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1123 lines
42 KiB
1123 lines
42 KiB
//===-- RegAllocFast.cpp - A fast register allocator for debug code -------===//
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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 register allocator allocates registers to a basic block at a time,
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// attempting to keep values in registers and reusing registers as appropriate.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/IndexedMap.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/SmallSet.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/SparseSet.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineFunctionPass.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/MachineRegisterInfo.h"
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/CodeGen/RegAllocRegistry.h"
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#include "llvm/CodeGen/RegisterClassInfo.h"
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#include "llvm/IR/DebugInfo.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/Target/TargetInstrInfo.h"
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#include "llvm/Target/TargetSubtargetInfo.h"
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#include <algorithm>
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using namespace llvm;
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#define DEBUG_TYPE "regalloc"
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STATISTIC(NumStores, "Number of stores added");
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STATISTIC(NumLoads , "Number of loads added");
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STATISTIC(NumCopies, "Number of copies coalesced");
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static RegisterRegAlloc
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fastRegAlloc("fast", "fast register allocator", createFastRegisterAllocator);
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namespace {
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class RAFast : public MachineFunctionPass {
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public:
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static char ID;
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RAFast() : MachineFunctionPass(ID), StackSlotForVirtReg(-1),
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isBulkSpilling(false) {}
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private:
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MachineFunction *MF;
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MachineRegisterInfo *MRI;
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const TargetRegisterInfo *TRI;
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const TargetInstrInfo *TII;
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RegisterClassInfo RegClassInfo;
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// Basic block currently being allocated.
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MachineBasicBlock *MBB;
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// StackSlotForVirtReg - Maps virtual regs to the frame index where these
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// values are spilled.
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IndexedMap<int, VirtReg2IndexFunctor> StackSlotForVirtReg;
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// Everything we know about a live virtual register.
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struct LiveReg {
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MachineInstr *LastUse; // Last instr to use reg.
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unsigned VirtReg; // Virtual register number.
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unsigned PhysReg; // Currently held here.
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unsigned short LastOpNum; // OpNum on LastUse.
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bool Dirty; // Register needs spill.
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explicit LiveReg(unsigned v)
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: LastUse(nullptr), VirtReg(v), PhysReg(0), LastOpNum(0), Dirty(false){}
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unsigned getSparseSetIndex() const {
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return TargetRegisterInfo::virtReg2Index(VirtReg);
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}
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};
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typedef SparseSet<LiveReg> LiveRegMap;
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// LiveVirtRegs - This map contains entries for each virtual register
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// that is currently available in a physical register.
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LiveRegMap LiveVirtRegs;
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DenseMap<unsigned, SmallVector<MachineInstr *, 4> > LiveDbgValueMap;
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// RegState - Track the state of a physical register.
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enum RegState {
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// A disabled register is not available for allocation, but an alias may
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// be in use. A register can only be moved out of the disabled state if
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// all aliases are disabled.
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regDisabled,
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// A free register is not currently in use and can be allocated
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// immediately without checking aliases.
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regFree,
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// A reserved register has been assigned explicitly (e.g., setting up a
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// call parameter), and it remains reserved until it is used.
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regReserved
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// A register state may also be a virtual register number, indication that
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// the physical register is currently allocated to a virtual register. In
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// that case, LiveVirtRegs contains the inverse mapping.
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};
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// PhysRegState - One of the RegState enums, or a virtreg.
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std::vector<unsigned> PhysRegState;
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// Set of register units.
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typedef SparseSet<unsigned> UsedInInstrSet;
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// Set of register units that are used in the current instruction, and so
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// cannot be allocated.
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UsedInInstrSet UsedInInstr;
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// Mark a physreg as used in this instruction.
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void markRegUsedInInstr(unsigned PhysReg) {
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for (MCRegUnitIterator Units(PhysReg, TRI); Units.isValid(); ++Units)
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UsedInInstr.insert(*Units);
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}
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// Check if a physreg or any of its aliases are used in this instruction.
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bool isRegUsedInInstr(unsigned PhysReg) const {
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for (MCRegUnitIterator Units(PhysReg, TRI); Units.isValid(); ++Units)
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if (UsedInInstr.count(*Units))
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return true;
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return false;
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}
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// SkippedInstrs - Descriptors of instructions whose clobber list was
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// ignored because all registers were spilled. It is still necessary to
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// mark all the clobbered registers as used by the function.
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SmallPtrSet<const MCInstrDesc*, 4> SkippedInstrs;
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// isBulkSpilling - This flag is set when LiveRegMap will be cleared
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// completely after spilling all live registers. LiveRegMap entries should
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// not be erased.
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bool isBulkSpilling;
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enum : unsigned {
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spillClean = 1,
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spillDirty = 100,
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spillImpossible = ~0u
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};
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public:
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const char *getPassName() const override {
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return "Fast Register Allocator";
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}
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.setPreservesCFG();
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MachineFunctionPass::getAnalysisUsage(AU);
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}
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MachineFunctionProperties getSetProperties() const override {
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return MachineFunctionProperties().set(
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MachineFunctionProperties::Property::AllVRegsAllocated);
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}
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private:
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bool runOnMachineFunction(MachineFunction &Fn) override;
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void AllocateBasicBlock();
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void handleThroughOperands(MachineInstr *MI,
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SmallVectorImpl<unsigned> &VirtDead);
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int getStackSpaceFor(unsigned VirtReg, const TargetRegisterClass *RC);
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bool isLastUseOfLocalReg(MachineOperand&);
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void addKillFlag(const LiveReg&);
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void killVirtReg(LiveRegMap::iterator);
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void killVirtReg(unsigned VirtReg);
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void spillVirtReg(MachineBasicBlock::iterator MI, LiveRegMap::iterator);
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void spillVirtReg(MachineBasicBlock::iterator MI, unsigned VirtReg);
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void usePhysReg(MachineOperand&);
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void definePhysReg(MachineInstr &MI, unsigned PhysReg, RegState NewState);
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unsigned calcSpillCost(unsigned PhysReg) const;
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void assignVirtToPhysReg(LiveReg&, unsigned PhysReg);
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LiveRegMap::iterator findLiveVirtReg(unsigned VirtReg) {
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return LiveVirtRegs.find(TargetRegisterInfo::virtReg2Index(VirtReg));
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}
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LiveRegMap::const_iterator findLiveVirtReg(unsigned VirtReg) const {
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return LiveVirtRegs.find(TargetRegisterInfo::virtReg2Index(VirtReg));
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}
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LiveRegMap::iterator assignVirtToPhysReg(unsigned VReg, unsigned PhysReg);
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LiveRegMap::iterator allocVirtReg(MachineInstr &MI, LiveRegMap::iterator,
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unsigned Hint);
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LiveRegMap::iterator defineVirtReg(MachineInstr &MI, unsigned OpNum,
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unsigned VirtReg, unsigned Hint);
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LiveRegMap::iterator reloadVirtReg(MachineInstr &MI, unsigned OpNum,
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unsigned VirtReg, unsigned Hint);
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void spillAll(MachineBasicBlock::iterator MI);
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bool setPhysReg(MachineInstr *MI, unsigned OpNum, unsigned PhysReg);
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};
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char RAFast::ID = 0;
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}
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/// getStackSpaceFor - This allocates space for the specified virtual register
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/// to be held on the stack.
