1 //===-- RegisterPressure.cpp - Dynamic Register Pressure ------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the RegisterPressure class which can be used to track
11 // MachineInstr level register pressure.
13 //===----------------------------------------------------------------------===//
15 #include "RegisterClassInfo.h"
16 #include "RegisterPressure.h"
17 #include "llvm/CodeGen/LiveInterval.h"
18 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
19 #include "llvm/CodeGen/MachineRegisterInfo.h"
20 #include "llvm/Target/TargetMachine.h"
24 /// Increase register pressure for each set impacted by this register class.
25 static void increaseSetPressure(std::vector<unsigned> &CurrSetPressure,
26 std::vector<unsigned> &MaxSetPressure,
27 const TargetRegisterClass *RC,
28 const TargetRegisterInfo *TRI) {
29 unsigned Weight = TRI->getRegClassWeight(RC).RegWeight;
30 for (const int *PSet = TRI->getRegClassPressureSets(RC);
31 *PSet != -1; ++PSet) {
32 CurrSetPressure[*PSet] += Weight;
33 if (&CurrSetPressure != &MaxSetPressure
34 && CurrSetPressure[*PSet] > MaxSetPressure[*PSet]) {
35 MaxSetPressure[*PSet] = CurrSetPressure[*PSet];
40 /// Decrease register pressure for each set impacted by this register class.
41 static void decreaseSetPressure(std::vector<unsigned> &CurrSetPressure,
42 const TargetRegisterClass *RC,
43 const TargetRegisterInfo *TRI) {
44 unsigned Weight = TRI->getRegClassWeight(RC).RegWeight;
45 for (const int *PSet = TRI->getRegClassPressureSets(RC);
46 *PSet != -1; ++PSet) {
47 assert(CurrSetPressure[*PSet] >= Weight && "register pressure underflow");
48 CurrSetPressure[*PSet] -= Weight;
52 /// Directly increase pressure only within this RegisterPressure result.
53 void RegisterPressure::increase(const TargetRegisterClass *RC,
54 const TargetRegisterInfo *TRI) {
55 increaseSetPressure(MaxSetPressure, MaxSetPressure, RC, TRI);
58 /// Directly decrease pressure only within this RegisterPressure result.
59 void RegisterPressure::decrease(const TargetRegisterClass *RC,
60 const TargetRegisterInfo *TRI) {
61 decreaseSetPressure(MaxSetPressure, RC, TRI);
64 /// Increase the current pressure as impacted by these physical registers and
65 /// bump the high water mark if needed.
66 void RegPressureTracker::increasePhysRegPressure(ArrayRef<unsigned> Regs) {
67 for (unsigned I = 0, E = Regs.size(); I != E; ++I)
68 increaseSetPressure(CurrSetPressure, P.MaxSetPressure,
69 TRI->getMinimalPhysRegClass(Regs[I]), TRI);
72 /// Simply decrease the current pressure as impacted by these physcial
74 void RegPressureTracker::decreasePhysRegPressure(ArrayRef<unsigned> Regs) {
75 for (unsigned I = 0, E = Regs.size(); I != E; ++I)
76 decreaseSetPressure(CurrSetPressure, TRI->getMinimalPhysRegClass(Regs[I]),
80 /// Increase the current pressure as impacted by these virtual registers and
81 /// bump the high water mark if needed.
82 void RegPressureTracker::increaseVirtRegPressure(ArrayRef<unsigned> Regs) {
83 for (unsigned I = 0, E = Regs.size(); I != E; ++I)
84 increaseSetPressure(CurrSetPressure, P.MaxSetPressure,
85 MRI->getRegClass(Regs[I]), TRI);
88 /// Simply decrease the current pressure as impacted by these virtual registers.
89 void RegPressureTracker::decreaseVirtRegPressure(ArrayRef<unsigned> Regs) {
90 for (unsigned I = 0, E = Regs.size(); I != E; ++I)
91 decreaseSetPressure(CurrSetPressure, MRI->getRegClass(Regs[I]), TRI);
94 /// Clear the result so it can be used for another round of pressure tracking.
95 void IntervalPressure::reset() {
96 TopIdx = BottomIdx = SlotIndex();
97 MaxSetPressure.clear();
102 /// Clear the result so it can be used for another round of pressure tracking.
