1 //===-- PhyRegAlloc.cpp ---------------------------------------------------===//
3 // Register allocation for LLVM.
5 //===----------------------------------------------------------------------===//
7 #include "llvm/CodeGen/RegisterAllocation.h"
8 #include "llvm/CodeGen/RegAllocCommon.h"
9 #include "llvm/CodeGen/PhyRegAlloc.h"
10 #include "llvm/CodeGen/MachineInstr.h"
11 #include "llvm/CodeGen/MachineInstrAnnot.h"
12 #include "llvm/CodeGen/MachineFunction.h"
13 #include "llvm/Analysis/LiveVar/FunctionLiveVarInfo.h"
14 #include "llvm/Analysis/LoopInfo.h"
15 #include "llvm/Target/TargetMachine.h"
16 #include "llvm/Target/MachineFrameInfo.h"
17 #include "llvm/Target/MachineInstrInfo.h"
18 #include "llvm/Function.h"
19 #include "llvm/Type.h"
20 #include "llvm/iOther.h"
21 #include "Support/STLExtras.h"
22 #include "Support/CommandLine.h"
27 RegAllocDebugLevel_t DEBUG_RA;
29 static cl::opt<RegAllocDebugLevel_t, true>
30 DRA_opt("dregalloc", cl::Hidden, cl::location(DEBUG_RA),
31 cl::desc("enable register allocation debugging information"),
33 clEnumValN(RA_DEBUG_None , "n", "disable debug output"),
34 clEnumValN(RA_DEBUG_Results, "y", "debug output for allocation results"),
35 clEnumValN(RA_DEBUG_Coloring, "c", "debug output for graph coloring step"),
36 clEnumValN(RA_DEBUG_Interference,"ig","debug output for interference graphs"),
37 clEnumValN(RA_DEBUG_LiveRanges , "lr","debug output for live ranges"),
38 clEnumValN(RA_DEBUG_Verbose, "v", "extra debug output"),
41 //----------------------------------------------------------------------------
42 // RegisterAllocation pass front end...
43 //----------------------------------------------------------------------------
45 class RegisterAllocator : public FunctionPass {
46 TargetMachine &Target;
48 inline RegisterAllocator(TargetMachine &T) : Target(T) {}
50 const char *getPassName() const { return "Register Allocation"; }
52 bool runOnFunction(Function &F) {
54 cerr << "\n********* Function "<< F.getName() << " ***********\n";
56 PhyRegAlloc PRA(&F, Target, &getAnalysis<FunctionLiveVarInfo>(),
57 &getAnalysis<LoopInfo>());
58 PRA.allocateRegisters();
60 if (DEBUG_RA) cerr << "\nRegister allocation complete!\n";
64 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
65 AU.addRequired<LoopInfo>();
66 AU.addRequired<FunctionLiveVarInfo>();
71 Pass *getRegisterAllocator(TargetMachine &T) {
72 return new RegisterAllocator(T);
75 //----------------------------------------------------------------------------
76 // Constructor: Init local composite objects and create register classes.
77 //----------------------------------------------------------------------------
78 PhyRegAlloc::PhyRegAlloc(Function *F, const TargetMachine& tm,
79 FunctionLiveVarInfo *Lvi, LoopInfo *LDC)
80 : TM(tm), Fn(F), MF(MachineFunction::get(F)), LVI(Lvi),
81 LRI(F, tm, RegClassList), MRI(tm.getRegInfo()),
82 NumOfRegClasses(MRI.getNumOfRegClasses()), LoopDepthCalc(LDC) {
84 // create each RegisterClass and put in RegClassList
86 for (unsigned rc=0; rc != NumOfRegClasses; rc++)
87 RegClassList.push_back(new RegClass(F, MRI.getMachineRegClass(rc),
92 //----------------------------------------------------------------------------
93 // Destructor: Deletes register classes
94 //----------------------------------------------------------------------------
95 PhyRegAlloc::~PhyRegAlloc() {
96 for ( unsigned rc=0; rc < NumOfRegClasses; rc++)
97 delete RegClassList[rc];
99 AddedInstrMap.clear();
102 //----------------------------------------------------------------------------
103 // This method initally creates interference graphs (one in each reg class)
104 // and IGNodeList (one in each IG). The actual nodes will be pushed later.
105 //----------------------------------------------------------------------------
106 void PhyRegAlloc::createIGNodeListsAndIGs() {
107 if (DEBUG_RA >= RA_DEBUG_LiveRanges) cerr << "Creating LR lists ...\n";
110 LiveRangeMapType::const_iterator HMI = LRI.getLiveRangeMap()->begin();
113 LiveRangeMapType::const_iterator HMIEnd = LRI.getLiveRangeMap()->end();
115 for (; HMI != HMIEnd ; ++HMI ) {
117 LiveRange *L = HMI->second; // get the LiveRange
120 cerr << "\n**** ?!?WARNING: NULL LIVE RANGE FOUND FOR: "
121 << RAV(HMI->first) << "****\n";
125 // if the Value * is not null, and LR is not yet written to the IGNodeList
126 if (!(L->getUserIGNode()) ) {
127 RegClass *const RC = // RegClass of first value in the LR
128 RegClassList[ L->getRegClass()->getID() ];
129 RC->addLRToIG(L); // add this LR to an IG
135 for ( unsigned rc=0; rc < NumOfRegClasses ; rc++)
136 RegClassList[rc]->createInterferenceGraph();
138 if (DEBUG_RA >= RA_DEBUG_LiveRanges) cerr << "LRLists Created!\n";
142 //----------------------------------------------------------------------------
143 // This method will add all interferences at for a given instruction.
