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Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +00001//===---------- SplitKit.cpp - Toolkit for splitting live ranges ----------===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file contains the SplitAnalysis class as well as mutator functions for
11// live range splitting.
12//
13//===----------------------------------------------------------------------===//
14
15#define DEBUG_TYPE "splitter"
16#include "SplitKit.h"
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +000017#include "VirtRegMap.h"
Jakob Stoklund Olesen08e93b12010-08-10 17:07:22 +000018#include "llvm/CodeGen/CalcSpillWeights.h"
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +000019#include "llvm/CodeGen/LiveIntervalAnalysis.h"
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +000020#include "llvm/CodeGen/MachineInstrBuilder.h"
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +000021#include "llvm/CodeGen/MachineLoopInfo.h"
22#include "llvm/CodeGen/MachineRegisterInfo.h"
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +000023#include "llvm/Support/CommandLine.h"
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +000024#include "llvm/Support/Debug.h"
25#include "llvm/Support/raw_ostream.h"
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +000026#include "llvm/Target/TargetInstrInfo.h"
27#include "llvm/Target/TargetMachine.h"
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +000028
29using namespace llvm;
30
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +000031static cl::opt<bool>
32AllowSplit("spiller-splits-edges",
33 cl::desc("Allow critical edge splitting during spilling"));
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +000034
35//===----------------------------------------------------------------------===//
36// Split Analysis
37//===----------------------------------------------------------------------===//
38
Jakob Stoklund Olesenf2c6e362010-07-20 23:50:15 +000039SplitAnalysis::SplitAnalysis(const MachineFunction &mf,
40 const LiveIntervals &lis,
41 const MachineLoopInfo &mli)
42 : mf_(mf),
43 lis_(lis),
44 loops_(mli),
45 tii_(*mf.getTarget().getInstrInfo()),
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +000046 curli_(0) {}
47
48void SplitAnalysis::clear() {
49 usingInstrs_.clear();
50 usingBlocks_.clear();
51 usingLoops_.clear();
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +000052 curli_ = 0;
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +000053}
54
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +000055bool SplitAnalysis::canAnalyzeBranch(const MachineBasicBlock *MBB) {
56 MachineBasicBlock *T, *F;
57 SmallVector<MachineOperand, 4> Cond;
58 return !tii_.AnalyzeBranch(const_cast<MachineBasicBlock&>(*MBB), T, F, Cond);
59}
60
Jakob Stoklund Olesenabff2802010-07-20 16:12:37 +000061/// analyzeUses - Count instructions, basic blocks, and loops using curli.
62void SplitAnalysis::analyzeUses() {
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +000063 const MachineRegisterInfo &MRI = mf_.getRegInfo();
64 for (MachineRegisterInfo::reg_iterator I = MRI.reg_begin(curli_->reg);
65 MachineInstr *MI = I.skipInstruction();) {
66 if (MI->isDebugValue() || !usingInstrs_.insert(MI))
67 continue;
68 MachineBasicBlock *MBB = MI->getParent();
69 if (usingBlocks_[MBB]++)
70 continue;
71 if (MachineLoop *Loop = loops_.getLoopFor(MBB))
Jakob Stoklund Olesen2dee7a52010-08-12 23:02:55 +000072 usingLoops_[Loop]++;
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +000073 }
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +000074 DEBUG(dbgs() << " counted "
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +000075 << usingInstrs_.size() << " instrs, "
76 << usingBlocks_.size() << " blocks, "
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +000077 << usingLoops_.size() << " loops.\n");
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +000078}
79
Jakob Stoklund Olesen2dee7a52010-08-12 23:02:55 +000080/// removeUse - Update statistics by noting that MI no longer uses curli.
81void SplitAnalysis::removeUse(const MachineInstr *MI) {
82 if (!usingInstrs_.erase(MI))
83 return;
84
85 // Decrement MBB count.
86 const MachineBasicBlock *MBB = MI->getParent();
87 BlockCountMap::iterator bi = usingBlocks_.find(MBB);
88 assert(bi != usingBlocks_.end() && "MBB missing");
89 assert(bi->second && "0 count in map");
90 if (--bi->second)
91 return;
92 // No more uses in MBB.
93 usingBlocks_.erase(bi);
94
95 // Decrement loop count.
96 MachineLoop *Loop = loops_.getLoopFor(MBB);
97 if (!Loop)
98 return;
99 LoopCountMap::iterator li = usingLoops_.find(Loop);
100 assert(li != usingLoops_.end() && "Loop missing");
101 assert(li->second && "0 count in map");
102 if (--li->second)
103 return;
104 // No more blocks in Loop.
105 usingLoops_.erase(li);
106}
107
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +0000108// Get three sets of basic blocks surrounding a loop: Blocks inside the loop,
109// predecessor blocks, and exit blocks.
110void SplitAnalysis::getLoopBlocks(const MachineLoop *Loop, LoopBlocks &Blocks) {
111 Blocks.clear();
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +0000112
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +0000113 // Blocks in the loop.
114 Blocks.Loop.insert(Loop->block_begin(), Loop->block_end());
115
116 // Predecessor blocks.
117 const MachineBasicBlock *Header = Loop->getHeader();
118 for (MachineBasicBlock::const_pred_iterator I = Header->pred_begin(),
119 E = Header->pred_end(); I != E; ++I)
120 if (!Blocks.Loop.count(*I))
121 Blocks.Preds.insert(*I);
122
123 // Exit blocks.
124 for (MachineLoop::block_iterator I = Loop->block_begin(),
125 E = Loop->block_end(); I != E; ++I) {
126 const MachineBasicBlock *MBB = *I;
127 for (MachineBasicBlock::const_succ_iterator SI = MBB->succ_begin(),
128 SE = MBB->succ_end(); SI != SE; ++SI)
129 if (!Blocks.Loop.count(*SI))
130 Blocks.Exits.insert(*SI);
131 }
132}
133
134/// analyzeLoopPeripheralUse - Return an enum describing how curli_ is used in
135/// and around the Loop.
136SplitAnalysis::LoopPeripheralUse SplitAnalysis::
137analyzeLoopPeripheralUse(const SplitAnalysis::LoopBlocks &Blocks) {
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +0000138 LoopPeripheralUse use = ContainedInLoop;
139 for (BlockCountMap::iterator I = usingBlocks_.begin(), E = usingBlocks_.end();
140 I != E; ++I) {
141 const MachineBasicBlock *MBB = I->first;
142 // Is this a peripheral block?
143 if (use < MultiPeripheral &&
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +0000144 (Blocks.Preds.count(MBB) || Blocks.Exits.count(MBB))) {
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +0000145 if (I->second > 1) use = MultiPeripheral;
146 else use = SinglePeripheral;
147 continue;
148 }
149 // Is it a loop block?
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +0000150 if (Blocks.Loop.count(MBB))
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +0000151 continue;
152 // It must be an unrelated block.
