = INSERT_SUBREG %reg1024<kill>, %reg1025, 2
|
|
// The live range [12, 14) are not part of the r1024 live interval since
|
|
// it's defined by an implicit def. It will not conflicts with live
|
|
// interval of r1025. Now suppose both registers are spilled, you can
|
|
// easily see a situation where both registers are reloaded before
|
|
// the INSERT_SUBREG and both target registers that would overlap.
|
|
AvoidReload = true;
|
|
}
|
|
|
|
bool DoReMat = VRM.isReMaterialized(VirtReg);
|
|
int SSorRMId = DoReMat
|
|
? VRM.getReMatId(VirtReg) : VRM.getStackSlot(VirtReg);
|
|
int ReuseSlot = SSorRMId;
|
|
|
|
// Check to see if this stack slot is available.
|
|
unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SSorRMId);
|
|
|
|
// If this is a sub-register use, make sure the reuse register is in the
|
|
// right register class. For example, for x86 not all of the 32-bit
|
|
// registers have accessible sub-registers.
|
|
// Similarly so for EXTRACT_SUBREG. Consider this:
|
|
// EDI = op
|
|
// MOV32_mr fi#1, EDI
|
|
// ...
|
|
// = EXTRACT_SUBREG fi#1
|
|
// fi#1 is available in EDI, but it cannot be reused because it's not in
|
|
// the right register file.
|
|
if (PhysReg && !AvoidReload &&
|
|
(SubIdx || MI.getOpcode() == TargetInstrInfo::EXTRACT_SUBREG)) {
|
|
const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
|
|
if (!RC->contains(PhysReg))
|
|
PhysReg = 0;
|
|
}
|
|
|
|
if (PhysReg && !AvoidReload) {
|
|
// This spilled operand might be part of a two-address operand. If this
|
|
// is the case, then changing it will necessarily require changing the
|
|
// def part of the instruction as well. However, in some cases, we
|
|
// aren't allowed to modify the reused register. If none of these cases
|
|
// apply, reuse it.
|
|
bool CanReuse = true;
|
|
bool isTied = MI.isRegTiedToDefOperand(i);
|
|
if (isTied) {
|
|
// Okay, we have a two address operand. We can reuse this physreg as
|
|
// long as we are allowed to clobber the value and there isn't an
|
|
// earlier def that has already clobbered the physreg.
|
|
CanReuse = !ReusedOperands.isClobbered(PhysReg) &&
|
|
Spills.canClobberPhysReg(PhysReg);
|
|
}
|
|
|
|
if (CanReuse) {
|
|
// If this stack slot value is already available, reuse it!
|
|
if (ReuseSlot > VirtRegMap::MAX_STACK_SLOT)
|
|
DOUT << "Reusing RM#" << ReuseSlot-VirtRegMap::MAX_STACK_SLOT-1;
|
|
else
|
|
DOUT << "Reusing SS#" << ReuseSlot;
|
|
DOUT << " from physreg "
|
|
<< TRI->getName(PhysReg) << " for vreg"
|
|
<< VirtReg <<" instead of reloading into physreg "
|
|
<< TRI->getName(VRM.getPhys(VirtReg)) << "\n";
|
|
unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg;
|
|
MI.getOperand(i).setReg(RReg);
|
|
MI.getOperand(i).setSubReg(0);
|
|
|
|
// The only technical detail we have is that we don't know that
|
|
// PhysReg won't be clobbered by a reloaded stack slot that occurs
|
|
// later in the instruction. In particular, consider 'op V1, V2'.
|
|
// If V1 is available in physreg R0, we would choose to reuse it
|
|
// here, instead of reloading it into the register the allocator
|
|
// indicated (say R1). However, V2 might have to be reloaded
|
|
// later, and it might indicate that it needs to live in R0. When
|
|
// this occurs, we need to have information available that
|
|
// indicates it is safe to use R1 for the reload instead of R0.
|
|
//
|
|
// To further complicate matters, we might conflict with an alias,
|
|
// or R0 and R1 might not be compatible with each other. In this
|
|
// case, we actually insert a reload for V1 in R1, ensuring that
|
|
// we can get at R0 or its alias.
|
|
ReusedOperands.addReuse(i, ReuseSlot, PhysReg,
|
|
VRM.getPhys(VirtReg), VirtReg);
|
|
if (isTied)
|
|
// Only mark it clobbered if this is a use&def operand.