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int RAFast::getStackSpaceFor(unsigned VirtReg, const TargetRegisterClass *RC) {
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// Find the location Reg would belong...
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int SS = StackSlotForVirtReg[VirtReg];
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if (SS != -1)
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return SS; // Already has space allocated?
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// Allocate a new stack object for this spill location...
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int FrameIdx = MF->getFrameInfo()->CreateSpillStackObject(RC->getSize(),
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RC->getAlignment());
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// Assign the slot.
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StackSlotForVirtReg[VirtReg] = FrameIdx;
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return FrameIdx;
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}
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/// isLastUseOfLocalReg - Return true if MO is the only remaining reference to
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/// its virtual register, and it is guaranteed to be a block-local register.
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///
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bool RAFast::isLastUseOfLocalReg(MachineOperand &MO) {
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// If the register has ever been spilled or reloaded, we conservatively assume
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// it is a global register used in multiple blocks.
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if (StackSlotForVirtReg[MO.getReg()] != -1)
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return false;
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// Check that the use/def chain has exactly one operand - MO.
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MachineRegisterInfo::reg_nodbg_iterator I = MRI->reg_nodbg_begin(MO.getReg());
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if (&*I != &MO)
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return false;
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return ++I == MRI->reg_nodbg_end();
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}
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/// addKillFlag - Set kill flags on last use of a virtual register.
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void RAFast::addKillFlag(const LiveReg &LR) {
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if (!LR.LastUse) return;
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MachineOperand &MO = LR.LastUse->getOperand(LR.LastOpNum);
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if (MO.isUse() && !LR.LastUse->isRegTiedToDefOperand(LR.LastOpNum)) {
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if (MO.getReg() == LR.PhysReg)
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MO.setIsKill();
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else
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LR.LastUse->addRegisterKilled(LR.PhysReg, TRI, true);
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}
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}
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/// killVirtReg - Mark virtreg as no longer available.
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void RAFast::killVirtReg(LiveRegMap::iterator LRI) {
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addKillFlag(*LRI);
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assert(PhysRegState[LRI->PhysReg] == LRI->VirtReg &&
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"Broken RegState mapping");
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PhysRegState[LRI->PhysReg] = regFree;
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// Erase from LiveVirtRegs unless we're spilling in bulk.
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if (!isBulkSpilling)
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LiveVirtRegs.erase(LRI);
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}
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/// killVirtReg - Mark virtreg as no longer available.
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void RAFast::killVirtReg(unsigned VirtReg) {
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assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
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"killVirtReg needs a virtual register");
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LiveRegMap::iterator LRI = findLiveVirtReg(VirtReg);
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if (LRI != LiveVirtRegs.end())
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killVirtReg(LRI);
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}
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/// spillVirtReg - This method spills the value specified by VirtReg into the
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/// corresponding stack slot if needed.
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void RAFast::spillVirtReg(MachineBasicBlock::iterator MI, unsigned VirtReg) {
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assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
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"Spilling a physical register is illegal!");
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LiveRegMap::iterator LRI = findLiveVirtReg(VirtReg);
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assert(LRI != LiveVirtRegs.end() && "Spilling unmapped virtual register");
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spillVirtReg(MI, LRI);
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}
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/// spillVirtReg - Do the actual work of spilling.
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void RAFast::spillVirtReg(MachineBasicBlock::iterator MI,
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LiveRegMap::iterator LRI) {
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LiveReg &LR = *LRI;
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assert(PhysRegState[LR.PhysReg] == LRI->VirtReg && "Broken RegState mapping");
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if (LR.Dirty) {
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// If this physreg is used by the instruction, we want to kill it on the
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// instruction, not on the spill.
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bool SpillKill = MachineBasicBlock::iterator(LR.LastUse) != MI;
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LR.Dirty = false;
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DEBUG(dbgs() << "Spilling " << PrintReg(LRI->VirtReg, TRI)
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<< " in " << PrintReg(LR.PhysReg, TRI));
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const TargetRegisterClass *RC = MRI->getRegClass(LRI->VirtReg);
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int FI = getStackSpaceFor(LRI->VirtReg, RC);
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DEBUG(dbgs() << " to stack slot #" << FI << "\n");
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TII->storeRegToStackSlot(*MBB, MI, LR.PhysReg, SpillKill, FI, RC, TRI);
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++NumStores; // Update statistics
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// If this register is used by DBG_VALUE then insert new DBG_VALUE to
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// identify spilled location as the place to find corresponding variable's
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// value.