153 return OutsideLoop;
154 }
155 return use;
156}
157
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +0000158/// getCriticalExits - It may be necessary to partially break critical edges
159/// leaving the loop if an exit block has phi uses of curli. Collect the exit
160/// blocks that need special treatment into CriticalExits.
161void SplitAnalysis::getCriticalExits(const SplitAnalysis::LoopBlocks &Blocks,
162 BlockPtrSet &CriticalExits) {
163 CriticalExits.clear();
164
165 // A critical exit block contains a phi def of curli, and has a predecessor
166 // that is not in the loop nor a loop predecessor.
167 // For such an exit block, the edges carrying the new variable must be moved
168 // to a new pre-exit block.
169 for (BlockPtrSet::iterator I = Blocks.Exits.begin(), E = Blocks.Exits.end();
170 I != E; ++I) {
171 const MachineBasicBlock *Succ = *I;
172 SlotIndex SuccIdx = lis_.getMBBStartIdx(Succ);
173 VNInfo *SuccVNI = curli_->getVNInfoAt(SuccIdx);
174 // This exit may not have curli live in at all. No need to split.
175 if (!SuccVNI)
176 continue;
177 // If this is not a PHI def, it is either using a value from before the
178 // loop, or a value defined inside the loop. Both are safe.
179 if (!SuccVNI->isPHIDef() || SuccVNI->def.getBaseIndex() != SuccIdx)
180 continue;
181 // This exit block does have a PHI. Does it also have a predecessor that is
182 // not a loop block or loop predecessor?
183 for (MachineBasicBlock::const_pred_iterator PI = Succ->pred_begin(),
184 PE = Succ->pred_end(); PI != PE; ++PI) {
185 const MachineBasicBlock *Pred = *PI;
186 if (Blocks.Loop.count(Pred) || Blocks.Preds.count(Pred))
187 continue;
188 // This is a critical exit block, and we need to split the exit edge.
189 CriticalExits.insert(Succ);
190 break;
191 }
192 }
193}
194
195/// canSplitCriticalExits - Return true if it is possible to insert new exit
196/// blocks before the blocks in CriticalExits.
197bool
198SplitAnalysis::canSplitCriticalExits(const SplitAnalysis::LoopBlocks &Blocks,
199 BlockPtrSet &CriticalExits) {
200 // If we don't allow critical edge splitting, require no critical exits.
201 if (!AllowSplit)
202 return CriticalExits.empty();
203
204 for (BlockPtrSet::iterator I = CriticalExits.begin(), E = CriticalExits.end();
205 I != E; ++I) {
206 const MachineBasicBlock *Succ = *I;
207 // We want to insert a new pre-exit MBB before Succ, and change all the
208 // in-loop blocks to branch to the pre-exit instead of Succ.
209 // Check that all the in-loop predecessors can be changed.
210 for (MachineBasicBlock::const_pred_iterator PI = Succ->pred_begin(),
211 PE = Succ->pred_end(); PI != PE; ++PI) {
212 const MachineBasicBlock *Pred = *PI;
213 // The external predecessors won't be altered.
214 if (!Blocks.Loop.count(Pred) && !Blocks.Preds.count(Pred))
215 continue;
216 if (!canAnalyzeBranch(Pred))
217 return false;
218 }
219
220 // If Succ's layout predecessor falls through, that too must be analyzable.
221 // We need to insert the pre-exit block in the gap.
222 MachineFunction::const_iterator MFI = Succ;
223 if (MFI == mf_.begin())
224 continue;
225 if (!canAnalyzeBranch(--MFI))
226 return false;
227 }
228 // No problems found.
229 return true;
230}
231
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +0000232void SplitAnalysis::analyze(const LiveInterval *li) {
233 clear();
234 curli_ = li;
Jakob Stoklund Olesenabff2802010-07-20 16:12:37 +0000235 analyzeUses();
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +0000236}
237
238const MachineLoop *SplitAnalysis::getBestSplitLoop() {
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +0000239 assert(curli_ && "Call analyze() before getBestSplitLoop");
240 if (usingLoops_.empty())
241 return 0;
242
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +0000243 LoopPtrSet Loops, SecondLoops;
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +0000244 LoopBlocks Blocks;
245 BlockPtrSet CriticalExits;
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +0000246
247 // Find first-class and second class candidate loops.
248 // We prefer to split around loops where curli is used outside the periphery.
Jakob Stoklund Olesen2dee7a52010-08-12 23:02:55 +0000249 for (LoopCountMap::const_iterator I = usingLoops_.begin(),
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +0000250 E = usingLoops_.end(); I != E; ++I) {
Jakob Stoklund Olesen2dee7a52010-08-12 23:02:55 +0000251 const MachineLoop *Loop = I->first;
252 getLoopBlocks(Loop, Blocks);
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000253
254 // FIXME: We need an SSA updater to properly handle multiple exit blocks.
255 if (Blocks.Exits.size() > 1) {
Jakob Stoklund Olesen2dee7a52010-08-12 23:02:55 +0000256 DEBUG(dbgs() << " multiple exits from " << *Loop);
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000257 continue;
258 }
259
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +0000260 LoopPtrSet *LPS = 0;
261 switch(analyzeLoopPeripheralUse(Blocks)) {
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +0000262 case OutsideLoop:
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +0000263 LPS = &Loops;
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +0000264 break;
265 case MultiPeripheral:
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +0000266 LPS = &SecondLoops;
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +0000267 break;
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +0000268 case ContainedInLoop:
Jakob Stoklund Olesen2dee7a52010-08-12 23:02:55 +0000269 DEBUG(dbgs() << " contained in " << *Loop);
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +0000270 continue;
271 case SinglePeripheral:
Jakob Stoklund Olesen2dee7a52010-08-12 23:02:55 +0000272 DEBUG(dbgs() << " single peripheral use in " << *Loop);
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +0000273 continue;
274 }
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +0000275 // Will it be possible to split around this loop?
276 getCriticalExits(Blocks, CriticalExits);
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000277 DEBUG(dbgs() << " " << CriticalExits.size() << " critical exits from "
Jakob Stoklund Olesen2dee7a52010-08-12 23:02:55 +0000278 << *Loop);
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +0000279 if (!canSplitCriticalExits(Blocks, CriticalExits))
280 continue;
281 // This is a possible split.
282 assert(LPS);
Jakob Stoklund Olesen2dee7a52010-08-12 23:02:55 +0000283 LPS->insert(Loop);
Jakob Stoklund Olesen6a0dc072010-07-20 21:46:58 +0000284 }
285
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000286 DEBUG(dbgs() << " getBestSplitLoop found " << Loops.size() << " + "
287 << SecondLoops.size() << " candidate loops.\n");
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +0000288
289 // If there are no first class loops available, look at second class loops.
290 if (Loops.empty())
291 Loops = SecondLoops;
292
293 if (Loops.empty())
294 return 0;
295
296 // Pick the earliest loop.
297 // FIXME: Are there other heuristics to consider?
