File: | lib/Transforms/Scalar/LoopStrengthReduce.cpp |
Warning: | line 4153, column 5 Forming reference to null pointer |
1 | //===- LoopStrengthReduce.cpp - Strength Reduce IVs in Loops --------------===// | |||||||||
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 transformation analyzes and transforms the induction variables (and | |||||||||
11 | // computations derived from them) into forms suitable for efficient execution | |||||||||
12 | // on the target. | |||||||||
13 | // | |||||||||
14 | // This pass performs a strength reduction on array references inside loops that | |||||||||
15 | // have as one or more of their components the loop induction variable, it | |||||||||
16 | // rewrites expressions to take advantage of scaled-index addressing modes | |||||||||
17 | // available on the target, and it performs a variety of other optimizations | |||||||||
18 | // related to loop induction variables. | |||||||||
19 | // | |||||||||
20 | // Terminology note: this code has a lot of handling for "post-increment" or | |||||||||
21 | // "post-inc" users. This is not talking about post-increment addressing modes; | |||||||||
22 | // it is instead talking about code like this: | |||||||||
23 | // | |||||||||
24 | // %i = phi [ 0, %entry ], [ %i.next, %latch ] | |||||||||
25 | // ... | |||||||||
26 | // %i.next = add %i, 1 | |||||||||
27 | // %c = icmp eq %i.next, %n | |||||||||
28 | // | |||||||||
29 | // The SCEV for %i is {0,+,1}<%L>. The SCEV for %i.next is {1,+,1}<%L>, however | |||||||||
30 | // it's useful to think about these as the same register, with some uses using | |||||||||
31 | // the value of the register before the add and some using it after. In this | |||||||||
32 | // example, the icmp is a post-increment user, since it uses %i.next, which is | |||||||||
33 | // the value of the induction variable after the increment. The other common | |||||||||
34 | // case of post-increment users is users outside the loop. | |||||||||
35 | // | |||||||||
36 | // TODO: More sophistication in the way Formulae are generated and filtered. | |||||||||
37 | // | |||||||||
38 | // TODO: Handle multiple loops at a time. | |||||||||
39 | // | |||||||||
40 | // TODO: Should the addressing mode BaseGV be changed to a ConstantExpr instead | |||||||||
41 | // of a GlobalValue? | |||||||||
42 | // | |||||||||
43 | // TODO: When truncation is free, truncate ICmp users' operands to make it a | |||||||||
44 | // smaller encoding (on x86 at least). | |||||||||
45 | // | |||||||||
46 | // TODO: When a negated register is used by an add (such as in a list of | |||||||||
47 | // multiple base registers, or as the increment expression in an addrec), | |||||||||
48 | // we may not actually need both reg and (-1 * reg) in registers; the | |||||||||
49 | // negation can be implemented by using a sub instead of an add. The | |||||||||
50 | // lack of support for taking this into consideration when making | |||||||||
51 | // register pressure decisions is partly worked around by the "Special" | |||||||||
52 | // use kind. | |||||||||
53 | // | |||||||||
54 | //===----------------------------------------------------------------------===// | |||||||||
55 | ||||||||||
56 | #include "llvm/Transforms/Scalar/LoopStrengthReduce.h" | |||||||||
57 | #include "llvm/ADT/DenseSet.h" | |||||||||
58 | #include "llvm/ADT/Hashing.h" | |||||||||
59 | #include "llvm/ADT/STLExtras.h" | |||||||||
60 | #include "llvm/ADT/SetVector.h" | |||||||||
61 | #include "llvm/ADT/SmallBitVector.h" | |||||||||
62 | #include "llvm/Analysis/IVUsers.h" | |||||||||
63 | #include "llvm/Analysis/LoopPass.h" | |||||||||
64 | #include "llvm/Analysis/LoopPassManager.h" | |||||||||
65 | #include "llvm/Analysis/ScalarEvolutionExpander.h" | |||||||||
66 | #include "llvm/Analysis/TargetTransformInfo.h" | |||||||||
67 | #include "llvm/IR/Constants.h" | |||||||||
68 | #include "llvm/IR/DerivedTypes.h" | |||||||||
69 | #include "llvm/IR/Dominators.h" | |||||||||
70 | #include "llvm/IR/Instructions.h" | |||||||||
71 | #include "llvm/IR/IntrinsicInst.h" | |||||||||
72 | #include "llvm/IR/Module.h" | |||||||||
73 | #include "llvm/IR/ValueHandle.h" | |||||||||
74 | #include "llvm/Support/CommandLine.h" | |||||||||
75 | #include "llvm/Support/Debug.h" | |||||||||
76 | #include "llvm/Support/raw_ostream.h" | |||||||||
77 | #include "llvm/Transforms/Scalar.h" | |||||||||
78 | #include "llvm/Transforms/Utils/BasicBlockUtils.h" | |||||||||
79 | #include "llvm/Transforms/Utils/Local.h" | |||||||||
80 | #include <algorithm> | |||||||||
81 | using namespace llvm; | |||||||||
82 | ||||||||||
83 | #define DEBUG_TYPE"loop-reduce" "loop-reduce" | |||||||||
84 | ||||||||||
85 | /// MaxIVUsers is an arbitrary threshold that provides an early opportunitiy for | |||||||||
86 | /// bail out. This threshold is far beyond the number of users that LSR can | |||||||||
87 | /// conceivably solve, so it should not affect generated code, but catches the | |||||||||
88 | /// worst cases before LSR burns too much compile time and stack space. | |||||||||
89 | static const unsigned MaxIVUsers = 200; | |||||||||
90 | ||||||||||
91 | // Temporary flag to cleanup congruent phis after LSR phi expansion. | |||||||||
92 | // It's currently disabled until we can determine whether it's truly useful or | |||||||||
93 | // not. The flag should be removed after the v3.0 release. | |||||||||
94 | // This is now needed for ivchains. | |||||||||
95 | static cl::opt<bool> EnablePhiElim( | |||||||||
96 | "enable-lsr-phielim", cl::Hidden, cl::init(true), | |||||||||
97 | cl::desc("Enable LSR phi elimination")); | |||||||||
98 | ||||||||||
99 | #ifndef NDEBUG | |||||||||
100 | // Stress test IV chain generation. | |||||||||
101 | static cl::opt<bool> StressIVChain( | |||||||||
102 | "stress-ivchain", cl::Hidden, cl::init(false), | |||||||||
103 | cl::desc("Stress test LSR IV chains")); | |||||||||
104 | #else | |||||||||
105 | static bool StressIVChain = false; | |||||||||
106 | #endif | |||||||||
107 | ||||||||||
108 | namespace { | |||||||||
109 | ||||||||||
110 | struct MemAccessTy { | |||||||||
111 | /// Used in situations where the accessed memory type is unknown. | |||||||||
112 | static const unsigned UnknownAddressSpace = ~0u; | |||||||||
113 | ||||||||||
114 | Type *MemTy; | |||||||||
115 | unsigned AddrSpace; | |||||||||
116 | ||||||||||
117 | MemAccessTy() : MemTy(nullptr), AddrSpace(UnknownAddressSpace) {} | |||||||||
118 | ||||||||||
119 | MemAccessTy(Type *Ty, unsigned AS) : | |||||||||
120 | MemTy(Ty), AddrSpace(AS) {} | |||||||||
121 | ||||||||||
122 | bool operator==(MemAccessTy Other) const { | |||||||||
123 | return MemTy == Other.MemTy && AddrSpace == Other.AddrSpace; | |||||||||
124 | } | |||||||||
125 | ||||||||||
126 | bool operator!=(MemAccessTy Other) const { return !(*this == Other); } | |||||||||
127 | ||||||||||
128 | static MemAccessTy getUnknown(LLVMContext &Ctx) { | |||||||||
129 | return MemAccessTy(Type::getVoidTy(Ctx), UnknownAddressSpace); | |||||||||
130 | } | |||||||||
131 | }; | |||||||||
132 | ||||||||||
133 | /// This class holds data which is used to order reuse candidates. | |||||||||
134 | class RegSortData { | |||||||||
135 | public: | |||||||||
136 | /// This represents the set of LSRUse indices which reference | |||||||||
137 | /// a particular register. | |||||||||
138 | SmallBitVector UsedByIndices; | |||||||||
139 | ||||||||||
140 | void print(raw_ostream &OS) const; | |||||||||
141 | void dump() const; | |||||||||
142 | }; | |||||||||
143 | ||||||||||
144 | } | |||||||||
145 | ||||||||||
146 | void RegSortData::print(raw_ostream &OS) const { | |||||||||
147 | OS << "[NumUses=" << UsedByIndices.count() << ']'; | |||||||||
148 | } | |||||||||
149 | ||||||||||
150 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) | |||||||||
151 | void RegSortData::dump() const { | |||||||||
152 | print(errs()); errs() << '\n'; | |||||||||
153 | } | |||||||||
154 | ||||||||||
155 | namespace { | |||||||||
156 | ||||||||||
157 | /// Map register candidates to information about how they are used. | |||||||||
158 | class RegUseTracker { | |||||||||
159 | typedef DenseMap<const SCEV *, RegSortData> RegUsesTy; | |||||||||
160 | ||||||||||
161 | RegUsesTy RegUsesMap; | |||||||||
162 | SmallVector<const SCEV *, 16> RegSequence; | |||||||||
163 | ||||||||||
164 | public: | |||||||||
165 | void countRegister(const SCEV *Reg, size_t LUIdx); | |||||||||
166 | void dropRegister(const SCEV *Reg, size_t LUIdx); | |||||||||
167 | void swapAndDropUse(size_t LUIdx, size_t LastLUIdx); | |||||||||
168 | ||||||||||
169 | bool isRegUsedByUsesOtherThan(const SCEV *Reg, size_t LUIdx) const; | |||||||||
170 | ||||||||||
171 | const SmallBitVector &getUsedByIndices(const SCEV *Reg) const; | |||||||||
172 | ||||||||||
173 | void clear(); | |||||||||
174 | ||||||||||
175 | typedef SmallVectorImpl<const SCEV *>::iterator iterator; | |||||||||
176 | typedef SmallVectorImpl<const SCEV *>::const_iterator const_iterator; | |||||||||
177 | iterator begin() { return RegSequence.begin(); } | |||||||||
178 | iterator end() { return RegSequence.end(); } | |||||||||
179 | const_iterator begin() const { return RegSequence.begin(); } | |||||||||
180 | const_iterator end() const { return RegSequence.end(); } | |||||||||
181 | }; | |||||||||
182 | ||||||||||
183 | } | |||||||||
184 | ||||||||||
185 | void | |||||||||
186 | RegUseTracker::countRegister(const SCEV *Reg, size_t LUIdx) { | |||||||||
187 | std::pair<RegUsesTy::iterator, bool> Pair = | |||||||||
188 | RegUsesMap.insert(std::make_pair(Reg, RegSortData())); | |||||||||
189 | RegSortData &RSD = Pair.first->second; | |||||||||
190 | if (Pair.second) | |||||||||
191 | RegSequence.push_back(Reg); | |||||||||
192 | RSD.UsedByIndices.resize(std::max(RSD.UsedByIndices.size(), LUIdx + 1)); | |||||||||
193 | RSD.UsedByIndices.set(LUIdx); | |||||||||
194 | } | |||||||||
195 | ||||||||||
196 | void | |||||||||
197 | RegUseTracker::dropRegister(const SCEV *Reg, size_t LUIdx) { | |||||||||
198 | RegUsesTy::iterator It = RegUsesMap.find(Reg); | |||||||||
199 | assert(It != RegUsesMap.end())((It != RegUsesMap.end()) ? static_cast<void> (0) : __assert_fail ("It != RegUsesMap.end()", "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 199, __PRETTY_FUNCTION__)); | |||||||||
200 | RegSortData &RSD = It->second; | |||||||||
201 | assert(RSD.UsedByIndices.size() > LUIdx)((RSD.UsedByIndices.size() > LUIdx) ? static_cast<void> (0) : __assert_fail ("RSD.UsedByIndices.size() > LUIdx", "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 201, __PRETTY_FUNCTION__)); | |||||||||
202 | RSD.UsedByIndices.reset(LUIdx); | |||||||||
203 | } | |||||||||
204 | ||||||||||
205 | void | |||||||||
206 | RegUseTracker::swapAndDropUse(size_t LUIdx, size_t LastLUIdx) { | |||||||||
207 | assert(LUIdx <= LastLUIdx)((LUIdx <= LastLUIdx) ? static_cast<void> (0) : __assert_fail ("LUIdx <= LastLUIdx", "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 207, __PRETTY_FUNCTION__)); | |||||||||
208 | ||||||||||
209 | // Update RegUses. The data structure is not optimized for this purpose; | |||||||||
210 | // we must iterate through it and update each of the bit vectors. | |||||||||
211 | for (auto &Pair : RegUsesMap) { | |||||||||
212 | SmallBitVector &UsedByIndices = Pair.second.UsedByIndices; | |||||||||
213 | if (LUIdx < UsedByIndices.size()) | |||||||||
214 | UsedByIndices[LUIdx] = | |||||||||
215 | LastLUIdx < UsedByIndices.size() ? UsedByIndices[LastLUIdx] : 0; | |||||||||
216 | UsedByIndices.resize(std::min(UsedByIndices.size(), LastLUIdx)); | |||||||||
217 | } | |||||||||
218 | } | |||||||||
219 | ||||||||||
220 | bool | |||||||||
221 | RegUseTracker::isRegUsedByUsesOtherThan(const SCEV *Reg, size_t LUIdx) const { | |||||||||
222 | RegUsesTy::const_iterator I = RegUsesMap.find(Reg); | |||||||||
223 | if (I == RegUsesMap.end()) | |||||||||
224 | return false; | |||||||||
225 | const SmallBitVector &UsedByIndices = I->second.UsedByIndices; | |||||||||
226 | int i = UsedByIndices.find_first(); | |||||||||
227 | if (i == -1) return false; | |||||||||
228 | if ((size_t)i != LUIdx) return true; | |||||||||
229 | return UsedByIndices.find_next(i) != -1; | |||||||||
230 | } | |||||||||
231 | ||||||||||
232 | const SmallBitVector &RegUseTracker::getUsedByIndices(const SCEV *Reg) const { | |||||||||
233 | RegUsesTy::const_iterator I = RegUsesMap.find(Reg); | |||||||||
234 | assert(I != RegUsesMap.end() && "Unknown register!")((I != RegUsesMap.end() && "Unknown register!") ? static_cast <void> (0) : __assert_fail ("I != RegUsesMap.end() && \"Unknown register!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 234, __PRETTY_FUNCTION__)); | |||||||||
235 | return I->second.UsedByIndices; | |||||||||
236 | } | |||||||||
237 | ||||||||||
238 | void RegUseTracker::clear() { | |||||||||
239 | RegUsesMap.clear(); | |||||||||
240 | RegSequence.clear(); | |||||||||
241 | } | |||||||||
242 | ||||||||||
243 | namespace { | |||||||||
244 | ||||||||||
245 | /// This class holds information that describes a formula for computing | |||||||||
246 | /// satisfying a use. It may include broken-out immediates and scaled registers. | |||||||||
247 | struct Formula { | |||||||||
248 | /// Global base address used for complex addressing. | |||||||||
249 | GlobalValue *BaseGV; | |||||||||
250 | ||||||||||
251 | /// Base offset for complex addressing. | |||||||||
252 | int64_t BaseOffset; | |||||||||
253 | ||||||||||
254 | /// Whether any complex addressing has a base register. | |||||||||
255 | bool HasBaseReg; | |||||||||
256 | ||||||||||
257 | /// The scale of any complex addressing. | |||||||||
258 | int64_t Scale; | |||||||||
259 | ||||||||||
260 | /// The list of "base" registers for this use. When this is non-empty. The | |||||||||
261 | /// canonical representation of a formula is | |||||||||
262 | /// 1. BaseRegs.size > 1 implies ScaledReg != NULL and | |||||||||
263 | /// 2. ScaledReg != NULL implies Scale != 1 || !BaseRegs.empty(). | |||||||||
264 | /// #1 enforces that the scaled register is always used when at least two | |||||||||
265 | /// registers are needed by the formula: e.g., reg1 + reg2 is reg1 + 1 * reg2. | |||||||||
266 | /// #2 enforces that 1 * reg is reg. | |||||||||
267 | /// This invariant can be temporarly broken while building a formula. | |||||||||
268 | /// However, every formula inserted into the LSRInstance must be in canonical | |||||||||
269 | /// form. | |||||||||
270 | SmallVector<const SCEV *, 4> BaseRegs; | |||||||||
271 | ||||||||||
272 | /// The 'scaled' register for this use. This should be non-null when Scale is | |||||||||
273 | /// not zero. | |||||||||
274 | const SCEV *ScaledReg; | |||||||||
275 | ||||||||||
276 | /// An additional constant offset which added near the use. This requires a | |||||||||
277 | /// temporary register, but the offset itself can live in an add immediate | |||||||||
278 | /// field rather than a register. | |||||||||
279 | int64_t UnfoldedOffset; | |||||||||
280 | ||||||||||
281 | Formula() | |||||||||
282 | : BaseGV(nullptr), BaseOffset(0), HasBaseReg(false), Scale(0), | |||||||||
283 | ScaledReg(nullptr), UnfoldedOffset(0) {} | |||||||||
284 | ||||||||||
285 | void initialMatch(const SCEV *S, Loop *L, ScalarEvolution &SE); | |||||||||
286 | ||||||||||
287 | bool isCanonical() const; | |||||||||
288 | ||||||||||
289 | void canonicalize(); | |||||||||
290 | ||||||||||
291 | bool unscale(); | |||||||||
292 | ||||||||||
293 | size_t getNumRegs() const; | |||||||||
294 | Type *getType() const; | |||||||||
295 | ||||||||||
296 | void deleteBaseReg(const SCEV *&S); | |||||||||
297 | ||||||||||
298 | bool referencesReg(const SCEV *S) const; | |||||||||
299 | bool hasRegsUsedByUsesOtherThan(size_t LUIdx, | |||||||||
300 | const RegUseTracker &RegUses) const; | |||||||||
301 | ||||||||||
302 | void print(raw_ostream &OS) const; | |||||||||
303 | void dump() const; | |||||||||
304 | }; | |||||||||
305 | ||||||||||
306 | } | |||||||||
307 | ||||||||||
308 | /// Recursion helper for initialMatch. | |||||||||
309 | static void DoInitialMatch(const SCEV *S, Loop *L, | |||||||||
310 | SmallVectorImpl<const SCEV *> &Good, | |||||||||
311 | SmallVectorImpl<const SCEV *> &Bad, | |||||||||
312 | ScalarEvolution &SE) { | |||||||||
313 | // Collect expressions which properly dominate the loop header. | |||||||||
314 | if (SE.properlyDominates(S, L->getHeader())) { | |||||||||
315 | Good.push_back(S); | |||||||||
316 | return; | |||||||||
317 | } | |||||||||
318 | ||||||||||
319 | // Look at add operands. | |||||||||
320 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) { | |||||||||
321 | for (const SCEV *S : Add->operands()) | |||||||||
322 | DoInitialMatch(S, L, Good, Bad, SE); | |||||||||
323 | return; | |||||||||
324 | } | |||||||||
325 | ||||||||||
326 | // Look at addrec operands. | |||||||||
327 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) | |||||||||
328 | if (!AR->getStart()->isZero()) { | |||||||||
329 | DoInitialMatch(AR->getStart(), L, Good, Bad, SE); | |||||||||
330 | DoInitialMatch(SE.getAddRecExpr(SE.getConstant(AR->getType(), 0), | |||||||||
331 | AR->getStepRecurrence(SE), | |||||||||
332 | // FIXME: AR->getNoWrapFlags() | |||||||||
333 | AR->getLoop(), SCEV::FlagAnyWrap), | |||||||||
334 | L, Good, Bad, SE); | |||||||||
335 | return; | |||||||||
336 | } | |||||||||
337 | ||||||||||
338 | // Handle a multiplication by -1 (negation) if it didn't fold. | |||||||||
339 | if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) | |||||||||
340 | if (Mul->getOperand(0)->isAllOnesValue()) { | |||||||||
341 | SmallVector<const SCEV *, 4> Ops(Mul->op_begin()+1, Mul->op_end()); | |||||||||
342 | const SCEV *NewMul = SE.getMulExpr(Ops); | |||||||||
343 | ||||||||||
344 | SmallVector<const SCEV *, 4> MyGood; | |||||||||
345 | SmallVector<const SCEV *, 4> MyBad; | |||||||||
346 | DoInitialMatch(NewMul, L, MyGood, MyBad, SE); | |||||||||
347 | const SCEV *NegOne = SE.getSCEV(ConstantInt::getAllOnesValue( | |||||||||
348 | SE.getEffectiveSCEVType(NewMul->getType()))); | |||||||||
349 | for (const SCEV *S : MyGood) | |||||||||
350 | Good.push_back(SE.getMulExpr(NegOne, S)); | |||||||||
351 | for (const SCEV *S : MyBad) | |||||||||
352 | Bad.push_back(SE.getMulExpr(NegOne, S)); | |||||||||
353 | return; | |||||||||
354 | } | |||||||||
355 | ||||||||||
356 | // Ok, we can't do anything interesting. Just stuff the whole thing into a | |||||||||
357 | // register and hope for the best. | |||||||||
358 | Bad.push_back(S); | |||||||||
359 | } | |||||||||
360 | ||||||||||
361 | /// Incorporate loop-variant parts of S into this Formula, attempting to keep | |||||||||
362 | /// all loop-invariant and loop-computable values in a single base register. | |||||||||
363 | void Formula::initialMatch(const SCEV *S, Loop *L, ScalarEvolution &SE) { | |||||||||
364 | SmallVector<const SCEV *, 4> Good; | |||||||||
365 | SmallVector<const SCEV *, 4> Bad; | |||||||||
366 | DoInitialMatch(S, L, Good, Bad, SE); | |||||||||
367 | if (!Good.empty()) { | |||||||||
368 | const SCEV *Sum = SE.getAddExpr(Good); | |||||||||
369 | if (!Sum->isZero()) | |||||||||
370 | BaseRegs.push_back(Sum); | |||||||||
371 | HasBaseReg = true; | |||||||||
372 | } | |||||||||
373 | if (!Bad.empty()) { | |||||||||
374 | const SCEV *Sum = SE.getAddExpr(Bad); | |||||||||
375 | if (!Sum->isZero()) | |||||||||
376 | BaseRegs.push_back(Sum); | |||||||||
377 | HasBaseReg = true; | |||||||||
378 | } | |||||||||
379 | canonicalize(); | |||||||||
380 | } | |||||||||
381 | ||||||||||
382 | /// \brief Check whether or not this formula statisfies the canonical | |||||||||
383 | /// representation. | |||||||||
384 | /// \see Formula::BaseRegs. | |||||||||
385 | bool Formula::isCanonical() const { | |||||||||
386 | if (ScaledReg) | |||||||||
387 | return Scale != 1 || !BaseRegs.empty(); | |||||||||
388 | return BaseRegs.size() <= 1; | |||||||||
389 | } | |||||||||
390 | ||||||||||
391 | /// \brief Helper method to morph a formula into its canonical representation. | |||||||||
392 | /// \see Formula::BaseRegs. | |||||||||
393 | /// Every formula having more than one base register, must use the ScaledReg | |||||||||
394 | /// field. Otherwise, we would have to do special cases everywhere in LSR | |||||||||
395 | /// to treat reg1 + reg2 + ... the same way as reg1 + 1*reg2 + ... | |||||||||
396 | /// On the other hand, 1*reg should be canonicalized into reg. | |||||||||
397 | void Formula::canonicalize() { | |||||||||
398 | if (isCanonical()) | |||||||||
399 | return; | |||||||||
400 | // So far we did not need this case. This is easy to implement but it is | |||||||||
401 | // useless to maintain dead code. Beside it could hurt compile time. | |||||||||
402 | assert(!BaseRegs.empty() && "1*reg => reg, should not be needed.")((!BaseRegs.empty() && "1*reg => reg, should not be needed." ) ? static_cast<void> (0) : __assert_fail ("!BaseRegs.empty() && \"1*reg => reg, should not be needed.\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 402, __PRETTY_FUNCTION__)); | |||||||||
403 | // Keep the invariant sum in BaseRegs and one of the variant sum in ScaledReg. | |||||||||
404 | ScaledReg = BaseRegs.back(); | |||||||||
405 | BaseRegs.pop_back(); | |||||||||
406 | Scale = 1; | |||||||||
407 | size_t BaseRegsSize = BaseRegs.size(); | |||||||||
408 | size_t Try = 0; | |||||||||
409 | // If ScaledReg is an invariant, try to find a variant expression. | |||||||||
410 | while (Try < BaseRegsSize && !isa<SCEVAddRecExpr>(ScaledReg)) | |||||||||
411 | std::swap(ScaledReg, BaseRegs[Try++]); | |||||||||
412 | } | |||||||||
413 | ||||||||||
414 | /// \brief Get rid of the scale in the formula. | |||||||||
415 | /// In other words, this method morphes reg1 + 1*reg2 into reg1 + reg2. | |||||||||
416 | /// \return true if it was possible to get rid of the scale, false otherwise. | |||||||||
417 | /// \note After this operation the formula may not be in the canonical form. | |||||||||
418 | bool Formula::unscale() { | |||||||||
419 | if (Scale != 1) | |||||||||
420 | return false; | |||||||||
421 | Scale = 0; | |||||||||
422 | BaseRegs.push_back(ScaledReg); | |||||||||
423 | ScaledReg = nullptr; | |||||||||
424 | return true; | |||||||||
425 | } | |||||||||
426 | ||||||||||
427 | /// Return the total number of register operands used by this formula. This does | |||||||||
428 | /// not include register uses implied by non-constant addrec strides. | |||||||||
429 | size_t Formula::getNumRegs() const { | |||||||||
430 | return !!ScaledReg + BaseRegs.size(); | |||||||||
431 | } | |||||||||
432 | ||||||||||
433 | /// Return the type of this formula, if it has one, or null otherwise. This type | |||||||||
434 | /// is meaningless except for the bit size. | |||||||||
435 | Type *Formula::getType() const { | |||||||||
436 | return !BaseRegs.empty() ? BaseRegs.front()->getType() : | |||||||||
437 | ScaledReg ? ScaledReg->getType() : | |||||||||
438 | BaseGV ? BaseGV->getType() : | |||||||||
439 | nullptr; | |||||||||
440 | } | |||||||||
441 | ||||||||||
442 | /// Delete the given base reg from the BaseRegs list. | |||||||||
443 | void Formula::deleteBaseReg(const SCEV *&S) { | |||||||||
444 | if (&S != &BaseRegs.back()) | |||||||||
445 | std::swap(S, BaseRegs.back()); | |||||||||
446 | BaseRegs.pop_back(); | |||||||||
447 | } | |||||||||
448 | ||||||||||
449 | /// Test if this formula references the given register. | |||||||||
450 | bool Formula::referencesReg(const SCEV *S) const { | |||||||||
451 | return S == ScaledReg || is_contained(BaseRegs, S); | |||||||||
452 | } | |||||||||
453 | ||||||||||
454 | /// Test whether this formula uses registers which are used by uses other than | |||||||||
455 | /// the use with the given index. | |||||||||
456 | bool Formula::hasRegsUsedByUsesOtherThan(size_t LUIdx, | |||||||||
457 | const RegUseTracker &RegUses) const { | |||||||||
458 | if (ScaledReg) | |||||||||
459 | if (RegUses.isRegUsedByUsesOtherThan(ScaledReg, LUIdx)) | |||||||||
460 | return true; | |||||||||
461 | for (const SCEV *BaseReg : BaseRegs) | |||||||||
462 | if (RegUses.isRegUsedByUsesOtherThan(BaseReg, LUIdx)) | |||||||||
463 | return true; | |||||||||
464 | return false; | |||||||||
465 | } | |||||||||
466 | ||||||||||
467 | void Formula::print(raw_ostream &OS) const { | |||||||||
468 | bool First = true; | |||||||||
469 | if (BaseGV) { | |||||||||
470 | if (!First) OS << " + "; else First = false; | |||||||||
471 | BaseGV->printAsOperand(OS, /*PrintType=*/false); | |||||||||
472 | } | |||||||||
473 | if (BaseOffset != 0) { | |||||||||
474 | if (!First) OS << " + "; else First = false; | |||||||||
475 | OS << BaseOffset; | |||||||||
476 | } | |||||||||
477 | for (const SCEV *BaseReg : BaseRegs) { | |||||||||
478 | if (!First) OS << " + "; else First = false; | |||||||||
479 | OS << "reg(" << *BaseReg << ')'; | |||||||||
480 | } | |||||||||
481 | if (HasBaseReg && BaseRegs.empty()) { | |||||||||
482 | if (!First) OS << " + "; else First = false; | |||||||||
483 | OS << "**error: HasBaseReg**"; | |||||||||
484 | } else if (!HasBaseReg && !BaseRegs.empty()) { | |||||||||
485 | if (!First) OS << " + "; else First = false; | |||||||||
486 | OS << "**error: !HasBaseReg**"; | |||||||||
487 | } | |||||||||
488 | if (Scale != 0) { | |||||||||
489 | if (!First) OS << " + "; else First = false; | |||||||||
490 | OS << Scale << "*reg("; | |||||||||
491 | if (ScaledReg) | |||||||||
492 | OS << *ScaledReg; | |||||||||
493 | else | |||||||||
494 | OS << "<unknown>"; | |||||||||
495 | OS << ')'; | |||||||||
496 | } | |||||||||
497 | if (UnfoldedOffset != 0) { | |||||||||
498 | if (!First) OS << " + "; | |||||||||
499 | OS << "imm(" << UnfoldedOffset << ')'; | |||||||||
500 | } | |||||||||
501 | } | |||||||||
502 | ||||||||||
503 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) | |||||||||
504 | void Formula::dump() const { | |||||||||
505 | print(errs()); errs() << '\n'; | |||||||||
506 | } | |||||||||
507 | ||||||||||
508 | /// Return true if the given addrec can be sign-extended without changing its | |||||||||
509 | /// value. | |||||||||
510 | static bool isAddRecSExtable(const SCEVAddRecExpr *AR, ScalarEvolution &SE) { | |||||||||
511 | Type *WideTy = | |||||||||
512 | IntegerType::get(SE.getContext(), SE.getTypeSizeInBits(AR->getType()) + 1); | |||||||||
513 | return isa<SCEVAddRecExpr>(SE.getSignExtendExpr(AR, WideTy)); | |||||||||
514 | } | |||||||||
515 | ||||||||||
516 | /// Return true if the given add can be sign-extended without changing its | |||||||||
517 | /// value. | |||||||||
518 | static bool isAddSExtable(const SCEVAddExpr *A, ScalarEvolution &SE) { | |||||||||
519 | Type *WideTy = | |||||||||
520 | IntegerType::get(SE.getContext(), SE.getTypeSizeInBits(A->getType()) + 1); | |||||||||
521 | return isa<SCEVAddExpr>(SE.getSignExtendExpr(A, WideTy)); | |||||||||
522 | } | |||||||||
523 | ||||||||||
524 | /// Return true if the given mul can be sign-extended without changing its | |||||||||
525 | /// value. | |||||||||
526 | static bool isMulSExtable(const SCEVMulExpr *M, ScalarEvolution &SE) { | |||||||||
527 | Type *WideTy = | |||||||||
528 | IntegerType::get(SE.getContext(), | |||||||||
529 | SE.getTypeSizeInBits(M->getType()) * M->getNumOperands()); | |||||||||
530 | return isa<SCEVMulExpr>(SE.getSignExtendExpr(M, WideTy)); | |||||||||
531 | } | |||||||||
532 | ||||||||||
533 | /// Return an expression for LHS /s RHS, if it can be determined and if the | |||||||||
534 | /// remainder is known to be zero, or null otherwise. If IgnoreSignificantBits | |||||||||
535 | /// is true, expressions like (X * Y) /s Y are simplified to Y, ignoring that | |||||||||
536 | /// the multiplication may overflow, which is useful when the result will be | |||||||||
537 | /// used in a context where the most significant bits are ignored. | |||||||||
538 | static const SCEV *getExactSDiv(const SCEV *LHS, const SCEV *RHS, | |||||||||
539 | ScalarEvolution &SE, | |||||||||
540 | bool IgnoreSignificantBits = false) { | |||||||||
541 | // Handle the trivial case, which works for any SCEV type. | |||||||||
542 | if (LHS == RHS) | |||||||||
543 | return SE.getConstant(LHS->getType(), 1); | |||||||||
544 | ||||||||||
545 | // Handle a few RHS special cases. | |||||||||
546 | const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS); | |||||||||
547 | if (RC) { | |||||||||
548 | const APInt &RA = RC->getAPInt(); | |||||||||
549 | // Handle x /s -1 as x * -1, to give ScalarEvolution a chance to do | |||||||||
550 | // some folding. | |||||||||
551 | if (RA.isAllOnesValue()) | |||||||||
552 | return SE.getMulExpr(LHS, RC); | |||||||||
553 | // Handle x /s 1 as x. | |||||||||
554 | if (RA == 1) | |||||||||
555 | return LHS; | |||||||||
556 | } | |||||||||
557 | ||||||||||
558 | // Check for a division of a constant by a constant. | |||||||||
559 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(LHS)) { | |||||||||
560 | if (!RC) | |||||||||
561 | return nullptr; | |||||||||
562 | const APInt &LA = C->getAPInt(); | |||||||||
563 | const APInt &RA = RC->getAPInt(); | |||||||||
564 | if (LA.srem(RA) != 0) | |||||||||
565 | return nullptr; | |||||||||
566 | return SE.getConstant(LA.sdiv(RA)); | |||||||||
567 | } | |||||||||
568 | ||||||||||
569 | // Distribute the sdiv over addrec operands, if the addrec doesn't overflow. | |||||||||
570 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS)) { | |||||||||
571 | if (IgnoreSignificantBits || isAddRecSExtable(AR, SE)) { | |||||||||
572 | const SCEV *Step = getExactSDiv(AR->getStepRecurrence(SE), RHS, SE, | |||||||||
573 | IgnoreSignificantBits); | |||||||||
574 | if (!Step) return nullptr; | |||||||||
575 | const SCEV *Start = getExactSDiv(AR->getStart(), RHS, SE, | |||||||||
576 | IgnoreSignificantBits); | |||||||||
577 | if (!Start) return nullptr; | |||||||||
578 | // FlagNW is independent of the start value, step direction, and is | |||||||||
579 | // preserved with smaller magnitude steps. | |||||||||
580 | // FIXME: AR->getNoWrapFlags(SCEV::FlagNW) | |||||||||
581 | return SE.getAddRecExpr(Start, Step, AR->getLoop(), SCEV::FlagAnyWrap); | |||||||||
582 | } | |||||||||
583 | return nullptr; | |||||||||
584 | } | |||||||||
585 | ||||||||||
586 | // Distribute the sdiv over add operands, if the add doesn't overflow. | |||||||||
587 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(LHS)) { | |||||||||
588 | if (IgnoreSignificantBits || isAddSExtable(Add, SE)) { | |||||||||
589 | SmallVector<const SCEV *, 8> Ops; | |||||||||
590 | for (const SCEV *S : Add->operands()) { | |||||||||
591 | const SCEV *Op = getExactSDiv(S, RHS, SE, IgnoreSignificantBits); | |||||||||
592 | if (!Op) return nullptr; | |||||||||
593 | Ops.push_back(Op); | |||||||||
594 | } | |||||||||
595 | return SE.getAddExpr(Ops); | |||||||||
596 | } | |||||||||
597 | return nullptr; | |||||||||
598 | } | |||||||||
599 | ||||||||||
600 | // Check for a multiply operand that we can pull RHS out of. | |||||||||
601 | if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS)) { | |||||||||
602 | if (IgnoreSignificantBits || isMulSExtable(Mul, SE)) { | |||||||||
603 | SmallVector<const SCEV *, 4> Ops; | |||||||||
604 | bool Found = false; | |||||||||
605 | for (const SCEV *S : Mul->operands()) { | |||||||||
606 | if (!Found) | |||||||||
607 | if (const SCEV *Q = getExactSDiv(S, RHS, SE, | |||||||||
608 | IgnoreSignificantBits)) { | |||||||||
609 | S = Q; | |||||||||
610 | Found = true; | |||||||||
611 | } | |||||||||
612 | Ops.push_back(S); | |||||||||
613 | } | |||||||||
614 | return Found ? SE.getMulExpr(Ops) : nullptr; | |||||||||
615 | } | |||||||||
616 | return nullptr; | |||||||||
617 | } | |||||||||
618 | ||||||||||
619 | // Otherwise we don't know. | |||||||||
620 | return nullptr; | |||||||||
621 | } | |||||||||
622 | ||||||||||
623 | /// If S involves the addition of a constant integer value, return that integer | |||||||||
624 | /// value, and mutate S to point to a new SCEV with that value excluded. | |||||||||
625 | static int64_t ExtractImmediate(const SCEV *&S, ScalarEvolution &SE) { | |||||||||
626 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) { | |||||||||
627 | if (C->getAPInt().getMinSignedBits() <= 64) { | |||||||||
628 | S = SE.getConstant(C->getType(), 0); | |||||||||
629 | return C->getValue()->getSExtValue(); | |||||||||
630 | } | |||||||||
631 | } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) { | |||||||||
632 | SmallVector<const SCEV *, 8> NewOps(Add->op_begin(), Add->op_end()); | |||||||||
633 | int64_t Result = ExtractImmediate(NewOps.front(), SE); | |||||||||
634 | if (Result != 0) | |||||||||
635 | S = SE.getAddExpr(NewOps); | |||||||||
636 | return Result; | |||||||||
637 | } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) { | |||||||||
638 | SmallVector<const SCEV *, 8> NewOps(AR->op_begin(), AR->op_end()); | |||||||||
639 | int64_t Result = ExtractImmediate(NewOps.front(), SE); | |||||||||
640 | if (Result != 0) | |||||||||
641 | S = SE.getAddRecExpr(NewOps, AR->getLoop(), | |||||||||
642 | // FIXME: AR->getNoWrapFlags(SCEV::FlagNW) | |||||||||
643 | SCEV::FlagAnyWrap); | |||||||||
644 | return Result; | |||||||||
645 | } | |||||||||
646 | return 0; | |||||||||
647 | } | |||||||||
648 | ||||||||||
649 | /// If S involves the addition of a GlobalValue address, return that symbol, and | |||||||||
650 | /// mutate S to point to a new SCEV with that value excluded. | |||||||||
651 | static GlobalValue *ExtractSymbol(const SCEV *&S, ScalarEvolution &SE) { | |||||||||
652 | if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) { | |||||||||
653 | if (GlobalValue *GV = dyn_cast<GlobalValue>(U->getValue())) { | |||||||||
654 | S = SE.getConstant(GV->getType(), 0); | |||||||||
655 | return GV; | |||||||||
656 | } | |||||||||
657 | } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) { | |||||||||
658 | SmallVector<const SCEV *, 8> NewOps(Add->op_begin(), Add->op_end()); | |||||||||
659 | GlobalValue *Result = ExtractSymbol(NewOps.back(), SE); | |||||||||
660 | if (Result) | |||||||||
661 | S = SE.getAddExpr(NewOps); | |||||||||
662 | return Result; | |||||||||
663 | } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) { | |||||||||
664 | SmallVector<const SCEV *, 8> NewOps(AR->op_begin(), AR->op_end()); | |||||||||
665 | GlobalValue *Result = ExtractSymbol(NewOps.front(), SE); | |||||||||
666 | if (Result) | |||||||||
667 | S = SE.getAddRecExpr(NewOps, AR->getLoop(), | |||||||||
668 | // FIXME: AR->getNoWrapFlags(SCEV::FlagNW) | |||||||||
669 | SCEV::FlagAnyWrap); | |||||||||
670 | return Result; | |||||||||
671 | } | |||||||||
672 | return nullptr; | |||||||||
673 | } | |||||||||
674 | ||||||||||
675 | /// Returns true if the specified instruction is using the specified value as an | |||||||||
676 | /// address. | |||||||||
677 | static bool isAddressUse(Instruction *Inst, Value *OperandVal) { | |||||||||
678 | bool isAddress = isa<LoadInst>(Inst); | |||||||||
679 | if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) { | |||||||||
680 | if (SI->getOperand(1) == OperandVal) | |||||||||
681 | isAddress = true; | |||||||||
682 | } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) { | |||||||||
683 | // Addressing modes can also be folded into prefetches and a variety | |||||||||
684 | // of intrinsics. | |||||||||
685 | switch (II->getIntrinsicID()) { | |||||||||
686 | default: break; | |||||||||
687 | case Intrinsic::prefetch: | |||||||||
688 | if (II->getArgOperand(0) == OperandVal) | |||||||||
689 | isAddress = true; | |||||||||
690 | break; | |||||||||
691 | } | |||||||||
692 | } | |||||||||
693 | return isAddress; | |||||||||
694 | } | |||||||||
695 | ||||||||||
696 | /// Return the type of the memory being accessed. | |||||||||
697 | static MemAccessTy getAccessType(const Instruction *Inst) { | |||||||||
698 | MemAccessTy AccessTy(Inst->getType(), MemAccessTy::UnknownAddressSpace); | |||||||||
699 | if (const StoreInst *SI = dyn_cast<StoreInst>(Inst)) { | |||||||||