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SmallVectorImpl<MachineInstr *> &LRIDbgValues =
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LiveDbgValueMap[LRI->VirtReg];
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for (unsigned li = 0, le = LRIDbgValues.size(); li != le; ++li) {
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MachineInstr *DBG = LRIDbgValues[li];
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const MDNode *Var = DBG->getDebugVariable();
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const MDNode *Expr = DBG->getDebugExpression();
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bool IsIndirect = DBG->isIndirectDebugValue();
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uint64_t Offset = IsIndirect ? DBG->getOperand(1).getImm() : 0;
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DebugLoc DL = DBG->getDebugLoc();
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assert(cast<DILocalVariable>(Var)->isValidLocationForIntrinsic(DL) &&
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"Expected inlined-at fields to agree");
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MachineInstr *NewDV =
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BuildMI(*MBB, MI, DL, TII->get(TargetOpcode::DBG_VALUE))
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.addFrameIndex(FI)
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.addImm(Offset)
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.addMetadata(Var)
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.addMetadata(Expr);
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assert(NewDV->getParent() == MBB && "dangling parent pointer");
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(void)NewDV;
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DEBUG(dbgs() << "Inserting debug info due to spill:" << "\n" << *NewDV);
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}
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// Now this register is spilled there is should not be any DBG_VALUE
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// pointing to this register because they are all pointing to spilled value
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// now.
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LRIDbgValues.clear();
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if (SpillKill)
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LR.LastUse = nullptr; // Don't kill register again
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}
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killVirtReg(LRI);
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}
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/// spillAll - Spill all dirty virtregs without killing them.
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void RAFast::spillAll(MachineBasicBlock::iterator MI) {
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if (LiveVirtRegs.empty()) return;
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isBulkSpilling = true;
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// The LiveRegMap is keyed by an unsigned (the virtreg number), so the order
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// of spilling here is deterministic, if arbitrary.
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for (LiveRegMap::iterator i = LiveVirtRegs.begin(), e = LiveVirtRegs.end();
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i != e; ++i)
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spillVirtReg(MI, i);
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LiveVirtRegs.clear();
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isBulkSpilling = false;
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}
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/// usePhysReg - Handle the direct use of a physical register.
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/// Check that the register is not used by a virtreg.
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/// Kill the physreg, marking it free.
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/// This may add implicit kills to MO->getParent() and invalidate MO.
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void RAFast::usePhysReg(MachineOperand &MO) {
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unsigned PhysReg = MO.getReg();
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assert(TargetRegisterInfo::isPhysicalRegister(PhysReg) &&
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"Bad usePhysReg operand");
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// Ignore undef uses.
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if (MO.isUndef())
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return;
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markRegUsedInInstr(PhysReg);
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switch (PhysRegState[PhysReg]) {
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case regDisabled:
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break;
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case regReserved:
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PhysRegState[PhysReg] = regFree;
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// Fall through
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case regFree:
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MO.setIsKill();
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return;
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default:
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// The physreg was allocated to a virtual register. That means the value we
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// wanted has been clobbered.
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llvm_unreachable("Instruction uses an allocated register");
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}
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// Maybe a superregister is reserved?
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for (MCRegAliasIterator AI(PhysReg, TRI, false); AI.isValid(); ++AI) {
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unsigned Alias = *AI;
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switch (PhysRegState[Alias]) {
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case regDisabled:
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break;
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case regReserved:
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// Either PhysReg is a subregister of Alias and we mark the
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// whole register as free, or PhysReg is the superregister of
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// Alias and we mark all the aliases as disabled before freeing
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// PhysReg.
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// In the latter case, since PhysReg was disabled, this means that
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// its value is defined only by physical sub-registers. This check
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// is performed by the assert of the default case in this loop.
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// Note: The value of the superregister may only be partial
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// defined, that is why regDisabled is a valid state for aliases.
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assert((TRI->isSuperRegister(PhysReg, Alias) ||
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TRI->isSuperRegister(Alias, PhysReg)) &&
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"Instruction is not using a subregister of a reserved register");
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// Fall through.
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case regFree:
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if (TRI->isSuperRegister(PhysReg, Alias)) {
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// Leave the superregister in the working set.
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PhysRegState[Alias] = regFree;
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MO.getParent()->addRegisterKilled(Alias, TRI, true);
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return;
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}
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// Some other alias was in the working set - clear it.
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PhysRegState[Alias] = regDisabled;
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break;
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default:
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llvm_unreachable("Instruction uses an alias of an allocated register");
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}
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}
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// All aliases are disabled, bring register into working set.
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PhysRegState[PhysReg] = regFree;
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MO.setIsKill();
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}
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/// definePhysReg - Mark PhysReg as reserved or free after spilling any
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/// virtregs. This is very similar to defineVirtReg except the physreg is
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/// reserved instead of allocated.
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void RAFast::definePhysReg(MachineInstr &MI, unsigned PhysReg,
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RegState NewState) {
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markRegUsedInInstr(PhysReg);
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switch (unsigned VirtReg = PhysRegState[PhysReg]) {
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case regDisabled:
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break;
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default:
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spillVirtReg(MI, VirtReg);
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// Fall through.
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case regFree:
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case regReserved:
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PhysRegState[PhysReg] = NewState;
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return;
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}
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// This is a disabled register, disable all aliases.
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PhysRegState[PhysReg] = NewState;
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for (MCRegAliasIterator AI(PhysReg, TRI, false); AI.isValid(); ++AI) {
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unsigned Alias = *AI;
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switch (unsigned VirtReg = PhysRegState[Alias]) {
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case regDisabled:
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break;
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default:
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spillVirtReg(MI, VirtReg);
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// Fall through.
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case regFree:
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case regReserved:
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PhysRegState[Alias] = regDisabled;
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if (TRI->isSuperRegister(PhysReg, Alias))
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return;
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break;
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}
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}
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}
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// calcSpillCost - Return the cost of spilling clearing out PhysReg and
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// aliases so it is free for allocation.
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// Returns 0 when PhysReg is free or disabled with all aliases disabled - it
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// can be allocated directly.
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// Returns spillImpossible when PhysReg or an alias can't be spilled.