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +0000298 const MachineLoop *Best = 0;
299 SlotIndex BestIdx;
300 for (LoopPtrSet::const_iterator I = Loops.begin(), E = Loops.end(); I != E;
301 ++I) {
302 SlotIndex Idx = lis_.getMBBStartIdx((*I)->getHeader());
303 if (!Best || Idx < BestIdx)
304 Best = *I, BestIdx = Idx;
305 }
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000306 DEBUG(dbgs() << " getBestSplitLoop found " << *Best);
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +0000307 return Best;
308}
309
Jakob Stoklund Olesenf1b05f22010-08-12 17:07:14 +0000310/// getMultiUseBlocks - if curli has more than one use in a basic block, it
311/// may be an advantage to split curli for the duration of the block.
312bool SplitAnalysis::getMultiUseBlocks(BlockPtrSet &Blocks) {
313 // If curli is local to one block, there is no point to splitting it.
314 if (usingBlocks_.size() <= 1)
315 return false;
316 // Add blocks with multiple uses.
317 for (BlockCountMap::iterator I = usingBlocks_.begin(), E = usingBlocks_.end();
318 I != E; ++I)
319 switch (I->second) {
320 case 0:
321 case 1:
322 continue;
323 case 2: {
324 // It doesn't pay to split a 2-instr block if it redefines curli.
325 VNInfo *VN1 = curli_->getVNInfoAt(lis_.getMBBStartIdx(I->first));
326 VNInfo *VN2 =
327 curli_->getVNInfoAt(lis_.getMBBEndIdx(I->first).getPrevIndex());
328 // live-in and live-out with a different value.
329 if (VN1 && VN2 && VN1 != VN2)
330 continue;
331 } // Fall through.
332 default:
333 Blocks.insert(I->first);
334 }
335 return !Blocks.empty();
336}
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000337
338//===----------------------------------------------------------------------===//
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000339// LiveIntervalMap
340//===----------------------------------------------------------------------===//
341
Jakob Stoklund Olesenb3e96812010-09-13 21:29:45 +0000342// Work around the fact that the std::pair constructors are broken for pointer
343// pairs in some implementations. makeVV(x, 0) works.
344static inline std::pair<const VNInfo*, VNInfo*>
345makeVV(const VNInfo *a, VNInfo *b) {
346 return std::make_pair(a, b);
347}
348
Jakob Stoklund Olesen9ca2aeb2010-09-13 23:29:09 +0000349void LiveIntervalMap::reset(LiveInterval *li) {
350 li_ = li;
351 valueMap_.clear();
352}
353
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000354// defValue - Introduce a li_ def for ParentVNI that could be later than
355// ParentVNI->def.
356VNInfo *LiveIntervalMap::defValue(const VNInfo *ParentVNI, SlotIndex Idx) {
Jakob Stoklund Olesen9ca2aeb2010-09-13 23:29:09 +0000357 assert(li_ && "call reset first");
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000358 assert(ParentVNI && "Mapping NULL value");
359 assert(Idx.isValid() && "Invalid SlotIndex");
360 assert(parentli_.getVNInfoAt(Idx) == ParentVNI && "Bad ParentVNI");
361
362 // Is this a simple 1-1 mapping? Not likely.
363 if (Idx == ParentVNI->def)
364 return mapValue(ParentVNI, Idx);
365
366 // This is a complex def. Mark with a NULL in valueMap.
Jakob Stoklund Olesenb3e96812010-09-13 21:29:45 +0000367 VNInfo *&OldVNI = valueMap_[ParentVNI];
368 assert(!OldVNI && "Simple/Complex values mixed");
369 OldVNI = 0;
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000370
371 // Should we insert a minimal snippet of VNI LiveRange, or can we count on
372 // callers to do that? We need it for lookups of complex values.
Jakob Stoklund Olesen9ca2aeb2010-09-13 23:29:09 +0000373 VNInfo *VNI = li_->getNextValue(Idx, 0, true, lis_.getVNInfoAllocator());
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000374 return VNI;
375}
376
377// mapValue - Find the mapped value for ParentVNI at Idx.
378// Potentially create phi-def values.
379VNInfo *LiveIntervalMap::mapValue(const VNInfo *ParentVNI, SlotIndex Idx) {
Jakob Stoklund Olesen9ca2aeb2010-09-13 23:29:09 +0000380 assert(li_ && "call reset first");
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000381 assert(ParentVNI && "Mapping NULL value");
382 assert(Idx.isValid() && "Invalid SlotIndex");
383 assert(parentli_.getVNInfoAt(Idx) == ParentVNI && "Bad ParentVNI");
384
385 // Use insert for lookup, so we can add missing values with a second lookup.
386 std::pair<ValueMap::iterator,bool> InsP =
Jakob Stoklund Olesenb3e96812010-09-13 21:29:45 +0000387 valueMap_.insert(makeVV(ParentVNI, 0));
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000388
389 // This was an unknown value. Create a simple mapping.
390 if (InsP.second)
Jakob Stoklund Olesen9ca2aeb2010-09-13 23:29:09 +0000391 return InsP.first->second = li_->createValueCopy(ParentVNI,
392 lis_.getVNInfoAllocator());
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000393 // This was a simple mapped value.
394 if (InsP.first->second)
395 return InsP.first->second;
396
397 // This is a complex mapped value. There may be multiple defs, and we may need
398 // to create phi-defs.
399 MachineBasicBlock *IdxMBB = lis_.getMBBFromIndex(Idx);
400 assert(IdxMBB && "No MBB at Idx");
401
402 // Is there a def in the same MBB we can extend?
403 if (VNInfo *VNI = extendTo(IdxMBB, Idx))
404 return VNI;
405
406 // Now for the fun part. We know that ParentVNI potentially has multiple defs,
407 // and we may need to create even more phi-defs to preserve VNInfo SSA form.
408 // Perform a depth-first search for predecessor blocks where we know the
409 // dominating VNInfo. Insert phi-def VNInfos along the path back to IdxMBB.
410
411 // Track MBBs where we have created or learned the dominating value.
412 // This may change during the DFS as we create new phi-defs.
413 typedef DenseMap<MachineBasicBlock*, VNInfo*> MBBValueMap;
414 MBBValueMap DomValue;
415
416 for (idf_iterator<MachineBasicBlock*>
417 IDFI = idf_begin(IdxMBB),
418 IDFE = idf_end(IdxMBB); IDFI != IDFE;) {
419 MachineBasicBlock *MBB = *IDFI;
420 SlotIndex End = lis_.getMBBEndIdx(MBB);
421
422 // We are operating on the restricted CFG where ParentVNI is live.
423 if (parentli_.getVNInfoAt(End.getPrevSlot()) != ParentVNI) {
424 IDFI.skipChildren();
425 continue;
426 }
427
428 // Do we have a dominating value in this block?
429 VNInfo *VNI = extendTo(MBB, End);
430 if (!VNI) {
431 ++IDFI;
432 continue;
433 }
434
435 // Yes, VNI dominates MBB. Track the path back to IdxMBB, creating phi-defs
436 // as needed along the way.
