forked from OSchip/llvm-project
1292 lines
46 KiB
C++
1292 lines
46 KiB
C++
//===-------- InlineSpiller.cpp - Insert spills and restores inline -------===//
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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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// The inline spiller modifies the machine function directly instead of
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// inserting spills and restores in VirtRegMap.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "regalloc"
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#include "Spiller.h"
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#include "VirtRegMap.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/ADT/TinyPtrVector.h"
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/CodeGen/LiveIntervalAnalysis.h"
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#include "llvm/CodeGen/LiveRangeEdit.h"
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#include "llvm/CodeGen/LiveStackAnalysis.h"
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#include "llvm/CodeGen/MachineDominators.h"
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#include "llvm/CodeGen/MachineInstrBundle.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineLoopInfo.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/TargetInstrInfo.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/raw_ostream.h"
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using namespace llvm;
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STATISTIC(NumSpilledRanges, "Number of spilled live ranges");
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STATISTIC(NumSnippets, "Number of spilled snippets");
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STATISTIC(NumSpills, "Number of spills inserted");
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STATISTIC(NumSpillsRemoved, "Number of spills removed");
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STATISTIC(NumReloads, "Number of reloads inserted");
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STATISTIC(NumReloadsRemoved, "Number of reloads removed");
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STATISTIC(NumFolded, "Number of folded stack accesses");
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STATISTIC(NumFoldedLoads, "Number of folded loads");
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STATISTIC(NumRemats, "Number of rematerialized defs for spilling");
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STATISTIC(NumOmitReloadSpill, "Number of omitted spills of reloads");
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STATISTIC(NumHoists, "Number of hoisted spills");
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static cl::opt<bool> DisableHoisting("disable-spill-hoist", cl::Hidden,
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cl::desc("Disable inline spill hoisting"));
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namespace {
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class InlineSpiller : public Spiller {
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MachineFunction &MF;
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LiveIntervals &LIS;
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LiveStacks &LSS;
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AliasAnalysis *AA;
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MachineDominatorTree &MDT;
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MachineLoopInfo &Loops;
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VirtRegMap &VRM;
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MachineFrameInfo &MFI;
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MachineRegisterInfo &MRI;
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const TargetInstrInfo &TII;
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const TargetRegisterInfo &TRI;
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// Variables that are valid during spill(), but used by multiple methods.
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LiveRangeEdit *Edit;
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LiveInterval *StackInt;
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int StackSlot;
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unsigned Original;
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// All registers to spill to StackSlot, including the main register.
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SmallVector<unsigned, 8> RegsToSpill;
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// All COPY instructions to/from snippets.
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// They are ignored since both operands refer to the same stack slot.
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SmallPtrSet<MachineInstr*, 8> SnippetCopies;
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// Values that failed to remat at some point.
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SmallPtrSet<VNInfo*, 8> UsedValues;
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public:
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// Information about a value that was defined by a copy from a sibling
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// register.
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struct SibValueInfo {
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// True when all reaching defs were reloads: No spill is necessary.
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bool AllDefsAreReloads;
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// True when value is defined by an original PHI not from splitting.
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bool DefByOrigPHI;
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// True when the COPY defining this value killed its source.
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bool KillsSource;
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// The preferred register to spill.
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unsigned SpillReg;
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// The value of SpillReg that should be spilled.
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VNInfo *SpillVNI;
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// The block where SpillVNI should be spilled. Currently, this must be the
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// block containing SpillVNI->def.
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MachineBasicBlock *SpillMBB;
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// A defining instruction that is not a sibling copy or a reload, or NULL.
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// This can be used as a template for rematerialization.
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MachineInstr *DefMI;
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// List of values that depend on this one. These values are actually the
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// same, but live range splitting has placed them in different registers,
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// or SSA update needed to insert PHI-defs to preserve SSA form. This is
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// copies of the current value and phi-kills. Usually only phi-kills cause
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// more than one dependent value.
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TinyPtrVector<VNInfo*> Deps;
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SibValueInfo(unsigned Reg, VNInfo *VNI)
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: AllDefsAreReloads(true), DefByOrigPHI(false), KillsSource(false),
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SpillReg(Reg), SpillVNI(VNI), SpillMBB(0), DefMI(0) {}
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// Returns true when a def has been found.
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bool hasDef() const { return DefByOrigPHI || DefMI; }
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};
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private:
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// Values in RegsToSpill defined by sibling copies.
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typedef DenseMap<VNInfo*, SibValueInfo> SibValueMap;
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SibValueMap SibValues;
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// Dead defs generated during spilling.
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SmallVector<MachineInstr*, 8> DeadDefs;
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~InlineSpiller() {}
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public:
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InlineSpiller(MachineFunctionPass &pass,
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MachineFunction &mf,
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VirtRegMap &vrm)
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: MF(mf),
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LIS(pass.getAnalysis<LiveIntervals>()),
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LSS(pass.getAnalysis<LiveStacks>()),
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AA(&pass.getAnalysis<AliasAnalysis>()),
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MDT(pass.getAnalysis<MachineDominatorTree>()),
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Loops(pass.getAnalysis<MachineLoopInfo>()),
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VRM(vrm),
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MFI(*mf.getFrameInfo()),
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MRI(mf.getRegInfo()),
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TII(*mf.getTarget().getInstrInfo()),
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TRI(*mf.getTarget().getRegisterInfo()) {}
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void spill(LiveRangeEdit &);
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private:
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bool isSnippet(const LiveInterval &SnipLI);
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void collectRegsToSpill();
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bool isRegToSpill(unsigned Reg) {
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return std::find(RegsToSpill.begin(),
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RegsToSpill.end(), Reg) != RegsToSpill.end();
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}
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bool isSibling(unsigned Reg);
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MachineInstr *traceSiblingValue(unsigned, VNInfo*, VNInfo*);
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void propagateSiblingValue(SibValueMap::iterator, VNInfo *VNI = 0);
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void analyzeSiblingValues();
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bool hoistSpill(LiveInterval &SpillLI, MachineInstr *CopyMI);
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void eliminateRedundantSpills(LiveInterval &LI, VNInfo *VNI);
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void markValueUsed(LiveInterval*, VNInfo*);
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bool reMaterializeFor(LiveInterval&, MachineBasicBlock::iterator MI);
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void reMaterializeAll();
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bool coalesceStackAccess(MachineInstr *MI, unsigned Reg);
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bool foldMemoryOperand(ArrayRef<std::pair<MachineInstr*, unsigned> >,
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MachineInstr *LoadMI = 0);
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void insertReload(LiveInterval &NewLI, SlotIndex,
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MachineBasicBlock::iterator MI);
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void insertSpill(LiveInterval &NewLI, const LiveInterval &OldLI,
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SlotIndex, MachineBasicBlock::iterator MI);
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void spillAroundUses(unsigned Reg);
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void spillAll();
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};
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}
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namespace llvm {
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Spiller *createInlineSpiller(MachineFunctionPass &pass,
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MachineFunction &mf,
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VirtRegMap &vrm) {
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return new InlineSpiller(pass, mf, vrm);
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}
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}
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//===----------------------------------------------------------------------===//
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// Snippets
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//===----------------------------------------------------------------------===//
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// When spilling a virtual register, we also spill any snippets it is connected
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// to. The snippets are small live ranges that only have a single real use,
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// leftovers from live range splitting. Spilling them enables memory operand
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// folding or tightens the live range around the single use.