103 void RegionPressure::reset() {
104 TopPos = BottomPos = MachineBasicBlock::const_iterator();
105 MaxSetPressure.clear();
110 /// If the current top is not less than or equal to the next index, open it.
111 /// We happen to need the SlotIndex for the next top for pressure update.
112 void IntervalPressure::openTop(SlotIndex NextTop) {
113 if (TopIdx <= NextTop)
115 TopIdx = SlotIndex();
119 /// If the current top is the previous instruction (before receding), open it.
120 void RegionPressure::openTop(MachineBasicBlock::const_iterator PrevTop) {
121 if (TopPos != PrevTop)
123 TopPos = MachineBasicBlock::const_iterator();
127 /// If the current bottom is not greater than the previous index, open it.
128 void IntervalPressure::openBottom(SlotIndex PrevBottom) {
129 if (BottomIdx > PrevBottom)
131 BottomIdx = SlotIndex();
135 /// If the current bottom is the previous instr (before advancing), open it.
136 void RegionPressure::openBottom(MachineBasicBlock::const_iterator PrevBottom) {
137 if (BottomPos != PrevBottom)
139 BottomPos = MachineBasicBlock::const_iterator();
143 /// Setup the RegPressureTracker.
145 /// TODO: Add support for pressure without LiveIntervals.
146 void RegPressureTracker::init(const MachineFunction *mf,
147 const RegisterClassInfo *rci,
148 const LiveIntervals *lis,
149 const MachineBasicBlock *mbb,
150 MachineBasicBlock::const_iterator pos)
153 TRI = MF->getTarget().getRegisterInfo();
155 MRI = &MF->getRegInfo();
158 if (RequireIntervals) {
159 assert(lis && "IntervalPressure requires LiveIntervals");
164 while (CurrPos != MBB->end() && CurrPos->isDebugValue())
167 CurrSetPressure.assign(TRI->getNumRegPressureSets(), 0);
169 if (RequireIntervals)
170 static_cast<IntervalPressure&>(P).reset();
172 static_cast<RegionPressure&>(P).reset();
173 P.MaxSetPressure = CurrSetPressure;
175 LivePhysRegs.clear();
176 LivePhysRegs.setUniverse(TRI->getNumRegs());
177 LiveVirtRegs.clear();
178 LiveVirtRegs.setUniverse(MRI->getNumVirtRegs());
181 /// Does this pressure result have a valid top position and live ins.
182 bool RegPressureTracker::isTopClosed() const {
183 if (RequireIntervals)
184 return static_cast<IntervalPressure&>(P).TopIdx.isValid();
185 return (static_cast<RegionPressure&>(P).TopPos ==
186 MachineBasicBlock::const_iterator());
189 /// Does this pressure result have a valid bottom position and live outs.
190 bool RegPressureTracker::isBottomClosed() const {
191 if (RequireIntervals)
192 return static_cast<IntervalPressure&>(P).BottomIdx.isValid();
193 return (static_cast<RegionPressure&>(P).BottomPos ==
194 MachineBasicBlock::const_iterator());
197 /// Set the boundary for the top of the region and summarize live ins.
198 void RegPressureTracker::closeTop() {
199 if (RequireIntervals)
200 static_cast<IntervalPressure&>(P).TopIdx =
201 LIS->getInstructionIndex(CurrPos).getRegSlot();
203 static_cast<RegionPressure&>(P).TopPos = CurrPos;
205 assert(P.LiveInRegs.empty() && "inconsistent max pressure result");
206 P.LiveInRegs.reserve(LivePhysRegs.size() + LiveVirtRegs.size());
207 P.LiveInRegs.append(LivePhysRegs.begin(), LivePhysRegs.end());
208 for (SparseSet<unsigned>::const_iterator I =
209 LiveVirtRegs.begin(), E = LiveVirtRegs.end(); I != E; ++I)
210 P.LiveInRegs.push_back(*I);
211 std::sort(P.LiveInRegs.begin(), P.LiveInRegs.end());
212 P.LiveInRegs.erase(std::unique(P.LiveInRegs.begin(), P.LiveInRegs.end()),
216 /// Set the boundary for the bottom of the region and summarize live outs.