437 for (unsigned PI = IDFI.getPathLength()-1; PI != 0; --PI) {
Jakob Stoklund Olesenff3ae862010-08-18 20:29:53 +0000438 // Start from MBB's immediate successor. End at IdxMBB.
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000439 MachineBasicBlock *Succ = IDFI.getPath(PI-1);
440 std::pair<MBBValueMap::iterator, bool> InsP =
441 DomValue.insert(MBBValueMap::value_type(Succ, VNI));
Jakob Stoklund Olesenff3ae862010-08-18 20:29:53 +0000442
443 // This is the first time we backtrack to Succ.
444 if (InsP.second)
445 continue;
446
447 // We reached Succ again with the same VNI. Nothing is going to change.
448 VNInfo *OVNI = InsP.first->second;
449 if (OVNI == VNI)
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000450 break;
Jakob Stoklund Olesenff3ae862010-08-18 20:29:53 +0000451
452 // Succ already has a phi-def. No need to continue.
453 SlotIndex Start = lis_.getMBBStartIdx(Succ);
454 if (OVNI->def == Start)
455 break;
456
457 // We have a collision between the old and new VNI at Succ. That means
458 // neither dominates and we need a new phi-def.
Jakob Stoklund Olesen9ca2aeb2010-09-13 23:29:09 +0000459 VNI = li_->getNextValue(Start, 0, true, lis_.getVNInfoAllocator());
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000460 VNI->setIsPHIDef(true);
461 InsP.first->second = VNI;
Jakob Stoklund Olesenff3ae862010-08-18 20:29:53 +0000462
463 // Replace OVNI with VNI in the remaining path.
464 for (; PI > 1 ; --PI) {
465 MBBValueMap::iterator I = DomValue.find(IDFI.getPath(PI-2));
466 if (I == DomValue.end() || I->second != OVNI)
467 break;
468 I->second = VNI;
469 }
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000470 }
471
472 // No need to search the children, we found a dominating value.
Jakob Stoklund Olesencf16bea2010-08-18 20:06:05 +0000473 IDFI.skipChildren();
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000474 }
475
476 // The search should at least find a dominating value for IdxMBB.
477 assert(!DomValue.empty() && "Couldn't find a reaching definition");
478
479 // Since we went through the trouble of a full DFS visiting all reaching defs,
480 // the values in DomValue are now accurate. No more phi-defs are needed for
481 // these blocks, so we can color the live ranges.
482 // This makes the next mapValue call much faster.
483 VNInfo *IdxVNI = 0;
484 for (MBBValueMap::iterator I = DomValue.begin(), E = DomValue.end(); I != E;
485 ++I) {
486 MachineBasicBlock *MBB = I->first;
487 VNInfo *VNI = I->second;
488 SlotIndex Start = lis_.getMBBStartIdx(MBB);
489 if (MBB == IdxMBB) {
490 // Don't add full liveness to IdxMBB, stop at Idx.
491 if (Start != Idx)
Jakob Stoklund Olesen9ca2aeb2010-09-13 23:29:09 +0000492 li_->addRange(LiveRange(Start, Idx, VNI));
Jakob Stoklund Olesenff3ae862010-08-18 20:29:53 +0000493 // The caller had better add some liveness to IdxVNI, or it leaks.
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000494 IdxVNI = VNI;
495 } else
Jakob Stoklund Olesen9ca2aeb2010-09-13 23:29:09 +0000496 li_->addRange(LiveRange(Start, lis_.getMBBEndIdx(MBB), VNI));
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000497 }
498
499 assert(IdxVNI && "Didn't find value for Idx");
500 return IdxVNI;
501}
502
503// extendTo - Find the last li_ value defined in MBB at or before Idx. The
504// parentli_ is assumed to be live at Idx. Extend the live range to Idx.
505// Return the found VNInfo, or NULL.
506VNInfo *LiveIntervalMap::extendTo(MachineBasicBlock *MBB, SlotIndex Idx) {
Jakob Stoklund Olesen9ca2aeb2010-09-13 23:29:09 +0000507 assert(li_ && "call reset first");
508 LiveInterval::iterator I = std::upper_bound(li_->begin(), li_->end(), Idx);
509 if (I == li_->begin())
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000510 return 0;
511 --I;
512 if (I->start < lis_.getMBBStartIdx(MBB))
513 return 0;
514 if (I->end < Idx)
515 I->end = Idx;
516 return I->valno;
517}
518
519// addSimpleRange - Add a simple range from parentli_ to li_.
520// ParentVNI must be live in the [Start;End) interval.
521void LiveIntervalMap::addSimpleRange(SlotIndex Start, SlotIndex End,
522 const VNInfo *ParentVNI) {
Jakob Stoklund Olesen9ca2aeb2010-09-13 23:29:09 +0000523 assert(li_ && "call reset first");
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000524 VNInfo *VNI = mapValue(ParentVNI, Start);
525 // A simple mappoing is easy.
526 if (VNI->def == ParentVNI->def) {
Jakob Stoklund Olesen9ca2aeb2010-09-13 23:29:09 +0000527 li_->addRange(LiveRange(Start, End, VNI));
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000528 return;
529 }
530
531 // ParentVNI is a complex value. We must map per MBB.
532 MachineFunction::iterator MBB = lis_.getMBBFromIndex(Start);
533 MachineFunction::iterator MBBE = lis_.getMBBFromIndex(End);
534
535 if (MBB == MBBE) {
Jakob Stoklund Olesen9ca2aeb2010-09-13 23:29:09 +0000536 li_->addRange(LiveRange(Start, End, VNI));
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000537 return;
538 }
539
540 // First block.
Jakob Stoklund Olesen9ca2aeb2010-09-13 23:29:09 +0000541 li_->addRange(LiveRange(Start, lis_.getMBBEndIdx(MBB), VNI));
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000542
543 // Run sequence of full blocks.
544 for (++MBB; MBB != MBBE; ++MBB) {
545 Start = lis_.getMBBStartIdx(MBB);
Jakob Stoklund Olesen9ca2aeb2010-09-13 23:29:09 +0000546 li_->addRange(LiveRange(Start, lis_.getMBBEndIdx(MBB),
547 mapValue(ParentVNI, Start)));
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000548 }
549
550 // Final block.
551 Start = lis_.getMBBStartIdx(MBB);
552 if (Start != End)
Jakob Stoklund Olesen9ca2aeb2010-09-13 23:29:09 +0000553 li_->addRange(LiveRange(Start, End, mapValue(ParentVNI, Start)));
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000554}
555
556/// addRange - Add live ranges to li_ where [Start;End) intersects parentli_.
557/// All needed values whose def is not inside [Start;End) must be defined
558/// beforehand so mapValue will work.