700 | AccessTy.MemTy = SI->getOperand(0)->getType(); | |||||||||
701 | AccessTy.AddrSpace = SI->getPointerAddressSpace(); | |||||||||
702 | } else if (const LoadInst *LI = dyn_cast<LoadInst>(Inst)) { | |||||||||
703 | AccessTy.AddrSpace = LI->getPointerAddressSpace(); | |||||||||
704 | } | |||||||||
705 | ||||||||||
706 | // All pointers have the same requirements, so canonicalize them to an | |||||||||
707 | // arbitrary pointer type to minimize variation. | |||||||||
708 | if (PointerType *PTy = dyn_cast<PointerType>(AccessTy.MemTy)) | |||||||||
709 | AccessTy.MemTy = PointerType::get(IntegerType::get(PTy->getContext(), 1), | |||||||||
710 | PTy->getAddressSpace()); | |||||||||
711 | ||||||||||
712 | return AccessTy; | |||||||||
713 | } | |||||||||
714 | ||||||||||
715 | /// Return true if this AddRec is already a phi in its loop. | |||||||||
716 | static bool isExistingPhi(const SCEVAddRecExpr *AR, ScalarEvolution &SE) { | |||||||||
717 | for (BasicBlock::iterator I = AR->getLoop()->getHeader()->begin(); | |||||||||
718 | PHINode *PN = dyn_cast<PHINode>(I); ++I) { | |||||||||
719 | if (SE.isSCEVable(PN->getType()) && | |||||||||
720 | (SE.getEffectiveSCEVType(PN->getType()) == | |||||||||
721 | SE.getEffectiveSCEVType(AR->getType())) && | |||||||||
722 | SE.getSCEV(PN) == AR) | |||||||||
723 | return true; | |||||||||
724 | } | |||||||||
725 | return false; | |||||||||
726 | } | |||||||||
727 | ||||||||||
728 | /// Check if expanding this expression is likely to incur significant cost. This | |||||||||
729 | /// is tricky because SCEV doesn't track which expressions are actually computed | |||||||||
730 | /// by the current IR. | |||||||||
731 | /// | |||||||||
732 | /// We currently allow expansion of IV increments that involve adds, | |||||||||
733 | /// multiplication by constants, and AddRecs from existing phis. | |||||||||
734 | /// | |||||||||
735 | /// TODO: Allow UDivExpr if we can find an existing IV increment that is an | |||||||||
736 | /// obvious multiple of the UDivExpr. | |||||||||
737 | static bool isHighCostExpansion(const SCEV *S, | |||||||||
738 | SmallPtrSetImpl<const SCEV*> &Processed, | |||||||||
739 | ScalarEvolution &SE) { | |||||||||
740 | // Zero/One operand expressions | |||||||||
741 | switch (S->getSCEVType()) { | |||||||||
742 | case scUnknown: | |||||||||
743 | case scConstant: | |||||||||
744 | return false; | |||||||||
745 | case scTruncate: | |||||||||
746 | return isHighCostExpansion(cast<SCEVTruncateExpr>(S)->getOperand(), | |||||||||
747 | Processed, SE); | |||||||||
748 | case scZeroExtend: | |||||||||
749 | return isHighCostExpansion(cast<SCEVZeroExtendExpr>(S)->getOperand(), | |||||||||
750 | Processed, SE); | |||||||||
751 | case scSignExtend: | |||||||||
752 | return isHighCostExpansion(cast<SCEVSignExtendExpr>(S)->getOperand(), | |||||||||
753 | Processed, SE); | |||||||||
754 | } | |||||||||
755 | ||||||||||
756 | if (!Processed.insert(S).second) | |||||||||
757 | return false; | |||||||||
758 | ||||||||||
759 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) { | |||||||||
760 | for (const SCEV *S : Add->operands()) { | |||||||||
761 | if (isHighCostExpansion(S, Processed, SE)) | |||||||||
762 | return true; | |||||||||
763 | } | |||||||||
764 | return false; | |||||||||
765 | } | |||||||||
766 | ||||||||||
767 | if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) { | |||||||||
768 | if (Mul->getNumOperands() == 2) { | |||||||||
769 | // Multiplication by a constant is ok | |||||||||
770 | if (isa<SCEVConstant>(Mul->getOperand(0))) | |||||||||
771 | return isHighCostExpansion(Mul->getOperand(1), Processed, SE); | |||||||||
772 | ||||||||||
773 | // If we have the value of one operand, check if an existing | |||||||||
774 | // multiplication already generates this expression. | |||||||||
775 | if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Mul->getOperand(1))) { | |||||||||
776 | Value *UVal = U->getValue(); | |||||||||
777 | for (User *UR : UVal->users()) { | |||||||||
778 | // If U is a constant, it may be used by a ConstantExpr. | |||||||||
779 | Instruction *UI = dyn_cast<Instruction>(UR); | |||||||||
780 | if (UI && UI->getOpcode() == Instruction::Mul && | |||||||||
781 | SE.isSCEVable(UI->getType())) { | |||||||||
782 | return SE.getSCEV(UI) == Mul; | |||||||||
783 | } | |||||||||
784 | } | |||||||||
785 | } | |||||||||
786 | } | |||||||||
787 | } | |||||||||
788 | ||||||||||
789 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) { | |||||||||
790 | if (isExistingPhi(AR, SE)) | |||||||||
791 | return false; | |||||||||
792 | } | |||||||||
793 | ||||||||||
794 | // Fow now, consider any other type of expression (div/mul/min/max) high cost. | |||||||||
795 | return true; | |||||||||
796 | } | |||||||||
797 | ||||||||||
798 | /// If any of the instructions is the specified set are trivially dead, delete | |||||||||
799 | /// them and see if this makes any of their operands subsequently dead. | |||||||||
800 | static bool | |||||||||
801 | DeleteTriviallyDeadInstructions(SmallVectorImpl<WeakVH> &DeadInsts) { | |||||||||
802 | bool Changed = false; | |||||||||
803 | ||||||||||
804 | while (!DeadInsts.empty()) { | |||||||||
805 | Value *V = DeadInsts.pop_back_val(); | |||||||||
806 | Instruction *I = dyn_cast_or_null<Instruction>(V); | |||||||||
807 | ||||||||||
808 | if (!I || !isInstructionTriviallyDead(I)) | |||||||||
809 | continue; | |||||||||
810 | ||||||||||
811 | for (Use &O : I->operands()) | |||||||||
812 | if (Instruction *U = dyn_cast<Instruction>(O)) { | |||||||||
813 | O = nullptr; | |||||||||
814 | if (U->use_empty()) | |||||||||
815 | DeadInsts.emplace_back(U); | |||||||||
816 | } | |||||||||
817 | ||||||||||
818 | I->eraseFromParent(); | |||||||||
819 | Changed = true; | |||||||||
820 | } | |||||||||
821 | ||||||||||
822 | return Changed; | |||||||||
823 | } | |||||||||
824 | ||||||||||
825 | namespace { | |||||||||
826 | class LSRUse; | |||||||||
827 | } | |||||||||
828 | ||||||||||
829 | /// \brief Check if the addressing mode defined by \p F is completely | |||||||||
830 | /// folded in \p LU at isel time. | |||||||||
831 | /// This includes address-mode folding and special icmp tricks. | |||||||||
832 | /// This function returns true if \p LU can accommodate what \p F | |||||||||
833 | /// defines and up to 1 base + 1 scaled + offset. | |||||||||
834 | /// In other words, if \p F has several base registers, this function may | |||||||||
835 | /// still return true. Therefore, users still need to account for | |||||||||
836 | /// additional base registers and/or unfolded offsets to derive an | |||||||||
837 | /// accurate cost model. | |||||||||
838 | static bool isAMCompletelyFolded(const TargetTransformInfo &TTI, | |||||||||
839 | const LSRUse &LU, const Formula &F); | |||||||||
840 | // Get the cost of the scaling factor used in F for LU. | |||||||||
841 | static unsigned getScalingFactorCost(const TargetTransformInfo &TTI, | |||||||||
842 | const LSRUse &LU, const Formula &F); | |||||||||
843 | ||||||||||
844 | namespace { | |||||||||
845 | ||||||||||
846 | /// This class is used to measure and compare candidate formulae. | |||||||||
847 | class Cost { | |||||||||
848 | /// TODO: Some of these could be merged. Also, a lexical ordering | |||||||||
849 | /// isn't always optimal. | |||||||||
850 | unsigned NumRegs; | |||||||||
851 | unsigned AddRecCost; | |||||||||
852 | unsigned NumIVMuls; | |||||||||
853 | unsigned NumBaseAdds; | |||||||||
854 | unsigned ImmCost; | |||||||||
855 | unsigned SetupCost; | |||||||||
856 | unsigned ScaleCost; | |||||||||
857 | ||||||||||
858 | public: | |||||||||
859 | Cost() | |||||||||
860 | : NumRegs(0), AddRecCost(0), NumIVMuls(0), NumBaseAdds(0), ImmCost(0), | |||||||||
861 | SetupCost(0), ScaleCost(0) {} | |||||||||
862 | ||||||||||
863 | bool operator<(const Cost &Other) const; | |||||||||
864 | ||||||||||
865 | void Lose(); | |||||||||
866 | ||||||||||
867 | #ifndef NDEBUG | |||||||||
868 | // Once any of the metrics loses, they must all remain losers. | |||||||||
869 | bool isValid() { | |||||||||
870 | return ((NumRegs | AddRecCost | NumIVMuls | NumBaseAdds | |||||||||
871 | | ImmCost | SetupCost | ScaleCost) != ~0u) | |||||||||
872 | || ((NumRegs & AddRecCost & NumIVMuls & NumBaseAdds | |||||||||
873 | & ImmCost & SetupCost & ScaleCost) == ~0u); | |||||||||
874 | } | |||||||||
875 | #endif | |||||||||
876 | ||||||||||
877 | bool isLoser() { | |||||||||
878 | assert(isValid() && "invalid cost")((isValid() && "invalid cost") ? static_cast<void> (0) : __assert_fail ("isValid() && \"invalid cost\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 878, __PRETTY_FUNCTION__)); | |||||||||
879 | return NumRegs == ~0u; | |||||||||
880 | } | |||||||||
881 | ||||||||||
882 | void RateFormula(const TargetTransformInfo &TTI, | |||||||||
883 | const Formula &F, | |||||||||
884 | SmallPtrSetImpl<const SCEV *> &Regs, | |||||||||
885 | const DenseSet<const SCEV *> &VisitedRegs, | |||||||||
886 | const Loop *L, | |||||||||
887 | ScalarEvolution &SE, DominatorTree &DT, | |||||||||
888 | const LSRUse &LU, | |||||||||
889 | SmallPtrSetImpl<const SCEV *> *LoserRegs = nullptr); | |||||||||
890 | ||||||||||
891 | void print(raw_ostream &OS) const; | |||||||||
892 | void dump() const; | |||||||||
893 | ||||||||||
894 | private: | |||||||||
895 | void RateRegister(const SCEV *Reg, | |||||||||
896 | SmallPtrSetImpl<const SCEV *> &Regs, | |||||||||
897 | const Loop *L, | |||||||||
898 | ScalarEvolution &SE, DominatorTree &DT); | |||||||||
899 | void RatePrimaryRegister(const SCEV *Reg, | |||||||||
900 | SmallPtrSetImpl<const SCEV *> &Regs, | |||||||||
901 | const Loop *L, | |||||||||
902 | ScalarEvolution &SE, DominatorTree &DT, | |||||||||
903 | SmallPtrSetImpl<const SCEV *> *LoserRegs); | |||||||||
904 | }; | |||||||||
905 | ||||||||||
906 | /// An operand value in an instruction which is to be replaced with some | |||||||||
907 | /// equivalent, possibly strength-reduced, replacement. | |||||||||
908 | struct LSRFixup { | |||||||||
909 | /// The instruction which will be updated. | |||||||||
910 | Instruction *UserInst; | |||||||||
911 | ||||||||||
912 | /// The operand of the instruction which will be replaced. The operand may be | |||||||||
913 | /// used more than once; every instance will be replaced. | |||||||||
914 | Value *OperandValToReplace; | |||||||||
915 | ||||||||||
916 | /// If this user is to use the post-incremented value of an induction | |||||||||
917 | /// variable, this variable is non-null and holds the loop associated with the | |||||||||
918 | /// induction variable. | |||||||||
919 | PostIncLoopSet PostIncLoops; | |||||||||
920 | ||||||||||
921 | /// A constant offset to be added to the LSRUse expression. This allows | |||||||||
922 | /// multiple fixups to share the same LSRUse with different offsets, for | |||||||||
923 | /// example in an unrolled loop. | |||||||||
924 | int64_t Offset; | |||||||||
925 | ||||||||||
926 | bool isUseFullyOutsideLoop(const Loop *L) const; | |||||||||
927 | ||||||||||
928 | LSRFixup(); | |||||||||
929 | ||||||||||
930 | void print(raw_ostream &OS) const; | |||||||||
931 | void dump() const; | |||||||||
932 | }; | |||||||||
933 | ||||||||||
934 | ||||||||||
935 | /// A DenseMapInfo implementation for holding DenseMaps and DenseSets of sorted | |||||||||
936 | /// SmallVectors of const SCEV*. | |||||||||
937 | struct UniquifierDenseMapInfo { | |||||||||
938 | static SmallVector<const SCEV *, 4> getEmptyKey() { | |||||||||
939 | SmallVector<const SCEV *, 4> V; | |||||||||
940 | V.push_back(reinterpret_cast<const SCEV *>(-1)); | |||||||||
941 | return V; | |||||||||
942 | } | |||||||||
943 | ||||||||||
944 | static SmallVector<const SCEV *, 4> getTombstoneKey() { | |||||||||
945 | SmallVector<const SCEV *, 4> V; | |||||||||
946 | V.push_back(reinterpret_cast<const SCEV *>(-2)); | |||||||||
947 | return V; | |||||||||
948 | } | |||||||||
949 | ||||||||||
950 | static unsigned getHashValue(const SmallVector<const SCEV *, 4> &V) { | |||||||||
951 | return static_cast<unsigned>(hash_combine_range(V.begin(), V.end())); | |||||||||
952 | } | |||||||||
953 | ||||||||||
954 | static bool isEqual(const SmallVector<const SCEV *, 4> &LHS, | |||||||||
955 | const SmallVector<const SCEV *, 4> &RHS) { | |||||||||
956 | return LHS == RHS; | |||||||||
957 | } | |||||||||
958 | }; | |||||||||
959 | ||||||||||
960 | /// This class holds the state that LSR keeps for each use in IVUsers, as well | |||||||||
961 | /// as uses invented by LSR itself. It includes information about what kinds of | |||||||||
962 | /// things can be folded into the user, information about the user itself, and | |||||||||
963 | /// information about how the use may be satisfied. TODO: Represent multiple | |||||||||
964 | /// users of the same expression in common? | |||||||||
965 | class LSRUse { | |||||||||
966 | DenseSet<SmallVector<const SCEV *, 4>, UniquifierDenseMapInfo> Uniquifier; | |||||||||
967 | ||||||||||
968 | public: | |||||||||
969 | /// An enum for a kind of use, indicating what types of scaled and immediate | |||||||||
970 | /// operands it might support. | |||||||||
971 | enum KindType { | |||||||||
972 | Basic, ///< A normal use, with no folding. | |||||||||
973 | Special, ///< A special case of basic, allowing -1 scales. | |||||||||
974 | Address, ///< An address use; folding according to TargetLowering | |||||||||
975 | ICmpZero ///< An equality icmp with both operands folded into one. | |||||||||
976 | // TODO: Add a generic icmp too? | |||||||||
977 | }; | |||||||||
978 | ||||||||||
979 | typedef PointerIntPair<const SCEV *, 2, KindType> SCEVUseKindPair; | |||||||||
980 | ||||||||||
981 | KindType Kind; | |||||||||
982 | MemAccessTy AccessTy; | |||||||||
983 | ||||||||||
984 | /// The list of operands which are to be replaced. | |||||||||
985 | SmallVector<LSRFixup, 8> Fixups; | |||||||||
986 | ||||||||||
987 | /// Keep track of the min and max offsets of the fixups. | |||||||||
988 | int64_t MinOffset; | |||||||||
989 | int64_t MaxOffset; | |||||||||
990 | ||||||||||
991 | /// This records whether all of the fixups using this LSRUse are outside of | |||||||||
992 | /// the loop, in which case some special-case heuristics may be used. | |||||||||
993 | bool AllFixupsOutsideLoop; | |||||||||
994 | ||||||||||
995 | /// RigidFormula is set to true to guarantee that this use will be associated | |||||||||
996 | /// with a single formula--the one that initially matched. Some SCEV | |||||||||
997 | /// expressions cannot be expanded. This allows LSR to consider the registers | |||||||||
998 | /// used by those expressions without the need to expand them later after | |||||||||
999 | /// changing the formula. | |||||||||
1000 | bool RigidFormula; | |||||||||
1001 | ||||||||||
1002 | /// This records the widest use type for any fixup using this | |||||||||
1003 | /// LSRUse. FindUseWithSimilarFormula can't consider uses with different max | |||||||||
1004 | /// fixup widths to be equivalent, because the narrower one may be relying on | |||||||||
1005 | /// the implicit truncation to truncate away bogus bits. | |||||||||
1006 | Type *WidestFixupType; | |||||||||
1007 | ||||||||||
1008 | /// A list of ways to build a value that can satisfy this user. After the | |||||||||
1009 | /// list is populated, one of these is selected heuristically and used to | |||||||||
1010 | /// formulate a replacement for OperandValToReplace in UserInst. | |||||||||
1011 | SmallVector<Formula, 12> Formulae; | |||||||||
1012 | ||||||||||
1013 | /// The set of register candidates used by all formulae in this LSRUse. | |||||||||
1014 | SmallPtrSet<const SCEV *, 4> Regs; | |||||||||
1015 | ||||||||||
1016 | LSRUse(KindType K, MemAccessTy AT) | |||||||||
1017 | : Kind(K), AccessTy(AT), MinOffset(INT64_MAX(9223372036854775807L)), MaxOffset(INT64_MIN(-9223372036854775807L -1)), | |||||||||
1018 | AllFixupsOutsideLoop(true), RigidFormula(false), | |||||||||
1019 | WidestFixupType(nullptr) {} | |||||||||
1020 | ||||||||||
1021 | LSRFixup &getNewFixup() { | |||||||||
1022 | Fixups.push_back(LSRFixup()); | |||||||||
1023 | return Fixups.back(); | |||||||||
1024 | } | |||||||||
1025 | ||||||||||
1026 | void pushFixup(LSRFixup &f) { | |||||||||
1027 | Fixups.push_back(f); | |||||||||
1028 | if (f.Offset > MaxOffset) | |||||||||
1029 | MaxOffset = f.Offset; | |||||||||
1030 | if (f.Offset < MinOffset) | |||||||||
1031 | MinOffset = f.Offset; | |||||||||
1032 | } | |||||||||
1033 | ||||||||||
1034 | bool HasFormulaWithSameRegs(const Formula &F) const; | |||||||||
1035 | bool InsertFormula(const Formula &F); | |||||||||
1036 | void DeleteFormula(Formula &F); | |||||||||
1037 | void RecomputeRegs(size_t LUIdx, RegUseTracker &Reguses); | |||||||||
1038 | ||||||||||
1039 | void print(raw_ostream &OS) const; | |||||||||
1040 | void dump() const; | |||||||||
1041 | }; | |||||||||
1042 | ||||||||||
1043 | } | |||||||||
1044 | ||||||||||
1045 | /// Tally up interesting quantities from the given register. | |||||||||
1046 | void Cost::RateRegister(const SCEV *Reg, | |||||||||
1047 | SmallPtrSetImpl<const SCEV *> &Regs, | |||||||||
1048 | const Loop *L, | |||||||||
1049 | ScalarEvolution &SE, DominatorTree &DT) { | |||||||||
1050 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Reg)) { | |||||||||
1051 | // If this is an addrec for another loop, don't second-guess its addrec phi | |||||||||
1052 | // nodes. LSR isn't currently smart enough to reason about more than one | |||||||||
1053 | // loop at a time. LSR has already run on inner loops, will not run on outer | |||||||||
1054 | // loops, and cannot be expected to change sibling loops. | |||||||||
1055 | if (AR->getLoop() != L) { | |||||||||
1056 | // If the AddRec exists, consider it's register free and leave it alone. | |||||||||
1057 | if (isExistingPhi(AR, SE)) | |||||||||
1058 | return; | |||||||||
1059 | ||||||||||
1060 | // Otherwise, do not consider this formula at all. | |||||||||
1061 | Lose(); | |||||||||
1062 | return; | |||||||||
1063 | } | |||||||||
1064 | AddRecCost += 1; /// TODO: This should be a function of the stride. | |||||||||
1065 | ||||||||||
1066 | // Add the step value register, if it needs one. | |||||||||
1067 | // TODO: The non-affine case isn't precisely modeled here. | |||||||||
1068 | if (!AR->isAffine() || !isa<SCEVConstant>(AR->getOperand(1))) { | |||||||||
1069 | if (!Regs.count(AR->getOperand(1))) { | |||||||||
1070 | RateRegister(AR->getOperand(1), Regs, L, SE, DT); | |||||||||
1071 | if (isLoser()) | |||||||||
1072 | return; | |||||||||
1073 | } | |||||||||
1074 | } | |||||||||
1075 | } | |||||||||
1076 | ++NumRegs; | |||||||||
1077 | ||||||||||
1078 | // Rough heuristic; favor registers which don't require extra setup | |||||||||
1079 | // instructions in the preheader. | |||||||||
1080 | if (!isa<SCEVUnknown>(Reg) && | |||||||||
1081 | !isa<SCEVConstant>(Reg) && | |||||||||
1082 | !(isa<SCEVAddRecExpr>(Reg) && | |||||||||
1083 | (isa<SCEVUnknown>(cast<SCEVAddRecExpr>(Reg)->getStart()) || | |||||||||
1084 | isa<SCEVConstant>(cast<SCEVAddRecExpr>(Reg)->getStart())))) | |||||||||
1085 | ++SetupCost; | |||||||||
1086 | ||||||||||
1087 | NumIVMuls += isa<SCEVMulExpr>(Reg) && | |||||||||
1088 | SE.hasComputableLoopEvolution(Reg, L); | |||||||||
1089 | } | |||||||||
1090 | ||||||||||
1091 | /// Record this register in the set. If we haven't seen it before, rate | |||||||||
1092 | /// it. Optional LoserRegs provides a way to declare any formula that refers to | |||||||||
1093 | /// one of those regs an instant loser. | |||||||||
1094 | void Cost::RatePrimaryRegister(const SCEV *Reg, | |||||||||
1095 | SmallPtrSetImpl<const SCEV *> &Regs, | |||||||||
1096 | const Loop *L, | |||||||||
1097 | ScalarEvolution &SE, DominatorTree &DT, | |||||||||
1098 | SmallPtrSetImpl<const SCEV *> *LoserRegs) { | |||||||||
1099 | if (LoserRegs && LoserRegs->count(Reg)) { | |||||||||
1100 | Lose(); | |||||||||
1101 | return; | |||||||||
1102 | } | |||||||||
1103 | if (Regs.insert(Reg).second) { | |||||||||
1104 | RateRegister(Reg, Regs, L, SE, DT); | |||||||||
1105 | if (LoserRegs && isLoser()) | |||||||||
1106 | LoserRegs->insert(Reg); | |||||||||
1107 | } | |||||||||
1108 | } | |||||||||
1109 | ||||||||||
1110 | void Cost::RateFormula(const TargetTransformInfo &TTI, | |||||||||
1111 | const Formula &F, | |||||||||
1112 | SmallPtrSetImpl<const SCEV *> &Regs, | |||||||||
1113 | const DenseSet<const SCEV *> &VisitedRegs, | |||||||||
1114 | const Loop *L, | |||||||||
1115 | ScalarEvolution &SE, DominatorTree &DT, | |||||||||
1116 | const LSRUse &LU, | |||||||||
1117 | SmallPtrSetImpl<const SCEV *> *LoserRegs) { | |||||||||
1118 | assert(F.isCanonical() && "Cost is accurate only for canonical formula")((F.isCanonical() && "Cost is accurate only for canonical formula" ) ? static_cast<void> (0) : __assert_fail ("F.isCanonical() && \"Cost is accurate only for canonical formula\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1118, __PRETTY_FUNCTION__)); | |||||||||
1119 | // Tally up the registers. | |||||||||
1120 | if (const SCEV *ScaledReg = F.ScaledReg) { | |||||||||
1121 | if (VisitedRegs.count(ScaledReg)) { | |||||||||
1122 | Lose(); | |||||||||
1123 | return; | |||||||||
1124 | } | |||||||||
1125 | RatePrimaryRegister(ScaledReg, Regs, L, SE, DT, LoserRegs); | |||||||||
1126 | if (isLoser()) | |||||||||
1127 | return; | |||||||||
1128 | } | |||||||||
1129 | for (const SCEV *BaseReg : F.BaseRegs) { | |||||||||
1130 | if (VisitedRegs.count(BaseReg)) { | |||||||||
1131 | Lose(); | |||||||||
1132 | return; | |||||||||
1133 | } | |||||||||
1134 | RatePrimaryRegister(BaseReg, Regs, L, SE, DT, LoserRegs); | |||||||||
1135 | if (isLoser()) | |||||||||
1136 | return; | |||||||||
1137 | } | |||||||||
1138 | ||||||||||
1139 | // Determine how many (unfolded) adds we'll need inside the loop. | |||||||||
1140 | size_t NumBaseParts = F.getNumRegs(); | |||||||||
1141 | if (NumBaseParts > 1) | |||||||||
1142 | // Do not count the base and a possible second register if the target | |||||||||
1143 | // allows to fold 2 registers. | |||||||||
1144 | NumBaseAdds += | |||||||||
1145 | NumBaseParts - (1 + (F.Scale && isAMCompletelyFolded(TTI, LU, F))); | |||||||||
1146 | NumBaseAdds += (F.UnfoldedOffset != 0); | |||||||||
1147 | ||||||||||
1148 | // Accumulate non-free scaling amounts. | |||||||||
1149 | ScaleCost += getScalingFactorCost(TTI, LU, F); | |||||||||
1150 | ||||||||||
1151 | // Tally up the non-zero immediates. | |||||||||
1152 | for (const LSRFixup &Fixup : LU.Fixups) { | |||||||||
1153 | int64_t O = Fixup.Offset; | |||||||||
1154 | int64_t Offset = (uint64_t)O + F.BaseOffset; | |||||||||
1155 | if (F.BaseGV) | |||||||||
1156 | ImmCost += 64; // Handle symbolic values conservatively. | |||||||||
1157 | // TODO: This should probably be the pointer size. | |||||||||
1158 | else if (Offset != 0) | |||||||||
1159 | ImmCost += APInt(64, Offset, true).getMinSignedBits(); | |||||||||
1160 | ||||||||||
1161 | // Check with target if this offset with this instruction is | |||||||||
1162 | // specifically not supported. | |||||||||
1163 | if ((isa<LoadInst>(Fixup.UserInst) || isa<StoreInst>(Fixup.UserInst)) && | |||||||||
1164 | !TTI.isFoldableMemAccessOffset(Fixup.UserInst, Offset)) | |||||||||
1165 | NumBaseAdds++; | |||||||||
1166 | } | |||||||||
1167 | assert(isValid() && "invalid cost")((isValid() && "invalid cost") ? static_cast<void> (0) : __assert_fail ("isValid() && \"invalid cost\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1167, __PRETTY_FUNCTION__)); | |||||||||
1168 | } | |||||||||
1169 | ||||||||||
1170 | /// Set this cost to a losing value. | |||||||||
1171 | void Cost::Lose() { | |||||||||
1172 | NumRegs = ~0u; | |||||||||
1173 | AddRecCost = ~0u; | |||||||||
1174 | NumIVMuls = ~0u; | |||||||||
1175 | NumBaseAdds = ~0u; | |||||||||
1176 | ImmCost = ~0u; | |||||||||
1177 | SetupCost = ~0u; | |||||||||
1178 | ScaleCost = ~0u; | |||||||||
1179 | } | |||||||||
1180 | ||||||||||
1181 | /// Choose the lower cost. | |||||||||
1182 | bool Cost::operator<(const Cost &Other) const { | |||||||||
1183 | return std::tie(NumRegs, AddRecCost, NumIVMuls, NumBaseAdds, ScaleCost, | |||||||||
1184 | ImmCost, SetupCost) < | |||||||||
1185 | std::tie(Other.NumRegs, Other.AddRecCost, Other.NumIVMuls, | |||||||||
1186 | Other.NumBaseAdds, Other.ScaleCost, Other.ImmCost, | |||||||||
1187 | Other.SetupCost); | |||||||||
1188 | } | |||||||||
1189 | ||||||||||
1190 | void Cost::print(raw_ostream &OS) const { | |||||||||
1191 | OS << NumRegs << " reg" << (NumRegs == 1 ? "" : "s"); | |||||||||
1192 | if (AddRecCost != 0) | |||||||||
1193 | OS << ", with addrec cost " << AddRecCost; | |||||||||
1194 | if (NumIVMuls != 0) | |||||||||
1195 | OS << ", plus " << NumIVMuls << " IV mul" << (NumIVMuls == 1 ? "" : "s"); | |||||||||
1196 | if (NumBaseAdds != 0) | |||||||||
1197 | OS << ", plus " << NumBaseAdds << " base add" | |||||||||
1198 | << (NumBaseAdds == 1 ? "" : "s"); | |||||||||
1199 | if (ScaleCost != 0) | |||||||||
1200 | OS << ", plus " << ScaleCost << " scale cost"; | |||||||||
1201 | if (ImmCost != 0) | |||||||||
1202 | OS << ", plus " << ImmCost << " imm cost"; | |||||||||
1203 | if (SetupCost != 0) | |||||||||
1204 | OS << ", plus " << SetupCost << " setup cost"; | |||||||||
1205 | } | |||||||||
1206 | ||||||||||
1207 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) | |||||||||
1208 | void Cost::dump() const { | |||||||||
1209 | print(errs()); errs() << '\n'; | |||||||||
1210 | } | |||||||||
1211 | ||||||||||
1212 | LSRFixup::LSRFixup() | |||||||||
1213 | : UserInst(nullptr), OperandValToReplace(nullptr), | |||||||||
1214 | Offset(0) {} | |||||||||
1215 | ||||||||||
1216 | /// Test whether this fixup always uses its value outside of the given loop. | |||||||||
1217 | bool LSRFixup::isUseFullyOutsideLoop(const Loop *L) const { | |||||||||
1218 | // PHI nodes use their value in their incoming blocks. | |||||||||
1219 | if (const PHINode *PN = dyn_cast<PHINode>(UserInst)) { | |||||||||
1220 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) | |||||||||
1221 | if (PN->getIncomingValue(i) == OperandValToReplace && | |||||||||
1222 | L->contains(PN->getIncomingBlock(i))) | |||||||||
1223 | return false; | |||||||||
1224 | return true; | |||||||||
1225 | } | |||||||||
1226 | ||||||||||
1227 | return !L->contains(UserInst); | |||||||||
1228 | } | |||||||||
1229 | ||||||||||
1230 | void LSRFixup::print(raw_ostream &OS) const { | |||||||||
1231 | OS << "UserInst="; | |||||||||
1232 | // Store is common and interesting enough to be worth special-casing. | |||||||||
1233 | if (StoreInst *Store = dyn_cast<StoreInst>(UserInst)) { | |||||||||
1234 | OS << "store "; | |||||||||
1235 | Store->getOperand(0)->printAsOperand(OS, /*PrintType=*/false); | |||||||||
1236 | } else if (UserInst->getType()->isVoidTy()) | |||||||||
1237 | OS << UserInst->getOpcodeName(); | |||||||||
1238 | else | |||||||||
1239 | UserInst->printAsOperand(OS, /*PrintType=*/false); | |||||||||
1240 | ||||||||||
1241 | OS << ", OperandValToReplace="; | |||||||||
1242 | OperandValToReplace->printAsOperand(OS, /*PrintType=*/false); | |||||||||
1243 | ||||||||||
1244 | for (const Loop *PIL : PostIncLoops) { | |||||||||
1245 | OS << ", PostIncLoop="; | |||||||||
1246 | PIL->getHeader()->printAsOperand(OS, /*PrintType=*/false); | |||||||||
1247 | } | |||||||||
1248 | ||||||||||
1249 | if (Offset != 0) | |||||||||
1250 | OS << ", Offset=" << Offset; | |||||||||
1251 | } | |||||||||
1252 | ||||||||||
1253 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) | |||||||||
1254 | void LSRFixup::dump() const { | |||||||||
1255 | print(errs()); errs() << '\n'; | |||||||||
1256 | } | |||||||||
1257 | ||||||||||
1258 | /// Test whether this use as a formula which has the same registers as the given | |||||||||
1259 | /// formula. | |||||||||
1260 | bool LSRUse::HasFormulaWithSameRegs(const Formula &F) const { | |||||||||
1261 | SmallVector<const SCEV *, 4> Key = F.BaseRegs; | |||||||||
1262 | if (F.ScaledReg) Key.push_back(F.ScaledReg); | |||||||||
1263 | // Unstable sort by host order ok, because this is only used for uniquifying. | |||||||||
1264 | std::sort(Key.begin(), Key.end()); | |||||||||
1265 | return Uniquifier.count(Key); | |||||||||
1266 | } | |||||||||
1267 | ||||||||||
1268 | /// If the given formula has not yet been inserted, add it to the list, and | |||||||||
1269 | /// return true. Return false otherwise. The formula must be in canonical form. | |||||||||
1270 | bool LSRUse::InsertFormula(const Formula &F) { | |||||||||
1271 | assert(F.isCanonical() && "Invalid canonical representation")((F.isCanonical() && "Invalid canonical representation" ) ? static_cast<void> (0) : __assert_fail ("F.isCanonical() && \"Invalid canonical representation\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1271, __PRETTY_FUNCTION__)); | |||||||||
1272 | ||||||||||
1273 | if (!Formulae.empty() && RigidFormula) | |||||||||
1274 | return false; | |||||||||
1275 | ||||||||||
1276 | SmallVector<const SCEV *, 4> Key = F.BaseRegs; | |||||||||
1277 | if (F.ScaledReg) Key.push_back(F.ScaledReg); | |||||||||
1278 | // Unstable sort by host order ok, because this is only used for uniquifying. | |||||||||
1279 | std::sort(Key.begin(), Key.end()); | |||||||||
1280 | ||||||||||
1281 | if (!Uniquifier.insert(Key).second) | |||||||||
1282 | return false; | |||||||||
1283 | ||||||||||
1284 | // Using a register to hold the value of 0 is not profitable. | |||||||||
1285 | assert((!F.ScaledReg || !F.ScaledReg->isZero()) &&(((!F.ScaledReg || !F.ScaledReg->isZero()) && "Zero allocated in a scaled register!" ) ? static_cast<void> (0) : __assert_fail ("(!F.ScaledReg || !F.ScaledReg->isZero()) && \"Zero allocated in a scaled register!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1286, __PRETTY_FUNCTION__)) | |||||||||
1286 | "Zero allocated in a scaled register!")(((!F.ScaledReg || !F.ScaledReg->isZero()) && "Zero allocated in a scaled register!" ) ? static_cast<void> (0) : __assert_fail ("(!F.ScaledReg || !F.ScaledReg->isZero()) && \"Zero allocated in a scaled register!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1286, __PRETTY_FUNCTION__)); | |||||||||
1287 | #ifndef NDEBUG | |||||||||
1288 | for (const SCEV *BaseReg : F.BaseRegs) | |||||||||
1289 | assert(!BaseReg->isZero() && "Zero allocated in a base register!")((!BaseReg->isZero() && "Zero allocated in a base register!" ) ? static_cast<void> (0) : __assert_fail ("!BaseReg->isZero() && \"Zero allocated in a base register!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1289, __PRETTY_FUNCTION__)); | |||||||||
1290 | #endif | |||||||||
1291 | ||||||||||
1292 | // Add the formula to the list. | |||||||||
1293 | Formulae.push_back(F); | |||||||||
1294 | ||||||||||
1295 | // Record registers now being used by this use. | |||||||||
1296 | Regs.insert(F.BaseRegs.begin(), F.BaseRegs.end()); | |||||||||
1297 | if (F.ScaledReg) | |||||||||
1298 | Regs.insert(F.ScaledReg); | |||||||||
1299 | ||||||||||
1300 | return true; | |||||||||
1301 | } | |||||||||
1302 | ||||||||||
1303 | /// Remove the given formula from this use's list. | |||||||||
1304 | void LSRUse::DeleteFormula(Formula &F) { | |||||||||
1305 | if (&F != &Formulae.back()) | |||||||||
1306 | std::swap(F, Formulae.back()); | |||||||||
1307 | Formulae.pop_back(); | |||||||||
1308 | } | |||||||||
1309 | ||||||||||
1310 | /// Recompute the Regs field, and update RegUses. | |||||||||
1311 | void LSRUse::RecomputeRegs(size_t LUIdx, RegUseTracker &RegUses) { | |||||||||
1312 | // Now that we've filtered out some formulae, recompute the Regs set. | |||||||||
1313 | SmallPtrSet<const SCEV *, 4> OldRegs = std::move(Regs); | |||||||||
1314 | Regs.clear(); | |||||||||
1315 | for (const Formula &F : Formulae) { | |||||||||
1316 | if (F.ScaledReg) Regs.insert(F.ScaledReg); | |||||||||
1317 | Regs.insert(F.BaseRegs.begin(), F.BaseRegs.end()); | |||||||||
1318 | } | |||||||||
1319 | ||||||||||
1320 | // Update the RegTracker. | |||||||||
1321 | for (const SCEV *S : OldRegs) | |||||||||
1322 | if (!Regs.count(S)) | |||||||||
1323 | RegUses.dropRegister(S, LUIdx); | |||||||||
1324 | } | |||||||||
1325 | ||||||||||
1326 | void LSRUse::print(raw_ostream &OS) const { | |||||||||
1327 | OS << "LSR Use: Kind="; | |||||||||
1328 | switch (Kind) { | |||||||||
1329 | case Basic: OS << "Basic"; break; | |||||||||
1330 | case Special: OS << "Special"; break; | |||||||||
1331 | case ICmpZero: OS << "ICmpZero"; break; | |||||||||
1332 | case Address: | |||||||||
1333 | OS << "Address of "; | |||||||||
1334 | if (AccessTy.MemTy->isPointerTy()) | |||||||||
1335 | OS << "pointer"; // the full pointer type could be really verbose | |||||||||
1336 | else { | |||||||||
1337 | OS << *AccessTy.MemTy; | |||||||||
1338 | } | |||||||||
1339 | ||||||||||
1340 | OS << " in addrspace(" << AccessTy.AddrSpace << ')'; | |||||||||
1341 | } | |||||||||
1342 | ||||||||||
1343 | OS << ", Offsets={"; | |||||||||
1344 | bool NeedComma = false; | |||||||||
1345 | for (const LSRFixup &Fixup : Fixups) { | |||||||||
1346 | if (NeedComma) OS << ','; | |||||||||
1347 | OS << Fixup.Offset; | |||||||||
1348 | NeedComma = true; | |||||||||
1349 | } | |||||||||
1350 | OS << '}'; | |||||||||
1351 | ||||||||||
1352 | if (AllFixupsOutsideLoop) | |||||||||
1353 | OS << ", all-fixups-outside-loop"; | |||||||||
1354 | ||||||||||
1355 | if (WidestFixupType) | |||||||||
1356 | OS << ", widest fixup type: " << *WidestFixupType; | |||||||||
1357 | } | |||||||||
1358 | ||||||||||
1359 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) | |||||||||
1360 | void LSRUse::dump() const { | |||||||||
1361 | print(errs()); errs() << '\n'; | |||||||||
1362 | } | |||||||||
1363 | ||||||||||
1364 | static bool isAMCompletelyFolded(const TargetTransformInfo &TTI, | |||||||||
1365 | LSRUse::KindType Kind, MemAccessTy AccessTy, | |||||||||
1366 | GlobalValue *BaseGV, int64_t BaseOffset, | |||||||||
1367 | bool HasBaseReg, int64_t Scale) { | |||||||||
1368 | switch (Kind) { | |||||||||
1369 | case LSRUse::Address: | |||||||||
1370 | return TTI.isLegalAddressingMode(AccessTy.MemTy, BaseGV, BaseOffset, | |||||||||
1371 | HasBaseReg, Scale, AccessTy.AddrSpace); | |||||||||
1372 | ||||||||||
1373 | case LSRUse::ICmpZero: | |||||||||
1374 | // There's not even a target hook for querying whether it would be legal to | |||||||||
1375 | // fold a GV into an ICmp. | |||||||||
1376 | if (BaseGV) | |||||||||
1377 | return false; | |||||||||
1378 | ||||||||||
1379 | // ICmp only has two operands; don't allow more than two non-trivial parts. | |||||||||
1380 | if (Scale != 0 && HasBaseReg && BaseOffset != 0) | |||||||||
1381 | return false; | |||||||||
1382 | ||||||||||
1383 | // ICmp only supports no scale or a -1 scale, as we can "fold" a -1 scale by | |||||||||
1384 | // putting the scaled register in the other operand of the icmp. | |||||||||
1385 | if (Scale != 0 && Scale != -1) | |||||||||
1386 | return false; | |||||||||
1387 | ||||||||||
1388 | // If we have low-level target information, ask the target if it can fold an | |||||||||
1389 | // integer immediate on an icmp. | |||||||||
1390 | if (BaseOffset != 0) { | |||||||||
1391 | // We have one of: | |||||||||
1392 | // ICmpZero BaseReg + BaseOffset => ICmp BaseReg, -BaseOffset | |||||||||
1393 | // ICmpZero -1*ScaleReg + BaseOffset => ICmp ScaleReg, BaseOffset | |||||||||
1394 | // Offs is the ICmp immediate. | |||||||||
1395 | if (Scale == 0) | |||||||||
1396 | // The cast does the right thing with INT64_MIN. | |||||||||
1397 | BaseOffset = -(uint64_t)BaseOffset; | |||||||||
1398 | return TTI.isLegalICmpImmediate(BaseOffset); | |||||||||
1399 | } | |||||||||
1400 | ||||||||||
1401 | // ICmpZero BaseReg + -1*ScaleReg => ICmp BaseReg, ScaleReg | |||||||||
1402 | return true; | |||||||||
1403 | ||||||||||
1404 | case LSRUse::Basic: | |||||||||
1405 | // Only handle single-register values. | |||||||||
