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cb6404711b
A live range cannot be split everywhere in a basic block. A split must go before the first terminator, and if the variable is live into a landing pad, the split must happen before the call that can throw. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124894 91177308-0d34-0410-b5e6-96231b3b80d8
2016 lines
74 KiB
C++
2016 lines
74 KiB
C++
//===-- LiveIntervalAnalysis.cpp - Live Interval Analysis -----------------===//
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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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//
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// This file implements the LiveInterval analysis pass which is used
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// by the Linear Scan Register allocator. This pass linearizes the
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// basic blocks of the function in DFS order and uses the
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// LiveVariables pass to conservatively compute live intervals for
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// each virtual and physical register.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "liveintervals"
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#include "llvm/CodeGen/LiveIntervalAnalysis.h"
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#include "VirtRegMap.h"
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#include "llvm/Value.h"
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/CodeGen/LiveVariables.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineInstr.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/MachineLoopInfo.h"
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#include "llvm/CodeGen/MachineMemOperand.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/CodeGen/ProcessImplicitDefs.h"
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#include "llvm/Target/TargetRegisterInfo.h"
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#include "llvm/Target/TargetInstrInfo.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/TargetOptions.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/ADT/DepthFirstIterator.h"
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#include "llvm/ADT/SmallSet.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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#include <limits>
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#include <cmath>
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using namespace llvm;
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// Hidden options for help debugging.
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static cl::opt<bool> DisableReMat("disable-rematerialization",
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cl::init(false), cl::Hidden);
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STATISTIC(numIntervals , "Number of original intervals");
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STATISTIC(numFolds , "Number of loads/stores folded into instructions");
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STATISTIC(numSplits , "Number of intervals split");
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char LiveIntervals::ID = 0;
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INITIALIZE_PASS_BEGIN(LiveIntervals, "liveintervals",
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"Live Interval Analysis", false, false)
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INITIALIZE_PASS_DEPENDENCY(LiveVariables)
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INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
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INITIALIZE_PASS_DEPENDENCY(PHIElimination)
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INITIALIZE_PASS_DEPENDENCY(TwoAddressInstructionPass)
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INITIALIZE_PASS_DEPENDENCY(ProcessImplicitDefs)
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INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
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INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
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INITIALIZE_PASS_END(LiveIntervals, "liveintervals",
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"Live Interval Analysis", false, false)
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void LiveIntervals::getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesCFG();
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AU.addRequired<AliasAnalysis>();
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AU.addPreserved<AliasAnalysis>();
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AU.addRequired<LiveVariables>();
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AU.addPreserved<LiveVariables>();
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AU.addRequired<MachineLoopInfo>();
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AU.addPreserved<MachineLoopInfo>();
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AU.addPreservedID(MachineDominatorsID);
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if (!StrongPHIElim) {
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AU.addPreservedID(PHIEliminationID);
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AU.addRequiredID(PHIEliminationID);
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}
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AU.addRequiredID(TwoAddressInstructionPassID);
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AU.addPreserved<ProcessImplicitDefs>();
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AU.addRequired<ProcessImplicitDefs>();
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AU.addPreserved<SlotIndexes>();
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AU.addRequiredTransitive<SlotIndexes>();
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MachineFunctionPass::getAnalysisUsage(AU);
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}
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void LiveIntervals::releaseMemory() {
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// Free the live intervals themselves.
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for (DenseMap<unsigned, LiveInterval*>::iterator I = r2iMap_.begin(),
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E = r2iMap_.end(); I != E; ++I)
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delete I->second;
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r2iMap_.clear();
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// Release VNInfo memory regions, VNInfo objects don't need to be dtor'd.
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VNInfoAllocator.Reset();
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while (!CloneMIs.empty()) {
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MachineInstr *MI = CloneMIs.back();
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CloneMIs.pop_back();
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mf_->DeleteMachineInstr(MI);
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}
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}
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/// runOnMachineFunction - Register allocate the whole function
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///
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bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {
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mf_ = &fn;
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mri_ = &mf_->getRegInfo();
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tm_ = &fn.getTarget();
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tri_ = tm_->getRegisterInfo();
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tii_ = tm_->getInstrInfo();
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aa_ = &getAnalysis<AliasAnalysis>();
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lv_ = &getAnalysis<LiveVariables>();
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indexes_ = &getAnalysis<SlotIndexes>();
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allocatableRegs_ = tri_->getAllocatableSet(fn);
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computeIntervals();
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numIntervals += getNumIntervals();
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DEBUG(dump());
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return true;
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}
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/// print - Implement the dump method.
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void LiveIntervals::print(raw_ostream &OS, const Module* ) const {
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OS << "********** INTERVALS **********\n";
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for (const_iterator I = begin(), E = end(); I != E; ++I) {
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I->second->print(OS, tri_);
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OS << "\n";
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}
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printInstrs(OS);
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}
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void LiveIntervals::printInstrs(raw_ostream &OS) const {
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OS << "********** MACHINEINSTRS **********\n";
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mf_->print(OS, indexes_);
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}
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void LiveIntervals::dumpInstrs() const {
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printInstrs(dbgs());
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}
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bool LiveIntervals::conflictsWithPhysReg(const LiveInterval &li,
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VirtRegMap &vrm, unsigned reg) {
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// We don't handle fancy stuff crossing basic block boundaries
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if (li.ranges.size() != 1)
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return true;
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const LiveRange &range = li.ranges.front();
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SlotIndex idx = range.start.getBaseIndex();
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SlotIndex end = range.end.getPrevSlot().getBaseIndex().getNextIndex();
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// Skip deleted instructions
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MachineInstr *firstMI = getInstructionFromIndex(idx);
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while (!firstMI && idx != end) {
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idx = idx.getNextIndex();
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firstMI = getInstructionFromIndex(idx);
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}
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if (!firstMI)
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return false;
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// Find last instruction in range
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SlotIndex lastIdx = end.getPrevIndex();
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MachineInstr *lastMI = getInstructionFromIndex(lastIdx);
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while (!lastMI && lastIdx != idx) {
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lastIdx = lastIdx.getPrevIndex();
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lastMI = getInstructionFromIndex(lastIdx);
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}
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if (!lastMI)
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return false;
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// Range cannot cross basic block boundaries or terminators
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MachineBasicBlock *MBB = firstMI->getParent();
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if (MBB != lastMI->getParent() || lastMI->getDesc().isTerminator())
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return true;
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MachineBasicBlock::const_iterator E = lastMI;
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++E;
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for (MachineBasicBlock::const_iterator I = firstMI; I != E; ++I) {
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const MachineInstr &MI = *I;
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// Allow copies to and from li.reg
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if (MI.isCopy())
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if (MI.getOperand(0).getReg() == li.reg ||
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MI.getOperand(1).getReg() == li.reg)
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continue;
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// Check for operands using reg
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for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
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const MachineOperand& mop = MI.getOperand(i);
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if (!mop.isReg())
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continue;
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unsigned PhysReg = mop.getReg();
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if (PhysReg == 0 || PhysReg == li.reg)
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continue;
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if (TargetRegisterInfo::isVirtualRegister(PhysReg)) {
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if (!vrm.hasPhys(PhysReg))
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continue;
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PhysReg = vrm.getPhys(PhysReg);
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}
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if (PhysReg && tri_->regsOverlap(PhysReg, reg))
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return true;
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}
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}
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// No conflicts found.
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return false;
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}
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bool LiveIntervals::conflictsWithAliasRef(LiveInterval &li, unsigned Reg,
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SmallPtrSet<MachineInstr*,32> &JoinedCopies) {
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for (LiveInterval::Ranges::const_iterator
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I = li.ranges.begin(), E = li.ranges.end(); I != E; ++I) {
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for (SlotIndex index = I->start.getBaseIndex(),
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end = I->end.getPrevSlot().getBaseIndex().getNextIndex();
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index != end;
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index = index.getNextIndex()) {
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MachineInstr *MI = getInstructionFromIndex(index);
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if (!MI)
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continue; // skip deleted instructions
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if (JoinedCopies.count(MI))
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continue;
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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())
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continue;
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unsigned PhysReg = MO.getReg();
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if (PhysReg == 0 || PhysReg == Reg ||
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TargetRegisterInfo::isVirtualRegister(PhysReg))
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continue;
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if (tri_->regsOverlap(Reg, PhysReg))
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return true;
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}
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}
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}
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return false;
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}
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static
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bool MultipleDefsBySameMI(const MachineInstr &MI, unsigned MOIdx) {
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unsigned Reg = MI.getOperand(MOIdx).getReg();
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for (unsigned i = MOIdx+1, e = MI.getNumOperands(); i < e; ++i) {
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const MachineOperand &MO = MI.getOperand(i);
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if (!MO.isReg())
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continue;
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if (MO.getReg() == Reg && MO.isDef()) {
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assert(MI.getOperand(MOIdx).getSubReg() != MO.getSubReg() &&
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MI.getOperand(MOIdx).getSubReg() &&
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(MO.getSubReg() || MO.isImplicit()));
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return true;
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}
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}
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return false;
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}
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/// isPartialRedef - Return true if the specified def at the specific index is
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/// partially re-defining the specified live interval. A common case of this is
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/// a definition of the sub-register.
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bool LiveIntervals::isPartialRedef(SlotIndex MIIdx, MachineOperand &MO,
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LiveInterval &interval) {
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if (!MO.getSubReg() || MO.isEarlyClobber())
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return false;
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SlotIndex RedefIndex = MIIdx.getDefIndex();
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const LiveRange *OldLR =
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interval.getLiveRangeContaining(RedefIndex.getUseIndex());
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MachineInstr *DefMI = getInstructionFromIndex(OldLR->valno->def);
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if (DefMI != 0) {
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return DefMI->findRegisterDefOperandIdx(interval.reg) != -1;
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}
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return false;
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}
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void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock *mbb,
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MachineBasicBlock::iterator mi,
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SlotIndex MIIdx,
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MachineOperand& MO,
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unsigned MOIdx,
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LiveInterval &interval) {
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DEBUG(dbgs() << "\t\tregister: " << PrintReg(interval.reg, tri_));
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// Virtual registers may be defined multiple times (due to phi
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// elimination and 2-addr elimination). Much of what we do only has to be
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// done once for the vreg. We use an empty interval to detect the first
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// time we see a vreg.
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LiveVariables::VarInfo& vi = lv_->getVarInfo(interval.reg);
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if (interval.empty()) {
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// Get the Idx of the defining instructions.
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SlotIndex defIndex = MIIdx.getDefIndex();
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// Earlyclobbers move back one, so that they overlap the live range
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// of inputs.
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if (MO.isEarlyClobber())
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defIndex = MIIdx.getUseIndex();
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// Make sure the first definition is not a partial redefinition. Add an
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// <imp-def> of the full register.
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if (MO.getSubReg())
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mi->addRegisterDefined(interval.reg);
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MachineInstr *CopyMI = NULL;
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if (mi->isCopyLike()) {
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CopyMI = mi;
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}
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VNInfo *ValNo = interval.getNextValue(defIndex, CopyMI, VNInfoAllocator);
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assert(ValNo->id == 0 && "First value in interval is not 0?");
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// Loop over all of the blocks that the vreg is defined in. There are
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// two cases we have to handle here. The most common case is a vreg
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// whose lifetime is contained within a basic block. In this case there
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// will be a single kill, in MBB, which comes after the definition.