559void LiveIntervalMap::addRange(SlotIndex Start, SlotIndex End) {
Jakob Stoklund Olesen9ca2aeb2010-09-13 23:29:09 +0000560 assert(li_ && "call reset first");
Jakob Stoklund Olesen1407c842010-08-18 19:00:08 +0000561 LiveInterval::const_iterator B = parentli_.begin(), E = parentli_.end();
562 LiveInterval::const_iterator I = std::lower_bound(B, E, Start);
563
564 // Check if --I begins before Start and overlaps.
565 if (I != B) {
566 --I;
567 if (I->end > Start)
568 addSimpleRange(Start, std::min(End, I->end), I->valno);
569 ++I;
570 }
571
572 // The remaining ranges begin after Start.
573 for (;I != E && I->start < End; ++I)
574 addSimpleRange(I->start, std::min(End, I->end), I->valno);
575}
576
577//===----------------------------------------------------------------------===//
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000578// Split Editor
579//===----------------------------------------------------------------------===//
580
581/// Create a new SplitEditor for editing the LiveInterval analyzed by SA.
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000582SplitEditor::SplitEditor(SplitAnalysis &sa, LiveIntervals &lis, VirtRegMap &vrm,
Jakob Stoklund Olesen0a2b2a12010-08-13 22:56:53 +0000583 SmallVectorImpl<LiveInterval*> &intervals)
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000584 : sa_(sa), lis_(lis), vrm_(vrm),
585 mri_(vrm.getMachineFunction().getRegInfo()),
586 tii_(*vrm.getMachineFunction().getTarget().getInstrInfo()),
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000587 curli_(sa_.getCurLI()),
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000588 dupli_(0), openli_(0),
589 intervals_(intervals),
590 firstInterval(intervals_.size())
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000591{
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000592 assert(curli_ && "SplitEditor created from empty SplitAnalysis");
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000593
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000594 // Make sure curli_ is assigned a stack slot, so all our intervals get the
595 // same slot as curli_.
596 if (vrm_.getStackSlot(curli_->reg) == VirtRegMap::NO_STACK_SLOT)
597 vrm_.assignVirt2StackSlot(curli_->reg);
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000598
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000599}
600
601LiveInterval *SplitEditor::createInterval() {
602 unsigned curli = sa_.getCurLI()->reg;
603 unsigned Reg = mri_.createVirtualRegister(mri_.getRegClass(curli));
604 LiveInterval &Intv = lis_.getOrCreateInterval(Reg);
605 vrm_.grow();
606 vrm_.assignVirt2StackSlot(Reg, vrm_.getStackSlot(curli));
607 return &Intv;
608}
609
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000610LiveInterval *SplitEditor::getDupLI() {
611 if (!dupli_) {
612 // Create an interval for dupli that is a copy of curli.
613 dupli_ = createInterval();
614 dupli_->Copy(*curli_, &mri_, lis_.getVNInfoAllocator());
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000615 }
616 return dupli_;
617}
618
619VNInfo *SplitEditor::mapValue(const VNInfo *curliVNI) {
620 VNInfo *&VNI = valueMap_[curliVNI];
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000621 if (!VNI)
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000622 VNI = openli_->createValueCopy(curliVNI, lis_.getVNInfoAllocator());
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000623 return VNI;
624}
625
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000626/// Insert a COPY instruction curli -> li. Allocate a new value from li
627/// defined by the COPY. Note that rewrite() will deal with the curli
628/// register, so this function can be used to copy from any interval - openli,
629/// curli, or dupli.
630VNInfo *SplitEditor::insertCopy(LiveInterval &LI,
631 MachineBasicBlock &MBB,
632 MachineBasicBlock::iterator I) {
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000633 MachineInstr *MI = BuildMI(MBB, I, DebugLoc(), tii_.get(TargetOpcode::COPY),
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000634 LI.reg).addReg(curli_->reg);
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000635 SlotIndex DefIdx = lis_.InsertMachineInstrInMaps(MI).getDefIndex();
636 return LI.getNextValue(DefIdx, MI, true, lis_.getVNInfoAllocator());
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000637}
638
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000639/// Create a new virtual register and live interval.
640void SplitEditor::openIntv() {
641 assert(!openli_ && "Previous LI not closed before openIntv");
642 openli_ = createInterval();
643 intervals_.push_back(openli_);
644 liveThrough_ = false;
645}
646
Jakob Stoklund Olesenf1b05f22010-08-12 17:07:14 +0000647/// enterIntvBefore - Enter openli before the instruction at Idx. If curli is
648/// not live before Idx, a COPY is not inserted.
649void SplitEditor::enterIntvBefore(SlotIndex Idx) {
650 assert(openli_ && "openIntv not called before enterIntvBefore");
651
652 // Copy from curli_ if it is live.
653 if (VNInfo *CurVNI = curli_->getVNInfoAt(Idx.getUseIndex())) {
654 MachineInstr *MI = lis_.getInstructionFromIndex(Idx);
655 assert(MI && "enterIntvBefore called with invalid index");
656 VNInfo *VNI = insertCopy(*openli_, *MI->getParent(), MI);
657 openli_->addRange(LiveRange(VNI->def, Idx.getDefIndex(), VNI));
658
659 // Make sure CurVNI is properly mapped.
660 VNInfo *&mapVNI = valueMap_[CurVNI];
661 // We dont have SSA update yet, so only one entry per value is allowed.
662 assert(!mapVNI && "enterIntvBefore called more than once for the same value");
663 mapVNI = VNI;
664 }
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000665 DEBUG(dbgs() << " enterIntvBefore " << Idx << ": " << *openli_ << '\n');
Jakob Stoklund Olesenf1b05f22010-08-12 17:07:14 +0000666}
667
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000668/// enterIntvAtEnd - Enter openli at the end of MBB.
669/// PhiMBB is a successor inside openli where a PHI value is created.
670/// Currently, all entries must share the same PhiMBB.
671void SplitEditor::enterIntvAtEnd(MachineBasicBlock &A, MachineBasicBlock &B) {
672 assert(openli_ && "openIntv not called before enterIntvAtEnd");
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000673
674 SlotIndex EndA = lis_.getMBBEndIdx(&A);
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000675 VNInfo *CurVNIA = curli_->getVNInfoAt(EndA.getPrevIndex());
676 if (!CurVNIA) {
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000677 DEBUG(dbgs() << " enterIntvAtEnd, curli not live out of BB#"
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000678 << A.getNumber() << ".\n");
679 return;
680 }
681
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000682 // Add a phi kill value and live range out of A.
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000683 VNInfo *VNIA = insertCopy(*openli_, A, A.getFirstTerminator());
684 openli_->addRange(LiveRange(VNIA->def, EndA, VNIA));
685
686 // FIXME: If this is the only entry edge, we don't need the extra PHI value.
687 // FIXME: If there are multiple entry blocks (so not a loop), we need proper
688 // SSA update.
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000689
690 // Now look at the start of B.