217 void RegPressureTracker::closeBottom() {
218 if (RequireIntervals)
219 if (CurrPos == MBB->end())
220 static_cast<IntervalPressure&>(P).BottomIdx = LIS->getMBBEndIdx(MBB);
222 static_cast<IntervalPressure&>(P).BottomIdx =
223 LIS->getInstructionIndex(CurrPos).getRegSlot();
225 static_cast<RegionPressure&>(P).BottomPos = CurrPos;
227 assert(P.LiveOutRegs.empty() && "inconsistent max pressure result");
228 P.LiveOutRegs.reserve(LivePhysRegs.size() + LiveVirtRegs.size());
229 P.LiveOutRegs.append(LivePhysRegs.begin(), LivePhysRegs.end());
230 for (SparseSet<unsigned>::const_iterator I =
231 LiveVirtRegs.begin(), E = LiveVirtRegs.end(); I != E; ++I)
232 P.LiveOutRegs.push_back(*I);
233 std::sort(P.LiveOutRegs.begin(), P.LiveOutRegs.end());
234 P.LiveOutRegs.erase(std::unique(P.LiveOutRegs.begin(), P.LiveOutRegs.end()),
235 P.LiveOutRegs.end());
238 /// Finalize the region boundaries and record live ins and live outs.
239 void RegPressureTracker::closeRegion() {
240 if (!isTopClosed() && !isBottomClosed()) {
241 assert(LivePhysRegs.empty() && LiveVirtRegs.empty() &&
242 "no region boundary");
245 if (!isBottomClosed())
247 else if (!isTopClosed())
249 // If both top and bottom are closed, do nothing.
252 /// Return true if Reg aliases a register in Regs SparseSet.
253 static bool hasRegAlias(unsigned Reg, SparseSet<unsigned> &Regs,
254 const TargetRegisterInfo *TRI) {
255 assert(!TargetRegisterInfo::isVirtualRegister(Reg) && "only for physregs");
256 for (const uint16_t *Alias = TRI->getOverlaps(Reg); *Alias; ++Alias) {
257 if (Regs.count(*Alias))
263 /// Return true if Reg aliases a register in unsorted Regs SmallVector.
264 /// This is only valid for physical registers.
265 static SmallVectorImpl<unsigned>::iterator
266 findRegAlias(unsigned Reg, SmallVectorImpl<unsigned> &Regs,
267 const TargetRegisterInfo *TRI) {
268 for (const uint16_t *Alias = TRI->getOverlaps(Reg); *Alias; ++Alias) {
269 SmallVectorImpl<unsigned>::iterator I =
270 std::find(Regs.begin(), Regs.end(), *Alias);
277 /// Return true if Reg can be inserted into Regs SmallVector. For virtual
278 /// register, do a linear search. For physical registers check for aliases.
279 static SmallVectorImpl<unsigned>::iterator
280 findReg(unsigned Reg, bool isVReg, SmallVectorImpl<unsigned> &Regs,
281 const TargetRegisterInfo *TRI) {
283 return std::find(Regs.begin(), Regs.end(), Reg);
284 return findRegAlias(Reg, Regs, TRI);
287 /// Collect this instruction's unique uses and defs into SmallVectors for
288 /// processing defs and uses in order.
289 template<bool isVReg>
290 struct RegisterOperands {
291 SmallVector<unsigned, 8> Uses;
292 SmallVector<unsigned, 8> Defs;
293 SmallVector<unsigned, 8> DeadDefs;
295 /// Push this operand's register onto the correct vector.
296 void collect(const MachineOperand &MO, const TargetRegisterInfo *TRI) {
298 if (findReg(MO.getReg(), isVReg, Uses, TRI) == Uses.end())
299 Uses.push_back(MO.getReg());
303 if (findReg(MO.getReg(), isVReg, DeadDefs, TRI) == DeadDefs.end())
304 DeadDefs.push_back(MO.getReg());
307 if (findReg(MO.getReg(), isVReg, Defs, TRI) == Defs.end())
308 Defs.push_back(MO.getReg());
313 typedef RegisterOperands<false> PhysRegOperands;
314 typedef RegisterOperands<true> VirtRegOperands;
316 /// Collect physical and virtual register operands.
317 static void collectOperands(const MachineInstr *MI,
318 PhysRegOperands &PhysRegOpers,
319 VirtRegOperands &VirtRegOpers,
320 const TargetRegisterInfo *TRI,
321 const RegisterClassInfo *RCI) {
322 for(ConstMIBundleOperands OperI(MI); OperI.isValid(); ++OperI) {
323 const MachineOperand &MO = *OperI;
324 if (!MO.isReg() || !MO.getReg())
327 if (TargetRegisterInfo::isVirtualRegister(MO.getReg()))
328 VirtRegOpers.collect(MO, TRI);
329 else if (RCI->isAllocatable(MO.getReg()))
330 PhysRegOpers.collect(MO, TRI);
332 // Remove redundant physreg dead defs.