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if (vi.Kills.size() == 1 && vi.Kills[0]->getParent() == mbb) {
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// FIXME: what about dead vars?
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SlotIndex killIdx;
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if (vi.Kills[0] != mi)
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killIdx = getInstructionIndex(vi.Kills[0]).getDefIndex();
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else
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killIdx = defIndex.getStoreIndex();
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// If the kill happens after the definition, we have an intra-block
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// live range.
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if (killIdx > defIndex) {
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assert(vi.AliveBlocks.empty() &&
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"Shouldn't be alive across any blocks!");
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LiveRange LR(defIndex, killIdx, ValNo);
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interval.addRange(LR);
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DEBUG(dbgs() << " +" << LR << "\n");
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return;
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}
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}
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// The other case we handle is when a virtual register lives to the end
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// of the defining block, potentially live across some blocks, then is
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// live into some number of blocks, but gets killed. Start by adding a
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// range that goes from this definition to the end of the defining block.
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LiveRange NewLR(defIndex, getMBBEndIdx(mbb), ValNo);
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DEBUG(dbgs() << " +" << NewLR);
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interval.addRange(NewLR);
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bool PHIJoin = lv_->isPHIJoin(interval.reg);
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if (PHIJoin) {
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// A phi join register is killed at the end of the MBB and revived as a new
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// valno in the killing blocks.
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assert(vi.AliveBlocks.empty() && "Phi join can't pass through blocks");
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DEBUG(dbgs() << " phi-join");
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ValNo->setHasPHIKill(true);
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} else {
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// Iterate over all of the blocks that the variable is completely
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// live in, adding [insrtIndex(begin), instrIndex(end)+4) to the
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// live interval.
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for (SparseBitVector<>::iterator I = vi.AliveBlocks.begin(),
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E = vi.AliveBlocks.end(); I != E; ++I) {
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MachineBasicBlock *aliveBlock = mf_->getBlockNumbered(*I);
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LiveRange LR(getMBBStartIdx(aliveBlock), getMBBEndIdx(aliveBlock), ValNo);
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interval.addRange(LR);
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DEBUG(dbgs() << " +" << LR);
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}
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}
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// Finally, this virtual register is live from the start of any killing
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// block to the 'use' slot of the killing instruction.
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for (unsigned i = 0, e = vi.Kills.size(); i != e; ++i) {
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MachineInstr *Kill = vi.Kills[i];
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SlotIndex Start = getMBBStartIdx(Kill->getParent());
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SlotIndex killIdx = getInstructionIndex(Kill).getDefIndex();
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// Create interval with one of a NEW value number. Note that this value
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// number isn't actually defined by an instruction, weird huh? :)
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if (PHIJoin) {
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assert(getInstructionFromIndex(Start) == 0 &&
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"PHI def index points at actual instruction.");
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ValNo = interval.getNextValue(Start, 0, VNInfoAllocator);
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ValNo->setIsPHIDef(true);
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}
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LiveRange LR(Start, killIdx, ValNo);
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interval.addRange(LR);
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DEBUG(dbgs() << " +" << LR);
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}
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} else {
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if (MultipleDefsBySameMI(*mi, MOIdx))
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// Multiple defs of the same virtual register by the same instruction.
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// e.g. %reg1031:5<def>, %reg1031:6<def> = VLD1q16 %reg1024<kill>, ...
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// This is likely due to elimination of REG_SEQUENCE instructions. Return
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// here since there is nothing to do.
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return;
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// If this is the second time we see a virtual register definition, it
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// must be due to phi elimination or two addr elimination. If this is
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// the result of two address elimination, then the vreg is one of the
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// def-and-use register operand.
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// It may also be partial redef like this:
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// 80 %reg1041:6<def> = VSHRNv4i16 %reg1034<kill>, 12, pred:14, pred:%reg0
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// 120 %reg1041:5<def> = VSHRNv4i16 %reg1039<kill>, 12, pred:14, pred:%reg0
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bool PartReDef = isPartialRedef(MIIdx, MO, interval);
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if (PartReDef || mi->isRegTiedToUseOperand(MOIdx)) {
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// If this is a two-address definition, then we have already processed
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// the live range. The only problem is that we didn't realize there
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// are actually two values in the live interval. Because of this we
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// need to take the LiveRegion that defines this register and split it
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// into two values.
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SlotIndex RedefIndex = MIIdx.getDefIndex();
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if (MO.isEarlyClobber())
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RedefIndex = MIIdx.getUseIndex();
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const LiveRange *OldLR =
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interval.getLiveRangeContaining(RedefIndex.getUseIndex());
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VNInfo *OldValNo = OldLR->valno;
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SlotIndex DefIndex = OldValNo->def.getDefIndex();
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// Delete the previous value, which should be short and continuous,
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// because the 2-addr copy must be in the same MBB as the redef.
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interval.removeRange(DefIndex, RedefIndex);
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// The new value number (#1) is defined by the instruction we claimed
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// defined value #0.
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VNInfo *ValNo = interval.createValueCopy(OldValNo, VNInfoAllocator);
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// Value#0 is now defined by the 2-addr instruction.
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OldValNo->def = RedefIndex;
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OldValNo->setCopy(0);
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// A re-def may be a copy. e.g. %reg1030:6<def> = VMOVD %reg1026, ...
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if (PartReDef && mi->isCopyLike())
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OldValNo->setCopy(&*mi);
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// Add the new live interval which replaces the range for the input copy.
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LiveRange LR(DefIndex, RedefIndex, ValNo);
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DEBUG(dbgs() << " replace range with " << LR);
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interval.addRange(LR);
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// If this redefinition is dead, we need to add a dummy unit live
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// range covering the def slot.
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if (MO.isDead())
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interval.addRange(LiveRange(RedefIndex, RedefIndex.getStoreIndex(),
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OldValNo));
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DEBUG({
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dbgs() << " RESULT: ";
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interval.print(dbgs(), tri_);
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});
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} else if (lv_->isPHIJoin(interval.reg)) {
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// In the case of PHI elimination, each variable definition is only
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// live until the end of the block. We've already taken care of the
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// rest of the live range.
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SlotIndex defIndex = MIIdx.getDefIndex();
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if (MO.isEarlyClobber())
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defIndex = MIIdx.getUseIndex();
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VNInfo *ValNo;
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MachineInstr *CopyMI = NULL;
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|
if (mi->isCopyLike())
|
|
CopyMI = mi;
|
|
ValNo = interval.getNextValue(defIndex, CopyMI, VNInfoAllocator);
|
|
|
|
SlotIndex killIndex = getMBBEndIdx(mbb);
|
|
LiveRange LR(defIndex, killIndex, ValNo);
|
|
interval.addRange(LR);
|
|
ValNo->setHasPHIKill(true);
|
|
DEBUG(dbgs() << " phi-join +" << LR);
|
|
} else {
|
|
llvm_unreachable("Multiply defined register");
|
|
}
|
|
}
|
|
|
|
DEBUG(dbgs() << '\n');
|
|
}
|
|
|
|
void LiveIntervals::handlePhysicalRegisterDef(MachineBasicBlock *MBB,
|
|
MachineBasicBlock::iterator mi,
|
|
SlotIndex MIIdx,
|
|
MachineOperand& MO,
|
|
LiveInterval &interval,
|
|
MachineInstr *CopyMI) {
|
|
// A physical register cannot be live across basic block, so its
|
|
// lifetime must end somewhere in its defining basic block.
|
|
DEBUG(dbgs() << "\t\tregister: " << PrintReg(interval.reg, tri_));
|
|
|
|
SlotIndex baseIndex = MIIdx;
|
|
SlotIndex start = baseIndex.getDefIndex();
|
|
// Earlyclobbers move back one.
|
|
if (MO.isEarlyClobber())
|
|
start = MIIdx.getUseIndex();
|
|
SlotIndex end = start;
|
|
|
|
// If it is not used after definition, it is considered dead at
|
|
// the instruction defining it. Hence its interval is:
|
|
// [defSlot(def), defSlot(def)+1)
|
|
// For earlyclobbers, the defSlot was pushed back one; the extra
|
|
// advance below compensates.
|
|
if (MO.isDead()) {
|
|
DEBUG(dbgs() << " dead");
|
|
end = start.getStoreIndex();
|
|
goto exit;
|
|
}
|
|
|
|
// If it is not dead on definition, it must be killed by a
|
|
// subsequent instruction. Hence its interval is:
|
|
// [defSlot(def), useSlot(kill)+1)
|
|
baseIndex = baseIndex.getNextIndex();
|
|
while (++mi != MBB->end()) {
|
|
|
|
if (mi->isDebugValue())
|
|
continue;
|
|
if (getInstructionFromIndex(baseIndex) == 0)
|
|
baseIndex = indexes_->getNextNonNullIndex(baseIndex);
|
|
|
|
if (mi->killsRegister(interval.reg, tri_)) {
|
|
DEBUG(dbgs() << " killed");
|
|
end = baseIndex.getDefIndex();
|
|
goto exit;
|
|
} else {
|
|
int DefIdx = mi->findRegisterDefOperandIdx(interval.reg,false,false,tri_);
|
|
if (DefIdx != -1) {
|
|
if (mi->isRegTiedToUseOperand(DefIdx)) {
|
|
// Two-address instruction.
|
|
end = baseIndex.getDefIndex();
|
|
} else {
|
|
// Another instruction redefines the register before it is ever read.
|
|
// Then the register is essentially dead at the instruction that
|
|
// defines it. Hence its interval is:
|
|
// [defSlot(def), defSlot(def)+1)
|
|
DEBUG(dbgs() << " dead");
|
|
end = start.getStoreIndex();
|
|
}
|
|
goto exit;
|
|
}
|
|
}
|
|
|
|
baseIndex = baseIndex.getNextIndex();
|
|
}
|
|
|
|
// The only case we should have a dead physreg here without a killing or
|
|
// instruction where we know it's dead is if it is live-in to the function
|
|
// and never used. Another possible case is the implicit use of the
|
|
// physical register has been deleted by two-address pass.
|
|
end = start.getStoreIndex();
|
|
|
|
exit:
|
|
assert(start < end && "did not find end of interval?");
|
|
|
|
// Already exists? Extend old live interval.
|
|
VNInfo *ValNo = interval.getVNInfoAt(start);
|
|
bool Extend = ValNo != 0;
|
|
if (!Extend)
|
|
ValNo = interval.getNextValue(start, CopyMI, VNInfoAllocator);
|
|
if (Extend && MO.isEarlyClobber())
|
|
ValNo->setHasRedefByEC(true);
|
|
LiveRange LR(start, end, ValNo);
|
|
interval.addRange(LR);
|
|
DEBUG(dbgs() << " +" << LR << '\n');
|
|
}
|
|
|
|
void LiveIntervals::handleRegisterDef(MachineBasicBlock *MBB,
|
|
MachineBasicBlock::iterator MI,
|
|
SlotIndex MIIdx,
|
|
MachineOperand& MO,
|
|
unsigned MOIdx) {
|
|
if (TargetRegisterInfo::isVirtualRegister(MO.getReg()))
|
|
handleVirtualRegisterDef(MBB, MI, MIIdx, MO, MOIdx,
|
|
getOrCreateInterval(MO.getReg()));
|
|
else if (allocatableRegs_[MO.getReg()]) {
|
|
MachineInstr *CopyMI = NULL;
|
|
if (MI->isCopyLike())
|
|
CopyMI = MI;
|
|
handlePhysicalRegisterDef(MBB, MI, MIIdx, MO,
|
|
getOrCreateInterval(MO.getReg()), CopyMI);
|
|
// Def of a register also defines its sub-registers.