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unsigned RAFast::calcSpillCost(unsigned PhysReg) const {
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if (isRegUsedInInstr(PhysReg)) {
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DEBUG(dbgs() << PrintReg(PhysReg, TRI) << " is already used in instr.\n");
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return spillImpossible;
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}
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switch (unsigned VirtReg = PhysRegState[PhysReg]) {
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case regDisabled:
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break;
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case regFree:
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return 0;
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case regReserved:
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DEBUG(dbgs() << PrintReg(VirtReg, TRI) << " corresponding "
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<< PrintReg(PhysReg, TRI) << " is reserved already.\n");
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return spillImpossible;
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default: {
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LiveRegMap::const_iterator I = findLiveVirtReg(VirtReg);
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assert(I != LiveVirtRegs.end() && "Missing VirtReg entry");
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return I->Dirty ? spillDirty : spillClean;
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}
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}
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|
|
// This is a disabled register, add up cost of aliases.
|
|
DEBUG(dbgs() << PrintReg(PhysReg, TRI) << " is disabled.\n");
|
|
unsigned Cost = 0;
|
|
for (MCRegAliasIterator AI(PhysReg, TRI, false); AI.isValid(); ++AI) {
|
|
unsigned Alias = *AI;
|
|
switch (unsigned VirtReg = PhysRegState[Alias]) {
|
|
case regDisabled:
|
|
break;
|
|
case regFree:
|
|
++Cost;
|
|
break;
|
|
case regReserved:
|
|
return spillImpossible;
|
|
default: {
|
|
LiveRegMap::const_iterator I = findLiveVirtReg(VirtReg);
|
|
assert(I != LiveVirtRegs.end() && "Missing VirtReg entry");
|
|
Cost += I->Dirty ? spillDirty : spillClean;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
return Cost;
|
|
}
|
|
|
|
|
|
/// assignVirtToPhysReg - This method updates local state so that we know
|
|
/// that PhysReg is the proper container for VirtReg now. The physical
|
|
/// register must not be used for anything else when this is called.
|
|
///
|
|
void RAFast::assignVirtToPhysReg(LiveReg &LR, unsigned PhysReg) {
|
|
DEBUG(dbgs() << "Assigning " << PrintReg(LR.VirtReg, TRI) << " to "
|
|
<< PrintReg(PhysReg, TRI) << "\n");
|
|
PhysRegState[PhysReg] = LR.VirtReg;
|
|
assert(!LR.PhysReg && "Already assigned a physreg");
|
|
LR.PhysReg = PhysReg;
|
|
}
|
|
|
|
RAFast::LiveRegMap::iterator
|
|
RAFast::assignVirtToPhysReg(unsigned VirtReg, unsigned PhysReg) {
|
|
LiveRegMap::iterator LRI = findLiveVirtReg(VirtReg);
|
|
assert(LRI != LiveVirtRegs.end() && "VirtReg disappeared");
|
|
assignVirtToPhysReg(*LRI, PhysReg);
|
|
return LRI;
|
|
}
|
|
|
|
/// allocVirtReg - Allocate a physical register for VirtReg.
|
|
RAFast::LiveRegMap::iterator RAFast::allocVirtReg(MachineInstr &MI,
|
|
LiveRegMap::iterator LRI,
|
|
unsigned Hint) {
|
|
const unsigned VirtReg = LRI->VirtReg;
|
|
|
|
assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
|
|
"Can only allocate virtual registers");
|
|
|
|
const TargetRegisterClass *RC = MRI->getRegClass(VirtReg);
|
|
|
|
// Ignore invalid hints.
|
|
if (Hint && (!TargetRegisterInfo::isPhysicalRegister(Hint) ||
|
|
!RC->contains(Hint) || !MRI->isAllocatable(Hint)))
|
|
Hint = 0;
|
|
|
|
// Take hint when possible.
|
|
if (Hint) {
|
|
// Ignore the hint if we would have to spill a dirty register.
|
|
unsigned Cost = calcSpillCost(Hint);
|
|
if (Cost < spillDirty) {
|
|
if (Cost)
|
|
definePhysReg(MI, Hint, regFree);
|
|
// definePhysReg may kill virtual registers and modify LiveVirtRegs.
|
|
// That invalidates LRI, so run a new lookup for VirtReg.
|
|
return assignVirtToPhysReg(VirtReg, Hint);
|
|
}
|
|
}
|
|
|
|
ArrayRef<MCPhysReg> AO = RegClassInfo.getOrder(RC);
|
|
|
|
// First try to find a completely free register.
|
|
for (ArrayRef<MCPhysReg>::iterator I = AO.begin(), E = AO.end(); I != E; ++I){
|
|
unsigned PhysReg = *I;
|
|
if (PhysRegState[PhysReg] == regFree && !isRegUsedInInstr(PhysReg)) {
|
|
assignVirtToPhysReg(*LRI, PhysReg);
|
|
return LRI;
|
|
}
|
|
}
|
|
|
|
DEBUG(dbgs() << "Allocating " << PrintReg(VirtReg) << " from "
|
|
<< TRI->getRegClassName(RC) << "\n");
|
|
|
|
unsigned BestReg = 0, BestCost = spillImpossible;
|
|
for (ArrayRef<MCPhysReg>::iterator I = AO.begin(), E = AO.end(); I != E; ++I){
|
|
unsigned Cost = calcSpillCost(*I);
|
|
DEBUG(dbgs() << "\tRegister: " << PrintReg(*I, TRI) << "\n");
|
|
DEBUG(dbgs() << "\tCost: " << Cost << "\n");
|
|
DEBUG(dbgs() << "\tBestCost: " << BestCost << "\n");
|
|
// Cost is 0 when all aliases are already disabled.
|
|
if (Cost == 0) {
|
|
assignVirtToPhysReg(*LRI, *I);
|
|
return LRI;
|
|
}
|
|
if (Cost < BestCost)
|
|
BestReg = *I, BestCost = Cost;
|
|
}
|
|
|
|
if (BestReg) {
|
|
definePhysReg(MI, BestReg, regFree);
|
|
// definePhysReg may kill virtual registers and modify LiveVirtRegs.
|
|
// That invalidates LRI, so run a new lookup for VirtReg.
|
|
return assignVirtToPhysReg(VirtReg, BestReg);
|
|
}
|
|
|
|
// Nothing we can do. Report an error and keep going with a bad allocation.
|
|
if (MI.isInlineAsm())
|
|
MI.emitError("inline assembly requires more registers than available");
|
|
else
|
|
MI.emitError("ran out of registers during register allocation");
|
|
definePhysReg(MI, *AO.begin(), regFree);
|
|
return assignVirtToPhysReg(VirtReg, *AO.begin());
|
|
}
|
|
|
|
/// defineVirtReg - Allocate a register for VirtReg and mark it as dirty.