333 for (unsigned i = PhysRegOpers.DeadDefs.size(); i > 0; --i) {
334 unsigned Reg = PhysRegOpers.DeadDefs[i-1];
335 if (findRegAlias(Reg, PhysRegOpers.Defs, TRI) != PhysRegOpers.Defs.end())
336 PhysRegOpers.DeadDefs.erase(&PhysRegOpers.DeadDefs[i-1]);
340 /// Force liveness of registers.
341 void RegPressureTracker::addLiveRegs(ArrayRef<unsigned> Regs) {
342 for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
343 if (TargetRegisterInfo::isVirtualRegister(Regs[i])) {
344 if (LiveVirtRegs.insert(Regs[i]).second)
345 increaseVirtRegPressure(Regs[i]);
348 if (!hasRegAlias(Regs[i], LivePhysRegs, TRI)) {
349 LivePhysRegs.insert(Regs[i]);
350 increasePhysRegPressure(Regs[i]);
356 /// Add PhysReg to the live in set and increase max pressure.
357 void RegPressureTracker::discoverPhysLiveIn(unsigned Reg) {
358 assert(!LivePhysRegs.count(Reg) && "avoid bumping max pressure twice");
359 if (findRegAlias(Reg, P.LiveInRegs, TRI) == P.LiveInRegs.end())
362 // At live in discovery, unconditionally increase the high water mark.
363 P.LiveInRegs.push_back(Reg);
364 P.increase(TRI->getMinimalPhysRegClass(Reg), TRI);
367 /// Add PhysReg to the live out set and increase max pressure.
368 void RegPressureTracker::discoverPhysLiveOut(unsigned Reg) {
369 assert(!LivePhysRegs.count(Reg) && "avoid bumping max pressure twice");
370 if (findRegAlias(Reg, P.LiveOutRegs, TRI) == P.LiveOutRegs.end())
373 // At live out discovery, unconditionally increase the high water mark.
374 P.LiveOutRegs.push_back(Reg);
375 P.increase(TRI->getMinimalPhysRegClass(Reg), TRI);
378 /// Add VirtReg to the live in set and increase max pressure.
379 void RegPressureTracker::discoverVirtLiveIn(unsigned Reg) {
380 assert(!LiveVirtRegs.count(Reg) && "avoid bumping max pressure twice");
381 if (std::find(P.LiveInRegs.begin(), P.LiveInRegs.end(), Reg) !=
385 // At live in discovery, unconditionally increase the high water mark.
386 P.LiveInRegs.push_back(Reg);
387 P.increase(MRI->getRegClass(Reg), TRI);
390 /// Add VirtReg to the live out set and increase max pressure.
391 void RegPressureTracker::discoverVirtLiveOut(unsigned Reg) {
392 assert(!LiveVirtRegs.count(Reg) && "avoid bumping max pressure twice");
393 if (std::find(P.LiveOutRegs.begin(), P.LiveOutRegs.end(), Reg) !=
397 // At live out discovery, unconditionally increase the high water mark.
398 P.LiveOutRegs.push_back(Reg);
399 P.increase(MRI->getRegClass(Reg), TRI);
402 /// Recede across the previous instruction.
403 bool RegPressureTracker::recede() {
404 // Check for the top of the analyzable region.
405 if (CurrPos == MBB->begin()) {
409 if (!isBottomClosed())
412 // Open the top of the region using block iterators.
413 if (!RequireIntervals && isTopClosed())
414 static_cast<RegionPressure&>(P).openTop(CurrPos);
416 // Find the previous instruction.
419 while (CurrPos != MBB->begin() && CurrPos->isDebugValue());
421 if (CurrPos->isDebugValue()) {
426 if (RequireIntervals)
427 SlotIdx = LIS->getInstructionIndex(CurrPos).getRegSlot();
429 // Open the top of the region using slot indexes.