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//
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// This minimizes register pressure and maximizes the store-to-load distance for
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// spill slots which can be important in tight loops.
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/// isFullCopyOf - If MI is a COPY to or from Reg, return the other register,
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/// otherwise return 0.
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static unsigned isFullCopyOf(const MachineInstr *MI, unsigned Reg) {
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if (!MI->isFullCopy())
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return 0;
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if (MI->getOperand(0).getReg() == Reg)
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return MI->getOperand(1).getReg();
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if (MI->getOperand(1).getReg() == Reg)
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return MI->getOperand(0).getReg();
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return 0;
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}
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/// isSnippet - Identify if a live interval is a snippet that should be spilled.
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/// It is assumed that SnipLI is a virtual register with the same original as
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/// Edit->getReg().
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bool InlineSpiller::isSnippet(const LiveInterval &SnipLI) {
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unsigned Reg = Edit->getReg();
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// A snippet is a tiny live range with only a single instruction using it
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// besides copies to/from Reg or spills/fills. We accept:
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//
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// %snip = COPY %Reg / FILL fi#
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// %snip = USE %snip
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// %Reg = COPY %snip / SPILL %snip, fi#
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//
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if (SnipLI.getNumValNums() > 2 || !LIS.intervalIsInOneMBB(SnipLI))
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return false;
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MachineInstr *UseMI = 0;
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// Check that all uses satisfy our criteria.
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for (MachineRegisterInfo::reg_nodbg_iterator
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RI = MRI.reg_nodbg_begin(SnipLI.reg);
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MachineInstr *MI = RI.skipInstruction();) {
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// Allow copies to/from Reg.
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if (isFullCopyOf(MI, Reg))
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continue;
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// Allow stack slot loads.
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int FI;
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if (SnipLI.reg == TII.isLoadFromStackSlot(MI, FI) && FI == StackSlot)
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continue;
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// Allow stack slot stores.
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if (SnipLI.reg == TII.isStoreToStackSlot(MI, FI) && FI == StackSlot)
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continue;
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// Allow a single additional instruction.
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if (UseMI && MI != UseMI)
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return false;
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UseMI = MI;
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}
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return true;
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}
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/// collectRegsToSpill - Collect live range snippets that only have a single
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/// real use.
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void InlineSpiller::collectRegsToSpill() {
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unsigned Reg = Edit->getReg();
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// Main register always spills.
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RegsToSpill.assign(1, Reg);
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SnippetCopies.clear();
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// Snippets all have the same original, so there can't be any for an original
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// register.
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if (Original == Reg)
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return;
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for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(Reg);
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MachineInstr *MI = RI.skipInstruction();) {
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unsigned SnipReg = isFullCopyOf(MI, Reg);
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if (!isSibling(SnipReg))
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continue;
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LiveInterval &SnipLI = LIS.getInterval(SnipReg);
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if (!isSnippet(SnipLI))
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continue;
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SnippetCopies.insert(MI);
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if (isRegToSpill(SnipReg))
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continue;
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RegsToSpill.push_back(SnipReg);
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DEBUG(dbgs() << "\talso spill snippet " << SnipLI << '\n');
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++NumSnippets;
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}
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}
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//===----------------------------------------------------------------------===//
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// Sibling Values
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//===----------------------------------------------------------------------===//
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// After live range splitting, some values to be spilled may be defined by
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// copies from sibling registers. We trace the sibling copies back to the
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// original value if it still exists. We need it for rematerialization.
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//
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// Even when the value can't be rematerialized, we still want to determine if
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// the value has already been spilled, or we may want to hoist the spill from a
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// loop.
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bool InlineSpiller::isSibling(unsigned Reg) {
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return TargetRegisterInfo::isVirtualRegister(Reg) &&
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VRM.getOriginal(Reg) == Original;
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}
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#ifndef NDEBUG
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static raw_ostream &operator<<(raw_ostream &OS,
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const InlineSpiller::SibValueInfo &SVI) {
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OS << "spill " << PrintReg(SVI.SpillReg) << ':'
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<< SVI.SpillVNI->id << '@' << SVI.SpillVNI->def;
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if (SVI.SpillMBB)
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OS << " in BB#" << SVI.SpillMBB->getNumber();
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if (SVI.AllDefsAreReloads)
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OS << " all-reloads";
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if (SVI.DefByOrigPHI)
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OS << " orig-phi";
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if (SVI.KillsSource)
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OS << " kill";
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OS << " deps[";
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for (unsigned i = 0, e = SVI.Deps.size(); i != e; ++i)
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OS << ' ' << SVI.Deps[i]->id << '@' << SVI.Deps[i]->def;
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OS << " ]";
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if (SVI.DefMI)
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OS << " def: " << *SVI.DefMI;
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else
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OS << '\n';
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return OS;
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}
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#endif
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/// propagateSiblingValue - Propagate the value in SVI to dependents if it is
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/// known. Otherwise remember the dependency for later.
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///
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/// @param SVI SibValues entry to propagate.
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/// @param VNI Dependent value, or NULL to propagate to all saved dependents.
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void InlineSpiller::propagateSiblingValue(SibValueMap::iterator SVI,
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VNInfo *VNI) {
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// When VNI is non-NULL, add it to SVI's deps, and only propagate to that.
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TinyPtrVector<VNInfo*> FirstDeps;
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if (VNI) {
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FirstDeps.push_back(VNI);
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SVI->second.Deps.push_back(VNI);
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}
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// Has the value been completely determined yet? If not, defer propagation.
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if (!SVI->second.hasDef())
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return;
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// Work list of values to propagate. It would be nice to use a SetVector
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// here, but then we would be forced to use a SmallSet.
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SmallVector<SibValueMap::iterator, 8> WorkList(1, SVI);
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SmallPtrSet<VNInfo*, 8> WorkSet;
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do {
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SVI = WorkList.pop_back_val();
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WorkSet.erase(SVI->first);
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TinyPtrVector<VNInfo*> *Deps = VNI ? &FirstDeps : &SVI->second.Deps;
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VNI = 0;
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SibValueInfo &SV = SVI->second;
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if (!SV.SpillMBB)
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SV.SpillMBB = LIS.getMBBFromIndex(SV.SpillVNI->def);
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DEBUG(dbgs() << " prop to " << Deps->size() << ": "
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<< SVI->first->id << '@' << SVI->first->def << ":\t" << SV);
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assert(SV.hasDef() && "Propagating undefined value");
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// Should this value be propagated as a preferred spill candidate? We don't
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// propagate values of registers that are about to spill.
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bool PropSpill = !DisableHoisting && !isRegToSpill(SV.SpillReg);
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unsigned SpillDepth = ~0u;
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for (TinyPtrVector<VNInfo*>::iterator DepI = Deps->begin(),
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DepE = Deps->end(); DepI != DepE; ++DepI) {
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SibValueMap::iterator DepSVI = SibValues.find(*DepI);
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assert(DepSVI != SibValues.end() && "Dependent value not in SibValues");
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SibValueInfo &DepSV = DepSVI->second;
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if (!DepSV.SpillMBB)
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DepSV.SpillMBB = LIS.getMBBFromIndex(DepSV.SpillVNI->def);
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bool Changed = false;
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// Propagate defining instruction.