1406 | return !BaseGV && Scale == 0 && BaseOffset == 0; | |||||||||
1407 | ||||||||||
1408 | case LSRUse::Special: | |||||||||
1409 | // Special case Basic to handle -1 scales. | |||||||||
1410 | return !BaseGV && (Scale == 0 || Scale == -1) && BaseOffset == 0; | |||||||||
1411 | } | |||||||||
1412 | ||||||||||
1413 | llvm_unreachable("Invalid LSRUse Kind!")::llvm::llvm_unreachable_internal("Invalid LSRUse Kind!", "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1413); | |||||||||
1414 | } | |||||||||
1415 | ||||||||||
1416 | static bool isAMCompletelyFolded(const TargetTransformInfo &TTI, | |||||||||
1417 | int64_t MinOffset, int64_t MaxOffset, | |||||||||
1418 | LSRUse::KindType Kind, MemAccessTy AccessTy, | |||||||||
1419 | GlobalValue *BaseGV, int64_t BaseOffset, | |||||||||
1420 | bool HasBaseReg, int64_t Scale) { | |||||||||
1421 | // Check for overflow. | |||||||||
1422 | if (((int64_t)((uint64_t)BaseOffset + MinOffset) > BaseOffset) != | |||||||||
1423 | (MinOffset > 0)) | |||||||||
1424 | return false; | |||||||||
1425 | MinOffset = (uint64_t)BaseOffset + MinOffset; | |||||||||
1426 | if (((int64_t)((uint64_t)BaseOffset + MaxOffset) > BaseOffset) != | |||||||||
1427 | (MaxOffset > 0)) | |||||||||
1428 | return false; | |||||||||
1429 | MaxOffset = (uint64_t)BaseOffset + MaxOffset; | |||||||||
1430 | ||||||||||
1431 | return isAMCompletelyFolded(TTI, Kind, AccessTy, BaseGV, MinOffset, | |||||||||
1432 | HasBaseReg, Scale) && | |||||||||
1433 | isAMCompletelyFolded(TTI, Kind, AccessTy, BaseGV, MaxOffset, | |||||||||
1434 | HasBaseReg, Scale); | |||||||||
1435 | } | |||||||||
1436 | ||||||||||
1437 | static bool isAMCompletelyFolded(const TargetTransformInfo &TTI, | |||||||||
1438 | int64_t MinOffset, int64_t MaxOffset, | |||||||||
1439 | LSRUse::KindType Kind, MemAccessTy AccessTy, | |||||||||
1440 | const Formula &F) { | |||||||||
1441 | // For the purpose of isAMCompletelyFolded either having a canonical formula | |||||||||
1442 | // or a scale not equal to zero is correct. | |||||||||
1443 | // Problems may arise from non canonical formulae having a scale == 0. | |||||||||
1444 | // Strictly speaking it would best to just rely on canonical formulae. | |||||||||
1445 | // However, when we generate the scaled formulae, we first check that the | |||||||||
1446 | // scaling factor is profitable before computing the actual ScaledReg for | |||||||||
1447 | // compile time sake. | |||||||||
1448 | assert((F.isCanonical() || F.Scale != 0))(((F.isCanonical() || F.Scale != 0)) ? static_cast<void> (0) : __assert_fail ("(F.isCanonical() || F.Scale != 0)", "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1448, __PRETTY_FUNCTION__)); | |||||||||
1449 | return isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy, | |||||||||
1450 | F.BaseGV, F.BaseOffset, F.HasBaseReg, F.Scale); | |||||||||
1451 | } | |||||||||
1452 | ||||||||||
1453 | /// Test whether we know how to expand the current formula. | |||||||||
1454 | static bool isLegalUse(const TargetTransformInfo &TTI, int64_t MinOffset, | |||||||||
1455 | int64_t MaxOffset, LSRUse::KindType Kind, | |||||||||
1456 | MemAccessTy AccessTy, GlobalValue *BaseGV, | |||||||||
1457 | int64_t BaseOffset, bool HasBaseReg, int64_t Scale) { | |||||||||
1458 | // We know how to expand completely foldable formulae. | |||||||||
1459 | return isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy, BaseGV, | |||||||||
1460 | BaseOffset, HasBaseReg, Scale) || | |||||||||
1461 | // Or formulae that use a base register produced by a sum of base | |||||||||
1462 | // registers. | |||||||||
1463 | (Scale == 1 && | |||||||||
1464 | isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy, | |||||||||
1465 | BaseGV, BaseOffset, true, 0)); | |||||||||
1466 | } | |||||||||
1467 | ||||||||||
1468 | static bool isLegalUse(const TargetTransformInfo &TTI, int64_t MinOffset, | |||||||||
1469 | int64_t MaxOffset, LSRUse::KindType Kind, | |||||||||
1470 | MemAccessTy AccessTy, const Formula &F) { | |||||||||
1471 | return isLegalUse(TTI, MinOffset, MaxOffset, Kind, AccessTy, F.BaseGV, | |||||||||
1472 | F.BaseOffset, F.HasBaseReg, F.Scale); | |||||||||
1473 | } | |||||||||
1474 | ||||||||||
1475 | static bool isAMCompletelyFolded(const TargetTransformInfo &TTI, | |||||||||
1476 | const LSRUse &LU, const Formula &F) { | |||||||||
1477 | return isAMCompletelyFolded(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, | |||||||||
1478 | LU.AccessTy, F.BaseGV, F.BaseOffset, F.HasBaseReg, | |||||||||
1479 | F.Scale); | |||||||||
1480 | } | |||||||||
1481 | ||||||||||
1482 | static unsigned getScalingFactorCost(const TargetTransformInfo &TTI, | |||||||||
1483 | const LSRUse &LU, const Formula &F) { | |||||||||
1484 | if (!F.Scale) | |||||||||
1485 | return 0; | |||||||||
1486 | ||||||||||
1487 | // If the use is not completely folded in that instruction, we will have to | |||||||||
1488 | // pay an extra cost only for scale != 1. | |||||||||
1489 | if (!isAMCompletelyFolded(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, | |||||||||
1490 | LU.AccessTy, F)) | |||||||||
1491 | return F.Scale != 1; | |||||||||
1492 | ||||||||||
1493 | switch (LU.Kind) { | |||||||||
1494 | case LSRUse::Address: { | |||||||||
1495 | // Check the scaling factor cost with both the min and max offsets. | |||||||||
1496 | int ScaleCostMinOffset = TTI.getScalingFactorCost( | |||||||||
1497 | LU.AccessTy.MemTy, F.BaseGV, F.BaseOffset + LU.MinOffset, F.HasBaseReg, | |||||||||
1498 | F.Scale, LU.AccessTy.AddrSpace); | |||||||||
1499 | int ScaleCostMaxOffset = TTI.getScalingFactorCost( | |||||||||
1500 | LU.AccessTy.MemTy, F.BaseGV, F.BaseOffset + LU.MaxOffset, F.HasBaseReg, | |||||||||
1501 | F.Scale, LU.AccessTy.AddrSpace); | |||||||||
1502 | ||||||||||
1503 | assert(ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >= 0 &&((ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >= 0 && "Legal addressing mode has an illegal cost!") ? static_cast<void> (0) : __assert_fail ("ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >= 0 && \"Legal addressing mode has an illegal cost!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1504, __PRETTY_FUNCTION__)) | |||||||||
1504 | "Legal addressing mode has an illegal cost!")((ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >= 0 && "Legal addressing mode has an illegal cost!") ? static_cast<void> (0) : __assert_fail ("ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >= 0 && \"Legal addressing mode has an illegal cost!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1504, __PRETTY_FUNCTION__)); | |||||||||
1505 | return std::max(ScaleCostMinOffset, ScaleCostMaxOffset); | |||||||||
1506 | } | |||||||||
1507 | case LSRUse::ICmpZero: | |||||||||
1508 | case LSRUse::Basic: | |||||||||
1509 | case LSRUse::Special: | |||||||||
1510 | // The use is completely folded, i.e., everything is folded into the | |||||||||
1511 | // instruction. | |||||||||
1512 | return 0; | |||||||||
1513 | } | |||||||||
1514 | ||||||||||
1515 | llvm_unreachable("Invalid LSRUse Kind!")::llvm::llvm_unreachable_internal("Invalid LSRUse Kind!", "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1515); | |||||||||
1516 | } | |||||||||
1517 | ||||||||||
1518 | static bool isAlwaysFoldable(const TargetTransformInfo &TTI, | |||||||||
1519 | LSRUse::KindType Kind, MemAccessTy AccessTy, | |||||||||
1520 | GlobalValue *BaseGV, int64_t BaseOffset, | |||||||||
1521 | bool HasBaseReg) { | |||||||||
1522 | // Fast-path: zero is always foldable. | |||||||||
1523 | if (BaseOffset == 0 && !BaseGV) return true; | |||||||||
1524 | ||||||||||
1525 | // Conservatively, create an address with an immediate and a | |||||||||
1526 | // base and a scale. | |||||||||
1527 | int64_t Scale = Kind == LSRUse::ICmpZero ? -1 : 1; | |||||||||
1528 | ||||||||||
1529 | // Canonicalize a scale of 1 to a base register if the formula doesn't | |||||||||
1530 | // already have a base register. | |||||||||
1531 | if (!HasBaseReg && Scale == 1) { | |||||||||
1532 | Scale = 0; | |||||||||
1533 | HasBaseReg = true; | |||||||||
1534 | } | |||||||||
1535 | ||||||||||
1536 | return isAMCompletelyFolded(TTI, Kind, AccessTy, BaseGV, BaseOffset, | |||||||||
1537 | HasBaseReg, Scale); | |||||||||
1538 | } | |||||||||
1539 | ||||||||||
1540 | static bool isAlwaysFoldable(const TargetTransformInfo &TTI, | |||||||||
1541 | ScalarEvolution &SE, int64_t MinOffset, | |||||||||
1542 | int64_t MaxOffset, LSRUse::KindType Kind, | |||||||||
1543 | MemAccessTy AccessTy, const SCEV *S, | |||||||||
1544 | bool HasBaseReg) { | |||||||||
1545 | // Fast-path: zero is always foldable. | |||||||||
1546 | if (S->isZero()) return true; | |||||||||
1547 | ||||||||||
1548 | // Conservatively, create an address with an immediate and a | |||||||||
1549 | // base and a scale. | |||||||||
1550 | int64_t BaseOffset = ExtractImmediate(S, SE); | |||||||||
1551 | GlobalValue *BaseGV = ExtractSymbol(S, SE); | |||||||||
1552 | ||||||||||
1553 | // If there's anything else involved, it's not foldable. | |||||||||
1554 | if (!S->isZero()) return false; | |||||||||
1555 | ||||||||||
1556 | // Fast-path: zero is always foldable. | |||||||||
1557 | if (BaseOffset == 0 && !BaseGV) return true; | |||||||||
1558 | ||||||||||
1559 | // Conservatively, create an address with an immediate and a | |||||||||
1560 | // base and a scale. | |||||||||
1561 | int64_t Scale = Kind == LSRUse::ICmpZero ? -1 : 1; | |||||||||
1562 | ||||||||||
1563 | return isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy, BaseGV, | |||||||||
1564 | BaseOffset, HasBaseReg, Scale); | |||||||||
1565 | } | |||||||||
1566 | ||||||||||
1567 | namespace { | |||||||||
1568 | ||||||||||
1569 | /// An individual increment in a Chain of IV increments. Relate an IV user to | |||||||||
1570 | /// an expression that computes the IV it uses from the IV used by the previous | |||||||||
1571 | /// link in the Chain. | |||||||||
1572 | /// | |||||||||
1573 | /// For the head of a chain, IncExpr holds the absolute SCEV expression for the | |||||||||
1574 | /// original IVOperand. The head of the chain's IVOperand is only valid during | |||||||||
1575 | /// chain collection, before LSR replaces IV users. During chain generation, | |||||||||
1576 | /// IncExpr can be used to find the new IVOperand that computes the same | |||||||||
1577 | /// expression. | |||||||||
1578 | struct IVInc { | |||||||||
1579 | Instruction *UserInst; | |||||||||
1580 | Value* IVOperand; | |||||||||
1581 | const SCEV *IncExpr; | |||||||||
1582 | ||||||||||
1583 | IVInc(Instruction *U, Value *O, const SCEV *E): | |||||||||
1584 | UserInst(U), IVOperand(O), IncExpr(E) {} | |||||||||
1585 | }; | |||||||||
1586 | ||||||||||
1587 | // The list of IV increments in program order. We typically add the head of a | |||||||||
1588 | // chain without finding subsequent links. | |||||||||
1589 | struct IVChain { | |||||||||
1590 | SmallVector<IVInc,1> Incs; | |||||||||
1591 | const SCEV *ExprBase; | |||||||||
1592 | ||||||||||
1593 | IVChain() : ExprBase(nullptr) {} | |||||||||
1594 | ||||||||||
1595 | IVChain(const IVInc &Head, const SCEV *Base) | |||||||||
1596 | : Incs(1, Head), ExprBase(Base) {} | |||||||||
1597 | ||||||||||
1598 | typedef SmallVectorImpl<IVInc>::const_iterator const_iterator; | |||||||||
1599 | ||||||||||
1600 | // Return the first increment in the chain. | |||||||||
1601 | const_iterator begin() const { | |||||||||
1602 | assert(!Incs.empty())((!Incs.empty()) ? static_cast<void> (0) : __assert_fail ("!Incs.empty()", "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1602, __PRETTY_FUNCTION__)); | |||||||||
1603 | return std::next(Incs.begin()); | |||||||||
1604 | } | |||||||||
1605 | const_iterator end() const { | |||||||||
1606 | return Incs.end(); | |||||||||
1607 | } | |||||||||
1608 | ||||||||||
1609 | // Returns true if this chain contains any increments. | |||||||||
1610 | bool hasIncs() const { return Incs.size() >= 2; } | |||||||||
1611 | ||||||||||
1612 | // Add an IVInc to the end of this chain. | |||||||||
1613 | void add(const IVInc &X) { Incs.push_back(X); } | |||||||||
1614 | ||||||||||
1615 | // Returns the last UserInst in the chain. | |||||||||
1616 | Instruction *tailUserInst() const { return Incs.back().UserInst; } | |||||||||
1617 | ||||||||||
1618 | // Returns true if IncExpr can be profitably added to this chain. | |||||||||
1619 | bool isProfitableIncrement(const SCEV *OperExpr, | |||||||||
1620 | const SCEV *IncExpr, | |||||||||
1621 | ScalarEvolution&); | |||||||||
1622 | }; | |||||||||
1623 | ||||||||||
1624 | /// Helper for CollectChains to track multiple IV increment uses. Distinguish | |||||||||
1625 | /// between FarUsers that definitely cross IV increments and NearUsers that may | |||||||||
1626 | /// be used between IV increments. | |||||||||
1627 | struct ChainUsers { | |||||||||
1628 | SmallPtrSet<Instruction*, 4> FarUsers; | |||||||||
1629 | SmallPtrSet<Instruction*, 4> NearUsers; | |||||||||
1630 | }; | |||||||||
1631 | ||||||||||
1632 | /// This class holds state for the main loop strength reduction logic. | |||||||||
1633 | class LSRInstance { | |||||||||
1634 | IVUsers &IU; | |||||||||
1635 | ScalarEvolution &SE; | |||||||||
1636 | DominatorTree &DT; | |||||||||
1637 | LoopInfo &LI; | |||||||||
1638 | const TargetTransformInfo &TTI; | |||||||||
1639 | Loop *const L; | |||||||||
1640 | bool Changed; | |||||||||
1641 | ||||||||||
1642 | /// This is the insert position that the current loop's induction variable | |||||||||
1643 | /// increment should be placed. In simple loops, this is the latch block's | |||||||||
1644 | /// terminator. But in more complicated cases, this is a position which will | |||||||||
1645 | /// dominate all the in-loop post-increment users. | |||||||||
1646 | Instruction *IVIncInsertPos; | |||||||||
1647 | ||||||||||
1648 | /// Interesting factors between use strides. | |||||||||
1649 | SmallSetVector<int64_t, 8> Factors; | |||||||||
1650 | ||||||||||
1651 | /// Interesting use types, to facilitate truncation reuse. | |||||||||
1652 | SmallSetVector<Type *, 4> Types; | |||||||||
1653 | ||||||||||
1654 | /// The list of interesting uses. | |||||||||
1655 | SmallVector<LSRUse, 16> Uses; | |||||||||
1656 | ||||||||||
1657 | /// Track which uses use which register candidates. | |||||||||
1658 | RegUseTracker RegUses; | |||||||||
1659 | ||||||||||
1660 | // Limit the number of chains to avoid quadratic behavior. We don't expect to | |||||||||
1661 | // have more than a few IV increment chains in a loop. Missing a Chain falls | |||||||||
1662 | // back to normal LSR behavior for those uses. | |||||||||
1663 | static const unsigned MaxChains = 8; | |||||||||
1664 | ||||||||||
1665 | /// IV users can form a chain of IV increments. | |||||||||
1666 | SmallVector<IVChain, MaxChains> IVChainVec; | |||||||||
1667 | ||||||||||
1668 | /// IV users that belong to profitable IVChains. | |||||||||
1669 | SmallPtrSet<Use*, MaxChains> IVIncSet; | |||||||||
1670 | ||||||||||
1671 | void OptimizeShadowIV(); | |||||||||
1672 | bool FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse); | |||||||||
1673 | ICmpInst *OptimizeMax(ICmpInst *Cond, IVStrideUse* &CondUse); | |||||||||
1674 | void OptimizeLoopTermCond(); | |||||||||
1675 | ||||||||||
1676 | void ChainInstruction(Instruction *UserInst, Instruction *IVOper, | |||||||||
1677 | SmallVectorImpl<ChainUsers> &ChainUsersVec); | |||||||||
1678 | void FinalizeChain(IVChain &Chain); | |||||||||
1679 | void CollectChains(); | |||||||||
1680 | void GenerateIVChain(const IVChain &Chain, SCEVExpander &Rewriter, | |||||||||
1681 | SmallVectorImpl<WeakVH> &DeadInsts); | |||||||||
1682 | ||||||||||
1683 | void CollectInterestingTypesAndFactors(); | |||||||||
1684 | void CollectFixupsAndInitialFormulae(); | |||||||||
1685 | ||||||||||
1686 | // Support for sharing of LSRUses between LSRFixups. | |||||||||
1687 | typedef DenseMap<LSRUse::SCEVUseKindPair, size_t> UseMapTy; | |||||||||
1688 | UseMapTy UseMap; | |||||||||
1689 | ||||||||||
1690 | bool reconcileNewOffset(LSRUse &LU, int64_t NewOffset, bool HasBaseReg, | |||||||||
1691 | LSRUse::KindType Kind, MemAccessTy AccessTy); | |||||||||
1692 | ||||||||||
1693 | std::pair<size_t, int64_t> getUse(const SCEV *&Expr, LSRUse::KindType Kind, | |||||||||
1694 | MemAccessTy AccessTy); | |||||||||
1695 | ||||||||||
1696 | void DeleteUse(LSRUse &LU, size_t LUIdx); | |||||||||
1697 | ||||||||||
1698 | LSRUse *FindUseWithSimilarFormula(const Formula &F, const LSRUse &OrigLU); | |||||||||
1699 | ||||||||||
1700 | void InsertInitialFormula(const SCEV *S, LSRUse &LU, size_t LUIdx); | |||||||||
1701 | void InsertSupplementalFormula(const SCEV *S, LSRUse &LU, size_t LUIdx); | |||||||||
1702 | void CountRegisters(const Formula &F, size_t LUIdx); | |||||||||
1703 | bool InsertFormula(LSRUse &LU, unsigned LUIdx, const Formula &F); | |||||||||
1704 | ||||||||||
1705 | void CollectLoopInvariantFixupsAndFormulae(); | |||||||||
1706 | ||||||||||
1707 | void GenerateReassociations(LSRUse &LU, unsigned LUIdx, Formula Base, | |||||||||
1708 | unsigned Depth = 0); | |||||||||
1709 | ||||||||||
1710 | void GenerateReassociationsImpl(LSRUse &LU, unsigned LUIdx, | |||||||||
1711 | const Formula &Base, unsigned Depth, | |||||||||
1712 | size_t Idx, bool IsScaledReg = false); | |||||||||
1713 | void GenerateCombinations(LSRUse &LU, unsigned LUIdx, Formula Base); | |||||||||
1714 | void GenerateSymbolicOffsetsImpl(LSRUse &LU, unsigned LUIdx, | |||||||||
1715 | const Formula &Base, size_t Idx, | |||||||||
1716 | bool IsScaledReg = false); | |||||||||
1717 | void GenerateSymbolicOffsets(LSRUse &LU, unsigned LUIdx, Formula Base); | |||||||||
1718 | void GenerateConstantOffsetsImpl(LSRUse &LU, unsigned LUIdx, | |||||||||
1719 | const Formula &Base, | |||||||||
1720 | const SmallVectorImpl<int64_t> &Worklist, | |||||||||
1721 | size_t Idx, bool IsScaledReg = false); | |||||||||
1722 | void GenerateConstantOffsets(LSRUse &LU, unsigned LUIdx, Formula Base); | |||||||||
1723 | void GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx, Formula Base); | |||||||||
1724 | void GenerateScales(LSRUse &LU, unsigned LUIdx, Formula Base); | |||||||||
1725 | void GenerateTruncates(LSRUse &LU, unsigned LUIdx, Formula Base); | |||||||||
1726 | void GenerateCrossUseConstantOffsets(); | |||||||||
1727 | void GenerateAllReuseFormulae(); | |||||||||
1728 | ||||||||||
1729 | void FilterOutUndesirableDedicatedRegisters(); | |||||||||
1730 | ||||||||||
1731 | size_t EstimateSearchSpaceComplexity() const; | |||||||||
1732 | void NarrowSearchSpaceByDetectingSupersets(); | |||||||||
1733 | void NarrowSearchSpaceByCollapsingUnrolledCode(); | |||||||||
1734 | void NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters(); | |||||||||
1735 | void NarrowSearchSpaceByPickingWinnerRegs(); | |||||||||
1736 | void NarrowSearchSpaceUsingHeuristics(); | |||||||||
1737 | ||||||||||
1738 | void SolveRecurse(SmallVectorImpl<const Formula *> &Solution, | |||||||||
1739 | Cost &SolutionCost, | |||||||||
1740 | SmallVectorImpl<const Formula *> &Workspace, | |||||||||
1741 | const Cost &CurCost, | |||||||||
1742 | const SmallPtrSet<const SCEV *, 16> &CurRegs, | |||||||||
1743 | DenseSet<const SCEV *> &VisitedRegs) const; | |||||||||
1744 | void Solve(SmallVectorImpl<const Formula *> &Solution) const; | |||||||||
1745 | ||||||||||
1746 | BasicBlock::iterator | |||||||||
1747 | HoistInsertPosition(BasicBlock::iterator IP, | |||||||||
1748 | const SmallVectorImpl<Instruction *> &Inputs) const; | |||||||||
1749 | BasicBlock::iterator | |||||||||
1750 | AdjustInsertPositionForExpand(BasicBlock::iterator IP, | |||||||||
1751 | const LSRFixup &LF, | |||||||||
1752 | const LSRUse &LU, | |||||||||
1753 | SCEVExpander &Rewriter) const; | |||||||||
1754 | ||||||||||
1755 | Value *Expand(const LSRUse &LU, const LSRFixup &LF, | |||||||||
1756 | const Formula &F, | |||||||||
1757 | BasicBlock::iterator IP, | |||||||||
1758 | SCEVExpander &Rewriter, | |||||||||
1759 | SmallVectorImpl<WeakVH> &DeadInsts) const; | |||||||||
1760 | void RewriteForPHI(PHINode *PN, const LSRUse &LU, const LSRFixup &LF, | |||||||||
1761 | const Formula &F, | |||||||||
1762 | SCEVExpander &Rewriter, | |||||||||
1763 | SmallVectorImpl<WeakVH> &DeadInsts) const; | |||||||||
1764 | void Rewrite(const LSRUse &LU, const LSRFixup &LF, | |||||||||
1765 | const Formula &F, | |||||||||
1766 | SCEVExpander &Rewriter, | |||||||||
1767 | SmallVectorImpl<WeakVH> &DeadInsts) const; | |||||||||
1768 | void ImplementSolution(const SmallVectorImpl<const Formula *> &Solution); | |||||||||
1769 | ||||||||||
1770 | public: | |||||||||
1771 | LSRInstance(Loop *L, IVUsers &IU, ScalarEvolution &SE, DominatorTree &DT, | |||||||||
1772 | LoopInfo &LI, const TargetTransformInfo &TTI); | |||||||||
1773 | ||||||||||
1774 | bool getChanged() const { return Changed; } | |||||||||
1775 | ||||||||||
1776 | void print_factors_and_types(raw_ostream &OS) const; | |||||||||
1777 | void print_fixups(raw_ostream &OS) const; | |||||||||
1778 | void print_uses(raw_ostream &OS) const; | |||||||||
1779 | void print(raw_ostream &OS) const; | |||||||||
1780 | void dump() const; | |||||||||
1781 | }; | |||||||||
1782 | ||||||||||
1783 | } | |||||||||
1784 | ||||||||||
1785 | /// If IV is used in a int-to-float cast inside the loop then try to eliminate | |||||||||
1786 | /// the cast operation. | |||||||||
1787 | void LSRInstance::OptimizeShadowIV() { | |||||||||
1788 | const SCEV *BackedgeTakenCount = SE.getBackedgeTakenCount(L); | |||||||||
1789 | if (isa<SCEVCouldNotCompute>(BackedgeTakenCount)) | |||||||||
1790 | return; | |||||||||
1791 | ||||||||||
1792 | for (IVUsers::const_iterator UI = IU.begin(), E = IU.end(); | |||||||||
1793 | UI != E; /* empty */) { | |||||||||
1794 | IVUsers::const_iterator CandidateUI = UI; | |||||||||
1795 | ++UI; | |||||||||
1796 | Instruction *ShadowUse = CandidateUI->getUser(); | |||||||||
1797 | Type *DestTy = nullptr; | |||||||||
1798 | bool IsSigned = false; | |||||||||
1799 | ||||||||||
1800 | /* If shadow use is a int->float cast then insert a second IV | |||||||||
1801 | to eliminate this cast. | |||||||||
1802 | ||||||||||
1803 | for (unsigned i = 0; i < n; ++i) | |||||||||
1804 | foo((double)i); | |||||||||
1805 | ||||||||||
1806 | is transformed into | |||||||||
1807 | ||||||||||
1808 | double d = 0.0; | |||||||||
1809 | for (unsigned i = 0; i < n; ++i, ++d) | |||||||||
1810 | foo(d); | |||||||||
1811 | */ | |||||||||
1812 | if (UIToFPInst *UCast = dyn_cast<UIToFPInst>(CandidateUI->getUser())) { | |||||||||
1813 | IsSigned = false; | |||||||||
1814 | DestTy = UCast->getDestTy(); | |||||||||
1815 | } | |||||||||
1816 | else if (SIToFPInst *SCast = dyn_cast<SIToFPInst>(CandidateUI->getUser())) { | |||||||||
1817 | IsSigned = true; | |||||||||
1818 | DestTy = SCast->getDestTy(); | |||||||||
1819 | } | |||||||||
1820 | if (!DestTy) continue; | |||||||||
1821 | ||||||||||
1822 | // If target does not support DestTy natively then do not apply | |||||||||
1823 | // this transformation. | |||||||||
1824 | if (!TTI.isTypeLegal(DestTy)) continue; | |||||||||
1825 | ||||||||||
1826 | PHINode *PH = dyn_cast<PHINode>(ShadowUse->getOperand(0)); | |||||||||
1827 | if (!PH) continue; | |||||||||
1828 | if (PH->getNumIncomingValues() != 2) continue; | |||||||||
1829 | ||||||||||
1830 | Type *SrcTy = PH->getType(); | |||||||||
1831 | int Mantissa = DestTy->getFPMantissaWidth(); | |||||||||
1832 | if (Mantissa == -1) continue; | |||||||||
1833 | if ((int)SE.getTypeSizeInBits(SrcTy) > Mantissa) | |||||||||
1834 | continue; | |||||||||
1835 | ||||||||||
1836 | unsigned Entry, Latch; | |||||||||
1837 | if (PH->getIncomingBlock(0) == L->getLoopPreheader()) { | |||||||||
1838 | Entry = 0; | |||||||||
1839 | Latch = 1; | |||||||||
1840 | } else { | |||||||||
1841 | Entry = 1; | |||||||||
1842 | Latch = 0; | |||||||||
1843 | } | |||||||||
1844 | ||||||||||
1845 | ConstantInt *Init = dyn_cast<ConstantInt>(PH->getIncomingValue(Entry)); | |||||||||
1846 | if (!Init) continue; | |||||||||
1847 | Constant *NewInit = ConstantFP::get(DestTy, IsSigned ? | |||||||||
1848 | (double)Init->getSExtValue() : | |||||||||
1849 | (double)Init->getZExtValue()); | |||||||||
1850 | ||||||||||
1851 | BinaryOperator *Incr = | |||||||||
1852 | dyn_cast<BinaryOperator>(PH->getIncomingValue(Latch)); | |||||||||
1853 | if (!Incr) continue; | |||||||||
1854 | if (Incr->getOpcode() != Instruction::Add | |||||||||
1855 | && Incr->getOpcode() != Instruction::Sub) | |||||||||
1856 | continue; | |||||||||
1857 | ||||||||||
1858 | /* Initialize new IV, double d = 0.0 in above example. */ | |||||||||
1859 | ConstantInt *C = nullptr; | |||||||||
1860 | if (Incr->getOperand(0) == PH) | |||||||||
1861 | C = dyn_cast<ConstantInt>(Incr->getOperand(1)); | |||||||||
1862 | else if (Incr->getOperand(1) == PH) | |||||||||
1863 | C = dyn_cast<ConstantInt>(Incr->getOperand(0)); | |||||||||
1864 | else | |||||||||
1865 | continue; | |||||||||
1866 | ||||||||||
1867 | if (!C) continue; | |||||||||
1868 | ||||||||||
1869 | // Ignore negative constants, as the code below doesn't handle them | |||||||||
1870 | // correctly. TODO: Remove this restriction. | |||||||||
1871 | if (!C->getValue().isStrictlyPositive()) continue; | |||||||||
1872 | ||||||||||
1873 | /* Add new PHINode. */ | |||||||||
1874 | PHINode *NewPH = PHINode::Create(DestTy, 2, "IV.S.", PH); | |||||||||
1875 | ||||||||||
1876 | /* create new increment. '++d' in above example. */ | |||||||||
1877 | Constant *CFP = ConstantFP::get(DestTy, C->getZExtValue()); | |||||||||
1878 | BinaryOperator *NewIncr = | |||||||||
1879 | BinaryOperator::Create(Incr->getOpcode() == Instruction::Add ? | |||||||||
1880 | Instruction::FAdd : Instruction::FSub, | |||||||||
1881 | NewPH, CFP, "IV.S.next.", Incr); | |||||||||
1882 | ||||||||||
1883 | NewPH->addIncoming(NewInit, PH->getIncomingBlock(Entry)); | |||||||||
1884 | NewPH->addIncoming(NewIncr, PH->getIncomingBlock(Latch)); | |||||||||
1885 | ||||||||||
1886 | /* Remove cast operation */ | |||||||||
1887 | ShadowUse->replaceAllUsesWith(NewPH); | |||||||||
1888 | ShadowUse->eraseFromParent(); | |||||||||
1889 | Changed = true; | |||||||||
1890 | break; | |||||||||
1891 | } | |||||||||
1892 | } | |||||||||
1893 | ||||||||||
1894 | /// If Cond has an operand that is an expression of an IV, set the IV user and | |||||||||
1895 | /// stride information and return true, otherwise return false. | |||||||||
1896 | bool LSRInstance::FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse) { | |||||||||
1897 | for (IVStrideUse &U : IU) | |||||||||
1898 | if (U.getUser() == Cond) { | |||||||||
1899 | // NOTE: we could handle setcc instructions with multiple uses here, but | |||||||||
1900 | // InstCombine does it as well for simple uses, it's not clear that it | |||||||||
1901 | // occurs enough in real life to handle. | |||||||||
1902 | CondUse = &U; | |||||||||
1903 | return true; | |||||||||
1904 | } | |||||||||
1905 | return false; | |||||||||
1906 | } | |||||||||
1907 | ||||||||||
1908 | /// Rewrite the loop's terminating condition if it uses a max computation. | |||||||||
1909 | /// | |||||||||
1910 | /// This is a narrow solution to a specific, but acute, problem. For loops | |||||||||
1911 | /// like this: | |||||||||
1912 | /// | |||||||||
1913 | /// i = 0; | |||||||||
1914 | /// do { | |||||||||
1915 | /// p[i] = 0.0; | |||||||||
1916 | /// } while (++i < n); | |||||||||
1917 | /// | |||||||||
1918 | /// the trip count isn't just 'n', because 'n' might not be positive. And | |||||||||
1919 | /// unfortunately this can come up even for loops where the user didn't use | |||||||||
1920 | /// a C do-while loop. For example, seemingly well-behaved top-test loops | |||||||||
1921 | /// will commonly be lowered like this: | |||||||||
1922 | // | |||||||||
1923 | /// if (n > 0) { | |||||||||
1924 | /// i = 0; | |||||||||
1925 | /// do { | |||||||||
1926 | /// p[i] = 0.0; | |||||||||
1927 | /// } while (++i < n); | |||||||||
1928 | /// } | |||||||||
1929 | /// | |||||||||
1930 | /// and then it's possible for subsequent optimization to obscure the if | |||||||||
1931 | /// test in such a way that indvars can't find it. | |||||||||
1932 | /// | |||||||||
1933 | /// When indvars can't find the if test in loops like this, it creates a | |||||||||
1934 | /// max expression, which allows it to give the loop a canonical | |||||||||
1935 | /// induction variable: | |||||||||
1936 | /// | |||||||||
1937 | /// i = 0; | |||||||||
1938 | /// max = n < 1 ? 1 : n; | |||||||||
1939 | /// do { | |||||||||
1940 | /// p[i] = 0.0; | |||||||||
1941 | /// } while (++i != max); | |||||||||
1942 | /// | |||||||||
1943 | /// Canonical induction variables are necessary because the loop passes | |||||||||
1944 | /// are designed around them. The most obvious example of this is the | |||||||||
1945 | /// LoopInfo analysis, which doesn't remember trip count values. It | |||||||||
1946 | /// expects to be able to rediscover the trip count each time it is | |||||||||
1947 | /// needed, and it does this using a simple analysis that only succeeds if | |||||||||
1948 | /// the loop has a canonical induction variable. | |||||||||
1949 | /// | |||||||||
1950 | /// However, when it comes time to generate code, the maximum operation | |||||||||
1951 | /// can be quite costly, especially if it's inside of an outer loop. | |||||||||
1952 | /// | |||||||||
1953 | /// This function solves this problem by detecting this type of loop and | |||||||||
1954 | /// rewriting their conditions from ICMP_NE back to ICMP_SLT, and deleting | |||||||||
1955 | /// the instructions for the maximum computation. | |||||||||
1956 | /// | |||||||||
1957 | ICmpInst *LSRInstance::OptimizeMax(ICmpInst *Cond, IVStrideUse* &CondUse) { | |||||||||
1958 | // Check that the loop matches the pattern we're looking for. | |||||||||
1959 | if (Cond->getPredicate() != CmpInst::ICMP_EQ && | |||||||||
1960 | Cond->getPredicate() != CmpInst::ICMP_NE) | |||||||||
1961 | return Cond; | |||||||||
1962 | ||||||||||
1963 | SelectInst *Sel = dyn_cast<SelectInst>(Cond->getOperand(1)); | |||||||||
1964 | if (!Sel || !Sel->hasOneUse()) return Cond; | |||||||||
1965 | ||||||||||
1966 | const SCEV *BackedgeTakenCount = SE.getBackedgeTakenCount(L); | |||||||||
1967 | if (isa<SCEVCouldNotCompute>(BackedgeTakenCount)) | |||||||||
1968 | return Cond; | |||||||||
1969 | const SCEV *One = SE.getConstant(BackedgeTakenCount->getType(), 1); | |||||||||
1970 | ||||||||||
1971 | // Add one to the backedge-taken count to get the trip count. | |||||||||
1972 | const SCEV *IterationCount = SE.getAddExpr(One, BackedgeTakenCount); | |||||||||
1973 | if (IterationCount != SE.getSCEV(Sel)) return Cond; | |||||||||
1974 | ||||||||||
1975 | // Check for a max calculation that matches the pattern. There's no check | |||||||||
1976 | // for ICMP_ULE here because the comparison would be with zero, which | |||||||||
1977 | // isn't interesting. | |||||||||
1978 | CmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE; | |||||||||
1979 | const SCEVNAryExpr *Max = nullptr; | |||||||||
1980 | if (const SCEVSMaxExpr *S = dyn_cast<SCEVSMaxExpr>(BackedgeTakenCount)) { | |||||||||
1981 | Pred = ICmpInst::ICMP_SLE; | |||||||||
1982 | Max = S; | |||||||||
1983 | } else if (const SCEVSMaxExpr *S = dyn_cast<SCEVSMaxExpr>(IterationCount)) { | |||||||||
1984 | Pred = ICmpInst::ICMP_SLT; | |||||||||
1985 | Max = S; | |||||||||
1986 | } else if (const SCEVUMaxExpr *U = dyn_cast<SCEVUMaxExpr>(IterationCount)) { | |||||||||
1987 | Pred = ICmpInst::ICMP_ULT; | |||||||||
1988 | Max = U; | |||||||||
1989 | } else { | |||||||||
1990 | // No match; bail. | |||||||||
1991 | return Cond; | |||||||||
1992 | } | |||||||||
1993 | ||||||||||
1994 | // To handle a max with more than two operands, this optimization would | |||||||||
1995 | // require additional checking and setup. | |||||||||
1996 | if (Max->getNumOperands() != 2) | |||||||||
1997 | return Cond; | |||||||||
1998 | ||||||||||
1999 | const SCEV *MaxLHS = Max->getOperand(0); | |||||||||
2000 | const SCEV *MaxRHS = Max->getOperand(1); | |||||||||
2001 | ||||||||||
2002 | // ScalarEvolution canonicalizes constants to the left. For < and >, look | |||||||||
2003 | // for a comparison with 1. For <= and >=, a comparison with zero. | |||||||||
2004 | if (!MaxLHS || | |||||||||
2005 | (ICmpInst::isTrueWhenEqual(Pred) ? !MaxLHS->isZero() : (MaxLHS != One))) | |||||||||
2006 | return Cond; | |||||||||
2007 | ||||||||||
2008 | // Check the relevant induction variable for conformance to | |||||||||
2009 | // the pattern. | |||||||||
2010 | const SCEV *IV = SE.getSCEV(Cond->getOperand(0)); | |||||||||
2011 | const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(IV); | |||||||||
2012 | if (!AR || !AR->isAffine() || | |||||||||
2013 | AR->getStart() != One || | |||||||||
2014 | AR->getStepRecurrence(SE) != One) | |||||||||
2015 | return Cond; | |||||||||
2016 | ||||||||||
2017 | assert(AR->getLoop() == L &&((AR->getLoop() == L && "Loop condition operand is an addrec in a different loop!" ) ? static_cast<void> (0) : __assert_fail ("AR->getLoop() == L && \"Loop condition operand is an addrec in a different loop!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 2018, __PRETTY_FUNCTION__)) | |||||||||
2018 | "Loop condition operand is an addrec in a different loop!")((AR->getLoop() == L && "Loop condition operand is an addrec in a different loop!" ) ? static_cast<void> (0) : __assert_fail ("AR->getLoop() == L && \"Loop condition operand is an addrec in a different loop!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 2018, __PRETTY_FUNCTION__)); | |||||||||
2019 | ||||||||||
2020 | // Check the right operand of the select, and remember it, as it will | |||||||||
2021 | // be used in the new comparison instruction. | |||||||||
2022 | Value *NewRHS = nullptr; | |||||||||
2023 | if (ICmpInst::isTrueWhenEqual(Pred)) { | |||||||||
2024 | // Look for n+1, and grab n. | |||||||||
2025 | if (AddOperator *BO = dyn_cast<AddOperator>(Sel->getOperand(1))) | |||||||||
2026 | if (ConstantInt *BO1 = dyn_cast<ConstantInt>(BO->getOperand(1))) | |||||||||
2027 | if (BO1->isOne() && SE.getSCEV(BO->getOperand(0)) == MaxRHS) | |||||||||
2028 | NewRHS = BO->getOperand(0); | |||||||||
2029 | if (AddOperator *BO = dyn_cast<AddOperator>(Sel->getOperand(2))) | |||||||||
2030 | if (ConstantInt *BO1 = dyn_cast<ConstantInt>(BO->getOperand(1))) | |||||||||
2031 | if (BO1->isOne() && SE.getSCEV(BO->getOperand(0)) == MaxRHS) | |||||||||
2032 | NewRHS = BO->getOperand(0); | |||||||||
2033 | if (!NewRHS) | |||||||||
2034 | return Cond; | |||||||||
2035 | } else if (SE.getSCEV(Sel->getOperand(1)) == MaxRHS) | |||||||||
2036 | NewRHS = Sel->getOperand(1); | |||||||||
2037 | else if (SE.getSCEV(Sel->getOperand(2)) == MaxRHS) | |||||||||
2038 | NewRHS = Sel->getOperand(2); | |||||||||
2039 | else if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(MaxRHS)) | |||||||||
2040 | NewRHS = SU->getValue(); | |||||||||
2041 | else | |||||||||
2042 | // Max doesn't match expected pattern. | |||||||||
2043 | return Cond; | |||||||||
2044 | ||||||||||
2045 | // Determine the new comparison opcode. It may be signed or unsigned, | |||||||||
2046 | // and the original comparison may be either equality or inequality. | |||||||||
2047 | if (Cond->getPredicate() == CmpInst::ICMP_EQ) | |||||||||
2048 | Pred = CmpInst::getInversePredicate(Pred); | |||||||||
2049 | ||||||||||
2050 | // Ok, everything looks ok to change the condition into an SLT or SGE and | |||||||||
2051 | // delete the max calculation. | |||||||||
2052 | ICmpInst *NewCond = | |||||||||
2053 | new ICmpInst(Cond, Pred, Cond->getOperand(0), NewRHS, "scmp"); | |||||||||
2054 | ||||||||||
2055 | // Delete the max calculation instructions. | |||||||||
2056 | Cond->replaceAllUsesWith(NewCond); | |||||||||
2057 | CondUse->setUser(NewCond); | |||||||||
