File: | lib/Transforms/Scalar/LoopStrengthReduce.cpp |
Warning: | line 5237, column 22 Called C++ object pointer is null |
Press '?' to see keyboard shortcuts
Keyboard shortcuts:
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/APInt.h" | |||
58 | #include "llvm/ADT/DenseMap.h" | |||
59 | #include "llvm/ADT/DenseSet.h" | |||
60 | #include "llvm/ADT/Hashing.h" | |||
61 | #include "llvm/ADT/PointerIntPair.h" | |||
62 | #include "llvm/ADT/STLExtras.h" | |||
63 | #include "llvm/ADT/SetVector.h" | |||
64 | #include "llvm/ADT/SmallBitVector.h" | |||
65 | #include "llvm/ADT/SmallPtrSet.h" | |||
66 | #include "llvm/ADT/SmallSet.h" | |||
67 | #include "llvm/ADT/SmallVector.h" | |||
68 | #include "llvm/ADT/iterator_range.h" | |||
69 | #include "llvm/Analysis/IVUsers.h" | |||
70 | #include "llvm/Analysis/LoopAnalysisManager.h" | |||
71 | #include "llvm/Analysis/LoopInfo.h" | |||
72 | #include "llvm/Analysis/LoopPass.h" | |||
73 | #include "llvm/Analysis/ScalarEvolution.h" | |||
74 | #include "llvm/Analysis/ScalarEvolutionExpander.h" | |||
75 | #include "llvm/Analysis/ScalarEvolutionExpressions.h" | |||
76 | #include "llvm/Analysis/ScalarEvolutionNormalization.h" | |||
77 | #include "llvm/Analysis/TargetTransformInfo.h" | |||
78 | #include "llvm/Transforms/Utils/Local.h" | |||
79 | #include "llvm/Config/llvm-config.h" | |||
80 | #include "llvm/IR/BasicBlock.h" | |||
81 | #include "llvm/IR/Constant.h" | |||
82 | #include "llvm/IR/Constants.h" | |||
83 | #include "llvm/IR/DerivedTypes.h" | |||
84 | #include "llvm/IR/Dominators.h" | |||
85 | #include "llvm/IR/GlobalValue.h" | |||
86 | #include "llvm/IR/IRBuilder.h" | |||
87 | #include "llvm/IR/InstrTypes.h" | |||
88 | #include "llvm/IR/Instruction.h" | |||
89 | #include "llvm/IR/Instructions.h" | |||
90 | #include "llvm/IR/IntrinsicInst.h" | |||
91 | #include "llvm/IR/Intrinsics.h" | |||
92 | #include "llvm/IR/Module.h" | |||
93 | #include "llvm/IR/OperandTraits.h" | |||
94 | #include "llvm/IR/Operator.h" | |||
95 | #include "llvm/IR/PassManager.h" | |||
96 | #include "llvm/IR/Type.h" | |||
97 | #include "llvm/IR/Use.h" | |||
98 | #include "llvm/IR/User.h" | |||
99 | #include "llvm/IR/Value.h" | |||
100 | #include "llvm/IR/ValueHandle.h" | |||
101 | #include "llvm/Pass.h" | |||
102 | #include "llvm/Support/Casting.h" | |||
103 | #include "llvm/Support/CommandLine.h" | |||
104 | #include "llvm/Support/Compiler.h" | |||
105 | #include "llvm/Support/Debug.h" | |||
106 | #include "llvm/Support/ErrorHandling.h" | |||
107 | #include "llvm/Support/MathExtras.h" | |||
108 | #include "llvm/Support/raw_ostream.h" | |||
109 | #include "llvm/Transforms/Scalar.h" | |||
110 | #include "llvm/Transforms/Utils.h" | |||
111 | #include "llvm/Transforms/Utils/BasicBlockUtils.h" | |||
112 | #include <algorithm> | |||
113 | #include <cassert> | |||
114 | #include <cstddef> | |||
115 | #include <cstdint> | |||
116 | #include <cstdlib> | |||
117 | #include <iterator> | |||
118 | #include <limits> | |||
119 | #include <map> | |||
120 | #include <utility> | |||
121 | ||||
122 | using namespace llvm; | |||
123 | ||||
124 | #define DEBUG_TYPE"loop-reduce" "loop-reduce" | |||
125 | ||||
126 | /// MaxIVUsers is an arbitrary threshold that provides an early opportunity for | |||
127 | /// bail out. This threshold is far beyond the number of users that LSR can | |||
128 | /// conceivably solve, so it should not affect generated code, but catches the | |||
129 | /// worst cases before LSR burns too much compile time and stack space. | |||
130 | static const unsigned MaxIVUsers = 200; | |||
131 | ||||
132 | // Temporary flag to cleanup congruent phis after LSR phi expansion. | |||
133 | // It's currently disabled until we can determine whether it's truly useful or | |||
134 | // not. The flag should be removed after the v3.0 release. | |||
135 | // This is now needed for ivchains. | |||
136 | static cl::opt<bool> EnablePhiElim( | |||
137 | "enable-lsr-phielim", cl::Hidden, cl::init(true), | |||
138 | cl::desc("Enable LSR phi elimination")); | |||
139 | ||||
140 | // The flag adds instruction count to solutions cost comparision. | |||
141 | static cl::opt<bool> InsnsCost( | |||
142 | "lsr-insns-cost", cl::Hidden, cl::init(true), | |||
143 | cl::desc("Add instruction count to a LSR cost model")); | |||
144 | ||||
145 | // Flag to choose how to narrow complex lsr solution | |||
146 | static cl::opt<bool> LSRExpNarrow( | |||
147 | "lsr-exp-narrow", cl::Hidden, cl::init(false), | |||
148 | cl::desc("Narrow LSR complex solution using" | |||
149 | " expectation of registers number")); | |||
150 | ||||
151 | // Flag to narrow search space by filtering non-optimal formulae with | |||
152 | // the same ScaledReg and Scale. | |||
153 | static cl::opt<bool> FilterSameScaledReg( | |||
154 | "lsr-filter-same-scaled-reg", cl::Hidden, cl::init(true), | |||
155 | cl::desc("Narrow LSR search space by filtering non-optimal formulae" | |||
156 | " with the same ScaledReg and Scale")); | |||
157 | ||||
158 | #ifndef NDEBUG | |||
159 | // Stress test IV chain generation. | |||
160 | static cl::opt<bool> StressIVChain( | |||
161 | "stress-ivchain", cl::Hidden, cl::init(false), | |||
162 | cl::desc("Stress test LSR IV chains")); | |||
163 | #else | |||
164 | static bool StressIVChain = false; | |||
165 | #endif | |||
166 | ||||
167 | namespace { | |||
168 | ||||
169 | struct MemAccessTy { | |||
170 | /// Used in situations where the accessed memory type is unknown. | |||
171 | static const unsigned UnknownAddressSpace = | |||
172 | std::numeric_limits<unsigned>::max(); | |||
173 | ||||
174 | Type *MemTy = nullptr; | |||
175 | unsigned AddrSpace = UnknownAddressSpace; | |||
176 | ||||
177 | MemAccessTy() = default; | |||
178 | MemAccessTy(Type *Ty, unsigned AS) : MemTy(Ty), AddrSpace(AS) {} | |||
179 | ||||
180 | bool operator==(MemAccessTy Other) const { | |||
181 | return MemTy == Other.MemTy && AddrSpace == Other.AddrSpace; | |||
182 | } | |||
183 | ||||
184 | bool operator!=(MemAccessTy Other) const { return !(*this == Other); } | |||
185 | ||||
186 | static MemAccessTy getUnknown(LLVMContext &Ctx, | |||
187 | unsigned AS = UnknownAddressSpace) { | |||
188 | return MemAccessTy(Type::getVoidTy(Ctx), AS); | |||
189 | } | |||
190 | ||||
191 | Type *getType() { return MemTy; } | |||
192 | }; | |||
193 | ||||
194 | /// This class holds data which is used to order reuse candidates. | |||
195 | class RegSortData { | |||
196 | public: | |||
197 | /// This represents the set of LSRUse indices which reference | |||
198 | /// a particular register. | |||
199 | SmallBitVector UsedByIndices; | |||
200 | ||||
201 | void print(raw_ostream &OS) const; | |||
202 | void dump() const; | |||
203 | }; | |||
204 | ||||
205 | } // end anonymous namespace | |||
206 | ||||
207 | #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) | |||
208 | void RegSortData::print(raw_ostream &OS) const { | |||
209 | OS << "[NumUses=" << UsedByIndices.count() << ']'; | |||
210 | } | |||
211 | ||||
212 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void RegSortData::dump() const { | |||
213 | print(errs()); errs() << '\n'; | |||
214 | } | |||
215 | #endif | |||
216 | ||||
217 | namespace { | |||
218 | ||||
219 | /// Map register candidates to information about how they are used. | |||
220 | class RegUseTracker { | |||
221 | using RegUsesTy = DenseMap<const SCEV *, RegSortData>; | |||
222 | ||||
223 | RegUsesTy RegUsesMap; | |||
224 | SmallVector<const SCEV *, 16> RegSequence; | |||
225 | ||||
226 | public: | |||
227 | void countRegister(const SCEV *Reg, size_t LUIdx); | |||
228 | void dropRegister(const SCEV *Reg, size_t LUIdx); | |||
229 | void swapAndDropUse(size_t LUIdx, size_t LastLUIdx); | |||
230 | ||||
231 | bool isRegUsedByUsesOtherThan(const SCEV *Reg, size_t LUIdx) const; | |||
232 | ||||
233 | const SmallBitVector &getUsedByIndices(const SCEV *Reg) const; | |||
234 | ||||
235 | void clear(); | |||
236 | ||||
237 | using iterator = SmallVectorImpl<const SCEV *>::iterator; | |||
238 | using const_iterator = SmallVectorImpl<const SCEV *>::const_iterator; | |||
239 | ||||
240 | iterator begin() { return RegSequence.begin(); } | |||
241 | iterator end() { return RegSequence.end(); } | |||
242 | const_iterator begin() const { return RegSequence.begin(); } | |||
243 | const_iterator end() const { return RegSequence.end(); } | |||
244 | }; | |||
245 | ||||
246 | } // end anonymous namespace | |||
247 | ||||
248 | void | |||
249 | RegUseTracker::countRegister(const SCEV *Reg, size_t LUIdx) { | |||
250 | std::pair<RegUsesTy::iterator, bool> Pair = | |||
251 | RegUsesMap.insert(std::make_pair(Reg, RegSortData())); | |||
252 | RegSortData &RSD = Pair.first->second; | |||
253 | if (Pair.second) | |||
254 | RegSequence.push_back(Reg); | |||
255 | RSD.UsedByIndices.resize(std::max(RSD.UsedByIndices.size(), LUIdx + 1)); | |||
256 | RSD.UsedByIndices.set(LUIdx); | |||
257 | } | |||
258 | ||||
259 | void | |||
260 | RegUseTracker::dropRegister(const SCEV *Reg, size_t LUIdx) { | |||
261 | RegUsesTy::iterator It = RegUsesMap.find(Reg); | |||
262 | assert(It != RegUsesMap.end())(static_cast <bool> (It != RegUsesMap.end()) ? void (0) : __assert_fail ("It != RegUsesMap.end()", "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 262, __extension__ __PRETTY_FUNCTION__)); | |||
263 | RegSortData &RSD = It->second; | |||
264 | assert(RSD.UsedByIndices.size() > LUIdx)(static_cast <bool> (RSD.UsedByIndices.size() > LUIdx ) ? void (0) : __assert_fail ("RSD.UsedByIndices.size() > LUIdx" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 264, __extension__ __PRETTY_FUNCTION__)); | |||
265 | RSD.UsedByIndices.reset(LUIdx); | |||
266 | } | |||
267 | ||||
268 | void | |||
269 | RegUseTracker::swapAndDropUse(size_t LUIdx, size_t LastLUIdx) { | |||
270 | assert(LUIdx <= LastLUIdx)(static_cast <bool> (LUIdx <= LastLUIdx) ? void (0) : __assert_fail ("LUIdx <= LastLUIdx", "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 270, __extension__ __PRETTY_FUNCTION__)); | |||