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if (!DepSV.hasDef()) {
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Changed = true;
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DepSV.DefMI = SV.DefMI;
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DepSV.DefByOrigPHI = SV.DefByOrigPHI;
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}
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// Propagate AllDefsAreReloads. For PHI values, this computes an AND of
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// all predecessors.
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if (!SV.AllDefsAreReloads && DepSV.AllDefsAreReloads) {
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Changed = true;
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DepSV.AllDefsAreReloads = false;
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}
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// Propagate best spill value.
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if (PropSpill && SV.SpillVNI != DepSV.SpillVNI) {
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if (SV.SpillMBB == DepSV.SpillMBB) {
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// DepSV is in the same block. Hoist when dominated.
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if (DepSV.KillsSource && SV.SpillVNI->def < DepSV.SpillVNI->def) {
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// This is an alternative def earlier in the same MBB.
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// Hoist the spill as far as possible in SpillMBB. This can ease
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// register pressure:
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//
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// x = def
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// y = use x
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// s = copy x
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//
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// Hoisting the spill of s to immediately after the def removes the
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// interference between x and y:
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//
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// x = def
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// spill x
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// y = use x<kill>
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//
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// This hoist only helps when the DepSV copy kills its source.
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Changed = true;
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DepSV.SpillReg = SV.SpillReg;
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DepSV.SpillVNI = SV.SpillVNI;
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DepSV.SpillMBB = SV.SpillMBB;
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}
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} else {
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// DepSV is in a different block.
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if (SpillDepth == ~0u)
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SpillDepth = Loops.getLoopDepth(SV.SpillMBB);
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// Also hoist spills to blocks with smaller loop depth, but make sure
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// that the new value dominates. Non-phi dependents are always
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// dominated, phis need checking.
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if ((Loops.getLoopDepth(DepSV.SpillMBB) > SpillDepth) &&
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(!DepSVI->first->isPHIDef() ||
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MDT.dominates(SV.SpillMBB, DepSV.SpillMBB))) {
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Changed = true;
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DepSV.SpillReg = SV.SpillReg;
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DepSV.SpillVNI = SV.SpillVNI;
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DepSV.SpillMBB = SV.SpillMBB;
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}
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}
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}
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if (!Changed)
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continue;
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// Something changed in DepSVI. Propagate to dependents.
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if (WorkSet.insert(DepSVI->first))
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WorkList.push_back(DepSVI);
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DEBUG(dbgs() << " update " << DepSVI->first->id << '@'
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<< DepSVI->first->def << " to:\t" << DepSV);
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}
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} while (!WorkList.empty());
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}
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/// traceSiblingValue - Trace a value that is about to be spilled back to the
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/// real defining instructions by looking through sibling copies. Always stay
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/// within the range of OrigVNI so the registers are known to carry the same
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/// value.
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///
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/// Determine if the value is defined by all reloads, so spilling isn't
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/// necessary - the value is already in the stack slot.
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///
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/// Return a defining instruction that may be a candidate for rematerialization.
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///
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MachineInstr *InlineSpiller::traceSiblingValue(unsigned UseReg, VNInfo *UseVNI,
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VNInfo *OrigVNI) {
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// Check if a cached value already exists.
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SibValueMap::iterator SVI;
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bool Inserted;
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tie(SVI, Inserted) =
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SibValues.insert(std::make_pair(UseVNI, SibValueInfo(UseReg, UseVNI)));
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if (!Inserted) {
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DEBUG(dbgs() << "Cached value " << PrintReg(UseReg) << ':'
|
|
<< UseVNI->id << '@' << UseVNI->def << ' ' << SVI->second);
|
|
return SVI->second.DefMI;
|
|
}
|
|
|
|
DEBUG(dbgs() << "Tracing value " << PrintReg(UseReg) << ':'
|
|
<< UseVNI->id << '@' << UseVNI->def << '\n');
|
|
|
|
// List of (Reg, VNI) that have been inserted into SibValues, but need to be
|
|
// processed.
|
|
SmallVector<std::pair<unsigned, VNInfo*>, 8> WorkList;
|
|
WorkList.push_back(std::make_pair(UseReg, UseVNI));
|
|
|
|
do {
|
|
unsigned Reg;
|
|
VNInfo *VNI;
|
|
tie(Reg, VNI) = WorkList.pop_back_val();
|
|
DEBUG(dbgs() << " " << PrintReg(Reg) << ':' << VNI->id << '@' << VNI->def
|
|
<< ":\t");
|
|
|
|
// First check if this value has already been computed.
|
|
SVI = SibValues.find(VNI);
|
|
assert(SVI != SibValues.end() && "Missing SibValues entry");
|
|
|
|
// Trace through PHI-defs created by live range splitting.
|
|
if (VNI->isPHIDef()) {
|
|
// Stop at original PHIs. We don't know the value at the predecessors.
|
|
if (VNI->def == OrigVNI->def) {
|
|
DEBUG(dbgs() << "orig phi value\n");
|
|
SVI->second.DefByOrigPHI = true;
|
|
SVI->second.AllDefsAreReloads = false;
|
|
propagateSiblingValue(SVI);
|
|
continue;
|
|
}
|
|
|
|
// This is a PHI inserted by live range splitting. We could trace the
|
|
// live-out value from predecessor blocks, but that search can be very
|
|
// expensive if there are many predecessors and many more PHIs as
|
|
// generated by tail-dup when it sees an indirectbr. Instead, look at
|
|
// all the non-PHI defs that have the same value as OrigVNI. They must
|
|
// jointly dominate VNI->def. This is not optimal since VNI may actually
|
|
// be jointly dominated by a smaller subset of defs, so there is a change
|
|
// we will miss a AllDefsAreReloads optimization.
|
|
|
|
// Separate all values dominated by OrigVNI into PHIs and non-PHIs.
|
|
SmallVector<VNInfo*, 8> PHIs, NonPHIs;
|
|
LiveInterval &LI = LIS.getInterval(Reg);
|
|
LiveInterval &OrigLI = LIS.getInterval(Original);
|
|
|
|
for (LiveInterval::vni_iterator VI = LI.vni_begin(), VE = LI.vni_end();
|
|
VI != VE; ++VI) {
|
|
VNInfo *VNI2 = *VI;
|
|
if (VNI2->isUnused())
|
|
continue;
|
|
if (!OrigLI.containsOneValue() &&
|
|
OrigLI.getVNInfoAt(VNI2->def) != OrigVNI)
|
|
continue;
|
|
if (VNI2->isPHIDef() && VNI2->def != OrigVNI->def)
|
|
PHIs.push_back(VNI2);
|
|
else
|
|
NonPHIs.push_back(VNI2);
|
|
}
|
|
DEBUG(dbgs() << "split phi value, checking " << PHIs.size()
|
|
<< " phi-defs, and " << NonPHIs.size()
|
|
<< " non-phi/orig defs\n");
|
|
|
|
// Create entries for all the PHIs. Don't add them to the worklist, we
|
|
// are processing all of them in one go here.
|
|
for (unsigned i = 0, e = PHIs.size(); i != e; ++i)
|
|
SibValues.insert(std::make_pair(PHIs[i], SibValueInfo(Reg, PHIs[i])));
|
|
|
|
// Add every PHI as a dependent of all the non-PHIs.
|
|
for (unsigned i = 0, e = NonPHIs.size(); i != e; ++i) {
|
|
VNInfo *NonPHI = NonPHIs[i];
|
|
// Known value? Try an insertion.