144 // Interence occurs only if the LR of Def (Inst or Arg) is of the same reg
145 // class as that of live var. The live var passed to this function is the
146 // LVset AFTER the instruction
147 //----------------------------------------------------------------------------
149 void PhyRegAlloc::addInterference(const Value *Def,
150 const ValueSet *LVSet,
153 ValueSet::const_iterator LIt = LVSet->begin();
155 // get the live range of instruction
157 const LiveRange *const LROfDef = LRI.getLiveRangeForValue( Def );
159 IGNode *const IGNodeOfDef = LROfDef->getUserIGNode();
160 assert( IGNodeOfDef );
162 RegClass *const RCOfDef = LROfDef->getRegClass();
164 // for each live var in live variable set
166 for ( ; LIt != LVSet->end(); ++LIt) {
168 if (DEBUG_RA >= RA_DEBUG_Verbose)
169 cerr << "< Def=" << RAV(Def) << ", Lvar=" << RAV(*LIt) << "> ";
171 // get the live range corresponding to live var
173 LiveRange *LROfVar = LRI.getLiveRangeForValue(*LIt);
175 // LROfVar can be null if it is a const since a const
176 // doesn't have a dominating def - see Assumptions above
179 if (LROfDef != LROfVar) // do not set interf for same LR
180 if (RCOfDef == LROfVar->getRegClass()) // 2 reg classes are the same
181 RCOfDef->setInterference( LROfDef, LROfVar);
187 //----------------------------------------------------------------------------
188 // For a call instruction, this method sets the CallInterference flag in
189 // the LR of each variable live int the Live Variable Set live after the
190 // call instruction (except the return value of the call instruction - since
191 // the return value does not interfere with that call itself).
192 //----------------------------------------------------------------------------
194 void PhyRegAlloc::setCallInterferences(const MachineInstr *MInst,
195 const ValueSet *LVSetAft) {
197 if (DEBUG_RA >= RA_DEBUG_Interference)
198 cerr << "\n For call inst: " << *MInst;
200 ValueSet::const_iterator LIt = LVSetAft->begin();
202 // for each live var in live variable set after machine inst
204 for ( ; LIt != LVSetAft->end(); ++LIt) {
206 // get the live range corresponding to live var
208 LiveRange *const LR = LRI.getLiveRangeForValue(*LIt );
210 // LR can be null if it is a const since a const
211 // doesn't have a dominating def - see Assumptions above
214 if (DEBUG_RA >= RA_DEBUG_Interference) {
215 cerr << "\n\tLR after Call: ";
218 LR->setCallInterference();
219 if (DEBUG_RA >= RA_DEBUG_Interference) {
220 cerr << "\n ++After adding call interference for LR: " ;
227 // Now find the LR of the return value of the call
228 // We do this because, we look at the LV set *after* the instruction
229 // to determine, which LRs must be saved across calls. The return value
230 // of the call is live in this set - but it does not interfere with call
231 // (i.e., we can allocate a volatile register to the return value)
233 CallArgsDescriptor* argDesc = CallArgsDescriptor::get(MInst);
235 if (const Value *RetVal = argDesc->getReturnValue()) {
236 LiveRange *RetValLR = LRI.getLiveRangeForValue( RetVal );
237 assert( RetValLR && "No LR for RetValue of call");
238 RetValLR->clearCallInterference();
241 // If the CALL is an indirect call, find the LR of the function pointer.
242 // That has a call interference because it conflicts with outgoing args.
243 if (const Value *AddrVal = argDesc->getIndirectFuncPtr()) {
244 LiveRange *AddrValLR = LRI.getLiveRangeForValue( AddrVal );
245 assert( AddrValLR && "No LR for indirect addr val of call");
246 AddrValLR->setCallInterference();
254 //----------------------------------------------------------------------------
255 // This method will walk thru code and create interferences in the IG of
256 // each RegClass. Also, this method calculates the spill cost of each
257 // Live Range (it is done in this method to save another pass over the code).
258 //----------------------------------------------------------------------------
259 void PhyRegAlloc::buildInterferenceGraphs()
262 if (DEBUG_RA >= RA_DEBUG_Interference)
263 cerr << "Creating interference graphs ...\n";
265 unsigned BBLoopDepthCost;
266 for (MachineFunction::iterator BBI = MF.begin(), BBE = MF.end();
268 const MachineBasicBlock &MBB = *BBI;
269 const BasicBlock *BB = MBB.getBasicBlock();
271 // find the 10^(loop_depth) of this BB
273 BBLoopDepthCost = (unsigned)pow(10.0, LoopDepthCalc->getLoopDepth(BB));
275 // get the iterator for machine instructions
277 MachineBasicBlock::const_iterator MII = MBB.begin();
279 // iterate over all the machine instructions in BB
281 for ( ; MII != MBB.end(); ++MII) {
282 const MachineInstr *MInst = *MII;
284 // get the LV set after the instruction
286 const ValueSet &LVSetAI = LVI->getLiveVarSetAfterMInst(MInst, BB);
287 bool isCallInst = TM.getInstrInfo().isCall(MInst->getOpCode());
290 // set the isCallInterference flag of each live range wich extends
291 // accross this call instruction. This information is used by graph
292 // coloring algo to avoid allocating volatile colors to live ranges
293 // that span across calls (since they have to be saved/restored)
295 setCallInterferences(MInst, &LVSetAI);
298 // iterate over all MI operands to find defs
300 for (MachineInstr::const_val_op_iterator OpI = MInst->begin(),
301 OpE = MInst->end(); OpI != OpE; ++OpI) {
302 if (OpI.isDef()) // create a new LR iff this operand is a def
303 addInterference(*OpI, &LVSetAI, isCallInst);
305 // Calculate the spill cost of each live range
307 LiveRange *LR = LRI.getLiveRangeForValue(*OpI);
308 if (LR) LR->addSpillCost(BBLoopDepthCost);
312 // if there are multiple defs in this instruction e.g. in SETX
314 if (TM.getInstrInfo().isPseudoInstr(MInst->getOpCode()))
315 addInterf4PseudoInstr(MInst);
318 // Also add interference for any implicit definitions in a machine
319 // instr (currently, only calls have this).