271 | ||||
272 | // Update RegUses. The data structure is not optimized for this purpose; | |||
273 | // we must iterate through it and update each of the bit vectors. | |||
274 | for (auto &Pair : RegUsesMap) { | |||
275 | SmallBitVector &UsedByIndices = Pair.second.UsedByIndices; | |||
276 | if (LUIdx < UsedByIndices.size()) | |||
277 | UsedByIndices[LUIdx] = | |||
278 | LastLUIdx < UsedByIndices.size() ? UsedByIndices[LastLUIdx] : false; | |||
279 | UsedByIndices.resize(std::min(UsedByIndices.size(), LastLUIdx)); | |||
280 | } | |||
281 | } | |||
282 | ||||
283 | bool | |||
284 | RegUseTracker::isRegUsedByUsesOtherThan(const SCEV *Reg, size_t LUIdx) const { | |||
285 | RegUsesTy::const_iterator I = RegUsesMap.find(Reg); | |||
286 | if (I == RegUsesMap.end()) | |||
287 | return false; | |||
288 | const SmallBitVector &UsedByIndices = I->second.UsedByIndices; | |||
289 | int i = UsedByIndices.find_first(); | |||
290 | if (i == -1) return false; | |||
291 | if ((size_t)i != LUIdx) return true; | |||
292 | return UsedByIndices.find_next(i) != -1; | |||
293 | } | |||
294 | ||||
295 | const SmallBitVector &RegUseTracker::getUsedByIndices(const SCEV *Reg) const { | |||
296 | RegUsesTy::const_iterator I = RegUsesMap.find(Reg); | |||
297 | assert(I != RegUsesMap.end() && "Unknown register!")(static_cast <bool> (I != RegUsesMap.end() && "Unknown register!" ) ? void (0) : __assert_fail ("I != RegUsesMap.end() && \"Unknown register!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 297, __extension__ __PRETTY_FUNCTION__)); | |||
298 | return I->second.UsedByIndices; | |||
299 | } | |||
300 | ||||
301 | void RegUseTracker::clear() { | |||
302 | RegUsesMap.clear(); | |||
303 | RegSequence.clear(); | |||
304 | } | |||
305 | ||||
306 | namespace { | |||
307 | ||||
308 | /// This class holds information that describes a formula for computing | |||
309 | /// satisfying a use. It may include broken-out immediates and scaled registers. | |||
310 | struct Formula { | |||
311 | /// Global base address used for complex addressing. | |||
312 | GlobalValue *BaseGV = nullptr; | |||
313 | ||||
314 | /// Base offset for complex addressing. | |||
315 | int64_t BaseOffset = 0; | |||
316 | ||||
317 | /// Whether any complex addressing has a base register. | |||
318 | bool HasBaseReg = false; | |||
319 | ||||
320 | /// The scale of any complex addressing. | |||
321 | int64_t Scale = 0; | |||
322 | ||||
323 | /// The list of "base" registers for this use. When this is non-empty. The | |||
324 | /// canonical representation of a formula is | |||
325 | /// 1. BaseRegs.size > 1 implies ScaledReg != NULL and | |||
326 | /// 2. ScaledReg != NULL implies Scale != 1 || !BaseRegs.empty(). | |||
327 | /// 3. The reg containing recurrent expr related with currect loop in the | |||
328 | /// formula should be put in the ScaledReg. | |||
329 | /// #1 enforces that the scaled register is always used when at least two | |||
330 | /// registers are needed by the formula: e.g., reg1 + reg2 is reg1 + 1 * reg2. | |||
331 | /// #2 enforces that 1 * reg is reg. | |||
332 | /// #3 ensures invariant regs with respect to current loop can be combined | |||
333 | /// together in LSR codegen. | |||
334 | /// This invariant can be temporarily broken while building a formula. | |||
335 | /// However, every formula inserted into the LSRInstance must be in canonical | |||
336 | /// form. | |||
337 | SmallVector<const SCEV *, 4> BaseRegs; | |||
338 | ||||
339 | /// The 'scaled' register for this use. This should be non-null when Scale is | |||
340 | /// not zero. | |||
341 | const SCEV *ScaledReg = nullptr; | |||
342 | ||||
343 | /// An additional constant offset which added near the use. This requires a | |||
344 | /// temporary register, but the offset itself can live in an add immediate | |||
345 | /// field rather than a register. | |||
346 | int64_t UnfoldedOffset = 0; | |||
347 | ||||
348 | Formula() = default; | |||
349 | ||||
350 | void initialMatch(const SCEV *S, Loop *L, ScalarEvolution &SE); | |||
351 | ||||
352 | bool isCanonical(const Loop &L) const; | |||
353 | ||||
354 | void canonicalize(const Loop &L); | |||
355 | ||||
356 | bool unscale(); | |||
357 | ||||
358 | bool hasZeroEnd() const; | |||
359 | ||||
360 | size_t getNumRegs() const; | |||
361 | Type *getType() const; | |||
362 | ||||
363 | void deleteBaseReg(const SCEV *&S); | |||
364 | ||||
365 | bool referencesReg(const SCEV *S) const; | |||
366 | bool hasRegsUsedByUsesOtherThan(size_t LUIdx, | |||
367 | const RegUseTracker &RegUses) const; | |||
368 | ||||
369 | void print(raw_ostream &OS) const; | |||
370 | void dump() const; | |||
371 | }; | |||
372 | ||||
373 | } // end anonymous namespace | |||
374 | ||||
375 | /// Recursion helper for initialMatch. | |||
376 | static void DoInitialMatch(const SCEV *S, Loop *L, | |||
377 | SmallVectorImpl<const SCEV *> &Good, | |||
378 | SmallVectorImpl<const SCEV *> &Bad, | |||
379 | ScalarEvolution &SE) { | |||
380 | // Collect expressions which properly dominate the loop header. | |||
381 | if (SE.properlyDominates(S, L->getHeader())) { | |||
382 | Good.push_back(S); | |||
383 | return; | |||
384 | } | |||
385 | ||||
386 | // Look at add operands. | |||
387 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) { | |||
388 | for (const SCEV *S : Add->operands()) | |||
389 | DoInitialMatch(S, L, Good, Bad, SE); | |||
390 | return; | |||
391 | } | |||
392 | ||||
393 | // Look at addrec operands. | |||
394 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) | |||
395 | if (!AR->getStart()->isZero() && AR->isAffine()) { | |||
396 | DoInitialMatch(AR->getStart(), L, Good, Bad, SE); | |||
397 | DoInitialMatch(SE.getAddRecExpr(SE.getConstant(AR->getType(), 0), | |||
398 | AR->getStepRecurrence(SE), | |||
399 | // FIXME: AR->getNoWrapFlags() | |||
400 | AR->getLoop(), SCEV::FlagAnyWrap), | |||
401 | L, Good, Bad, SE); | |||
402 | return; | |||
403 | } | |||
404 | ||||
405 | // Handle a multiplication by -1 (negation) if it didn't fold. | |||
406 | if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) | |||
407 | if (Mul->getOperand(0)->isAllOnesValue()) { | |||
408 | SmallVector<const SCEV *, 4> Ops(Mul->op_begin()+1, Mul->op_end()); | |||
409 | const SCEV *NewMul = SE.getMulExpr(Ops); | |||
410 | ||||
411 | SmallVector<const SCEV *, 4> MyGood; | |||
412 | SmallVector<const SCEV *, 4> MyBad; | |||
413 | DoInitialMatch(NewMul, L, MyGood, MyBad, SE); | |||
414 | const SCEV *NegOne = SE.getSCEV(ConstantInt::getAllOnesValue( | |||
415 | SE.getEffectiveSCEVType(NewMul->getType()))); | |||
416 | for (const SCEV *S : MyGood) | |||
417 | Good.push_back(SE.getMulExpr(NegOne, S)); | |||
418 | for (const SCEV *S : MyBad) | |||
419 | Bad.push_back(SE.getMulExpr(NegOne, S)); | |||
420 | return; | |||
421 | } | |||
422 | ||||
423 | // Ok, we can't do anything interesting. Just stuff the whole thing into a | |||
424 | // register and hope for the best. | |||
425 | Bad.push_back(S); | |||
426 | } | |||
427 | ||||
428 | /// Incorporate loop-variant parts of S into this Formula, attempting to keep | |||
429 | /// all loop-invariant and loop-computable values in a single base register. | |||
430 | void Formula::initialMatch(const SCEV *S, Loop *L, ScalarEvolution &SE) { | |||
431 | SmallVector<const SCEV *, 4> Good; | |||
432 | SmallVector<const SCEV *, 4> Bad; | |||
433 | DoInitialMatch(S, L, Good, Bad, SE); | |||
434 | if (!Good.empty()) { | |||
435 | const SCEV *Sum = SE.getAddExpr(Good); | |||
436 | if (!Sum->isZero()) | |||
437 | BaseRegs.push_back(Sum); | |||
438 | HasBaseReg = true; | |||
439 | } | |||
440 | if (!Bad.empty()) { | |||
441 | const SCEV *Sum = SE.getAddExpr(Bad); | |||
442 | if (!Sum->isZero()) | |||
443 | BaseRegs.push_back(Sum); | |||
444 | HasBaseReg = true; | |||
445 | } | |||
446 | canonicalize(*L); | |||
447 | } | |||
448 | ||||
449 | /// Check whether or not this formula satisfies the canonical | |||
450 | /// representation. | |||
451 | /// \see Formula::BaseRegs. | |||
452 | bool Formula::isCanonical(const Loop &L) const { | |||
453 | if (!ScaledReg) | |||
454 | return BaseRegs.size() <= 1; | |||
455 | ||||
456 | if (Scale != 1) | |||
457 | return true; | |||
458 | ||||
459 | if (Scale == 1 && BaseRegs.empty()) | |||
460 | return false; | |||
461 | ||||
462 | const SCEVAddRecExpr *SAR = dyn_cast<const SCEVAddRecExpr>(ScaledReg); | |||
463 | if (SAR && SAR->getLoop() == &L) | |||
464 | return true; | |||
465 | ||||
466 | // If ScaledReg is not a recurrent expr, or it is but its loop is not current | |||
467 | // loop, meanwhile BaseRegs contains a recurrent expr reg related with current | |||
468 | // loop, we want to swap the reg in BaseRegs with ScaledReg. | |||
469 | auto I = | |||
470 | find_if(make_range(BaseRegs.begin(), BaseRegs.end()), [&](const SCEV *S) { | |||
471 | return isa<const SCEVAddRecExpr>(S) && | |||
472 | (cast<SCEVAddRecExpr>(S)->getLoop() == &L); | |||
473 | }); | |||
474 | return I == BaseRegs.end(); | |||
475 | } | |||
476 | ||||
477 | /// Helper method to morph a formula into its canonical representation. | |||
478 | /// \see Formula::BaseRegs. | |||
479 | /// Every formula having more than one base register, must use the ScaledReg | |||
480 | /// field. Otherwise, we would have to do special cases everywhere in LSR | |||
481 | /// to treat reg1 + reg2 + ... the same way as reg1 + 1*reg2 + ... | |||
482 | /// On the other hand, 1*reg should be canonicalized into reg. | |||
483 | void Formula::canonicalize(const Loop &L) { | |||
484 | if (isCanonical(L)) | |||
485 | return; | |||
486 | // So far we did not need this case. This is easy to implement but it is | |||
487 | // useless to maintain dead code. Beside it could hurt compile time. | |||