|
|
tie(SVI, Inserted) =
|
|
SibValues.insert(std::make_pair(NonPHI, SibValueInfo(Reg, NonPHI)));
|
|
// Add all the PHIs as dependents of NonPHI.
|
|
for (unsigned pi = 0, pe = PHIs.size(); pi != pe; ++pi)
|
|
SVI->second.Deps.push_back(PHIs[pi]);
|
|
// This is the first time we see NonPHI, add it to the worklist.
|
|
if (Inserted)
|
|
WorkList.push_back(std::make_pair(Reg, NonPHI));
|
|
else
|
|
// Propagate to all inserted PHIs, not just VNI.
|
|
propagateSiblingValue(SVI);
|
|
}
|
|
|
|
// Next work list item.
|
|
continue;
|
|
}
|
|
|
|
MachineInstr *MI = LIS.getInstructionFromIndex(VNI->def);
|
|
assert(MI && "Missing def");
|
|
|
|
// Trace through sibling copies.
|
|
if (unsigned SrcReg = isFullCopyOf(MI, Reg)) {
|
|
if (isSibling(SrcReg)) {
|
|
LiveInterval &SrcLI = LIS.getInterval(SrcReg);
|
|
LiveRangeQuery SrcQ(SrcLI, VNI->def);
|
|
assert(SrcQ.valueIn() && "Copy from non-existing value");
|
|
// Check if this COPY kills its source.
|
|
SVI->second.KillsSource = SrcQ.isKill();
|
|
VNInfo *SrcVNI = SrcQ.valueIn();
|
|
DEBUG(dbgs() << "copy of " << PrintReg(SrcReg) << ':'
|
|
<< SrcVNI->id << '@' << SrcVNI->def
|
|
<< " kill=" << unsigned(SVI->second.KillsSource) << '\n');
|
|
// Known sibling source value? Try an insertion.
|
|
tie(SVI, Inserted) = SibValues.insert(std::make_pair(SrcVNI,
|
|
SibValueInfo(SrcReg, SrcVNI)));
|
|
// This is the first time we see Src, add it to the worklist.
|
|
if (Inserted)
|
|
WorkList.push_back(std::make_pair(SrcReg, SrcVNI));
|
|
propagateSiblingValue(SVI, VNI);
|
|
// Next work list item.
|
|
continue;
|
|
}
|
|
}
|
|
|
|
// Track reachable reloads.
|
|
SVI->second.DefMI = MI;
|
|
SVI->second.SpillMBB = MI->getParent();
|
|
int FI;
|
|
if (Reg == TII.isLoadFromStackSlot(MI, FI) && FI == StackSlot) {
|
|
DEBUG(dbgs() << "reload\n");
|
|
propagateSiblingValue(SVI);
|
|
// Next work list item.
|
|
continue;
|
|
}
|
|
|
|
// Potential remat candidate.
|
|
DEBUG(dbgs() << "def " << *MI);
|
|
SVI->second.AllDefsAreReloads = false;
|
|
propagateSiblingValue(SVI);
|
|
} while (!WorkList.empty());
|
|
|
|
// Look up the value we were looking for. We already did this lokup at the
|
|
// top of the function, but SibValues may have been invalidated.
|
|
SVI = SibValues.find(UseVNI);
|
|
assert(SVI != SibValues.end() && "Didn't compute requested info");
|
|
DEBUG(dbgs() << " traced to:\t" << SVI->second);
|
|
return SVI->second.DefMI;
|
|
}
|
|
|
|
/// analyzeSiblingValues - Trace values defined by sibling copies back to
|
|
/// something that isn't a sibling copy.
|
|
///
|
|
/// Keep track of values that may be rematerializable.
|
|
void InlineSpiller::analyzeSiblingValues() {
|
|
SibValues.clear();
|
|
|
|
// No siblings at all?
|
|
if (Edit->getReg() == Original)
|
|
return;
|
|
|
|
LiveInterval &OrigLI = LIS.getInterval(Original);
|
|
for (unsigned i = 0, e = RegsToSpill.size(); i != e; ++i) {
|
|
unsigned Reg = RegsToSpill[i];
|
|
LiveInterval &LI = LIS.getInterval(Reg);
|
|
for (LiveInterval::const_vni_iterator VI = LI.vni_begin(),
|
|
VE = LI.vni_end(); VI != VE; ++VI) {
|
|
VNInfo *VNI = *VI;
|
|
if (VNI->isUnused())
|
|
continue;
|
|
MachineInstr *DefMI = 0;
|
|
if (!VNI->isPHIDef()) {
|
|
DefMI = LIS.getInstructionFromIndex(VNI->def);
|
|
assert(DefMI && "No defining instruction");
|
|
}
|
|
// Check possible sibling copies.
|
|
if (VNI->isPHIDef() || DefMI->isCopy()) {
|
|
VNInfo *OrigVNI = OrigLI.getVNInfoAt(VNI->def);
|
|
assert(OrigVNI && "Def outside original live range");
|
|
if (OrigVNI->def != VNI->def)
|
|
DefMI = traceSiblingValue(Reg, VNI, OrigVNI);
|
|
}
|
|
if (DefMI && Edit->checkRematerializable(VNI, DefMI, AA)) {
|
|
DEBUG(dbgs() << "Value " << PrintReg(Reg) << ':' << VNI->id << '@'
|
|
<< VNI->def << " may remat from " << *DefMI);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// hoistSpill - Given a sibling copy that defines a value to be spilled, insert
|
|
/// a spill at a better location.
|
|
bool InlineSpiller::hoistSpill(LiveInterval &SpillLI, MachineInstr *CopyMI) {
|
|
SlotIndex Idx = LIS.getInstructionIndex(CopyMI);
|
|
VNInfo *VNI = SpillLI.getVNInfoAt(Idx.getRegSlot());
|
|
assert(VNI && VNI->def == Idx.getRegSlot() && "Not defined by copy");
|
|
SibValueMap::iterator I = SibValues.find(VNI);
|
|
if (I == SibValues.end())
|
|
return false;
|
|
|
|
const SibValueInfo &SVI = I->second;
|
|
|
|
// Let the normal folding code deal with the boring case.
|
|
if (!SVI.AllDefsAreReloads && SVI.SpillVNI == VNI)
|
|
return false;
|
|
|
|
// SpillReg may have been deleted by remat and DCE.
|
|
if (!LIS.hasInterval(SVI.SpillReg)) {
|
|
DEBUG(dbgs() << "Stale interval: " << PrintReg(SVI.SpillReg) << '\n');
|
|
SibValues.erase(I);
|
|
return false;
|
|
}
|
|
|
|
LiveInterval &SibLI = LIS.getInterval(SVI.SpillReg);
|
|
if (!SibLI.containsValue(SVI.SpillVNI)) {
|
|
DEBUG(dbgs() << "Stale value: " << PrintReg(SVI.SpillReg) << '\n');
|
|
SibValues.erase(I);
|
|
return false;
|
|
}
|
|
|
|
// Conservatively extend the stack slot range to the range of the original
|
|
// value. We may be able to do better with stack slot coloring by being more
|
|
// careful here.
|
|
assert(StackInt && "No stack slot assigned yet.");
|
|
LiveInterval &OrigLI = LIS.getInterval(Original);
|
|
VNInfo *OrigVNI = OrigLI.getVNInfoAt(Idx);
|
|
StackInt->MergeValueInAsValue(OrigLI, OrigVNI, StackInt->getValNumInfo(0));
|
|
DEBUG(dbgs() << "\tmerged orig valno " << OrigVNI->id << ": "
|
|
<< *StackInt << '\n');
|
|
|
|
// Already spilled everywhere.