430 if (RequireIntervals && isTopClosed())
431 static_cast<IntervalPressure&>(P).openTop(SlotIdx);
433 PhysRegOperands PhysRegOpers;
434 VirtRegOperands VirtRegOpers;
435 collectOperands(CurrPos, PhysRegOpers, VirtRegOpers, TRI, RCI);
437 // Boost pressure for all dead defs together.
438 increasePhysRegPressure(PhysRegOpers.DeadDefs);
439 increaseVirtRegPressure(VirtRegOpers.DeadDefs);
440 decreasePhysRegPressure(PhysRegOpers.DeadDefs);
441 decreaseVirtRegPressure(VirtRegOpers.DeadDefs);
443 // Kill liveness at live defs.
444 // TODO: consider earlyclobbers?
445 for (unsigned i = 0, e = PhysRegOpers.Defs.size(); i < e; ++i) {
446 unsigned Reg = PhysRegOpers.Defs[i];
447 if (LivePhysRegs.erase(Reg))
448 decreasePhysRegPressure(Reg);
450 discoverPhysLiveOut(Reg);
452 for (unsigned i = 0, e = VirtRegOpers.Defs.size(); i < e; ++i) {
453 unsigned Reg = VirtRegOpers.Defs[i];
454 if (LiveVirtRegs.erase(Reg))
455 decreaseVirtRegPressure(Reg);
457 discoverVirtLiveOut(Reg);
460 // Generate liveness for uses.
461 for (unsigned i = 0, e = PhysRegOpers.Uses.size(); i < e; ++i) {
462 unsigned Reg = PhysRegOpers.Uses[i];
463 if (!hasRegAlias(Reg, LivePhysRegs, TRI)) {
464 increasePhysRegPressure(Reg);
465 LivePhysRegs.insert(Reg);
468 for (unsigned i = 0, e = VirtRegOpers.Uses.size(); i < e; ++i) {
469 unsigned Reg = VirtRegOpers.Uses[i];
470 if (!LiveVirtRegs.count(Reg)) {
471 // Adjust liveouts if LiveIntervals are available.
472 if (RequireIntervals) {
473 const LiveInterval *LI = &LIS->getInterval(Reg);
474 if (!LI->killedAt(SlotIdx))
475 discoverVirtLiveOut(Reg);
477 increaseVirtRegPressure(Reg);
478 LiveVirtRegs.insert(Reg);
484 /// Advance across the current instruction.
485 bool RegPressureTracker::advance() {
486 // Check for the bottom of the analyzable region.
487 if (CurrPos == MBB->end()) {
495 if (RequireIntervals)
496 SlotIdx = LIS->getInstructionIndex(CurrPos).getRegSlot();
498 // Open the bottom of the region using slot indexes.
499 if (isBottomClosed()) {
500 if (RequireIntervals)
501 static_cast<IntervalPressure&>(P).openBottom(SlotIdx);
503 static_cast<RegionPressure&>(P).openBottom(CurrPos);
506 PhysRegOperands PhysRegOpers;
507 VirtRegOperands VirtRegOpers;
508 collectOperands(CurrPos, PhysRegOpers, VirtRegOpers, TRI, RCI);
510 // Kill liveness at last uses.
511 for (unsigned i = 0, e = PhysRegOpers.Uses.size(); i < e; ++i) {
512 unsigned Reg = PhysRegOpers.Uses[i];
513 if (!hasRegAlias(Reg, LivePhysRegs, TRI))
514 discoverPhysLiveIn(Reg);
516 // Allocatable physregs are always single-use before regalloc.
517 decreasePhysRegPressure(Reg);
518 LivePhysRegs.erase(Reg);
521 for (unsigned i = 0, e = VirtRegOpers.Uses.size(); i < e; ++i) {
522 unsigned Reg = VirtRegOpers.Uses[i];
523 if (RequireIntervals) {
524 const LiveInterval *LI = &LIS->getInterval(Reg);
525 if (LI->killedAt(SlotIdx)) {
526 if (LiveVirtRegs.erase(Reg))
527 decreaseVirtRegPressure(Reg);
529 discoverVirtLiveIn(Reg);
532 else if (!LiveVirtRegs.count(Reg)) {
533 discoverVirtLiveIn(Reg);
534 increaseVirtRegPressure(Reg);
538 // Generate liveness for defs.