2058 | Instruction *Cmp = cast<Instruction>(Sel->getOperand(0)); | |||||||||
2059 | Cond->eraseFromParent(); | |||||||||
2060 | Sel->eraseFromParent(); | |||||||||
2061 | if (Cmp->use_empty()) | |||||||||
2062 | Cmp->eraseFromParent(); | |||||||||
2063 | return NewCond; | |||||||||
2064 | } | |||||||||
2065 | ||||||||||
2066 | /// Change loop terminating condition to use the postinc iv when possible. | |||||||||
2067 | void | |||||||||
2068 | LSRInstance::OptimizeLoopTermCond() { | |||||||||
2069 | SmallPtrSet<Instruction *, 4> PostIncs; | |||||||||
2070 | ||||||||||
2071 | // We need a different set of heuristics for rotated and non-rotated loops. | |||||||||
2072 | // If a loop is rotated then the latch is also the backedge, so inserting | |||||||||
2073 | // post-inc expressions just before the latch is ideal. To reduce live ranges | |||||||||
2074 | // it also makes sense to rewrite terminating conditions to use post-inc | |||||||||
2075 | // expressions. | |||||||||
2076 | // | |||||||||
2077 | // If the loop is not rotated then the latch is not a backedge; the latch | |||||||||
2078 | // check is done in the loop head. Adding post-inc expressions before the | |||||||||
2079 | // latch will cause overlapping live-ranges of pre-inc and post-inc expressions | |||||||||
2080 | // in the loop body. In this case we do *not* want to use post-inc expressions | |||||||||
2081 | // in the latch check, and we want to insert post-inc expressions before | |||||||||
2082 | // the backedge. | |||||||||
2083 | BasicBlock *LatchBlock = L->getLoopLatch(); | |||||||||
2084 | SmallVector<BasicBlock*, 8> ExitingBlocks; | |||||||||
2085 | L->getExitingBlocks(ExitingBlocks); | |||||||||
2086 | if (llvm::all_of(ExitingBlocks, [&LatchBlock](const BasicBlock *BB) { | |||||||||
2087 | return LatchBlock != BB; | |||||||||
2088 | })) { | |||||||||
2089 | // The backedge doesn't exit the loop; treat this as a head-tested loop. | |||||||||
2090 | IVIncInsertPos = LatchBlock->getTerminator(); | |||||||||
2091 | return; | |||||||||
2092 | } | |||||||||
2093 | ||||||||||
2094 | // Otherwise treat this as a rotated loop. | |||||||||
2095 | for (BasicBlock *ExitingBlock : ExitingBlocks) { | |||||||||
2096 | ||||||||||
2097 | // Get the terminating condition for the loop if possible. If we | |||||||||
2098 | // can, we want to change it to use a post-incremented version of its | |||||||||
2099 | // induction variable, to allow coalescing the live ranges for the IV into | |||||||||
2100 | // one register value. | |||||||||
2101 | ||||||||||
2102 | BranchInst *TermBr = dyn_cast<BranchInst>(ExitingBlock->getTerminator()); | |||||||||
2103 | if (!TermBr) | |||||||||
2104 | continue; | |||||||||
2105 | // FIXME: Overly conservative, termination condition could be an 'or' etc.. | |||||||||
2106 | if (TermBr->isUnconditional() || !isa<ICmpInst>(TermBr->getCondition())) | |||||||||
2107 | continue; | |||||||||
2108 | ||||||||||
2109 | // Search IVUsesByStride to find Cond's IVUse if there is one. | |||||||||
2110 | IVStrideUse *CondUse = nullptr; | |||||||||
2111 | ICmpInst *Cond = cast<ICmpInst>(TermBr->getCondition()); | |||||||||
2112 | if (!FindIVUserForCond(Cond, CondUse)) | |||||||||
2113 | continue; | |||||||||
2114 | ||||||||||
2115 | // If the trip count is computed in terms of a max (due to ScalarEvolution | |||||||||
2116 | // being unable to find a sufficient guard, for example), change the loop | |||||||||
2117 | // comparison to use SLT or ULT instead of NE. | |||||||||
2118 | // One consequence of doing this now is that it disrupts the count-down | |||||||||
2119 | // optimization. That's not always a bad thing though, because in such | |||||||||
2120 | // cases it may still be worthwhile to avoid a max. | |||||||||
2121 | Cond = OptimizeMax(Cond, CondUse); | |||||||||
2122 | ||||||||||
2123 | // If this exiting block dominates the latch block, it may also use | |||||||||
2124 | // the post-inc value if it won't be shared with other uses. | |||||||||
2125 | // Check for dominance. | |||||||||
2126 | if (!DT.dominates(ExitingBlock, LatchBlock)) | |||||||||
2127 | continue; | |||||||||
2128 | ||||||||||
2129 | // Conservatively avoid trying to use the post-inc value in non-latch | |||||||||
2130 | // exits if there may be pre-inc users in intervening blocks. | |||||||||
2131 | if (LatchBlock != ExitingBlock) | |||||||||
2132 | for (IVUsers::const_iterator UI = IU.begin(), E = IU.end(); UI != E; ++UI) | |||||||||
2133 | // Test if the use is reachable from the exiting block. This dominator | |||||||||
2134 | // query is a conservative approximation of reachability. | |||||||||
2135 | if (&*UI != CondUse && | |||||||||
2136 | !DT.properlyDominates(UI->getUser()->getParent(), ExitingBlock)) { | |||||||||
2137 | // Conservatively assume there may be reuse if the quotient of their | |||||||||
2138 | // strides could be a legal scale. | |||||||||
2139 | const SCEV *A = IU.getStride(*CondUse, L); | |||||||||
2140 | const SCEV *B = IU.getStride(*UI, L); | |||||||||
2141 | if (!A || !B) continue; | |||||||||
2142 | if (SE.getTypeSizeInBits(A->getType()) != | |||||||||
2143 | SE.getTypeSizeInBits(B->getType())) { | |||||||||
2144 | if (SE.getTypeSizeInBits(A->getType()) > | |||||||||
2145 | SE.getTypeSizeInBits(B->getType())) | |||||||||
2146 | B = SE.getSignExtendExpr(B, A->getType()); | |||||||||
2147 | else | |||||||||
2148 | A = SE.getSignExtendExpr(A, B->getType()); | |||||||||
2149 | } | |||||||||
2150 | if (const SCEVConstant *D = | |||||||||
2151 | dyn_cast_or_null<SCEVConstant>(getExactSDiv(B, A, SE))) { | |||||||||
2152 | const ConstantInt *C = D->getValue(); | |||||||||
2153 | // Stride of one or negative one can have reuse with non-addresses. | |||||||||
2154 | if (C->isOne() || C->isAllOnesValue()) | |||||||||
2155 | goto decline_post_inc; | |||||||||
2156 | // Avoid weird situations. | |||||||||
2157 | if (C->getValue().getMinSignedBits() >= 64 || | |||||||||
2158 | C->getValue().isMinSignedValue()) | |||||||||
2159 | goto decline_post_inc; | |||||||||
2160 | // Check for possible scaled-address reuse. | |||||||||
2161 | MemAccessTy AccessTy = getAccessType(UI->getUser()); | |||||||||
2162 | int64_t Scale = C->getSExtValue(); | |||||||||
2163 | if (TTI.isLegalAddressingMode(AccessTy.MemTy, /*BaseGV=*/nullptr, | |||||||||
2164 | /*BaseOffset=*/0, | |||||||||
2165 | /*HasBaseReg=*/false, Scale, | |||||||||
2166 | AccessTy.AddrSpace)) | |||||||||
2167 | goto decline_post_inc; | |||||||||
2168 | Scale = -Scale; | |||||||||
2169 | if (TTI.isLegalAddressingMode(AccessTy.MemTy, /*BaseGV=*/nullptr, | |||||||||
2170 | /*BaseOffset=*/0, | |||||||||
2171 | /*HasBaseReg=*/false, Scale, | |||||||||
2172 | AccessTy.AddrSpace)) | |||||||||
2173 | goto decline_post_inc; | |||||||||
2174 | } | |||||||||
2175 | } | |||||||||
2176 | ||||||||||
2177 | DEBUG(dbgs() << " Change loop exiting icmp to use postinc iv: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Change loop exiting icmp to use postinc iv: " << *Cond << '\n'; } } while (false) | |||||||||
2178 | << *Cond << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Change loop exiting icmp to use postinc iv: " << *Cond << '\n'; } } while (false); | |||||||||
2179 | ||||||||||
2180 | // It's possible for the setcc instruction to be anywhere in the loop, and | |||||||||
2181 | // possible for it to have multiple users. If it is not immediately before | |||||||||
2182 | // the exiting block branch, move it. | |||||||||
2183 | if (&*++BasicBlock::iterator(Cond) != TermBr) { | |||||||||
2184 | if (Cond->hasOneUse()) { | |||||||||
2185 | Cond->moveBefore(TermBr); | |||||||||
2186 | } else { | |||||||||
2187 | // Clone the terminating condition and insert into the loopend. | |||||||||
2188 | ICmpInst *OldCond = Cond; | |||||||||
2189 | Cond = cast<ICmpInst>(Cond->clone()); | |||||||||
2190 | Cond->setName(L->getHeader()->getName() + ".termcond"); | |||||||||
2191 | ExitingBlock->getInstList().insert(TermBr->getIterator(), Cond); | |||||||||
2192 | ||||||||||
2193 | // Clone the IVUse, as the old use still exists! | |||||||||
2194 | CondUse = &IU.AddUser(Cond, CondUse->getOperandValToReplace()); | |||||||||
2195 | TermBr->replaceUsesOfWith(OldCond, Cond); | |||||||||
2196 | } | |||||||||
2197 | } | |||||||||
2198 | ||||||||||
2199 | // If we get to here, we know that we can transform the setcc instruction to | |||||||||
2200 | // use the post-incremented version of the IV, allowing us to coalesce the | |||||||||
2201 | // live ranges for the IV correctly. | |||||||||
2202 | CondUse->transformToPostInc(L); | |||||||||
2203 | Changed = true; | |||||||||
2204 | ||||||||||
2205 | PostIncs.insert(Cond); | |||||||||
2206 | decline_post_inc:; | |||||||||
2207 | } | |||||||||
2208 | ||||||||||
2209 | // Determine an insertion point for the loop induction variable increment. It | |||||||||
2210 | // must dominate all the post-inc comparisons we just set up, and it must | |||||||||
2211 | // dominate the loop latch edge. | |||||||||
2212 | IVIncInsertPos = L->getLoopLatch()->getTerminator(); | |||||||||
2213 | for (Instruction *Inst : PostIncs) { | |||||||||
2214 | BasicBlock *BB = | |||||||||
2215 | DT.findNearestCommonDominator(IVIncInsertPos->getParent(), | |||||||||
2216 | Inst->getParent()); | |||||||||
2217 | if (BB == Inst->getParent()) | |||||||||
2218 | IVIncInsertPos = Inst; | |||||||||
2219 | else if (BB != IVIncInsertPos->getParent()) | |||||||||
2220 | IVIncInsertPos = BB->getTerminator(); | |||||||||
2221 | } | |||||||||
2222 | } | |||||||||
2223 | ||||||||||
2224 | /// Determine if the given use can accommodate a fixup at the given offset and | |||||||||
2225 | /// other details. If so, update the use and return true. | |||||||||
2226 | bool LSRInstance::reconcileNewOffset(LSRUse &LU, int64_t NewOffset, | |||||||||
2227 | bool HasBaseReg, LSRUse::KindType Kind, | |||||||||
2228 | MemAccessTy AccessTy) { | |||||||||
2229 | int64_t NewMinOffset = LU.MinOffset; | |||||||||
2230 | int64_t NewMaxOffset = LU.MaxOffset; | |||||||||
2231 | MemAccessTy NewAccessTy = AccessTy; | |||||||||
2232 | ||||||||||
2233 | // Check for a mismatched kind. It's tempting to collapse mismatched kinds to | |||||||||
2234 | // something conservative, however this can pessimize in the case that one of | |||||||||
2235 | // the uses will have all its uses outside the loop, for example. | |||||||||
2236 | if (LU.Kind != Kind) | |||||||||
2237 | return false; | |||||||||
2238 | ||||||||||
2239 | // Check for a mismatched access type, and fall back conservatively as needed. | |||||||||
2240 | // TODO: Be less conservative when the type is similar and can use the same | |||||||||
2241 | // addressing modes. | |||||||||
2242 | if (Kind == LSRUse::Address) { | |||||||||
2243 | if (AccessTy != LU.AccessTy) | |||||||||
2244 | NewAccessTy = MemAccessTy::getUnknown(AccessTy.MemTy->getContext()); | |||||||||
2245 | } | |||||||||
2246 | ||||||||||
2247 | // Conservatively assume HasBaseReg is true for now. | |||||||||
2248 | if (NewOffset < LU.MinOffset) { | |||||||||
2249 | if (!isAlwaysFoldable(TTI, Kind, NewAccessTy, /*BaseGV=*/nullptr, | |||||||||
2250 | LU.MaxOffset - NewOffset, HasBaseReg)) | |||||||||
2251 | return false; | |||||||||
2252 | NewMinOffset = NewOffset; | |||||||||
2253 | } else if (NewOffset > LU.MaxOffset) { | |||||||||
2254 | if (!isAlwaysFoldable(TTI, Kind, NewAccessTy, /*BaseGV=*/nullptr, | |||||||||
2255 | NewOffset - LU.MinOffset, HasBaseReg)) | |||||||||
2256 | return false; | |||||||||
2257 | NewMaxOffset = NewOffset; | |||||||||
2258 | } | |||||||||
2259 | ||||||||||
2260 | // Update the use. | |||||||||
2261 | LU.MinOffset = NewMinOffset; | |||||||||
2262 | LU.MaxOffset = NewMaxOffset; | |||||||||
2263 | LU.AccessTy = NewAccessTy; | |||||||||
2264 | return true; | |||||||||
2265 | } | |||||||||
2266 | ||||||||||
2267 | /// Return an LSRUse index and an offset value for a fixup which needs the given | |||||||||
2268 | /// expression, with the given kind and optional access type. Either reuse an | |||||||||
2269 | /// existing use or create a new one, as needed. | |||||||||
2270 | std::pair<size_t, int64_t> LSRInstance::getUse(const SCEV *&Expr, | |||||||||
2271 | LSRUse::KindType Kind, | |||||||||
2272 | MemAccessTy AccessTy) { | |||||||||
2273 | const SCEV *Copy = Expr; | |||||||||
2274 | int64_t Offset = ExtractImmediate(Expr, SE); | |||||||||
2275 | ||||||||||
2276 | // Basic uses can't accept any offset, for example. | |||||||||
2277 | if (!isAlwaysFoldable(TTI, Kind, AccessTy, /*BaseGV=*/ nullptr, | |||||||||
2278 | Offset, /*HasBaseReg=*/ true)) { | |||||||||
2279 | Expr = Copy; | |||||||||
2280 | Offset = 0; | |||||||||
2281 | } | |||||||||
2282 | ||||||||||
2283 | std::pair<UseMapTy::iterator, bool> P = | |||||||||
2284 | UseMap.insert(std::make_pair(LSRUse::SCEVUseKindPair(Expr, Kind), 0)); | |||||||||
2285 | if (!P.second) { | |||||||||
2286 | // A use already existed with this base. | |||||||||
2287 | size_t LUIdx = P.first->second; | |||||||||
2288 | LSRUse &LU = Uses[LUIdx]; | |||||||||
2289 | if (reconcileNewOffset(LU, Offset, /*HasBaseReg=*/true, Kind, AccessTy)) | |||||||||
2290 | // Reuse this use. | |||||||||
2291 | return std::make_pair(LUIdx, Offset); | |||||||||
2292 | } | |||||||||
2293 | ||||||||||
2294 | // Create a new use. | |||||||||
2295 | size_t LUIdx = Uses.size(); | |||||||||
2296 | P.first->second = LUIdx; | |||||||||
2297 | Uses.push_back(LSRUse(Kind, AccessTy)); | |||||||||
2298 | LSRUse &LU = Uses[LUIdx]; | |||||||||
2299 | ||||||||||
2300 | LU.MinOffset = Offset; | |||||||||
2301 | LU.MaxOffset = Offset; | |||||||||
2302 | return std::make_pair(LUIdx, Offset); | |||||||||
2303 | } | |||||||||
2304 | ||||||||||
2305 | /// Delete the given use from the Uses list. | |||||||||
2306 | void LSRInstance::DeleteUse(LSRUse &LU, size_t LUIdx) { | |||||||||
2307 | if (&LU != &Uses.back()) | |||||||||
2308 | std::swap(LU, Uses.back()); | |||||||||
2309 | Uses.pop_back(); | |||||||||
2310 | ||||||||||
2311 | // Update RegUses. | |||||||||
2312 | RegUses.swapAndDropUse(LUIdx, Uses.size()); | |||||||||
2313 | } | |||||||||
2314 | ||||||||||
2315 | /// Look for a use distinct from OrigLU which is has a formula that has the same | |||||||||
2316 | /// registers as the given formula. | |||||||||
2317 | LSRUse * | |||||||||
2318 | LSRInstance::FindUseWithSimilarFormula(const Formula &OrigF, | |||||||||
2319 | const LSRUse &OrigLU) { | |||||||||
2320 | // Search all uses for the formula. This could be more clever. | |||||||||
2321 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { | |||||||||
2322 | LSRUse &LU = Uses[LUIdx]; | |||||||||
2323 | // Check whether this use is close enough to OrigLU, to see whether it's | |||||||||
2324 | // worthwhile looking through its formulae. | |||||||||
2325 | // Ignore ICmpZero uses because they may contain formulae generated by | |||||||||
2326 | // GenerateICmpZeroScales, in which case adding fixup offsets may | |||||||||
2327 | // be invalid. | |||||||||
2328 | if (&LU != &OrigLU && | |||||||||
2329 | LU.Kind != LSRUse::ICmpZero && | |||||||||
2330 | LU.Kind == OrigLU.Kind && OrigLU.AccessTy == LU.AccessTy && | |||||||||
2331 | LU.WidestFixupType == OrigLU.WidestFixupType && | |||||||||
2332 | LU.HasFormulaWithSameRegs(OrigF)) { | |||||||||
2333 | // Scan through this use's formulae. | |||||||||
2334 | for (const Formula &F : LU.Formulae) { | |||||||||
2335 | // Check to see if this formula has the same registers and symbols | |||||||||
2336 | // as OrigF. | |||||||||
2337 | if (F.BaseRegs == OrigF.BaseRegs && | |||||||||
2338 | F.ScaledReg == OrigF.ScaledReg && | |||||||||
2339 | F.BaseGV == OrigF.BaseGV && | |||||||||
2340 | F.Scale == OrigF.Scale && | |||||||||
2341 | F.UnfoldedOffset == OrigF.UnfoldedOffset) { | |||||||||
2342 | if (F.BaseOffset == 0) | |||||||||
2343 | return &LU; | |||||||||
2344 | // This is the formula where all the registers and symbols matched; | |||||||||
2345 | // there aren't going to be any others. Since we declined it, we | |||||||||
2346 | // can skip the rest of the formulae and proceed to the next LSRUse. | |||||||||
2347 | break; | |||||||||
2348 | } | |||||||||
2349 | } | |||||||||
2350 | } | |||||||||
2351 | } | |||||||||
2352 | ||||||||||
2353 | // Nothing looked good. | |||||||||
2354 | return nullptr; | |||||||||
2355 | } | |||||||||
2356 | ||||||||||
2357 | void LSRInstance::CollectInterestingTypesAndFactors() { | |||||||||
2358 | SmallSetVector<const SCEV *, 4> Strides; | |||||||||
2359 | ||||||||||
2360 | // Collect interesting types and strides. | |||||||||
2361 | SmallVector<const SCEV *, 4> Worklist; | |||||||||
2362 | for (const IVStrideUse &U : IU) { | |||||||||
2363 | const SCEV *Expr = IU.getExpr(U); | |||||||||
2364 | ||||||||||
2365 | // Collect interesting types. | |||||||||
2366 | Types.insert(SE.getEffectiveSCEVType(Expr->getType())); | |||||||||
2367 | ||||||||||
2368 | // Add strides for mentioned loops. | |||||||||
2369 | Worklist.push_back(Expr); | |||||||||
2370 | do { | |||||||||
2371 | const SCEV *S = Worklist.pop_back_val(); | |||||||||
2372 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) { | |||||||||
2373 | if (AR->getLoop() == L) | |||||||||
2374 | Strides.insert(AR->getStepRecurrence(SE)); | |||||||||
2375 | Worklist.push_back(AR->getStart()); | |||||||||
2376 | } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) { | |||||||||
2377 | Worklist.append(Add->op_begin(), Add->op_end()); | |||||||||
2378 | } | |||||||||
2379 | } while (!Worklist.empty()); | |||||||||
2380 | } | |||||||||
2381 | ||||||||||
2382 | // Compute interesting factors from the set of interesting strides. | |||||||||
2383 | for (SmallSetVector<const SCEV *, 4>::const_iterator | |||||||||
2384 | I = Strides.begin(), E = Strides.end(); I != E; ++I) | |||||||||
2385 | for (SmallSetVector<const SCEV *, 4>::const_iterator NewStrideIter = | |||||||||
2386 | std::next(I); NewStrideIter != E; ++NewStrideIter) { | |||||||||
2387 | const SCEV *OldStride = *I; | |||||||||
2388 | const SCEV *NewStride = *NewStrideIter; | |||||||||
2389 | ||||||||||
2390 | if (SE.getTypeSizeInBits(OldStride->getType()) != | |||||||||
2391 | SE.getTypeSizeInBits(NewStride->getType())) { | |||||||||
2392 | if (SE.getTypeSizeInBits(OldStride->getType()) > | |||||||||
2393 | SE.getTypeSizeInBits(NewStride->getType())) | |||||||||
2394 | NewStride = SE.getSignExtendExpr(NewStride, OldStride->getType()); | |||||||||
2395 | else | |||||||||
2396 | OldStride = SE.getSignExtendExpr(OldStride, NewStride->getType()); | |||||||||
2397 | } | |||||||||
2398 | if (const SCEVConstant *Factor = | |||||||||
2399 | dyn_cast_or_null<SCEVConstant>(getExactSDiv(NewStride, OldStride, | |||||||||
2400 | SE, true))) { | |||||||||
2401 | if (Factor->getAPInt().getMinSignedBits() <= 64) | |||||||||
2402 | Factors.insert(Factor->getAPInt().getSExtValue()); | |||||||||
2403 | } else if (const SCEVConstant *Factor = | |||||||||
2404 | dyn_cast_or_null<SCEVConstant>(getExactSDiv(OldStride, | |||||||||
2405 | NewStride, | |||||||||
2406 | SE, true))) { | |||||||||
2407 | if (Factor->getAPInt().getMinSignedBits() <= 64) | |||||||||
2408 | Factors.insert(Factor->getAPInt().getSExtValue()); | |||||||||
2409 | } | |||||||||
2410 | } | |||||||||
2411 | ||||||||||
2412 | // If all uses use the same type, don't bother looking for truncation-based | |||||||||
2413 | // reuse. | |||||||||
2414 | if (Types.size() == 1) | |||||||||
2415 | Types.clear(); | |||||||||
2416 | ||||||||||
2417 | DEBUG(print_factors_and_types(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { print_factors_and_types(dbgs()); } } while (false); | |||||||||
2418 | } | |||||||||
2419 | ||||||||||
2420 | /// Helper for CollectChains that finds an IV operand (computed by an AddRec in | |||||||||
2421 | /// this loop) within [OI,OE) or returns OE. If IVUsers mapped Instructions to | |||||||||
2422 | /// IVStrideUses, we could partially skip this. | |||||||||
2423 | static User::op_iterator | |||||||||
2424 | findIVOperand(User::op_iterator OI, User::op_iterator OE, | |||||||||
2425 | Loop *L, ScalarEvolution &SE) { | |||||||||
2426 | for(; OI != OE; ++OI) { | |||||||||
2427 | if (Instruction *Oper = dyn_cast<Instruction>(*OI)) { | |||||||||
2428 | if (!SE.isSCEVable(Oper->getType())) | |||||||||
2429 | continue; | |||||||||
2430 | ||||||||||
2431 | if (const SCEVAddRecExpr *AR = | |||||||||
2432 | dyn_cast<SCEVAddRecExpr>(SE.getSCEV(Oper))) { | |||||||||
2433 | if (AR->getLoop() == L) | |||||||||
2434 | break; | |||||||||
2435 | } | |||||||||
2436 | } | |||||||||
2437 | } | |||||||||
2438 | return OI; | |||||||||
2439 | } | |||||||||
2440 | ||||||||||
2441 | /// IVChain logic must consistenctly peek base TruncInst operands, so wrap it in | |||||||||
2442 | /// a convenient helper. | |||||||||
2443 | static Value *getWideOperand(Value *Oper) { | |||||||||
2444 | if (TruncInst *Trunc = dyn_cast<TruncInst>(Oper)) | |||||||||
2445 | return Trunc->getOperand(0); | |||||||||
2446 | return Oper; | |||||||||
2447 | } | |||||||||
2448 | ||||||||||
2449 | /// Return true if we allow an IV chain to include both types. | |||||||||
2450 | static bool isCompatibleIVType(Value *LVal, Value *RVal) { | |||||||||
2451 | Type *LType = LVal->getType(); | |||||||||
2452 | Type *RType = RVal->getType(); | |||||||||
2453 | return (LType == RType) || (LType->isPointerTy() && RType->isPointerTy()); | |||||||||
2454 | } | |||||||||
2455 | ||||||||||
2456 | /// Return an approximation of this SCEV expression's "base", or NULL for any | |||||||||
2457 | /// constant. Returning the expression itself is conservative. Returning a | |||||||||
2458 | /// deeper subexpression is more precise and valid as long as it isn't less | |||||||||
2459 | /// complex than another subexpression. For expressions involving multiple | |||||||||
2460 | /// unscaled values, we need to return the pointer-type SCEVUnknown. This avoids | |||||||||
2461 | /// forming chains across objects, such as: PrevOper==a[i], IVOper==b[i], | |||||||||
2462 | /// IVInc==b-a. | |||||||||
2463 | /// | |||||||||
2464 | /// Since SCEVUnknown is the rightmost type, and pointers are the rightmost | |||||||||
2465 | /// SCEVUnknown, we simply return the rightmost SCEV operand. | |||||||||
2466 | static const SCEV *getExprBase(const SCEV *S) { | |||||||||
2467 | switch (S->getSCEVType()) { | |||||||||
2468 | default: // uncluding scUnknown. | |||||||||
2469 | return S; | |||||||||
2470 | case scConstant: | |||||||||
2471 | return nullptr; | |||||||||
2472 | case scTruncate: | |||||||||
2473 | return getExprBase(cast<SCEVTruncateExpr>(S)->getOperand()); | |||||||||
2474 | case scZeroExtend: | |||||||||
2475 | return getExprBase(cast<SCEVZeroExtendExpr>(S)->getOperand()); | |||||||||
2476 | case scSignExtend: | |||||||||
2477 | return getExprBase(cast<SCEVSignExtendExpr>(S)->getOperand()); | |||||||||
2478 | case scAddExpr: { | |||||||||
2479 | // Skip over scaled operands (scMulExpr) to follow add operands as long as | |||||||||
2480 | // there's nothing more complex. | |||||||||
2481 | // FIXME: not sure if we want to recognize negation. | |||||||||
2482 | const SCEVAddExpr *Add = cast<SCEVAddExpr>(S); | |||||||||
2483 | for (std::reverse_iterator<SCEVAddExpr::op_iterator> I(Add->op_end()), | |||||||||
2484 | E(Add->op_begin()); I != E; ++I) { | |||||||||
2485 | const SCEV *SubExpr = *I; | |||||||||
2486 | if (SubExpr->getSCEVType() == scAddExpr) | |||||||||
2487 | return getExprBase(SubExpr); | |||||||||
2488 | ||||||||||
2489 | if (SubExpr->getSCEVType() != scMulExpr) | |||||||||
2490 | return SubExpr; | |||||||||
2491 | } | |||||||||
2492 | return S; // all operands are scaled, be conservative. | |||||||||
2493 | } | |||||||||
2494 | case scAddRecExpr: | |||||||||
2495 | return getExprBase(cast<SCEVAddRecExpr>(S)->getStart()); | |||||||||
2496 | } | |||||||||
2497 | } | |||||||||
2498 | ||||||||||
2499 | /// Return true if the chain increment is profitable to expand into a loop | |||||||||
2500 | /// invariant value, which may require its own register. A profitable chain | |||||||||
2501 | /// increment will be an offset relative to the same base. We allow such offsets | |||||||||
2502 | /// to potentially be used as chain increment as long as it's not obviously | |||||||||
2503 | /// expensive to expand using real instructions. | |||||||||
2504 | bool IVChain::isProfitableIncrement(const SCEV *OperExpr, | |||||||||
2505 | const SCEV *IncExpr, | |||||||||
2506 | ScalarEvolution &SE) { | |||||||||
2507 | // Aggressively form chains when -stress-ivchain. | |||||||||
2508 | if (StressIVChain) | |||||||||
2509 | return true; | |||||||||
2510 | ||||||||||
2511 | // Do not replace a constant offset from IV head with a nonconstant IV | |||||||||
2512 | // increment. | |||||||||
2513 | if (!isa<SCEVConstant>(IncExpr)) { | |||||||||
2514 | const SCEV *HeadExpr = SE.getSCEV(getWideOperand(Incs[0].IVOperand)); | |||||||||
2515 | if (isa<SCEVConstant>(SE.getMinusSCEV(OperExpr, HeadExpr))) | |||||||||
2516 | return 0; | |||||||||
2517 | } | |||||||||
2518 | ||||||||||
2519 | SmallPtrSet<const SCEV*, 8> Processed; | |||||||||
2520 | return !isHighCostExpansion(IncExpr, Processed, SE); | |||||||||
2521 | } | |||||||||
2522 | ||||||||||
2523 | /// Return true if the number of registers needed for the chain is estimated to | |||||||||
2524 | /// be less than the number required for the individual IV users. First prohibit | |||||||||
2525 | /// any IV users that keep the IV live across increments (the Users set should | |||||||||
2526 | /// be empty). Next count the number and type of increments in the chain. | |||||||||
2527 | /// | |||||||||
2528 | /// Chaining IVs can lead to considerable code bloat if ISEL doesn't | |||||||||
2529 | /// effectively use postinc addressing modes. Only consider it profitable it the | |||||||||
2530 | /// increments can be computed in fewer registers when chained. | |||||||||
2531 | /// | |||||||||
2532 | /// TODO: Consider IVInc free if it's already used in another chains. | |||||||||
2533 | static bool | |||||||||
2534 | isProfitableChain(IVChain &Chain, SmallPtrSetImpl<Instruction*> &Users, | |||||||||
2535 | ScalarEvolution &SE, const TargetTransformInfo &TTI) { | |||||||||
2536 | if (StressIVChain) | |||||||||
2537 | return true; | |||||||||
2538 | ||||||||||
2539 | if (!Chain.hasIncs()) | |||||||||
2540 | return false; | |||||||||
2541 | ||||||||||
2542 | if (!Users.empty()) { | |||||||||
2543 | DEBUG(dbgs() << "Chain: " << *Chain.Incs[0].UserInst << " users:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Chain: " << *Chain. Incs[0].UserInst << " users:\n"; for (Instruction *Inst : Users) { dbgs() << " " << *Inst << "\n" ; }; } } while (false) | |||||||||
2544 | for (Instruction *Inst : Users) {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Chain: " << *Chain. Incs[0].UserInst << " users:\n"; for (Instruction *Inst : Users) { dbgs() << " " << *Inst << "\n" ; }; } } while (false) | |||||||||
2545 | dbgs() << " " << *Inst << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Chain: " << *Chain. Incs[0].UserInst << " users:\n"; for (Instruction *Inst : Users) { dbgs() << " " << *Inst << "\n" ; }; } } while (false) | |||||||||
2546 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Chain: " << *Chain. Incs[0].UserInst << " users:\n"; for (Instruction *Inst : Users) { dbgs() << " " << *Inst << "\n" ; }; } } while (false); | |||||||||
2547 | return false; | |||||||||
2548 | } | |||||||||
2549 | assert(!Chain.Incs.empty() && "empty IV chains are not allowed")((!Chain.Incs.empty() && "empty IV chains are not allowed" ) ? static_cast<void> (0) : __assert_fail ("!Chain.Incs.empty() && \"empty IV chains are not allowed\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 2549, __PRETTY_FUNCTION__)); | |||||||||
2550 | ||||||||||
2551 | // The chain itself may require a register, so intialize cost to 1. | |||||||||
2552 | int cost = 1; | |||||||||
2553 | ||||||||||
2554 | // A complete chain likely eliminates the need for keeping the original IV in | |||||||||
2555 | // a register. LSR does not currently know how to form a complete chain unless | |||||||||
2556 | // the header phi already exists. | |||||||||
2557 | if (isa<PHINode>(Chain.tailUserInst()) | |||||||||
2558 | && SE.getSCEV(Chain.tailUserInst()) == Chain.Incs[0].IncExpr) { | |||||||||
2559 | --cost; | |||||||||
2560 | } | |||||||||
2561 | const SCEV *LastIncExpr = nullptr; | |||||||||
2562 | unsigned NumConstIncrements = 0; | |||||||||
2563 | unsigned NumVarIncrements = 0; | |||||||||
2564 | unsigned NumReusedIncrements = 0; | |||||||||
2565 | for (const IVInc &Inc : Chain) { | |||||||||
2566 | if (Inc.IncExpr->isZero()) | |||||||||
2567 | continue; | |||||||||
2568 | ||||||||||
2569 | // Incrementing by zero or some constant is neutral. We assume constants can | |||||||||
2570 | // be folded into an addressing mode or an add's immediate operand. | |||||||||
2571 | if (isa<SCEVConstant>(Inc.IncExpr)) { | |||||||||
2572 | ++NumConstIncrements; | |||||||||
2573 | continue; | |||||||||
2574 | } | |||||||||
2575 | ||||||||||
2576 | if (Inc.IncExpr == LastIncExpr) | |||||||||
2577 | ++NumReusedIncrements; | |||||||||
2578 | else | |||||||||
2579 | ++NumVarIncrements; | |||||||||
2580 | ||||||||||
2581 | LastIncExpr = Inc.IncExpr; | |||||||||
2582 | } | |||||||||
2583 | // An IV chain with a single increment is handled by LSR's postinc | |||||||||
2584 | // uses. However, a chain with multiple increments requires keeping the IV's | |||||||||
2585 | // value live longer than it needs to be if chained. | |||||||||
2586 | if (NumConstIncrements > 1) | |||||||||
2587 | --cost; | |||||||||
2588 | ||||||||||
2589 | // Materializing increment expressions in the preheader that didn't exist in | |||||||||
2590 | // the original code may cost a register. For example, sign-extended array | |||||||||
2591 | // indices can produce ridiculous increments like this: | |||||||||
2592 | // IV + ((sext i32 (2 * %s) to i64) + (-1 * (sext i32 %s to i64))) | |||||||||
2593 | cost += NumVarIncrements; | |||||||||
2594 | ||||||||||
2595 | // Reusing variable increments likely saves a register to hold the multiple of | |||||||||
2596 | // the stride. | |||||||||
2597 | cost -= NumReusedIncrements; | |||||||||
2598 | ||||||||||
2599 | DEBUG(dbgs() << "Chain: " << *Chain.Incs[0].UserInst << " Cost: " << costdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Chain: " << *Chain. Incs[0].UserInst << " Cost: " << cost << "\n" ; } } while (false) | |||||||||
2600 | << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Chain: " << *Chain. Incs[0].UserInst << " Cost: " << cost << "\n" ; } } while (false); | |||||||||
2601 | ||||||||||
2602 | return cost < 0; | |||||||||
2603 | } | |||||||||
2604 | ||||||||||
2605 | /// Add this IV user to an existing chain or make it the head of a new chain. | |||||||||
2606 | void LSRInstance::ChainInstruction(Instruction *UserInst, Instruction *IVOper, | |||||||||
2607 | SmallVectorImpl<ChainUsers> &ChainUsersVec) { | |||||||||
2608 | // When IVs are used as types of varying widths, they are generally converted | |||||||||
2609 | // to a wider type with some uses remaining narrow under a (free) trunc. | |||||||||
2610 | Value *const NextIV = getWideOperand(IVOper); | |||||||||
2611 | const SCEV *const OperExpr = SE.getSCEV(NextIV); | |||||||||
2612 | const SCEV *const OperExprBase = getExprBase(OperExpr); | |||||||||
2613 | ||||||||||
2614 | // Visit all existing chains. Check if its IVOper can be computed as a | |||||||||
2615 | // profitable loop invariant increment from the last link in the Chain. | |||||||||
2616 | unsigned ChainIdx = 0, NChains = IVChainVec.size(); | |||||||||
2617 | const SCEV *LastIncExpr = nullptr; | |||||||||
2618 | for (; ChainIdx < NChains; ++ChainIdx) { | |||||||||
2619 | IVChain &Chain = IVChainVec[ChainIdx]; | |||||||||
2620 | ||||||||||
2621 | // Prune the solution space aggressively by checking that both IV operands | |||||||||
2622 | // are expressions that operate on the same unscaled SCEVUnknown. This | |||||||||
2623 | // "base" will be canceled by the subsequent getMinusSCEV call. Checking | |||||||||
2624 | // first avoids creating extra SCEV expressions. | |||||||||
2625 | if (!StressIVChain && Chain.ExprBase != OperExprBase) | |||||||||
2626 | continue; | |||||||||
2627 | ||||||||||
2628 | Value *PrevIV = getWideOperand(Chain.Incs.back().IVOperand); | |||||||||
2629 | if (!isCompatibleIVType(PrevIV, NextIV)) | |||||||||
2630 | continue; | |||||||||
2631 | ||||||||||
2632 | // A phi node terminates a chain. | |||||||||
2633 | if (isa<PHINode>(UserInst) && isa<PHINode>(Chain.tailUserInst())) | |||||||||
2634 | continue; | |||||||||
2635 | ||||||||||
2636 | // The increment must be loop-invariant so it can be kept in a register. | |||||||||
2637 | const SCEV *PrevExpr = SE.getSCEV(PrevIV); | |||||||||
2638 | const SCEV *IncExpr = SE.getMinusSCEV(OperExpr, PrevExpr); | |||||||||
2639 | if (!SE.isLoopInvariant(IncExpr, L)) | |||||||||
2640 | continue; | |||||||||
2641 | ||||||||||
2642 | if (Chain.isProfitableIncrement(OperExpr, IncExpr, SE)) { | |||||||||
2643 | LastIncExpr = IncExpr; | |||||||||
2644 | break; | |||||||||
2645 | } | |||||||||
2646 | } | |||||||||
2647 | // If we haven't found a chain, create a new one, unless we hit the max. Don't | |||||||||
2648 | // bother for phi nodes, because they must be last in the chain. | |||||||||
2649 | if (ChainIdx == NChains) { | |||||||||
2650 | if (isa<PHINode>(UserInst)) | |||||||||
2651 | return; | |||||||||
2652 | if (NChains >= MaxChains && !StressIVChain) { | |||||||||
2653 | DEBUG(dbgs() << "IV Chain Limit\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "IV Chain Limit\n"; } } while (false); | |||||||||
2654 | return; | |||||||||
2655 | } | |||||||||
2656 | LastIncExpr = OperExpr; | |||||||||
2657 | // IVUsers may have skipped over sign/zero extensions. We don't currently | |||||||||
2658 | // attempt to form chains involving extensions unless they can be hoisted | |||||||||
2659 | // into this loop's AddRec. | |||||||||
2660 | if (!isa<SCEVAddRecExpr>(LastIncExpr)) | |||||||||
2661 | return; | |||||||||
2662 | ++NChains; | |||||||||
2663 | IVChainVec.push_back(IVChain(IVInc(UserInst, IVOper, LastIncExpr), | |||||||||
2664 | OperExprBase)); | |||||||||
2665 | ChainUsersVec.resize(NChains); | |||||||||
2666 | DEBUG(dbgs() << "IV Chain#" << ChainIdx << " Head: (" << *UserInstdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx << " Head: (" << *UserInst << ") IV=" << *LastIncExpr << "\n"; } } while (false) | |||||||||
2667 | << ") IV=" << *LastIncExpr << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx << " Head: (" << *UserInst << ") IV=" << *LastIncExpr << "\n"; } } while (false); | |||||||||
2668 | } else { | |||||||||
2669 | DEBUG(dbgs() << "IV Chain#" << ChainIdx << " Inc: (" << *UserInstdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx << " Inc: (" << *UserInst << ") IV+" << *LastIncExpr << "\n"; } } while (false) | |||||||||
2670 | << ") IV+" << *LastIncExpr << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx << " Inc: (" << *UserInst << ") IV+" << *LastIncExpr << "\n"; } } while (false); | |||||||||
2671 | // Add this IV user to the end of the chain. | |||||||||
2672 | IVChainVec[ChainIdx].add(IVInc(UserInst, IVOper, LastIncExpr)); | |||||||||
2673 | } | |||||||||
2674 | IVChain &Chain = IVChainVec[ChainIdx]; | |||||||||
2675 | ||||||||||
2676 | SmallPtrSet<Instruction*,4> &NearUsers = ChainUsersVec[ChainIdx].NearUsers; | |||||||||
2677 | // This chain's NearUsers become FarUsers. | |||||||||
2678 | if (!LastIncExpr->isZero()) { | |||||||||
2679 | ChainUsersVec[ChainIdx].FarUsers.insert(NearUsers.begin(), | |||||||||
2680 | NearUsers.end()); | |||||||||
2681 | NearUsers.clear(); | |||||||||
2682 | } | |||||||||
2683 | ||||||||||
2684 | // All other uses of IVOperand become near uses of the chain. | |||||||||