|
|
if (SVI.AllDefsAreReloads) {
|
|
DEBUG(dbgs() << "\tno spill needed: " << SVI);
|
|
++NumOmitReloadSpill;
|
|
return true;
|
|
}
|
|
// We are going to spill SVI.SpillVNI immediately after its def, so clear out
|
|
// any later spills of the same value.
|
|
eliminateRedundantSpills(SibLI, SVI.SpillVNI);
|
|
|
|
MachineBasicBlock *MBB = LIS.getMBBFromIndex(SVI.SpillVNI->def);
|
|
MachineBasicBlock::iterator MII;
|
|
if (SVI.SpillVNI->isPHIDef())
|
|
MII = MBB->SkipPHIsAndLabels(MBB->begin());
|
|
else {
|
|
MachineInstr *DefMI = LIS.getInstructionFromIndex(SVI.SpillVNI->def);
|
|
assert(DefMI && "Defining instruction disappeared");
|
|
MII = DefMI;
|
|
++MII;
|
|
}
|
|
// Insert spill without kill flag immediately after def.
|
|
TII.storeRegToStackSlot(*MBB, MII, SVI.SpillReg, false, StackSlot,
|
|
MRI.getRegClass(SVI.SpillReg), &TRI);
|
|
--MII; // Point to store instruction.
|
|
LIS.InsertMachineInstrInMaps(MII);
|
|
DEBUG(dbgs() << "\thoisted: " << SVI.SpillVNI->def << '\t' << *MII);
|
|
|
|
++NumSpills;
|
|
++NumHoists;
|
|
return true;
|
|
}
|
|
|
|
/// eliminateRedundantSpills - SLI:VNI is known to be on the stack. Remove any
|
|
/// redundant spills of this value in SLI.reg and sibling copies.
|
|
void InlineSpiller::eliminateRedundantSpills(LiveInterval &SLI, VNInfo *VNI) {
|
|
assert(VNI && "Missing value");
|
|
SmallVector<std::pair<LiveInterval*, VNInfo*>, 8> WorkList;
|
|
WorkList.push_back(std::make_pair(&SLI, VNI));
|
|
assert(StackInt && "No stack slot assigned yet.");
|
|
|
|
do {
|
|
LiveInterval *LI;
|
|
tie(LI, VNI) = WorkList.pop_back_val();
|
|
unsigned Reg = LI->reg;
|
|
DEBUG(dbgs() << "Checking redundant spills for "
|
|
<< VNI->id << '@' << VNI->def << " in " << *LI << '\n');
|
|
|
|
// Regs to spill are taken care of.
|
|
if (isRegToSpill(Reg))
|
|
continue;
|
|
|
|
// Add all of VNI's live range to StackInt.
|
|
StackInt->MergeValueInAsValue(*LI, VNI, StackInt->getValNumInfo(0));
|
|
DEBUG(dbgs() << "Merged to stack int: " << *StackInt << '\n');
|
|
|
|
// Find all spills and copies of VNI.
|
|
for (MachineRegisterInfo::use_nodbg_iterator UI = MRI.use_nodbg_begin(Reg);
|
|
MachineInstr *MI = UI.skipInstruction();) {
|
|
if (!MI->isCopy() && !MI->mayStore())
|
|
continue;
|
|
SlotIndex Idx = LIS.getInstructionIndex(MI);
|
|
if (LI->getVNInfoAt(Idx) != VNI)
|
|
continue;
|
|
|
|
// Follow sibling copies down the dominator tree.
|
|
if (unsigned DstReg = isFullCopyOf(MI, Reg)) {
|
|
if (isSibling(DstReg)) {
|
|
LiveInterval &DstLI = LIS.getInterval(DstReg);
|
|
VNInfo *DstVNI = DstLI.getVNInfoAt(Idx.getRegSlot());
|
|
assert(DstVNI && "Missing defined value");
|
|
assert(DstVNI->def == Idx.getRegSlot() && "Wrong copy def slot");
|
|
WorkList.push_back(std::make_pair(&DstLI, DstVNI));
|
|
}
|
|
continue;
|
|
}
|
|
|
|
// Erase spills.
|
|
int FI;
|
|
if (Reg == TII.isStoreToStackSlot(MI, FI) && FI == StackSlot) {
|
|
DEBUG(dbgs() << "Redundant spill " << Idx << '\t' << *MI);
|
|
// eliminateDeadDefs won't normally remove stores, so switch opcode.
|
|
MI->setDesc(TII.get(TargetOpcode::KILL));
|
|
DeadDefs.push_back(MI);
|
|
++NumSpillsRemoved;
|
|
--NumSpills;
|
|
}
|
|
}
|
|
} while (!WorkList.empty());
|
|
}
|
|
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Rematerialization
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
/// markValueUsed - Remember that VNI failed to rematerialize, so its defining
|
|
/// instruction cannot be eliminated. See through snippet copies
|
|
void InlineSpiller::markValueUsed(LiveInterval *LI, VNInfo *VNI) {
|
|
SmallVector<std::pair<LiveInterval*, VNInfo*>, 8> WorkList;
|
|
WorkList.push_back(std::make_pair(LI, VNI));
|
|
do {
|
|
tie(LI, VNI) = WorkList.pop_back_val();
|
|
if (!UsedValues.insert(VNI))
|
|
continue;
|
|
|
|
if (VNI->isPHIDef()) {
|
|
MachineBasicBlock *MBB = LIS.getMBBFromIndex(VNI->def);
|
|
for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
|
|
PE = MBB->pred_end(); PI != PE; ++PI) {
|
|
VNInfo *PVNI = LI->getVNInfoBefore(LIS.getMBBEndIdx(*PI));
|
|
if (PVNI)
|
|
WorkList.push_back(std::make_pair(LI, PVNI));
|
|
}
|
|
continue;
|
|
}
|
|
|
|
// Follow snippet copies.
|
|
MachineInstr *MI = LIS.getInstructionFromIndex(VNI->def);
|
|
if (!SnippetCopies.count(MI))
|
|
continue;
|
|
LiveInterval &SnipLI = LIS.getInterval(MI->getOperand(1).getReg());
|
|
assert(isRegToSpill(SnipLI.reg) && "Unexpected register in copy");
|
|
VNInfo *SnipVNI = SnipLI.getVNInfoAt(VNI->def.getRegSlot(true));
|
|
assert(SnipVNI && "Snippet undefined before copy");
|
|
WorkList.push_back(std::make_pair(&SnipLI, SnipVNI));
|
|
} while (!WorkList.empty());
|
|
}
|
|
|
|
/// reMaterializeFor - Attempt to rematerialize before MI instead of reloading.
|
|
bool InlineSpiller::reMaterializeFor(LiveInterval &VirtReg,
|
|
MachineBasicBlock::iterator MI) {
|
|
SlotIndex UseIdx = LIS.getInstructionIndex(MI).getRegSlot(true);
|
|
VNInfo *ParentVNI = VirtReg.getVNInfoAt(UseIdx.getBaseIndex());
|
|
|
|
if (!ParentVNI) {
|
|
DEBUG(dbgs() << "\tadding <undef> flags: ");
|
|
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
if (MO.isReg() && MO.isUse() && MO.getReg() == VirtReg.reg)
|
|
MO.setIsUndef();
|
|
}
|
|
DEBUG(dbgs() << UseIdx << '\t' << *MI);
|
|
return true;
|
|
}
|
|
|
|
if (SnippetCopies.count(MI))
|
|
return false;
|
|
|
|
// Use an OrigVNI from traceSiblingValue when ParentVNI is a sibling copy.