321 unsigned NumOfImpRefs = MInst->getNumImplicitRefs();
322 if ( NumOfImpRefs > 0 ) {
323 for (unsigned z=0; z < NumOfImpRefs; z++)
324 if (MInst->implicitRefIsDefined(z) )
325 addInterference( MInst->getImplicitRef(z), &LVSetAI, isCallInst );
329 } // for all machine instructions in BB
330 } // for all BBs in function
333 // add interferences for function arguments. Since there are no explict
334 // defs in the function for args, we have to add them manually
336 addInterferencesForArgs();
338 if (DEBUG_RA >= RA_DEBUG_Interference)
339 cerr << "Interference graphs calculated!\n";
344 //--------------------------------------------------------------------------
345 // Pseudo instructions will be exapnded to multiple instructions by the
346 // assembler. Consequently, all the opernds must get distinct registers.
347 // Therefore, we mark all operands of a pseudo instruction as they interfere
349 //--------------------------------------------------------------------------
350 void PhyRegAlloc::addInterf4PseudoInstr(const MachineInstr *MInst) {
352 bool setInterf = false;
354 // iterate over MI operands to find defs
356 for (MachineInstr::const_val_op_iterator It1 = MInst->begin(),
357 ItE = MInst->end(); It1 != ItE; ++It1) {
358 const LiveRange *LROfOp1 = LRI.getLiveRangeForValue(*It1);
359 assert((LROfOp1 || !It1.isDef()) && "No LR for Def in PSEUDO insruction");
361 MachineInstr::const_val_op_iterator It2 = It1;
362 for (++It2; It2 != ItE; ++It2) {
363 const LiveRange *LROfOp2 = LRI.getLiveRangeForValue(*It2);
366 RegClass *RCOfOp1 = LROfOp1->getRegClass();
367 RegClass *RCOfOp2 = LROfOp2->getRegClass();
369 if (RCOfOp1 == RCOfOp2 ){
370 RCOfOp1->setInterference( LROfOp1, LROfOp2 );
374 } // for all other defs in machine instr
375 } // for all operands in an instruction
377 if (!setInterf && MInst->getNumOperands() > 2) {
378 cerr << "\nInterf not set for any operand in pseudo instr:\n";
380 assert(0 && "Interf not set for pseudo instr with > 2 operands" );
386 //----------------------------------------------------------------------------
387 // This method will add interferences for incoming arguments to a function.
388 //----------------------------------------------------------------------------
390 void PhyRegAlloc::addInterferencesForArgs() {
391 // get the InSet of root BB
392 const ValueSet &InSet = LVI->getInSetOfBB(&Fn->front());
394 for (Function::const_aiterator AI = Fn->abegin(); AI != Fn->aend(); ++AI) {
395 // add interferences between args and LVars at start
396 addInterference(AI, &InSet, false);
398 if (DEBUG_RA >= RA_DEBUG_Interference)
399 cerr << " - %% adding interference for argument " << RAV(AI) << "\n";
404 //----------------------------------------------------------------------------
405 // This method is called after register allocation is complete to set the
406 // allocated reisters in the machine code. This code will add register numbers
407 // to MachineOperands that contain a Value. Also it calls target specific
408 // methods to produce caller saving instructions. At the end, it adds all
409 // additional instructions produced by the register allocator to the
410 // instruction stream.