2685 | // We currently ignore intermediate values within SCEV expressions, assuming | |||||||||
2686 | // they will eventually be used be the current chain, or can be computed | |||||||||
2687 | // from one of the chain increments. To be more precise we could | |||||||||
2688 | // transitively follow its user and only add leaf IV users to the set. | |||||||||
2689 | for (User *U : IVOper->users()) { | |||||||||
2690 | Instruction *OtherUse = dyn_cast<Instruction>(U); | |||||||||
2691 | if (!OtherUse) | |||||||||
2692 | continue; | |||||||||
2693 | // Uses in the chain will no longer be uses if the chain is formed. | |||||||||
2694 | // Include the head of the chain in this iteration (not Chain.begin()). | |||||||||
2695 | IVChain::const_iterator IncIter = Chain.Incs.begin(); | |||||||||
2696 | IVChain::const_iterator IncEnd = Chain.Incs.end(); | |||||||||
2697 | for( ; IncIter != IncEnd; ++IncIter) { | |||||||||
2698 | if (IncIter->UserInst == OtherUse) | |||||||||
2699 | break; | |||||||||
2700 | } | |||||||||
2701 | if (IncIter != IncEnd) | |||||||||
2702 | continue; | |||||||||
2703 | ||||||||||
2704 | if (SE.isSCEVable(OtherUse->getType()) | |||||||||
2705 | && !isa<SCEVUnknown>(SE.getSCEV(OtherUse)) | |||||||||
2706 | && IU.isIVUserOrOperand(OtherUse)) { | |||||||||
2707 | continue; | |||||||||
2708 | } | |||||||||
2709 | NearUsers.insert(OtherUse); | |||||||||
2710 | } | |||||||||
2711 | ||||||||||
2712 | // Since this user is part of the chain, it's no longer considered a use | |||||||||
2713 | // of the chain. | |||||||||
2714 | ChainUsersVec[ChainIdx].FarUsers.erase(UserInst); | |||||||||
2715 | } | |||||||||
2716 | ||||||||||
2717 | /// Populate the vector of Chains. | |||||||||
2718 | /// | |||||||||
2719 | /// This decreases ILP at the architecture level. Targets with ample registers, | |||||||||
2720 | /// multiple memory ports, and no register renaming probably don't want | |||||||||
2721 | /// this. However, such targets should probably disable LSR altogether. | |||||||||
2722 | /// | |||||||||
2723 | /// The job of LSR is to make a reasonable choice of induction variables across | |||||||||
2724 | /// the loop. Subsequent passes can easily "unchain" computation exposing more | |||||||||
2725 | /// ILP *within the loop* if the target wants it. | |||||||||
2726 | /// | |||||||||
2727 | /// Finding the best IV chain is potentially a scheduling problem. Since LSR | |||||||||
2728 | /// will not reorder memory operations, it will recognize this as a chain, but | |||||||||
2729 | /// will generate redundant IV increments. Ideally this would be corrected later | |||||||||
2730 | /// by a smart scheduler: | |||||||||
2731 | /// = A[i] | |||||||||
2732 | /// = A[i+x] | |||||||||
2733 | /// A[i] = | |||||||||
2734 | /// A[i+x] = | |||||||||
2735 | /// | |||||||||
2736 | /// TODO: Walk the entire domtree within this loop, not just the path to the | |||||||||
2737 | /// loop latch. This will discover chains on side paths, but requires | |||||||||
2738 | /// maintaining multiple copies of the Chains state. | |||||||||
2739 | void LSRInstance::CollectChains() { | |||||||||
2740 | DEBUG(dbgs() << "Collecting IV Chains.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Collecting IV Chains.\n"; } } while (false); | |||||||||
2741 | SmallVector<ChainUsers, 8> ChainUsersVec; | |||||||||
2742 | ||||||||||
2743 | SmallVector<BasicBlock *,8> LatchPath; | |||||||||
2744 | BasicBlock *LoopHeader = L->getHeader(); | |||||||||
2745 | for (DomTreeNode *Rung = DT.getNode(L->getLoopLatch()); | |||||||||
2746 | Rung->getBlock() != LoopHeader; Rung = Rung->getIDom()) { | |||||||||
2747 | LatchPath.push_back(Rung->getBlock()); | |||||||||
2748 | } | |||||||||
2749 | LatchPath.push_back(LoopHeader); | |||||||||
2750 | ||||||||||
2751 | // Walk the instruction stream from the loop header to the loop latch. | |||||||||
2752 | for (BasicBlock *BB : reverse(LatchPath)) { | |||||||||
2753 | for (Instruction &I : *BB) { | |||||||||
2754 | // Skip instructions that weren't seen by IVUsers analysis. | |||||||||
2755 | if (isa<PHINode>(I) || !IU.isIVUserOrOperand(&I)) | |||||||||
2756 | continue; | |||||||||
2757 | ||||||||||
2758 | // Ignore users that are part of a SCEV expression. This way we only | |||||||||
2759 | // consider leaf IV Users. This effectively rediscovers a portion of | |||||||||
2760 | // IVUsers analysis but in program order this time. | |||||||||
2761 | if (SE.isSCEVable(I.getType()) && !isa<SCEVUnknown>(SE.getSCEV(&I))) | |||||||||
2762 | continue; | |||||||||
2763 | ||||||||||
2764 | // Remove this instruction from any NearUsers set it may be in. | |||||||||
2765 | for (unsigned ChainIdx = 0, NChains = IVChainVec.size(); | |||||||||
2766 | ChainIdx < NChains; ++ChainIdx) { | |||||||||
2767 | ChainUsersVec[ChainIdx].NearUsers.erase(&I); | |||||||||
2768 | } | |||||||||
2769 | // Search for operands that can be chained. | |||||||||
2770 | SmallPtrSet<Instruction*, 4> UniqueOperands; | |||||||||
2771 | User::op_iterator IVOpEnd = I.op_end(); | |||||||||
2772 | User::op_iterator IVOpIter = findIVOperand(I.op_begin(), IVOpEnd, L, SE); | |||||||||
2773 | while (IVOpIter != IVOpEnd) { | |||||||||
2774 | Instruction *IVOpInst = cast<Instruction>(*IVOpIter); | |||||||||
2775 | if (UniqueOperands.insert(IVOpInst).second) | |||||||||
2776 | ChainInstruction(&I, IVOpInst, ChainUsersVec); | |||||||||
2777 | IVOpIter = findIVOperand(std::next(IVOpIter), IVOpEnd, L, SE); | |||||||||
2778 | } | |||||||||
2779 | } // Continue walking down the instructions. | |||||||||
2780 | } // Continue walking down the domtree. | |||||||||
2781 | // Visit phi backedges to determine if the chain can generate the IV postinc. | |||||||||
2782 | for (BasicBlock::iterator I = L->getHeader()->begin(); | |||||||||
2783 | PHINode *PN = dyn_cast<PHINode>(I); ++I) { | |||||||||
2784 | if (!SE.isSCEVable(PN->getType())) | |||||||||
2785 | continue; | |||||||||
2786 | ||||||||||
2787 | Instruction *IncV = | |||||||||
2788 | dyn_cast<Instruction>(PN->getIncomingValueForBlock(L->getLoopLatch())); | |||||||||
2789 | if (IncV) | |||||||||
2790 | ChainInstruction(PN, IncV, ChainUsersVec); | |||||||||
2791 | } | |||||||||
2792 | // Remove any unprofitable chains. | |||||||||
2793 | unsigned ChainIdx = 0; | |||||||||
2794 | for (unsigned UsersIdx = 0, NChains = IVChainVec.size(); | |||||||||
2795 | UsersIdx < NChains; ++UsersIdx) { | |||||||||
2796 | if (!isProfitableChain(IVChainVec[UsersIdx], | |||||||||
2797 | ChainUsersVec[UsersIdx].FarUsers, SE, TTI)) | |||||||||
2798 | continue; | |||||||||
2799 | // Preserve the chain at UsesIdx. | |||||||||
2800 | if (ChainIdx != UsersIdx) | |||||||||
2801 | IVChainVec[ChainIdx] = IVChainVec[UsersIdx]; | |||||||||
2802 | FinalizeChain(IVChainVec[ChainIdx]); | |||||||||
2803 | ++ChainIdx; | |||||||||
2804 | } | |||||||||
2805 | IVChainVec.resize(ChainIdx); | |||||||||
2806 | } | |||||||||
2807 | ||||||||||
2808 | void LSRInstance::FinalizeChain(IVChain &Chain) { | |||||||||
2809 | assert(!Chain.Incs.empty() && "empty IV chains are not allowed")((!Chain.Incs.empty() && "empty IV chains are not allowed" ) ? static_cast<void> (0) : __assert_fail ("!Chain.Incs.empty() && \"empty IV chains are not allowed\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 2809, __PRETTY_FUNCTION__)); | |||||||||
2810 | DEBUG(dbgs() << "Final Chain: " << *Chain.Incs[0].UserInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Final Chain: " << * Chain.Incs[0].UserInst << "\n"; } } while (false); | |||||||||
2811 | ||||||||||
2812 | for (const IVInc &Inc : Chain) { | |||||||||
2813 | DEBUG(dbgs() << " Inc: " << Inc.UserInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Inc: " << Inc .UserInst << "\n"; } } while (false); | |||||||||
2814 | auto UseI = find(Inc.UserInst->operands(), Inc.IVOperand); | |||||||||
2815 | assert(UseI != Inc.UserInst->op_end() && "cannot find IV operand")((UseI != Inc.UserInst->op_end() && "cannot find IV operand" ) ? static_cast<void> (0) : __assert_fail ("UseI != Inc.UserInst->op_end() && \"cannot find IV operand\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 2815, __PRETTY_FUNCTION__)); | |||||||||
2816 | IVIncSet.insert(UseI); | |||||||||
2817 | } | |||||||||
2818 | } | |||||||||
2819 | ||||||||||
2820 | /// Return true if the IVInc can be folded into an addressing mode. | |||||||||
2821 | static bool canFoldIVIncExpr(const SCEV *IncExpr, Instruction *UserInst, | |||||||||
2822 | Value *Operand, const TargetTransformInfo &TTI) { | |||||||||
2823 | const SCEVConstant *IncConst = dyn_cast<SCEVConstant>(IncExpr); | |||||||||
2824 | if (!IncConst || !isAddressUse(UserInst, Operand)) | |||||||||
2825 | return false; | |||||||||
2826 | ||||||||||
2827 | if (IncConst->getAPInt().getMinSignedBits() > 64) | |||||||||
2828 | return false; | |||||||||
2829 | ||||||||||
2830 | MemAccessTy AccessTy = getAccessType(UserInst); | |||||||||
2831 | int64_t IncOffset = IncConst->getValue()->getSExtValue(); | |||||||||
2832 | if (!isAlwaysFoldable(TTI, LSRUse::Address, AccessTy, /*BaseGV=*/nullptr, | |||||||||
2833 | IncOffset, /*HaseBaseReg=*/false)) | |||||||||
2834 | return false; | |||||||||
2835 | ||||||||||
2836 | return true; | |||||||||
2837 | } | |||||||||
2838 | ||||||||||
2839 | /// Generate an add or subtract for each IVInc in a chain to materialize the IV | |||||||||
2840 | /// user's operand from the previous IV user's operand. | |||||||||
2841 | void LSRInstance::GenerateIVChain(const IVChain &Chain, SCEVExpander &Rewriter, | |||||||||
2842 | SmallVectorImpl<WeakVH> &DeadInsts) { | |||||||||
2843 | // Find the new IVOperand for the head of the chain. It may have been replaced | |||||||||
2844 | // by LSR. | |||||||||
2845 | const IVInc &Head = Chain.Incs[0]; | |||||||||
2846 | User::op_iterator IVOpEnd = Head.UserInst->op_end(); | |||||||||
2847 | // findIVOperand returns IVOpEnd if it can no longer find a valid IV user. | |||||||||
2848 | User::op_iterator IVOpIter = findIVOperand(Head.UserInst->op_begin(), | |||||||||
2849 | IVOpEnd, L, SE); | |||||||||
2850 | Value *IVSrc = nullptr; | |||||||||
2851 | while (IVOpIter != IVOpEnd) { | |||||||||
2852 | IVSrc = getWideOperand(*IVOpIter); | |||||||||
2853 | ||||||||||
2854 | // If this operand computes the expression that the chain needs, we may use | |||||||||
2855 | // it. (Check this after setting IVSrc which is used below.) | |||||||||
2856 | // | |||||||||
2857 | // Note that if Head.IncExpr is wider than IVSrc, then this phi is too | |||||||||
2858 | // narrow for the chain, so we can no longer use it. We do allow using a | |||||||||
2859 | // wider phi, assuming the LSR checked for free truncation. In that case we | |||||||||
2860 | // should already have a truncate on this operand such that | |||||||||
2861 | // getSCEV(IVSrc) == IncExpr. | |||||||||
2862 | if (SE.getSCEV(*IVOpIter) == Head.IncExpr | |||||||||
2863 | || SE.getSCEV(IVSrc) == Head.IncExpr) { | |||||||||
2864 | break; | |||||||||
2865 | } | |||||||||
2866 | IVOpIter = findIVOperand(std::next(IVOpIter), IVOpEnd, L, SE); | |||||||||
2867 | } | |||||||||
2868 | if (IVOpIter == IVOpEnd) { | |||||||||
2869 | // Gracefully give up on this chain. | |||||||||
2870 | DEBUG(dbgs() << "Concealed chain head: " << *Head.UserInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Concealed chain head: " << *Head.UserInst << "\n"; } } while (false); | |||||||||
2871 | return; | |||||||||
2872 | } | |||||||||
2873 | ||||||||||
2874 | DEBUG(dbgs() << "Generate chain at: " << *IVSrc << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Generate chain at: " << *IVSrc << "\n"; } } while (false); | |||||||||
2875 | Type *IVTy = IVSrc->getType(); | |||||||||
2876 | Type *IntTy = SE.getEffectiveSCEVType(IVTy); | |||||||||
2877 | const SCEV *LeftOverExpr = nullptr; | |||||||||
2878 | for (const IVInc &Inc : Chain) { | |||||||||
2879 | Instruction *InsertPt = Inc.UserInst; | |||||||||
2880 | if (isa<PHINode>(InsertPt)) | |||||||||
2881 | InsertPt = L->getLoopLatch()->getTerminator(); | |||||||||
2882 | ||||||||||
2883 | // IVOper will replace the current IV User's operand. IVSrc is the IV | |||||||||
2884 | // value currently held in a register. | |||||||||
2885 | Value *IVOper = IVSrc; | |||||||||
2886 | if (!Inc.IncExpr->isZero()) { | |||||||||
2887 | // IncExpr was the result of subtraction of two narrow values, so must | |||||||||
2888 | // be signed. | |||||||||
2889 | const SCEV *IncExpr = SE.getNoopOrSignExtend(Inc.IncExpr, IntTy); | |||||||||
2890 | LeftOverExpr = LeftOverExpr ? | |||||||||
2891 | SE.getAddExpr(LeftOverExpr, IncExpr) : IncExpr; | |||||||||
2892 | } | |||||||||
2893 | if (LeftOverExpr && !LeftOverExpr->isZero()) { | |||||||||
2894 | // Expand the IV increment. | |||||||||
2895 | Rewriter.clearPostInc(); | |||||||||
2896 | Value *IncV = Rewriter.expandCodeFor(LeftOverExpr, IntTy, InsertPt); | |||||||||
2897 | const SCEV *IVOperExpr = SE.getAddExpr(SE.getUnknown(IVSrc), | |||||||||
2898 | SE.getUnknown(IncV)); | |||||||||
2899 | IVOper = Rewriter.expandCodeFor(IVOperExpr, IVTy, InsertPt); | |||||||||
2900 | ||||||||||
2901 | // If an IV increment can't be folded, use it as the next IV value. | |||||||||
2902 | if (!canFoldIVIncExpr(LeftOverExpr, Inc.UserInst, Inc.IVOperand, TTI)) { | |||||||||
2903 | assert(IVTy == IVOper->getType() && "inconsistent IV increment type")((IVTy == IVOper->getType() && "inconsistent IV increment type" ) ? static_cast<void> (0) : __assert_fail ("IVTy == IVOper->getType() && \"inconsistent IV increment type\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 2903, __PRETTY_FUNCTION__)); | |||||||||
2904 | IVSrc = IVOper; | |||||||||
2905 | LeftOverExpr = nullptr; | |||||||||
2906 | } | |||||||||
2907 | } | |||||||||
2908 | Type *OperTy = Inc.IVOperand->getType(); | |||||||||
2909 | if (IVTy != OperTy) { | |||||||||
2910 | assert(SE.getTypeSizeInBits(IVTy) >= SE.getTypeSizeInBits(OperTy) &&((SE.getTypeSizeInBits(IVTy) >= SE.getTypeSizeInBits(OperTy ) && "cannot extend a chained IV") ? static_cast<void > (0) : __assert_fail ("SE.getTypeSizeInBits(IVTy) >= SE.getTypeSizeInBits(OperTy) && \"cannot extend a chained IV\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 2911, __PRETTY_FUNCTION__)) | |||||||||
2911 | "cannot extend a chained IV")((SE.getTypeSizeInBits(IVTy) >= SE.getTypeSizeInBits(OperTy ) && "cannot extend a chained IV") ? static_cast<void > (0) : __assert_fail ("SE.getTypeSizeInBits(IVTy) >= SE.getTypeSizeInBits(OperTy) && \"cannot extend a chained IV\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 2911, __PRETTY_FUNCTION__)); | |||||||||
2912 | IRBuilder<> Builder(InsertPt); | |||||||||
2913 | IVOper = Builder.CreateTruncOrBitCast(IVOper, OperTy, "lsr.chain"); | |||||||||
2914 | } | |||||||||
2915 | Inc.UserInst->replaceUsesOfWith(Inc.IVOperand, IVOper); | |||||||||
2916 | DeadInsts.emplace_back(Inc.IVOperand); | |||||||||
2917 | } | |||||||||
2918 | // If LSR created a new, wider phi, we may also replace its postinc. We only | |||||||||
2919 | // do this if we also found a wide value for the head of the chain. | |||||||||
2920 | if (isa<PHINode>(Chain.tailUserInst())) { | |||||||||
2921 | for (BasicBlock::iterator I = L->getHeader()->begin(); | |||||||||
2922 | PHINode *Phi = dyn_cast<PHINode>(I); ++I) { | |||||||||
2923 | if (!isCompatibleIVType(Phi, IVSrc)) | |||||||||
2924 | continue; | |||||||||
2925 | Instruction *PostIncV = dyn_cast<Instruction>( | |||||||||
2926 | Phi->getIncomingValueForBlock(L->getLoopLatch())); | |||||||||
2927 | if (!PostIncV || (SE.getSCEV(PostIncV) != SE.getSCEV(IVSrc))) | |||||||||
2928 | continue; | |||||||||
2929 | Value *IVOper = IVSrc; | |||||||||
2930 | Type *PostIncTy = PostIncV->getType(); | |||||||||
2931 | if (IVTy != PostIncTy) { | |||||||||
2932 | assert(PostIncTy->isPointerTy() && "mixing int/ptr IV types")((PostIncTy->isPointerTy() && "mixing int/ptr IV types" ) ? static_cast<void> (0) : __assert_fail ("PostIncTy->isPointerTy() && \"mixing int/ptr IV types\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 2932, __PRETTY_FUNCTION__)); | |||||||||
2933 | IRBuilder<> Builder(L->getLoopLatch()->getTerminator()); | |||||||||
2934 | Builder.SetCurrentDebugLocation(PostIncV->getDebugLoc()); | |||||||||
2935 | IVOper = Builder.CreatePointerCast(IVSrc, PostIncTy, "lsr.chain"); | |||||||||
2936 | } | |||||||||
2937 | Phi->replaceUsesOfWith(PostIncV, IVOper); | |||||||||
2938 | DeadInsts.emplace_back(PostIncV); | |||||||||
2939 | } | |||||||||
2940 | } | |||||||||
2941 | } | |||||||||
2942 | ||||||||||
2943 | void LSRInstance::CollectFixupsAndInitialFormulae() { | |||||||||
2944 | for (const IVStrideUse &U : IU) { | |||||||||
2945 | Instruction *UserInst = U.getUser(); | |||||||||
2946 | // Skip IV users that are part of profitable IV Chains. | |||||||||
2947 | User::op_iterator UseI = | |||||||||
2948 | find(UserInst->operands(), U.getOperandValToReplace()); | |||||||||
2949 | assert(UseI != UserInst->op_end() && "cannot find IV operand")((UseI != UserInst->op_end() && "cannot find IV operand" ) ? static_cast<void> (0) : __assert_fail ("UseI != UserInst->op_end() && \"cannot find IV operand\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 2949, __PRETTY_FUNCTION__)); | |||||||||
2950 | if (IVIncSet.count(UseI)) | |||||||||
2951 | continue; | |||||||||
2952 | ||||||||||
2953 | LSRUse::KindType Kind = LSRUse::Basic; | |||||||||
2954 | MemAccessTy AccessTy; | |||||||||
2955 | if (isAddressUse(UserInst, U.getOperandValToReplace())) { | |||||||||
2956 | Kind = LSRUse::Address; | |||||||||
2957 | AccessTy = getAccessType(UserInst); | |||||||||
2958 | } | |||||||||
2959 | ||||||||||
2960 | const SCEV *S = IU.getExpr(U); | |||||||||
2961 | PostIncLoopSet TmpPostIncLoops = U.getPostIncLoops(); | |||||||||
2962 | ||||||||||
2963 | // Equality (== and !=) ICmps are special. We can rewrite (i == N) as | |||||||||
2964 | // (N - i == 0), and this allows (N - i) to be the expression that we work | |||||||||
2965 | // with rather than just N or i, so we can consider the register | |||||||||
2966 | // requirements for both N and i at the same time. Limiting this code to | |||||||||
2967 | // equality icmps is not a problem because all interesting loops use | |||||||||
2968 | // equality icmps, thanks to IndVarSimplify. | |||||||||
2969 | if (ICmpInst *CI = dyn_cast<ICmpInst>(UserInst)) | |||||||||
2970 | if (CI->isEquality()) { | |||||||||
2971 | // Swap the operands if needed to put the OperandValToReplace on the | |||||||||
2972 | // left, for consistency. | |||||||||
2973 | Value *NV = CI->getOperand(1); | |||||||||
2974 | if (NV == U.getOperandValToReplace()) { | |||||||||
2975 | CI->setOperand(1, CI->getOperand(0)); | |||||||||
2976 | CI->setOperand(0, NV); | |||||||||
2977 | NV = CI->getOperand(1); | |||||||||
2978 | Changed = true; | |||||||||
2979 | } | |||||||||
2980 | ||||||||||
2981 | // x == y --> x - y == 0 | |||||||||
2982 | const SCEV *N = SE.getSCEV(NV); | |||||||||
2983 | if (SE.isLoopInvariant(N, L) && isSafeToExpand(N, SE)) { | |||||||||
2984 | // S is normalized, so normalize N before folding it into S | |||||||||
2985 | // to keep the result normalized. | |||||||||
2986 | N = TransformForPostIncUse(Normalize, N, CI, nullptr, | |||||||||
2987 | TmpPostIncLoops, SE, DT); | |||||||||
2988 | Kind = LSRUse::ICmpZero; | |||||||||
2989 | S = SE.getMinusSCEV(N, S); | |||||||||
2990 | } | |||||||||
2991 | ||||||||||
2992 | // -1 and the negations of all interesting strides (except the negation | |||||||||
2993 | // of -1) are now also interesting. | |||||||||
2994 | for (size_t i = 0, e = Factors.size(); i != e; ++i) | |||||||||
2995 | if (Factors[i] != -1) | |||||||||
2996 | Factors.insert(-(uint64_t)Factors[i]); | |||||||||
2997 | Factors.insert(-1); | |||||||||
2998 | } | |||||||||
2999 | ||||||||||
3000 | // Get or create an LSRUse. | |||||||||
3001 | std::pair<size_t, int64_t> P = getUse(S, Kind, AccessTy); | |||||||||
3002 | size_t LUIdx = P.first; | |||||||||
3003 | int64_t Offset = P.second; | |||||||||
3004 | LSRUse &LU = Uses[LUIdx]; | |||||||||
3005 | ||||||||||
3006 | // Record the fixup. | |||||||||
3007 | LSRFixup &LF = LU.getNewFixup(); | |||||||||
3008 | LF.UserInst = UserInst; | |||||||||
3009 | LF.OperandValToReplace = U.getOperandValToReplace(); | |||||||||
3010 | LF.PostIncLoops = TmpPostIncLoops; | |||||||||
3011 | LF.Offset = Offset; | |||||||||
3012 | LU.AllFixupsOutsideLoop &= LF.isUseFullyOutsideLoop(L); | |||||||||
3013 | ||||||||||
3014 | if (!LU.WidestFixupType || | |||||||||
3015 | SE.getTypeSizeInBits(LU.WidestFixupType) < | |||||||||
3016 | SE.getTypeSizeInBits(LF.OperandValToReplace->getType())) | |||||||||
3017 | LU.WidestFixupType = LF.OperandValToReplace->getType(); | |||||||||
3018 | ||||||||||
3019 | // If this is the first use of this LSRUse, give it a formula. | |||||||||
3020 | if (LU.Formulae.empty()) { | |||||||||
3021 | InsertInitialFormula(S, LU, LUIdx); | |||||||||
3022 | CountRegisters(LU.Formulae.back(), LUIdx); | |||||||||
3023 | } | |||||||||
3024 | } | |||||||||
3025 | ||||||||||
3026 | DEBUG(print_fixups(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { print_fixups(dbgs()); } } while (false); | |||||||||
3027 | } | |||||||||
3028 | ||||||||||
3029 | /// Insert a formula for the given expression into the given use, separating out | |||||||||
3030 | /// loop-variant portions from loop-invariant and loop-computable portions. | |||||||||
3031 | void | |||||||||
3032 | LSRInstance::InsertInitialFormula(const SCEV *S, LSRUse &LU, size_t LUIdx) { | |||||||||
3033 | // Mark uses whose expressions cannot be expanded. | |||||||||
3034 | if (!isSafeToExpand(S, SE)) | |||||||||
3035 | LU.RigidFormula = true; | |||||||||
3036 | ||||||||||
3037 | Formula F; | |||||||||
3038 | F.initialMatch(S, L, SE); | |||||||||
3039 | bool Inserted = InsertFormula(LU, LUIdx, F); | |||||||||
3040 | assert(Inserted && "Initial formula already exists!")((Inserted && "Initial formula already exists!") ? static_cast <void> (0) : __assert_fail ("Inserted && \"Initial formula already exists!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3040, __PRETTY_FUNCTION__)); (void)Inserted; | |||||||||
3041 | } | |||||||||
3042 | ||||||||||
3043 | /// Insert a simple single-register formula for the given expression into the | |||||||||
3044 | /// given use. | |||||||||
3045 | void | |||||||||
3046 | LSRInstance::InsertSupplementalFormula(const SCEV *S, | |||||||||
3047 | LSRUse &LU, size_t LUIdx) { | |||||||||
3048 | Formula F; | |||||||||
3049 | F.BaseRegs.push_back(S); | |||||||||
3050 | F.HasBaseReg = true; | |||||||||
3051 | bool Inserted = InsertFormula(LU, LUIdx, F); | |||||||||
3052 | assert(Inserted && "Supplemental formula already exists!")((Inserted && "Supplemental formula already exists!") ? static_cast<void> (0) : __assert_fail ("Inserted && \"Supplemental formula already exists!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3052, __PRETTY_FUNCTION__)); (void)Inserted; | |||||||||
3053 | } | |||||||||
3054 | ||||||||||
3055 | /// Note which registers are used by the given formula, updating RegUses. | |||||||||
3056 | void LSRInstance::CountRegisters(const Formula &F, size_t LUIdx) { | |||||||||
3057 | if (F.ScaledReg) | |||||||||
3058 | RegUses.countRegister(F.ScaledReg, LUIdx); | |||||||||
3059 | for (const SCEV *BaseReg : F.BaseRegs) | |||||||||
3060 | RegUses.countRegister(BaseReg, LUIdx); | |||||||||
3061 | } | |||||||||
3062 | ||||||||||
3063 | /// If the given formula has not yet been inserted, add it to the list, and | |||||||||
3064 | /// return true. Return false otherwise. | |||||||||
3065 | bool LSRInstance::InsertFormula(LSRUse &LU, unsigned LUIdx, const Formula &F) { | |||||||||
3066 | // Do not insert formula that we will not be able to expand. | |||||||||
3067 | assert(isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) &&((isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy , F) && "Formula is illegal") ? static_cast<void> (0) : __assert_fail ("isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) && \"Formula is illegal\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3068, __PRETTY_FUNCTION__)) | |||||||||
3068 | "Formula is illegal")((isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy , F) && "Formula is illegal") ? static_cast<void> (0) : __assert_fail ("isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) && \"Formula is illegal\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3068, __PRETTY_FUNCTION__)); | |||||||||
3069 | if (!LU.InsertFormula(F)) | |||||||||
3070 | return false; | |||||||||
3071 | ||||||||||
3072 | CountRegisters(F, LUIdx); | |||||||||
3073 | return true; | |||||||||
3074 | } | |||||||||
3075 | ||||||||||
3076 | /// Check for other uses of loop-invariant values which we're tracking. These | |||||||||
3077 | /// other uses will pin these values in registers, making them less profitable | |||||||||
3078 | /// for elimination. | |||||||||
3079 | /// TODO: This currently misses non-constant addrec step registers. | |||||||||
3080 | /// TODO: Should this give more weight to users inside the loop? | |||||||||
3081 | void | |||||||||
3082 | LSRInstance::CollectLoopInvariantFixupsAndFormulae() { | |||||||||
3083 | SmallVector<const SCEV *, 8> Worklist(RegUses.begin(), RegUses.end()); | |||||||||
3084 | SmallPtrSet<const SCEV *, 32> Visited; | |||||||||
3085 | ||||||||||
3086 | while (!Worklist.empty()) { | |||||||||
3087 | const SCEV *S = Worklist.pop_back_val(); | |||||||||
3088 | ||||||||||
3089 | // Don't process the same SCEV twice | |||||||||
3090 | if (!Visited.insert(S).second) | |||||||||
3091 | continue; | |||||||||
3092 | ||||||||||
3093 | if (const SCEVNAryExpr *N = dyn_cast<SCEVNAryExpr>(S)) | |||||||||
3094 | Worklist.append(N->op_begin(), N->op_end()); | |||||||||
3095 | else if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(S)) | |||||||||
3096 | Worklist.push_back(C->getOperand()); | |||||||||
3097 | else if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) { | |||||||||
3098 | Worklist.push_back(D->getLHS()); | |||||||||
3099 | Worklist.push_back(D->getRHS()); | |||||||||
3100 | } else if (const SCEVUnknown *US = dyn_cast<SCEVUnknown>(S)) { | |||||||||
3101 | const Value *V = US->getValue(); | |||||||||
3102 | if (const Instruction *Inst = dyn_cast<Instruction>(V)) { | |||||||||
3103 | // Look for instructions defined outside the loop. | |||||||||
3104 | if (L->contains(Inst)) continue; | |||||||||
3105 | } else if (isa<UndefValue>(V)) | |||||||||
3106 | // Undef doesn't have a live range, so it doesn't matter. | |||||||||
3107 | continue; | |||||||||
3108 | for (const Use &U : V->uses()) { | |||||||||
3109 | const Instruction *UserInst = dyn_cast<Instruction>(U.getUser()); | |||||||||
3110 | // Ignore non-instructions. | |||||||||
3111 | if (!UserInst) | |||||||||
3112 | continue; | |||||||||
3113 | // Ignore instructions in other functions (as can happen with | |||||||||
3114 | // Constants). | |||||||||
3115 | if (UserInst->getParent()->getParent() != L->getHeader()->getParent()) | |||||||||
3116 | continue; | |||||||||
3117 | // Ignore instructions not dominated by the loop. | |||||||||
3118 | const BasicBlock *UseBB = !isa<PHINode>(UserInst) ? | |||||||||
3119 | UserInst->getParent() : | |||||||||
3120 | cast<PHINode>(UserInst)->getIncomingBlock( | |||||||||
3121 | PHINode::getIncomingValueNumForOperand(U.getOperandNo())); | |||||||||
3122 | if (!DT.dominates(L->getHeader(), UseBB)) | |||||||||
3123 | continue; | |||||||||
3124 | // Don't bother if the instruction is in a BB which ends in an EHPad. | |||||||||
3125 | if (UseBB->getTerminator()->isEHPad()) | |||||||||
3126 | continue; | |||||||||
3127 | // Ignore uses which are part of other SCEV expressions, to avoid | |||||||||
3128 | // analyzing them multiple times. | |||||||||
3129 | if (SE.isSCEVable(UserInst->getType())) { | |||||||||
3130 | const SCEV *UserS = SE.getSCEV(const_cast<Instruction *>(UserInst)); | |||||||||
3131 | // If the user is a no-op, look through to its uses. | |||||||||
3132 | if (!isa<SCEVUnknown>(UserS)) | |||||||||
3133 | continue; | |||||||||
3134 | if (UserS == US) { | |||||||||
3135 | Worklist.push_back( | |||||||||
3136 | SE.getUnknown(const_cast<Instruction *>(UserInst))); | |||||||||
3137 | continue; | |||||||||
3138 | } | |||||||||
3139 | } | |||||||||
3140 | // Ignore icmp instructions which are already being analyzed. | |||||||||
3141 | if (const ICmpInst *ICI = dyn_cast<ICmpInst>(UserInst)) { | |||||||||
3142 | unsigned OtherIdx = !U.getOperandNo(); | |||||||||
3143 | Value *OtherOp = const_cast<Value *>(ICI->getOperand(OtherIdx)); | |||||||||
3144 | if (SE.hasComputableLoopEvolution(SE.getSCEV(OtherOp), L)) | |||||||||
3145 | continue; | |||||||||
3146 | } | |||||||||
3147 | ||||||||||
3148 | std::pair<size_t, int64_t> P = getUse( | |||||||||
3149 | S, LSRUse::Basic, MemAccessTy()); | |||||||||
3150 | size_t LUIdx = P.first; | |||||||||
3151 | int64_t Offset = P.second; | |||||||||
3152 | LSRUse &LU = Uses[LUIdx]; | |||||||||
3153 | LSRFixup &LF = LU.getNewFixup(); | |||||||||
3154 | LF.UserInst = const_cast<Instruction *>(UserInst); | |||||||||
3155 | LF.OperandValToReplace = U; | |||||||||
3156 | LF.Offset = Offset; | |||||||||
3157 | LU.AllFixupsOutsideLoop &= LF.isUseFullyOutsideLoop(L); | |||||||||
3158 | if (!LU.WidestFixupType || | |||||||||
3159 | SE.getTypeSizeInBits(LU.WidestFixupType) < | |||||||||
3160 | SE.getTypeSizeInBits(LF.OperandValToReplace->getType())) | |||||||||
3161 | LU.WidestFixupType = LF.OperandValToReplace->getType(); | |||||||||
3162 | InsertSupplementalFormula(US, LU, LUIdx); | |||||||||
3163 | CountRegisters(LU.Formulae.back(), Uses.size() - 1); | |||||||||
3164 | break; | |||||||||
3165 | } | |||||||||
3166 | } | |||||||||
3167 | } | |||||||||
3168 | } | |||||||||
3169 | ||||||||||
3170 | /// Split S into subexpressions which can be pulled out into separate | |||||||||
3171 | /// registers. If C is non-null, multiply each subexpression by C. | |||||||||
3172 | /// | |||||||||
3173 | /// Return remainder expression after factoring the subexpressions captured by | |||||||||
3174 | /// Ops. If Ops is complete, return NULL. | |||||||||
3175 | static const SCEV *CollectSubexprs(const SCEV *S, const SCEVConstant *C, | |||||||||
3176 | SmallVectorImpl<const SCEV *> &Ops, | |||||||||
3177 | const Loop *L, | |||||||||
3178 | ScalarEvolution &SE, | |||||||||
3179 | unsigned Depth = 0) { | |||||||||
3180 | // Arbitrarily cap recursion to protect compile time. | |||||||||
3181 | if (Depth >= 3) | |||||||||
3182 | return S; | |||||||||
3183 | ||||||||||
3184 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) { | |||||||||
3185 | // Break out add operands. | |||||||||
3186 | for (const SCEV *S : Add->operands()) { | |||||||||
3187 | const SCEV *Remainder = CollectSubexprs(S, C, Ops, L, SE, Depth+1); | |||||||||
3188 | if (Remainder) | |||||||||
3189 | Ops.push_back(C ? SE.getMulExpr(C, Remainder) : Remainder); | |||||||||
3190 | } | |||||||||
3191 | return nullptr; | |||||||||
3192 | } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) { | |||||||||
3193 | // Split a non-zero base out of an addrec. | |||||||||
3194 | if (AR->getStart()->isZero()) | |||||||||
3195 | return S; | |||||||||
3196 | ||||||||||
3197 | const SCEV *Remainder = CollectSubexprs(AR->getStart(), | |||||||||
3198 | C, Ops, L, SE, Depth+1); | |||||||||
3199 | // Split the non-zero AddRec unless it is part of a nested recurrence that | |||||||||
3200 | // does not pertain to this loop. | |||||||||
3201 | if (Remainder && (AR->getLoop() == L || !isa<SCEVAddRecExpr>(Remainder))) { | |||||||||
3202 | Ops.push_back(C ? SE.getMulExpr(C, Remainder) : Remainder); | |||||||||
3203 | Remainder = nullptr; | |||||||||
3204 | } | |||||||||
3205 | if (Remainder != AR->getStart()) { | |||||||||
3206 | if (!Remainder) | |||||||||
3207 | Remainder = SE.getConstant(AR->getType(), 0); | |||||||||
3208 | return SE.getAddRecExpr(Remainder, | |||||||||
3209 | AR->getStepRecurrence(SE), | |||||||||
3210 | AR->getLoop(), | |||||||||
3211 | //FIXME: AR->getNoWrapFlags(SCEV::FlagNW) | |||||||||
3212 | SCEV::FlagAnyWrap); | |||||||||
3213 | } | |||||||||
3214 | } else if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) { | |||||||||
3215 | // Break (C * (a + b + c)) into C*a + C*b + C*c. | |||||||||
3216 | if (Mul->getNumOperands() != 2) | |||||||||
3217 | return S; | |||||||||
3218 | if (const SCEVConstant *Op0 = | |||||||||
3219 | dyn_cast<SCEVConstant>(Mul->getOperand(0))) { | |||||||||
3220 | C = C ? cast<SCEVConstant>(SE.getMulExpr(C, Op0)) : Op0; | |||||||||
3221 | const SCEV *Remainder = | |||||||||
3222 | CollectSubexprs(Mul->getOperand(1), C, Ops, L, SE, Depth+1); | |||||||||
3223 | if (Remainder) | |||||||||
3224 | Ops.push_back(SE.getMulExpr(C, Remainder)); | |||||||||
3225 | return nullptr; | |||||||||
3226 | } | |||||||||
3227 | } | |||||||||
3228 | return S; | |||||||||
3229 | } | |||||||||
3230 | ||||||||||
3231 | /// \brief Helper function for LSRInstance::GenerateReassociations. | |||||||||
3232 | void LSRInstance::GenerateReassociationsImpl(LSRUse &LU, unsigned LUIdx, | |||||||||
3233 | const Formula &Base, | |||||||||
3234 | unsigned Depth, size_t Idx, | |||||||||
3235 | bool IsScaledReg) { | |||||||||
3236 | const SCEV *BaseReg = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx]; | |||||||||
3237 | SmallVector<const SCEV *, 8> AddOps; | |||||||||
3238 | const SCEV *Remainder = CollectSubexprs(BaseReg, nullptr, AddOps, L, SE); | |||||||||
3239 | if (Remainder) | |||||||||
3240 | AddOps.push_back(Remainder); | |||||||||
3241 | ||||||||||
3242 | if (AddOps.size() == 1) | |||||||||
3243 | return; | |||||||||
3244 | ||||||||||
3245 | for (SmallVectorImpl<const SCEV *>::const_iterator J = AddOps.begin(), | |||||||||
3246 | JE = AddOps.end(); | |||||||||
3247 | J != JE; ++J) { | |||||||||
3248 | ||||||||||
3249 | // Loop-variant "unknown" values are uninteresting; we won't be able to | |||||||||
3250 | // do anything meaningful with them. | |||||||||
3251 | if (isa<SCEVUnknown>(*J) && !SE.isLoopInvariant(*J, L)) | |||||||||
3252 | continue; | |||||||||
3253 | ||||||||||
3254 | // Don't pull a constant into a register if the constant could be folded | |||||||||
3255 | // into an immediate field. | |||||||||
3256 | if (isAlwaysFoldable(TTI, SE, LU.MinOffset, LU.MaxOffset, LU.Kind, | |||||||||
3257 | LU.AccessTy, *J, Base.getNumRegs() > 1)) | |||||||||
3258 | continue; | |||||||||
3259 | ||||||||||
3260 | // Collect all operands except *J. | |||||||||
3261 | SmallVector<const SCEV *, 8> InnerAddOps( | |||||||||
3262 | ((const SmallVector<const SCEV *, 8> &)AddOps).begin(), J); | |||||||||
3263 | InnerAddOps.append(std::next(J), | |||||||||
3264 | ((const SmallVector<const SCEV *, 8> &)AddOps).end()); | |||||||||
3265 | ||||||||||
3266 | // Don't leave just a constant behind in a register if the constant could | |||||||||
3267 | // be folded into an immediate field. | |||||||||
3268 | if (InnerAddOps.size() == 1 && | |||||||||
3269 | isAlwaysFoldable(TTI, SE, LU.MinOffset, LU.MaxOffset, LU.Kind, | |||||||||
3270 | LU.AccessTy, InnerAddOps[0], Base.getNumRegs() > 1)) | |||||||||
3271 | continue; | |||||||||
3272 | ||||||||||
3273 | const SCEV *InnerSum = SE.getAddExpr(InnerAddOps); | |||||||||
3274 | if (InnerSum->isZero()) | |||||||||
3275 | continue; | |||||||||
3276 | Formula F = Base; | |||||||||
3277 | ||||||||||
3278 | // Add the remaining pieces of the add back into the new formula. | |||||||||
3279 | const SCEVConstant *InnerSumSC = dyn_cast<SCEVConstant>(InnerSum); | |||||||||
3280 | if (InnerSumSC && SE.getTypeSizeInBits(InnerSumSC->getType()) <= 64 && | |||||||||
3281 | TTI.isLegalAddImmediate((uint64_t)F.UnfoldedOffset + | |||||||||
3282 | InnerSumSC->getValue()->getZExtValue())) { | |||||||||
3283 | F.UnfoldedOffset = | |||||||||
3284 | (uint64_t)F.UnfoldedOffset + InnerSumSC->getValue()->getZExtValue(); | |||||||||
3285 | if (IsScaledReg) | |||||||||
3286 | F.ScaledReg = nullptr; | |||||||||