|
|
ReusedOperands.markClobbered(PhysReg);
|
|
++NumReused;
|
|
|
|
if (MI.getOperand(i).isKill() &&
|
|
ReuseSlot <= VirtRegMap::MAX_STACK_SLOT) {
|
|
|
|
// The store of this spilled value is potentially dead, but we
|
|
// won't know for certain until we've confirmed that the re-use
|
|
// above is valid, which means waiting until the other operands
|
|
// are processed. For now we just track the spill slot, we'll
|
|
// remove it after the other operands are processed if valid.
|
|
|
|
PotentialDeadStoreSlots.push_back(ReuseSlot);
|
|
}
|
|
|
|
// Mark is isKill if it's there no other uses of the same virtual
|
|
// register and it's not a two-address operand. IsKill will be
|
|
// unset if reg is reused.
|
|
if (!isTied && KilledMIRegs.count(VirtReg) == 0) {
|
|
MI.getOperand(i).setIsKill();
|
|
KilledMIRegs.insert(VirtReg);
|
|
}
|
|
|
|
continue;
|
|
} // CanReuse
|
|
|
|
// Otherwise we have a situation where we have a two-address instruction
|
|
// whose mod/ref operand needs to be reloaded. This reload is already
|
|
// available in some register "PhysReg", but if we used PhysReg as the
|
|
// operand to our 2-addr instruction, the instruction would modify
|
|
// PhysReg. This isn't cool if something later uses PhysReg and expects
|
|
// to get its initial value.
|
|
//
|
|
// To avoid this problem, and to avoid doing a load right after a store,
|
|
// we emit a copy from PhysReg into the designated register for this
|
|
// operand.
|
|
unsigned DesignatedReg = VRM.getPhys(VirtReg);
|
|
assert(DesignatedReg && "Must map virtreg to physreg!");
|
|
|
|
// Note that, if we reused a register for a previous operand, the
|
|
// register we want to reload into might not actually be
|
|
// available. If this occurs, use the register indicated by the
|
|
// reuser.
|
|
if (ReusedOperands.hasReuses())
|
|
DesignatedReg = ReusedOperands.GetRegForReload(DesignatedReg, &MI,
|
|
Spills, MaybeDeadStores, RegKills, KillOps, VRM);
|
|
|
|
// If the mapped designated register is actually the physreg we have
|
|
// incoming, we don't need to inserted a dead copy.
|
|
if (DesignatedReg == PhysReg) {
|
|
// If this stack slot value is already available, reuse it!
|
|
if (ReuseSlot > VirtRegMap::MAX_STACK_SLOT)
|
|
DOUT << "Reusing RM#" << ReuseSlot-VirtRegMap::MAX_STACK_SLOT-1;
|
|
else
|
|
DOUT << "Reusing SS#" << ReuseSlot;
|
|
DOUT << " from physreg " << TRI->getName(PhysReg)
|
|
<< " for vreg" << VirtReg
|
|
<< " instead of reloading into same physreg.\n";
|
|
unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg;
|
|
MI.getOperand(i).setReg(RReg);
|
|
MI.getOperand(i).setSubReg(0);
|
|
ReusedOperands.markClobbered(RReg);
|
|
++NumReused;
|
|
continue;
|
|
}
|
|
|
|
const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
|
|
RegInfo->setPhysRegUsed(DesignatedReg);
|
|
ReusedOperands.markClobbered(DesignatedReg);
|
|
TII->copyRegToReg(MBB, &MI, DesignatedReg, PhysReg, RC, RC);
|
|
|
|
MachineInstr *CopyMI = prior(MII);
|
|
UpdateKills(*CopyMI, RegKills, KillOps, TRI);
|
|
|
|
// This invalidates DesignatedReg.
|
|
Spills.ClobberPhysReg(DesignatedReg);
|
|
|
|
Spills.addAvailable(ReuseSlot, DesignatedReg);
|
|
unsigned RReg =
|
|
SubIdx ? TRI->getSubReg(DesignatedReg, SubIdx) : DesignatedReg;
|
|
MI.getOperand(i).setReg(RReg);
|
|
MI.getOperand(i).setSubReg(0);
|
|
DOUT << '\t' << *prior(MII);
|
|
++NumReused;
|
|
continue;
|
|
} // if (PhysReg)
|
|
|
|
// Otherwise, reload it and remember that we have it.
|
|
PhysReg = VRM.getPhys(VirtReg);
|
|
assert(PhysReg && "Must map virtreg to physreg!");
|
|
|
|
// Note that, if we reused a register for a previous operand, the
|
|
// register we want to reload into might not actually be
|
|
// available. If this occurs, use the register indicated by the
|
|
// reuser.