488 | assert(!BaseRegs.empty() && "1*reg => reg, should not be needed.")(static_cast <bool> (!BaseRegs.empty() && "1*reg => reg, should not be needed." ) ? void (0) : __assert_fail ("!BaseRegs.empty() && \"1*reg => reg, should not be needed.\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 488, __extension__ __PRETTY_FUNCTION__)); | |||
489 | ||||
490 | // Keep the invariant sum in BaseRegs and one of the variant sum in ScaledReg. | |||
491 | if (!ScaledReg) { | |||
492 | ScaledReg = BaseRegs.back(); | |||
493 | BaseRegs.pop_back(); | |||
494 | Scale = 1; | |||
495 | } | |||
496 | ||||
497 | // If ScaledReg is an invariant with respect to L, find the reg from | |||
498 | // BaseRegs containing the recurrent expr related with Loop L. Swap the | |||
499 | // reg with ScaledReg. | |||
500 | const SCEVAddRecExpr *SAR = dyn_cast<const SCEVAddRecExpr>(ScaledReg); | |||
501 | if (!SAR || SAR->getLoop() != &L) { | |||
502 | auto I = find_if(make_range(BaseRegs.begin(), BaseRegs.end()), | |||
503 | [&](const SCEV *S) { | |||
504 | return isa<const SCEVAddRecExpr>(S) && | |||
505 | (cast<SCEVAddRecExpr>(S)->getLoop() == &L); | |||
506 | }); | |||
507 | if (I != BaseRegs.end()) | |||
508 | std::swap(ScaledReg, *I); | |||
509 | } | |||
510 | } | |||
511 | ||||
512 | /// Get rid of the scale in the formula. | |||
513 | /// In other words, this method morphes reg1 + 1*reg2 into reg1 + reg2. | |||
514 | /// \return true if it was possible to get rid of the scale, false otherwise. | |||
515 | /// \note After this operation the formula may not be in the canonical form. | |||
516 | bool Formula::unscale() { | |||
517 | if (Scale != 1) | |||
518 | return false; | |||
519 | Scale = 0; | |||
520 | BaseRegs.push_back(ScaledReg); | |||
521 | ScaledReg = nullptr; | |||
522 | return true; | |||
523 | } | |||
524 | ||||
525 | bool Formula::hasZeroEnd() const { | |||
526 | if (UnfoldedOffset || BaseOffset) | |||
527 | return false; | |||
528 | if (BaseRegs.size() != 1 || ScaledReg) | |||
529 | return false; | |||
530 | return true; | |||
531 | } | |||
532 | ||||
533 | /// Return the total number of register operands used by this formula. This does | |||
534 | /// not include register uses implied by non-constant addrec strides. | |||
535 | size_t Formula::getNumRegs() const { | |||
536 | return !!ScaledReg + BaseRegs.size(); | |||
537 | } | |||
538 | ||||
539 | /// Return the type of this formula, if it has one, or null otherwise. This type | |||
540 | /// is meaningless except for the bit size. | |||
541 | Type *Formula::getType() const { | |||
542 | return !BaseRegs.empty() ? BaseRegs.front()->getType() : | |||
543 | ScaledReg ? ScaledReg->getType() : | |||
544 | BaseGV ? BaseGV->getType() : | |||
545 | nullptr; | |||
546 | } | |||
547 | ||||
548 | /// Delete the given base reg from the BaseRegs list. | |||
549 | void Formula::deleteBaseReg(const SCEV *&S) { | |||
550 | if (&S != &BaseRegs.back()) | |||
551 | std::swap(S, BaseRegs.back()); | |||
552 | BaseRegs.pop_back(); | |||
553 | } | |||
554 | ||||
555 | /// Test if this formula references the given register. | |||
556 | bool Formula::referencesReg(const SCEV *S) const { | |||
557 | return S == ScaledReg || is_contained(BaseRegs, S); | |||
558 | } | |||
559 | ||||
560 | /// Test whether this formula uses registers which are used by uses other than | |||
561 | /// the use with the given index. | |||
562 | bool Formula::hasRegsUsedByUsesOtherThan(size_t LUIdx, | |||
563 | const RegUseTracker &RegUses) const { | |||
564 | if (ScaledReg) | |||
565 | if (RegUses.isRegUsedByUsesOtherThan(ScaledReg, LUIdx)) | |||
566 | return true; | |||
567 | for (const SCEV *BaseReg : BaseRegs) | |||
568 | if (RegUses.isRegUsedByUsesOtherThan(BaseReg, LUIdx)) | |||
569 | return true; | |||
570 | return false; | |||
571 | } | |||
572 | ||||
573 | #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) | |||
574 | void Formula::print(raw_ostream &OS) const { | |||
575 | bool First = true; | |||
576 | if (BaseGV) { | |||
577 | if (!First) OS << " + "; else First = false; | |||
578 | BaseGV->printAsOperand(OS, /*PrintType=*/false); | |||
579 | } | |||
580 | if (BaseOffset != 0) { | |||
581 | if (!First) OS << " + "; else First = false; | |||
582 | OS << BaseOffset; | |||
583 | } | |||
584 | for (const SCEV *BaseReg : BaseRegs) { | |||
585 | if (!First) OS << " + "; else First = false; | |||
586 | OS << "reg(" << *BaseReg << ')'; | |||
587 | } | |||
588 | if (HasBaseReg && BaseRegs.empty()) { | |||
589 | if (!First) OS << " + "; else First = false; | |||
590 | OS << "**error: HasBaseReg**"; | |||
591 | } else if (!HasBaseReg && !BaseRegs.empty()) { | |||
592 | if (!First) OS << " + "; else First = false; | |||
593 | OS << "**error: !HasBaseReg**"; | |||
594 | } | |||
595 | if (Scale != 0) { | |||
596 | if (!First) OS << " + "; else First = false; | |||
597 | OS << Scale << "*reg("; | |||
598 | if (ScaledReg) | |||
599 | OS << *ScaledReg; | |||
600 | else | |||
601 | OS << "<unknown>"; | |||
602 | OS << ')'; | |||
603 | } | |||
604 | if (UnfoldedOffset != 0) { | |||
605 | if (!First) OS << " + "; | |||
606 | OS << "imm(" << UnfoldedOffset << ')'; | |||
607 | } | |||
608 | } | |||
609 | ||||
610 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void Formula::dump() const { | |||
611 | print(errs()); errs() << '\n'; | |||
612 | } | |||
613 | #endif | |||
614 | ||||
615 | /// Return true if the given addrec can be sign-extended without changing its | |||
616 | /// value. | |||
617 | static bool isAddRecSExtable(const SCEVAddRecExpr *AR, ScalarEvolution &SE) { | |||
618 | Type *WideTy = | |||
619 | IntegerType::get(SE.getContext(), SE.getTypeSizeInBits(AR->getType()) + 1); | |||
620 | return isa<SCEVAddRecExpr>(SE.getSignExtendExpr(AR, WideTy)); | |||
621 | } | |||
622 | ||||
623 | /// Return true if the given add can be sign-extended without changing its | |||
624 | /// value. | |||
625 | static bool isAddSExtable(const SCEVAddExpr *A, ScalarEvolution &SE) { | |||
626 | Type *WideTy = | |||
627 | IntegerType::get(SE.getContext(), SE.getTypeSizeInBits(A->getType()) + 1); | |||
628 | return isa<SCEVAddExpr>(SE.getSignExtendExpr(A, WideTy)); | |||
629 | } | |||
630 | ||||
631 | /// Return true if the given mul can be sign-extended without changing its | |||
632 | /// value. | |||
633 | static bool isMulSExtable(const SCEVMulExpr *M, ScalarEvolution &SE) { | |||
634 | Type *WideTy = | |||
635 | IntegerType::get(SE.getContext(), | |||
636 | SE.getTypeSizeInBits(M->getType()) * M->getNumOperands()); | |||
637 | return isa<SCEVMulExpr>(SE.getSignExtendExpr(M, WideTy)); | |||
638 | } | |||
639 | ||||
640 | /// Return an expression for LHS /s RHS, if it can be determined and if the | |||
641 | /// remainder is known to be zero, or null otherwise. If IgnoreSignificantBits | |||
642 | /// is true, expressions like (X * Y) /s Y are simplified to Y, ignoring that | |||
643 | /// the multiplication may overflow, which is useful when the result will be | |||
644 | /// used in a context where the most significant bits are ignored. | |||
645 | static const SCEV *getExactSDiv(const SCEV *LHS, const SCEV *RHS, | |||
646 | ScalarEvolution &SE, | |||
647 | bool IgnoreSignificantBits = false) { | |||
648 | // Handle the trivial case, which works for any SCEV type. | |||
649 | if (LHS == RHS) | |||
650 | return SE.getConstant(LHS->getType(), 1); | |||
651 | ||||
652 | // Handle a few RHS special cases. | |||
653 | const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS); | |||
654 | if (RC) { | |||
655 | const APInt &RA = RC->getAPInt(); | |||
656 | // Handle x /s -1 as x * -1, to give ScalarEvolution a chance to do | |||
657 | // some folding. | |||
658 | if (RA.isAllOnesValue()) | |||
659 | return SE.getMulExpr(LHS, RC); | |||
660 | // Handle x /s 1 as x. | |||
661 | if (RA == 1) | |||
662 | return LHS; | |||
663 | } | |||
664 | ||||
665 | // Check for a division of a constant by a constant. | |||
666 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(LHS)) { | |||
667 | if (!RC) | |||
668 | return nullptr; | |||
669 | const APInt &LA = C->getAPInt(); | |||
670 | const APInt &RA = RC->getAPInt(); | |||
671 | if (LA.srem(RA) != 0) | |||
672 | return nullptr; | |||
673 | return SE.getConstant(LA.sdiv(RA)); | |||
674 | } | |||
675 | ||||
676 | // Distribute the sdiv over addrec operands, if the addrec doesn't overflow. | |||
677 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS)) { | |||
678 | if ((IgnoreSignificantBits || isAddRecSExtable(AR, SE)) && AR->isAffine()) { | |||
679 | const SCEV *Step = getExactSDiv(AR->getStepRecurrence(SE), RHS, SE, | |||
680 | IgnoreSignificantBits); | |||
681 | if (!Step) return nullptr; | |||
682 | const SCEV *Start = getExactSDiv(AR->getStart(), RHS, SE, | |||
683 | IgnoreSignificantBits); | |||
684 | if (!Start) return nullptr; | |||
685 | // FlagNW is independent of the start value, step direction, and is | |||
686 | // preserved with smaller magnitude steps. | |||
687 | // FIXME: AR->getNoWrapFlags(SCEV::FlagNW) | |||
688 | return SE.getAddRecExpr(Start, Step, AR->getLoop(), SCEV::FlagAnyWrap); | |||
689 | } | |||
690 | return nullptr; | |||
691 | } | |||
692 | ||||
693 | // Distribute the sdiv over add operands, if the add doesn't overflow. | |||
694 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(LHS)) { | |||
695 | if (IgnoreSignificantBits || isAddSExtable(Add, SE)) { | |||
696 | SmallVector<const SCEV *, 8> Ops; | |||
697 | for (const SCEV *S : Add->operands()) { | |||
698 | const SCEV *Op = getExactSDiv(S, RHS, SE, IgnoreSignificantBits); | |||
699 | if (!Op) return nullptr; | |||
700 | Ops.push_back(Op); | |||
701 | } | |||
702 | return SE.getAddExpr(Ops); | |||
703 | } | |||
704 | return nullptr; | |||
705 | } | |||
706 | ||||
707 | // Check for a multiply operand that we can pull RHS out of. | |||
708 | if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS)) { | |||
709 | if (IgnoreSignificantBits || isMulSExtable(Mul, SE)) { | |||
710 | SmallVector<const SCEV *, 4> Ops; | |||
711 | bool Found = false; | |||
712 | for (const SCEV *S : Mul->operands()) { | |||