|
|
for (const unsigned* AS = tri_->getSubRegisters(MO.getReg()); *AS; ++AS)
|
|
// If MI also modifies the sub-register explicitly, avoid processing it
|
|
// more than once. Do not pass in TRI here so it checks for exact match.
|
|
if (!MI->definesRegister(*AS))
|
|
handlePhysicalRegisterDef(MBB, MI, MIIdx, MO,
|
|
getOrCreateInterval(*AS), 0);
|
|
}
|
|
}
|
|
|
|
void LiveIntervals::handleLiveInRegister(MachineBasicBlock *MBB,
|
|
SlotIndex MIIdx,
|
|
LiveInterval &interval, bool isAlias) {
|
|
DEBUG(dbgs() << "\t\tlivein register: " << PrintReg(interval.reg, tri_));
|
|
|
|
// Look for kills, if it reaches a def before it's killed, then it shouldn't
|
|
// be considered a livein.
|
|
MachineBasicBlock::iterator mi = MBB->begin();
|
|
MachineBasicBlock::iterator E = MBB->end();
|
|
// Skip over DBG_VALUE at the start of the MBB.
|
|
if (mi != E && mi->isDebugValue()) {
|
|
while (++mi != E && mi->isDebugValue())
|
|
;
|
|
if (mi == E)
|
|
// MBB is empty except for DBG_VALUE's.
|
|
return;
|
|
}
|
|
|
|
SlotIndex baseIndex = MIIdx;
|
|
SlotIndex start = baseIndex;
|
|
if (getInstructionFromIndex(baseIndex) == 0)
|
|
baseIndex = indexes_->getNextNonNullIndex(baseIndex);
|
|
|
|
SlotIndex end = baseIndex;
|
|
bool SeenDefUse = false;
|
|
|
|
while (mi != E) {
|
|
if (mi->killsRegister(interval.reg, tri_)) {
|
|
DEBUG(dbgs() << " killed");
|
|
end = baseIndex.getDefIndex();
|
|
SeenDefUse = true;
|
|
break;
|
|
} else if (mi->definesRegister(interval.reg, tri_)) {
|
|
// Another instruction redefines the register before it is ever read.
|
|
// Then the register is essentially dead at the instruction that defines
|
|
// it. Hence its interval is:
|
|
// [defSlot(def), defSlot(def)+1)
|
|
DEBUG(dbgs() << " dead");
|
|
end = start.getStoreIndex();
|
|
SeenDefUse = true;
|
|
break;
|
|
}
|
|
|
|
while (++mi != E && mi->isDebugValue())
|
|
// Skip over DBG_VALUE.
|
|
;
|
|
if (mi != E)
|
|
baseIndex = indexes_->getNextNonNullIndex(baseIndex);
|
|
}
|
|
|
|
// Live-in register might not be used at all.
|
|
if (!SeenDefUse) {
|
|
if (isAlias) {
|
|
DEBUG(dbgs() << " dead");
|
|
end = MIIdx.getStoreIndex();
|
|
} else {
|
|
DEBUG(dbgs() << " live through");
|
|
end = baseIndex;
|
|
}
|
|
}
|
|
|
|
SlotIndex defIdx = getMBBStartIdx(MBB);
|
|
assert(getInstructionFromIndex(defIdx) == 0 &&
|
|
"PHI def index points at actual instruction.");
|
|
VNInfo *vni =
|
|
interval.getNextValue(defIdx, 0, VNInfoAllocator);
|
|
vni->setIsPHIDef(true);
|
|
LiveRange LR(start, end, vni);
|
|
|
|
interval.addRange(LR);
|
|
DEBUG(dbgs() << " +" << LR << '\n');
|
|
}
|
|
|
|
/// computeIntervals - computes the live intervals for virtual
|
|
/// registers. for some ordering of the machine instructions [1,N] a
|
|
/// live interval is an interval [i, j) where 1 <= i <= j < N for
|
|
/// which a variable is live
|
|
void LiveIntervals::computeIntervals() {
|
|
DEBUG(dbgs() << "********** COMPUTING LIVE INTERVALS **********\n"
|
|
<< "********** Function: "
|
|
<< ((Value*)mf_->getFunction())->getName() << '\n');
|
|
|
|
SmallVector<unsigned, 8> UndefUses;
|
|
for (MachineFunction::iterator MBBI = mf_->begin(), E = mf_->end();
|
|
MBBI != E; ++MBBI) {
|
|
MachineBasicBlock *MBB = MBBI;
|
|
if (MBB->empty())
|
|
continue;
|
|
|
|
// Track the index of the current machine instr.
|
|
SlotIndex MIIndex = getMBBStartIdx(MBB);
|
|
DEBUG(dbgs() << "BB#" << MBB->getNumber()
|
|
<< ":\t\t# derived from " << MBB->getName() << "\n");
|
|
|
|
// Create intervals for live-ins to this BB first.
|
|
for (MachineBasicBlock::livein_iterator LI = MBB->livein_begin(),
|
|
LE = MBB->livein_end(); LI != LE; ++LI) {
|
|
handleLiveInRegister(MBB, MIIndex, getOrCreateInterval(*LI));
|
|
// Multiple live-ins can alias the same register.
|
|
for (const unsigned* AS = tri_->getSubRegisters(*LI); *AS; ++AS)
|
|
if (!hasInterval(*AS))
|
|
handleLiveInRegister(MBB, MIIndex, getOrCreateInterval(*AS),
|
|
true);
|
|
}
|
|
|
|
// Skip over empty initial indices.
|
|
if (getInstructionFromIndex(MIIndex) == 0)
|
|
MIIndex = indexes_->getNextNonNullIndex(MIIndex);
|
|
|
|
for (MachineBasicBlock::iterator MI = MBB->begin(), miEnd = MBB->end();
|
|
MI != miEnd; ++MI) {
|
|
DEBUG(dbgs() << MIIndex << "\t" << *MI);
|
|
if (MI->isDebugValue())
|
|
continue;
|
|
|
|
// Handle defs.
|
|
for (int i = MI->getNumOperands() - 1; i >= 0; --i) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
if (!MO.isReg() || !MO.getReg())
|
|
continue;
|
|
|
|
// handle register defs - build intervals
|
|
if (MO.isDef())
|
|
handleRegisterDef(MBB, MI, MIIndex, MO, i);
|
|
else if (MO.isUndef())
|
|
UndefUses.push_back(MO.getReg());
|
|
}
|
|
|
|
// Move to the next instr slot.
|
|
MIIndex = indexes_->getNextNonNullIndex(MIIndex);
|
|
}
|
|
}
|
|
|
|
// Create empty intervals for registers defined by implicit_def's (except
|
|
// for those implicit_def that define values which are liveout of their
|
|
// blocks.
|
|
for (unsigned i = 0, e = UndefUses.size(); i != e; ++i) {
|
|
unsigned UndefReg = UndefUses[i];
|
|
(void)getOrCreateInterval(UndefReg);
|
|
}
|
|
}
|
|
|
|
LiveInterval* LiveIntervals::createInterval(unsigned reg) {
|
|
float Weight = TargetRegisterInfo::isPhysicalRegister(reg) ? HUGE_VALF : 0.0F;
|
|
return new LiveInterval(reg, Weight);
|
|
}
|
|
|
|
/// dupInterval - Duplicate a live interval. The caller is responsible for
|
|
/// managing the allocated memory.
|
|
LiveInterval* LiveIntervals::dupInterval(LiveInterval *li) {
|
|
LiveInterval *NewLI = createInterval(li->reg);
|
|
NewLI->Copy(*li, mri_, getVNInfoAllocator());
|
|
return NewLI;
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Register allocator hooks.
|
|
//
|
|
|
|
MachineBasicBlock::iterator
|
|
LiveIntervals::getLastSplitPoint(const LiveInterval &li,
|
|
MachineBasicBlock *mbb) {
|
|
const MachineBasicBlock *lpad = mbb->getLandingPadSuccessor();
|
|
|
|
// If li is not live into a landing pad, we can insert spill code before the
|
|
// first terminator.
|
|
if (!lpad || !isLiveInToMBB(li, lpad))
|
|
return mbb->getFirstTerminator();
|
|
|
|
// When there is a landing pad, spill code must go before the call instruction
|
|
// that can throw.
|
|
MachineBasicBlock::iterator I = mbb->end(), B = mbb->begin();
|
|
while (I != B) {
|
|
--I;
|
|
if (I->getDesc().isCall())
|
|
return I;
|
|
}
|
|
assert(0 && "Block with landing pad successor contains no call instruction");
|
|
return mbb->getFirstTerminator();
|
|
}
|
|
|
|
/// getReMatImplicitUse - If the remat definition MI has one (for now, we only
|
|
/// allow one) virtual register operand, then its uses are implicitly using
|
|
/// the register. Returns the virtual register.
|
|
unsigned LiveIntervals::getReMatImplicitUse(const LiveInterval &li,
|
|
MachineInstr *MI) const {
|
|
unsigned RegOp = 0;
|
|
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
if (!MO.isReg() || !MO.isUse())
|
|
continue;
|
|
unsigned Reg = MO.getReg();
|
|
if (Reg == 0 || Reg == li.reg)
|
|
continue;
|
|
|
|
if (TargetRegisterInfo::isPhysicalRegister(Reg) &&
|
|
!allocatableRegs_[Reg])
|
|
continue;
|
|
// FIXME: For now, only remat MI with at most one register operand.
|
|
assert(!RegOp &&
|
|
"Can't rematerialize instruction with multiple register operand!");
|
|
RegOp = MO.getReg();
|
|
#ifndef NDEBUG
|
|
break;
|
|
#endif
|
|
}
|
|
return RegOp;
|
|
}
|
|
|
|
/// isValNoAvailableAt - Return true if the val# of the specified interval
|
|
/// which reaches the given instruction also reaches the specified use index.
|
|
bool LiveIntervals::isValNoAvailableAt(const LiveInterval &li, MachineInstr *MI,
|
|
SlotIndex UseIdx) const {
|
|
VNInfo *UValNo = li.getVNInfoAt(UseIdx);
|
|
return UValNo && UValNo == li.getVNInfoAt(getInstructionIndex(MI));
|
|
}
|
|
|
|
/// isReMaterializable - Returns true if the definition MI of the specified
|
|
/// val# of the specified interval is re-materializable.
|
|
bool
|
|
LiveIntervals::isReMaterializable(const LiveInterval &li,
|
|
const VNInfo *ValNo, MachineInstr *MI,
|
|
const SmallVectorImpl<LiveInterval*> &SpillIs,
|
|
bool &isLoad) {
|
|
if (DisableReMat)
|
|
return false;
|
|
|
|
if (!tii_->isTriviallyReMaterializable(MI, aa_))
|
|
return false;
|
|
|
|
// Target-specific code can mark an instruction as being rematerializable
|
|
// if it has one virtual reg use, though it had better be something like
|
|
// a PIC base register which is likely to be live everywhere.