3287 | else | |||||||||
3288 | F.BaseRegs.erase(F.BaseRegs.begin() + Idx); | |||||||||
3289 | } else if (IsScaledReg) | |||||||||
3290 | F.ScaledReg = InnerSum; | |||||||||
3291 | else | |||||||||
3292 | F.BaseRegs[Idx] = InnerSum; | |||||||||
3293 | ||||||||||
3294 | // Add J as its own register, or an unfolded immediate. | |||||||||
3295 | const SCEVConstant *SC = dyn_cast<SCEVConstant>(*J); | |||||||||
3296 | if (SC && SE.getTypeSizeInBits(SC->getType()) <= 64 && | |||||||||
3297 | TTI.isLegalAddImmediate((uint64_t)F.UnfoldedOffset + | |||||||||
3298 | SC->getValue()->getZExtValue())) | |||||||||
3299 | F.UnfoldedOffset = | |||||||||
3300 | (uint64_t)F.UnfoldedOffset + SC->getValue()->getZExtValue(); | |||||||||
3301 | else | |||||||||
3302 | F.BaseRegs.push_back(*J); | |||||||||
3303 | // We may have changed the number of register in base regs, adjust the | |||||||||
3304 | // formula accordingly. | |||||||||
3305 | F.canonicalize(); | |||||||||
3306 | ||||||||||
3307 | if (InsertFormula(LU, LUIdx, F)) | |||||||||
3308 | // If that formula hadn't been seen before, recurse to find more like | |||||||||
3309 | // it. | |||||||||
3310 | GenerateReassociations(LU, LUIdx, LU.Formulae.back(), Depth + 1); | |||||||||
3311 | } | |||||||||
3312 | } | |||||||||
3313 | ||||||||||
3314 | /// Split out subexpressions from adds and the bases of addrecs. | |||||||||
3315 | void LSRInstance::GenerateReassociations(LSRUse &LU, unsigned LUIdx, | |||||||||
3316 | Formula Base, unsigned Depth) { | |||||||||
3317 | assert(Base.isCanonical() && "Input must be in the canonical form")((Base.isCanonical() && "Input must be in the canonical form" ) ? static_cast<void> (0) : __assert_fail ("Base.isCanonical() && \"Input must be in the canonical form\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3317, __PRETTY_FUNCTION__)); | |||||||||
3318 | // Arbitrarily cap recursion to protect compile time. | |||||||||
3319 | if (Depth >= 3) | |||||||||
3320 | return; | |||||||||
3321 | ||||||||||
3322 | for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i) | |||||||||
3323 | GenerateReassociationsImpl(LU, LUIdx, Base, Depth, i); | |||||||||
3324 | ||||||||||
3325 | if (Base.Scale == 1) | |||||||||
3326 | GenerateReassociationsImpl(LU, LUIdx, Base, Depth, | |||||||||
3327 | /* Idx */ -1, /* IsScaledReg */ true); | |||||||||
3328 | } | |||||||||
3329 | ||||||||||
3330 | /// Generate a formula consisting of all of the loop-dominating registers added | |||||||||
3331 | /// into a single register. | |||||||||
3332 | void LSRInstance::GenerateCombinations(LSRUse &LU, unsigned LUIdx, | |||||||||
3333 | Formula Base) { | |||||||||
3334 | // This method is only interesting on a plurality of registers. | |||||||||
3335 | if (Base.BaseRegs.size() + (Base.Scale == 1) <= 1) | |||||||||
3336 | return; | |||||||||
3337 | ||||||||||
3338 | // Flatten the representation, i.e., reg1 + 1*reg2 => reg1 + reg2, before | |||||||||
3339 | // processing the formula. | |||||||||
3340 | Base.unscale(); | |||||||||
3341 | Formula F = Base; | |||||||||
3342 | F.BaseRegs.clear(); | |||||||||
3343 | SmallVector<const SCEV *, 4> Ops; | |||||||||
3344 | for (const SCEV *BaseReg : Base.BaseRegs) { | |||||||||
3345 | if (SE.properlyDominates(BaseReg, L->getHeader()) && | |||||||||
3346 | !SE.hasComputableLoopEvolution(BaseReg, L)) | |||||||||
3347 | Ops.push_back(BaseReg); | |||||||||
3348 | else | |||||||||
3349 | F.BaseRegs.push_back(BaseReg); | |||||||||
3350 | } | |||||||||
3351 | if (Ops.size() > 1) { | |||||||||
3352 | const SCEV *Sum = SE.getAddExpr(Ops); | |||||||||
3353 | // TODO: If Sum is zero, it probably means ScalarEvolution missed an | |||||||||
3354 | // opportunity to fold something. For now, just ignore such cases | |||||||||
3355 | // rather than proceed with zero in a register. | |||||||||
3356 | if (!Sum->isZero()) { | |||||||||
3357 | F.BaseRegs.push_back(Sum); | |||||||||
3358 | F.canonicalize(); | |||||||||
3359 | (void)InsertFormula(LU, LUIdx, F); | |||||||||
3360 | } | |||||||||
3361 | } | |||||||||
3362 | } | |||||||||
3363 | ||||||||||
3364 | /// \brief Helper function for LSRInstance::GenerateSymbolicOffsets. | |||||||||
3365 | void LSRInstance::GenerateSymbolicOffsetsImpl(LSRUse &LU, unsigned LUIdx, | |||||||||
3366 | const Formula &Base, size_t Idx, | |||||||||
3367 | bool IsScaledReg) { | |||||||||
3368 | const SCEV *G = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx]; | |||||||||
3369 | GlobalValue *GV = ExtractSymbol(G, SE); | |||||||||
3370 | if (G->isZero() || !GV) | |||||||||
3371 | return; | |||||||||
3372 | Formula F = Base; | |||||||||
3373 | F.BaseGV = GV; | |||||||||
3374 | if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F)) | |||||||||
3375 | return; | |||||||||
3376 | if (IsScaledReg) | |||||||||
3377 | F.ScaledReg = G; | |||||||||
3378 | else | |||||||||
3379 | F.BaseRegs[Idx] = G; | |||||||||
3380 | (void)InsertFormula(LU, LUIdx, F); | |||||||||
3381 | } | |||||||||
3382 | ||||||||||
3383 | /// Generate reuse formulae using symbolic offsets. | |||||||||
3384 | void LSRInstance::GenerateSymbolicOffsets(LSRUse &LU, unsigned LUIdx, | |||||||||
3385 | Formula Base) { | |||||||||
3386 | // We can't add a symbolic offset if the address already contains one. | |||||||||
3387 | if (Base.BaseGV) return; | |||||||||
3388 | ||||||||||
3389 | for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i) | |||||||||
3390 | GenerateSymbolicOffsetsImpl(LU, LUIdx, Base, i); | |||||||||
3391 | if (Base.Scale == 1) | |||||||||
3392 | GenerateSymbolicOffsetsImpl(LU, LUIdx, Base, /* Idx */ -1, | |||||||||
3393 | /* IsScaledReg */ true); | |||||||||
3394 | } | |||||||||
3395 | ||||||||||
3396 | /// \brief Helper function for LSRInstance::GenerateConstantOffsets. | |||||||||
3397 | void LSRInstance::GenerateConstantOffsetsImpl( | |||||||||
3398 | LSRUse &LU, unsigned LUIdx, const Formula &Base, | |||||||||
3399 | const SmallVectorImpl<int64_t> &Worklist, size_t Idx, bool IsScaledReg) { | |||||||||
3400 | const SCEV *G = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx]; | |||||||||
3401 | for (int64_t Offset : Worklist) { | |||||||||
3402 | Formula F = Base; | |||||||||
3403 | F.BaseOffset = (uint64_t)Base.BaseOffset - Offset; | |||||||||
3404 | if (isLegalUse(TTI, LU.MinOffset - Offset, LU.MaxOffset - Offset, LU.Kind, | |||||||||
3405 | LU.AccessTy, F)) { | |||||||||
3406 | // Add the offset to the base register. | |||||||||
3407 | const SCEV *NewG = SE.getAddExpr(SE.getConstant(G->getType(), Offset), G); | |||||||||
3408 | // If it cancelled out, drop the base register, otherwise update it. | |||||||||
3409 | if (NewG->isZero()) { | |||||||||
3410 | if (IsScaledReg) { | |||||||||
3411 | F.Scale = 0; | |||||||||
3412 | F.ScaledReg = nullptr; | |||||||||
3413 | } else | |||||||||
3414 | F.deleteBaseReg(F.BaseRegs[Idx]); | |||||||||
3415 | F.canonicalize(); | |||||||||
3416 | } else if (IsScaledReg) | |||||||||
3417 | F.ScaledReg = NewG; | |||||||||
3418 | else | |||||||||
3419 | F.BaseRegs[Idx] = NewG; | |||||||||
3420 | ||||||||||
3421 | (void)InsertFormula(LU, LUIdx, F); | |||||||||
3422 | } | |||||||||
3423 | } | |||||||||
3424 | ||||||||||
3425 | int64_t Imm = ExtractImmediate(G, SE); | |||||||||
3426 | if (G->isZero() || Imm == 0) | |||||||||
3427 | return; | |||||||||
3428 | Formula F = Base; | |||||||||
3429 | F.BaseOffset = (uint64_t)F.BaseOffset + Imm; | |||||||||
3430 | if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F)) | |||||||||
3431 | return; | |||||||||
3432 | if (IsScaledReg) | |||||||||
3433 | F.ScaledReg = G; | |||||||||
3434 | else | |||||||||
3435 | F.BaseRegs[Idx] = G; | |||||||||
3436 | (void)InsertFormula(LU, LUIdx, F); | |||||||||
3437 | } | |||||||||
3438 | ||||||||||
3439 | /// GenerateConstantOffsets - Generate reuse formulae using symbolic offsets. | |||||||||
3440 | void LSRInstance::GenerateConstantOffsets(LSRUse &LU, unsigned LUIdx, | |||||||||
3441 | Formula Base) { | |||||||||
3442 | // TODO: For now, just add the min and max offset, because it usually isn't | |||||||||
3443 | // worthwhile looking at everything inbetween. | |||||||||
3444 | SmallVector<int64_t, 2> Worklist; | |||||||||
3445 | Worklist.push_back(LU.MinOffset); | |||||||||
3446 | if (LU.MaxOffset != LU.MinOffset) | |||||||||
3447 | Worklist.push_back(LU.MaxOffset); | |||||||||
3448 | ||||||||||
3449 | for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i) | |||||||||
3450 | GenerateConstantOffsetsImpl(LU, LUIdx, Base, Worklist, i); | |||||||||
3451 | if (Base.Scale == 1) | |||||||||
3452 | GenerateConstantOffsetsImpl(LU, LUIdx, Base, Worklist, /* Idx */ -1, | |||||||||
3453 | /* IsScaledReg */ true); | |||||||||
3454 | } | |||||||||
3455 | ||||||||||
3456 | /// For ICmpZero, check to see if we can scale up the comparison. For example, x | |||||||||
3457 | /// == y -> x*c == y*c. | |||||||||
3458 | void LSRInstance::GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx, | |||||||||
3459 | Formula Base) { | |||||||||
3460 | if (LU.Kind != LSRUse::ICmpZero) return; | |||||||||
3461 | ||||||||||
3462 | // Determine the integer type for the base formula. | |||||||||
3463 | Type *IntTy = Base.getType(); | |||||||||
3464 | if (!IntTy) return; | |||||||||
3465 | if (SE.getTypeSizeInBits(IntTy) > 64) return; | |||||||||
3466 | ||||||||||
3467 | // Don't do this if there is more than one offset. | |||||||||
3468 | if (LU.MinOffset != LU.MaxOffset) return; | |||||||||
3469 | ||||||||||
3470 | assert(!Base.BaseGV && "ICmpZero use is not legal!")((!Base.BaseGV && "ICmpZero use is not legal!") ? static_cast <void> (0) : __assert_fail ("!Base.BaseGV && \"ICmpZero use is not legal!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3470, __PRETTY_FUNCTION__)); | |||||||||
3471 | ||||||||||
3472 | // Check each interesting stride. | |||||||||
3473 | for (int64_t Factor : Factors) { | |||||||||
3474 | // Check that the multiplication doesn't overflow. | |||||||||
3475 | if (Base.BaseOffset == INT64_MIN(-9223372036854775807L -1) && Factor == -1) | |||||||||
3476 | continue; | |||||||||
3477 | int64_t NewBaseOffset = (uint64_t)Base.BaseOffset * Factor; | |||||||||
3478 | if (NewBaseOffset / Factor != Base.BaseOffset) | |||||||||
3479 | continue; | |||||||||
3480 | // If the offset will be truncated at this use, check that it is in bounds. | |||||||||
3481 | if (!IntTy->isPointerTy() && | |||||||||
3482 | !ConstantInt::isValueValidForType(IntTy, NewBaseOffset)) | |||||||||
3483 | continue; | |||||||||
3484 | ||||||||||
3485 | // Check that multiplying with the use offset doesn't overflow. | |||||||||
3486 | int64_t Offset = LU.MinOffset; | |||||||||
3487 | if (Offset == INT64_MIN(-9223372036854775807L -1) && Factor == -1) | |||||||||
3488 | continue; | |||||||||
3489 | Offset = (uint64_t)Offset * Factor; | |||||||||
3490 | if (Offset / Factor != LU.MinOffset) | |||||||||
3491 | continue; | |||||||||
3492 | // If the offset will be truncated at this use, check that it is in bounds. | |||||||||
3493 | if (!IntTy->isPointerTy() && | |||||||||
3494 | !ConstantInt::isValueValidForType(IntTy, Offset)) | |||||||||
3495 | continue; | |||||||||
3496 | ||||||||||
3497 | Formula F = Base; | |||||||||
3498 | F.BaseOffset = NewBaseOffset; | |||||||||
3499 | ||||||||||
3500 | // Check that this scale is legal. | |||||||||
3501 | if (!isLegalUse(TTI, Offset, Offset, LU.Kind, LU.AccessTy, F)) | |||||||||
3502 | continue; | |||||||||
3503 | ||||||||||
3504 | // Compensate for the use having MinOffset built into it. | |||||||||
3505 | F.BaseOffset = (uint64_t)F.BaseOffset + Offset - LU.MinOffset; | |||||||||
3506 | ||||||||||
3507 | const SCEV *FactorS = SE.getConstant(IntTy, Factor); | |||||||||
3508 | ||||||||||
3509 | // Check that multiplying with each base register doesn't overflow. | |||||||||
3510 | for (size_t i = 0, e = F.BaseRegs.size(); i != e; ++i) { | |||||||||
3511 | F.BaseRegs[i] = SE.getMulExpr(F.BaseRegs[i], FactorS); | |||||||||
3512 | if (getExactSDiv(F.BaseRegs[i], FactorS, SE) != Base.BaseRegs[i]) | |||||||||
3513 | goto next; | |||||||||
3514 | } | |||||||||
3515 | ||||||||||
3516 | // Check that multiplying with the scaled register doesn't overflow. | |||||||||
3517 | if (F.ScaledReg) { | |||||||||
3518 | F.ScaledReg = SE.getMulExpr(F.ScaledReg, FactorS); | |||||||||
3519 | if (getExactSDiv(F.ScaledReg, FactorS, SE) != Base.ScaledReg) | |||||||||
3520 | continue; | |||||||||
3521 | } | |||||||||
3522 | ||||||||||
3523 | // Check that multiplying with the unfolded offset doesn't overflow. | |||||||||
3524 | if (F.UnfoldedOffset != 0) { | |||||||||
3525 | if (F.UnfoldedOffset == INT64_MIN(-9223372036854775807L -1) && Factor == -1) | |||||||||
3526 | continue; | |||||||||
3527 | F.UnfoldedOffset = (uint64_t)F.UnfoldedOffset * Factor; | |||||||||
3528 | if (F.UnfoldedOffset / Factor != Base.UnfoldedOffset) | |||||||||
3529 | continue; | |||||||||
3530 | // If the offset will be truncated, check that it is in bounds. | |||||||||
3531 | if (!IntTy->isPointerTy() && | |||||||||
3532 | !ConstantInt::isValueValidForType(IntTy, F.UnfoldedOffset)) | |||||||||
3533 | continue; | |||||||||
3534 | } | |||||||||
3535 | ||||||||||
3536 | // If we make it here and it's legal, add it. | |||||||||
3537 | (void)InsertFormula(LU, LUIdx, F); | |||||||||
3538 | next:; | |||||||||
3539 | } | |||||||||
3540 | } | |||||||||
3541 | ||||||||||
3542 | /// Generate stride factor reuse formulae by making use of scaled-offset address | |||||||||
3543 | /// modes, for example. | |||||||||
3544 | void LSRInstance::GenerateScales(LSRUse &LU, unsigned LUIdx, Formula Base) { | |||||||||
3545 | // Determine the integer type for the base formula. | |||||||||
3546 | Type *IntTy = Base.getType(); | |||||||||
3547 | if (!IntTy) return; | |||||||||
3548 | ||||||||||
3549 | // If this Formula already has a scaled register, we can't add another one. | |||||||||
3550 | // Try to unscale the formula to generate a better scale. | |||||||||
3551 | if (Base.Scale != 0 && !Base.unscale()) | |||||||||
3552 | return; | |||||||||
3553 | ||||||||||
3554 | assert(Base.Scale == 0 && "unscale did not did its job!")((Base.Scale == 0 && "unscale did not did its job!") ? static_cast<void> (0) : __assert_fail ("Base.Scale == 0 && \"unscale did not did its job!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3554, __PRETTY_FUNCTION__)); | |||||||||
3555 | ||||||||||
3556 | // Check each interesting stride. | |||||||||
3557 | for (int64_t Factor : Factors) { | |||||||||
3558 | Base.Scale = Factor; | |||||||||
3559 | Base.HasBaseReg = Base.BaseRegs.size() > 1; | |||||||||
3560 | // Check whether this scale is going to be legal. | |||||||||
3561 | if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, | |||||||||
3562 | Base)) { | |||||||||
3563 | // As a special-case, handle special out-of-loop Basic users specially. | |||||||||
3564 | // TODO: Reconsider this special case. | |||||||||
3565 | if (LU.Kind == LSRUse::Basic && | |||||||||
3566 | isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LSRUse::Special, | |||||||||
3567 | LU.AccessTy, Base) && | |||||||||
3568 | LU.AllFixupsOutsideLoop) | |||||||||
3569 | LU.Kind = LSRUse::Special; | |||||||||
3570 | else | |||||||||
3571 | continue; | |||||||||
3572 | } | |||||||||
3573 | // For an ICmpZero, negating a solitary base register won't lead to | |||||||||
3574 | // new solutions. | |||||||||
3575 | if (LU.Kind == LSRUse::ICmpZero && | |||||||||
3576 | !Base.HasBaseReg && Base.BaseOffset == 0 && !Base.BaseGV) | |||||||||
3577 | continue; | |||||||||
3578 | // For each addrec base reg, apply the scale, if possible. | |||||||||
3579 | for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i) | |||||||||
3580 | if (const SCEVAddRecExpr *AR = | |||||||||
3581 | dyn_cast<SCEVAddRecExpr>(Base.BaseRegs[i])) { | |||||||||
3582 | const SCEV *FactorS = SE.getConstant(IntTy, Factor); | |||||||||
3583 | if (FactorS->isZero()) | |||||||||
3584 | continue; | |||||||||
3585 | // Divide out the factor, ignoring high bits, since we'll be | |||||||||
3586 | // scaling the value back up in the end. | |||||||||
3587 | if (const SCEV *Quotient = getExactSDiv(AR, FactorS, SE, true)) { | |||||||||
3588 | // TODO: This could be optimized to avoid all the copying. | |||||||||
3589 | Formula F = Base; | |||||||||
3590 | F.ScaledReg = Quotient; | |||||||||
3591 | F.deleteBaseReg(F.BaseRegs[i]); | |||||||||
3592 | // The canonical representation of 1*reg is reg, which is already in | |||||||||
3593 | // Base. In that case, do not try to insert the formula, it will be | |||||||||
3594 | // rejected anyway. | |||||||||
3595 | if (F.Scale == 1 && F.BaseRegs.empty()) | |||||||||
3596 | continue; | |||||||||
3597 | (void)InsertFormula(LU, LUIdx, F); | |||||||||
3598 | } | |||||||||
3599 | } | |||||||||
3600 | } | |||||||||
3601 | } | |||||||||
3602 | ||||||||||
3603 | /// Generate reuse formulae from different IV types. | |||||||||
3604 | void LSRInstance::GenerateTruncates(LSRUse &LU, unsigned LUIdx, Formula Base) { | |||||||||
3605 | // Don't bother truncating symbolic values. | |||||||||
3606 | if (Base.BaseGV) return; | |||||||||
3607 | ||||||||||
3608 | // Determine the integer type for the base formula. | |||||||||
3609 | Type *DstTy = Base.getType(); | |||||||||
3610 | if (!DstTy) return; | |||||||||
3611 | DstTy = SE.getEffectiveSCEVType(DstTy); | |||||||||
3612 | ||||||||||
3613 | for (Type *SrcTy : Types) { | |||||||||
3614 | if (SrcTy != DstTy && TTI.isTruncateFree(SrcTy, DstTy)) { | |||||||||
3615 | Formula F = Base; | |||||||||
3616 | ||||||||||
3617 | if (F.ScaledReg) F.ScaledReg = SE.getAnyExtendExpr(F.ScaledReg, SrcTy); | |||||||||
3618 | for (const SCEV *&BaseReg : F.BaseRegs) | |||||||||
3619 | BaseReg = SE.getAnyExtendExpr(BaseReg, SrcTy); | |||||||||
3620 | ||||||||||
3621 | // TODO: This assumes we've done basic processing on all uses and | |||||||||
3622 | // have an idea what the register usage is. | |||||||||
3623 | if (!F.hasRegsUsedByUsesOtherThan(LUIdx, RegUses)) | |||||||||
3624 | continue; | |||||||||
3625 | ||||||||||
3626 | (void)InsertFormula(LU, LUIdx, F); | |||||||||
3627 | } | |||||||||
3628 | } | |||||||||
3629 | } | |||||||||
3630 | ||||||||||
3631 | namespace { | |||||||||
3632 | ||||||||||
3633 | /// Helper class for GenerateCrossUseConstantOffsets. It's used to defer | |||||||||
3634 | /// modifications so that the search phase doesn't have to worry about the data | |||||||||
3635 | /// structures moving underneath it. | |||||||||
3636 | struct WorkItem { | |||||||||
3637 | size_t LUIdx; | |||||||||
3638 | int64_t Imm; | |||||||||
3639 | const SCEV *OrigReg; | |||||||||
3640 | ||||||||||
3641 | WorkItem(size_t LI, int64_t I, const SCEV *R) | |||||||||
3642 | : LUIdx(LI), Imm(I), OrigReg(R) {} | |||||||||
3643 | ||||||||||
3644 | void print(raw_ostream &OS) const; | |||||||||
3645 | void dump() const; | |||||||||
3646 | }; | |||||||||
3647 | ||||||||||
3648 | } | |||||||||
3649 | ||||||||||
3650 | void WorkItem::print(raw_ostream &OS) const { | |||||||||
3651 | OS << "in formulae referencing " << *OrigReg << " in use " << LUIdx | |||||||||
3652 | << " , add offset " << Imm; | |||||||||
3653 | } | |||||||||
3654 | ||||||||||
3655 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) | |||||||||
3656 | void WorkItem::dump() const { | |||||||||
3657 | print(errs()); errs() << '\n'; | |||||||||
3658 | } | |||||||||
3659 | ||||||||||
3660 | /// Look for registers which are a constant distance apart and try to form reuse | |||||||||
3661 | /// opportunities between them. | |||||||||
3662 | void LSRInstance::GenerateCrossUseConstantOffsets() { | |||||||||
3663 | // Group the registers by their value without any added constant offset. | |||||||||
3664 | typedef std::map<int64_t, const SCEV *> ImmMapTy; | |||||||||
3665 | DenseMap<const SCEV *, ImmMapTy> Map; | |||||||||
3666 | DenseMap<const SCEV *, SmallBitVector> UsedByIndicesMap; | |||||||||
3667 | SmallVector<const SCEV *, 8> Sequence; | |||||||||
3668 | for (const SCEV *Use : RegUses) { | |||||||||
3669 | const SCEV *Reg = Use; // Make a copy for ExtractImmediate to modify. | |||||||||
3670 | int64_t Imm = ExtractImmediate(Reg, SE); | |||||||||
3671 | auto Pair = Map.insert(std::make_pair(Reg, ImmMapTy())); | |||||||||
3672 | if (Pair.second) | |||||||||
3673 | Sequence.push_back(Reg); | |||||||||
3674 | Pair.first->second.insert(std::make_pair(Imm, Use)); | |||||||||
3675 | UsedByIndicesMap[Reg] |= RegUses.getUsedByIndices(Use); | |||||||||
3676 | } | |||||||||
3677 | ||||||||||
3678 | // Now examine each set of registers with the same base value. Build up | |||||||||
3679 | // a list of work to do and do the work in a separate step so that we're | |||||||||
3680 | // not adding formulae and register counts while we're searching. | |||||||||
3681 | SmallVector<WorkItem, 32> WorkItems; | |||||||||
3682 | SmallSet<std::pair<size_t, int64_t>, 32> UniqueItems; | |||||||||
3683 | for (const SCEV *Reg : Sequence) { | |||||||||
3684 | const ImmMapTy &Imms = Map.find(Reg)->second; | |||||||||
3685 | ||||||||||
3686 | // It's not worthwhile looking for reuse if there's only one offset. | |||||||||
3687 | if (Imms.size() == 1) | |||||||||
3688 | continue; | |||||||||
3689 | ||||||||||
3690 | DEBUG(dbgs() << "Generating cross-use offsets for " << *Reg << ':';do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Generating cross-use offsets for " << *Reg << ':'; for (const auto &Entry : Imms ) dbgs() << ' ' << Entry.first; dbgs() << '\n' ; } } while (false) | |||||||||
3691 | for (const auto &Entry : Imms)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Generating cross-use offsets for " << *Reg << ':'; for (const auto &Entry : Imms ) dbgs() << ' ' << Entry.first; dbgs() << '\n' ; } } while (false) | |||||||||
3692 | dbgs() << ' ' << Entry.first;do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Generating cross-use offsets for " << *Reg << ':'; for (const auto &Entry : Imms ) dbgs() << ' ' << Entry.first; dbgs() << '\n' ; } } while (false) | |||||||||
3693 | dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Generating cross-use offsets for " << *Reg << ':'; for (const auto &Entry : Imms ) dbgs() << ' ' << Entry.first; dbgs() << '\n' ; } } while (false); | |||||||||
3694 | ||||||||||
3695 | // Examine each offset. | |||||||||
3696 | for (ImmMapTy::const_iterator J = Imms.begin(), JE = Imms.end(); | |||||||||
3697 | J != JE; ++J) { | |||||||||
3698 | const SCEV *OrigReg = J->second; | |||||||||
3699 | ||||||||||
3700 | int64_t JImm = J->first; | |||||||||
3701 | const SmallBitVector &UsedByIndices = RegUses.getUsedByIndices(OrigReg); | |||||||||
3702 | ||||||||||
3703 | if (!isa<SCEVConstant>(OrigReg) && | |||||||||
3704 | UsedByIndicesMap[Reg].count() == 1) { | |||||||||
3705 | DEBUG(dbgs() << "Skipping cross-use reuse for " << *OrigReg << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Skipping cross-use reuse for " << *OrigReg << '\n'; } } while (false); | |||||||||
3706 | continue; | |||||||||
3707 | } | |||||||||
3708 | ||||||||||
3709 | // Conservatively examine offsets between this orig reg a few selected | |||||||||
3710 | // other orig regs. | |||||||||
3711 | ImmMapTy::const_iterator OtherImms[] = { | |||||||||
3712 | Imms.begin(), std::prev(Imms.end()), | |||||||||
3713 | Imms.lower_bound((Imms.begin()->first + std::prev(Imms.end())->first) / | |||||||||
3714 | 2) | |||||||||
3715 | }; | |||||||||
3716 | for (size_t i = 0, e = array_lengthof(OtherImms); i != e; ++i) { | |||||||||
3717 | ImmMapTy::const_iterator M = OtherImms[i]; | |||||||||
3718 | if (M == J || M == JE) continue; | |||||||||
3719 | ||||||||||
3720 | // Compute the difference between the two. | |||||||||
3721 | int64_t Imm = (uint64_t)JImm - M->first; | |||||||||
3722 | for (int LUIdx = UsedByIndices.find_first(); LUIdx != -1; | |||||||||
3723 | LUIdx = UsedByIndices.find_next(LUIdx)) | |||||||||
3724 | // Make a memo of this use, offset, and register tuple. | |||||||||
3725 | if (UniqueItems.insert(std::make_pair(LUIdx, Imm)).second) | |||||||||
3726 | WorkItems.push_back(WorkItem(LUIdx, Imm, OrigReg)); | |||||||||
3727 | } | |||||||||
3728 | } | |||||||||
3729 | } | |||||||||
3730 | ||||||||||
3731 | Map.clear(); | |||||||||
3732 | Sequence.clear(); | |||||||||
3733 | UsedByIndicesMap.clear(); | |||||||||
3734 | UniqueItems.clear(); | |||||||||
3735 | ||||||||||
3736 | // Now iterate through the worklist and add new formulae. | |||||||||
3737 | for (const WorkItem &WI : WorkItems) { | |||||||||
3738 | size_t LUIdx = WI.LUIdx; | |||||||||
3739 | LSRUse &LU = Uses[LUIdx]; | |||||||||
3740 | int64_t Imm = WI.Imm; | |||||||||
3741 | const SCEV *OrigReg = WI.OrigReg; | |||||||||
3742 | ||||||||||
3743 | Type *IntTy = SE.getEffectiveSCEVType(OrigReg->getType()); | |||||||||
3744 | const SCEV *NegImmS = SE.getSCEV(ConstantInt::get(IntTy, -(uint64_t)Imm)); | |||||||||
3745 | unsigned BitWidth = SE.getTypeSizeInBits(IntTy); | |||||||||
3746 | ||||||||||
3747 | // TODO: Use a more targeted data structure. | |||||||||
3748 | for (size_t L = 0, LE = LU.Formulae.size(); L != LE; ++L) { | |||||||||
3749 | Formula F = LU.Formulae[L]; | |||||||||
3750 | // FIXME: The code for the scaled and unscaled registers looks | |||||||||
3751 | // very similar but slightly different. Investigate if they | |||||||||
3752 | // could be merged. That way, we would not have to unscale the | |||||||||
3753 | // Formula. | |||||||||
3754 | F.unscale(); | |||||||||
3755 | // Use the immediate in the scaled register. | |||||||||
3756 | if (F.ScaledReg == OrigReg) { | |||||||||
3757 | int64_t Offset = (uint64_t)F.BaseOffset + Imm * (uint64_t)F.Scale; | |||||||||
3758 | // Don't create 50 + reg(-50). | |||||||||
3759 | if (F.referencesReg(SE.getSCEV( | |||||||||
3760 | ConstantInt::get(IntTy, -(uint64_t)Offset)))) | |||||||||
3761 | continue; | |||||||||
3762 | Formula NewF = F; | |||||||||
3763 | NewF.BaseOffset = Offset; | |||||||||
3764 | if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, | |||||||||
3765 | NewF)) | |||||||||
3766 | continue; | |||||||||
3767 | NewF.ScaledReg = SE.getAddExpr(NegImmS, NewF.ScaledReg); | |||||||||
3768 | ||||||||||
3769 | // If the new scale is a constant in a register, and adding the constant | |||||||||
3770 | // value to the immediate would produce a value closer to zero than the | |||||||||
3771 | // immediate itself, then the formula isn't worthwhile. | |||||||||
3772 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(NewF.ScaledReg)) | |||||||||
3773 | if (C->getValue()->isNegative() != (NewF.BaseOffset < 0) && | |||||||||
3774 | (C->getAPInt().abs() * APInt(BitWidth, F.Scale)) | |||||||||
3775 | .ule(std::abs(NewF.BaseOffset))) | |||||||||
3776 | continue; | |||||||||
3777 | ||||||||||
3778 | // OK, looks good. | |||||||||
3779 | NewF.canonicalize(); | |||||||||
3780 | (void)InsertFormula(LU, LUIdx, NewF); | |||||||||
3781 | } else { | |||||||||
3782 | // Use the immediate in a base register. | |||||||||
3783 | for (size_t N = 0, NE = F.BaseRegs.size(); N != NE; ++N) { | |||||||||
3784 | const SCEV *BaseReg = F.BaseRegs[N]; | |||||||||
3785 | if (BaseReg != OrigReg) | |||||||||
3786 | continue; | |||||||||
3787 | Formula NewF = F; | |||||||||
3788 | NewF.BaseOffset = (uint64_t)NewF.BaseOffset + Imm; | |||||||||
3789 | if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, | |||||||||
3790 | LU.Kind, LU.AccessTy, NewF)) { | |||||||||
3791 | if (!TTI.isLegalAddImmediate((uint64_t)NewF.UnfoldedOffset + Imm)) | |||||||||
3792 | continue; | |||||||||
3793 | NewF = F; | |||||||||
3794 | NewF.UnfoldedOffset = (uint64_t)NewF.UnfoldedOffset + Imm; | |||||||||
3795 | } | |||||||||
3796 | NewF.BaseRegs[N] = SE.getAddExpr(NegImmS, BaseReg); | |||||||||
3797 | ||||||||||
3798 | // If the new formula has a constant in a register, and adding the | |||||||||
3799 | // constant value to the immediate would produce a value closer to | |||||||||
3800 | // zero than the immediate itself, then the formula isn't worthwhile. | |||||||||
3801 | for (const SCEV *NewReg : NewF.BaseRegs) | |||||||||
3802 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(NewReg)) | |||||||||
3803 | if ((C->getAPInt() + NewF.BaseOffset) | |||||||||
3804 | .abs() | |||||||||
3805 | .slt(std::abs(NewF.BaseOffset)) && | |||||||||
3806 | (C->getAPInt() + NewF.BaseOffset).countTrailingZeros() >= | |||||||||
3807 | countTrailingZeros<uint64_t>(NewF.BaseOffset)) | |||||||||
3808 | goto skip_formula; | |||||||||
3809 | ||||||||||
3810 | // Ok, looks good. | |||||||||
3811 | NewF.canonicalize(); | |||||||||
3812 | (void)InsertFormula(LU, LUIdx, NewF); | |||||||||
3813 | break; | |||||||||
3814 | skip_formula:; | |||||||||
3815 | } | |||||||||
3816 | } | |||||||||
3817 | } | |||||||||
3818 | } | |||||||||
3819 | } | |||||||||
3820 | ||||||||||
3821 | /// Generate formulae for each use. | |||||||||
3822 | void | |||||||||
3823 | LSRInstance::GenerateAllReuseFormulae() { | |||||||||
3824 | // This is split into multiple loops so that hasRegsUsedByUsesOtherThan | |||||||||
3825 | // queries are more precise. | |||||||||
3826 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { | |||||||||
3827 | LSRUse &LU = Uses[LUIdx]; | |||||||||
3828 | for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) | |||||||||
3829 | GenerateReassociations(LU, LUIdx, LU.Formulae[i]); | |||||||||
3830 | for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) | |||||||||
3831 | GenerateCombinations(LU, LUIdx, LU.Formulae[i]); | |||||||||
3832 | } | |||||||||
3833 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { | |||||||||
3834 | LSRUse &LU = Uses[LUIdx]; | |||||||||
3835 | for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) | |||||||||
3836 | GenerateSymbolicOffsets(LU, LUIdx, LU.Formulae[i]); | |||||||||
3837 | for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) | |||||||||
3838 | GenerateConstantOffsets(LU, LUIdx, LU.Formulae[i]); | |||||||||
3839 | for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) | |||||||||
3840 | GenerateICmpZeroScales(LU, LUIdx, LU.Formulae[i]); | |||||||||
3841 | for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) | |||||||||
3842 | GenerateScales(LU, LUIdx, LU.Formulae[i]); | |||||||||
3843 | } | |||||||||
3844 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { | |||||||||
3845 | LSRUse &LU = Uses[LUIdx]; | |||||||||
3846 | for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) | |||||||||
3847 | GenerateTruncates(LU, LUIdx, LU.Formulae[i]); | |||||||||
3848 | } | |||||||||
3849 | ||||||||||
3850 | GenerateCrossUseConstantOffsets(); | |||||||||
3851 | ||||||||||
3852 | DEBUG(dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\n" "After generating reuse formulae:\n" ; print_uses(dbgs()); } } while (false) | |||||||||
3853 | "After generating reuse formulae:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\n" "After generating reuse formulae:\n" ; print_uses(dbgs()); } } while (false) | |||||||||
3854 | print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\n" "After generating reuse formulae:\n" ; print_uses(dbgs()); } } while (false); | |||||||||
3855 | } | |||||||||
3856 | ||||||||||
3857 | /// If there are multiple formulae with the same set of registers used | |||||||||
3858 | /// by other uses, pick the best one and delete the others. | |||||||||
3859 | void LSRInstance::FilterOutUndesirableDedicatedRegisters() { | |||||||||
3860 | DenseSet<const SCEV *> VisitedRegs; | |||||||||
3861 | SmallPtrSet<const SCEV *, 16> Regs; | |||||||||
3862 | SmallPtrSet<const SCEV *, 16> LoserRegs; | |||||||||
3863 | #ifndef NDEBUG | |||||||||
3864 | bool ChangedFormulae = false; | |||||||||
3865 | #endif | |||||||||
3866 | ||||||||||
3867 | // Collect the best formula for each unique set of shared registers. This | |||||||||
3868 | // is reset for each use. | |||||||||
3869 | typedef DenseMap<SmallVector<const SCEV *, 4>, size_t, UniquifierDenseMapInfo> | |||||||||
3870 | BestFormulaeTy; | |||||||||
3871 | BestFormulaeTy BestFormulae; | |||||||||
3872 | ||||||||||
3873 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { | |||||||||
3874 | LSRUse &LU = Uses[LUIdx]; | |||||||||
3875 | DEBUG(dbgs() << "Filtering for use "; LU.print(dbgs()); dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Filtering for use "; LU.print (dbgs()); dbgs() << '\n'; } } while (false); | |||||||||
3876 | ||||||||||
3877 | bool Any = false; | |||||||||
3878 | for (size_t FIdx = 0, NumForms = LU.Formulae.size(); | |||||||||
3879 | FIdx != NumForms; ++FIdx) { | |||||||||
3880 | Formula &F = LU.Formulae[FIdx]; | |||||||||
3881 | ||||||||||
3882 | // Some formulas are instant losers. For example, they may depend on | |||||||||
3883 | // nonexistent AddRecs from other loops. These need to be filtered | |||||||||
3884 | // immediately, otherwise heuristics could choose them over others leading | |||||||||
3885 | // to an unsatisfactory solution. Passing LoserRegs into RateFormula here | |||||||||
3886 | // avoids the need to recompute this information across formulae using the | |||||||||
3887 | // same bad AddRec. Passing LoserRegs is also essential unless we remove | |||||||||
3888 | // the corresponding bad register from the Regs set. | |||||||||
3889 | Cost CostF; | |||||||||
3890 | Regs.clear(); | |||||||||
3891 | CostF.RateFormula(TTI, F, Regs, VisitedRegs, L, SE, DT, LU, &LoserRegs); | |||||||||
3892 | if (CostF.isLoser()) { | |||||||||
3893 | // During initial formula generation, undesirable formulae are generated | |||||||||
3894 | // by uses within other loops that have some non-trivial address mode or | |||||||||
3895 | // use the postinc form of the IV. LSR needs to provide these formulae | |||||||||
3896 | // as the basis of rediscovering the desired formula that uses an AddRec | |||||||||
3897 | // corresponding to the existing phi. Once all formulae have been | |||||||||
3898 | // generated, these initial losers may be pruned. | |||||||||
3899 | DEBUG(dbgs() << " Filtering loser "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Filtering loser "; F.print (dbgs()); dbgs() << "\n"; } } while (false) | |||||||||
3900 | dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Filtering loser "; F.print (dbgs()); dbgs() << "\n"; } } while (false); | |||||||||
3901 | } | |||||||||
3902 | else { | |||||||||
3903 | SmallVector<const SCEV *, 4> Key; | |||||||||
3904 | for (const SCEV *Reg : F.BaseRegs) { | |||||||||
3905 | if (RegUses.isRegUsedByUsesOtherThan(Reg, LUIdx)) | |||||||||
3906 | Key.push_back(Reg); | |||||||||
3907 | } | |||||||||
3908 | if (F.ScaledReg && | |||||||||
3909 | RegUses.isRegUsedByUsesOtherThan(F.ScaledReg, LUIdx)) | |||||||||
3910 | Key.push_back(F.ScaledReg); | |||||||||
3911 | // Unstable sort by host order ok, because this is only used for | |||||||||
3912 | // uniquifying. | |||||||||
3913 | std::sort(Key.begin(), Key.end()); | |||||||||
3914 | ||||||||||
3915 | std::pair<BestFormulaeTy::const_iterator, bool> P = | |||||||||
3916 | BestFormulae.insert(std::make_pair(Key, FIdx)); | |||||||||
3917 | if (P.second) | |||||||||
3918 | continue; | |||||||||
3919 | ||||||||||
3920 | Formula &Best = LU.Formulae[P.first->second]; | |||||||||
3921 | ||||||||||
3922 | Cost CostBest; | |||||||||
3923 | Regs.clear(); | |||||||||
3924 | CostBest.RateFormula(TTI, Best, Regs, VisitedRegs, L, SE, DT, LU); | |||||||||
3925 | if (CostF < CostBest) | |||||||||
3926 | std::swap(F, Best); | |||||||||
3927 | DEBUG(dbgs() << " Filtering out formula "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Filtering out formula " ; F.print(dbgs()); dbgs() << "\n" " in favor of formula " ; Best.print(dbgs()); dbgs() << '\n'; } } while (false) | |||||||||
3928 | dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Filtering out formula " ; F.print(dbgs()); dbgs() << "\n" " in favor of formula " ; Best.print(dbgs()); dbgs() << '\n'; } } while (false) | |||||||||