|
|
RAFast::LiveRegMap::iterator RAFast::defineVirtReg(MachineInstr &MI,
|
|
unsigned OpNum,
|
|
unsigned VirtReg,
|
|
unsigned Hint) {
|
|
assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
|
|
"Not a virtual register");
|
|
LiveRegMap::iterator LRI;
|
|
bool New;
|
|
std::tie(LRI, New) = LiveVirtRegs.insert(LiveReg(VirtReg));
|
|
if (New) {
|
|
// If there is no hint, peek at the only use of this register.
|
|
if ((!Hint || !TargetRegisterInfo::isPhysicalRegister(Hint)) &&
|
|
MRI->hasOneNonDBGUse(VirtReg)) {
|
|
const MachineInstr &UseMI = *MRI->use_instr_nodbg_begin(VirtReg);
|
|
// It's a copy, use the destination register as a hint.
|
|
if (UseMI.isCopyLike())
|
|
Hint = UseMI.getOperand(0).getReg();
|
|
}
|
|
LRI = allocVirtReg(MI, LRI, Hint);
|
|
} else if (LRI->LastUse) {
|
|
// Redefining a live register - kill at the last use, unless it is this
|
|
// instruction defining VirtReg multiple times.
|
|
if (LRI->LastUse != &MI || LRI->LastUse->getOperand(LRI->LastOpNum).isUse())
|
|
addKillFlag(*LRI);
|
|
}
|
|
assert(LRI->PhysReg && "Register not assigned");
|
|
LRI->LastUse = &MI;
|
|
LRI->LastOpNum = OpNum;
|
|
LRI->Dirty = true;
|
|
markRegUsedInInstr(LRI->PhysReg);
|
|
return LRI;
|
|
}
|
|
|
|
/// reloadVirtReg - Make sure VirtReg is available in a physreg and return it.
|
|
RAFast::LiveRegMap::iterator RAFast::reloadVirtReg(MachineInstr &MI,
|
|
unsigned OpNum,
|
|
unsigned VirtReg,
|
|
unsigned Hint) {
|
|
assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
|
|
"Not a virtual register");
|
|
LiveRegMap::iterator LRI;
|
|
bool New;
|
|
std::tie(LRI, New) = LiveVirtRegs.insert(LiveReg(VirtReg));
|
|
MachineOperand &MO = MI.getOperand(OpNum);
|
|
if (New) {
|
|
LRI = allocVirtReg(MI, LRI, Hint);
|
|
const TargetRegisterClass *RC = MRI->getRegClass(VirtReg);
|
|
int FrameIndex = getStackSpaceFor(VirtReg, RC);
|
|
DEBUG(dbgs() << "Reloading " << PrintReg(VirtReg, TRI) << " into "
|
|
<< PrintReg(LRI->PhysReg, TRI) << "\n");
|
|
TII->loadRegFromStackSlot(*MBB, MI, LRI->PhysReg, FrameIndex, RC, TRI);
|
|
++NumLoads;
|
|
} else if (LRI->Dirty) {
|
|
if (isLastUseOfLocalReg(MO)) {
|
|
DEBUG(dbgs() << "Killing last use: " << MO << "\n");
|
|
if (MO.isUse())
|
|
MO.setIsKill();
|
|
else
|
|
MO.setIsDead();
|
|
} else if (MO.isKill()) {
|
|
DEBUG(dbgs() << "Clearing dubious kill: " << MO << "\n");
|
|
MO.setIsKill(false);
|
|
} else if (MO.isDead()) {
|
|
DEBUG(dbgs() << "Clearing dubious dead: " << MO << "\n");
|
|
MO.setIsDead(false);
|
|
}
|
|
} else if (MO.isKill()) {
|
|
// We must remove kill flags from uses of reloaded registers because the
|
|
// register would be killed immediately, and there might be a second use:
|
|
// %foo = OR %x<kill>, %x
|
|
// This would cause a second reload of %x into a different register.
|
|
DEBUG(dbgs() << "Clearing clean kill: " << MO << "\n");
|
|
MO.setIsKill(false);
|
|
} else if (MO.isDead()) {
|
|
DEBUG(dbgs() << "Clearing clean dead: " << MO << "\n");
|
|
MO.setIsDead(false);
|
|
}
|
|
assert(LRI->PhysReg && "Register not assigned");
|
|
LRI->LastUse = &MI;
|
|
LRI->LastOpNum = OpNum;
|
|
markRegUsedInInstr(LRI->PhysReg);
|
|
return LRI;
|
|
}
|
|
|
|
// setPhysReg - Change operand OpNum in MI the refer the PhysReg, considering
|
|
// subregs. This may invalidate any operand pointers.
|
|
// Return true if the operand kills its register.
|
|
bool RAFast::setPhysReg(MachineInstr *MI, unsigned OpNum, unsigned PhysReg) {
|
|
MachineOperand &MO = MI->getOperand(OpNum);
|
|
bool Dead = MO.isDead();
|
|
if (!MO.getSubReg()) {
|
|
MO.setReg(PhysReg);
|
|
return MO.isKill() || Dead;
|
|
}
|
|
|
|
// Handle subregister index.
|
|
MO.setReg(PhysReg ? TRI->getSubReg(PhysReg, MO.getSubReg()) : 0);
|
|
MO.setSubReg(0);
|
|
|
|
// A kill flag implies killing the full register. Add corresponding super
|
|
// register kill.
|
|
if (MO.isKill()) {
|
|
MI->addRegisterKilled(PhysReg, TRI, true);
|
|
return true;
|
|
}
|
|
|
|
// A <def,read-undef> of a sub-register requires an implicit def of the full
|
|
// register.
|
|
if (MO.isDef() && MO.isUndef())
|
|
MI->addRegisterDefined(PhysReg, TRI);
|
|
|
|
return Dead;
|
|
}
|
|
|
|
// Handle special instruction operand like early clobbers and tied ops when
|
|
// there are additional physreg defines.