411 //----------------------------------------------------------------------------
413 //-----------------------------
414 // Utility functions used below
415 //-----------------------------
417 InsertBefore(MachineInstr* newMI,
418 MachineBasicBlock& MBB,
419 MachineBasicBlock::iterator& MII)
421 MII = MBB.insert(MII, newMI);
426 InsertAfter(MachineInstr* newMI,
427 MachineBasicBlock& MBB,
428 MachineBasicBlock::iterator& MII)
430 ++MII; // insert before the next instruction
431 MII = MBB.insert(MII, newMI);
435 SubstituteInPlace(MachineInstr* newMI,
436 MachineBasicBlock& MBB,
437 MachineBasicBlock::iterator MII)
443 PrependInstructions(vector<MachineInstr *> &IBef,
444 MachineBasicBlock& MBB,
445 MachineBasicBlock::iterator& MII,
446 const std::string& msg)
450 MachineInstr* OrigMI = *MII;
451 std::vector<MachineInstr *>::iterator AdIt;
452 for (AdIt = IBef.begin(); AdIt != IBef.end() ; ++AdIt)
455 if (OrigMI) cerr << "For MInst:\n " << *OrigMI;
456 cerr << msg << "PREPENDed instr:\n " << **AdIt << "\n";
458 InsertBefore(*AdIt, MBB, MII);
464 AppendInstructions(std::vector<MachineInstr *> &IAft,
465 MachineBasicBlock& MBB,
466 MachineBasicBlock::iterator& MII,
467 const std::string& msg)
471 MachineInstr* OrigMI = *MII;
472 std::vector<MachineInstr *>::iterator AdIt;
473 for ( AdIt = IAft.begin(); AdIt != IAft.end() ; ++AdIt )
476 if (OrigMI) cerr << "For MInst:\n " << *OrigMI;
477 cerr << msg << "APPENDed instr:\n " << **AdIt << "\n";
479 InsertAfter(*AdIt, MBB, MII);
485 void PhyRegAlloc::updateMachineCode() {
486 // Insert any instructions needed at method entry
487 MachineBasicBlock::iterator MII = MF.front().begin();
488 PrependInstructions(AddedInstrAtEntry.InstrnsBefore, MF.front(), MII,
489 "At function entry: \n");
490 assert(AddedInstrAtEntry.InstrnsAfter.empty() &&
491 "InstrsAfter should be unnecessary since we are just inserting at "
492 "the function entry point here.");
494 for (MachineFunction::iterator BBI = MF.begin(), BBE = MF.end();
497 // iterate over all the machine instructions in BB
498 MachineBasicBlock &MBB = *BBI;
499 for (MachineBasicBlock::iterator MII = MBB.begin();
500 MII != MBB.end(); ++MII) {
502 MachineInstr *MInst = *MII;
503 unsigned Opcode = MInst->getOpCode();
505 // do not process Phis
506 if (TM.getInstrInfo().isDummyPhiInstr(Opcode))
509 // Reset tmp stack positions so they can be reused for each machine instr.
510 MF.popAllTempValues(TM);
512 // Now insert speical instructions (if necessary) for call/return
515 if (TM.getInstrInfo().isCall(Opcode) ||
516 TM.getInstrInfo().isReturn(Opcode)) {
517 AddedInstrns &AI = AddedInstrMap[MInst];
519 if (TM.getInstrInfo().isCall(Opcode))
520 MRI.colorCallArgs(MInst, LRI, &AI, *this, MBB.getBasicBlock());
521 else if (TM.getInstrInfo().isReturn(Opcode))
522 MRI.colorRetValue(MInst, LRI, &AI);
525 // Set the registers for operands in the machine instruction
526 // if a register was successfully allocated. If not, insert
527 // code to spill the register value.
529 for (unsigned OpNum=0; OpNum < MInst->getNumOperands(); ++OpNum)
531 MachineOperand& Op = MInst->getOperand(OpNum);
532 if (Op.getType() == MachineOperand::MO_VirtualRegister ||
533 Op.getType() == MachineOperand::MO_CCRegister)
535 const Value *const Val = Op.getVRegValue();
537 LiveRange *const LR = LRI.getLiveRangeForValue(Val);
538 if (!LR) // consts or labels will have no live range
540 // if register is not allocated, mark register as invalid
541 if (Op.getAllocatedRegNum() == -1)
542 MInst->SetRegForOperand(OpNum, MRI.getInvalidRegNum());
547 MInst->SetRegForOperand(OpNum,
548 MRI.getUnifiedRegNum(LR->getRegClass()->getID(),
551 // LR did NOT receive a color (register). Insert spill code.
552 insertCode4SpilledLR(LR, MInst, MBB.getBasicBlock(), OpNum);
554 } // for each operand
556 // Now add instructions that the register allocator inserts before/after
557 // this machine instructions (done only for calls/rets/incoming args)
558 // We do this here, to ensure that spill for an instruction is inserted
559 // closest as possible to an instruction (see above insertCode4Spill...)
561 // First, if the instruction in the delay slot of a branch needs
562 // instructions inserted, move it out of the delay slot and before the
563 // branch because putting code before or after it would be VERY BAD!
565 unsigned bumpIteratorBy = 0;
566 if (MII != MBB.begin())
567 if (unsigned predDelaySlots =
568 TM.getInstrInfo().getNumDelaySlots((*(MII-1))->getOpCode()))
570 assert(predDelaySlots==1 && "Not handling multiple delay slots!");
571 if (TM.getInstrInfo().isBranch((*(MII-1))->getOpCode())
572 && (AddedInstrMap.count(MInst) ||
573 AddedInstrMap[MInst].InstrnsAfter.size() > 0))
575 // Current instruction is in the delay slot of a branch and it
576 // needs spill code inserted before or after it.
577 // Move it before the preceding branch.
578 InsertBefore(MInst, MBB, --MII);
580 new MachineInstr(TM.getInstrInfo().getNOPOpCode());
581 SubstituteInPlace(nopI, MBB, MII+1); // replace orig with NOP
582 --MII; // point to MInst in new location
583 bumpIteratorBy = 2; // later skip the branch and the NOP!
587 // If there are instructions to be added, *before* this machine
588 // instruction, add them now.