3929 | " in favor of formula "; Best.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Filtering out formula " ; F.print(dbgs()); dbgs() << "\n" " in favor of formula " ; Best.print(dbgs()); dbgs() << '\n'; } } while (false) | |||||||||
3930 | dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Filtering out formula " ; F.print(dbgs()); dbgs() << "\n" " in favor of formula " ; Best.print(dbgs()); dbgs() << '\n'; } } while (false); | |||||||||
3931 | } | |||||||||
3932 | #ifndef NDEBUG | |||||||||
3933 | ChangedFormulae = true; | |||||||||
3934 | #endif | |||||||||
3935 | LU.DeleteFormula(F); | |||||||||
3936 | --FIdx; | |||||||||
3937 | --NumForms; | |||||||||
3938 | Any = true; | |||||||||
3939 | } | |||||||||
3940 | ||||||||||
3941 | // Now that we've filtered out some formulae, recompute the Regs set. | |||||||||
3942 | if (Any) | |||||||||
3943 | LU.RecomputeRegs(LUIdx, RegUses); | |||||||||
3944 | ||||||||||
3945 | // Reset this to prepare for the next use. | |||||||||
3946 | BestFormulae.clear(); | |||||||||
3947 | } | |||||||||
3948 | ||||||||||
3949 | DEBUG(if (ChangedFormulae) {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n" "After filtering out undesirable candidates:\n"; print_uses( dbgs()); }; } } while (false) | |||||||||
3950 | dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n" "After filtering out undesirable candidates:\n"; print_uses( dbgs()); }; } } while (false) | |||||||||
3951 | "After filtering out undesirable candidates:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n" "After filtering out undesirable candidates:\n"; print_uses( dbgs()); }; } } while (false) | |||||||||
3952 | print_uses(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n" "After filtering out undesirable candidates:\n"; print_uses( dbgs()); }; } } while (false) | |||||||||
3953 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n" "After filtering out undesirable candidates:\n"; print_uses( dbgs()); }; } } while (false); | |||||||||
3954 | } | |||||||||
3955 | ||||||||||
3956 | // This is a rough guess that seems to work fairly well. | |||||||||
3957 | static const size_t ComplexityLimit = UINT16_MAX(65535); | |||||||||
3958 | ||||||||||
3959 | /// Estimate the worst-case number of solutions the solver might have to | |||||||||
3960 | /// consider. It almost never considers this many solutions because it prune the | |||||||||
3961 | /// search space, but the pruning isn't always sufficient. | |||||||||
3962 | size_t LSRInstance::EstimateSearchSpaceComplexity() const { | |||||||||
3963 | size_t Power = 1; | |||||||||
3964 | for (const LSRUse &LU : Uses) { | |||||||||
3965 | size_t FSize = LU.Formulae.size(); | |||||||||
3966 | if (FSize >= ComplexityLimit) { | |||||||||
3967 | Power = ComplexityLimit; | |||||||||
3968 | break; | |||||||||
3969 | } | |||||||||
3970 | Power *= FSize; | |||||||||
3971 | if (Power >= ComplexityLimit) | |||||||||
3972 | break; | |||||||||
3973 | } | |||||||||
3974 | return Power; | |||||||||
3975 | } | |||||||||
3976 | ||||||||||
3977 | /// When one formula uses a superset of the registers of another formula, it | |||||||||
3978 | /// won't help reduce register pressure (though it may not necessarily hurt | |||||||||
3979 | /// register pressure); remove it to simplify the system. | |||||||||
3980 | void LSRInstance::NarrowSearchSpaceByDetectingSupersets() { | |||||||||
3981 | if (EstimateSearchSpaceComplexity() >= ComplexityLimit) { | |||||||||
3982 | DEBUG(dbgs() << "The search space is too complex.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "The search space is too complex.\n" ; } } while (false); | |||||||||
3983 | ||||||||||
3984 | DEBUG(dbgs() << "Narrowing the search space by eliminating formulae "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Narrowing the search space by eliminating formulae " "which use a superset of registers used by other " "formulae.\n" ; } } while (false) | |||||||||
3985 | "which use a superset of registers used by other "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Narrowing the search space by eliminating formulae " "which use a superset of registers used by other " "formulae.\n" ; } } while (false) | |||||||||
3986 | "formulae.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Narrowing the search space by eliminating formulae " "which use a superset of registers used by other " "formulae.\n" ; } } while (false); | |||||||||
3987 | ||||||||||
3988 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { | |||||||||
3989 | LSRUse &LU = Uses[LUIdx]; | |||||||||
3990 | bool Any = false; | |||||||||
3991 | for (size_t i = 0, e = LU.Formulae.size(); i != e; ++i) { | |||||||||
3992 | Formula &F = LU.Formulae[i]; | |||||||||
3993 | // Look for a formula with a constant or GV in a register. If the use | |||||||||
3994 | // also has a formula with that same value in an immediate field, | |||||||||
3995 | // delete the one that uses a register. | |||||||||
3996 | for (SmallVectorImpl<const SCEV *>::const_iterator | |||||||||
3997 | I = F.BaseRegs.begin(), E = F.BaseRegs.end(); I != E; ++I) { | |||||||||
3998 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(*I)) { | |||||||||
3999 | Formula NewF = F; | |||||||||
4000 | NewF.BaseOffset += C->getValue()->getSExtValue(); | |||||||||
4001 | NewF.BaseRegs.erase(NewF.BaseRegs.begin() + | |||||||||
4002 | (I - F.BaseRegs.begin())); | |||||||||
4003 | if (LU.HasFormulaWithSameRegs(NewF)) { | |||||||||
4004 | DEBUG(dbgs() << " Deleting "; F.print(dbgs()); dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs ()); dbgs() << '\n'; } } while (false); | |||||||||
4005 | LU.DeleteFormula(F); | |||||||||
4006 | --i; | |||||||||
4007 | --e; | |||||||||
4008 | Any = true; | |||||||||
4009 | break; | |||||||||
4010 | } | |||||||||
4011 | } else if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(*I)) { | |||||||||
4012 | if (GlobalValue *GV = dyn_cast<GlobalValue>(U->getValue())) | |||||||||
4013 | if (!F.BaseGV) { | |||||||||
4014 | Formula NewF = F; | |||||||||
4015 | NewF.BaseGV = GV; | |||||||||
4016 | NewF.BaseRegs.erase(NewF.BaseRegs.begin() + | |||||||||
4017 | (I - F.BaseRegs.begin())); | |||||||||
4018 | if (LU.HasFormulaWithSameRegs(NewF)) { | |||||||||
4019 | DEBUG(dbgs() << " Deleting "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs ()); dbgs() << '\n'; } } while (false) | |||||||||
4020 | dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs ()); dbgs() << '\n'; } } while (false); | |||||||||
4021 | LU.DeleteFormula(F); | |||||||||
4022 | --i; | |||||||||
4023 | --e; | |||||||||
4024 | Any = true; | |||||||||
4025 | break; | |||||||||
4026 | } | |||||||||
4027 | } | |||||||||
4028 | } | |||||||||
4029 | } | |||||||||
4030 | } | |||||||||
4031 | if (Any) | |||||||||
4032 | LU.RecomputeRegs(LUIdx, RegUses); | |||||||||
4033 | } | |||||||||
4034 | ||||||||||
4035 | DEBUG(dbgs() << "After pre-selection:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses (dbgs()); } } while (false) | |||||||||
4036 | print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses (dbgs()); } } while (false); | |||||||||
4037 | } | |||||||||
4038 | } | |||||||||
4039 | ||||||||||
4040 | /// When there are many registers for expressions like A, A+1, A+2, etc., | |||||||||
4041 | /// allocate a single register for them. | |||||||||
4042 | void LSRInstance::NarrowSearchSpaceByCollapsingUnrolledCode() { | |||||||||
4043 | if (EstimateSearchSpaceComplexity() < ComplexityLimit) | |||||||||
4044 | return; | |||||||||
4045 | ||||||||||
4046 | DEBUG(dbgs() << "The search space is too complex.\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "The search space is too complex.\n" "Narrowing the search space by assuming that uses separated " "by a constant offset will use the same registers.\n"; } } while (false) | |||||||||
4047 | "Narrowing the search space by assuming that uses separated "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "The search space is too complex.\n" "Narrowing the search space by assuming that uses separated " "by a constant offset will use the same registers.\n"; } } while (false) | |||||||||
4048 | "by a constant offset will use the same registers.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "The search space is too complex.\n" "Narrowing the search space by assuming that uses separated " "by a constant offset will use the same registers.\n"; } } while (false); | |||||||||
4049 | ||||||||||
4050 | // This is especially useful for unrolled loops. | |||||||||
4051 | ||||||||||
4052 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { | |||||||||
4053 | LSRUse &LU = Uses[LUIdx]; | |||||||||
4054 | for (const Formula &F : LU.Formulae) { | |||||||||
4055 | if (F.BaseOffset == 0 || (F.Scale != 0 && F.Scale != 1)) | |||||||||
4056 | continue; | |||||||||
4057 | ||||||||||
4058 | LSRUse *LUThatHas = FindUseWithSimilarFormula(F, LU); | |||||||||
4059 | if (!LUThatHas) | |||||||||
4060 | continue; | |||||||||
4061 | ||||||||||
4062 | if (!reconcileNewOffset(*LUThatHas, F.BaseOffset, /*HasBaseReg=*/ false, | |||||||||
4063 | LU.Kind, LU.AccessTy)) | |||||||||
4064 | continue; | |||||||||
4065 | ||||||||||
4066 | DEBUG(dbgs() << " Deleting use "; LU.print(dbgs()); dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Deleting use "; LU.print (dbgs()); dbgs() << '\n'; } } while (false); | |||||||||
4067 | ||||||||||
4068 | LUThatHas->AllFixupsOutsideLoop &= LU.AllFixupsOutsideLoop; | |||||||||
4069 | ||||||||||
4070 | // Transfer the fixups of LU to LUThatHas. | |||||||||
4071 | for (LSRFixup &Fixup : LU.Fixups) { | |||||||||
4072 | Fixup.Offset += F.BaseOffset; | |||||||||
4073 | LUThatHas->pushFixup(Fixup); | |||||||||
4074 | DEBUG(dbgs() << "New fixup has offset " << Fixup.Offset << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "New fixup has offset " << Fixup.Offset << '\n'; } } while (false); | |||||||||
4075 | } | |||||||||
4076 | ||||||||||
4077 | // Delete formulae from the new use which are no longer legal. | |||||||||
4078 | bool Any = false; | |||||||||
4079 | for (size_t i = 0, e = LUThatHas->Formulae.size(); i != e; ++i) { | |||||||||
4080 | Formula &F = LUThatHas->Formulae[i]; | |||||||||
4081 | if (!isLegalUse(TTI, LUThatHas->MinOffset, LUThatHas->MaxOffset, | |||||||||
4082 | LUThatHas->Kind, LUThatHas->AccessTy, F)) { | |||||||||
4083 | DEBUG(dbgs() << " Deleting "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs ()); dbgs() << '\n'; } } while (false) | |||||||||
4084 | dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs ()); dbgs() << '\n'; } } while (false); | |||||||||
4085 | LUThatHas->DeleteFormula(F); | |||||||||
4086 | --i; | |||||||||
4087 | --e; | |||||||||
4088 | Any = true; | |||||||||
4089 | } | |||||||||
4090 | } | |||||||||
4091 | ||||||||||
4092 | if (Any) | |||||||||
4093 | LUThatHas->RecomputeRegs(LUThatHas - &Uses.front(), RegUses); | |||||||||
4094 | ||||||||||
4095 | // Delete the old use. | |||||||||
4096 | DeleteUse(LU, LUIdx); | |||||||||
4097 | --LUIdx; | |||||||||
4098 | --NumUses; | |||||||||
4099 | break; | |||||||||
4100 | } | |||||||||
4101 | } | |||||||||
4102 | ||||||||||
4103 | DEBUG(dbgs() << "After pre-selection:\n"; print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses (dbgs()); } } while (false); | |||||||||
4104 | } | |||||||||
4105 | ||||||||||
4106 | /// Call FilterOutUndesirableDedicatedRegisters again, if necessary, now that | |||||||||
4107 | /// we've done more filtering, as it may be able to find more formulae to | |||||||||
4108 | /// eliminate. | |||||||||
4109 | void LSRInstance::NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters(){ | |||||||||
4110 | if (EstimateSearchSpaceComplexity() >= ComplexityLimit) { | |||||||||
4111 | DEBUG(dbgs() << "The search space is too complex.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "The search space is too complex.\n" ; } } while (false); | |||||||||
4112 | ||||||||||
4113 | DEBUG(dbgs() << "Narrowing the search space by re-filtering out "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Narrowing the search space by re-filtering out " "undesirable dedicated registers.\n"; } } while (false) | |||||||||
4114 | "undesirable dedicated registers.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Narrowing the search space by re-filtering out " "undesirable dedicated registers.\n"; } } while (false); | |||||||||
4115 | ||||||||||
4116 | FilterOutUndesirableDedicatedRegisters(); | |||||||||
4117 | ||||||||||
4118 | DEBUG(dbgs() << "After pre-selection:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses (dbgs()); } } while (false) | |||||||||
4119 | print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses (dbgs()); } } while (false); | |||||||||
4120 | } | |||||||||
4121 | } | |||||||||
4122 | ||||||||||
4123 | /// Pick a register which seems likely to be profitable, and then in any use | |||||||||
4124 | /// which has any reference to that register, delete all formulae which do not | |||||||||
4125 | /// reference that register. | |||||||||
4126 | void LSRInstance::NarrowSearchSpaceByPickingWinnerRegs() { | |||||||||
4127 | // With all other options exhausted, loop until the system is simple | |||||||||
4128 | // enough to handle. | |||||||||
4129 | SmallPtrSet<const SCEV *, 4> Taken; | |||||||||
4130 | while (EstimateSearchSpaceComplexity() >= ComplexityLimit) { | |||||||||
| ||||||||||
4131 | // Ok, we have too many of formulae on our hands to conveniently handle. | |||||||||
4132 | // Use a rough heuristic to thin out the list. | |||||||||
4133 | DEBUG(dbgs() << "The search space is too complex.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "The search space is too complex.\n" ; } } while (false); | |||||||||
4134 | ||||||||||
4135 | // Pick the register which is used by the most LSRUses, which is likely | |||||||||
4136 | // to be a good reuse register candidate. | |||||||||
4137 | const SCEV *Best = nullptr; | |||||||||
4138 | unsigned BestNum = 0; | |||||||||
4139 | for (const SCEV *Reg : RegUses) { | |||||||||
4140 | if (Taken.count(Reg)) | |||||||||
4141 | continue; | |||||||||
4142 | if (!Best) | |||||||||
4143 | Best = Reg; | |||||||||
4144 | else { | |||||||||
4145 | unsigned Count = RegUses.getUsedByIndices(Reg).count(); | |||||||||
4146 | if (Count > BestNum) { | |||||||||
4147 | Best = Reg; | |||||||||
4148 | BestNum = Count; | |||||||||
4149 | } | |||||||||
4150 | } | |||||||||
4151 | } | |||||||||
4152 | ||||||||||
4153 | DEBUG(dbgs() << "Narrowing the search space by assuming " << *Bestdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Narrowing the search space by assuming " << *Best << " will yield profitable reuse.\n"; } } while (false) | |||||||||
| ||||||||||
4154 | << " will yield profitable reuse.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Narrowing the search space by assuming " << *Best << " will yield profitable reuse.\n"; } } while (false); | |||||||||
4155 | Taken.insert(Best); | |||||||||
4156 | ||||||||||
4157 | // In any use with formulae which references this register, delete formulae | |||||||||
4158 | // which don't reference it. | |||||||||
4159 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { | |||||||||
4160 | LSRUse &LU = Uses[LUIdx]; | |||||||||
4161 | if (!LU.Regs.count(Best)) continue; | |||||||||
4162 | ||||||||||
4163 | bool Any = false; | |||||||||
4164 | for (size_t i = 0, e = LU.Formulae.size(); i != e; ++i) { | |||||||||
4165 | Formula &F = LU.Formulae[i]; | |||||||||
4166 | if (!F.referencesReg(Best)) { | |||||||||
4167 | DEBUG(dbgs() << " Deleting "; F.print(dbgs()); dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs ()); dbgs() << '\n'; } } while (false); | |||||||||
4168 | LU.DeleteFormula(F); | |||||||||
4169 | --e; | |||||||||
4170 | --i; | |||||||||
4171 | Any = true; | |||||||||
4172 | assert(e != 0 && "Use has no formulae left! Is Regs inconsistent?")((e != 0 && "Use has no formulae left! Is Regs inconsistent?" ) ? static_cast<void> (0) : __assert_fail ("e != 0 && \"Use has no formulae left! Is Regs inconsistent?\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4172, __PRETTY_FUNCTION__)); | |||||||||
4173 | continue; | |||||||||
4174 | } | |||||||||
4175 | } | |||||||||
4176 | ||||||||||
4177 | if (Any) | |||||||||
4178 | LU.RecomputeRegs(LUIdx, RegUses); | |||||||||
4179 | } | |||||||||
4180 | ||||||||||
4181 | DEBUG(dbgs() << "After pre-selection:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses (dbgs()); } } while (false) | |||||||||
4182 | print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses (dbgs()); } } while (false); | |||||||||
4183 | } | |||||||||
4184 | } | |||||||||
4185 | ||||||||||
4186 | /// If there are an extraordinary number of formulae to choose from, use some | |||||||||
4187 | /// rough heuristics to prune down the number of formulae. This keeps the main | |||||||||
4188 | /// solver from taking an extraordinary amount of time in some worst-case | |||||||||
4189 | /// scenarios. | |||||||||
4190 | void LSRInstance::NarrowSearchSpaceUsingHeuristics() { | |||||||||
4191 | NarrowSearchSpaceByDetectingSupersets(); | |||||||||
4192 | NarrowSearchSpaceByCollapsingUnrolledCode(); | |||||||||
4193 | NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters(); | |||||||||
4194 | NarrowSearchSpaceByPickingWinnerRegs(); | |||||||||
4195 | } | |||||||||
4196 | ||||||||||
4197 | /// This is the recursive solver. | |||||||||
4198 | void LSRInstance::SolveRecurse(SmallVectorImpl<const Formula *> &Solution, | |||||||||
4199 | Cost &SolutionCost, | |||||||||
4200 | SmallVectorImpl<const Formula *> &Workspace, | |||||||||
4201 | const Cost &CurCost, | |||||||||
4202 | const SmallPtrSet<const SCEV *, 16> &CurRegs, | |||||||||
4203 | DenseSet<const SCEV *> &VisitedRegs) const { | |||||||||
4204 | // Some ideas: | |||||||||
4205 | // - prune more: | |||||||||
4206 | // - use more aggressive filtering | |||||||||
4207 | // - sort the formula so that the most profitable solutions are found first | |||||||||
4208 | // - sort the uses too | |||||||||
4209 | // - search faster: | |||||||||
4210 | // - don't compute a cost, and then compare. compare while computing a cost | |||||||||
4211 | // and bail early. | |||||||||
4212 | // - track register sets with SmallBitVector | |||||||||
4213 | ||||||||||
4214 | const LSRUse &LU = Uses[Workspace.size()]; | |||||||||
4215 | ||||||||||
4216 | // If this use references any register that's already a part of the | |||||||||
4217 | // in-progress solution, consider it a requirement that a formula must | |||||||||
4218 | // reference that register in order to be considered. This prunes out | |||||||||
4219 | // unprofitable searching. | |||||||||
4220 | SmallSetVector<const SCEV *, 4> ReqRegs; | |||||||||
4221 | for (const SCEV *S : CurRegs) | |||||||||
4222 | if (LU.Regs.count(S)) | |||||||||
4223 | ReqRegs.insert(S); | |||||||||
4224 | ||||||||||
4225 | SmallPtrSet<const SCEV *, 16> NewRegs; | |||||||||
4226 | Cost NewCost; | |||||||||
4227 | for (const Formula &F : LU.Formulae) { | |||||||||
4228 | // Ignore formulae which may not be ideal in terms of register reuse of | |||||||||
4229 | // ReqRegs. The formula should use all required registers before | |||||||||
4230 | // introducing new ones. | |||||||||
4231 | int NumReqRegsToFind = std::min(F.getNumRegs(), ReqRegs.size()); | |||||||||
4232 | for (const SCEV *Reg : ReqRegs) { | |||||||||
4233 | if ((F.ScaledReg && F.ScaledReg == Reg) || | |||||||||
4234 | is_contained(F.BaseRegs, Reg)) { | |||||||||
4235 | --NumReqRegsToFind; | |||||||||
4236 | if (NumReqRegsToFind == 0) | |||||||||
4237 | break; | |||||||||
4238 | } | |||||||||
4239 | } | |||||||||
4240 | if (NumReqRegsToFind != 0) { | |||||||||
4241 | // If none of the formulae satisfied the required registers, then we could | |||||||||
4242 | // clear ReqRegs and try again. Currently, we simply give up in this case. | |||||||||
4243 | continue; | |||||||||
4244 | } | |||||||||
4245 | ||||||||||
4246 | // Evaluate the cost of the current formula. If it's already worse than | |||||||||
4247 | // the current best, prune the search at that point. | |||||||||
4248 | NewCost = CurCost; | |||||||||
4249 | NewRegs = CurRegs; | |||||||||
4250 | NewCost.RateFormula(TTI, F, NewRegs, VisitedRegs, L, SE, DT, LU); | |||||||||
4251 | if (NewCost < SolutionCost) { | |||||||||
4252 | Workspace.push_back(&F); | |||||||||
4253 | if (Workspace.size() != Uses.size()) { | |||||||||
4254 | SolveRecurse(Solution, SolutionCost, Workspace, NewCost, | |||||||||
4255 | NewRegs, VisitedRegs); | |||||||||
4256 | if (F.getNumRegs() == 1 && Workspace.size() == 1) | |||||||||
4257 | VisitedRegs.insert(F.ScaledReg ? F.ScaledReg : F.BaseRegs[0]); | |||||||||
4258 | } else { | |||||||||
4259 | DEBUG(dbgs() << "New best at "; NewCost.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "New best at "; NewCost.print (dbgs()); dbgs() << ".\n Regs:"; for (const SCEV *S : NewRegs ) dbgs() << ' ' << *S; dbgs() << '\n'; } } while (false) | |||||||||
4260 | dbgs() << ".\n Regs:";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "New best at "; NewCost.print (dbgs()); dbgs() << ".\n Regs:"; for (const SCEV *S : NewRegs ) dbgs() << ' ' << *S; dbgs() << '\n'; } } while (false) | |||||||||
4261 | for (const SCEV *S : NewRegs)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "New best at "; NewCost.print (dbgs()); dbgs() << ".\n Regs:"; for (const SCEV *S : NewRegs ) dbgs() << ' ' << *S; dbgs() << '\n'; } } while (false) | |||||||||
4262 | dbgs() << ' ' << *S;do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "New best at "; NewCost.print (dbgs()); dbgs() << ".\n Regs:"; for (const SCEV *S : NewRegs ) dbgs() << ' ' << *S; dbgs() << '\n'; } } while (false) | |||||||||
4263 | dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "New best at "; NewCost.print (dbgs()); dbgs() << ".\n Regs:"; for (const SCEV *S : NewRegs ) dbgs() << ' ' << *S; dbgs() << '\n'; } } while (false); | |||||||||
4264 | ||||||||||
4265 | SolutionCost = NewCost; | |||||||||
4266 | Solution = Workspace; | |||||||||
4267 | } | |||||||||
4268 | Workspace.pop_back(); | |||||||||
4269 | } | |||||||||
4270 | } | |||||||||
4271 | } | |||||||||
4272 | ||||||||||
4273 | /// Choose one formula from each use. Return the results in the given Solution | |||||||||
4274 | /// vector. | |||||||||
4275 | void LSRInstance::Solve(SmallVectorImpl<const Formula *> &Solution) const { | |||||||||
4276 | SmallVector<const Formula *, 8> Workspace; | |||||||||
4277 | Cost SolutionCost; | |||||||||
4278 | SolutionCost.Lose(); | |||||||||
4279 | Cost CurCost; | |||||||||
4280 | SmallPtrSet<const SCEV *, 16> CurRegs; | |||||||||
4281 | DenseSet<const SCEV *> VisitedRegs; | |||||||||
4282 | Workspace.reserve(Uses.size()); | |||||||||
4283 | ||||||||||
4284 | // SolveRecurse does all the work. | |||||||||
4285 | SolveRecurse(Solution, SolutionCost, Workspace, CurCost, | |||||||||
4286 | CurRegs, VisitedRegs); | |||||||||
4287 | if (Solution.empty()) { | |||||||||
4288 | DEBUG(dbgs() << "\nNo Satisfactory Solution\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\nNo Satisfactory Solution\n" ; } } while (false); | |||||||||
4289 | return; | |||||||||
4290 | } | |||||||||
4291 | ||||||||||
4292 | // Ok, we've now made all our decisions. | |||||||||
4293 | DEBUG(dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\n" "The chosen solution requires " ; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " "; Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution [i]->print(dbgs()); dbgs() << '\n'; }; } } while (false ) | |||||||||
4294 | "The chosen solution requires "; SolutionCost.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\n" "The chosen solution requires " ; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " "; Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution [i]->print(dbgs()); dbgs() << '\n'; }; } } while (false ) | |||||||||
4295 | dbgs() << ":\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\n" "The chosen solution requires " ; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " "; Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution [i]->print(dbgs()); dbgs() << '\n'; }; } } while (false ) | |||||||||
4296 | for (size_t i = 0, e = Uses.size(); i != e; ++i) {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\n" "The chosen solution requires " ; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " "; Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution [i]->print(dbgs()); dbgs() << '\n'; }; } } while (false ) | |||||||||
4297 | dbgs() << " ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\n" "The chosen solution requires " ; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " "; Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution [i]->print(dbgs()); dbgs() << '\n'; }; } } while (false ) | |||||||||
4298 | Uses[i].print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\n" "The chosen solution requires " ; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " "; Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution [i]->print(dbgs()); dbgs() << '\n'; }; } } while (false ) | |||||||||
4299 | dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\n" "The chosen solution requires " ; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " "; Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution [i]->print(dbgs()); dbgs() << '\n'; }; } } while (false ) | |||||||||
4300 | " ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\n" "The chosen solution requires " ; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " "; Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution [i]->print(dbgs()); dbgs() << '\n'; }; } } while (false ) | |||||||||
4301 | Solution[i]->print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\n" "The chosen solution requires " ; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " "; Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution [i]->print(dbgs()); dbgs() << '\n'; }; } } while (false ) | |||||||||
4302 | dbgs() << '\n';do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\n" "The chosen solution requires " ; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " "; Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution [i]->print(dbgs()); dbgs() << '\n'; }; } } while (false ) | |||||||||
4303 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\n" "The chosen solution requires " ; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " "; Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution [i]->print(dbgs()); dbgs() << '\n'; }; } } while (false ); | |||||||||
4304 | ||||||||||
4305 | assert(Solution.size() == Uses.size() && "Malformed solution!")((Solution.size() == Uses.size() && "Malformed solution!" ) ? static_cast<void> (0) : __assert_fail ("Solution.size() == Uses.size() && \"Malformed solution!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4305, __PRETTY_FUNCTION__)); | |||||||||
4306 | } | |||||||||
4307 | ||||||||||
4308 | /// Helper for AdjustInsertPositionForExpand. Climb up the dominator tree far as | |||||||||
4309 | /// we can go while still being dominated by the input positions. This helps | |||||||||
4310 | /// canonicalize the insert position, which encourages sharing. | |||||||||
4311 | BasicBlock::iterator | |||||||||
4312 | LSRInstance::HoistInsertPosition(BasicBlock::iterator IP, | |||||||||
4313 | const SmallVectorImpl<Instruction *> &Inputs) | |||||||||
4314 | const { | |||||||||
4315 | Instruction *Tentative = &*IP; | |||||||||
4316 | for (;;) { | |||||||||
4317 | bool AllDominate = true; | |||||||||
4318 | Instruction *BetterPos = nullptr; | |||||||||
4319 | // Don't bother attempting to insert before a catchswitch, their basic block | |||||||||
4320 | // cannot have other non-PHI instructions. | |||||||||
4321 | if (isa<CatchSwitchInst>(Tentative)) | |||||||||
4322 | return IP; | |||||||||
4323 | ||||||||||
4324 | for (Instruction *Inst : Inputs) { | |||||||||
4325 | if (Inst == Tentative || !DT.dominates(Inst, Tentative)) { | |||||||||
4326 | AllDominate = false; | |||||||||
4327 | break; | |||||||||
4328 | } | |||||||||
4329 | // Attempt to find an insert position in the middle of the block, | |||||||||
4330 | // instead of at the end, so that it can be used for other expansions. | |||||||||
4331 | if (Tentative->getParent() == Inst->getParent() && | |||||||||
4332 | (!BetterPos || !DT.dominates(Inst, BetterPos))) | |||||||||
4333 | BetterPos = &*std::next(BasicBlock::iterator(Inst)); | |||||||||
4334 | } | |||||||||
4335 | if (!AllDominate) | |||||||||
4336 | break; | |||||||||
4337 | if (BetterPos) | |||||||||
4338 | IP = BetterPos->getIterator(); | |||||||||
4339 | else | |||||||||
4340 | IP = Tentative->getIterator(); | |||||||||
4341 | ||||||||||
4342 | const Loop *IPLoop = LI.getLoopFor(IP->getParent()); | |||||||||
4343 | unsigned IPLoopDepth = IPLoop ? IPLoop->getLoopDepth() : 0; | |||||||||
4344 | ||||||||||
4345 | BasicBlock *IDom; | |||||||||
4346 | for (DomTreeNode *Rung = DT.getNode(IP->getParent()); ; ) { | |||||||||
4347 | if (!Rung) return IP; | |||||||||
4348 | Rung = Rung->getIDom(); | |||||||||
4349 | if (!Rung) return IP; | |||||||||
4350 | IDom = Rung->getBlock(); | |||||||||
4351 | ||||||||||
4352 | // Don't climb into a loop though. | |||||||||
4353 | const Loop *IDomLoop = LI.getLoopFor(IDom); | |||||||||
4354 | unsigned IDomDepth = IDomLoop ? IDomLoop->getLoopDepth() : 0; | |||||||||
4355 | if (IDomDepth <= IPLoopDepth && | |||||||||
4356 | (IDomDepth != IPLoopDepth || IDomLoop == IPLoop)) | |||||||||
4357 | break; | |||||||||
4358 | } | |||||||||
4359 | ||||||||||
4360 | Tentative = IDom->getTerminator(); | |||||||||
4361 | } | |||||||||
4362 | ||||||||||
4363 | return IP; | |||||||||
4364 | } | |||||||||
4365 | ||||||||||
4366 | /// Determine an input position which will be dominated by the operands and | |||||||||
4367 | /// which will dominate the result. | |||||||||
4368 | BasicBlock::iterator | |||||||||
4369 | LSRInstance::AdjustInsertPositionForExpand(BasicBlock::iterator LowestIP, | |||||||||
4370 | const LSRFixup &LF, | |||||||||
4371 | const LSRUse &LU, | |||||||||
4372 | SCEVExpander &Rewriter) const { | |||||||||
4373 | // Collect some instructions which must be dominated by the | |||||||||
4374 | // expanding replacement. These must be dominated by any operands that | |||||||||
4375 | // will be required in the expansion. | |||||||||
4376 | SmallVector<Instruction *, 4> Inputs; | |||||||||
4377 | if (Instruction *I = dyn_cast<Instruction>(LF.OperandValToReplace)) | |||||||||
4378 | Inputs.push_back(I); | |||||||||
4379 | if (LU.Kind == LSRUse::ICmpZero) | |||||||||
4380 | if (Instruction *I = | |||||||||
4381 | dyn_cast<Instruction>(cast<ICmpInst>(LF.UserInst)->getOperand(1))) | |||||||||
4382 | Inputs.push_back(I); | |||||||||
4383 | if (LF.PostIncLoops.count(L)) { | |||||||||
4384 | if (LF.isUseFullyOutsideLoop(L)) | |||||||||
4385 | Inputs.push_back(L->getLoopLatch()->getTerminator()); | |||||||||
4386 | else | |||||||||
4387 | Inputs.push_back(IVIncInsertPos); | |||||||||
4388 | } | |||||||||
4389 | // The expansion must also be dominated by the increment positions of any | |||||||||
4390 | // loops it for which it is using post-inc mode. | |||||||||
4391 | for (const Loop *PIL : LF.PostIncLoops) { | |||||||||
4392 | if (PIL == L) continue; | |||||||||
4393 | ||||||||||
4394 | // Be dominated by the loop exit. | |||||||||
4395 | SmallVector<BasicBlock *, 4> ExitingBlocks; | |||||||||
4396 | PIL->getExitingBlocks(ExitingBlocks); | |||||||||
4397 | if (!ExitingBlocks.empty()) { | |||||||||
4398 | BasicBlock *BB = ExitingBlocks[0]; | |||||||||
4399 | for (unsigned i = 1, e = ExitingBlocks.size(); i != e; ++i) | |||||||||
4400 | BB = DT.findNearestCommonDominator(BB, ExitingBlocks[i]); | |||||||||
4401 | Inputs.push_back(BB->getTerminator()); | |||||||||
4402 | } | |||||||||
4403 | } | |||||||||
4404 | ||||||||||
4405 | assert(!isa<PHINode>(LowestIP) && !LowestIP->isEHPad()((!isa<PHINode>(LowestIP) && !LowestIP->isEHPad () && !isa<DbgInfoIntrinsic>(LowestIP) && "Insertion point must be a normal instruction") ? static_cast <void> (0) : __assert_fail ("!isa<PHINode>(LowestIP) && !LowestIP->isEHPad() && !isa<DbgInfoIntrinsic>(LowestIP) && \"Insertion point must be a normal instruction\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4407, __PRETTY_FUNCTION__)) | |||||||||
4406 | && !isa<DbgInfoIntrinsic>(LowestIP) &&((!isa<PHINode>(LowestIP) && !LowestIP->isEHPad () && !isa<DbgInfoIntrinsic>(LowestIP) && "Insertion point must be a normal instruction") ? static_cast <void> (0) : __assert_fail ("!isa<PHINode>(LowestIP) && !LowestIP->isEHPad() && !isa<DbgInfoIntrinsic>(LowestIP) && \"Insertion point must be a normal instruction\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4407, __PRETTY_FUNCTION__)) | |||||||||
4407 | "Insertion point must be a normal instruction")((!isa<PHINode>(LowestIP) && !LowestIP->isEHPad () && !isa<DbgInfoIntrinsic>(LowestIP) && "Insertion point must be a normal instruction") ? static_cast <void> (0) : __assert_fail ("!isa<PHINode>(LowestIP) && !LowestIP->isEHPad() && !isa<DbgInfoIntrinsic>(LowestIP) && \"Insertion point must be a normal instruction\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4407, __PRETTY_FUNCTION__)); | |||||||||
4408 | ||||||||||
4409 | // Then, climb up the immediate dominator tree as far as we can go while | |||||||||
4410 | // still being dominated by the input positions. | |||||||||
4411 | BasicBlock::iterator IP = HoistInsertPosition(LowestIP, Inputs); | |||||||||
4412 | ||||||||||
4413 | // Don't insert instructions before PHI nodes. | |||||||||
4414 | while (isa<PHINode>(IP)) ++IP; | |||||||||
4415 | ||||||||||
4416 | // Ignore landingpad instructions. | |||||||||
4417 | while (IP->isEHPad()) ++IP; | |||||||||
4418 | ||||||||||
4419 | // Ignore debug intrinsics. | |||||||||
4420 | while (isa<DbgInfoIntrinsic>(IP)) ++IP; | |||||||||
4421 | ||||||||||
4422 | // Set IP below instructions recently inserted by SCEVExpander. This keeps the | |||||||||
4423 | // IP consistent across expansions and allows the previously inserted | |||||||||
4424 | // instructions to be reused by subsequent expansion. | |||||||||
4425 | while (Rewriter.isInsertedInstruction(&*IP) && IP != LowestIP) | |||||||||
4426 | ++IP; | |||||||||
4427 | ||||||||||
4428 | return IP; | |||||||||
4429 | } | |||||||||
4430 | ||||||||||
4431 | /// Emit instructions for the leading candidate expression for this LSRUse (this | |||||||||
4432 | /// is called "expanding"). | |||||||||
4433 | Value *LSRInstance::Expand(const LSRUse &LU, | |||||||||
4434 | const LSRFixup &LF, | |||||||||
4435 | const Formula &F, | |||||||||
4436 | BasicBlock::iterator IP, | |||||||||
4437 | SCEVExpander &Rewriter, | |||||||||
4438 | SmallVectorImpl<WeakVH> &DeadInsts) const { | |||||||||
4439 | if (LU.RigidFormula) | |||||||||
4440 | return LF.OperandValToReplace; | |||||||||
4441 | ||||||||||
4442 | // Determine an input position which will be dominated by the operands and | |||||||||
4443 | // which will dominate the result. | |||||||||
4444 | IP = AdjustInsertPositionForExpand(IP, LF, LU, Rewriter); | |||||||||
4445 | Rewriter.setInsertPoint(&*IP); | |||||||||
4446 | ||||||||||
4447 | // Inform the Rewriter if we have a post-increment use, so that it can | |||||||||
4448 | // perform an advantageous expansion. | |||||||||
4449 | Rewriter.setPostInc(LF.PostIncLoops); | |||||||||
4450 | ||||||||||
4451 | // This is the type that the user actually needs. | |||||||||
4452 | Type *OpTy = LF.OperandValToReplace->getType(); | |||||||||
4453 | // This will be the type that we'll initially expand to. | |||||||||
4454 | Type *Ty = F.getType(); | |||||||||
4455 | if (!Ty) | |||||||||
4456 | // No type known; just expand directly to the ultimate type. | |||||||||
4457 | Ty = OpTy; | |||||||||
4458 | else if (SE.getEffectiveSCEVType(Ty) == SE.getEffectiveSCEVType(OpTy)) | |||||||||
4459 | // Expand directly to the ultimate type if it's the right size. | |||||||||
4460 | Ty = OpTy; | |||||||||