|
|
void RAFast::handleThroughOperands(MachineInstr *MI,
|
|
SmallVectorImpl<unsigned> &VirtDead) {
|
|
DEBUG(dbgs() << "Scanning for through registers:");
|
|
SmallSet<unsigned, 8> ThroughRegs;
|
|
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 (MO.isEarlyClobber() || MI->isRegTiedToDefOperand(i) ||
|
|
(MO.getSubReg() && MI->readsVirtualRegister(Reg))) {
|
|
if (ThroughRegs.insert(Reg).second)
|
|
DEBUG(dbgs() << ' ' << PrintReg(Reg));
|
|
}
|
|
}
|
|
|
|
// If any physreg defines collide with preallocated through registers,
|
|
// we must spill and reallocate.
|
|
DEBUG(dbgs() << "\nChecking for physdef collisions.\n");
|
|
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
if (!MO.isReg() || !MO.isDef()) continue;
|
|
unsigned Reg = MO.getReg();
|
|
if (!Reg || !TargetRegisterInfo::isPhysicalRegister(Reg)) continue;
|
|
markRegUsedInInstr(Reg);
|
|
for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) {
|
|
if (ThroughRegs.count(PhysRegState[*AI]))
|
|
definePhysReg(*MI, *AI, regFree);
|
|
}
|
|
}
|
|
|
|
SmallVector<unsigned, 8> PartialDefs;
|
|
DEBUG(dbgs() << "Allocating tied uses.\n");
|
|
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 (MO.isUse()) {
|
|
unsigned DefIdx = 0;
|
|
if (!MI->isRegTiedToDefOperand(i, &DefIdx)) continue;
|
|
DEBUG(dbgs() << "Operand " << i << "("<< MO << ") is tied to operand "
|
|
<< DefIdx << ".\n");
|
|
LiveRegMap::iterator LRI = reloadVirtReg(*MI, i, Reg, 0);
|
|
unsigned PhysReg = LRI->PhysReg;
|
|
setPhysReg(MI, i, PhysReg);
|
|
// Note: we don't update the def operand yet. That would cause the normal
|
|
// def-scan to attempt spilling.
|
|
} else if (MO.getSubReg() && MI->readsVirtualRegister(Reg)) {
|
|
DEBUG(dbgs() << "Partial redefine: " << MO << "\n");
|
|
// Reload the register, but don't assign to the operand just yet.
|
|
// That would confuse the later phys-def processing pass.
|
|
LiveRegMap::iterator LRI = reloadVirtReg(*MI, i, Reg, 0);
|
|
PartialDefs.push_back(LRI->PhysReg);
|
|
}
|
|
}
|
|
|
|
DEBUG(dbgs() << "Allocating early clobbers.\n");
|
|
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 (!MO.isEarlyClobber())
|
|
continue;
|
|
// Note: defineVirtReg may invalidate MO.
|
|
LiveRegMap::iterator LRI = defineVirtReg(*MI, i, Reg, 0);
|
|
unsigned PhysReg = LRI->PhysReg;
|
|
if (setPhysReg(MI, i, PhysReg))
|
|
VirtDead.push_back(Reg);
|
|
}
|
|
|
|
// Restore UsedInInstr to a state usable for allocating normal virtual uses.
|
|
UsedInInstr.clear();
|
|
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
if (!MO.isReg() || (MO.isDef() && !MO.isEarlyClobber())) continue;
|
|
unsigned Reg = MO.getReg();
|
|
if (!Reg || !TargetRegisterInfo::isPhysicalRegister(Reg)) continue;
|
|
DEBUG(dbgs() << "\tSetting " << PrintReg(Reg, TRI)
|
|
<< " as used in instr\n");
|
|
markRegUsedInInstr(Reg);
|
|
}
|
|
|
|
// Also mark PartialDefs as used to avoid reallocation.
|
|
for (unsigned i = 0, e = PartialDefs.size(); i != e; ++i)
|
|
markRegUsedInInstr(PartialDefs[i]);
|
|
}
|
|
|
|
void RAFast::AllocateBasicBlock() {
|
|
DEBUG(dbgs() << "\nAllocating " << *MBB);
|
|
|
|
PhysRegState.assign(TRI->getNumRegs(), regDisabled);
|
|
assert(LiveVirtRegs.empty() && "Mapping not cleared from last block?");
|
|
|
|
MachineBasicBlock::iterator MII = MBB->begin();
|
|
|
|
// Add live-in registers as live.
|
|
for (const auto &LI : MBB->liveins())
|
|
if (MRI->isAllocatable(LI.PhysReg))
|
|
definePhysReg(*MII, LI.PhysReg, regReserved);
|
|
|
|
SmallVector<unsigned, 8> VirtDead;
|
|
SmallVector<MachineInstr*, 32> Coalesced;
|
|
|
|
// Otherwise, sequentially allocate each instruction in the MBB.
|
|
while (MII != MBB->end()) {
|
|
MachineInstr *MI = &*MII++;
|
|
const MCInstrDesc &MCID = MI->getDesc();
|
|
DEBUG({
|
|
dbgs() << "\n>> " << *MI << "Regs:";
|
|
for (unsigned Reg = 1, E = TRI->getNumRegs(); Reg != E; ++Reg) {
|
|
if (PhysRegState[Reg] == regDisabled) continue;
|
|
dbgs() << " " << TRI->getName(Reg);
|
|
switch(PhysRegState[Reg]) {
|
|
case regFree:
|
|
break;
|
|
case regReserved:
|
|
dbgs() << "*";
|
|
break;
|
|
default: {
|
|
dbgs() << '=' << PrintReg(PhysRegState[Reg]);
|
|
LiveRegMap::iterator I = findLiveVirtReg(PhysRegState[Reg]);
|
|
assert(I != LiveVirtRegs.end() && "Missing VirtReg entry");
|
|
if (I->Dirty)
|
|
dbgs() << "*";
|
|
assert(I->PhysReg == Reg && "Bad inverse map");
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
dbgs() << '\n';
|
|
// Check that LiveVirtRegs is the inverse.
|
|
for (LiveRegMap::iterator i = LiveVirtRegs.begin(),
|
|
e = LiveVirtRegs.end(); i != e; ++i) {
|
|
assert(TargetRegisterInfo::isVirtualRegister(i->VirtReg) &&
|
|
"Bad map key");
|
|
assert(TargetRegisterInfo::isPhysicalRegister(i->PhysReg) &&
|
|
"Bad map value");
|
|
assert(PhysRegState[i->PhysReg] == i->VirtReg && "Bad inverse map");
|
|
}
|
|
});
|
|
|
|
// Debug values are not allowed to change codegen in any way.