|
|
LiveRangeEdit::Remat RM(ParentVNI);
|
|
SibValueMap::const_iterator SibI = SibValues.find(ParentVNI);
|
|
if (SibI != SibValues.end())
|
|
RM.OrigMI = SibI->second.DefMI;
|
|
if (!Edit->canRematerializeAt(RM, UseIdx, false)) {
|
|
markValueUsed(&VirtReg, ParentVNI);
|
|
DEBUG(dbgs() << "\tcannot remat for " << UseIdx << '\t' << *MI);
|
|
return false;
|
|
}
|
|
|
|
// If the instruction also writes VirtReg.reg, it had better not require the
|
|
// same register for uses and defs.
|
|
SmallVector<std::pair<MachineInstr*, unsigned>, 8> Ops;
|
|
MIBundleOperands::RegInfo RI =
|
|
MIBundleOperands(MI).analyzeVirtReg(VirtReg.reg, &Ops);
|
|
if (RI.Tied) {
|
|
markValueUsed(&VirtReg, ParentVNI);
|
|
DEBUG(dbgs() << "\tcannot remat tied reg: " << UseIdx << '\t' << *MI);
|
|
return false;
|
|
}
|
|
|
|
// Before rematerializing into a register for a single instruction, try to
|
|
// fold a load into the instruction. That avoids allocating a new register.
|
|
if (RM.OrigMI->canFoldAsLoad() &&
|
|
foldMemoryOperand(Ops, RM.OrigMI)) {
|
|
Edit->markRematerialized(RM.ParentVNI);
|
|
++NumFoldedLoads;
|
|
return true;
|
|
}
|
|
|
|
// Alocate a new register for the remat.
|
|
LiveInterval &NewLI = Edit->createFrom(Original);
|
|
NewLI.markNotSpillable();
|
|
|
|
// Finally we can rematerialize OrigMI before MI.
|
|
SlotIndex DefIdx = Edit->rematerializeAt(*MI->getParent(), MI, NewLI.reg, RM,
|
|
TRI);
|
|
DEBUG(dbgs() << "\tremat: " << DefIdx << '\t'
|
|
<< *LIS.getInstructionFromIndex(DefIdx));
|
|
|
|
// Replace operands
|
|
for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
|
|
MachineOperand &MO = MI->getOperand(Ops[i].second);
|
|
if (MO.isReg() && MO.isUse() && MO.getReg() == VirtReg.reg) {
|
|
MO.setReg(NewLI.reg);
|
|
MO.setIsKill();
|
|
}
|
|
}
|
|
DEBUG(dbgs() << "\t " << UseIdx << '\t' << *MI);
|
|
|
|
VNInfo *DefVNI = NewLI.getNextValue(DefIdx, LIS.getVNInfoAllocator());
|
|
NewLI.addRange(LiveRange(DefIdx, UseIdx.getRegSlot(), DefVNI));
|
|
DEBUG(dbgs() << "\tinterval: " << NewLI << '\n');
|
|
++NumRemats;
|
|
return true;
|
|
}
|
|
|
|
/// reMaterializeAll - Try to rematerialize as many uses as possible,
|
|
/// and trim the live ranges after.
|
|
void InlineSpiller::reMaterializeAll() {
|
|
// analyzeSiblingValues has already tested all relevant defining instructions.
|
|
if (!Edit->anyRematerializable(AA))
|
|
return;
|
|
|
|
UsedValues.clear();
|
|
|
|
// Try to remat before all uses of snippets.
|
|
bool anyRemat = false;
|
|
for (unsigned i = 0, e = RegsToSpill.size(); i != e; ++i) {
|
|
unsigned Reg = RegsToSpill[i];
|
|
LiveInterval &LI = LIS.getInterval(Reg);
|
|
for (MachineRegisterInfo::use_nodbg_iterator
|
|
RI = MRI.use_nodbg_begin(Reg);
|
|
MachineInstr *MI = RI.skipBundle();)
|
|
anyRemat |= reMaterializeFor(LI, MI);
|
|
}
|
|
if (!anyRemat)
|
|
return;
|
|
|
|
// Remove any values that were completely rematted.
|
|
for (unsigned i = 0, e = RegsToSpill.size(); i != e; ++i) {
|
|
unsigned Reg = RegsToSpill[i];
|
|
LiveInterval &LI = LIS.getInterval(Reg);
|
|
for (LiveInterval::vni_iterator I = LI.vni_begin(), E = LI.vni_end();
|
|
I != E; ++I) {
|
|
VNInfo *VNI = *I;
|
|
if (VNI->isUnused() || VNI->isPHIDef() || UsedValues.count(VNI))
|
|
continue;
|
|
MachineInstr *MI = LIS.getInstructionFromIndex(VNI->def);
|
|
MI->addRegisterDead(Reg, &TRI);
|
|
if (!MI->allDefsAreDead())
|
|
continue;
|
|
DEBUG(dbgs() << "All defs dead: " << *MI);
|
|
DeadDefs.push_back(MI);
|
|
}
|
|
}
|
|
|
|
// Eliminate dead code after remat. Note that some snippet copies may be
|
|
// deleted here.
|
|
if (DeadDefs.empty())
|
|
return;
|
|
DEBUG(dbgs() << "Remat created " << DeadDefs.size() << " dead defs.\n");
|
|
Edit->eliminateDeadDefs(DeadDefs, RegsToSpill);
|
|
|
|
// Get rid of deleted and empty intervals.
|
|
for (unsigned i = RegsToSpill.size(); i != 0; --i) {
|
|
unsigned Reg = RegsToSpill[i-1];
|
|
if (!LIS.hasInterval(Reg)) {
|
|
RegsToSpill.erase(RegsToSpill.begin() + (i - 1));
|
|
continue;
|
|
}
|
|
LiveInterval &LI = LIS.getInterval(Reg);
|
|
if (!LI.empty())
|
|
continue;
|
|
Edit->eraseVirtReg(Reg);
|
|
RegsToSpill.erase(RegsToSpill.begin() + (i - 1));
|
|
}
|
|
DEBUG(dbgs() << RegsToSpill.size() << " registers to spill after remat.\n");
|
|
}
|
|
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Spilling
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
/// If MI is a load or store of StackSlot, it can be removed.
|
|
bool InlineSpiller::coalesceStackAccess(MachineInstr *MI, unsigned Reg) {
|
|
int FI = 0;
|
|
unsigned InstrReg = TII.isLoadFromStackSlot(MI, FI);
|
|
bool IsLoad = InstrReg;
|
|
if (!IsLoad)
|
|
InstrReg = TII.isStoreToStackSlot(MI, FI);
|
|
|
|
// We have a stack access. Is it the right register and slot?