691 SlotIndex StartB = lis_.getMBBStartIdx(&B);
692 SlotIndex EndB = lis_.getMBBEndIdx(&B);
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000693 const LiveRange *CurB = curli_->getLiveRangeContaining(StartB);
694 if (!CurB) {
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000695 DEBUG(dbgs() << " enterIntvAtEnd: curli not live in to BB#"
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000696 << B.getNumber() << ".\n");
697 return;
698 }
699
700 VNInfo *VNIB = openli_->getVNInfoAt(StartB);
701 if (!VNIB) {
702 // Create a phi value.
703 VNIB = openli_->getNextValue(SlotIndex(StartB, true), 0, false,
704 lis_.getVNInfoAllocator());
705 VNIB->setIsPHIDef(true);
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000706 VNInfo *&mapVNI = valueMap_[CurB->valno];
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000707 if (mapVNI) {
708 // Multiple copies - must create PHI value.
709 abort();
710 } else {
711 // This is the first copy of dupLR. Mark the mapping.
712 mapVNI = VNIB;
713 }
714
715 }
716
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000717 DEBUG(dbgs() << " enterIntvAtEnd: " << *openli_ << '\n');
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000718}
719
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000720/// useIntv - indicate that all instructions in MBB should use openli.
721void SplitEditor::useIntv(const MachineBasicBlock &MBB) {
722 useIntv(lis_.getMBBStartIdx(&MBB), lis_.getMBBEndIdx(&MBB));
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000723}
724
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000725void SplitEditor::useIntv(SlotIndex Start, SlotIndex End) {
726 assert(openli_ && "openIntv not called before useIntv");
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000727
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000728 // Map the curli values from the interval into openli_
729 LiveInterval::const_iterator B = curli_->begin(), E = curli_->end();
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000730 LiveInterval::const_iterator I = std::lower_bound(B, E, Start);
731
732 if (I != B) {
733 --I;
Jakob Stoklund Olesen2780d3c2010-08-13 01:05:26 +0000734 // I begins before Start, but overlaps.
735 if (I->end > Start)
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000736 openli_->addRange(LiveRange(Start, std::min(End, I->end),
737 mapValue(I->valno)));
738 ++I;
739 }
740
741 // The remaining ranges begin after Start.
742 for (;I != E && I->start < End; ++I)
743 openli_->addRange(LiveRange(I->start, std::min(End, I->end),
744 mapValue(I->valno)));
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000745 DEBUG(dbgs() << " use [" << Start << ';' << End << "): " << *openli_
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000746 << '\n');
747}
748
Jakob Stoklund Olesenf1b05f22010-08-12 17:07:14 +0000749/// leaveIntvAfter - Leave openli after the instruction at Idx.
750void SplitEditor::leaveIntvAfter(SlotIndex Idx) {
751 assert(openli_ && "openIntv not called before leaveIntvAfter");
752
753 const LiveRange *CurLR = curli_->getLiveRangeContaining(Idx.getDefIndex());
754 if (!CurLR || CurLR->end <= Idx.getBoundaryIndex()) {
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000755 DEBUG(dbgs() << " leaveIntvAfter " << Idx << ": not live\n");
Jakob Stoklund Olesenf1b05f22010-08-12 17:07:14 +0000756 return;
757 }
758
759 // Was this value of curli live through openli?
760 if (!openli_->liveAt(CurLR->valno->def)) {
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000761 DEBUG(dbgs() << " leaveIntvAfter " << Idx << ": using external value\n");
Jakob Stoklund Olesenf1b05f22010-08-12 17:07:14 +0000762 liveThrough_ = true;
763 return;
764 }
765
766 // We are going to insert a back copy, so we must have a dupli_.
767 LiveRange *DupLR = getDupLI()->getLiveRangeContaining(Idx.getDefIndex());
768 assert(DupLR && "dupli not live into black, but curli is?");
769
770 // Insert the COPY instruction.
771 MachineBasicBlock::iterator I = lis_.getInstructionFromIndex(Idx);
772 MachineInstr *MI = BuildMI(*I->getParent(), llvm::next(I), I->getDebugLoc(),
773 tii_.get(TargetOpcode::COPY), dupli_->reg)
774 .addReg(openli_->reg);
775 SlotIndex CopyIdx = lis_.InsertMachineInstrInMaps(MI).getDefIndex();
776 openli_->addRange(LiveRange(Idx.getDefIndex(), CopyIdx,
777 mapValue(CurLR->valno)));
778 DupLR->valno->def = CopyIdx;
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000779 DEBUG(dbgs() << " leaveIntvAfter " << Idx << ": " << *openli_ << '\n');
Jakob Stoklund Olesenf1b05f22010-08-12 17:07:14 +0000780}
781
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000782/// leaveIntvAtTop - Leave the interval at the top of MBB.
783/// Currently, only one value can leave the interval.
784void SplitEditor::leaveIntvAtTop(MachineBasicBlock &MBB) {
785 assert(openli_ && "openIntv not called before leaveIntvAtTop");
786
787 SlotIndex Start = lis_.getMBBStartIdx(&MBB);
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000788 const LiveRange *CurLR = curli_->getLiveRangeContaining(Start);
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000789
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000790 // Is curli even live-in to MBB?
791 if (!CurLR) {
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000792 DEBUG(dbgs() << " leaveIntvAtTop at " << Start << ": not live\n");
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000793 return;
794 }
795
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000796 // Is curli defined by PHI at the beginning of MBB?
797 bool isPHIDef = CurLR->valno->isPHIDef() &&
798 CurLR->valno->def.getBaseIndex() == Start;
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000799
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000800 // If MBB is using a value of curli that was defined outside the openli range,
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000801 // we don't want to copy it back here.
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000802 if (!isPHIDef && !openli_->liveAt(CurLR->valno->def)) {
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000803 DEBUG(dbgs() << " leaveIntvAtTop at " << Start
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000804 << ": using external value\n");
805 liveThrough_ = true;
806 return;
807 }
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000808
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000809 // We are going to insert a back copy, so we must have a dupli_.
810 LiveRange *DupLR = getDupLI()->getLiveRangeContaining(Start);
811 assert(DupLR && "dupli not live into black, but curli is?");
812
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000813 // Insert the COPY instruction.
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000814 MachineInstr *MI = BuildMI(MBB, MBB.begin(), DebugLoc(),
Jakob Stoklund Olesenb85f5382010-08-06 18:04:17 +0000815 tii_.get(TargetOpcode::COPY), dupli_->reg)
816 .addReg(openli_->reg);
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000817 SlotIndex Idx = lis_.InsertMachineInstrInMaps(MI).getDefIndex();
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000818
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000819 // Adjust dupli and openli values.
820 if (isPHIDef) {
821 // dupli was already a PHI on entry to MBB. Simply insert an openli PHI,
822 // and shift the dupli def down to the COPY.
823 VNInfo *VNI = openli_->getNextValue(SlotIndex(Start, true), 0, false,
824 lis_.getVNInfoAllocator());
825 VNI->setIsPHIDef(true);
826 openli_->addRange(LiveRange(VNI->def, Idx, VNI));
827
828 dupli_->removeRange(Start, Idx);
829 DupLR->valno->def = Idx;
830 DupLR->valno->setIsPHIDef(false);
831 } else {
832 // The dupli value was defined somewhere inside the openli range.