|
|
if (ReusedOperands.hasReuses())
|
|
PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI,
|
|
Spills, MaybeDeadStores, RegKills, KillOps, VRM);
|
|
|
|
RegInfo->setPhysRegUsed(PhysReg);
|
|
ReusedOperands.markClobbered(PhysReg);
|
|
if (AvoidReload)
|
|
++NumAvoided;
|
|
else {
|
|
if (DoReMat) {
|
|
ReMaterialize(MBB, MII, PhysReg, VirtReg, TII, TRI, VRM);
|
|
} else {
|
|
const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
|
|
TII->loadRegFromStackSlot(MBB, &MI, PhysReg, SSorRMId, RC);
|
|
MachineInstr *LoadMI = prior(MII);
|
|
VRM.addSpillSlotUse(SSorRMId, LoadMI);
|
|
++NumLoads;
|
|
}
|
|
// This invalidates PhysReg.
|
|
Spills.ClobberPhysReg(PhysReg);
|
|
|
|
// Any stores to this stack slot are not dead anymore.
|
|
if (!DoReMat)
|
|
MaybeDeadStores[SSorRMId] = NULL;
|
|
Spills.addAvailable(SSorRMId, PhysReg);
|
|
// Assumes this is the last use. IsKill will be unset if reg is reused
|
|
// unless it's a two-address operand.
|
|
if (!MI.isRegTiedToDefOperand(i) &&
|
|
KilledMIRegs.count(VirtReg) == 0) {
|
|
MI.getOperand(i).setIsKill();
|
|
KilledMIRegs.insert(VirtReg);
|
|
}
|
|
|
|
UpdateKills(*prior(MII), RegKills, KillOps, TRI);
|
|
DOUT << '\t' << *prior(MII);
|
|
}
|
|
unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg;
|
|
MI.getOperand(i).setReg(RReg);
|
|
MI.getOperand(i).setSubReg(0);
|
|
}
|
|
|
|
// Ok - now we can remove stores that have been confirmed dead.
|
|
for (unsigned j = 0, e = PotentialDeadStoreSlots.size(); j != e; ++j) {
|
|
// This was the last use and the spilled value is still available
|
|
// for reuse. That means the spill was unnecessary!
|
|
int PDSSlot = PotentialDeadStoreSlots[j];
|
|
MachineInstr* DeadStore = MaybeDeadStores[PDSSlot];
|
|
if (DeadStore) {
|
|
DOUT << "Removed dead store:\t" << *DeadStore;
|
|
InvalidateKills(*DeadStore, RegKills, KillOps);
|
|
VRM.RemoveMachineInstrFromMaps(DeadStore);
|
|
MBB.erase(DeadStore);
|
|
MaybeDeadStores[PDSSlot] = NULL;
|
|
++NumDSE;
|
|
}
|
|
}
|
|
|
|
|
|
DOUT << '\t' << MI;
|
|
|
|
|
|
// If we have folded references to memory operands, make sure we clear all
|
|
// physical registers that may contain the value of the spilled virtual
|
|
// register
|
|
SmallSet<int, 2> FoldedSS;
|
|
for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ) {
|
|
unsigned VirtReg = I->second.first;
|
|
VirtRegMap::ModRef MR = I->second.second;
|
|
DOUT << "Folded vreg: " << VirtReg << " MR: " << MR;
|
|
|
|
// MI2VirtMap be can updated which invalidate the iterator.
|
|
// Increment the iterator first.
|
|
++I;
|
|
int SS = VRM.getStackSlot(VirtReg);
|
|
if (SS == VirtRegMap::NO_STACK_SLOT)
|
|
continue;
|
|
FoldedSS.insert(SS);
|
|
DOUT << " - StackSlot: " << SS << "\n";
|
|
|
|
// If this folded instruction is just a use, check to see if it's a
|
|
// straight load from the virt reg slot.
|
|
if ((MR & VirtRegMap::isRef) && !(MR & VirtRegMap::isMod)) {
|
|
int FrameIdx;
|
|
unsigned DestReg = TII->isLoadFromStackSlot(&MI, FrameIdx);
|
|
if (DestReg && FrameIdx == SS) {
|
|
// If this spill slot is available, turn it into a copy (or nothing)
|
|
// instead of leaving it as a load!