|
|
if (InstrReg != Reg || FI != StackSlot)
|
|
return false;
|
|
|
|
DEBUG(dbgs() << "Coalescing stack access: " << *MI);
|
|
LIS.RemoveMachineInstrFromMaps(MI);
|
|
MI->eraseFromParent();
|
|
|
|
if (IsLoad) {
|
|
++NumReloadsRemoved;
|
|
--NumReloads;
|
|
} else {
|
|
++NumSpillsRemoved;
|
|
--NumSpills;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/// foldMemoryOperand - Try folding stack slot references in Ops into their
|
|
/// instructions.
|
|
///
|
|
/// @param Ops Operand indices from analyzeVirtReg().
|
|
/// @param LoadMI Load instruction to use instead of stack slot when non-null.
|
|
/// @return True on success.
|
|
bool InlineSpiller::
|
|
foldMemoryOperand(ArrayRef<std::pair<MachineInstr*, unsigned> > Ops,
|
|
MachineInstr *LoadMI) {
|
|
if (Ops.empty())
|
|
return false;
|
|
// Don't attempt folding in bundles.
|
|
MachineInstr *MI = Ops.front().first;
|
|
if (Ops.back().first != MI || MI->isBundled())
|
|
return false;
|
|
|
|
bool WasCopy = MI->isCopy();
|
|
unsigned ImpReg = 0;
|
|
|
|
// TargetInstrInfo::foldMemoryOperand only expects explicit, non-tied
|
|
// operands.
|
|
SmallVector<unsigned, 8> FoldOps;
|
|
for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
|
|
unsigned Idx = Ops[i].second;
|
|
MachineOperand &MO = MI->getOperand(Idx);
|
|
if (MO.isImplicit()) {
|
|
ImpReg = MO.getReg();
|
|
continue;
|
|
}
|
|
// FIXME: Teach targets to deal with subregs.
|
|
if (MO.getSubReg())
|
|
return false;
|
|
// We cannot fold a load instruction into a def.
|
|
if (LoadMI && MO.isDef())
|
|
return false;
|
|
// Tied use operands should not be passed to foldMemoryOperand.
|
|
if (!MI->isRegTiedToDefOperand(Idx))
|
|
FoldOps.push_back(Idx);
|
|
}
|
|
|
|
MachineInstr *FoldMI =
|
|
LoadMI ? TII.foldMemoryOperand(MI, FoldOps, LoadMI)
|
|
: TII.foldMemoryOperand(MI, FoldOps, StackSlot);
|
|
if (!FoldMI)
|
|
return false;
|
|
LIS.ReplaceMachineInstrInMaps(MI, FoldMI);
|
|
MI->eraseFromParent();
|
|
|
|
// TII.foldMemoryOperand may have left some implicit operands on the
|
|
// instruction. Strip them.
|
|
if (ImpReg)
|
|
for (unsigned i = FoldMI->getNumOperands(); i; --i) {
|
|
MachineOperand &MO = FoldMI->getOperand(i - 1);
|
|
if (!MO.isReg() || !MO.isImplicit())
|
|
break;
|
|
if (MO.getReg() == ImpReg)
|
|
FoldMI->RemoveOperand(i - 1);
|
|
}
|
|
|
|
DEBUG(dbgs() << "\tfolded: " << LIS.getInstructionIndex(FoldMI) << '\t'
|
|
<< *FoldMI);
|
|
if (!WasCopy)
|
|
++NumFolded;
|
|
else if (Ops.front().second == 0)
|
|
++NumSpills;
|
|
else
|
|
++NumReloads;
|
|
return true;
|
|
}
|
|
|
|
/// insertReload - Insert a reload of NewLI.reg before MI.
|
|
void InlineSpiller::insertReload(LiveInterval &NewLI,
|
|
SlotIndex Idx,
|
|
MachineBasicBlock::iterator MI) {
|
|
MachineBasicBlock &MBB = *MI->getParent();
|
|
TII.loadRegFromStackSlot(MBB, MI, NewLI.reg, StackSlot,
|
|
MRI.getRegClass(NewLI.reg), &TRI);
|
|
--MI; // Point to load instruction.
|
|
SlotIndex LoadIdx = LIS.InsertMachineInstrInMaps(MI).getRegSlot();
|
|
DEBUG(dbgs() << "\treload: " << LoadIdx << '\t' << *MI);
|
|
VNInfo *LoadVNI = NewLI.getNextValue(LoadIdx, LIS.getVNInfoAllocator());
|
|
NewLI.addRange(LiveRange(LoadIdx, Idx, LoadVNI));
|
|
++NumReloads;
|
|
}
|
|
|
|
/// insertSpill - Insert a spill of NewLI.reg after MI.
|
|
void InlineSpiller::insertSpill(LiveInterval &NewLI, const LiveInterval &OldLI,
|
|
SlotIndex Idx, MachineBasicBlock::iterator MI) {
|
|
MachineBasicBlock &MBB = *MI->getParent();
|
|
TII.storeRegToStackSlot(MBB, ++MI, NewLI.reg, true, StackSlot,
|
|
MRI.getRegClass(NewLI.reg), &TRI);
|
|
--MI; // Point to store instruction.
|
|
SlotIndex StoreIdx = LIS.InsertMachineInstrInMaps(MI).getRegSlot();
|
|
DEBUG(dbgs() << "\tspilled: " << StoreIdx << '\t' << *MI);
|
|
VNInfo *StoreVNI = NewLI.getNextValue(Idx, LIS.getVNInfoAllocator());
|
|
NewLI.addRange(LiveRange(Idx, StoreIdx, StoreVNI));
|
|
++NumSpills;
|
|
}
|
|
|
|
/// spillAroundUses - insert spill code around each use of Reg.
|
|
void InlineSpiller::spillAroundUses(unsigned Reg) {
|
|
DEBUG(dbgs() << "spillAroundUses " << PrintReg(Reg) << '\n');
|
|
LiveInterval &OldLI = LIS.getInterval(Reg);
|
|
|
|
// Iterate over instructions using Reg.
|
|
for (MachineRegisterInfo::reg_iterator RegI = MRI.reg_begin(Reg);
|
|
MachineInstr *MI = RegI.skipBundle();) {
|
|
|
|
// Debug values are not allowed to affect codegen.
|
|
if (MI->isDebugValue()) {
|
|
// Modify DBG_VALUE now that the value is in a spill slot.
|
|
uint64_t Offset = MI->getOperand(1).getImm();
|
|
const MDNode *MDPtr = MI->getOperand(2).getMetadata();
|
|
DebugLoc DL = MI->getDebugLoc();
|
|
if (MachineInstr *NewDV = TII.emitFrameIndexDebugValue(MF, StackSlot,
|
|
Offset, MDPtr, DL)) {
|
|
DEBUG(dbgs() << "Modifying debug info due to spill:" << "\t" << *MI);
|
|
MachineBasicBlock *MBB = MI->getParent();
|
|
MBB->insert(MBB->erase(MI), NewDV);
|
|
} else {
|
|
DEBUG(dbgs() << "Removing debug info due to spill:" << "\t" << *MI);
|
|
MI->eraseFromParent();
|
|
}
|
|
continue;
|
|
}
|
|
|
|
// Ignore copies to/from snippets. We'll delete them.
|
|
if (SnippetCopies.count(MI))
|
|
continue;
|
|
|
|
// Stack slot accesses may coalesce away.
|
|
if (coalesceStackAccess(MI, Reg))
|
|
continue;
|
|
|
|
// Analyze instruction.