|
|
unsigned ImpUse = getReMatImplicitUse(li, MI);
|
|
if (ImpUse) {
|
|
const LiveInterval &ImpLi = getInterval(ImpUse);
|
|
for (MachineRegisterInfo::use_nodbg_iterator
|
|
ri = mri_->use_nodbg_begin(li.reg), re = mri_->use_nodbg_end();
|
|
ri != re; ++ri) {
|
|
MachineInstr *UseMI = &*ri;
|
|
SlotIndex UseIdx = getInstructionIndex(UseMI);
|
|
if (li.getVNInfoAt(UseIdx) != ValNo)
|
|
continue;
|
|
if (!isValNoAvailableAt(ImpLi, MI, UseIdx))
|
|
return false;
|
|
}
|
|
|
|
// If a register operand of the re-materialized instruction is going to
|
|
// be spilled next, then it's not legal to re-materialize this instruction.
|
|
for (unsigned i = 0, e = SpillIs.size(); i != e; ++i)
|
|
if (ImpUse == SpillIs[i]->reg)
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// isReMaterializable - Returns true if the definition MI of the specified
|
|
/// val# of the specified interval is re-materializable.
|
|
bool LiveIntervals::isReMaterializable(const LiveInterval &li,
|
|
const VNInfo *ValNo, MachineInstr *MI) {
|
|
SmallVector<LiveInterval*, 4> Dummy1;
|
|
bool Dummy2;
|
|
return isReMaterializable(li, ValNo, MI, Dummy1, Dummy2);
|
|
}
|
|
|
|
/// isReMaterializable - Returns true if every definition of MI of every
|
|
/// val# of the specified interval is re-materializable.
|
|
bool
|
|
LiveIntervals::isReMaterializable(const LiveInterval &li,
|
|
const SmallVectorImpl<LiveInterval*> &SpillIs,
|
|
bool &isLoad) {
|
|
isLoad = false;
|
|
for (LiveInterval::const_vni_iterator i = li.vni_begin(), e = li.vni_end();
|
|
i != e; ++i) {
|
|
const VNInfo *VNI = *i;
|
|
if (VNI->isUnused())
|
|
continue; // Dead val#.
|
|
// Is the def for the val# rematerializable?
|
|
MachineInstr *ReMatDefMI = getInstructionFromIndex(VNI->def);
|
|
if (!ReMatDefMI)
|
|
return false;
|
|
bool DefIsLoad = false;
|
|
if (!ReMatDefMI ||
|
|
!isReMaterializable(li, VNI, ReMatDefMI, SpillIs, DefIsLoad))
|
|
return false;
|
|
isLoad |= DefIsLoad;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// FilterFoldedOps - Filter out two-address use operands. Return
|
|
/// true if it finds any issue with the operands that ought to prevent
|
|
/// folding.
|
|
static bool FilterFoldedOps(MachineInstr *MI,
|
|
SmallVector<unsigned, 2> &Ops,
|
|
unsigned &MRInfo,
|
|
SmallVector<unsigned, 2> &FoldOps) {
|
|
MRInfo = 0;
|
|
for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
|
|
unsigned OpIdx = Ops[i];
|
|
MachineOperand &MO = MI->getOperand(OpIdx);
|
|
// FIXME: fold subreg use.
|
|
if (MO.getSubReg())
|
|
return true;
|
|
if (MO.isDef())
|
|
MRInfo |= (unsigned)VirtRegMap::isMod;
|
|
else {
|
|
// Filter out two-address use operand(s).
|
|
if (MI->isRegTiedToDefOperand(OpIdx)) {
|
|
MRInfo = VirtRegMap::isModRef;
|
|
continue;
|
|
}
|
|
MRInfo |= (unsigned)VirtRegMap::isRef;
|
|
}
|
|
FoldOps.push_back(OpIdx);
|
|
}
|
|
return false;
|
|
}
|
|
|
|
|
|
/// tryFoldMemoryOperand - Attempts to fold either a spill / restore from
|
|
/// slot / to reg or any rematerialized load into ith operand of specified
|
|
/// MI. If it is successul, MI is updated with the newly created MI and
|
|
/// returns true.
|
|
bool LiveIntervals::tryFoldMemoryOperand(MachineInstr* &MI,
|
|
VirtRegMap &vrm, MachineInstr *DefMI,
|
|
SlotIndex InstrIdx,
|
|
SmallVector<unsigned, 2> &Ops,
|
|
bool isSS, int Slot, unsigned Reg) {
|
|
// If it is an implicit def instruction, just delete it.
|
|
if (MI->isImplicitDef()) {
|
|
RemoveMachineInstrFromMaps(MI);
|
|
vrm.RemoveMachineInstrFromMaps(MI);
|
|
MI->eraseFromParent();
|
|
++numFolds;
|
|
return true;
|
|
}
|
|
|
|
// Filter the list of operand indexes that are to be folded. Abort if
|
|
// any operand will prevent folding.
|
|
unsigned MRInfo = 0;
|
|
SmallVector<unsigned, 2> FoldOps;
|
|
if (FilterFoldedOps(MI, Ops, MRInfo, FoldOps))
|
|
return false;
|
|
|
|
// The only time it's safe to fold into a two address instruction is when
|
|
// it's folding reload and spill from / into a spill stack slot.
|
|
if (DefMI && (MRInfo & VirtRegMap::isMod))
|
|
return false;
|
|
|
|
MachineInstr *fmi = isSS ? tii_->foldMemoryOperand(MI, FoldOps, Slot)
|
|
: tii_->foldMemoryOperand(MI, FoldOps, DefMI);
|
|
if (fmi) {
|
|
// Remember this instruction uses the spill slot.
|
|
if (isSS) vrm.addSpillSlotUse(Slot, fmi);
|
|
|
|
// Attempt to fold the memory reference into the instruction. If
|
|
// we can do this, we don't need to insert spill code.
|
|
if (isSS && !mf_->getFrameInfo()->isImmutableObjectIndex(Slot))
|
|
vrm.virtFolded(Reg, MI, fmi, (VirtRegMap::ModRef)MRInfo);
|
|
vrm.transferSpillPts(MI, fmi);
|
|
vrm.transferRestorePts(MI, fmi);
|
|
vrm.transferEmergencySpills(MI, fmi);
|
|
ReplaceMachineInstrInMaps(MI, fmi);
|
|
MI->eraseFromParent();
|
|
MI = fmi;
|
|
++numFolds;
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// canFoldMemoryOperand - Returns true if the specified load / store
|
|
/// folding is possible.
|
|
bool LiveIntervals::canFoldMemoryOperand(MachineInstr *MI,
|
|
SmallVector<unsigned, 2> &Ops,
|
|
bool ReMat) const {
|
|
// Filter the list of operand indexes that are to be folded. Abort if
|
|
// any operand will prevent folding.
|
|
unsigned MRInfo = 0;
|
|
SmallVector<unsigned, 2> FoldOps;
|
|
if (FilterFoldedOps(MI, Ops, MRInfo, FoldOps))
|
|
return false;
|
|
|
|
// It's only legal to remat for a use, not a def.
|
|
if (ReMat && (MRInfo & VirtRegMap::isMod))
|
|
return false;
|
|
|
|
return tii_->canFoldMemoryOperand(MI, FoldOps);
|
|
}
|
|
|
|
bool LiveIntervals::intervalIsInOneMBB(const LiveInterval &li) const {
|
|
LiveInterval::Ranges::const_iterator itr = li.ranges.begin();
|
|
|
|
MachineBasicBlock *mbb = indexes_->getMBBCoveringRange(itr->start, itr->end);
|
|
|
|
if (mbb == 0)
|
|
return false;
|
|
|
|
for (++itr; itr != li.ranges.end(); ++itr) {
|
|
MachineBasicBlock *mbb2 =
|
|
indexes_->getMBBCoveringRange(itr->start, itr->end);
|
|
|
|
if (mbb2 != mbb)
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/// rewriteImplicitOps - Rewrite implicit use operands of MI (i.e. uses of
|
|
/// interval on to-be re-materialized operands of MI) with new register.
|
|
void LiveIntervals::rewriteImplicitOps(const LiveInterval &li,
|
|
MachineInstr *MI, unsigned NewVReg,
|
|
VirtRegMap &vrm) {
|
|
// There is an implicit use. That means one of the other operand is
|
|
// being remat'ed and the remat'ed instruction has li.reg as an
|
|
// use operand. Make sure we rewrite that as well.
|
|
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
if (!MO.isReg())
|
|
continue;
|
|
unsigned Reg = MO.getReg();
|
|
if (!TargetRegisterInfo::isVirtualRegister(Reg))
|
|
continue;
|
|
if (!vrm.isReMaterialized(Reg))
|
|
continue;
|
|
MachineInstr *ReMatMI = vrm.getReMaterializedMI(Reg);
|
|
MachineOperand *UseMO = ReMatMI->findRegisterUseOperand(li.reg);
|
|
if (UseMO)
|
|
UseMO->setReg(NewVReg);
|
|
}
|
|
}
|
|
|
|
/// rewriteInstructionForSpills, rewriteInstructionsForSpills - Helper functions
|
|
/// for addIntervalsForSpills to rewrite uses / defs for the given live range.
|
|
bool LiveIntervals::
|
|
rewriteInstructionForSpills(const LiveInterval &li, const VNInfo *VNI,
|
|
bool TrySplit, SlotIndex index, SlotIndex end,
|
|
MachineInstr *MI,
|
|
MachineInstr *ReMatOrigDefMI, MachineInstr *ReMatDefMI,
|
|
unsigned Slot, int LdSlot,
|
|
bool isLoad, bool isLoadSS, bool DefIsReMat, bool CanDelete,
|
|
VirtRegMap &vrm,
|
|
const TargetRegisterClass* rc,
|
|
SmallVector<int, 4> &ReMatIds,
|
|
const MachineLoopInfo *loopInfo,
|
|
unsigned &NewVReg, unsigned ImpUse, bool &HasDef, bool &HasUse,
|
|
DenseMap<unsigned,unsigned> &MBBVRegsMap,
|
|
std::vector<LiveInterval*> &NewLIs) {
|
|
bool CanFold = false;
|
|
RestartInstruction:
|
|
for (unsigned i = 0; i != MI->getNumOperands(); ++i) {
|
|
MachineOperand& mop = MI->getOperand(i);
|
|
if (!mop.isReg())
|
|
continue;
|
|
unsigned Reg = mop.getReg();
|
|
if (!TargetRegisterInfo::isVirtualRegister(Reg))
|
|
continue;
|
|
if (Reg != li.reg)
|
|
continue;
|
|
|
|
bool TryFold = !DefIsReMat;
|
|
bool FoldSS = true; // Default behavior unless it's a remat.
|
|
int FoldSlot = Slot;
|
|
if (DefIsReMat) {
|
|
// If this is the rematerializable definition MI itself and
|
|
// all of its uses are rematerialized, simply delete it.
|
|
if (MI == ReMatOrigDefMI && CanDelete) {
|
|
DEBUG(dbgs() << "\t\t\t\tErasing re-materializable def: "
|
|
<< *MI << '\n');
|
|
RemoveMachineInstrFromMaps(MI);
|
|
vrm.RemoveMachineInstrFromMaps(MI);
|
|
MI->eraseFromParent();
|
|
break;
|
|
}
|
|
|
|
// If def for this use can't be rematerialized, then try folding.
|
|
// If def is rematerializable and it's a load, also try folding.
|
|
TryFold = !ReMatDefMI || (ReMatDefMI && (MI == ReMatOrigDefMI || isLoad));
|
|
if (isLoad) {
|
|
// Try fold loads (from stack slot, constant pool, etc.) into uses.