|
|
if (MI->isDebugValue()) {
|
|
bool ScanDbgValue = true;
|
|
while (ScanDbgValue) {
|
|
ScanDbgValue = false;
|
|
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;
|
|
LiveRegMap::iterator LRI = findLiveVirtReg(Reg);
|
|
if (LRI != LiveVirtRegs.end())
|
|
setPhysReg(MI, i, LRI->PhysReg);
|
|
else {
|
|
int SS = StackSlotForVirtReg[Reg];
|
|
if (SS == -1) {
|
|
// We can't allocate a physreg for a DebugValue, sorry!
|
|
DEBUG(dbgs() << "Unable to allocate vreg used by DBG_VALUE");
|
|
MO.setReg(0);
|
|
}
|
|
else {
|
|
// Modify DBG_VALUE now that the value is in a spill slot.
|
|
bool IsIndirect = MI->isIndirectDebugValue();
|
|
uint64_t Offset = IsIndirect ? MI->getOperand(1).getImm() : 0;
|
|
const MDNode *Var = MI->getDebugVariable();
|
|
const MDNode *Expr = MI->getDebugExpression();
|
|
DebugLoc DL = MI->getDebugLoc();
|
|
MachineBasicBlock *MBB = MI->getParent();
|
|
assert(
|
|
cast<DILocalVariable>(Var)->isValidLocationForIntrinsic(DL) &&
|
|
"Expected inlined-at fields to agree");
|
|
MachineInstr *NewDV = BuildMI(*MBB, MBB->erase(MI), DL,
|
|
TII->get(TargetOpcode::DBG_VALUE))
|
|
.addFrameIndex(SS)
|
|
.addImm(Offset)
|
|
.addMetadata(Var)
|
|
.addMetadata(Expr);
|
|
DEBUG(dbgs() << "Modifying debug info due to spill:"
|
|
<< "\t" << *NewDV);
|
|
// Scan NewDV operands from the beginning.
|
|
MI = NewDV;
|
|
ScanDbgValue = true;
|
|
break;
|
|
}
|
|
}
|
|
LiveDbgValueMap[Reg].push_back(MI);
|
|
}
|
|
}
|
|
// Next instruction.
|
|
continue;
|
|
}
|
|
|
|
// If this is a copy, we may be able to coalesce.
|
|
unsigned CopySrc = 0, CopyDst = 0, CopySrcSub = 0, CopyDstSub = 0;
|
|
if (MI->isCopy()) {
|
|
CopyDst = MI->getOperand(0).getReg();
|
|
CopySrc = MI->getOperand(1).getReg();
|
|
CopyDstSub = MI->getOperand(0).getSubReg();
|
|
CopySrcSub = MI->getOperand(1).getSubReg();
|
|
}
|
|
|
|
// Track registers used by instruction.
|
|
UsedInInstr.clear();
|
|
|
|
// First scan.
|
|
// Mark physreg uses and early clobbers as used.
|
|
// Find the end of the virtreg operands
|
|
unsigned VirtOpEnd = 0;
|
|
bool hasTiedOps = false;
|
|
bool hasEarlyClobbers = false;
|
|
bool hasPartialRedefs = false;
|
|
bool hasPhysDefs = false;
|
|
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
// Make sure MRI knows about registers clobbered by regmasks.
|
|
if (MO.isRegMask()) {
|
|
MRI->addPhysRegsUsedFromRegMask(MO.getRegMask());
|
|
continue;
|
|
}
|
|
if (!MO.isReg()) continue;
|
|
unsigned Reg = MO.getReg();
|
|
if (!Reg) continue;
|
|
if (TargetRegisterInfo::isVirtualRegister(Reg)) {
|
|
VirtOpEnd = i+1;
|
|
if (MO.isUse()) {
|
|
hasTiedOps = hasTiedOps ||
|
|
MCID.getOperandConstraint(i, MCOI::TIED_TO) != -1;
|
|
} else {
|
|
if (MO.isEarlyClobber())
|
|
hasEarlyClobbers = true;
|
|
if (MO.getSubReg() && MI->readsVirtualRegister(Reg))
|
|
hasPartialRedefs = true;
|
|
}
|
|
continue;
|
|
}
|
|
if (!MRI->isAllocatable(Reg)) continue;
|
|
if (MO.isUse()) {
|
|
usePhysReg(MO);
|
|
} else if (MO.isEarlyClobber()) {
|
|
definePhysReg(*MI, Reg,
|
|
(MO.isImplicit() || MO.isDead()) ? regFree : regReserved);
|
|
hasEarlyClobbers = true;
|
|
} else
|
|
hasPhysDefs = true;
|
|
}
|
|
|
|
// The instruction may have virtual register operands that must be allocated
|
|
// the same register at use-time and def-time: early clobbers and tied
|
|
// operands. If there are also physical defs, these registers must avoid
|
|
// both physical defs and uses, making them more constrained than normal
|
|
// operands.
|
|
// Similarly, if there are multiple defs and tied operands, we must make
|
|
// sure the same register is allocated to uses and defs.
|
|
// We didn't detect inline asm tied operands above, so just make this extra
|
|
// pass for all inline asm.
|
|
if (MI->isInlineAsm() || hasEarlyClobbers || hasPartialRedefs ||
|
|
(hasTiedOps && (hasPhysDefs || MCID.getNumDefs() > 1))) {
|
|
handleThroughOperands(MI, VirtDead);
|
|
// Don't attempt coalescing when we have funny stuff going on.
|
|
CopyDst = 0;
|
|
// Pretend we have early clobbers so the use operands get marked below.
|
|
// This is not necessary for the common case of a single tied use.
|
|
hasEarlyClobbers = true;
|
|
}
|
|
|
|
// Second scan.
|
|
// Allocate virtreg uses.