713 | if (!Found) | |||
714 | if (const SCEV *Q = getExactSDiv(S, RHS, SE, | |||
715 | IgnoreSignificantBits)) { | |||
716 | S = Q; | |||
717 | Found = true; | |||
718 | } | |||
719 | Ops.push_back(S); | |||
720 | } | |||
721 | return Found ? SE.getMulExpr(Ops) : nullptr; | |||
722 | } | |||
723 | return nullptr; | |||
724 | } | |||
725 | ||||
726 | // Otherwise we don't know. | |||
727 | return nullptr; | |||
728 | } | |||
729 | ||||
730 | /// If S involves the addition of a constant integer value, return that integer | |||
731 | /// value, and mutate S to point to a new SCEV with that value excluded. | |||
732 | static int64_t ExtractImmediate(const SCEV *&S, ScalarEvolution &SE) { | |||
733 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) { | |||
734 | if (C->getAPInt().getMinSignedBits() <= 64) { | |||
735 | S = SE.getConstant(C->getType(), 0); | |||
736 | return C->getValue()->getSExtValue(); | |||
737 | } | |||
738 | } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) { | |||
739 | SmallVector<const SCEV *, 8> NewOps(Add->op_begin(), Add->op_end()); | |||
740 | int64_t Result = ExtractImmediate(NewOps.front(), SE); | |||
741 | if (Result != 0) | |||
742 | S = SE.getAddExpr(NewOps); | |||
743 | return Result; | |||
744 | } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) { | |||
745 | SmallVector<const SCEV *, 8> NewOps(AR->op_begin(), AR->op_end()); | |||
746 | int64_t Result = ExtractImmediate(NewOps.front(), SE); | |||
747 | if (Result != 0) | |||
748 | S = SE.getAddRecExpr(NewOps, AR->getLoop(), | |||
749 | // FIXME: AR->getNoWrapFlags(SCEV::FlagNW) | |||
750 | SCEV::FlagAnyWrap); | |||
751 | return Result; | |||
752 | } | |||
753 | return 0; | |||
754 | } | |||
755 | ||||
756 | /// If S involves the addition of a GlobalValue address, return that symbol, and | |||
757 | /// mutate S to point to a new SCEV with that value excluded. | |||
758 | static GlobalValue *ExtractSymbol(const SCEV *&S, ScalarEvolution &SE) { | |||
759 | if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) { | |||
760 | if (GlobalValue *GV = dyn_cast<GlobalValue>(U->getValue())) { | |||
761 | S = SE.getConstant(GV->getType(), 0); | |||
762 | return GV; | |||
763 | } | |||
764 | } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) { | |||
765 | SmallVector<const SCEV *, 8> NewOps(Add->op_begin(), Add->op_end()); | |||
766 | GlobalValue *Result = ExtractSymbol(NewOps.back(), SE); | |||
767 | if (Result) | |||
768 | S = SE.getAddExpr(NewOps); | |||
769 | return Result; | |||
770 | } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) { | |||
771 | SmallVector<const SCEV *, 8> NewOps(AR->op_begin(), AR->op_end()); | |||
772 | GlobalValue *Result = ExtractSymbol(NewOps.front(), SE); | |||
773 | if (Result) | |||
774 | S = SE.getAddRecExpr(NewOps, AR->getLoop(), | |||
775 | // FIXME: AR->getNoWrapFlags(SCEV::FlagNW) | |||
776 | SCEV::FlagAnyWrap); | |||
777 | return Result; | |||
778 | } | |||
779 | return nullptr; | |||
780 | } | |||
781 | ||||
782 | /// Returns true if the specified instruction is using the specified value as an | |||
783 | /// address. | |||
784 | static bool isAddressUse(const TargetTransformInfo &TTI, | |||
785 | Instruction *Inst, Value *OperandVal) { | |||
786 | bool isAddress = isa<LoadInst>(Inst); | |||
787 | if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) { | |||
788 | if (SI->getPointerOperand() == OperandVal) | |||
789 | isAddress = true; | |||
790 | } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) { | |||
791 | // Addressing modes can also be folded into prefetches and a variety | |||
792 | // of intrinsics. | |||
793 | switch (II->getIntrinsicID()) { | |||
794 | case Intrinsic::memset: | |||
795 | case Intrinsic::prefetch: | |||
796 | if (II->getArgOperand(0) == OperandVal) | |||
797 | isAddress = true; | |||
798 | break; | |||
799 | case Intrinsic::memmove: | |||
800 | case Intrinsic::memcpy: | |||
801 | if (II->getArgOperand(0) == OperandVal || | |||
802 | II->getArgOperand(1) == OperandVal) | |||
803 | isAddress = true; | |||
804 | break; | |||
805 | default: { | |||
806 | MemIntrinsicInfo IntrInfo; | |||
807 | if (TTI.getTgtMemIntrinsic(II, IntrInfo)) { | |||
808 | if (IntrInfo.PtrVal == OperandVal) | |||
809 | isAddress = true; | |||
810 | } | |||
811 | } | |||
812 | } | |||
813 | } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(Inst)) { | |||
814 | if (RMW->getPointerOperand() == OperandVal) | |||
815 | isAddress = true; | |||
816 | } else if (AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(Inst)) { | |||
817 | if (CmpX->getPointerOperand() == OperandVal) | |||
818 | isAddress = true; | |||
819 | } | |||
820 | return isAddress; | |||
821 | } | |||
822 | ||||
823 | /// Return the type of the memory being accessed. | |||
824 | static MemAccessTy getAccessType(const TargetTransformInfo &TTI, | |||
825 | Instruction *Inst, Value *OperandVal) { | |||
826 | MemAccessTy AccessTy(Inst->getType(), MemAccessTy::UnknownAddressSpace); | |||
827 | if (const StoreInst *SI = dyn_cast<StoreInst>(Inst)) { | |||
828 | AccessTy.MemTy = SI->getOperand(0)->getType(); | |||
829 | AccessTy.AddrSpace = SI->getPointerAddressSpace(); | |||
830 | } else if (const LoadInst *LI = dyn_cast<LoadInst>(Inst)) { | |||
831 | AccessTy.AddrSpace = LI->getPointerAddressSpace(); | |||
832 | } else if (const AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(Inst)) { | |||
833 | AccessTy.AddrSpace = RMW->getPointerAddressSpace(); | |||
834 | } else if (const AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(Inst)) { | |||
835 | AccessTy.AddrSpace = CmpX->getPointerAddressSpace(); | |||
836 | } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) { | |||
837 | switch (II->getIntrinsicID()) { | |||
838 | case Intrinsic::prefetch: | |||
839 | case Intrinsic::memset: | |||
840 | AccessTy.AddrSpace = II->getArgOperand(0)->getType()->getPointerAddressSpace(); | |||
841 | AccessTy.MemTy = OperandVal->getType(); | |||
842 | break; | |||
843 | case Intrinsic::memmove: | |||
844 | case Intrinsic::memcpy: | |||
845 | AccessTy.AddrSpace = OperandVal->getType()->getPointerAddressSpace(); | |||
846 | AccessTy.MemTy = OperandVal->getType(); | |||
847 | break; | |||
848 | default: { | |||
849 | MemIntrinsicInfo IntrInfo; | |||
850 | if (TTI.getTgtMemIntrinsic(II, IntrInfo) && IntrInfo.PtrVal) { | |||
851 | AccessTy.AddrSpace | |||
852 | = IntrInfo.PtrVal->getType()->getPointerAddressSpace(); | |||
853 | } | |||
854 | ||||
855 | break; | |||
856 | } | |||
857 | } | |||
858 | } | |||
859 | ||||
860 | // All pointers have the same requirements, so canonicalize them to an | |||
861 | // arbitrary pointer type to minimize variation. | |||
862 | if (PointerType *PTy = dyn_cast<PointerType>(AccessTy.MemTy)) | |||
863 | AccessTy.MemTy = PointerType::get(IntegerType::get(PTy->getContext(), 1), | |||
864 | PTy->getAddressSpace()); | |||
865 | ||||
866 | return AccessTy; | |||
867 | } | |||
868 | ||||
869 | /// Return true if this AddRec is already a phi in its loop. | |||
870 | static bool isExistingPhi(const SCEVAddRecExpr *AR, ScalarEvolution &SE) { | |||
871 | for (PHINode &PN : AR->getLoop()->getHeader()->phis()) { | |||
872 | if (SE.isSCEVable(PN.getType()) && | |||
873 | (SE.getEffectiveSCEVType(PN.getType()) == | |||
874 | SE.getEffectiveSCEVType(AR->getType())) && | |||
875 | SE.getSCEV(&PN) == AR) | |||
876 | return true; | |||
877 | } | |||
878 | return false; | |||
879 | } | |||
880 | ||||
881 | /// Check if expanding this expression is likely to incur significant cost. This | |||
882 | /// is tricky because SCEV doesn't track which expressions are actually computed | |||
883 | /// by the current IR. | |||
884 | /// | |||
885 | /// We currently allow expansion of IV increments that involve adds, | |||
886 | /// multiplication by constants, and AddRecs from existing phis. | |||
887 | /// | |||
888 | /// TODO: Allow UDivExpr if we can find an existing IV increment that is an | |||
889 | /// obvious multiple of the UDivExpr. | |||
890 | static bool isHighCostExpansion(const SCEV *S, | |||
891 | SmallPtrSetImpl<const SCEV*> &Processed, | |||
892 | ScalarEvolution &SE) { | |||
893 | // Zero/One operand expressions | |||
894 | switch (S->getSCEVType()) { | |||
895 | case scUnknown: | |||
896 | case scConstant: | |||
897 | return false; | |||
898 | case scTruncate: | |||
899 | return isHighCostExpansion(cast<SCEVTruncateExpr>(S)->getOperand(), | |||
900 | Processed, SE); | |||
901 | case scZeroExtend: | |||
902 | return isHighCostExpansion(cast<SCEVZeroExtendExpr>(S)->getOperand(), | |||
903 | Processed, SE); | |||
904 | case scSignExtend: | |||
905 | return isHighCostExpansion(cast<SCEVSignExtendExpr>(S)->getOperand(), | |||
906 | Processed, SE); | |||
907 | } | |||
908 | ||||
909 | if (!Processed.insert(S).second) | |||
910 | return false; | |||
911 | ||||
912 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) { | |||
913 | for (const SCEV *S : Add->operands()) { | |||
914 | if (isHighCostExpansion(S, Processed, SE)) | |||
915 | return true; | |||
916 | } | |||
917 | return false; | |||
918 | } | |||
919 | ||||
920 | if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) { | |||
921 | if (Mul->getNumOperands() == 2) { | |||
922 | // Multiplication by a constant is ok | |||
923 | if (isa<SCEVConstant>(Mul->getOperand(0))) | |||
924 | return isHighCostExpansion(Mul->getOperand(1), Processed, SE); | |||
925 | ||||
926 | // If we have the value of one operand, check if an existing | |||
927 | // multiplication already generates this expression. | |||
928 | if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Mul->getOperand(1))) { | |||
929 | Value *UVal = U->getValue(); | |||
930 | for (User *UR : UVal->users()) { | |||
931 | // If U is a constant, it may be used by a ConstantExpr. | |||
932 | Instruction *UI = dyn_cast<Instruction>(UR); | |||
933 | if (UI && UI->getOpcode() == Instruction::Mul && | |||