590 if (AddedInstrMap.count(MInst)) {
591 PrependInstructions(AddedInstrMap[MInst].InstrnsBefore, MBB, MII,"");
594 // If there are instructions to be added *after* this machine
595 // instruction, add them now
597 if (!AddedInstrMap[MInst].InstrnsAfter.empty()) {
599 // if there are delay slots for this instruction, the instructions
600 // added after it must really go after the delayed instruction(s)
601 // So, we move the InstrAfter of the current instruction to the
602 // corresponding delayed instruction
604 TM.getInstrInfo().getNumDelaySlots(MInst->getOpCode())) {
606 // Delayed instructions are typically branches or calls. Let's make
607 // sure this is not a branch, otherwise "insert-after" is meaningless,
608 // and should never happen for any reason (spill code, register
610 assert(! TM.getInstrInfo().isBranch(MInst->getOpCode()) &&
611 ! TM.getInstrInfo().isReturn(MInst->getOpCode()) &&
612 "INTERNAL ERROR: Register allocator should not be inserting "
613 "any code after a branch or return!");
615 move2DelayedInstr(MInst, *(MII+delay) );
618 // Here we can add the "instructions after" to the current
619 // instruction since there are no delay slots for this instruction
620 AppendInstructions(AddedInstrMap[MInst].InstrnsAfter, MBB, MII,"");
624 // If we mucked with the instruction order above, adjust the loop iterator
626 MII = MII + bumpIteratorBy;
628 } // for each machine instruction
634 //----------------------------------------------------------------------------
635 // This method inserts spill code for AN operand whose LR was spilled.
636 // This method may be called several times for a single machine instruction
637 // if it contains many spilled operands. Each time it is called, it finds
638 // a register which is not live at that instruction and also which is not
639 // used by other spilled operands of the same instruction. Then it uses
640 // this register temporarily to accomodate the spilled value.
641 //----------------------------------------------------------------------------
642 void PhyRegAlloc::insertCode4SpilledLR(const LiveRange *LR,
644 const BasicBlock *BB,
645 const unsigned OpNum) {
647 assert((! TM.getInstrInfo().isCall(MInst->getOpCode()) || OpNum == 0) &&
648 "Outgoing arg of a call must be handled elsewhere (func arg ok)");
649 assert(! TM.getInstrInfo().isReturn(MInst->getOpCode()) &&
650 "Return value of a ret must be handled elsewhere");
652 MachineOperand& Op = MInst->getOperand(OpNum);
653 bool isDef = MInst->operandIsDefined(OpNum);
654 bool isDefAndUse = MInst->operandIsDefinedAndUsed(OpNum);
655 unsigned RegType = MRI.getRegType( LR );
656 int SpillOff = LR->getSpillOffFromFP();
657 RegClass *RC = LR->getRegClass();
658 const ValueSet &LVSetBef = LVI->getLiveVarSetBeforeMInst(MInst, BB);
660 MF.pushTempValue(TM, MRI.getSpilledRegSize(RegType) );
662 vector<MachineInstr*> MIBef, MIAft;
663 vector<MachineInstr*> AdIMid;
665 // Choose a register to hold the spilled value. This may insert code
666 // before and after MInst to free up the value. If so, this code should
667 // be first and last in the spill sequence before/after MInst.
668 int TmpRegU = getUsableUniRegAtMI(RegType, &LVSetBef, MInst, MIBef, MIAft);
670 // Set the operand first so that it this register does not get used
671 // as a scratch register for later calls to getUsableUniRegAtMI below
672 MInst->SetRegForOperand(OpNum, TmpRegU);
674 // get the added instructions for this instruction
675 AddedInstrns &AI = AddedInstrMap[MInst];
677 // We may need a scratch register to copy the spilled value to/from memory.
678 // This may itself have to insert code to free up a scratch register.
679 // Any such code should go before (after) the spill code for a load (store).
680 int scratchRegType = -1;
682 if (MRI.regTypeNeedsScratchReg(RegType, scratchRegType))
684 scratchReg = getUsableUniRegAtMI(scratchRegType, &LVSetBef,
685 MInst, MIBef, MIAft);
686 assert(scratchReg != MRI.getInvalidRegNum());
687 MInst->insertUsedReg(scratchReg);
690 if (!isDef || isDefAndUse) {
691 // for a USE, we have to load the value of LR from stack to a TmpReg
692 // and use the TmpReg as one operand of instruction
694 // actual loading instruction(s)
695 MRI.cpMem2RegMI(AdIMid, MRI.getFramePointer(), SpillOff, TmpRegU, RegType,
698 // the actual load should be after the instructions to free up TmpRegU
699 MIBef.insert(MIBef.end(), AdIMid.begin(), AdIMid.end());
703 if (isDef) { // if this is a Def
704 // for a DEF, we have to store the value produced by this instruction
705 // on the stack position allocated for this LR
707 // actual storing instruction(s)
708 MRI.cpReg2MemMI(AdIMid, TmpRegU, MRI.getFramePointer(), SpillOff, RegType,
711 MIAft.insert(MIAft.begin(), AdIMid.begin(), AdIMid.end());
714 // Finally, insert the entire spill code sequences before/after MInst
715 AI.InstrnsBefore.insert(AI.InstrnsBefore.end(), MIBef.begin(), MIBef.end());
716 AI.InstrnsAfter.insert(AI.InstrnsAfter.begin(), MIAft.begin(), MIAft.end());
719 cerr << "\nFor Inst:\n " << *MInst;
720 cerr << "SPILLED LR# " << LR->getUserIGNode()->getIndex();
721 cerr << "; added Instructions:";
722 for_each(MIBef.begin(), MIBef.end(), std::mem_fun(&MachineInstr::dump));
723 for_each(MIAft.begin(), MIAft.end(), std::mem_fun(&MachineInstr::dump));
728 //----------------------------------------------------------------------------
729 // We can use the following method to get a temporary register to be used
730 // BEFORE any given machine instruction. If there is a register available,
731 // this method will simply return that register and set MIBef = MIAft = NULL.
732 // Otherwise, it will return a register and MIAft and MIBef will contain
733 // two instructions used to free up this returned register.