|
|
for (unsigned i = 0; i != VirtOpEnd; ++i) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
if (!MO.isReg()) continue;
|
|
unsigned Reg = MO.getReg();
|
|
if (!TargetRegisterInfo::isVirtualRegister(Reg)) continue;
|
|
if (MO.isUse()) {
|
|
LiveRegMap::iterator LRI = reloadVirtReg(*MI, i, Reg, CopyDst);
|
|
unsigned PhysReg = LRI->PhysReg;
|
|
CopySrc = (CopySrc == Reg || CopySrc == PhysReg) ? PhysReg : 0;
|
|
if (setPhysReg(MI, i, PhysReg))
|
|
killVirtReg(LRI);
|
|
}
|
|
}
|
|
|
|
// Track registers defined by instruction - early clobbers and tied uses at
|
|
// this point.
|
|
UsedInInstr.clear();
|
|
if (hasEarlyClobbers) {
|
|
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
if (!MO.isReg()) continue;
|
|
unsigned Reg = MO.getReg();
|
|
if (!Reg || !TargetRegisterInfo::isPhysicalRegister(Reg)) continue;
|
|
// Look for physreg defs and tied uses.
|
|
if (!MO.isDef() && !MI->isRegTiedToDefOperand(i)) continue;
|
|
markRegUsedInInstr(Reg);
|
|
}
|
|
}
|
|
|
|
unsigned DefOpEnd = MI->getNumOperands();
|
|
if (MI->isCall()) {
|
|
// Spill all virtregs before a call. This serves one purpose: If an
|
|
// exception is thrown, the landing pad is going to expect to find
|
|
// registers in their spill slots.
|
|
// Note: although this is appealing to just consider all definitions
|
|
// as call-clobbered, this is not correct because some of those
|
|
// definitions may be used later on and we do not want to reuse
|
|
// those for virtual registers in between.
|
|
DEBUG(dbgs() << " Spilling remaining registers before call.\n");
|
|
spillAll(MI);
|
|
|
|
// The imp-defs are skipped below, but we still need to mark those
|
|
// registers as used by the function.
|
|
SkippedInstrs.insert(&MCID);
|
|
}
|
|
|
|
// Third scan.
|
|
// Allocate defs and collect dead defs.
|
|
for (unsigned i = 0; i != DefOpEnd; ++i) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
if (!MO.isReg() || !MO.isDef() || !MO.getReg() || MO.isEarlyClobber())
|
|
continue;
|
|
unsigned Reg = MO.getReg();
|
|
|
|
if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
|
|
if (!MRI->isAllocatable(Reg)) continue;
|
|
definePhysReg(*MI, Reg, MO.isDead() ? regFree : regReserved);
|
|
continue;
|
|
}
|
|
LiveRegMap::iterator LRI = defineVirtReg(*MI, i, Reg, CopySrc);
|
|
unsigned PhysReg = LRI->PhysReg;
|
|
if (setPhysReg(MI, i, PhysReg)) {
|
|
VirtDead.push_back(Reg);
|
|
CopyDst = 0; // cancel coalescing;
|
|
} else
|
|
CopyDst = (CopyDst == Reg || CopyDst == PhysReg) ? PhysReg : 0;
|
|
}
|
|
|
|
// Kill dead defs after the scan to ensure that multiple defs of the same
|
|
// register are allocated identically. We didn't need to do this for uses
|
|
// because we are crerating our own kill flags, and they are always at the
|
|
// last use.
|
|
for (unsigned i = 0, e = VirtDead.size(); i != e; ++i)
|
|
killVirtReg(VirtDead[i]);
|
|
VirtDead.clear();
|
|
|
|
if (CopyDst && CopyDst == CopySrc && CopyDstSub == CopySrcSub) {
|
|
DEBUG(dbgs() << "-- coalescing: " << *MI);
|
|
Coalesced.push_back(MI);
|
|
} else {
|
|
DEBUG(dbgs() << "<< " << *MI);
|
|
}
|
|
}
|
|
|
|
// Spill all physical registers holding virtual registers now.
|
|
DEBUG(dbgs() << "Spilling live registers at end of block.\n");
|
|
spillAll(MBB->getFirstTerminator());
|
|
|
|
// Erase all the coalesced copies. We are delaying it until now because
|
|
// LiveVirtRegs might refer to the instrs.
|
|
for (unsigned i = 0, e = Coalesced.size(); i != e; ++i)
|
|
MBB->erase(Coalesced[i]);
|
|
NumCopies += Coalesced.size();
|
|
|
|
DEBUG(MBB->dump());
|
|
}
|
|
|
|
/// runOnMachineFunction - Register allocate the whole function
|
|
///
|
|
bool RAFast::runOnMachineFunction(MachineFunction &Fn) {
|
|
DEBUG(dbgs() << "********** FAST REGISTER ALLOCATION **********\n"
|
|
<< "********** Function: " << Fn.getName() << '\n');
|
|
MF = &Fn;
|
|
MRI = &MF->getRegInfo();
|
|
TRI = MF->getSubtarget().getRegisterInfo();
|
|
TII = MF->getSubtarget().getInstrInfo();
|
|
MRI->freezeReservedRegs(Fn);
|
|
RegClassInfo.runOnMachineFunction(Fn);
|
|
UsedInInstr.clear();
|
|
UsedInInstr.setUniverse(TRI->getNumRegUnits());
|
|
|
|
assert(!MRI->isSSA() && "regalloc requires leaving SSA");
|
|
|
|
// initialize the virtual->physical register map to have a 'null'
|
|
// mapping for all virtual registers
|
|
StackSlotForVirtReg.resize(MRI->getNumVirtRegs());
|
|
LiveVirtRegs.setUniverse(MRI->getNumVirtRegs());
|
|
|
|
// Loop over all of the basic blocks, eliminating virtual register references
|
|
for (MachineFunction::iterator MBBi = Fn.begin(), MBBe = Fn.end();
|
|
MBBi != MBBe; ++MBBi) {
|
|
MBB = &*MBBi;
|
|
AllocateBasicBlock();
|
|
}
|
|
|
|
// All machine operands and other references to virtual registers have been
|
|
// replaced. Remove the virtual registers.
|
|
MRI->clearVirtRegs();
|
|
|
|
SkippedInstrs.clear();
|
|
StackSlotForVirtReg.clear();
|
|
LiveDbgValueMap.clear();
|
|
return true;
|
|
}
|
|
|
|
FunctionPass *llvm::createFastRegisterAllocator() {
|
|
return new RAFast();
|
|
}
|