934 | SE.isSCEVable(UI->getType())) { | |||
935 | return SE.getSCEV(UI) == Mul; | |||
936 | } | |||
937 | } | |||
938 | } | |||
939 | } | |||
940 | } | |||
941 | ||||
942 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) { | |||
943 | if (isExistingPhi(AR, SE)) | |||
944 | return false; | |||
945 | } | |||
946 | ||||
947 | // Fow now, consider any other type of expression (div/mul/min/max) high cost. | |||
948 | return true; | |||
949 | } | |||
950 | ||||
951 | /// If any of the instructions in the specified set are trivially dead, delete | |||
952 | /// them and see if this makes any of their operands subsequently dead. | |||
953 | static bool | |||
954 | DeleteTriviallyDeadInstructions(SmallVectorImpl<WeakTrackingVH> &DeadInsts) { | |||
955 | bool Changed = false; | |||
956 | ||||
957 | while (!DeadInsts.empty()) { | |||
958 | Value *V = DeadInsts.pop_back_val(); | |||
959 | Instruction *I = dyn_cast_or_null<Instruction>(V); | |||
960 | ||||
961 | if (!I || !isInstructionTriviallyDead(I)) | |||
962 | continue; | |||
963 | ||||
964 | for (Use &O : I->operands()) | |||
965 | if (Instruction *U = dyn_cast<Instruction>(O)) { | |||
966 | O = nullptr; | |||
967 | if (U->use_empty()) | |||
968 | DeadInsts.emplace_back(U); | |||
969 | } | |||
970 | ||||
971 | I->eraseFromParent(); | |||
972 | Changed = true; | |||
973 | } | |||
974 | ||||
975 | return Changed; | |||
976 | } | |||
977 | ||||
978 | namespace { | |||
979 | ||||
980 | class LSRUse; | |||
981 | ||||
982 | } // end anonymous namespace | |||
983 | ||||
984 | /// Check if the addressing mode defined by \p F is completely | |||
985 | /// folded in \p LU at isel time. | |||
986 | /// This includes address-mode folding and special icmp tricks. | |||
987 | /// This function returns true if \p LU can accommodate what \p F | |||
988 | /// defines and up to 1 base + 1 scaled + offset. | |||
989 | /// In other words, if \p F has several base registers, this function may | |||
990 | /// still return true. Therefore, users still need to account for | |||
991 | /// additional base registers and/or unfolded offsets to derive an | |||
992 | /// accurate cost model. | |||
993 | static bool isAMCompletelyFolded(const TargetTransformInfo &TTI, | |||
994 | const LSRUse &LU, const Formula &F); | |||
995 | ||||
996 | // Get the cost of the scaling factor used in F for LU. | |||
997 | static unsigned getScalingFactorCost(const TargetTransformInfo &TTI, | |||
998 | const LSRUse &LU, const Formula &F, | |||
999 | const Loop &L); | |||
1000 | ||||
1001 | namespace { | |||
1002 | ||||
1003 | /// This class is used to measure and compare candidate formulae. | |||
1004 | class Cost { | |||
1005 | TargetTransformInfo::LSRCost C; | |||
1006 | ||||
1007 | public: | |||
1008 | Cost() { | |||
1009 | C.Insns = 0; | |||
1010 | C.NumRegs = 0; | |||
1011 | C.AddRecCost = 0; | |||
1012 | C.NumIVMuls = 0; | |||
1013 | C.NumBaseAdds = 0; | |||
1014 | C.ImmCost = 0; | |||
1015 | C.SetupCost = 0; | |||
1016 | C.ScaleCost = 0; | |||
1017 | } | |||
1018 | ||||
1019 | bool isLess(Cost &Other, const TargetTransformInfo &TTI); | |||
1020 | ||||
1021 | void Lose(); | |||
1022 | ||||
1023 | #ifndef NDEBUG | |||
1024 | // Once any of the metrics loses, they must all remain losers. | |||
1025 | bool isValid() { | |||
1026 | return ((C.Insns | C.NumRegs | C.AddRecCost | C.NumIVMuls | C.NumBaseAdds | |||
1027 | | C.ImmCost | C.SetupCost | C.ScaleCost) != ~0u) | |||
1028 | || ((C.Insns & C.NumRegs & C.AddRecCost & C.NumIVMuls & C.NumBaseAdds | |||
1029 | & C.ImmCost & C.SetupCost & C.ScaleCost) == ~0u); | |||
1030 | } | |||
1031 | #endif | |||
1032 | ||||
1033 | bool isLoser() { | |||
1034 | assert(isValid() && "invalid cost")(static_cast <bool> (isValid() && "invalid cost" ) ? void (0) : __assert_fail ("isValid() && \"invalid cost\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1034, __extension__ __PRETTY_FUNCTION__)); | |||
1035 | return C.NumRegs == ~0u; | |||
1036 | } | |||
1037 | ||||
1038 | void RateFormula(const TargetTransformInfo &TTI, | |||
1039 | const Formula &F, | |||
1040 | SmallPtrSetImpl<const SCEV *> &Regs, | |||
1041 | const DenseSet<const SCEV *> &VisitedRegs, | |||
1042 | const Loop *L, | |||
1043 | ScalarEvolution &SE, DominatorTree &DT, | |||
1044 | const LSRUse &LU, | |||
1045 | SmallPtrSetImpl<const SCEV *> *LoserRegs = nullptr); | |||
1046 | ||||
1047 | void print(raw_ostream &OS) const; | |||
1048 | void dump() const; | |||
1049 | ||||
1050 | private: | |||
1051 | void RateRegister(const SCEV *Reg, | |||
1052 | SmallPtrSetImpl<const SCEV *> &Regs, | |||
1053 | const Loop *L, | |||
1054 | ScalarEvolution &SE, DominatorTree &DT, | |||
1055 | const TargetTransformInfo &TTI); | |||
1056 | void RatePrimaryRegister(const SCEV *Reg, | |||
1057 | SmallPtrSetImpl<const SCEV *> &Regs, | |||
1058 | const Loop *L, | |||
1059 | ScalarEvolution &SE, DominatorTree &DT, | |||
1060 | SmallPtrSetImpl<const SCEV *> *LoserRegs, | |||
1061 | const TargetTransformInfo &TTI); | |||
1062 | }; | |||
1063 | ||||
1064 | /// An operand value in an instruction which is to be replaced with some | |||
1065 | /// equivalent, possibly strength-reduced, replacement. | |||
1066 | struct LSRFixup { | |||
1067 | /// The instruction which will be updated. | |||
1068 | Instruction *UserInst = nullptr; | |||
1069 | ||||
1070 | /// The operand of the instruction which will be replaced. The operand may be | |||
1071 | /// used more than once; every instance will be replaced. | |||
1072 | Value *OperandValToReplace = nullptr; | |||
1073 | ||||
1074 | /// If this user is to use the post-incremented value of an induction | |||
1075 | /// variable, this set is non-empty and holds the loops associated with the | |||
1076 | /// induction variable. | |||
1077 | PostIncLoopSet PostIncLoops; | |||
1078 | ||||
1079 | /// A constant offset to be added to the LSRUse expression. This allows | |||
1080 | /// multiple fixups to share the same LSRUse with different offsets, for | |||
1081 | /// example in an unrolled loop. | |||
1082 | int64_t Offset = 0; | |||
1083 | ||||
1084 | LSRFixup() = default; | |||
1085 | ||||
1086 | bool isUseFullyOutsideLoop(const Loop *L) const; | |||
1087 | ||||
1088 | void print(raw_ostream &OS) const; | |||
1089 | void dump() const; | |||
1090 | }; | |||
1091 | ||||
1092 | /// A DenseMapInfo implementation for holding DenseMaps and DenseSets of sorted | |||
1093 | /// SmallVectors of const SCEV*. | |||
1094 | struct UniquifierDenseMapInfo { | |||
1095 | static SmallVector<const SCEV *, 4> getEmptyKey() { | |||
1096 | SmallVector<const SCEV *, 4> V; | |||
1097 | V.push_back(reinterpret_cast<const SCEV *>(-1)); | |||
1098 | return V; | |||
1099 | } | |||
1100 | ||||
1101 | static SmallVector<const SCEV *, 4> getTombstoneKey() { | |||
1102 | SmallVector<const SCEV *, 4> V; | |||
1103 | V.push_back(reinterpret_cast<const SCEV *>(-2)); | |||
1104 | return V; | |||
1105 | } | |||
1106 | ||||
1107 | static unsigned getHashValue(const SmallVector<const SCEV *, 4> &V) { | |||
1108 | return static_cast<unsigned>(hash_combine_range(V.begin(), V.end())); | |||
1109 | } | |||
1110 | ||||
1111 | static bool isEqual(const SmallVector<const SCEV *, 4> &LHS, | |||
1112 | const SmallVector<const SCEV *, 4> &RHS) { | |||
1113 | return LHS == RHS; | |||
1114 | } | |||
1115 | }; | |||
1116 | ||||
1117 | /// This class holds the state that LSR keeps for each use in IVUsers, as well | |||
1118 | /// as uses invented by LSR itself. It includes information about what kinds of | |||
1119 | /// things can be folded into the user, information about the user itself, and | |||
1120 | /// information about how the use may be satisfied. TODO: Represent multiple | |||
1121 | /// users of the same expression in common? | |||
1122 | class LSRUse { | |||
1123 | DenseSet<SmallVector<const SCEV *, 4>, UniquifierDenseMapInfo> Uniquifier; | |||
1124 | ||||
1125 | public: | |||
1126 | /// An enum for a kind of use, indicating what types of scaled and immediate | |||
1127 | /// operands it might support. | |||
1128 | enum KindType { | |||
1129 | Basic, ///< A normal use, with no folding. | |||
1130 | Special, ///< A special case of basic, allowing -1 scales. | |||
1131 | Address, ///< An address use; folding according to TargetLowering | |||
1132 | ICmpZero ///< An equality icmp with both operands folded into one. | |||
1133 | // TODO: Add a generic icmp too? | |||
1134 | }; | |||
1135 | ||||
1136 | using SCEVUseKindPair = PointerIntPair<const SCEV *, 2, KindType>; | |||
1137 | ||||
1138 | KindType Kind; | |||
1139 | MemAccessTy AccessTy; | |||
1140 | ||||
1141 | /// The list of operands which are to be replaced. | |||
1142 | SmallVector<LSRFixup, 8> Fixups; | |||
1143 | ||||
1144 | /// Keep track of the min and max offsets of the fixups. | |||
1145 | int64_t MinOffset = std::numeric_limits<int64_t>::max(); | |||
1146 | int64_t MaxOffset = std::numeric_limits<int64_t>::min(); | |||
1147 | ||||
1148 | /// This records whether all of the fixups using this LSRUse are outside of | |||
1149 | /// the loop, in which case some special-case heuristics may be used. | |||
1150 | bool AllFixupsOutsideLoop = true; | |||
1151 | ||||
1152 | /// RigidFormula is set to true to guarantee that this use will be associated | |||
1153 | /// with a single formula--the one that initially matched. Some SCEV | |||
1154 | /// expressions cannot be expanded. This allows LSR to consider the registers | |||
1155 | /// used by those expressions without the need to expand them later after | |||
1156 | /// changing the formula. | |||
1157 | bool RigidFormula = false; | |||
1158 | ||||
1159 | /// This records the widest use type for any fixup using this | |||
1160 | /// LSRUse. FindUseWithSimilarFormula can't consider uses with different max | |||
1161 | /// fixup widths to be equivalent, because the narrower one may be relying on | |||
1162 | /// the implicit truncation to truncate away bogus bits. | |||