|
|
FoldSS = isLoadSS;
|
|
FoldSlot = LdSlot;
|
|
}
|
|
}
|
|
|
|
// Scan all of the operands of this instruction rewriting operands
|
|
// to use NewVReg instead of li.reg as appropriate. We do this for
|
|
// two reasons:
|
|
//
|
|
// 1. If the instr reads the same spilled vreg multiple times, we
|
|
// want to reuse the NewVReg.
|
|
// 2. If the instr is a two-addr instruction, we are required to
|
|
// keep the src/dst regs pinned.
|
|
//
|
|
// Keep track of whether we replace a use and/or def so that we can
|
|
// create the spill interval with the appropriate range.
|
|
SmallVector<unsigned, 2> Ops;
|
|
tie(HasUse, HasDef) = MI->readsWritesVirtualRegister(Reg, &Ops);
|
|
|
|
// Create a new virtual register for the spill interval.
|
|
// Create the new register now so we can map the fold instruction
|
|
// to the new register so when it is unfolded we get the correct
|
|
// answer.
|
|
bool CreatedNewVReg = false;
|
|
if (NewVReg == 0) {
|
|
NewVReg = mri_->createVirtualRegister(rc);
|
|
vrm.grow();
|
|
CreatedNewVReg = true;
|
|
|
|
// The new virtual register should get the same allocation hints as the
|
|
// old one.
|
|
std::pair<unsigned, unsigned> Hint = mri_->getRegAllocationHint(Reg);
|
|
if (Hint.first || Hint.second)
|
|
mri_->setRegAllocationHint(NewVReg, Hint.first, Hint.second);
|
|
}
|
|
|
|
if (!TryFold)
|
|
CanFold = false;
|
|
else {
|
|
// Do not fold load / store here if we are splitting. We'll find an
|
|
// optimal point to insert a load / store later.
|
|
if (!TrySplit) {
|
|
if (tryFoldMemoryOperand(MI, vrm, ReMatDefMI, index,
|
|
Ops, FoldSS, FoldSlot, NewVReg)) {
|
|
// Folding the load/store can completely change the instruction in
|
|
// unpredictable ways, rescan it from the beginning.
|
|
|
|
if (FoldSS) {
|
|
// We need to give the new vreg the same stack slot as the
|
|
// spilled interval.
|
|
vrm.assignVirt2StackSlot(NewVReg, FoldSlot);
|
|
}
|
|
|
|
HasUse = false;
|
|
HasDef = false;
|
|
CanFold = false;
|
|
if (isNotInMIMap(MI))
|
|
break;
|
|
goto RestartInstruction;
|
|
}
|
|
} else {
|
|
// We'll try to fold it later if it's profitable.
|
|
CanFold = canFoldMemoryOperand(MI, Ops, DefIsReMat);
|
|
}
|
|
}
|
|
|
|
mop.setReg(NewVReg);
|
|
if (mop.isImplicit())
|
|
rewriteImplicitOps(li, MI, NewVReg, vrm);
|
|
|
|
// Reuse NewVReg for other reads.
|
|
bool HasEarlyClobber = false;
|
|
for (unsigned j = 0, e = Ops.size(); j != e; ++j) {
|
|
MachineOperand &mopj = MI->getOperand(Ops[j]);
|
|
mopj.setReg(NewVReg);
|
|
if (mopj.isImplicit())
|
|
rewriteImplicitOps(li, MI, NewVReg, vrm);
|
|
if (mopj.isEarlyClobber())
|
|
HasEarlyClobber = true;
|
|
}
|
|
|
|
if (CreatedNewVReg) {
|
|
if (DefIsReMat) {
|
|
vrm.setVirtIsReMaterialized(NewVReg, ReMatDefMI);
|
|
if (ReMatIds[VNI->id] == VirtRegMap::MAX_STACK_SLOT) {
|
|
// Each valnum may have its own remat id.
|
|
ReMatIds[VNI->id] = vrm.assignVirtReMatId(NewVReg);
|
|
} else {
|
|
vrm.assignVirtReMatId(NewVReg, ReMatIds[VNI->id]);
|
|
}
|
|
if (!CanDelete || (HasUse && HasDef)) {
|
|
// If this is a two-addr instruction then its use operands are
|
|
// rematerializable but its def is not. It should be assigned a
|
|
// stack slot.
|
|
vrm.assignVirt2StackSlot(NewVReg, Slot);
|
|
}
|
|
} else {
|
|
vrm.assignVirt2StackSlot(NewVReg, Slot);
|
|
}
|
|
} else if (HasUse && HasDef &&
|
|
vrm.getStackSlot(NewVReg) == VirtRegMap::NO_STACK_SLOT) {
|
|
// If this interval hasn't been assigned a stack slot (because earlier
|
|
// def is a deleted remat def), do it now.
|
|
assert(Slot != VirtRegMap::NO_STACK_SLOT);
|
|
vrm.assignVirt2StackSlot(NewVReg, Slot);
|
|
}
|
|
|
|
// Re-matting an instruction with virtual register use. Add the
|
|
// register as an implicit use on the use MI.
|
|
if (DefIsReMat && ImpUse)
|
|
MI->addOperand(MachineOperand::CreateReg(ImpUse, false, true));
|
|
|
|
// Create a new register interval for this spill / remat.
|
|
LiveInterval &nI = getOrCreateInterval(NewVReg);
|
|
if (CreatedNewVReg) {
|
|
NewLIs.push_back(&nI);
|
|
MBBVRegsMap.insert(std::make_pair(MI->getParent()->getNumber(), NewVReg));
|
|
if (TrySplit)
|
|
vrm.setIsSplitFromReg(NewVReg, li.reg);
|
|
}
|
|
|
|
if (HasUse) {
|
|
if (CreatedNewVReg) {
|
|
LiveRange LR(index.getLoadIndex(), index.getDefIndex(),
|
|
nI.getNextValue(SlotIndex(), 0, VNInfoAllocator));
|
|
DEBUG(dbgs() << " +" << LR);
|
|
nI.addRange(LR);
|
|
} else {
|
|
// Extend the split live interval to this def / use.
|
|
SlotIndex End = index.getDefIndex();
|
|
LiveRange LR(nI.ranges[nI.ranges.size()-1].end, End,
|
|
nI.getValNumInfo(nI.getNumValNums()-1));
|
|
DEBUG(dbgs() << " +" << LR);
|
|
nI.addRange(LR);
|
|
}
|
|
}
|
|
if (HasDef) {
|
|
// An early clobber starts at the use slot, except for an early clobber
|
|
// tied to a use operand (yes, that is a thing).
|
|
LiveRange LR(HasEarlyClobber && !HasUse ?
|
|
index.getUseIndex() : index.getDefIndex(),
|
|
index.getStoreIndex(),
|
|
nI.getNextValue(SlotIndex(), 0, VNInfoAllocator));
|
|
DEBUG(dbgs() << " +" << LR);
|
|
nI.addRange(LR);
|
|
}
|
|
|
|
DEBUG({
|
|
dbgs() << "\t\t\t\tAdded new interval: ";
|
|
nI.print(dbgs(), tri_);
|
|
dbgs() << '\n';
|
|
});
|
|
}
|
|
return CanFold;
|
|
}
|
|
bool LiveIntervals::anyKillInMBBAfterIdx(const LiveInterval &li,
|
|
const VNInfo *VNI,
|
|
MachineBasicBlock *MBB,
|
|
SlotIndex Idx) const {
|
|
return li.killedInRange(Idx.getNextSlot(), getMBBEndIdx(MBB));
|
|
}
|
|
|
|
/// RewriteInfo - Keep track of machine instrs that will be rewritten
|
|
/// during spilling.
|
|
namespace {
|
|
struct RewriteInfo {
|
|
SlotIndex Index;
|
|
MachineInstr *MI;
|
|
RewriteInfo(SlotIndex i, MachineInstr *mi) : Index(i), MI(mi) {}
|
|
};
|
|
|
|
struct RewriteInfoCompare {
|
|
bool operator()(const RewriteInfo &LHS, const RewriteInfo &RHS) const {
|
|
return LHS.Index < RHS.Index;
|
|
}
|
|
};
|
|
}
|
|
|
|
void LiveIntervals::
|
|
rewriteInstructionsForSpills(const LiveInterval &li, bool TrySplit,
|
|
LiveInterval::Ranges::const_iterator &I,
|
|
MachineInstr *ReMatOrigDefMI, MachineInstr *ReMatDefMI,
|
|
unsigned Slot, int LdSlot,
|
|
bool isLoad, bool isLoadSS, bool DefIsReMat, bool CanDelete,
|
|
VirtRegMap &vrm,
|
|
const TargetRegisterClass* rc,
|
|
SmallVector<int, 4> &ReMatIds,
|
|
const MachineLoopInfo *loopInfo,
|
|
BitVector &SpillMBBs,
|
|
DenseMap<unsigned, std::vector<SRInfo> > &SpillIdxes,
|
|
BitVector &RestoreMBBs,
|
|
DenseMap<unsigned, std::vector<SRInfo> > &RestoreIdxes,
|
|
DenseMap<unsigned,unsigned> &MBBVRegsMap,
|
|
std::vector<LiveInterval*> &NewLIs) {
|
|
bool AllCanFold = true;
|
|
unsigned NewVReg = 0;
|
|
SlotIndex start = I->start.getBaseIndex();
|
|
SlotIndex end = I->end.getPrevSlot().getBaseIndex().getNextIndex();
|
|
|
|
// First collect all the def / use in this live range that will be rewritten.
|
|
// Make sure they are sorted according to instruction index.
|
|
std::vector<RewriteInfo> RewriteMIs;
|
|
for (MachineRegisterInfo::reg_iterator ri = mri_->reg_begin(li.reg),
|
|
re = mri_->reg_end(); ri != re; ) {
|
|
MachineInstr *MI = &*ri;
|
|
MachineOperand &O = ri.getOperand();
|
|
++ri;
|
|
if (MI->isDebugValue()) {
|
|
// Modify DBG_VALUE now that the value is in a spill slot.
|
|
if (Slot != VirtRegMap::MAX_STACK_SLOT || isLoadSS) {
|
|
uint64_t Offset = MI->getOperand(1).getImm();
|
|
const MDNode *MDPtr = MI->getOperand(2).getMetadata();
|
|
DebugLoc DL = MI->getDebugLoc();
|
|
int FI = isLoadSS ? LdSlot : (int)Slot;
|
|
if (MachineInstr *NewDV = tii_->emitFrameIndexDebugValue(*mf_, FI,
|
|
Offset, MDPtr, DL)) {
|
|
DEBUG(dbgs() << "Modifying debug info due to spill:" << "\t" << *MI);
|
|
ReplaceMachineInstrInMaps(MI, NewDV);
|
|
MachineBasicBlock *MBB = MI->getParent();
|
|
MBB->insert(MBB->erase(MI), NewDV);
|
|
continue;
|
|
}
|
|
}
|
|
|
|
DEBUG(dbgs() << "Removing debug info due to spill:" << "\t" << *MI);
|
|
RemoveMachineInstrFromMaps(MI);
|
|
vrm.RemoveMachineInstrFromMaps(MI);
|
|
MI->eraseFromParent();
|
|
continue;
|
|
}
|
|
assert(!(O.isImplicit() && O.isUse()) &&
|
|
"Spilling register that's used as implicit use?");
|
|
SlotIndex index = getInstructionIndex(MI);
|
|
if (index < start || index >= end)
|
|
continue;
|
|
|
|
if (O.isUndef())
|
|
// 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.