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000833 DEBUG(dbgs() << " leaveIntvAtTop source value defined at "
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000834 << DupLR->valno->def << "\n");
835 // FIXME: We may not need a PHI here if all predecessors have the same
836 // value.
837 VNInfo *VNI = openli_->getNextValue(SlotIndex(Start, true), 0, false,
838 lis_.getVNInfoAllocator());
839 VNI->setIsPHIDef(true);
840 openli_->addRange(LiveRange(VNI->def, Idx, VNI));
841
842 // FIXME: What if DupLR->valno is used by multiple exits? SSA Update.
843
844 // closeIntv is going to remove the superfluous live ranges.
845 DupLR->valno->def = Idx;
846 DupLR->valno->setIsPHIDef(false);
847 }
848
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000849 DEBUG(dbgs() << " leaveIntvAtTop at " << Idx << ": " << *openli_ << '\n');
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000850}
851
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000852/// closeIntv - Indicate that we are done editing the currently open
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000853/// LiveInterval, and ranges can be trimmed.
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000854void SplitEditor::closeIntv() {
855 assert(openli_ && "openIntv not called before closeIntv");
856
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000857 DEBUG(dbgs() << " closeIntv cleaning up\n");
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000858 DEBUG(dbgs() << " open " << *openli_ << '\n');
859
860 if (liveThrough_) {
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000861 DEBUG(dbgs() << " value live through region, leaving dupli as is.\n");
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000862 } else {
863 // live out with copies inserted, or killed by region. Either way we need to
864 // remove the overlapping region from dupli.
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000865 getDupLI();
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000866 for (LiveInterval::iterator I = openli_->begin(), E = openli_->end();
867 I != E; ++I) {
868 dupli_->removeRange(I->start, I->end);
869 }
870 // FIXME: A block branching to the entry block may also branch elsewhere
871 // curli is live. We need both openli and curli to be live in that case.
872 DEBUG(dbgs() << " dup2 " << *dupli_ << '\n');
873 }
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000874 openli_ = 0;
Jakob Stoklund Olesenf1b05f22010-08-12 17:07:14 +0000875 valueMap_.clear();
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000876}
877
878/// rewrite - after all the new live ranges have been created, rewrite
879/// instructions using curli to use the new intervals.
880void SplitEditor::rewrite() {
881 assert(!openli_ && "Previous LI not closed before rewrite");
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000882 const LiveInterval *curli = sa_.getCurLI();
883 for (MachineRegisterInfo::reg_iterator RI = mri_.reg_begin(curli->reg),
884 RE = mri_.reg_end(); RI != RE;) {
885 MachineOperand &MO = RI.getOperand();
886 MachineInstr *MI = MO.getParent();
887 ++RI;
888 if (MI->isDebugValue()) {
889 DEBUG(dbgs() << "Zapping " << *MI);
890 // FIXME: We can do much better with debug values.
891 MO.setReg(0);
892 continue;
893 }
894 SlotIndex Idx = lis_.getInstructionIndex(MI);
895 Idx = MO.isUse() ? Idx.getUseIndex() : Idx.getDefIndex();
896 LiveInterval *LI = dupli_;
897 for (unsigned i = firstInterval, e = intervals_.size(); i != e; ++i) {
898 LiveInterval *testli = intervals_[i];
899 if (testli->liveAt(Idx)) {
900 LI = testli;
901 break;
902 }
903 }
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000904 if (LI) {
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000905 MO.setReg(LI->reg);
Jakob Stoklund Olesen00667a52010-08-13 01:05:23 +0000906 sa_.removeUse(MI);
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000907 DEBUG(dbgs() << " rewrite " << Idx << '\t' << *MI);
908 }
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000909 }
910
911 // dupli_ goes in last, after rewriting.
Jakob Stoklund Olesen23436592010-08-06 18:46:59 +0000912 if (dupli_) {
Jakob Stoklund Olesen09c45d22010-08-12 23:02:57 +0000913 if (dupli_->empty()) {
914 DEBUG(dbgs() << " dupli became empty?\n");
915 lis_.removeInterval(dupli_->reg);
916 dupli_ = 0;
917 } else {
918 dupli_->RenumberValues(lis_);
919 intervals_.push_back(dupli_);
920 }
Jakob Stoklund Olesen23436592010-08-06 18:46:59 +0000921 }
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000922
Jakob Stoklund Olesen08e93b12010-08-10 17:07:22 +0000923 // Calculate spill weight and allocation hints for new intervals.
924 VirtRegAuxInfo vrai(vrm_.getMachineFunction(), lis_, sa_.loops_);
925 for (unsigned i = firstInterval, e = intervals_.size(); i != e; ++i) {
926 LiveInterval &li = *intervals_[i];
Jakob Stoklund Olesen9db3ea42010-08-10 18:37:40 +0000927 vrai.CalculateRegClass(li.reg);
Jakob Stoklund Olesen08e93b12010-08-10 17:07:22 +0000928 vrai.CalculateWeightAndHint(li);
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000929 DEBUG(dbgs() << " new interval " << mri_.getRegClass(li.reg)->getName()
930 << ":" << li << '\n');
Jakob Stoklund Olesen08e93b12010-08-10 17:07:22 +0000931 }
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000932}
933
934
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +0000935//===----------------------------------------------------------------------===//
936// Loop Splitting
937//===----------------------------------------------------------------------===//
938
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000939bool SplitEditor::splitAroundLoop(const MachineLoop *Loop) {
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000940 SplitAnalysis::LoopBlocks Blocks;
941 sa_.getLoopBlocks(Loop, Blocks);
942
943 // Break critical edges as needed.
944 SplitAnalysis::BlockPtrSet CriticalExits;
945 sa_.getCriticalExits(Blocks, CriticalExits);
946 assert(CriticalExits.empty() && "Cannot break critical exits yet");
947
948 // Create new live interval for the loop.
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000949 openIntv();
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000950
951 // Insert copies in the predecessors.
952 for (SplitAnalysis::BlockPtrSet::iterator I = Blocks.Preds.begin(),
953 E = Blocks.Preds.end(); I != E; ++I) {
954 MachineBasicBlock &MBB = const_cast<MachineBasicBlock&>(**I);
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000955 enterIntvAtEnd(MBB, *Loop->getHeader());
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000956 }
957
958 // Switch all loop blocks.
959 for (SplitAnalysis::BlockPtrSet::iterator I = Blocks.Loop.begin(),
960 E = Blocks.Loop.end(); I != E; ++I)
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000961 useIntv(**I);
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000962
963 // Insert back copies in the exit blocks.
964 for (SplitAnalysis::BlockPtrSet::iterator I = Blocks.Exits.begin(),
965 E = Blocks.Exits.end(); I != E; ++I) {
966 MachineBasicBlock &MBB = const_cast<MachineBasicBlock&>(**I);
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000967 leaveIntvAtTop(MBB);
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000968 }
969
970 // Done.