734 // Returned register number is the UNIFIED register number
735 //----------------------------------------------------------------------------
737 int PhyRegAlloc::getUsableUniRegAtMI(const int RegType,
738 const ValueSet *LVSetBef,
740 std::vector<MachineInstr*>& MIBef,
741 std::vector<MachineInstr*>& MIAft) {
743 RegClass* RC = getRegClassByID(MRI.getRegClassIDOfRegType(RegType));
745 int RegU = getUnusedUniRegAtMI(RC, MInst, LVSetBef);
748 // we couldn't find an unused register. Generate code to free up a reg by
749 // saving it on stack and restoring after the instruction
751 int TmpOff = MF.pushTempValue(TM, MRI.getSpilledRegSize(RegType) );
753 RegU = getUniRegNotUsedByThisInst(RC, MInst);
755 // Check if we need a scratch register to copy this register to memory.
756 int scratchRegType = -1;
757 if (MRI.regTypeNeedsScratchReg(RegType, scratchRegType))
759 int scratchReg = getUsableUniRegAtMI(scratchRegType, LVSetBef,
760 MInst, MIBef, MIAft);
761 assert(scratchReg != MRI.getInvalidRegNum());
763 // We may as well hold the value in the scratch register instead
764 // of copying it to memory and back. But we have to mark the
765 // register as used by this instruction, so it does not get used
766 // as a scratch reg. by another operand or anyone else.
767 MInst->insertUsedReg(scratchReg);
768 MRI.cpReg2RegMI(MIBef, RegU, scratchReg, RegType);
769 MRI.cpReg2RegMI(MIAft, scratchReg, RegU, RegType);
772 { // the register can be copied directly to/from memory so do it.
773 MRI.cpReg2MemMI(MIBef, RegU, MRI.getFramePointer(), TmpOff, RegType);
774 MRI.cpMem2RegMI(MIAft, MRI.getFramePointer(), TmpOff, RegU, RegType);
781 //----------------------------------------------------------------------------
782 // This method is called to get a new unused register that can be used to
783 // accomodate a spilled value.
784 // This method may be called several times for a single machine instruction
785 // if it contains many spilled operands. Each time it is called, it finds
786 // a register which is not live at that instruction and also which is not
787 // used by other spilled operands of the same instruction.
788 // Return register number is relative to the register class. NOT
790 //----------------------------------------------------------------------------
791 int PhyRegAlloc::getUnusedUniRegAtMI(RegClass *RC,
792 const MachineInstr *MInst,
793 const ValueSet *LVSetBef) {
795 unsigned NumAvailRegs = RC->getNumOfAvailRegs();
797 std::vector<bool> &IsColorUsedArr = RC->getIsColorUsedArr();
799 for (unsigned i=0; i < NumAvailRegs; i++) // Reset array
800 IsColorUsedArr[i] = false;
802 ValueSet::const_iterator LIt = LVSetBef->begin();
804 // for each live var in live variable set after machine inst
805 for ( ; LIt != LVSetBef->end(); ++LIt) {
807 // get the live range corresponding to live var
808 LiveRange *const LRofLV = LRI.getLiveRangeForValue(*LIt );
810 // LR can be null if it is a const since a const
811 // doesn't have a dominating def - see Assumptions above
812 if (LRofLV && LRofLV->getRegClass() == RC && LRofLV->hasColor() )
813 IsColorUsedArr[ LRofLV->getColor() ] = true;
816 // It is possible that one operand of this MInst was already spilled
817 // and it received some register temporarily. If that's the case,
818 // it is recorded in machine operand. We must skip such registers.
820 setRelRegsUsedByThisInst(RC, MInst);
822 for (unsigned c=0; c < NumAvailRegs; c++) // find first unused color
823 if (!IsColorUsedArr[c])
824 return MRI.getUnifiedRegNum(RC->getID(), c);
830 //----------------------------------------------------------------------------
831 // Get any other register in a register class, other than what is used
832 // by operands of a machine instruction. Returns the unified reg number.
833 //----------------------------------------------------------------------------
834 int PhyRegAlloc::getUniRegNotUsedByThisInst(RegClass *RC,
835 const MachineInstr *MInst) {
837 vector<bool> &IsColorUsedArr = RC->getIsColorUsedArr();
838 unsigned NumAvailRegs = RC->getNumOfAvailRegs();
840 for (unsigned i=0; i < NumAvailRegs ; i++) // Reset array
841 IsColorUsedArr[i] = false;
843 setRelRegsUsedByThisInst(RC, MInst);
845 for (unsigned c=0; c < RC->getNumOfAvailRegs(); c++)// find first unused color
846 if (!IsColorUsedArr[c])
847 return MRI.getUnifiedRegNum(RC->getID(), c);
849 assert(0 && "FATAL: No free register could be found in reg class!!");
854 //----------------------------------------------------------------------------
855 // This method modifies the IsColorUsedArr of the register class passed to it.
856 // It sets the bits corresponding to the registers used by this machine
857 // instructions. Both explicit and implicit operands are set.
858 //----------------------------------------------------------------------------
859 void PhyRegAlloc::setRelRegsUsedByThisInst(RegClass *RC,
860 const MachineInstr *MInst ) {
862 vector<bool> &IsColorUsedArr = RC->getIsColorUsedArr();
864 // Add the registers already marked as used by the instruction.
865 // This should include any scratch registers that are used to save
866 // values across the instruction (e.g., for saving state register values).