|
|
continue;
|
|
RewriteMIs.push_back(RewriteInfo(index, MI));
|
|
}
|
|
std::sort(RewriteMIs.begin(), RewriteMIs.end(), RewriteInfoCompare());
|
|
|
|
unsigned ImpUse = DefIsReMat ? getReMatImplicitUse(li, ReMatDefMI) : 0;
|
|
// Now rewrite the defs and uses.
|
|
for (unsigned i = 0, e = RewriteMIs.size(); i != e; ) {
|
|
RewriteInfo &rwi = RewriteMIs[i];
|
|
++i;
|
|
SlotIndex index = rwi.Index;
|
|
MachineInstr *MI = rwi.MI;
|
|
// If MI def and/or use the same register multiple times, then there
|
|
// are multiple entries.
|
|
while (i != e && RewriteMIs[i].MI == MI) {
|
|
assert(RewriteMIs[i].Index == index);
|
|
++i;
|
|
}
|
|
MachineBasicBlock *MBB = MI->getParent();
|
|
|
|
if (ImpUse && MI != ReMatDefMI) {
|
|
// Re-matting an instruction with virtual register use. Prevent interval
|
|
// from being spilled.
|
|
getInterval(ImpUse).markNotSpillable();
|
|
}
|
|
|
|
unsigned MBBId = MBB->getNumber();
|
|
unsigned ThisVReg = 0;
|
|
if (TrySplit) {
|
|
DenseMap<unsigned,unsigned>::iterator NVI = MBBVRegsMap.find(MBBId);
|
|
if (NVI != MBBVRegsMap.end()) {
|
|
ThisVReg = NVI->second;
|
|
// One common case:
|
|
// x = use
|
|
// ...
|
|
// ...
|
|
// def = ...
|
|
// = use
|
|
// It's better to start a new interval to avoid artifically
|
|
// extend the new interval.
|
|
if (MI->readsWritesVirtualRegister(li.reg) ==
|
|
std::make_pair(false,true)) {
|
|
MBBVRegsMap.erase(MBB->getNumber());
|
|
ThisVReg = 0;
|
|
}
|
|
}
|
|
}
|
|
|
|
bool IsNew = ThisVReg == 0;
|
|
if (IsNew) {
|
|
// This ends the previous live interval. If all of its def / use
|
|
// can be folded, give it a low spill weight.
|
|
if (NewVReg && TrySplit && AllCanFold) {
|
|
LiveInterval &nI = getOrCreateInterval(NewVReg);
|
|
nI.weight /= 10.0F;
|
|
}
|
|
AllCanFold = true;
|
|
}
|
|
NewVReg = ThisVReg;
|
|
|
|
bool HasDef = false;
|
|
bool HasUse = false;
|
|
bool CanFold = rewriteInstructionForSpills(li, I->valno, TrySplit,
|
|
index, end, MI, ReMatOrigDefMI, ReMatDefMI,
|
|
Slot, LdSlot, isLoad, isLoadSS, DefIsReMat,
|
|
CanDelete, vrm, rc, ReMatIds, loopInfo, NewVReg,
|
|
ImpUse, HasDef, HasUse, MBBVRegsMap, NewLIs);
|
|
if (!HasDef && !HasUse)
|
|
continue;
|
|
|
|
AllCanFold &= CanFold;
|
|
|
|
// Update weight of spill interval.
|
|
LiveInterval &nI = getOrCreateInterval(NewVReg);
|
|
if (!TrySplit) {
|
|
// The spill weight is now infinity as it cannot be spilled again.
|
|
nI.markNotSpillable();
|
|
continue;
|
|
}
|
|
|
|
// Keep track of the last def and first use in each MBB.
|
|
if (HasDef) {
|
|
if (MI != ReMatOrigDefMI || !CanDelete) {
|
|
bool HasKill = false;
|
|
if (!HasUse)
|
|
HasKill = anyKillInMBBAfterIdx(li, I->valno, MBB, index.getDefIndex());
|
|
else {
|
|
// If this is a two-address code, then this index starts a new VNInfo.
|
|
const VNInfo *VNI = li.findDefinedVNInfoForRegInt(index.getDefIndex());
|
|
if (VNI)
|
|
HasKill = anyKillInMBBAfterIdx(li, VNI, MBB, index.getDefIndex());
|
|
}
|
|
DenseMap<unsigned, std::vector<SRInfo> >::iterator SII =
|
|
SpillIdxes.find(MBBId);
|
|
if (!HasKill) {
|
|
if (SII == SpillIdxes.end()) {
|
|
std::vector<SRInfo> S;
|
|
S.push_back(SRInfo(index, NewVReg, true));
|
|
SpillIdxes.insert(std::make_pair(MBBId, S));
|
|
} else if (SII->second.back().vreg != NewVReg) {
|
|
SII->second.push_back(SRInfo(index, NewVReg, true));
|
|
} else if (index > SII->second.back().index) {
|
|
// If there is an earlier def and this is a two-address
|
|
// instruction, then it's not possible to fold the store (which
|
|
// would also fold the load).
|
|
SRInfo &Info = SII->second.back();
|
|
Info.index = index;
|
|
Info.canFold = !HasUse;
|
|
}
|
|
SpillMBBs.set(MBBId);
|
|
} else if (SII != SpillIdxes.end() &&
|
|
SII->second.back().vreg == NewVReg &&
|
|
index > SII->second.back().index) {
|
|
// There is an earlier def that's not killed (must be two-address).
|
|
// The spill is no longer needed.
|
|
SII->second.pop_back();
|
|
if (SII->second.empty()) {
|
|
SpillIdxes.erase(MBBId);
|
|
SpillMBBs.reset(MBBId);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
if (HasUse) {
|
|
DenseMap<unsigned, std::vector<SRInfo> >::iterator SII =
|
|
SpillIdxes.find(MBBId);
|
|
if (SII != SpillIdxes.end() &&
|
|
SII->second.back().vreg == NewVReg &&
|
|
index > SII->second.back().index)
|
|
// Use(s) following the last def, it's not safe to fold the spill.
|
|
SII->second.back().canFold = false;
|
|
DenseMap<unsigned, std::vector<SRInfo> >::iterator RII =
|
|
RestoreIdxes.find(MBBId);
|
|
if (RII != RestoreIdxes.end() && RII->second.back().vreg == NewVReg)
|
|
// If we are splitting live intervals, only fold if it's the first
|
|
// use and there isn't another use later in the MBB.
|
|
RII->second.back().canFold = false;
|
|
else if (IsNew) {
|
|
// Only need a reload if there isn't an earlier def / use.
|
|
if (RII == RestoreIdxes.end()) {
|
|
std::vector<SRInfo> Infos;
|
|
Infos.push_back(SRInfo(index, NewVReg, true));
|
|
RestoreIdxes.insert(std::make_pair(MBBId, Infos));
|
|
} else {
|
|
RII->second.push_back(SRInfo(index, NewVReg, true));
|
|
}
|
|
RestoreMBBs.set(MBBId);
|
|
}
|
|
}
|
|
|
|
// Update spill weight.
|
|
unsigned loopDepth = loopInfo->getLoopDepth(MBB);
|
|
nI.weight += getSpillWeight(HasDef, HasUse, loopDepth);
|
|
}
|
|
|
|
if (NewVReg && TrySplit && AllCanFold) {
|
|
// If all of its def / use can be folded, give it a low spill weight.
|
|
LiveInterval &nI = getOrCreateInterval(NewVReg);
|
|
nI.weight /= 10.0F;
|
|
}
|
|
}
|
|
|
|
bool LiveIntervals::alsoFoldARestore(int Id, SlotIndex index,
|
|
unsigned vr, BitVector &RestoreMBBs,
|
|
DenseMap<unsigned,std::vector<SRInfo> > &RestoreIdxes) {
|
|
if (!RestoreMBBs[Id])
|
|
return false;
|
|
std::vector<SRInfo> &Restores = RestoreIdxes[Id];
|
|
for (unsigned i = 0, e = Restores.size(); i != e; ++i)
|
|
if (Restores[i].index == index &&
|
|
Restores[i].vreg == vr &&
|
|
Restores[i].canFold)
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
void LiveIntervals::eraseRestoreInfo(int Id, SlotIndex index,
|
|
unsigned vr, BitVector &RestoreMBBs,
|
|
DenseMap<unsigned,std::vector<SRInfo> > &RestoreIdxes) {
|
|
if (!RestoreMBBs[Id])
|
|
return;
|
|
std::vector<SRInfo> &Restores = RestoreIdxes[Id];
|
|
for (unsigned i = 0, e = Restores.size(); i != e; ++i)
|
|
if (Restores[i].index == index && Restores[i].vreg)
|
|
Restores[i].index = SlotIndex();
|
|
}
|
|
|
|
/// handleSpilledImpDefs - Remove IMPLICIT_DEF instructions which are being
|
|
/// spilled and create empty intervals for their uses.
|
|
void
|
|
LiveIntervals::handleSpilledImpDefs(const LiveInterval &li, VirtRegMap &vrm,
|
|
const TargetRegisterClass* rc,
|
|
std::vector<LiveInterval*> &NewLIs) {
|
|
for (MachineRegisterInfo::reg_iterator ri = mri_->reg_begin(li.reg),
|
|
re = mri_->reg_end(); ri != re; ) {
|
|
MachineOperand &O = ri.getOperand();
|
|
MachineInstr *MI = &*ri;
|
|
++ri;
|
|
if (MI->isDebugValue()) {
|
|
// Remove debug info for now.
|
|
O.setReg(0U);
|
|
DEBUG(dbgs() << "Removing debug info due to spill:" << "\t" << *MI);
|
|
continue;
|
|
}
|
|
if (O.isDef()) {
|
|
assert(MI->isImplicitDef() &&
|
|
"Register def was not rewritten?");
|
|
RemoveMachineInstrFromMaps(MI);
|
|
vrm.RemoveMachineInstrFromMaps(MI);
|
|
MI->eraseFromParent();
|
|
} else {
|
|
// This must be an use of an implicit_def so it's not part of the live
|
|
// interval. Create a new empty live interval for it.
|
|
// FIXME: Can we simply erase some of the instructions? e.g. Stores?
|
|
unsigned NewVReg = mri_->createVirtualRegister(rc);
|
|
vrm.grow();
|
|
vrm.setIsImplicitlyDefined(NewVReg);
|
|
NewLIs.push_back(&getOrCreateInterval(NewVReg));
|
|
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
if (MO.isReg() && MO.getReg() == li.reg) {
|
|
MO.setReg(NewVReg);
|
|
MO.setIsUndef();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
float
|
|
LiveIntervals::getSpillWeight(bool isDef, bool isUse, unsigned loopDepth) {
|
|
// Limit the loop depth ridiculousness.
|
|
if (loopDepth > 200)
|
|
loopDepth = 200;
|
|
|
|
// The loop depth is used to roughly estimate the number of times the
|
|
// instruction is executed. Something like 10^d is simple, but will quickly
|
|
// overflow a float. This expression behaves like 10^d for small d, but is
|
|
// more tempered for large d. At d=200 we get 6.7e33 which leaves a bit of
|
|
// headroom before overflow.