|
|
if (unsigned InReg = Spills.getSpillSlotOrReMatPhysReg(SS)) {
|
|
DOUT << "Promoted Load To Copy: " << MI;
|
|
if (DestReg != InReg) {
|
|
const TargetRegisterClass *RC = RegInfo->getRegClass(VirtReg);
|
|
TII->copyRegToReg(MBB, &MI, DestReg, InReg, RC, RC);
|
|
MachineOperand *DefMO = MI.findRegisterDefOperand(DestReg);
|
|
unsigned SubIdx = DefMO->getSubReg();
|
|
// Revisit the copy so we make sure to notice the effects of the
|
|
// operation on the destreg (either needing to RA it if it's
|
|
// virtual or needing to clobber any values if it's physical).
|
|
NextMII = &MI;
|
|
--NextMII; // backtrack to the copy.
|
|
// Propagate the sub-register index over.
|
|
if (SubIdx) {
|
|
DefMO = NextMII->findRegisterDefOperand(DestReg);
|
|
DefMO->setSubReg(SubIdx);
|
|
}
|
|
|
|
// Mark is killed.
|
|
MachineOperand *KillOpnd = NextMII->findRegisterUseOperand(InReg);
|
|
KillOpnd->setIsKill();
|
|
|
|
BackTracked = true;
|
|
} else {
|
|
DOUT << "Removing now-noop copy: " << MI;
|
|
// Unset last kill since it's being reused.
|
|
InvalidateKill(InReg, RegKills, KillOps);
|
|
Spills.disallowClobberPhysReg(InReg);
|
|
}
|
|
|
|
InvalidateKills(MI, RegKills, KillOps);
|
|
VRM.RemoveMachineInstrFromMaps(&MI);
|
|
MBB.erase(&MI);
|
|
Erased = true;
|
|
goto ProcessNextInst;
|
|
}
|
|
} else {
|
|
unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
|
|
SmallVector<MachineInstr*, 4> NewMIs;
|
|
if (PhysReg &&
|
|
TII->unfoldMemoryOperand(MF, &MI, PhysReg, false, false, NewMIs)) {
|
|
MBB.insert(MII, NewMIs[0]);
|
|
InvalidateKills(MI, RegKills, KillOps);
|
|
VRM.RemoveMachineInstrFromMaps(&MI);
|
|
MBB.erase(&MI);
|
|
Erased = true;
|
|
--NextMII; // backtrack to the unfolded instruction.
|
|
BackTracked = true;
|
|
goto ProcessNextInst;
|
|
}
|
|
}
|
|
}
|
|
|
|
// If this reference is not a use, any previous store is now dead.
|
|
// Otherwise, the store to this stack slot is not dead anymore.
|
|
MachineInstr* DeadStore = MaybeDeadStores[SS];
|
|
if (DeadStore) {
|
|
bool isDead = !(MR & VirtRegMap::isRef);
|
|
MachineInstr *NewStore = NULL;
|
|
if (MR & VirtRegMap::isModRef) {
|
|
unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
|
|
SmallVector<MachineInstr*, 4> NewMIs;
|
|
// We can reuse this physreg as long as we are allowed to clobber
|
|
// the value and there isn't an earlier def that has already clobbered
|
|
// the physreg.
|
|
if (PhysReg &&
|
|
!ReusedOperands.isClobbered(PhysReg) &&
|
|
Spills.canClobberPhysReg(PhysReg) &&
|
|
!TII->isStoreToStackSlot(&MI, SS)) { // Not profitable!
|
|
MachineOperand *KillOpnd =
|
|
DeadStore->findRegisterUseOperand(PhysReg, true);
|
|
// Note, if the store is storing a sub-register, it's possible the
|
|
// super-register is needed below.
|
|
if (KillOpnd && !KillOpnd->getSubReg() &&
|
|
TII->unfoldMemoryOperand(MF, &MI, PhysReg, false, true,NewMIs)){
|
|
MBB.insert(MII, NewMIs[0]);
|
|
NewStore = NewMIs[1];
|
|
MBB.insert(MII, NewStore);
|
|
VRM.addSpillSlotUse(SS, NewStore);
|
|
InvalidateKills(MI, RegKills, KillOps);
|
|
VRM.RemoveMachineInstrFromMaps(&MI);
|
|
MBB.erase(&MI);
|
|
Erased = true;
|
|
--NextMII;
|
|
--NextMII; // backtrack to the unfolded instruction.
|
|
BackTracked = true;
|
|
isDead = true;
|
|
++NumSUnfold;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (isDead) { // Previous store is dead.