539 for (unsigned i = 0, e = PhysRegOpers.Defs.size(); i < e; ++i) {
540 unsigned Reg = PhysRegOpers.Defs[i];
541 if (!hasRegAlias(Reg, LivePhysRegs, TRI)) {
542 increasePhysRegPressure(Reg);
543 LivePhysRegs.insert(Reg);
546 for (unsigned i = 0, e = VirtRegOpers.Defs.size(); i < e; ++i) {
547 unsigned Reg = VirtRegOpers.Defs[i];
548 if (LiveVirtRegs.insert(Reg).second)
549 increaseVirtRegPressure(Reg);
552 // Boost pressure for all dead defs together.
553 increasePhysRegPressure(PhysRegOpers.DeadDefs);
554 increaseVirtRegPressure(VirtRegOpers.DeadDefs);
555 decreasePhysRegPressure(PhysRegOpers.DeadDefs);
556 decreaseVirtRegPressure(VirtRegOpers.DeadDefs);
558 // Find the next instruction.
561 while (CurrPos != MBB->end() && CurrPos->isDebugValue());
565 // Find the max change in excess pressure across all sets.
566 static int computeMaxPressureDelta(ArrayRef<unsigned> OldPressureVec,
567 ArrayRef<unsigned> NewPressureVec,
569 const TargetRegisterInfo *TRI) {
571 for (unsigned i = 0, e = OldPressureVec.size(); i < e; ++i) {
572 unsigned POld = OldPressureVec[i];
573 unsigned PNew = NewPressureVec[i];
574 int PDiff = (int)PNew - (int)POld;
575 if (!PDiff) // No change in this set in the common case.
577 // Only consider change beyond the limit.
578 unsigned Limit = TRI->getRegPressureSetLimit(i);
581 PDiff = 0; // Under the limit
583 PDiff = PNew - Limit; // Just exceeded limit.
585 else if (Limit > PNew)
586 PDiff = Limit - POld; // Just obeyed limit.
588 if (std::abs(PDiff) > std::abs(ExcessUnits)) {
596 /// Consider the pressure increase caused by traversing this instruction
597 /// bottom-up. Find the pressure set with the most change beyond its pressure
598 /// limit based on the tracker's current pressure, and return the change in
599 /// number of register units of that pressure set introduced by this
602 /// This assumes that the current LiveOut set is sufficient.
604 /// FIXME: This is expensive for an on-the-fly query. We need to cache the
605 /// result per-SUnit with enough information to adjust for the current
606 /// scheduling position. But this works as a proof of concept.
607 void RegPressureTracker::
608 getMaxUpwardPressureDelta(const MachineInstr *MI, RegPressureDelta &Delta) {
609 // Account for register pressure similar to RegPressureTracker::recede().
610 PhysRegOperands PhysRegOpers;
611 VirtRegOperands VirtRegOpers;
612 collectOperands(MI, PhysRegOpers, VirtRegOpers, TRI, RCI);
614 // Snapshot Pressure.
615 std::vector<unsigned> SavedPressure = CurrSetPressure;
616 std::vector<unsigned> SavedMaxPressure = P.MaxSetPressure;
618 // Boost max pressure for all dead defs together.
619 // Since CurrSetPressure and MaxSetPressure
620 increasePhysRegPressure(PhysRegOpers.DeadDefs);
621 increaseVirtRegPressure(VirtRegOpers.DeadDefs);
622 decreasePhysRegPressure(PhysRegOpers.DeadDefs);
623 decreaseVirtRegPressure(VirtRegOpers.DeadDefs);
625 // Kill liveness at live defs.
626 decreasePhysRegPressure(PhysRegOpers.Defs);
627 decreaseVirtRegPressure(VirtRegOpers.Defs);
629 // Generate liveness for uses.
630 for (unsigned i = 0, e = PhysRegOpers.Uses.size(); i < e; ++i) {
631 unsigned Reg = PhysRegOpers.Uses[i];
632 if (!hasRegAlias(Reg, LivePhysRegs, TRI)
633 && (findRegAlias(Reg, PhysRegOpers.Defs, TRI)
634 == PhysRegOpers.Defs.end())) {
635 increasePhysRegPressure(Reg);
638 for (unsigned i = 0, e = VirtRegOpers.Uses.size(); i < e; ++i) {
639 unsigned Reg = VirtRegOpers.Uses[i];
640 if (!LiveVirtRegs.count(Reg)
641 && (std::find(VirtRegOpers.Defs.begin(), VirtRegOpers.Defs.end(), Reg)
642 != VirtRegOpers.Defs.end())) {
643 increaseVirtRegPressure(Reg);
647 computeMaxPressureDelta(SavedPressure, CurrSetPressure,
648 Delta.ExcessSetID, TRI);
649 Delta.MaxUnitIncrease =
650 computeMaxPressureDelta(SavedMaxPressure, P.MaxSetPressure,
651 Delta.MaxSetID, TRI);
652 assert(Delta.MaxUnitIncrease >= 0 && "cannot increase max pressure");
654 // Restore the tracker's state.