|
|
float lc = std::pow(1 + (100.0f / (loopDepth+10)), (float)loopDepth);
|
|
|
|
return (isDef + isUse) * lc;
|
|
}
|
|
|
|
void
|
|
LiveIntervals::normalizeSpillWeights(std::vector<LiveInterval*> &NewLIs) {
|
|
for (unsigned i = 0, e = NewLIs.size(); i != e; ++i)
|
|
normalizeSpillWeight(*NewLIs[i]);
|
|
}
|
|
|
|
std::vector<LiveInterval*> LiveIntervals::
|
|
addIntervalsForSpills(const LiveInterval &li,
|
|
const SmallVectorImpl<LiveInterval*> &SpillIs,
|
|
const MachineLoopInfo *loopInfo, VirtRegMap &vrm) {
|
|
assert(li.isSpillable() && "attempt to spill already spilled interval!");
|
|
|
|
DEBUG({
|
|
dbgs() << "\t\t\t\tadding intervals for spills for interval: ";
|
|
li.print(dbgs(), tri_);
|
|
dbgs() << '\n';
|
|
});
|
|
|
|
// Each bit specify whether a spill is required in the MBB.
|
|
BitVector SpillMBBs(mf_->getNumBlockIDs());
|
|
DenseMap<unsigned, std::vector<SRInfo> > SpillIdxes;
|
|
BitVector RestoreMBBs(mf_->getNumBlockIDs());
|
|
DenseMap<unsigned, std::vector<SRInfo> > RestoreIdxes;
|
|
DenseMap<unsigned,unsigned> MBBVRegsMap;
|
|
std::vector<LiveInterval*> NewLIs;
|
|
const TargetRegisterClass* rc = mri_->getRegClass(li.reg);
|
|
|
|
unsigned NumValNums = li.getNumValNums();
|
|
SmallVector<MachineInstr*, 4> ReMatDefs;
|
|
ReMatDefs.resize(NumValNums, NULL);
|
|
SmallVector<MachineInstr*, 4> ReMatOrigDefs;
|
|
ReMatOrigDefs.resize(NumValNums, NULL);
|
|
SmallVector<int, 4> ReMatIds;
|
|
ReMatIds.resize(NumValNums, VirtRegMap::MAX_STACK_SLOT);
|
|
BitVector ReMatDelete(NumValNums);
|
|
unsigned Slot = VirtRegMap::MAX_STACK_SLOT;
|
|
|
|
// Spilling a split live interval. It cannot be split any further. Also,
|
|
// it's also guaranteed to be a single val# / range interval.
|
|
if (vrm.getPreSplitReg(li.reg)) {
|
|
vrm.setIsSplitFromReg(li.reg, 0);
|
|
// Unset the split kill marker on the last use.
|
|
SlotIndex KillIdx = vrm.getKillPoint(li.reg);
|
|
if (KillIdx != SlotIndex()) {
|
|
MachineInstr *KillMI = getInstructionFromIndex(KillIdx);
|
|
assert(KillMI && "Last use disappeared?");
|
|
int KillOp = KillMI->findRegisterUseOperandIdx(li.reg, true);
|
|
assert(KillOp != -1 && "Last use disappeared?");
|
|
KillMI->getOperand(KillOp).setIsKill(false);
|
|
}
|
|
vrm.removeKillPoint(li.reg);
|
|
bool DefIsReMat = vrm.isReMaterialized(li.reg);
|
|
Slot = vrm.getStackSlot(li.reg);
|
|
assert(Slot != VirtRegMap::MAX_STACK_SLOT);
|
|
MachineInstr *ReMatDefMI = DefIsReMat ?
|
|
vrm.getReMaterializedMI(li.reg) : NULL;
|
|
int LdSlot = 0;
|
|
bool isLoadSS = DefIsReMat && tii_->isLoadFromStackSlot(ReMatDefMI, LdSlot);
|
|
bool isLoad = isLoadSS ||
|
|
(DefIsReMat && (ReMatDefMI->getDesc().canFoldAsLoad()));
|
|
bool IsFirstRange = true;
|
|
for (LiveInterval::Ranges::const_iterator
|
|
I = li.ranges.begin(), E = li.ranges.end(); I != E; ++I) {
|
|
// If this is a split live interval with multiple ranges, it means there
|
|
// are two-address instructions that re-defined the value. Only the
|
|
// first def can be rematerialized!
|
|
if (IsFirstRange) {
|
|
// Note ReMatOrigDefMI has already been deleted.
|
|
rewriteInstructionsForSpills(li, false, I, NULL, ReMatDefMI,
|
|
Slot, LdSlot, isLoad, isLoadSS, DefIsReMat,
|
|
false, vrm, rc, ReMatIds, loopInfo,
|
|
SpillMBBs, SpillIdxes, RestoreMBBs, RestoreIdxes,
|
|
MBBVRegsMap, NewLIs);
|
|
} else {
|
|
rewriteInstructionsForSpills(li, false, I, NULL, 0,
|
|
Slot, 0, false, false, false,
|
|
false, vrm, rc, ReMatIds, loopInfo,
|
|
SpillMBBs, SpillIdxes, RestoreMBBs, RestoreIdxes,
|
|
MBBVRegsMap, NewLIs);
|
|
}
|
|
IsFirstRange = false;
|
|
}
|
|
|
|
handleSpilledImpDefs(li, vrm, rc, NewLIs);
|
|
normalizeSpillWeights(NewLIs);
|
|
return NewLIs;
|
|
}
|
|
|
|
bool TrySplit = !intervalIsInOneMBB(li);
|
|
if (TrySplit)
|
|
++numSplits;
|
|
bool NeedStackSlot = false;
|
|
for (LiveInterval::const_vni_iterator i = li.vni_begin(), e = li.vni_end();
|
|
i != e; ++i) {
|
|
const VNInfo *VNI = *i;
|
|
unsigned VN = VNI->id;
|
|
if (VNI->isUnused())
|
|
continue; // Dead val#.
|
|
// Is the def for the val# rematerializable?
|
|
MachineInstr *ReMatDefMI = getInstructionFromIndex(VNI->def);
|
|
bool dummy;
|
|
if (ReMatDefMI && isReMaterializable(li, VNI, ReMatDefMI, SpillIs, dummy)) {
|
|
// Remember how to remat the def of this val#.
|
|
ReMatOrigDefs[VN] = ReMatDefMI;
|
|
// Original def may be modified so we have to make a copy here.
|
|
MachineInstr *Clone = mf_->CloneMachineInstr(ReMatDefMI);
|
|
CloneMIs.push_back(Clone);
|
|
ReMatDefs[VN] = Clone;
|
|
|
|
bool CanDelete = true;
|
|
if (VNI->hasPHIKill()) {
|
|
// A kill is a phi node, not all of its uses can be rematerialized.
|
|
// It must not be deleted.
|
|
CanDelete = false;
|
|
// Need a stack slot if there is any live range where uses cannot be
|
|
// rematerialized.
|
|
NeedStackSlot = true;
|
|
}
|
|
if (CanDelete)
|
|
ReMatDelete.set(VN);
|
|
} else {
|
|
// Need a stack slot if there is any live range where uses cannot be
|
|
// rematerialized.
|
|
NeedStackSlot = true;
|
|
}
|
|
}
|
|
|
|
// One stack slot per live interval.
|
|
if (NeedStackSlot && vrm.getPreSplitReg(li.reg) == 0) {
|
|
if (vrm.getStackSlot(li.reg) == VirtRegMap::NO_STACK_SLOT)
|
|
Slot = vrm.assignVirt2StackSlot(li.reg);
|
|
|
|
// This case only occurs when the prealloc splitter has already assigned
|
|
// a stack slot to this vreg.
|
|
else
|
|
Slot = vrm.getStackSlot(li.reg);
|
|
}
|
|
|
|
// Create new intervals and rewrite defs and uses.
|
|
for (LiveInterval::Ranges::const_iterator
|
|
I = li.ranges.begin(), E = li.ranges.end(); I != E; ++I) {
|
|
MachineInstr *ReMatDefMI = ReMatDefs[I->valno->id];
|
|
MachineInstr *ReMatOrigDefMI = ReMatOrigDefs[I->valno->id];
|
|
bool DefIsReMat = ReMatDefMI != NULL;
|
|
bool CanDelete = ReMatDelete[I->valno->id];
|
|
int LdSlot = 0;
|
|
bool isLoadSS = DefIsReMat && tii_->isLoadFromStackSlot(ReMatDefMI, LdSlot);
|
|
bool isLoad = isLoadSS ||
|
|
(DefIsReMat && ReMatDefMI->getDesc().canFoldAsLoad());
|
|
rewriteInstructionsForSpills(li, TrySplit, I, ReMatOrigDefMI, ReMatDefMI,
|
|
Slot, LdSlot, isLoad, isLoadSS, DefIsReMat,
|
|
CanDelete, vrm, rc, ReMatIds, loopInfo,
|
|
SpillMBBs, SpillIdxes, RestoreMBBs, RestoreIdxes,
|
|
MBBVRegsMap, NewLIs);
|
|
}
|
|
|
|
// Insert spills / restores if we are splitting.
|
|
if (!TrySplit) {
|
|
handleSpilledImpDefs(li, vrm, rc, NewLIs);
|
|
normalizeSpillWeights(NewLIs);
|
|
return NewLIs;
|
|
}
|
|
|
|
SmallPtrSet<LiveInterval*, 4> AddedKill;
|
|
SmallVector<unsigned, 2> Ops;
|
|
if (NeedStackSlot) {
|
|
int Id = SpillMBBs.find_first();
|
|
while (Id != -1) {
|
|
std::vector<SRInfo> &spills = SpillIdxes[Id];
|
|
for (unsigned i = 0, e = spills.size(); i != e; ++i) {
|
|
SlotIndex index = spills[i].index;
|
|
unsigned VReg = spills[i].vreg;
|
|
LiveInterval &nI = getOrCreateInterval(VReg);
|
|
bool isReMat = vrm.isReMaterialized(VReg);
|
|
MachineInstr *MI = getInstructionFromIndex(index);
|
|
bool CanFold = false;
|
|
bool FoundUse = false;
|
|
Ops.clear();
|
|
if (spills[i].canFold) {
|
|
CanFold = true;
|
|
for (unsigned j = 0, ee = MI->getNumOperands(); j != ee; ++j) {
|
|
MachineOperand &MO = MI->getOperand(j);
|
|
if (!MO.isReg() || MO.getReg() != VReg)
|
|
continue;
|
|
|
|
Ops.push_back(j);
|
|
if (MO.isDef())
|
|
continue;
|
|
if (isReMat ||
|
|
(!FoundUse && !alsoFoldARestore(Id, index, VReg,
|
|
RestoreMBBs, RestoreIdxes))) {
|
|
// MI has two-address uses of the same register. If the use
|
|
// isn't the first and only use in the BB, then we can't fold
|
|
// it. FIXME: Move this to rewriteInstructionsForSpills.
|
|
CanFold = false;
|
|
break;
|
|
}
|
|
FoundUse = true;
|
|
}
|
|
}
|
|
// Fold the store into the def if possible.
|
|
bool Folded = false;
|
|
if (CanFold && !Ops.empty()) {
|
|
if (tryFoldMemoryOperand(MI, vrm, NULL, index, Ops, true, Slot,VReg)){
|
|
Folded = true;
|
|
if (FoundUse) {
|
|
// Also folded uses, do not issue a load.
|
|
eraseRestoreInfo(Id, index, VReg, RestoreMBBs, RestoreIdxes);
|
|
nI.removeRange(index.getLoadIndex(), index.getDefIndex());
|
|
}
|
|
nI.removeRange(index.getDefIndex(), index.getStoreIndex());
|
|
}
|
|
}
|
|
|
|
// Otherwise tell the spiller to issue a spill.