|
|
// If we get here, the store is dead, nuke it now.
|
|
DOUT << "Removed dead store:\t" << *DeadStore;
|
|
InvalidateKills(*DeadStore, RegKills, KillOps);
|
|
VRM.RemoveMachineInstrFromMaps(DeadStore);
|
|
MBB.erase(DeadStore);
|
|
if (!NewStore)
|
|
++NumDSE;
|
|
}
|
|
|
|
MaybeDeadStores[SS] = NULL;
|
|
if (NewStore) {
|
|
// Treat this store as a spill merged into a copy. That makes the
|
|
// stack slot value available.
|
|
VRM.virtFolded(VirtReg, NewStore, VirtRegMap::isMod);
|
|
goto ProcessNextInst;
|
|
}
|
|
}
|
|
|
|
// If the spill slot value is available, and this is a new definition of
|
|
// the value, the value is not available anymore.
|
|
if (MR & VirtRegMap::isMod) {
|
|
// Notice that the value in this stack slot has been modified.
|
|
Spills.ModifyStackSlotOrReMat(SS);
|
|
|
|
// If this is *just* a mod of the value, check to see if this is just a
|
|
// store to the spill slot (i.e. the spill got merged into the copy). If
|
|
// so, realize that the vreg is available now, and add the store to the
|
|
// MaybeDeadStore info.
|
|
int StackSlot;
|
|
if (!(MR & VirtRegMap::isRef)) {
|
|
if (unsigned SrcReg = TII->isStoreToStackSlot(&MI, StackSlot)) {
|
|
assert(TargetRegisterInfo::isPhysicalRegister(SrcReg) &&
|
|
"Src hasn't been allocated yet?");
|
|
|
|
if (CommuteToFoldReload(MBB, MII, VirtReg, SrcReg, StackSlot,
|
|
Spills, RegKills, KillOps, TRI, VRM)) {
|
|
NextMII = next(MII);
|
|
BackTracked = true;
|
|
goto ProcessNextInst;
|
|
}
|
|
|
|
// Okay, this is certainly a store of SrcReg to [StackSlot]. Mark
|
|
// this as a potentially dead store in case there is a subsequent
|
|
// store into the stack slot without a read from it.
|
|
MaybeDeadStores[StackSlot] = &MI;
|
|
|
|
// If the stack slot value was previously available in some other
|
|
// register, change it now. Otherwise, make the register
|
|
// available in PhysReg.
|
|
Spills.addAvailable(StackSlot, SrcReg, MI.killsRegister(SrcReg));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Process all of the spilled defs.
|
|
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI.getOperand(i);
|
|
if (!(MO.isReg() && MO.getReg() && MO.isDef()))
|
|
continue;
|
|
|
|
unsigned VirtReg = MO.getReg();
|
|
if (!TargetRegisterInfo::isVirtualRegister(VirtReg)) {
|
|
// Check to see if this is a noop copy. If so, eliminate the
|
|
// instruction before considering the dest reg to be changed.
|
|
unsigned Src, Dst, SrcSR, DstSR;
|
|
if (TII->isMoveInstr(MI, Src, Dst, SrcSR, DstSR) && Src == Dst) {
|
|
++NumDCE;
|
|
DOUT << "Removing now-noop copy: " << MI;
|
|
SmallVector<unsigned, 2> KillRegs;
|
|
InvalidateKills(MI, RegKills, KillOps, &KillRegs);
|
|
if (MO.isDead() && !KillRegs.empty()) {
|
|
// Source register or an implicit super/sub-register use is killed.
|
|
assert(KillRegs[0] == Dst ||
|
|
TRI->isSubRegister(KillRegs[0], Dst) ||
|
|
TRI->isSuperRegister(KillRegs[0], Dst));
|
|
// Last def is now dead.
|
|
TransferDeadness(&MBB, Dist, Src, RegKills, KillOps);
|
|
}
|
|
VRM.RemoveMachineInstrFromMaps(&MI);
|
|
MBB.erase(&MI);
|
|
Erased = true;
|
|
Spills.disallowClobberPhysReg(VirtReg);
|
|
goto ProcessNextInst;
|
|
}
|
|
|
|
// If it's not a no-op copy, it clobbers the value in the destreg.
|
|
Spills.ClobberPhysReg(VirtReg);
|
|
ReusedOperands.markClobbered(VirtReg);
|
|
|
|
// Check to see if this instruction is a load from a stack slot into
|
|
// a register. If so, this provides the stack slot value in the reg.