1163 | Type *WidestFixupType = nullptr; | |||
1164 | ||||
1165 | /// A list of ways to build a value that can satisfy this user. After the | |||
1166 | /// list is populated, one of these is selected heuristically and used to | |||
1167 | /// formulate a replacement for OperandValToReplace in UserInst. | |||
1168 | SmallVector<Formula, 12> Formulae; | |||
1169 | ||||
1170 | /// The set of register candidates used by all formulae in this LSRUse. | |||
1171 | SmallPtrSet<const SCEV *, 4> Regs; | |||
1172 | ||||
1173 | LSRUse(KindType K, MemAccessTy AT) : Kind(K), AccessTy(AT) {} | |||
1174 | ||||
1175 | LSRFixup &getNewFixup() { | |||
1176 | Fixups.push_back(LSRFixup()); | |||
1177 | return Fixups.back(); | |||
1178 | } | |||
1179 | ||||
1180 | void pushFixup(LSRFixup &f) { | |||
1181 | Fixups.push_back(f); | |||
1182 | if (f.Offset > MaxOffset) | |||
1183 | MaxOffset = f.Offset; | |||
1184 | if (f.Offset < MinOffset) | |||
1185 | MinOffset = f.Offset; | |||
1186 | } | |||
1187 | ||||
1188 | bool HasFormulaWithSameRegs(const Formula &F) const; | |||
1189 | float getNotSelectedProbability(const SCEV *Reg) const; | |||
1190 | bool InsertFormula(const Formula &F, const Loop &L); | |||
1191 | void DeleteFormula(Formula &F); | |||
1192 | void RecomputeRegs(size_t LUIdx, RegUseTracker &Reguses); | |||
1193 | ||||
1194 | void print(raw_ostream &OS) const; | |||
1195 | void dump() const; | |||
1196 | }; | |||
1197 | ||||
1198 | } // end anonymous namespace | |||
1199 | ||||
1200 | static bool isAMCompletelyFolded(const TargetTransformInfo &TTI, | |||
1201 | LSRUse::KindType Kind, MemAccessTy AccessTy, | |||
1202 | GlobalValue *BaseGV, int64_t BaseOffset, | |||
1203 | bool HasBaseReg, int64_t Scale, | |||
1204 | Instruction *Fixup = nullptr); | |||
1205 | ||||
1206 | /// Tally up interesting quantities from the given register. | |||
1207 | void Cost::RateRegister(const SCEV *Reg, | |||
1208 | SmallPtrSetImpl<const SCEV *> &Regs, | |||
1209 | const Loop *L, | |||
1210 | ScalarEvolution &SE, DominatorTree &DT, | |||
1211 | const TargetTransformInfo &TTI) { | |||
1212 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Reg)) { | |||
1213 | // If this is an addrec for another loop, it should be an invariant | |||
1214 | // with respect to L since L is the innermost loop (at least | |||
1215 | // for now LSR only handles innermost loops). | |||
1216 | if (AR->getLoop() != L) { | |||
1217 | // If the AddRec exists, consider it's register free and leave it alone. | |||
1218 | if (isExistingPhi(AR, SE)) | |||
1219 | return; | |||
1220 | ||||
1221 | // It is bad to allow LSR for current loop to add induction variables | |||
1222 | // for its sibling loops. | |||
1223 | if (!AR->getLoop()->contains(L)) { | |||
1224 | Lose(); | |||
1225 | return; | |||
1226 | } | |||
1227 | ||||
1228 | // Otherwise, it will be an invariant with respect to Loop L. | |||
1229 | ++C.NumRegs; | |||
1230 | return; | |||
1231 | } | |||
1232 | ||||
1233 | unsigned LoopCost = 1; | |||
1234 | if (TTI.shouldFavorPostInc()) { | |||
1235 | const SCEV *LoopStep = AR->getStepRecurrence(SE); | |||
1236 | if (isa<SCEVConstant>(LoopStep)) { | |||
1237 | // Check if a post-indexed load/store can be used. | |||
1238 | if (TTI.isIndexedLoadLegal(TTI.MIM_PostInc, AR->getType()) || | |||
1239 | TTI.isIndexedStoreLegal(TTI.MIM_PostInc, AR->getType())) { | |||
1240 | const SCEV *LoopStart = AR->getStart(); | |||
1241 | if (!isa<SCEVConstant>(LoopStart) && | |||
1242 | SE.isLoopInvariant(LoopStart, L)) | |||
1243 | LoopCost = 0; | |||
1244 | } | |||
1245 | } | |||
1246 | } | |||
1247 | C.AddRecCost += LoopCost; | |||
1248 | ||||
1249 | // Add the step value register, if it needs one. | |||
1250 | // TODO: The non-affine case isn't precisely modeled here. | |||
1251 | if (!AR->isAffine() || !isa<SCEVConstant>(AR->getOperand(1))) { | |||
1252 | if (!Regs.count(AR->getOperand(1))) { | |||
1253 | RateRegister(AR->getOperand(1), Regs, L, SE, DT, TTI); | |||
1254 | if (isLoser()) | |||
1255 | return; | |||
1256 | } | |||
1257 | } | |||
1258 | } | |||
1259 | ++C.NumRegs; | |||
1260 | ||||
1261 | // Rough heuristic; favor registers which don't require extra setup | |||
1262 | // instructions in the preheader. | |||
1263 | if (!isa<SCEVUnknown>(Reg) && | |||
1264 | !isa<SCEVConstant>(Reg) && | |||
1265 | !(isa<SCEVAddRecExpr>(Reg) && | |||
1266 | (isa<SCEVUnknown>(cast<SCEVAddRecExpr>(Reg)->getStart()) || | |||
1267 | isa<SCEVConstant>(cast<SCEVAddRecExpr>(Reg)->getStart())))) | |||
1268 | ++C.SetupCost; | |||
1269 | ||||
1270 | C.NumIVMuls += isa<SCEVMulExpr>(Reg) && | |||
1271 | SE.hasComputableLoopEvolution(Reg, L); | |||
1272 | } | |||
1273 | ||||
1274 | /// Record this register in the set. If we haven't seen it before, rate | |||
1275 | /// it. Optional LoserRegs provides a way to declare any formula that refers to | |||
1276 | /// one of those regs an instant loser. | |||
1277 | void Cost::RatePrimaryRegister(const SCEV *Reg, | |||
1278 | SmallPtrSetImpl<const SCEV *> &Regs, | |||
1279 | const Loop *L, | |||
1280 | ScalarEvolution &SE, DominatorTree &DT, | |||
1281 | SmallPtrSetImpl<const SCEV *> *LoserRegs, | |||
1282 | const TargetTransformInfo &TTI) { | |||
1283 | if (LoserRegs && LoserRegs->count(Reg)) { | |||
1284 | Lose(); | |||
1285 | return; | |||
1286 | } | |||
1287 | if (Regs.insert(Reg).second) { | |||
1288 | RateRegister(Reg, Regs, L, SE, DT, TTI); | |||
1289 | if (LoserRegs && isLoser()) | |||
1290 | LoserRegs->insert(Reg); | |||
1291 | } | |||
1292 | } | |||
1293 | ||||
1294 | void Cost::RateFormula(const TargetTransformInfo &TTI, | |||
1295 | const Formula &F, | |||
1296 | SmallPtrSetImpl<const SCEV *> &Regs, | |||
1297 | const DenseSet<const SCEV *> &VisitedRegs, | |||
1298 | const Loop *L, | |||
1299 | ScalarEvolution &SE, DominatorTree &DT, | |||
1300 | const LSRUse &LU, | |||
1301 | SmallPtrSetImpl<const SCEV *> *LoserRegs) { | |||
1302 | assert(F.isCanonical(*L) && "Cost is accurate only for canonical formula")(static_cast <bool> (F.isCanonical(*L) && "Cost is accurate only for canonical formula" ) ? void (0) : __assert_fail ("F.isCanonical(*L) && \"Cost is accurate only for canonical formula\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1302, __extension__ __PRETTY_FUNCTION__)); | |||
1303 | // Tally up the registers. | |||
1304 | unsigned PrevAddRecCost = C.AddRecCost; | |||
1305 | unsigned PrevNumRegs = C.NumRegs; | |||
1306 | unsigned PrevNumBaseAdds = C.NumBaseAdds; | |||
1307 | if (const SCEV *ScaledReg = F.ScaledReg) { | |||
1308 | if (VisitedRegs.count(ScaledReg)) { | |||
1309 | Lose(); | |||
1310 | return; | |||
1311 | } | |||
1312 | RatePrimaryRegister(ScaledReg, Regs, L, SE, DT, LoserRegs, TTI); | |||
1313 | if (isLoser()) | |||
1314 | return; | |||
1315 | } | |||
1316 | for (const SCEV *BaseReg : F.BaseRegs) { | |||
1317 | if (VisitedRegs.count(BaseReg)) { | |||
1318 | Lose(); | |||
1319 | return; | |||
1320 | } | |||
1321 | RatePrimaryRegister(BaseReg, Regs, L, SE, DT, LoserRegs, TTI); | |||
1322 | if (isLoser()) | |||
1323 | return; | |||
1324 | } | |||
1325 | ||||
1326 | // Determine how many (unfolded) adds we'll need inside the loop. | |||
1327 | size_t NumBaseParts = F.getNumRegs(); | |||
1328 | if (NumBaseParts > 1) | |||
1329 | // Do not count the base and a possible second register if the target | |||
1330 | // allows to fold 2 registers. | |||
1331 | C.NumBaseAdds += | |||
1332 | NumBaseParts - (1 + (F.Scale && isAMCompletelyFolded(TTI, LU, F))); | |||
1333 | C.NumBaseAdds += (F.UnfoldedOffset != 0); | |||
1334 | ||||
1335 | // Accumulate non-free scaling amounts. | |||
1336 | C.ScaleCost += getScalingFactorCost(TTI, LU, F, *L); | |||
1337 | ||||
1338 | // Tally up the non-zero immediates. | |||
1339 | for (const LSRFixup &Fixup : LU.Fixups) { | |||
1340 | int64_t O = Fixup.Offset; | |||
1341 | int64_t Offset = (uint64_t)O + F.BaseOffset; | |||
1342 | if (F.BaseGV) | |||
1343 | C.ImmCost += 64; // Handle symbolic values conservatively. | |||
1344 | // TODO: This should probably be the pointer size. | |||
1345 | else if (Offset != 0) | |||
1346 | C.ImmCost += APInt(64, Offset, true).getMinSignedBits(); | |||
1347 | ||||
1348 | // Check with target if this offset with this instruction is | |||
1349 | // specifically not supported. | |||
1350 | if (LU.Kind == LSRUse::Address && Offset != 0 && | |||
1351 | !isAMCompletelyFolded(TTI, LSRUse::Address, LU.AccessTy, F.BaseGV, | |||
1352 | Offset, F.HasBaseReg, F.Scale, Fixup.UserInst)) | |||
1353 | C.NumBaseAdds++; | |||
1354 | } | |||
1355 | ||||
1356 | // If we don't count instruction cost exit here. | |||
1357 | if (!InsnsCost) { | |||
1358 | assert(isValid() && "invalid cost")(static_cast <bool> (isValid() && "invalid cost" ) ? void (0) : __assert_fail ("isValid() && \"invalid cost\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1358, __extension__ __PRETTY_FUNCTION__)); | |||
1359 | return; | |||
1360 | } | |||
1361 | ||||
1362 | // Treat every new register that exceeds TTI.getNumberOfRegisters() - 1 as | |||
1363 | // additional instruction (at least fill). | |||
1364 | unsigned TTIRegNum = TTI.getNumberOfRegisters(false) - 1; | |||
1365 | if (C.NumRegs > TTIRegNum) { | |||
1366 | // Cost already exceeded TTIRegNum, then only newly added register can add | |||
1367 | // new instructions. | |||
1368 | if (PrevNumRegs > TTIRegNum) | |||
1369 | C.Insns += (C.NumRegs - PrevNumRegs); | |||
1370 | else | |||
1371 | C.Insns += (C.NumRegs - TTIRegNum); | |||
1372 | } | |||
1373 | ||||
1374 | // If ICmpZero formula ends with not 0, it could not be replaced by | |||
1375 | // just add or sub. We'll need to compare final result of AddRec. | |||
1376 | // That means we'll need an additional instruction. But if the target can | |||
1377 | // macro-fuse a compare with a branch, don't count this extra instruction. | |||
1378 | // For -10 + {0, +, 1}: | |||
1379 | // i = i + 1; | |||
1380 | // cmp i, 10 | |||