Jakob Stoklund Olesen7536f722010-08-04 22:08:39 +0000971 closeIntv();
Jakob Stoklund Olesenf0179002010-07-26 23:44:11 +0000972 rewrite();
Jakob Stoklund Olesen5eb308b2010-08-06 22:17:33 +0000973 return dupli_;
Jakob Stoklund Olesen8ae02632010-07-20 15:41:07 +0000974}
975
Jakob Stoklund Olesenf1b05f22010-08-12 17:07:14 +0000976
977//===----------------------------------------------------------------------===//
978// Single Block Splitting
979//===----------------------------------------------------------------------===//
980
981/// splitSingleBlocks - Split curli into a separate live interval inside each
982/// basic block in Blocks. Return true if curli has been completely replaced,
983/// false if curli is still intact, and needs to be spilled or split further.
984bool SplitEditor::splitSingleBlocks(const SplitAnalysis::BlockPtrSet &Blocks) {
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000985 DEBUG(dbgs() << " splitSingleBlocks for " << Blocks.size() << " blocks.\n");
Jakob Stoklund Olesenf1b05f22010-08-12 17:07:14 +0000986 // Determine the first and last instruction using curli in each block.
987 typedef std::pair<SlotIndex,SlotIndex> IndexPair;
988 typedef DenseMap<const MachineBasicBlock*,IndexPair> IndexPairMap;
989 IndexPairMap MBBRange;
990 for (SplitAnalysis::InstrPtrSet::const_iterator I = sa_.usingInstrs_.begin(),
991 E = sa_.usingInstrs_.end(); I != E; ++I) {
992 const MachineBasicBlock *MBB = (*I)->getParent();
993 if (!Blocks.count(MBB))
994 continue;
995 SlotIndex Idx = lis_.getInstructionIndex(*I);
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +0000996 DEBUG(dbgs() << " BB#" << MBB->getNumber() << '\t' << Idx << '\t' << **I);
Jakob Stoklund Olesenf1b05f22010-08-12 17:07:14 +0000997 IndexPair &IP = MBBRange[MBB];
998 if (!IP.first.isValid() || Idx < IP.first)
999 IP.first = Idx;
1000 if (!IP.second.isValid() || Idx > IP.second)
1001 IP.second = Idx;
1002 }
1003
1004 // Create a new interval for each block.
1005 for (SplitAnalysis::BlockPtrSet::const_iterator I = Blocks.begin(),
1006 E = Blocks.end(); I != E; ++I) {
1007 IndexPair &IP = MBBRange[*I];
Jakob Stoklund Olesene1f543f2010-08-12 18:50:55 +00001008 DEBUG(dbgs() << " splitting for BB#" << (*I)->getNumber() << ": ["
Jakob Stoklund Olesenf1b05f22010-08-12 17:07:14 +00001009 << IP.first << ';' << IP.second << ")\n");
1010 assert(IP.first.isValid() && IP.second.isValid());
1011
1012 openIntv();
1013 enterIntvBefore(IP.first);
1014 useIntv(IP.first.getBaseIndex(), IP.second.getBoundaryIndex());
1015 leaveIntvAfter(IP.second);
1016 closeIntv();
1017 }
1018 rewrite();
1019 return dupli_;
1020}
1021
Jakob Stoklund Olesenfc412d82010-08-13 21:18:48 +00001022
1023//===----------------------------------------------------------------------===//
1024// Sub Block Splitting
1025//===----------------------------------------------------------------------===//
1026
1027/// getBlockForInsideSplit - If curli is contained inside a single basic block,
1028/// and it wou pay to subdivide the interval inside that block, return it.
1029/// Otherwise return NULL. The returned block can be passed to
1030/// SplitEditor::splitInsideBlock.
1031const MachineBasicBlock *SplitAnalysis::getBlockForInsideSplit() {
1032 // The interval must be exclusive to one block.
1033 if (usingBlocks_.size() != 1)
1034 return 0;
1035 // Don't to this for less than 4 instructions. We want to be sure that
1036 // splitting actually reduces the instruction count per interval.
1037 if (usingInstrs_.size() < 4)
1038 return 0;
1039 return usingBlocks_.begin()->first;
1040}
1041
1042/// splitInsideBlock - Split curli into multiple intervals inside MBB. Return
1043/// true if curli has been completely replaced, false if curli is still
1044/// intact, and needs to be spilled or split further.
1045bool SplitEditor::splitInsideBlock(const MachineBasicBlock *MBB) {
1046 SmallVector<SlotIndex, 32> Uses;
1047 Uses.reserve(sa_.usingInstrs_.size());
1048 for (SplitAnalysis::InstrPtrSet::const_iterator I = sa_.usingInstrs_.begin(),
1049 E = sa_.usingInstrs_.end(); I != E; ++I)
1050 if ((*I)->getParent() == MBB)
1051 Uses.push_back(lis_.getInstructionIndex(*I));
1052 DEBUG(dbgs() << " splitInsideBlock BB#" << MBB->getNumber() << " for "
1053 << Uses.size() << " instructions.\n");
1054 assert(Uses.size() >= 3 && "Need at least 3 instructions");
1055 array_pod_sort(Uses.begin(), Uses.end());
1056
1057 // Simple algorithm: Find the largest gap between uses as determined by slot
1058 // indices. Create new intervals for instructions before the gap and after the
1059 // gap.
1060 unsigned bestPos = 0;
1061 int bestGap = 0;
1062 DEBUG(dbgs() << " dist (" << Uses[0]);
1063 for (unsigned i = 1, e = Uses.size(); i != e; ++i) {
1064 int g = Uses[i-1].distance(Uses[i]);
1065 DEBUG(dbgs() << ") -" << g << "- (" << Uses[i]);
1066 if (g > bestGap)
1067 bestPos = i, bestGap = g;
1068 }
1069 DEBUG(dbgs() << "), best: -" << bestGap << "-\n");
1070
1071 // bestPos points to the first use after the best gap.
1072 assert(bestPos > 0 && "Invalid gap");
1073
1074 // FIXME: Don't create intervals for low densities.
1075
1076 // First interval before the gap. Don't create single-instr intervals.
1077 if (bestPos > 1) {
1078 openIntv();
1079 enterIntvBefore(Uses.front());
1080 useIntv(Uses.front().getBaseIndex(), Uses[bestPos-1].getBoundaryIndex());
1081 leaveIntvAfter(Uses[bestPos-1]);
1082 closeIntv();
1083 }
1084
1085 // Second interval after the gap.
1086 if (bestPos < Uses.size()-1) {
1087 openIntv();
1088 enterIntvBefore(Uses[bestPos]);
1089 useIntv(Uses[bestPos].getBaseIndex(), Uses.back().getBoundaryIndex());
1090 leaveIntvAfter(Uses.back());
1091 closeIntv();
1092 }
1093
1094 rewrite();
1095 return dupli_;
1096}