867 const vector<bool> ®sUsed = MInst->getRegsUsed();
868 for (unsigned i = 0, e = regsUsed.size(); i != e; ++i)
870 unsigned classId = 0;
871 int classRegNum = MRI.getClassRegNum(i, classId);
872 if (RC->getID() == classId)
874 assert(classRegNum < (int) IsColorUsedArr.size() &&
875 "Illegal register number for this reg class?");
876 IsColorUsedArr[classRegNum] = true;
880 // Now add registers allocated to the live ranges of values used in
881 // the instruction. These are not yet recorded in the instruction.
882 for (unsigned OpNum=0; OpNum < MInst->getNumOperands(); ++OpNum)
884 const MachineOperand& Op = MInst->getOperand(OpNum);
886 if (MInst->getOperandType(OpNum) == MachineOperand::MO_VirtualRegister ||
887 MInst->getOperandType(OpNum) == MachineOperand::MO_CCRegister)
888 if (const Value* Val = Op.getVRegValue())
889 if (MRI.getRegClassIDOfValue(Val) == RC->getID())
890 if (Op.getAllocatedRegNum() == -1)
891 if (LiveRange *LROfVal = LRI.getLiveRangeForValue(Val))
892 if (LROfVal->hasColor() )
893 // this operand is in a LR that received a color
894 IsColorUsedArr[LROfVal->getColor()] = true;
897 // If there are implicit references, mark their allocated regs as well
899 for (unsigned z=0; z < MInst->getNumImplicitRefs(); z++)
901 LRofImpRef = LRI.getLiveRangeForValue(MInst->getImplicitRef(z)))
902 if (LRofImpRef->hasColor())
903 // this implicit reference is in a LR that received a color
904 IsColorUsedArr[LRofImpRef->getColor()] = true;
908 //----------------------------------------------------------------------------
909 // If there are delay slots for an instruction, the instructions
910 // added after it must really go after the delayed instruction(s).
911 // So, we move the InstrAfter of that instruction to the
912 // corresponding delayed instruction using the following method.
914 //----------------------------------------------------------------------------
915 void PhyRegAlloc::move2DelayedInstr(const MachineInstr *OrigMI,
916 const MachineInstr *DelayedMI) {
918 // "added after" instructions of the original instr
919 std::vector<MachineInstr *> &OrigAft = AddedInstrMap[OrigMI].InstrnsAfter;
921 // "added instructions" of the delayed instr
922 AddedInstrns &DelayAdI = AddedInstrMap[DelayedMI];
924 // "added after" instructions of the delayed instr
925 std::vector<MachineInstr *> &DelayedAft = DelayAdI.InstrnsAfter;
927 // go thru all the "added after instructions" of the original instruction
928 // and append them to the "addded after instructions" of the delayed
930 DelayedAft.insert(DelayedAft.end(), OrigAft.begin(), OrigAft.end());
932 // empty the "added after instructions" of the original instruction
936 //----------------------------------------------------------------------------
937 // This method prints the code with registers after register allocation is
939 //----------------------------------------------------------------------------
940 void PhyRegAlloc::printMachineCode()
943 cerr << "\n;************** Function " << Fn->getName()
944 << " *****************\n";
946 for (MachineFunction::iterator BBI = MF.begin(), BBE = MF.end();
948 cerr << "\n"; printLabel(BBI->getBasicBlock()); cerr << ": ";
950 // get the iterator for machine instructions
951 MachineBasicBlock& MBB = *BBI;
952 MachineBasicBlock::iterator MII = MBB.begin();
954 // iterate over all the machine instructions in BB
955 for ( ; MII != MBB.end(); ++MII) {
956 MachineInstr *const MInst = *MII;
959 cerr << TargetInstrDescriptors[MInst->getOpCode()].opCodeString;
961 for (unsigned OpNum=0; OpNum < MInst->getNumOperands(); ++OpNum) {
962 MachineOperand& Op = MInst->getOperand(OpNum);
964 if (Op.getType() == MachineOperand::MO_VirtualRegister ||
965 Op.getType() == MachineOperand::MO_CCRegister /*||
966 Op.getType() == MachineOperand::MO_PCRelativeDisp*/ ) {
968 const Value *const Val = Op.getVRegValue () ;
969 // ****this code is temporary till NULL Values are fixed
971 cerr << "\t<*NULL*>";
975 // if a label or a constant
976 if (isa<BasicBlock>(Val)) {
977 cerr << "\t"; printLabel( Op.getVRegValue () );
979 // else it must be a register value
980 const int RegNum = Op.getAllocatedRegNum();
982 cerr << "\t" << "%" << MRI.getUnifiedRegName( RegNum );
984 cerr << "(" << Val->getName() << ")";
986 cerr << "(" << Val << ")";
991 const LiveRange *LROfVal = LRI.getLiveRangeForValue(Val);
993 if (LROfVal->hasSpillOffset() )
998 else if (Op.getType() == MachineOperand::MO_MachineRegister) {
999 cerr << "\t" << "%" << MRI.getUnifiedRegName(Op.getMachineRegNum());
1003 cerr << "\t" << Op; // use dump field
1008 unsigned NumOfImpRefs = MInst->getNumImplicitRefs();
1009 if (NumOfImpRefs > 0) {
1010 cerr << "\tImplicit:";
1012 for (unsigned z=0; z < NumOfImpRefs; z++)
1013 cerr << RAV(MInst->getImplicitRef(z)) << "\t";
1016 } // for all machine instructions
1026 //----------------------------------------------------------------------------
1028 //----------------------------------------------------------------------------
1029 void PhyRegAlloc::colorIncomingArgs()
1031 MRI.colorMethodArgs(Fn, LRI, &AddedInstrAtEntry);
1035 //----------------------------------------------------------------------------
1036 // Used to generate a label for a basic block
1037 //----------------------------------------------------------------------------
1038 void PhyRegAlloc::printLabel(const Value *Val) {
1040 cerr << Val->getName();
1042 cerr << "Label" << Val;
1046 //----------------------------------------------------------------------------
1047 // This method calls setSugColorUsable method of each live range. This
1048 // will determine whether the suggested color of LR is really usable.