4461 | // This is the type to do integer arithmetic in. | |||||||||
4462 | Type *IntTy = SE.getEffectiveSCEVType(Ty); | |||||||||
4463 | ||||||||||
4464 | // Build up a list of operands to add together to form the full base. | |||||||||
4465 | SmallVector<const SCEV *, 8> Ops; | |||||||||
4466 | ||||||||||
4467 | // Expand the BaseRegs portion. | |||||||||
4468 | for (const SCEV *Reg : F.BaseRegs) { | |||||||||
4469 | assert(!Reg->isZero() && "Zero allocated in a base register!")((!Reg->isZero() && "Zero allocated in a base register!" ) ? static_cast<void> (0) : __assert_fail ("!Reg->isZero() && \"Zero allocated in a base register!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4469, __PRETTY_FUNCTION__)); | |||||||||
4470 | ||||||||||
4471 | // If we're expanding for a post-inc user, make the post-inc adjustment. | |||||||||
4472 | PostIncLoopSet &Loops = const_cast<PostIncLoopSet &>(LF.PostIncLoops); | |||||||||
4473 | Reg = TransformForPostIncUse(Denormalize, Reg, | |||||||||
4474 | LF.UserInst, LF.OperandValToReplace, | |||||||||
4475 | Loops, SE, DT); | |||||||||
4476 | ||||||||||
4477 | Ops.push_back(SE.getUnknown(Rewriter.expandCodeFor(Reg, nullptr))); | |||||||||
4478 | } | |||||||||
4479 | ||||||||||
4480 | // Expand the ScaledReg portion. | |||||||||
4481 | Value *ICmpScaledV = nullptr; | |||||||||
4482 | if (F.Scale != 0) { | |||||||||
4483 | const SCEV *ScaledS = F.ScaledReg; | |||||||||
4484 | ||||||||||
4485 | // If we're expanding for a post-inc user, make the post-inc adjustment. | |||||||||
4486 | PostIncLoopSet &Loops = const_cast<PostIncLoopSet &>(LF.PostIncLoops); | |||||||||
4487 | ScaledS = TransformForPostIncUse(Denormalize, ScaledS, | |||||||||
4488 | LF.UserInst, LF.OperandValToReplace, | |||||||||
4489 | Loops, SE, DT); | |||||||||
4490 | ||||||||||
4491 | if (LU.Kind == LSRUse::ICmpZero) { | |||||||||
4492 | // Expand ScaleReg as if it was part of the base regs. | |||||||||
4493 | if (F.Scale == 1) | |||||||||
4494 | Ops.push_back( | |||||||||
4495 | SE.getUnknown(Rewriter.expandCodeFor(ScaledS, nullptr))); | |||||||||
4496 | else { | |||||||||
4497 | // An interesting way of "folding" with an icmp is to use a negated | |||||||||
4498 | // scale, which we'll implement by inserting it into the other operand | |||||||||
4499 | // of the icmp. | |||||||||
4500 | assert(F.Scale == -1 &&((F.Scale == -1 && "The only scale supported by ICmpZero uses is -1!" ) ? static_cast<void> (0) : __assert_fail ("F.Scale == -1 && \"The only scale supported by ICmpZero uses is -1!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4501, __PRETTY_FUNCTION__)) | |||||||||
4501 | "The only scale supported by ICmpZero uses is -1!")((F.Scale == -1 && "The only scale supported by ICmpZero uses is -1!" ) ? static_cast<void> (0) : __assert_fail ("F.Scale == -1 && \"The only scale supported by ICmpZero uses is -1!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4501, __PRETTY_FUNCTION__)); | |||||||||
4502 | ICmpScaledV = Rewriter.expandCodeFor(ScaledS, nullptr); | |||||||||
4503 | } | |||||||||
4504 | } else { | |||||||||
4505 | // Otherwise just expand the scaled register and an explicit scale, | |||||||||
4506 | // which is expected to be matched as part of the address. | |||||||||
4507 | ||||||||||
4508 | // Flush the operand list to suppress SCEVExpander hoisting address modes. | |||||||||
4509 | // Unless the addressing mode will not be folded. | |||||||||
4510 | if (!Ops.empty() && LU.Kind == LSRUse::Address && | |||||||||
4511 | isAMCompletelyFolded(TTI, LU, F)) { | |||||||||
4512 | Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty); | |||||||||
4513 | Ops.clear(); | |||||||||
4514 | Ops.push_back(SE.getUnknown(FullV)); | |||||||||
4515 | } | |||||||||
4516 | ScaledS = SE.getUnknown(Rewriter.expandCodeFor(ScaledS, nullptr)); | |||||||||
4517 | if (F.Scale != 1) | |||||||||
4518 | ScaledS = | |||||||||
4519 | SE.getMulExpr(ScaledS, SE.getConstant(ScaledS->getType(), F.Scale)); | |||||||||
4520 | Ops.push_back(ScaledS); | |||||||||
4521 | } | |||||||||
4522 | } | |||||||||
4523 | ||||||||||
4524 | // Expand the GV portion. | |||||||||
4525 | if (F.BaseGV) { | |||||||||
4526 | // Flush the operand list to suppress SCEVExpander hoisting. | |||||||||
4527 | if (!Ops.empty()) { | |||||||||
4528 | Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty); | |||||||||
4529 | Ops.clear(); | |||||||||
4530 | Ops.push_back(SE.getUnknown(FullV)); | |||||||||
4531 | } | |||||||||
4532 | Ops.push_back(SE.getUnknown(F.BaseGV)); | |||||||||
4533 | } | |||||||||
4534 | ||||||||||
4535 | // Flush the operand list to suppress SCEVExpander hoisting of both folded and | |||||||||
4536 | // unfolded offsets. LSR assumes they both live next to their uses. | |||||||||
4537 | if (!Ops.empty()) { | |||||||||
4538 | Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty); | |||||||||
4539 | Ops.clear(); | |||||||||
4540 | Ops.push_back(SE.getUnknown(FullV)); | |||||||||
4541 | } | |||||||||
4542 | ||||||||||
4543 | // Expand the immediate portion. | |||||||||
4544 | int64_t Offset = (uint64_t)F.BaseOffset + LF.Offset; | |||||||||
4545 | if (Offset != 0) { | |||||||||
4546 | if (LU.Kind == LSRUse::ICmpZero) { | |||||||||
4547 | // The other interesting way of "folding" with an ICmpZero is to use a | |||||||||
4548 | // negated immediate. | |||||||||
4549 | if (!ICmpScaledV) | |||||||||
4550 | ICmpScaledV = ConstantInt::get(IntTy, -(uint64_t)Offset); | |||||||||
4551 | else { | |||||||||
4552 | Ops.push_back(SE.getUnknown(ICmpScaledV)); | |||||||||
4553 | ICmpScaledV = ConstantInt::get(IntTy, Offset); | |||||||||
4554 | } | |||||||||
4555 | } else { | |||||||||
4556 | // Just add the immediate values. These again are expected to be matched | |||||||||
4557 | // as part of the address. | |||||||||
4558 | Ops.push_back(SE.getUnknown(ConstantInt::getSigned(IntTy, Offset))); | |||||||||
4559 | } | |||||||||
4560 | } | |||||||||
4561 | ||||||||||
4562 | // Expand the unfolded offset portion. | |||||||||
4563 | int64_t UnfoldedOffset = F.UnfoldedOffset; | |||||||||
4564 | if (UnfoldedOffset != 0) { | |||||||||
4565 | // Just add the immediate values. | |||||||||
4566 | Ops.push_back(SE.getUnknown(ConstantInt::getSigned(IntTy, | |||||||||
4567 | UnfoldedOffset))); | |||||||||
4568 | } | |||||||||
4569 | ||||||||||
4570 | // Emit instructions summing all the operands. | |||||||||
4571 | const SCEV *FullS = Ops.empty() ? | |||||||||
4572 | SE.getConstant(IntTy, 0) : | |||||||||
4573 | SE.getAddExpr(Ops); | |||||||||
4574 | Value *FullV = Rewriter.expandCodeFor(FullS, Ty); | |||||||||
4575 | ||||||||||
4576 | // We're done expanding now, so reset the rewriter. | |||||||||
4577 | Rewriter.clearPostInc(); | |||||||||
4578 | ||||||||||
4579 | // An ICmpZero Formula represents an ICmp which we're handling as a | |||||||||
4580 | // comparison against zero. Now that we've expanded an expression for that | |||||||||
4581 | // form, update the ICmp's other operand. | |||||||||
4582 | if (LU.Kind == LSRUse::ICmpZero) { | |||||||||
4583 | ICmpInst *CI = cast<ICmpInst>(LF.UserInst); | |||||||||
4584 | DeadInsts.emplace_back(CI->getOperand(1)); | |||||||||
4585 | assert(!F.BaseGV && "ICmp does not support folding a global value and "((!F.BaseGV && "ICmp does not support folding a global value and " "a scale at the same time!") ? static_cast<void> (0) : __assert_fail ("!F.BaseGV && \"ICmp does not support folding a global value and \" \"a scale at the same time!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4586, __PRETTY_FUNCTION__)) | |||||||||
4586 | "a scale at the same time!")((!F.BaseGV && "ICmp does not support folding a global value and " "a scale at the same time!") ? static_cast<void> (0) : __assert_fail ("!F.BaseGV && \"ICmp does not support folding a global value and \" \"a scale at the same time!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4586, __PRETTY_FUNCTION__)); | |||||||||
4587 | if (F.Scale == -1) { | |||||||||
4588 | if (ICmpScaledV->getType() != OpTy) { | |||||||||
4589 | Instruction *Cast = | |||||||||
4590 | CastInst::Create(CastInst::getCastOpcode(ICmpScaledV, false, | |||||||||
4591 | OpTy, false), | |||||||||
4592 | ICmpScaledV, OpTy, "tmp", CI); | |||||||||
4593 | ICmpScaledV = Cast; | |||||||||
4594 | } | |||||||||
4595 | CI->setOperand(1, ICmpScaledV); | |||||||||
4596 | } else { | |||||||||
4597 | // A scale of 1 means that the scale has been expanded as part of the | |||||||||
4598 | // base regs. | |||||||||
4599 | assert((F.Scale == 0 || F.Scale == 1) &&(((F.Scale == 0 || F.Scale == 1) && "ICmp does not support folding a global value and " "a scale at the same time!") ? static_cast<void> (0) : __assert_fail ("(F.Scale == 0 || F.Scale == 1) && \"ICmp does not support folding a global value and \" \"a scale at the same time!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4601, __PRETTY_FUNCTION__)) | |||||||||
4600 | "ICmp does not support folding a global value and "(((F.Scale == 0 || F.Scale == 1) && "ICmp does not support folding a global value and " "a scale at the same time!") ? static_cast<void> (0) : __assert_fail ("(F.Scale == 0 || F.Scale == 1) && \"ICmp does not support folding a global value and \" \"a scale at the same time!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4601, __PRETTY_FUNCTION__)) | |||||||||
4601 | "a scale at the same time!")(((F.Scale == 0 || F.Scale == 1) && "ICmp does not support folding a global value and " "a scale at the same time!") ? static_cast<void> (0) : __assert_fail ("(F.Scale == 0 || F.Scale == 1) && \"ICmp does not support folding a global value and \" \"a scale at the same time!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4601, __PRETTY_FUNCTION__)); | |||||||||
4602 | Constant *C = ConstantInt::getSigned(SE.getEffectiveSCEVType(OpTy), | |||||||||
4603 | -(uint64_t)Offset); | |||||||||
4604 | if (C->getType() != OpTy) | |||||||||
4605 | C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, | |||||||||
4606 | OpTy, false), | |||||||||
4607 | C, OpTy); | |||||||||
4608 | ||||||||||
4609 | CI->setOperand(1, C); | |||||||||
4610 | } | |||||||||
4611 | } | |||||||||
4612 | ||||||||||
4613 | return FullV; | |||||||||
4614 | } | |||||||||
4615 | ||||||||||
4616 | /// Helper for Rewrite. PHI nodes are special because the use of their operands | |||||||||
4617 | /// effectively happens in their predecessor blocks, so the expression may need | |||||||||
4618 | /// to be expanded in multiple places. | |||||||||
4619 | void LSRInstance::RewriteForPHI(PHINode *PN, | |||||||||
4620 | const LSRUse &LU, | |||||||||
4621 | const LSRFixup &LF, | |||||||||
4622 | const Formula &F, | |||||||||
4623 | SCEVExpander &Rewriter, | |||||||||
4624 | SmallVectorImpl<WeakVH> &DeadInsts) const { | |||||||||
4625 | DenseMap<BasicBlock *, Value *> Inserted; | |||||||||
4626 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) | |||||||||
4627 | if (PN->getIncomingValue(i) == LF.OperandValToReplace) { | |||||||||
4628 | BasicBlock *BB = PN->getIncomingBlock(i); | |||||||||
4629 | ||||||||||
4630 | // If this is a critical edge, split the edge so that we do not insert | |||||||||
4631 | // the code on all predecessor/successor paths. We do this unless this | |||||||||
4632 | // is the canonical backedge for this loop, which complicates post-inc | |||||||||
4633 | // users. | |||||||||
4634 | if (e != 1 && BB->getTerminator()->getNumSuccessors() > 1 && | |||||||||
4635 | !isa<IndirectBrInst>(BB->getTerminator())) { | |||||||||
4636 | BasicBlock *Parent = PN->getParent(); | |||||||||
4637 | Loop *PNLoop = LI.getLoopFor(Parent); | |||||||||
4638 | if (!PNLoop || Parent != PNLoop->getHeader()) { | |||||||||
4639 | // Split the critical edge. | |||||||||
4640 | BasicBlock *NewBB = nullptr; | |||||||||
4641 | if (!Parent->isLandingPad()) { | |||||||||
4642 | NewBB = SplitCriticalEdge(BB, Parent, | |||||||||
4643 | CriticalEdgeSplittingOptions(&DT, &LI) | |||||||||
4644 | .setMergeIdenticalEdges() | |||||||||
4645 | .setDontDeleteUselessPHIs()); | |||||||||
4646 | } else { | |||||||||
4647 | SmallVector<BasicBlock*, 2> NewBBs; | |||||||||
4648 | SplitLandingPadPredecessors(Parent, BB, "", "", NewBBs, &DT, &LI); | |||||||||
4649 | NewBB = NewBBs[0]; | |||||||||
4650 | } | |||||||||
4651 | // If NewBB==NULL, then SplitCriticalEdge refused to split because all | |||||||||
4652 | // phi predecessors are identical. The simple thing to do is skip | |||||||||
4653 | // splitting in this case rather than complicate the API. | |||||||||
4654 | if (NewBB) { | |||||||||
4655 | // If PN is outside of the loop and BB is in the loop, we want to | |||||||||
4656 | // move the block to be immediately before the PHI block, not | |||||||||
4657 | // immediately after BB. | |||||||||
4658 | if (L->contains(BB) && !L->contains(PN)) | |||||||||
4659 | NewBB->moveBefore(PN->getParent()); | |||||||||
4660 | ||||||||||
4661 | // Splitting the edge can reduce the number of PHI entries we have. | |||||||||
4662 | e = PN->getNumIncomingValues(); | |||||||||
4663 | BB = NewBB; | |||||||||
4664 | i = PN->getBasicBlockIndex(BB); | |||||||||
4665 | } | |||||||||
4666 | } | |||||||||
4667 | } | |||||||||
4668 | ||||||||||
4669 | std::pair<DenseMap<BasicBlock *, Value *>::iterator, bool> Pair = | |||||||||
4670 | Inserted.insert(std::make_pair(BB, static_cast<Value *>(nullptr))); | |||||||||
4671 | if (!Pair.second) | |||||||||
4672 | PN->setIncomingValue(i, Pair.first->second); | |||||||||
4673 | else { | |||||||||
4674 | Value *FullV = Expand(LU, LF, F, BB->getTerminator()->getIterator(), | |||||||||
4675 | Rewriter, DeadInsts); | |||||||||
4676 | ||||||||||
4677 | // If this is reuse-by-noop-cast, insert the noop cast. | |||||||||
4678 | Type *OpTy = LF.OperandValToReplace->getType(); | |||||||||
4679 | if (FullV->getType() != OpTy) | |||||||||
4680 | FullV = | |||||||||
4681 | CastInst::Create(CastInst::getCastOpcode(FullV, false, | |||||||||
4682 | OpTy, false), | |||||||||
4683 | FullV, LF.OperandValToReplace->getType(), | |||||||||
4684 | "tmp", BB->getTerminator()); | |||||||||
4685 | ||||||||||
4686 | PN->setIncomingValue(i, FullV); | |||||||||
4687 | Pair.first->second = FullV; | |||||||||
4688 | } | |||||||||
4689 | } | |||||||||
4690 | } | |||||||||
4691 | ||||||||||
4692 | /// Emit instructions for the leading candidate expression for this LSRUse (this | |||||||||
4693 | /// is called "expanding"), and update the UserInst to reference the newly | |||||||||
4694 | /// expanded value. | |||||||||
4695 | void LSRInstance::Rewrite(const LSRUse &LU, | |||||||||
4696 | const LSRFixup &LF, | |||||||||
4697 | const Formula &F, | |||||||||
4698 | SCEVExpander &Rewriter, | |||||||||
4699 | SmallVectorImpl<WeakVH> &DeadInsts) const { | |||||||||
4700 | // First, find an insertion point that dominates UserInst. For PHI nodes, | |||||||||
4701 | // find the nearest block which dominates all the relevant uses. | |||||||||
4702 | if (PHINode *PN = dyn_cast<PHINode>(LF.UserInst)) { | |||||||||
4703 | RewriteForPHI(PN, LU, LF, F, Rewriter, DeadInsts); | |||||||||
4704 | } else { | |||||||||
4705 | Value *FullV = | |||||||||
4706 | Expand(LU, LF, F, LF.UserInst->getIterator(), Rewriter, DeadInsts); | |||||||||
4707 | ||||||||||
4708 | // If this is reuse-by-noop-cast, insert the noop cast. | |||||||||
4709 | Type *OpTy = LF.OperandValToReplace->getType(); | |||||||||
4710 | if (FullV->getType() != OpTy) { | |||||||||
4711 | Instruction *Cast = | |||||||||
4712 | CastInst::Create(CastInst::getCastOpcode(FullV, false, OpTy, false), | |||||||||
4713 | FullV, OpTy, "tmp", LF.UserInst); | |||||||||
4714 | FullV = Cast; | |||||||||
4715 | } | |||||||||
4716 | ||||||||||
4717 | // Update the user. ICmpZero is handled specially here (for now) because | |||||||||
4718 | // Expand may have updated one of the operands of the icmp already, and | |||||||||
4719 | // its new value may happen to be equal to LF.OperandValToReplace, in | |||||||||
4720 | // which case doing replaceUsesOfWith leads to replacing both operands | |||||||||
4721 | // with the same value. TODO: Reorganize this. | |||||||||
4722 | if (LU.Kind == LSRUse::ICmpZero) | |||||||||
4723 | LF.UserInst->setOperand(0, FullV); | |||||||||
4724 | else | |||||||||
4725 | LF.UserInst->replaceUsesOfWith(LF.OperandValToReplace, FullV); | |||||||||
4726 | } | |||||||||
4727 | ||||||||||
4728 | DeadInsts.emplace_back(LF.OperandValToReplace); | |||||||||
4729 | } | |||||||||
4730 | ||||||||||
4731 | /// Rewrite all the fixup locations with new values, following the chosen | |||||||||
4732 | /// solution. | |||||||||
4733 | void LSRInstance::ImplementSolution( | |||||||||
4734 | const SmallVectorImpl<const Formula *> &Solution) { | |||||||||
4735 | // Keep track of instructions we may have made dead, so that | |||||||||
4736 | // we can remove them after we are done working. | |||||||||
4737 | SmallVector<WeakVH, 16> DeadInsts; | |||||||||
4738 | ||||||||||
4739 | SCEVExpander Rewriter(SE, L->getHeader()->getModule()->getDataLayout(), | |||||||||
4740 | "lsr"); | |||||||||
4741 | #ifndef NDEBUG | |||||||||
4742 | Rewriter.setDebugType(DEBUG_TYPE"loop-reduce"); | |||||||||
4743 | #endif | |||||||||
4744 | Rewriter.disableCanonicalMode(); | |||||||||
4745 | Rewriter.enableLSRMode(); | |||||||||
4746 | Rewriter.setIVIncInsertPos(L, IVIncInsertPos); | |||||||||
4747 | ||||||||||
4748 | // Mark phi nodes that terminate chains so the expander tries to reuse them. | |||||||||
4749 | for (const IVChain &Chain : IVChainVec) { | |||||||||
4750 | if (PHINode *PN = dyn_cast<PHINode>(Chain.tailUserInst())) | |||||||||
4751 | Rewriter.setChainedPhi(PN); | |||||||||
4752 | } | |||||||||
4753 | ||||||||||
4754 | // Expand the new value definitions and update the users. | |||||||||
4755 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) | |||||||||
4756 | for (const LSRFixup &Fixup : Uses[LUIdx].Fixups) { | |||||||||
4757 | Rewrite(Uses[LUIdx], Fixup, *Solution[LUIdx], Rewriter, DeadInsts); | |||||||||
4758 | Changed = true; | |||||||||
4759 | } | |||||||||
4760 | ||||||||||
4761 | for (const IVChain &Chain : IVChainVec) { | |||||||||
4762 | GenerateIVChain(Chain, Rewriter, DeadInsts); | |||||||||
4763 | Changed = true; | |||||||||
4764 | } | |||||||||
4765 | // Clean up after ourselves. This must be done before deleting any | |||||||||
4766 | // instructions. | |||||||||
4767 | Rewriter.clear(); | |||||||||
4768 | ||||||||||
4769 | Changed |= DeleteTriviallyDeadInstructions(DeadInsts); | |||||||||
4770 | } | |||||||||
4771 | ||||||||||
4772 | LSRInstance::LSRInstance(Loop *L, IVUsers &IU, ScalarEvolution &SE, | |||||||||
4773 | DominatorTree &DT, LoopInfo &LI, | |||||||||
4774 | const TargetTransformInfo &TTI) | |||||||||
4775 | : IU(IU), SE(SE), DT(DT), LI(LI), TTI(TTI), L(L), Changed(false), | |||||||||
4776 | IVIncInsertPos(nullptr) { | |||||||||
4777 | // If LoopSimplify form is not available, stay out of trouble. | |||||||||
4778 | if (!L->isLoopSimplifyForm()) | |||||||||
4779 | return; | |||||||||
4780 | ||||||||||
4781 | // If there's no interesting work to be done, bail early. | |||||||||
4782 | if (IU.empty()) return; | |||||||||
4783 | ||||||||||
4784 | // If there's too much analysis to be done, bail early. We won't be able to | |||||||||
4785 | // model the problem anyway. | |||||||||
4786 | unsigned NumUsers = 0; | |||||||||
4787 | for (const IVStrideUse &U : IU) { | |||||||||
4788 | if (++NumUsers > MaxIVUsers) { | |||||||||
4789 | (void)U; | |||||||||
4790 | DEBUG(dbgs() << "LSR skipping loop, too many IV Users in " << U << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "LSR skipping loop, too many IV Users in " << U << "\n"; } } while (false); | |||||||||
4791 | return; | |||||||||
4792 | } | |||||||||
4793 | // Bail out if we have a PHI on an EHPad that gets a value from a | |||||||||
4794 | // CatchSwitchInst. Because the CatchSwitchInst cannot be split, there is | |||||||||
4795 | // no good place to stick any instructions. | |||||||||
4796 | if (auto *PN = dyn_cast<PHINode>(U.getUser())) { | |||||||||
4797 | auto *FirstNonPHI = PN->getParent()->getFirstNonPHI(); | |||||||||
4798 | if (isa<FuncletPadInst>(FirstNonPHI) || | |||||||||
4799 | isa<CatchSwitchInst>(FirstNonPHI)) | |||||||||
4800 | for (BasicBlock *PredBB : PN->blocks()) | |||||||||
4801 | if (isa<CatchSwitchInst>(PredBB->getFirstNonPHI())) | |||||||||
4802 | return; | |||||||||
4803 | } | |||||||||
4804 | } | |||||||||
4805 | ||||||||||
4806 | #ifndef NDEBUG | |||||||||
4807 | // All dominating loops must have preheaders, or SCEVExpander may not be able | |||||||||
4808 | // to materialize an AddRecExpr whose Start is an outer AddRecExpr. | |||||||||
4809 | // | |||||||||
4810 | // IVUsers analysis should only create users that are dominated by simple loop | |||||||||
4811 | // headers. Since this loop should dominate all of its users, its user list | |||||||||
4812 | // should be empty if this loop itself is not within a simple loop nest. | |||||||||
4813 | for (DomTreeNode *Rung = DT.getNode(L->getLoopPreheader()); | |||||||||
4814 | Rung; Rung = Rung->getIDom()) { | |||||||||
4815 | BasicBlock *BB = Rung->getBlock(); | |||||||||
4816 | const Loop *DomLoop = LI.getLoopFor(BB); | |||||||||
4817 | if (DomLoop && DomLoop->getHeader() == BB) { | |||||||||
4818 | assert(DomLoop->getLoopPreheader() && "LSR needs a simplified loop nest")((DomLoop->getLoopPreheader() && "LSR needs a simplified loop nest" ) ? static_cast<void> (0) : __assert_fail ("DomLoop->getLoopPreheader() && \"LSR needs a simplified loop nest\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4818, __PRETTY_FUNCTION__)); | |||||||||
4819 | } | |||||||||
4820 | } | |||||||||
4821 | #endif // DEBUG | |||||||||
4822 | ||||||||||
4823 | DEBUG(dbgs() << "\nLSR on loop ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\nLSR on loop "; L->getHeader ()->printAsOperand(dbgs(), false); dbgs() << ":\n"; } } while (false) | |||||||||
4824 | L->getHeader()->printAsOperand(dbgs(), /*PrintType=*/false);do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\nLSR on loop "; L->getHeader ()->printAsOperand(dbgs(), false); dbgs() << ":\n"; } } while (false) | |||||||||
4825 | dbgs() << ":\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\nLSR on loop "; L->getHeader ()->printAsOperand(dbgs(), false); dbgs() << ":\n"; } } while (false); | |||||||||
4826 | ||||||||||
4827 | // First, perform some low-level loop optimizations. | |||||||||
4828 | OptimizeShadowIV(); | |||||||||
4829 | OptimizeLoopTermCond(); | |||||||||
4830 | ||||||||||
4831 | // If loop preparation eliminates all interesting IV users, bail. | |||||||||
4832 | if (IU.empty()) return; | |||||||||
4833 | ||||||||||
4834 | // Skip nested loops until we can model them better with formulae. | |||||||||
4835 | if (!L->empty()) { | |||||||||
4836 | DEBUG(dbgs() << "LSR skipping outer loop " << *L << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "LSR skipping outer loop " << *L << "\n"; } } while (false); | |||||||||
4837 | return; | |||||||||
4838 | } | |||||||||
4839 | ||||||||||
4840 | // Start collecting data and preparing for the solver. | |||||||||
4841 | CollectChains(); | |||||||||
4842 | CollectInterestingTypesAndFactors(); | |||||||||
4843 | CollectFixupsAndInitialFormulae(); | |||||||||
4844 | CollectLoopInvariantFixupsAndFormulae(); | |||||||||
4845 | ||||||||||
4846 | assert(!Uses.empty() && "IVUsers reported at least one use")((!Uses.empty() && "IVUsers reported at least one use" ) ? static_cast<void> (0) : __assert_fail ("!Uses.empty() && \"IVUsers reported at least one use\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4846, __PRETTY_FUNCTION__)); | |||||||||
4847 | DEBUG(dbgs() << "LSR found " << Uses.size() << " uses:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "LSR found " << Uses .size() << " uses:\n"; print_uses(dbgs()); } } while (false ) | |||||||||
4848 | print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "LSR found " << Uses .size() << " uses:\n"; print_uses(dbgs()); } } while (false ); | |||||||||
4849 | ||||||||||
4850 | // Now use the reuse data to generate a bunch of interesting ways | |||||||||
4851 | // to formulate the values needed for the uses. | |||||||||
4852 | GenerateAllReuseFormulae(); | |||||||||
4853 | ||||||||||
4854 | FilterOutUndesirableDedicatedRegisters(); | |||||||||
4855 | NarrowSearchSpaceUsingHeuristics(); | |||||||||
4856 | ||||||||||
4857 | SmallVector<const Formula *, 8> Solution; | |||||||||
4858 | Solve(Solution); | |||||||||
4859 | ||||||||||
4860 | // Release memory that is no longer needed. | |||||||||
4861 | Factors.clear(); | |||||||||
4862 | Types.clear(); | |||||||||
4863 | RegUses.clear(); | |||||||||
4864 | ||||||||||
4865 | if (Solution.empty()) | |||||||||
4866 | return; | |||||||||
4867 | ||||||||||
4868 | #ifndef NDEBUG | |||||||||
4869 | // Formulae should be legal. | |||||||||
4870 | for (const LSRUse &LU : Uses) { | |||||||||
4871 | for (const Formula &F : LU.Formulae) | |||||||||
4872 | assert(isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy,((isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy , F) && "Illegal formula generated!") ? static_cast< void> (0) : __assert_fail ("isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) && \"Illegal formula generated!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4873, __PRETTY_FUNCTION__)) | |||||||||
4873 | F) && "Illegal formula generated!")((isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy , F) && "Illegal formula generated!") ? static_cast< void> (0) : __assert_fail ("isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) && \"Illegal formula generated!\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4873, __PRETTY_FUNCTION__)); | |||||||||
4874 | }; | |||||||||
4875 | #endif | |||||||||
4876 | ||||||||||
4877 | // Now that we've decided what we want, make it so. | |||||||||
4878 | ImplementSolution(Solution); | |||||||||
4879 | } | |||||||||
4880 | ||||||||||
4881 | void LSRInstance::print_factors_and_types(raw_ostream &OS) const { | |||||||||
4882 | if (Factors.empty() && Types.empty()) return; | |||||||||
4883 | ||||||||||
4884 | OS << "LSR has identified the following interesting factors and types: "; | |||||||||
4885 | bool First = true; | |||||||||
4886 | ||||||||||
4887 | for (int64_t Factor : Factors) { | |||||||||
4888 | if (!First) OS << ", "; | |||||||||
4889 | First = false; | |||||||||
4890 | OS << '*' << Factor; | |||||||||
4891 | } | |||||||||
4892 | ||||||||||
4893 | for (Type *Ty : Types) { | |||||||||
4894 | if (!First) OS << ", "; | |||||||||
4895 | First = false; | |||||||||
4896 | OS << '(' << *Ty << ')'; | |||||||||
4897 | } | |||||||||
4898 | OS << '\n'; | |||||||||
4899 | } | |||||||||
4900 | ||||||||||
4901 | void LSRInstance::print_fixups(raw_ostream &OS) const { | |||||||||
4902 | OS << "LSR is examining the following fixup sites:\n"; | |||||||||
4903 | for (const LSRUse &LU : Uses) | |||||||||
4904 | for (const LSRFixup &LF : LU.Fixups) { | |||||||||
4905 | dbgs() << " "; | |||||||||
4906 | LF.print(OS); | |||||||||
4907 | OS << '\n'; | |||||||||
4908 | } | |||||||||
4909 | } | |||||||||
4910 | ||||||||||
4911 | void LSRInstance::print_uses(raw_ostream &OS) const { | |||||||||
4912 | OS << "LSR is examining the following uses:\n"; | |||||||||
4913 | for (const LSRUse &LU : Uses) { | |||||||||
4914 | dbgs() << " "; | |||||||||
4915 | LU.print(OS); | |||||||||
4916 | OS << '\n'; | |||||||||
4917 | for (const Formula &F : LU.Formulae) { | |||||||||
4918 | OS << " "; | |||||||||
4919 | F.print(OS); | |||||||||
4920 | OS << '\n'; | |||||||||
4921 | } | |||||||||
4922 | } | |||||||||
4923 | } | |||||||||
4924 | ||||||||||
4925 | void LSRInstance::print(raw_ostream &OS) const { | |||||||||
4926 | print_factors_and_types(OS); | |||||||||
4927 | print_fixups(OS); | |||||||||
4928 | print_uses(OS); | |||||||||
4929 | } | |||||||||
4930 | ||||||||||
4931 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) | |||||||||
4932 | void LSRInstance::dump() const { | |||||||||
4933 | print(errs()); errs() << '\n'; | |||||||||
4934 | } | |||||||||
4935 | ||||||||||
4936 | namespace { | |||||||||
4937 | ||||||||||
4938 | class LoopStrengthReduce : public LoopPass { | |||||||||
4939 | public: | |||||||||
4940 | static char ID; // Pass ID, replacement for typeid | |||||||||
4941 | LoopStrengthReduce(); | |||||||||
4942 | ||||||||||
4943 | private: | |||||||||
4944 | bool runOnLoop(Loop *L, LPPassManager &LPM) override; | |||||||||
4945 | void getAnalysisUsage(AnalysisUsage &AU) const override; | |||||||||
4946 | }; | |||||||||
4947 | } | |||||||||
4948 | ||||||||||
4949 | char LoopStrengthReduce::ID = 0; | |||||||||
4950 | INITIALIZE_PASS_BEGIN(LoopStrengthReduce, "loop-reduce",static void *initializeLoopStrengthReducePassOnce(PassRegistry &Registry) { | |||||||||
4951 | "Loop Strength Reduction", false, false)static void *initializeLoopStrengthReducePassOnce(PassRegistry &Registry) { | |||||||||
4952 | INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)initializeTargetTransformInfoWrapperPassPass(Registry); | |||||||||
4953 | INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry); | |||||||||
4954 | INITIALIZE_PASS_DEPENDENCY(ScalarEvolutionWrapperPass)initializeScalarEvolutionWrapperPassPass(Registry); | |||||||||
4955 | INITIALIZE_PASS_DEPENDENCY(IVUsersWrapperPass)initializeIVUsersWrapperPassPass(Registry); | |||||||||
4956 | INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)initializeLoopInfoWrapperPassPass(Registry); | |||||||||
4957 | INITIALIZE_PASS_DEPENDENCY(LoopSimplify)initializeLoopSimplifyPass(Registry); | |||||||||
4958 | INITIALIZE_PASS_END(LoopStrengthReduce, "loop-reduce",PassInfo *PI = new PassInfo( "Loop Strength Reduction", "loop-reduce" , &LoopStrengthReduce::ID, PassInfo::NormalCtor_t(callDefaultCtor <LoopStrengthReduce>), false, false); Registry.registerPass (*PI, true); return PI; } static once_flag InitializeLoopStrengthReducePassFlag ; void llvm::initializeLoopStrengthReducePass(PassRegistry & Registry) { llvm::call_once(InitializeLoopStrengthReducePassFlag , initializeLoopStrengthReducePassOnce, std::ref(Registry)); } | |||||||||
4959 | "Loop Strength Reduction", false, false)PassInfo *PI = new PassInfo( "Loop Strength Reduction", "loop-reduce" , &LoopStrengthReduce::ID, PassInfo::NormalCtor_t(callDefaultCtor <LoopStrengthReduce>), false, false); Registry.registerPass (*PI, true); return PI; } static once_flag InitializeLoopStrengthReducePassFlag ; void llvm::initializeLoopStrengthReducePass(PassRegistry & Registry) { llvm::call_once(InitializeLoopStrengthReducePassFlag , initializeLoopStrengthReducePassOnce, std::ref(Registry)); } | |||||||||
4960 | ||||||||||
4961 | Pass *llvm::createLoopStrengthReducePass() { return new LoopStrengthReduce(); } | |||||||||
4962 | ||||||||||
4963 | LoopStrengthReduce::LoopStrengthReduce() : LoopPass(ID) { | |||||||||
4964 | initializeLoopStrengthReducePass(*PassRegistry::getPassRegistry()); | |||||||||
4965 | } | |||||||||
4966 | ||||||||||
4967 | void LoopStrengthReduce::getAnalysisUsage(AnalysisUsage &AU) const { | |||||||||
4968 | // We split critical edges, so we change the CFG. However, we do update | |||||||||
4969 | // many analyses if they are around. | |||||||||
4970 | AU.addPreservedID(LoopSimplifyID); | |||||||||
4971 | ||||||||||
4972 | AU.addRequired<LoopInfoWrapperPass>(); | |||||||||
4973 | AU.addPreserved<LoopInfoWrapperPass>(); | |||||||||
4974 | AU.addRequiredID(LoopSimplifyID); | |||||||||
4975 | AU.addRequired<DominatorTreeWrapperPass>(); | |||||||||
4976 | AU.addPreserved<DominatorTreeWrapperPass>(); | |||||||||
4977 | AU.addRequired<ScalarEvolutionWrapperPass>(); | |||||||||
4978 | AU.addPreserved<ScalarEvolutionWrapperPass>(); | |||||||||
4979 | // Requiring LoopSimplify a second time here prevents IVUsers from running | |||||||||
4980 | // twice, since LoopSimplify was invalidated by running ScalarEvolution. | |||||||||
4981 | AU.addRequiredID(LoopSimplifyID); | |||||||||
4982 | AU.addRequired<IVUsersWrapperPass>(); | |||||||||
4983 | AU.addPreserved<IVUsersWrapperPass>(); | |||||||||
4984 | AU.addRequired<TargetTransformInfoWrapperPass>(); | |||||||||
4985 | } | |||||||||
4986 | ||||||||||
4987 | static bool ReduceLoopStrength(Loop *L, IVUsers &IU, ScalarEvolution &SE, | |||||||||
4988 | DominatorTree &DT, LoopInfo &LI, | |||||||||
4989 | const TargetTransformInfo &TTI) { | |||||||||
4990 | bool Changed = false; | |||||||||
4991 | ||||||||||
4992 | // Run the main LSR transformation. | |||||||||
4993 | Changed |= LSRInstance(L, IU, SE, DT, LI, TTI).getChanged(); | |||||||||
4994 | ||||||||||
4995 | // Remove any extra phis created by processing inner loops. | |||||||||
4996 | Changed |= DeleteDeadPHIs(L->getHeader()); | |||||||||
4997 | if (EnablePhiElim && L->isLoopSimplifyForm()) { | |||||||||
4998 | SmallVector<WeakVH, 16> DeadInsts; | |||||||||
4999 | const DataLayout &DL = L->getHeader()->getModule()->getDataLayout(); | |||||||||
5000 | SCEVExpander Rewriter(SE, DL, "lsr"); | |||||||||
5001 | #ifndef NDEBUG | |||||||||
5002 | Rewriter.setDebugType(DEBUG_TYPE"loop-reduce"); | |||||||||
5003 | #endif | |||||||||
5004 | unsigned numFolded = Rewriter.replaceCongruentIVs(L, &DT, DeadInsts, &TTI); | |||||||||
5005 | if (numFolded) { | |||||||||
5006 | Changed = true; | |||||||||
5007 | DeleteTriviallyDeadInstructions(DeadInsts); | |||||||||
5008 | DeleteDeadPHIs(L->getHeader()); | |||||||||
5009 | } | |||||||||
5010 | } | |||||||||
5011 | return Changed; | |||||||||
5012 | } | |||||||||
5013 | ||||||||||
5014 | bool LoopStrengthReduce::runOnLoop(Loop *L, LPPassManager & /*LPM*/) { | |||||||||
5015 | if (skipLoop(L)) | |||||||||
5016 | return false; | |||||||||
5017 | ||||||||||
5018 | auto &IU = getAnalysis<IVUsersWrapperPass>().getIU(); | |||||||||
5019 | auto &SE = getAnalysis<ScalarEvolutionWrapperPass>().getSE(); | |||||||||
5020 | auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree(); | |||||||||
5021 | auto &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo(); | |||||||||
5022 | const auto &TTI = getAnalysis<TargetTransformInfoWrapperPass>().getTTI( | |||||||||
5023 | *L->getHeader()->getParent()); | |||||||||
5024 | return ReduceLoopStrength(L, IU, SE, DT, LI, TTI); | |||||||||
5025 | } | |||||||||
5026 | ||||||||||
5027 | PreservedAnalyses LoopStrengthReducePass::run(Loop &L, | |||||||||
5028 | LoopAnalysisManager &AM) { | |||||||||
5029 | const auto &FAM = | |||||||||
5030 | AM.getResult<FunctionAnalysisManagerLoopProxy>(L).getManager(); | |||||||||
5031 | Function *F = L.getHeader()->getParent(); | |||||||||
5032 | ||||||||||
5033 | auto &IU = AM.getResult<IVUsersAnalysis>(L); | |||||||||
5034 | auto *SE = FAM.getCachedResult<ScalarEvolutionAnalysis>(*F); | |||||||||
5035 | auto *DT = FAM.getCachedResult<DominatorTreeAnalysis>(*F); | |||||||||
5036 | auto *LI = FAM.getCachedResult<LoopAnalysis>(*F); | |||||||||
5037 | auto *TTI = FAM.getCachedResult<TargetIRAnalysis>(*F); | |||||||||
5038 | assert((SE && DT && LI && TTI) &&(((SE && DT && LI && TTI) && "Analyses for Loop Strength Reduce not available" ) ? static_cast<void> (0) : __assert_fail ("(SE && DT && LI && TTI) && \"Analyses for Loop Strength Reduce not available\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 5039, __PRETTY_FUNCTION__)) | |||||||||
5039 | "Analyses for Loop Strength Reduce not available")(((SE && DT && LI && TTI) && "Analyses for Loop Strength Reduce not available" ) ? static_cast<void> (0) : __assert_fail ("(SE && DT && LI && TTI) && \"Analyses for Loop Strength Reduce not available\"" , "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn285991/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 5039, __PRETTY_FUNCTION__)); | |||||||||
5040 | ||||||||||
5041 | if (!ReduceLoopStrength(&L, IU, *SE, *DT, *LI, *TTI)) | |||||||||
5042 | return PreservedAnalyses::all(); | |||||||||
5043 | ||||||||||
5044 | return getLoopPassPreservedAnalyses(); | |||||||||
5045 | } |