|
|
if (!Folded) {
|
|
LiveRange *LR = &nI.ranges[nI.ranges.size()-1];
|
|
bool isKill = LR->end == index.getStoreIndex();
|
|
if (!MI->registerDefIsDead(nI.reg))
|
|
// No need to spill a dead def.
|
|
vrm.addSpillPoint(VReg, isKill, MI);
|
|
if (isKill)
|
|
AddedKill.insert(&nI);
|
|
}
|
|
}
|
|
Id = SpillMBBs.find_next(Id);
|
|
}
|
|
}
|
|
|
|
int Id = RestoreMBBs.find_first();
|
|
while (Id != -1) {
|
|
std::vector<SRInfo> &restores = RestoreIdxes[Id];
|
|
for (unsigned i = 0, e = restores.size(); i != e; ++i) {
|
|
SlotIndex index = restores[i].index;
|
|
if (index == SlotIndex())
|
|
continue;
|
|
unsigned VReg = restores[i].vreg;
|
|
LiveInterval &nI = getOrCreateInterval(VReg);
|
|
bool isReMat = vrm.isReMaterialized(VReg);
|
|
MachineInstr *MI = getInstructionFromIndex(index);
|
|
bool CanFold = false;
|
|
Ops.clear();
|
|
if (restores[i].canFold) {
|
|
CanFold = true;
|
|
for (unsigned j = 0, ee = MI->getNumOperands(); j != ee; ++j) {
|
|
MachineOperand &MO = MI->getOperand(j);
|
|
if (!MO.isReg() || MO.getReg() != VReg)
|
|
continue;
|
|
|
|
if (MO.isDef()) {
|
|
// If this restore were to be folded, it would have been folded
|
|
// already.
|
|
CanFold = false;
|
|
break;
|
|
}
|
|
Ops.push_back(j);
|
|
}
|
|
}
|
|
|
|
// Fold the load into the use if possible.
|
|
bool Folded = false;
|
|
if (CanFold && !Ops.empty()) {
|
|
if (!isReMat)
|
|
Folded = tryFoldMemoryOperand(MI, vrm, NULL,index,Ops,true,Slot,VReg);
|
|
else {
|
|
MachineInstr *ReMatDefMI = vrm.getReMaterializedMI(VReg);
|
|
int LdSlot = 0;
|
|
bool isLoadSS = tii_->isLoadFromStackSlot(ReMatDefMI, LdSlot);
|
|
// If the rematerializable def is a load, also try to fold it.
|
|
if (isLoadSS || ReMatDefMI->getDesc().canFoldAsLoad())
|
|
Folded = tryFoldMemoryOperand(MI, vrm, ReMatDefMI, index,
|
|
Ops, isLoadSS, LdSlot, VReg);
|
|
if (!Folded) {
|
|
unsigned ImpUse = getReMatImplicitUse(li, ReMatDefMI);
|
|
if (ImpUse) {
|
|
// Re-matting an instruction with virtual register use. Add the
|
|
// register as an implicit use on the use MI and mark the register
|
|
// interval as unspillable.
|
|
LiveInterval &ImpLi = getInterval(ImpUse);
|
|
ImpLi.markNotSpillable();
|
|
MI->addOperand(MachineOperand::CreateReg(ImpUse, false, true));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
// If folding is not possible / failed, then tell the spiller to issue a
|
|
// load / rematerialization for us.
|
|
if (Folded)
|
|
nI.removeRange(index.getLoadIndex(), index.getDefIndex());
|
|
else
|
|
vrm.addRestorePoint(VReg, MI);
|
|
}
|
|
Id = RestoreMBBs.find_next(Id);
|
|
}
|
|
|
|
// Finalize intervals: add kills, finalize spill weights, and filter out
|
|
// dead intervals.
|
|
std::vector<LiveInterval*> RetNewLIs;
|
|
for (unsigned i = 0, e = NewLIs.size(); i != e; ++i) {
|
|
LiveInterval *LI = NewLIs[i];
|
|
if (!LI->empty()) {
|
|
if (!AddedKill.count(LI)) {
|
|
LiveRange *LR = &LI->ranges[LI->ranges.size()-1];
|
|
SlotIndex LastUseIdx = LR->end.getBaseIndex();
|
|
MachineInstr *LastUse = getInstructionFromIndex(LastUseIdx);
|
|
int UseIdx = LastUse->findRegisterUseOperandIdx(LI->reg, false);
|
|
assert(UseIdx != -1);
|
|
if (!LastUse->isRegTiedToDefOperand(UseIdx)) {
|
|
LastUse->getOperand(UseIdx).setIsKill();
|
|
vrm.addKillPoint(LI->reg, LastUseIdx);
|
|
}
|
|
}
|
|
RetNewLIs.push_back(LI);
|
|
}
|
|
}
|
|
|
|
handleSpilledImpDefs(li, vrm, rc, RetNewLIs);
|
|
normalizeSpillWeights(RetNewLIs);
|
|
return RetNewLIs;
|
|
}
|
|
|
|
/// hasAllocatableSuperReg - Return true if the specified physical register has
|
|
/// any super register that's allocatable.
|
|
bool LiveIntervals::hasAllocatableSuperReg(unsigned Reg) const {
|
|
for (const unsigned* AS = tri_->getSuperRegisters(Reg); *AS; ++AS)
|
|
if (allocatableRegs_[*AS] && hasInterval(*AS))
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
/// getRepresentativeReg - Find the largest super register of the specified
|
|
/// physical register.
|
|
unsigned LiveIntervals::getRepresentativeReg(unsigned Reg) const {
|
|
// Find the largest super-register that is allocatable.
|
|
unsigned BestReg = Reg;
|
|
for (const unsigned* AS = tri_->getSuperRegisters(Reg); *AS; ++AS) {
|
|
unsigned SuperReg = *AS;
|
|
if (!hasAllocatableSuperReg(SuperReg) && hasInterval(SuperReg)) {
|
|
BestReg = SuperReg;
|
|
break;
|
|
}
|
|
}
|
|
return BestReg;
|
|
}
|
|
|
|
/// getNumConflictsWithPhysReg - Return the number of uses and defs of the
|
|
/// specified interval that conflicts with the specified physical register.
|
|
unsigned LiveIntervals::getNumConflictsWithPhysReg(const LiveInterval &li,
|
|
unsigned PhysReg) const {
|
|
unsigned NumConflicts = 0;
|
|
const LiveInterval &pli = getInterval(getRepresentativeReg(PhysReg));
|
|
for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(li.reg),
|
|
E = mri_->reg_end(); I != E; ++I) {
|
|
MachineOperand &O = I.getOperand();
|
|
MachineInstr *MI = O.getParent();
|
|
if (MI->isDebugValue())
|
|
continue;
|
|
SlotIndex Index = getInstructionIndex(MI);
|
|
if (pli.liveAt(Index))
|
|
++NumConflicts;
|
|
}
|
|
return NumConflicts;
|
|
}
|
|
|
|
/// spillPhysRegAroundRegDefsUses - Spill the specified physical register
|
|
/// around all defs and uses of the specified interval. Return true if it
|
|
/// was able to cut its interval.
|
|
bool LiveIntervals::spillPhysRegAroundRegDefsUses(const LiveInterval &li,
|
|
unsigned PhysReg, VirtRegMap &vrm) {
|
|
unsigned SpillReg = getRepresentativeReg(PhysReg);
|
|
|
|
DEBUG(dbgs() << "spillPhysRegAroundRegDefsUses " << tri_->getName(PhysReg)
|
|
<< " represented by " << tri_->getName(SpillReg) << '\n');
|
|
|
|
for (const unsigned *AS = tri_->getAliasSet(PhysReg); *AS; ++AS)
|
|
// If there are registers which alias PhysReg, but which are not a
|
|
// sub-register of the chosen representative super register. Assert
|
|
// since we can't handle it yet.
|
|
assert(*AS == SpillReg || !allocatableRegs_[*AS] || !hasInterval(*AS) ||
|
|
tri_->isSuperRegister(*AS, SpillReg));
|
|
|
|
bool Cut = false;
|
|
SmallVector<unsigned, 4> PRegs;
|
|
if (hasInterval(SpillReg))
|
|
PRegs.push_back(SpillReg);
|
|
for (const unsigned *SR = tri_->getSubRegisters(SpillReg); *SR; ++SR)
|
|
if (hasInterval(*SR))
|
|
PRegs.push_back(*SR);
|
|
|
|
DEBUG({
|
|
dbgs() << "Trying to spill:";
|
|
for (unsigned i = 0, e = PRegs.size(); i != e; ++i)
|
|
dbgs() << ' ' << tri_->getName(PRegs[i]);
|
|
dbgs() << '\n';
|
|
});
|
|
|
|
SmallPtrSet<MachineInstr*, 8> SeenMIs;
|
|
for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(li.reg),
|
|
E = mri_->reg_end(); I != E; ++I) {
|
|
MachineOperand &O = I.getOperand();
|
|
MachineInstr *MI = O.getParent();
|
|
if (MI->isDebugValue() || SeenMIs.count(MI))
|
|
continue;
|
|
SeenMIs.insert(MI);
|
|
SlotIndex Index = getInstructionIndex(MI);
|
|
bool LiveReg = false;
|
|
for (unsigned i = 0, e = PRegs.size(); i != e; ++i) {
|
|
unsigned PReg = PRegs[i];
|
|
LiveInterval &pli = getInterval(PReg);
|
|
if (!pli.liveAt(Index))
|
|
continue;
|
|
LiveReg = true;
|
|
SlotIndex StartIdx = Index.getLoadIndex();
|
|
SlotIndex EndIdx = Index.getNextIndex().getBaseIndex();
|
|
if (!pli.isInOneLiveRange(StartIdx, EndIdx)) {
|
|
std::string msg;
|
|
raw_string_ostream Msg(msg);
|
|
Msg << "Ran out of registers during register allocation!";
|
|
if (MI->isInlineAsm()) {
|
|
Msg << "\nPlease check your inline asm statement for invalid "
|
|
<< "constraints:\n";
|
|
MI->print(Msg, tm_);
|
|
}
|
|
report_fatal_error(Msg.str());
|
|
}
|
|
pli.removeRange(StartIdx, EndIdx);
|
|
LiveReg = true;
|
|
}
|
|
if (!LiveReg)
|
|
continue;
|
|
DEBUG(dbgs() << "Emergency spill around " << Index << '\t' << *MI);
|
|
vrm.addEmergencySpill(SpillReg, MI);
|
|
Cut = true;
|
|
}
|
|
return Cut;
|
|
}
|
|
|
|
LiveRange LiveIntervals::addLiveRangeToEndOfBlock(unsigned reg,
|
|
MachineInstr* startInst) {
|
|
LiveInterval& Interval = getOrCreateInterval(reg);
|
|
VNInfo* VN = Interval.getNextValue(
|
|
SlotIndex(getInstructionIndex(startInst).getDefIndex()),
|
|
startInst, getVNInfoAllocator());
|
|
VN->setHasPHIKill(true);
|
|
LiveRange LR(
|
|
SlotIndex(getInstructionIndex(startInst).getDefIndex()),
|
|
getMBBEndIdx(startInst->getParent()), VN);
|
|
Interval.addRange(LR);
|
|
|
|
return LR;
|
|
}
|
|
|