1381 | // | |||
1382 | // For {-10, +, 1}: | |||
1383 | // i = i + 1; | |||
1384 | if (LU.Kind == LSRUse::ICmpZero && !F.hasZeroEnd() && !TTI.canMacroFuseCmp()) | |||
1385 | C.Insns++; | |||
1386 | // Each new AddRec adds 1 instruction to calculation. | |||
1387 | C.Insns += (C.AddRecCost - PrevAddRecCost); | |||
1388 | ||||
1389 | // BaseAdds adds instructions for unfolded registers. | |||
1390 | if (LU.Kind != LSRUse::ICmpZero) | |||
1391 | C.Insns += C.NumBaseAdds - PrevNumBaseAdds; | |||
1392 | assert(isValid() && "invalid cost")(static_cast <bool> (isValid() && "invalid cost" ) ? void (0) : __assert_fail ("isValid() && \"invalid cost\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1392, __extension__ __PRETTY_FUNCTION__)); | |||
1393 | } | |||
1394 | ||||
1395 | /// Set this cost to a losing value. | |||
1396 | void Cost::Lose() { | |||
1397 | C.Insns = std::numeric_limits<unsigned>::max(); | |||
1398 | C.NumRegs = std::numeric_limits<unsigned>::max(); | |||
1399 | C.AddRecCost = std::numeric_limits<unsigned>::max(); | |||
1400 | C.NumIVMuls = std::numeric_limits<unsigned>::max(); | |||
1401 | C.NumBaseAdds = std::numeric_limits<unsigned>::max(); | |||
1402 | C.ImmCost = std::numeric_limits<unsigned>::max(); | |||
1403 | C.SetupCost = std::numeric_limits<unsigned>::max(); | |||
1404 | C.ScaleCost = std::numeric_limits<unsigned>::max(); | |||
1405 | } | |||
1406 | ||||
1407 | /// Choose the lower cost. | |||
1408 | bool Cost::isLess(Cost &Other, const TargetTransformInfo &TTI) { | |||
1409 | if (InsnsCost.getNumOccurrences() > 0 && InsnsCost && | |||
1410 | C.Insns != Other.C.Insns) | |||
1411 | return C.Insns < Other.C.Insns; | |||
1412 | return TTI.isLSRCostLess(C, Other.C); | |||
1413 | } | |||
1414 | ||||
1415 | #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) | |||
1416 | void Cost::print(raw_ostream &OS) const { | |||
1417 | if (InsnsCost) | |||
1418 | OS << C.Insns << " instruction" << (C.Insns == 1 ? " " : "s "); | |||
1419 | OS << C.NumRegs << " reg" << (C.NumRegs == 1 ? "" : "s"); | |||
1420 | if (C.AddRecCost != 0) | |||
1421 | OS << ", with addrec cost " << C.AddRecCost; | |||
1422 | if (C.NumIVMuls != 0) | |||
1423 | OS << ", plus " << C.NumIVMuls << " IV mul" | |||
1424 | << (C.NumIVMuls == 1 ? "" : "s"); | |||
1425 | if (C.NumBaseAdds != 0) | |||
1426 | OS << ", plus " << C.NumBaseAdds << " base add" | |||
1427 | << (C.NumBaseAdds == 1 ? "" : "s"); | |||
1428 | if (C.ScaleCost != 0) | |||
1429 | OS << ", plus " << C.ScaleCost << " scale cost"; | |||
1430 | if (C.ImmCost != 0) | |||
1431 | OS << ", plus " << C.ImmCost << " imm cost"; | |||
1432 | if (C.SetupCost != 0) | |||
1433 | OS << ", plus " << C.SetupCost << " setup cost"; | |||
1434 | } | |||
1435 | ||||
1436 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void Cost::dump() const { | |||
1437 | print(errs()); errs() << '\n'; | |||
1438 | } | |||
1439 | #endif | |||
1440 | ||||
1441 | /// Test whether this fixup always uses its value outside of the given loop. | |||
1442 | bool LSRFixup::isUseFullyOutsideLoop(const Loop *L) const { | |||
1443 | // PHI nodes use their value in their incoming blocks. | |||
1444 | if (const PHINode *PN = dyn_cast<PHINode>(UserInst)) { | |||
1445 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) | |||
1446 | if (PN->getIncomingValue(i) == OperandValToReplace && | |||
1447 | L->contains(PN->getIncomingBlock(i))) | |||
1448 | return false; | |||
1449 | return true; | |||
1450 | } | |||
1451 | ||||
1452 | return !L->contains(UserInst); | |||
1453 | } | |||
1454 | ||||
1455 | #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) | |||
1456 | void LSRFixup::print(raw_ostream &OS) const { | |||
1457 | OS << "UserInst="; | |||
1458 | // Store is common and interesting enough to be worth special-casing. | |||
1459 | if (StoreInst *Store = dyn_cast<StoreInst>(UserInst)) { | |||
1460 | OS << "store "; | |||
1461 | Store->getOperand(0)->printAsOperand(OS, /*PrintType=*/false); | |||
1462 | } else if (UserInst->getType()->isVoidTy()) | |||
1463 | OS << UserInst->getOpcodeName(); | |||
1464 | else | |||
1465 | UserInst->printAsOperand(OS, /*PrintType=*/false); | |||
1466 | ||||
1467 | OS << ", OperandValToReplace="; | |||
1468 | OperandValToReplace->printAsOperand(OS, /*PrintType=*/false); | |||
1469 | ||||
1470 | for (const Loop *PIL : PostIncLoops) { | |||
1471 | OS << ", PostIncLoop="; | |||
1472 | PIL->getHeader()->printAsOperand(OS, /*PrintType=*/false); | |||
1473 | } | |||
1474 | ||||
1475 | if (Offset != 0) | |||
1476 | OS << ", Offset=" << Offset; | |||
1477 | } | |||
1478 | ||||
1479 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void LSRFixup::dump() const { | |||
1480 | print(errs()); errs() << '\n'; | |||
1481 | } | |||
1482 | #endif | |||
1483 | ||||
1484 | /// Test whether this use as a formula which has the same registers as the given | |||
1485 | /// formula. | |||
1486 | bool LSRUse::HasFormulaWithSameRegs(const Formula &F) const { | |||
1487 | SmallVector<const SCEV *, 4> Key = F.BaseRegs; | |||
1488 | if (F.ScaledReg) Key.push_back(F.ScaledReg); | |||
1489 | // Unstable sort by host order ok, because this is only used for uniquifying. | |||
1490 | llvm::sort(Key.begin(), Key.end()); | |||
1491 | return Uniquifier.count(Key); | |||
1492 | } | |||
1493 | ||||
1494 | /// The function returns a probability of selecting formula without Reg. | |||
1495 | float LSRUse::getNotSelectedProbability(const SCEV *Reg) const { | |||
1496 | unsigned FNum = 0; | |||
1497 | for (const Formula &F : Formulae) | |||
1498 | if (F.referencesReg(Reg)) | |||
1499 | FNum++; | |||
1500 | return ((float)(Formulae.size() - FNum)) / Formulae.size(); | |||
1501 | } | |||
1502 | ||||
1503 | /// If the given formula has not yet been inserted, add it to the list, and | |||
1504 | /// return true. Return false otherwise. The formula must be in canonical form. | |||
1505 | bool LSRUse::InsertFormula(const Formula &F, const Loop &L) { | |||
1506 | assert(F.isCanonical(L) && "Invalid canonical representation")(static_cast <bool> (F.isCanonical(L) && "Invalid canonical representation" ) ? void (0) : __assert_fail ("F.isCanonical(L) && \"Invalid canonical representation\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1506, __extension__ __PRETTY_FUNCTION__)); | |||
1507 | ||||
1508 | if (!Formulae.empty() && RigidFormula) | |||
1509 | return false; | |||
1510 | ||||
1511 | SmallVector<const SCEV *, 4> Key = F.BaseRegs; | |||
1512 | if (F.ScaledReg) Key.push_back(F.ScaledReg); | |||
1513 | // Unstable sort by host order ok, because this is only used for uniquifying. | |||
1514 | llvm::sort(Key.begin(), Key.end()); | |||
1515 | ||||
1516 | if (!Uniquifier.insert(Key).second) | |||
1517 | return false; | |||
1518 | ||||
1519 | // Using a register to hold the value of 0 is not profitable. | |||
1520 | assert((!F.ScaledReg || !F.ScaledReg->isZero()) &&(static_cast <bool> ((!F.ScaledReg || !F.ScaledReg-> isZero()) && "Zero allocated in a scaled register!") ? void (0) : __assert_fail ("(!F.ScaledReg || !F.ScaledReg->isZero()) && \"Zero allocated in a scaled register!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1521, __extension__ __PRETTY_FUNCTION__)) | |||
1521 | "Zero allocated in a scaled register!")(static_cast <bool> ((!F.ScaledReg || !F.ScaledReg-> isZero()) && "Zero allocated in a scaled register!") ? void (0) : __assert_fail ("(!F.ScaledReg || !F.ScaledReg->isZero()) && \"Zero allocated in a scaled register!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1521, __extension__ __PRETTY_FUNCTION__)); | |||
1522 | #ifndef NDEBUG | |||
1523 | for (const SCEV *BaseReg : F.BaseRegs) | |||
1524 | assert(!BaseReg->isZero() && "Zero allocated in a base register!")(static_cast <bool> (!BaseReg->isZero() && "Zero allocated in a base register!" ) ? void (0) : __assert_fail ("!BaseReg->isZero() && \"Zero allocated in a base register!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1524, __extension__ __PRETTY_FUNCTION__)); | |||
1525 | #endif | |||
1526 | ||||
1527 | // Add the formula to the list. | |||
1528 | Formulae.push_back(F); | |||
1529 | ||||
1530 | // Record registers now being used by this use. | |||
1531 | Regs.insert(F.BaseRegs.begin(), F.BaseRegs.end()); | |||
1532 | if (F.ScaledReg) | |||
1533 | Regs.insert(F.ScaledReg); | |||
1534 | ||||
1535 | return true; | |||
1536 | } | |||
1537 | ||||
1538 | /// Remove the given formula from this use's list. | |||
1539 | void LSRUse::DeleteFormula(Formula &F) { | |||
1540 | if (&F != &Formulae.back()) | |||
1541 | std::swap(F, Formulae.back()); | |||
1542 | Formulae.pop_back(); | |||
1543 | } | |||
1544 | ||||
1545 | /// Recompute the Regs field, and update RegUses. | |||
1546 | void LSRUse::RecomputeRegs(size_t LUIdx, RegUseTracker &RegUses) { | |||
1547 | // Now that we've filtered out some formulae, recompute the Regs set. | |||
1548 | SmallPtrSet<const SCEV *, 4> OldRegs = std::move(Regs); | |||
1549 | Regs.clear(); | |||
1550 | for (const Formula &F : Formulae) { | |||
1551 | if (F.ScaledReg) Regs.insert(F.ScaledReg); | |||
1552 | Regs.insert(F.BaseRegs.begin(), F.BaseRegs.end()); | |||
1553 | } | |||
1554 | ||||
1555 | // Update the RegTracker. | |||
1556 | for (const SCEV *S : OldRegs) | |||
1557 | if (!Regs.count(S)) | |||
1558 | RegUses.dropRegister(S, LUIdx); | |||
1559 | } | |||
1560 | ||||
1561 | #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) | |||
1562 | void LSRUse::print(raw_ostream &OS) const { | |||
1563 | OS << "LSR Use: Kind="; | |||
1564 | switch (Kind) { | |||
1565 | case Basic: OS << "Basic"; break; | |||
1566 | case Special: OS << "Special"; break; | |||
1567 | case ICmpZero: OS << "ICmpZero"; break; | |||
1568 | case Address: | |||
1569 | OS << "Address of "; | |||
1570 | if (AccessTy.MemTy->isPointerTy()) | |||
1571 | OS << "pointer"; // the full pointer type could be really verbose | |||
1572 | else { | |||
1573 | OS << *AccessTy.MemTy; | |||