1049 // A suggested color is not usable when the suggested color is volatile
1050 // AND when there are call interferences
1051 //----------------------------------------------------------------------------
1053 void PhyRegAlloc::markUnusableSugColors()
1055 // hash map iterator
1056 LiveRangeMapType::const_iterator HMI = (LRI.getLiveRangeMap())->begin();
1057 LiveRangeMapType::const_iterator HMIEnd = (LRI.getLiveRangeMap())->end();
1059 for (; HMI != HMIEnd ; ++HMI ) {
1061 LiveRange *L = HMI->second; // get the LiveRange
1063 if (L->hasSuggestedColor()) {
1064 int RCID = L->getRegClass()->getID();
1065 if (MRI.isRegVolatile( RCID, L->getSuggestedColor()) &&
1066 L->isCallInterference() )
1067 L->setSuggestedColorUsable( false );
1069 L->setSuggestedColorUsable( true );
1071 } // if L->hasSuggestedColor()
1073 } // for all LR's in hash map
1078 //----------------------------------------------------------------------------
1079 // The following method will set the stack offsets of the live ranges that
1080 // are decided to be spillled. This must be called just after coloring the
1081 // LRs using the graph coloring algo. For each live range that is spilled,
1082 // this method allocate a new spill position on the stack.
1083 //----------------------------------------------------------------------------
1085 void PhyRegAlloc::allocateStackSpace4SpilledLRs() {
1086 if (DEBUG_RA) cerr << "\nSetting LR stack offsets for spills...\n";
1088 LiveRangeMapType::const_iterator HMI = LRI.getLiveRangeMap()->begin();
1089 LiveRangeMapType::const_iterator HMIEnd = LRI.getLiveRangeMap()->end();
1091 for ( ; HMI != HMIEnd ; ++HMI) {
1092 if (HMI->first && HMI->second) {
1093 LiveRange *L = HMI->second; // get the LiveRange
1094 if (!L->hasColor()) { // NOTE: ** allocating the size of long Type **
1095 int stackOffset = MF.allocateSpilledValue(TM, Type::LongTy);
1096 L->setSpillOffFromFP(stackOffset);
1098 cerr << " LR# " << L->getUserIGNode()->getIndex()
1099 << ": stack-offset = " << stackOffset << "\n";
1102 } // for all LR's in hash map
1107 //----------------------------------------------------------------------------
1108 // The entry pont to Register Allocation
1109 //----------------------------------------------------------------------------
1111 void PhyRegAlloc::allocateRegisters()
1114 // make sure that we put all register classes into the RegClassList
1115 // before we call constructLiveRanges (now done in the constructor of
1116 // PhyRegAlloc class).
1118 LRI.constructLiveRanges(); // create LR info
1120 if (DEBUG_RA >= RA_DEBUG_LiveRanges)
1121 LRI.printLiveRanges();
1123 createIGNodeListsAndIGs(); // create IGNode list and IGs
1125 buildInterferenceGraphs(); // build IGs in all reg classes
1128 if (DEBUG_RA >= RA_DEBUG_LiveRanges) {
1129 // print all LRs in all reg classes
1130 for ( unsigned rc=0; rc < NumOfRegClasses ; rc++)
1131 RegClassList[rc]->printIGNodeList();
1133 // print IGs in all register classes
1134 for ( unsigned rc=0; rc < NumOfRegClasses ; rc++)
1135 RegClassList[rc]->printIG();
1138 LRI.coalesceLRs(); // coalesce all live ranges
1140 if (DEBUG_RA >= RA_DEBUG_LiveRanges) {
1141 // print all LRs in all reg classes
1142 for (unsigned rc=0; rc < NumOfRegClasses; rc++)
1143 RegClassList[rc]->printIGNodeList();
1145 // print IGs in all register classes
1146 for (unsigned rc=0; rc < NumOfRegClasses; rc++)
1147 RegClassList[rc]->printIG();
1151 // mark un-usable suggested color before graph coloring algorithm.
1152 // When this is done, the graph coloring algo will not reserve
1153 // suggested color unnecessarily - they can be used by another LR
1155 markUnusableSugColors();
1157 // color all register classes using the graph coloring algo
1158 for (unsigned rc=0; rc < NumOfRegClasses ; rc++)
1159 RegClassList[rc]->colorAllRegs();
1161 // Atter grpah coloring, if some LRs did not receive a color (i.e, spilled)
1162 // a poistion for such spilled LRs
1164 allocateStackSpace4SpilledLRs();
1166 MF.popAllTempValues(TM); // TODO **Check
1168 // color incoming args - if the correct color was not received
1169 // insert code to copy to the correct register
1171 colorIncomingArgs();
1173 // Now update the machine code with register names and add any
1174 // additional code inserted by the register allocator to the instruction
1177 updateMachineCode();
1180 cerr << "\n**** Machine Code After Register Allocation:\n\n";