|
|
SmallVector<std::pair<MachineInstr*, unsigned>, 8> Ops;
|
|
MIBundleOperands::RegInfo RI =
|
|
MIBundleOperands(MI).analyzeVirtReg(Reg, &Ops);
|
|
|
|
// Find the slot index where this instruction reads and writes OldLI.
|
|
// This is usually the def slot, except for tied early clobbers.
|
|
SlotIndex Idx = LIS.getInstructionIndex(MI).getRegSlot();
|
|
if (VNInfo *VNI = OldLI.getVNInfoAt(Idx.getRegSlot(true)))
|
|
if (SlotIndex::isSameInstr(Idx, VNI->def))
|
|
Idx = VNI->def;
|
|
|
|
// Check for a sibling copy.
|
|
unsigned SibReg = isFullCopyOf(MI, Reg);
|
|
if (SibReg && isSibling(SibReg)) {
|
|
// This may actually be a copy between snippets.
|
|
if (isRegToSpill(SibReg)) {
|
|
DEBUG(dbgs() << "Found new snippet copy: " << *MI);
|
|
SnippetCopies.insert(MI);
|
|
continue;
|
|
}
|
|
if (RI.Writes) {
|
|
// Hoist the spill of a sib-reg copy.
|
|
if (hoistSpill(OldLI, MI)) {
|
|
// This COPY is now dead, the value is already in the stack slot.
|
|
MI->getOperand(0).setIsDead();
|
|
DeadDefs.push_back(MI);
|
|
continue;
|
|
}
|
|
} else {
|
|
// This is a reload for a sib-reg copy. Drop spills downstream.
|
|
LiveInterval &SibLI = LIS.getInterval(SibReg);
|
|
eliminateRedundantSpills(SibLI, SibLI.getVNInfoAt(Idx));
|
|
// The COPY will fold to a reload below.
|
|
}
|
|
}
|
|
|
|
// Attempt to fold memory ops.
|
|
if (foldMemoryOperand(Ops))
|
|
continue;
|
|
|
|
// Allocate interval around instruction.
|
|
// FIXME: Infer regclass from instruction alone.
|
|
LiveInterval &NewLI = Edit->createFrom(Reg);
|
|
NewLI.markNotSpillable();
|
|
|
|
if (RI.Reads)
|
|
insertReload(NewLI, Idx, MI);
|
|
|
|
// Rewrite instruction operands.
|
|
bool hasLiveDef = false;
|
|
for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
|
|
MachineOperand &MO = Ops[i].first->getOperand(Ops[i].second);
|
|
MO.setReg(NewLI.reg);
|
|
if (MO.isUse()) {
|
|
if (!Ops[i].first->isRegTiedToDefOperand(Ops[i].second))
|
|
MO.setIsKill();
|
|
} else {
|
|
if (!MO.isDead())
|
|
hasLiveDef = true;
|
|
}
|
|
}
|
|
DEBUG(dbgs() << "\trewrite: " << Idx << '\t' << *MI);
|
|
|
|
// FIXME: Use a second vreg if instruction has no tied ops.
|
|
if (RI.Writes) {
|
|
if (hasLiveDef)
|
|
insertSpill(NewLI, OldLI, Idx, MI);
|
|
else {
|
|
// This instruction defines a dead value. We don't need to spill it,
|
|
// but do create a live range for the dead value.
|
|
VNInfo *VNI = NewLI.getNextValue(Idx, LIS.getVNInfoAllocator());
|
|
NewLI.addRange(LiveRange(Idx, Idx.getDeadSlot(), VNI));
|
|
}
|
|
}
|
|
|
|
DEBUG(dbgs() << "\tinterval: " << NewLI << '\n');
|
|
}
|
|
}
|
|
|
|
/// spillAll - Spill all registers remaining after rematerialization.
|
|
void InlineSpiller::spillAll() {
|
|
// Update LiveStacks now that we are committed to spilling.
|
|
if (StackSlot == VirtRegMap::NO_STACK_SLOT) {
|
|
StackSlot = VRM.assignVirt2StackSlot(Original);
|
|
StackInt = &LSS.getOrCreateInterval(StackSlot, MRI.getRegClass(Original));
|
|
StackInt->getNextValue(SlotIndex(), LSS.getVNInfoAllocator());
|
|
} else
|
|
StackInt = &LSS.getInterval(StackSlot);
|
|
|
|
if (Original != Edit->getReg())
|
|
VRM.assignVirt2StackSlot(Edit->getReg(), StackSlot);
|
|
|
|
assert(StackInt->getNumValNums() == 1 && "Bad stack interval values");
|
|
for (unsigned i = 0, e = RegsToSpill.size(); i != e; ++i)
|
|
StackInt->MergeRangesInAsValue(LIS.getInterval(RegsToSpill[i]),
|
|
StackInt->getValNumInfo(0));
|
|
DEBUG(dbgs() << "Merged spilled regs: " << *StackInt << '\n');
|
|
|
|
// Spill around uses of all RegsToSpill.
|
|
for (unsigned i = 0, e = RegsToSpill.size(); i != e; ++i)
|
|
spillAroundUses(RegsToSpill[i]);
|
|
|
|
// Hoisted spills may cause dead code.
|
|
if (!DeadDefs.empty()) {
|
|
DEBUG(dbgs() << "Eliminating " << DeadDefs.size() << " dead defs\n");
|
|
Edit->eliminateDeadDefs(DeadDefs, RegsToSpill);
|
|
}
|
|
|
|
// Finally delete the SnippetCopies.
|
|
for (unsigned i = 0, e = RegsToSpill.size(); i != e; ++i) {
|
|
for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(RegsToSpill[i]);
|
|
MachineInstr *MI = RI.skipInstruction();) {
|
|
assert(SnippetCopies.count(MI) && "Remaining use wasn't a snippet copy");
|
|
// FIXME: Do this with a LiveRangeEdit callback.
|
|
LIS.RemoveMachineInstrFromMaps(MI);
|
|
MI->eraseFromParent();
|
|
}
|
|
}
|
|
|
|
// Delete all spilled registers.
|
|
for (unsigned i = 0, e = RegsToSpill.size(); i != e; ++i)
|
|
Edit->eraseVirtReg(RegsToSpill[i]);
|
|
}
|
|
|
|
void InlineSpiller::spill(LiveRangeEdit &edit) {
|
|
++NumSpilledRanges;
|
|
Edit = &edit;
|
|
assert(!TargetRegisterInfo::isStackSlot(edit.getReg())
|
|
&& "Trying to spill a stack slot.");
|
|
// Share a stack slot among all descendants of Original.
|
|
Original = VRM.getOriginal(edit.getReg());
|
|
StackSlot = VRM.getStackSlot(Original);
|
|
StackInt = 0;
|
|
|
|
DEBUG(dbgs() << "Inline spilling "
|
|
<< MRI.getRegClass(edit.getReg())->getName()
|
|
<< ':' << edit.getParent() << "\nFrom original "
|
|
<< LIS.getInterval(Original) << '\n');
|
|
assert(edit.getParent().isSpillable() &&
|
|
"Attempting to spill already spilled value.");
|
|
assert(DeadDefs.empty() && "Previous spill didn't remove dead defs");
|
|
|
|
collectRegsToSpill();
|
|
analyzeSiblingValues();
|
|
reMaterializeAll();
|
|
|
|
// Remat may handle everything.
|
|
if (!RegsToSpill.empty())
|
|
spillAll();
|
|
|
|
Edit->calculateRegClassAndHint(MF, Loops);
|
|
}
|