|
|
int FrameIdx;
|
|
if (unsigned DestReg = TII->isLoadFromStackSlot(&MI, FrameIdx)) {
|
|
assert(DestReg == VirtReg && "Unknown load situation!");
|
|
|
|
// If it is a folded reference, then it's not safe to clobber.
|
|
bool Folded = FoldedSS.count(FrameIdx);
|
|
// Otherwise, if it wasn't available, remember that it is now!
|
|
Spills.addAvailable(FrameIdx, DestReg, !Folded);
|
|
goto ProcessNextInst;
|
|
}
|
|
|
|
continue;
|
|
}
|
|
|
|
unsigned SubIdx = MO.getSubReg();
|
|
bool DoReMat = VRM.isReMaterialized(VirtReg);
|
|
if (DoReMat)
|
|
ReMatDefs.insert(&MI);
|
|
|
|
// The only vregs left are stack slot definitions.
|
|
int StackSlot = VRM.getStackSlot(VirtReg);
|
|
const TargetRegisterClass *RC = RegInfo->getRegClass(VirtReg);
|
|
|
|
// If this def is part of a two-address operand, make sure to execute
|
|
// the store from the correct physical register.
|
|
unsigned PhysReg;
|
|
unsigned TiedOp;
|
|
if (MI.isRegTiedToUseOperand(i, &TiedOp)) {
|
|
PhysReg = MI.getOperand(TiedOp).getReg();
|
|
if (SubIdx) {
|
|
unsigned SuperReg = findSuperReg(RC, PhysReg, SubIdx, TRI);
|
|
assert(SuperReg && TRI->getSubReg(SuperReg, SubIdx) == PhysReg &&
|
|
"Can't find corresponding super-register!");
|
|
PhysReg = SuperReg;
|
|
}
|
|
} else {
|
|
PhysReg = VRM.getPhys(VirtReg);
|
|
if (ReusedOperands.isClobbered(PhysReg)) {
|
|
// Another def has taken the assigned physreg. It must have been a
|
|
// use&def which got it due to reuse. Undo the reuse!
|
|
PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI,
|
|
Spills, MaybeDeadStores, RegKills, KillOps, VRM);
|
|
}
|
|
}
|
|
|
|
assert(PhysReg && "VR not assigned a physical register?");
|
|
RegInfo->setPhysRegUsed(PhysReg);
|
|
unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg;
|
|
ReusedOperands.markClobbered(RReg);
|
|
MI.getOperand(i).setReg(RReg);
|
|
MI.getOperand(i).setSubReg(0);
|
|
|
|
if (!MO.isDead()) {
|
|
MachineInstr *&LastStore = MaybeDeadStores[StackSlot];
|
|
SpillRegToStackSlot(MBB, MII, -1, PhysReg, StackSlot, RC, true,
|
|
LastStore, Spills, ReMatDefs, RegKills, KillOps, VRM);
|
|
NextMII = next(MII);
|
|
|
|
// Check to see if this is a noop copy. If so, eliminate the
|
|
// instruction before considering the dest reg to be changed.
|
|
{
|
|
unsigned Src, Dst, SrcSR, DstSR;
|
|
if (TII->isMoveInstr(MI, Src, Dst, SrcSR, DstSR) && Src == Dst) {
|
|
++NumDCE;
|
|
DOUT << "Removing now-noop copy: " << MI;
|
|
InvalidateKills(MI, RegKills, KillOps);
|
|
VRM.RemoveMachineInstrFromMaps(&MI);
|
|
MBB.erase(&MI);
|
|
Erased = true;
|
|
UpdateKills(*LastStore, RegKills, KillOps, TRI);
|
|
goto ProcessNextInst;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
ProcessNextInst:
|
|
DistanceMap.insert(std::make_pair(&MI, Dist++));
|
|
if (!Erased && !BackTracked) {
|
|
for (MachineBasicBlock::iterator II = &MI; II != NextMII; ++II)
|
|
UpdateKills(*II, RegKills, KillOps, TRI);
|
|
}
|
|
MII = NextMII;
|
|
}
|
|
|
|
}
|
|
|
|
llvm::Spiller* llvm::createSpiller() {
|
|
switch (SpillerOpt) {
|
|
default: assert(0 && "Unreachable!");
|
|
case local:
|
|
return new LocalSpiller();
|
|
case simple:
|
|
return new SimpleSpiller();
|
|
}
|
|
}
|