655 P.MaxSetPressure.swap(SavedMaxPressure);
656 CurrSetPressure.swap(SavedPressure);
659 /// Helper to find a vreg use between two indices [PriorUseIdx, NextUseIdx).
660 static bool findUseBetween(unsigned Reg,
661 SlotIndex PriorUseIdx, SlotIndex NextUseIdx,
662 const MachineRegisterInfo *MRI,
663 const LiveIntervals *LIS) {
664 for (MachineRegisterInfo::use_nodbg_iterator
665 UI = MRI->use_nodbg_begin(Reg), UE = MRI->use_nodbg_end();
666 UI != UE; UI.skipInstruction()) {
667 const MachineInstr* MI = &*UI;
668 SlotIndex InstSlot = LIS->getInstructionIndex(MI).getRegSlot();
669 if (InstSlot >= PriorUseIdx && InstSlot < NextUseIdx)
675 /// Consider the pressure increase caused by traversing this instruction
676 /// top-down. Find the register class with the most change in its pressure limit
677 /// based on the tracker's current pressure, and return the number of excess
678 /// register units of that pressure set introduced by this instruction.
680 /// This assumes that the current LiveIn set is sufficient.
681 void RegPressureTracker::
682 getMaxDownwardPressureDelta(const MachineInstr *MI, RegPressureDelta &Delta) {
683 // Account for register pressure similar to RegPressureTracker::recede().
684 PhysRegOperands PhysRegOpers;
685 VirtRegOperands VirtRegOpers;
686 collectOperands(MI, PhysRegOpers, VirtRegOpers, TRI, RCI);
688 // Snapshot Pressure.
689 std::vector<unsigned> SavedPressure = CurrSetPressure;
690 std::vector<unsigned> SavedMaxPressure = P.MaxSetPressure;
692 // Kill liveness at last uses. Assume allocatable physregs are single-use
693 // rather than checking LiveIntervals.
694 decreasePhysRegPressure(PhysRegOpers.Uses);
695 if (RequireIntervals) {
696 SlotIndex SlotIdx = LIS->getInstructionIndex(MI).getRegSlot();
697 for (unsigned i = 0, e = VirtRegOpers.Uses.size(); i < e; ++i) {
698 unsigned Reg = VirtRegOpers.Uses[i];
699 const LiveInterval *LI = &LIS->getInterval(Reg);
700 // FIXME: allow the caller to pass in the list of vreg uses that remain to
701 // be top-scheduled to avoid searching uses at each query.
702 SlotIndex CurrIdx = LIS->getInstructionIndex(CurrPos).getRegSlot();
703 if (LI->killedAt(SlotIdx)
704 && !findUseBetween(Reg, CurrIdx, SlotIdx, MRI, LIS)) {
705 decreaseVirtRegPressure(Reg);
710 // Generate liveness for defs.
711 increasePhysRegPressure(PhysRegOpers.Defs);
712 increaseVirtRegPressure(VirtRegOpers.Defs);
714 // Boost pressure for all dead defs together.
715 increasePhysRegPressure(PhysRegOpers.DeadDefs);
716 increaseVirtRegPressure(VirtRegOpers.DeadDefs);
717 decreasePhysRegPressure(PhysRegOpers.DeadDefs);
718 decreaseVirtRegPressure(VirtRegOpers.DeadDefs);
721 computeMaxPressureDelta(SavedPressure, CurrSetPressure,
722 Delta.ExcessSetID, TRI);
723 Delta.MaxUnitIncrease =
724 computeMaxPressureDelta(SavedMaxPressure, P.MaxSetPressure,
725 Delta.MaxSetID, TRI);
727 // Restore the tracker's state.
728 P.MaxSetPressure.swap(SavedMaxPressure);
729 CurrSetPressure.swap(SavedPressure);