1574 | } | |||
1575 | ||||
1576 | OS << " in addrspace(" << AccessTy.AddrSpace << ')'; | |||
1577 | } | |||
1578 | ||||
1579 | OS << ", Offsets={"; | |||
1580 | bool NeedComma = false; | |||
1581 | for (const LSRFixup &Fixup : Fixups) { | |||
1582 | if (NeedComma) OS << ','; | |||
1583 | OS << Fixup.Offset; | |||
1584 | NeedComma = true; | |||
1585 | } | |||
1586 | OS << '}'; | |||
1587 | ||||
1588 | if (AllFixupsOutsideLoop) | |||
1589 | OS << ", all-fixups-outside-loop"; | |||
1590 | ||||
1591 | if (WidestFixupType) | |||
1592 | OS << ", widest fixup type: " << *WidestFixupType; | |||
1593 | } | |||
1594 | ||||
1595 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void LSRUse::dump() const { | |||
1596 | print(errs()); errs() << '\n'; | |||
1597 | } | |||
1598 | #endif | |||
1599 | ||||
1600 | static bool isAMCompletelyFolded(const TargetTransformInfo &TTI, | |||
1601 | LSRUse::KindType Kind, MemAccessTy AccessTy, | |||
1602 | GlobalValue *BaseGV, int64_t BaseOffset, | |||
1603 | bool HasBaseReg, int64_t Scale, | |||
1604 | Instruction *Fixup/*= nullptr*/) { | |||
1605 | switch (Kind) { | |||
1606 | case LSRUse::Address: | |||
1607 | return TTI.isLegalAddressingMode(AccessTy.MemTy, BaseGV, BaseOffset, | |||
1608 | HasBaseReg, Scale, AccessTy.AddrSpace, Fixup); | |||
1609 | ||||
1610 | case LSRUse::ICmpZero: | |||
1611 | // There's not even a target hook for querying whether it would be legal to | |||
1612 | // fold a GV into an ICmp. | |||
1613 | if (BaseGV) | |||
1614 | return false; | |||
1615 | ||||
1616 | // ICmp only has two operands; don't allow more than two non-trivial parts. | |||
1617 | if (Scale != 0 && HasBaseReg && BaseOffset != 0) | |||
1618 | return false; | |||
1619 | ||||
1620 | // ICmp only supports no scale or a -1 scale, as we can "fold" a -1 scale by | |||
1621 | // putting the scaled register in the other operand of the icmp. | |||
1622 | if (Scale != 0 && Scale != -1) | |||
1623 | return false; | |||
1624 | ||||
1625 | // If we have low-level target information, ask the target if it can fold an | |||
1626 | // integer immediate on an icmp. | |||
1627 | if (BaseOffset != 0) { | |||
1628 | // We have one of: | |||
1629 | // ICmpZero BaseReg + BaseOffset => ICmp BaseReg, -BaseOffset | |||
1630 | // ICmpZero -1*ScaleReg + BaseOffset => ICmp ScaleReg, BaseOffset | |||
1631 | // Offs is the ICmp immediate. | |||
1632 | if (Scale == 0) | |||
1633 | // The cast does the right thing with | |||
1634 | // std::numeric_limits<int64_t>::min(). | |||
1635 | BaseOffset = -(uint64_t)BaseOffset; | |||
1636 | return TTI.isLegalICmpImmediate(BaseOffset); | |||
1637 | } | |||
1638 | ||||
1639 | // ICmpZero BaseReg + -1*ScaleReg => ICmp BaseReg, ScaleReg | |||
1640 | return true; | |||
1641 | ||||
1642 | case LSRUse::Basic: | |||
1643 | // Only handle single-register values. | |||
1644 | return !BaseGV && Scale == 0 && BaseOffset == 0; | |||
1645 | ||||
1646 | case LSRUse::Special: | |||
1647 | // Special case Basic to handle -1 scales. | |||
1648 | return !BaseGV && (Scale == 0 || Scale == -1) && BaseOffset == 0; | |||
1649 | } | |||
1650 | ||||
1651 | llvm_unreachable("Invalid LSRUse Kind!")::llvm::llvm_unreachable_internal("Invalid LSRUse Kind!", "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1651); | |||
1652 | } | |||
1653 | ||||
1654 | static bool isAMCompletelyFolded(const TargetTransformInfo &TTI, | |||
1655 | int64_t MinOffset, int64_t MaxOffset, | |||
1656 | LSRUse::KindType Kind, MemAccessTy AccessTy, | |||
1657 | GlobalValue *BaseGV, int64_t BaseOffset, | |||
1658 | bool HasBaseReg, int64_t Scale) { | |||
1659 | // Check for overflow. | |||
1660 | if (((int64_t)((uint64_t)BaseOffset + MinOffset) > BaseOffset) != | |||
1661 | (MinOffset > 0)) | |||
1662 | return false; | |||
1663 | MinOffset = (uint64_t)BaseOffset + MinOffset; | |||
1664 | if (((int64_t)((uint64_t)BaseOffset + MaxOffset) > BaseOffset) != | |||
1665 | (MaxOffset > 0)) | |||
1666 | return false; | |||
1667 | MaxOffset = (uint64_t)BaseOffset + MaxOffset; | |||
1668 | ||||
1669 | return isAMCompletelyFolded(TTI, Kind, AccessTy, BaseGV, MinOffset, | |||
1670 | HasBaseReg, Scale) && | |||
1671 | isAMCompletelyFolded(TTI, Kind, AccessTy, BaseGV, MaxOffset, | |||
1672 | HasBaseReg, Scale); | |||
1673 | } | |||
1674 | ||||
1675 | static bool isAMCompletelyFolded(const TargetTransformInfo &TTI, | |||
1676 | int64_t MinOffset, int64_t MaxOffset, | |||
1677 | LSRUse::KindType Kind, MemAccessTy AccessTy, | |||
1678 | const Formula &F, const Loop &L) { | |||
1679 | // For the purpose of isAMCompletelyFolded either having a canonical formula | |||
1680 | // or a scale not equal to zero is correct. | |||
1681 | // Problems may arise from non canonical formulae having a scale == 0. | |||
1682 | // Strictly speaking it would best to just rely on canonical formulae. | |||
1683 | // However, when we generate the scaled formulae, we first check that the | |||
1684 | // scaling factor is profitable before computing the actual ScaledReg for | |||
1685 | // compile time sake. | |||
1686 | assert((F.isCanonical(L) || F.Scale != 0))(static_cast <bool> ((F.isCanonical(L) || F.Scale != 0) ) ? void (0) : __assert_fail ("(F.isCanonical(L) || F.Scale != 0)" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1686, __extension__ __PRETTY_FUNCTION__)); | |||
1687 | return isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy, | |||
1688 | F.BaseGV, F.BaseOffset, F.HasBaseReg, F.Scale); | |||
1689 | } | |||
1690 | ||||
1691 | /// Test whether we know how to expand the current formula. | |||
1692 | static bool isLegalUse(const TargetTransformInfo &TTI, int64_t MinOffset, | |||
1693 | int64_t MaxOffset, LSRUse::KindType Kind, | |||
1694 | MemAccessTy AccessTy, GlobalValue *BaseGV, | |||
1695 | int64_t BaseOffset, bool HasBaseReg, int64_t Scale) { | |||
1696 | // We know how to expand completely foldable formulae. | |||
1697 | return isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy, BaseGV, | |||
1698 | BaseOffset, HasBaseReg, Scale) || | |||
1699 | // Or formulae that use a base register produced by a sum of base | |||
1700 | // registers. | |||
1701 | (Scale == 1 && | |||
1702 | isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy, | |||
1703 | BaseGV, BaseOffset, true, 0)); | |||
1704 | } | |||
1705 | ||||
1706 | static bool isLegalUse(const TargetTransformInfo &TTI, int64_t MinOffset, | |||
1707 | int64_t MaxOffset, LSRUse::KindType Kind, | |||
1708 | MemAccessTy AccessTy, const Formula &F) { | |||
1709 | return isLegalUse(TTI, MinOffset, MaxOffset, Kind, AccessTy, F.BaseGV, | |||
1710 | F.BaseOffset, F.HasBaseReg, F.Scale); | |||
1711 | } | |||
1712 | ||||
1713 | static bool isAMCompletelyFolded(const TargetTransformInfo &TTI, | |||
1714 | const LSRUse &LU, const Formula &F) { | |||
1715 | // Target may want to look at the user instructions. | |||
1716 | if (LU.Kind == LSRUse::Address && TTI.LSRWithInstrQueries()) { | |||
1717 | for (const LSRFixup &Fixup : LU.Fixups) | |||
1718 | if (!isAMCompletelyFolded(TTI, LSRUse::Address, LU.AccessTy, F.BaseGV, | |||
1719 | (F.BaseOffset + Fixup.Offset), F.HasBaseReg, | |||
1720 | F.Scale, Fixup.UserInst)) | |||
1721 | return false; | |||
1722 | return true; | |||
1723 | } | |||
1724 | ||||
1725 | return isAMCompletelyFolded(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, | |||
1726 | LU.AccessTy, F.BaseGV, F.BaseOffset, F.HasBaseReg, | |||
1727 | F.Scale); | |||
1728 | } | |||
1729 | ||||
1730 | static unsigned getScalingFactorCost(const TargetTransformInfo &TTI, | |||
1731 | const LSRUse &LU, const Formula &F, | |||
1732 | const Loop &L) { | |||
1733 | if (!F.Scale) | |||
1734 | return 0; | |||
1735 | ||||
1736 | // If the use is not completely folded in that instruction, we will have to | |||
1737 | // pay an extra cost only for scale != 1. | |||
1738 | if (!isAMCompletelyFolded(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, | |||
1739 | LU.AccessTy, F, L)) | |||
1740 | return F.Scale != 1; | |||
1741 | ||||
1742 | switch (LU.Kind) { | |||
1743 | case LSRUse::Address: { | |||
1744 | // Check the scaling factor cost with both the min and max offsets. | |||
1745 | int ScaleCostMinOffset = TTI.getScalingFactorCost( | |||
1746 | LU.AccessTy.MemTy, F.BaseGV, F.BaseOffset + LU.MinOffset, F.HasBaseReg, | |||
1747 | F.Scale, LU.AccessTy.AddrSpace); | |||
1748 | int ScaleCostMaxOffset = TTI.getScalingFactorCost( | |||
1749 | LU.AccessTy.MemTy, F.BaseGV, F.BaseOffset + LU.MaxOffset, F.HasBaseReg, | |||
1750 | F.Scale, LU.AccessTy.AddrSpace); | |||
1751 | ||||
1752 | assert(ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >= 0 &&(static_cast <bool> (ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >= 0 && "Legal addressing mode has an illegal cost!" ) ? void (0) : __assert_fail ("ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >= 0 && \"Legal addressing mode has an illegal cost!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1753, __extension__ __PRETTY_FUNCTION__)) | |||
1753 | "Legal addressing mode has an illegal cost!")(static_cast <bool> (ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >= 0 && "Legal addressing mode has an illegal cost!" ) ? void (0) : __assert_fail ("ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >= 0 && \"Legal addressing mode has an illegal cost!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1753, __extension__ __PRETTY_FUNCTION__)); | |||
1754 | return std::max(ScaleCostMinOffset, ScaleCostMaxOffset); | |||
1755 | } | |||
1756 | case LSRUse::ICmpZero: | |||
1757 | case LSRUse::Basic: | |||
1758 | case LSRUse::Special: | |||
1759 | // The use is completely folded, i.e., everything is folded into the | |||
1760 | // instruction. | |||
1761 | return 0; | |||
1762 | } | |||
1763 | ||||
1764 | llvm_unreachable("Invalid LSRUse Kind!")::llvm::llvm_unreachable_internal("Invalid LSRUse Kind!", "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1764); | |||
1765 | } | |||
1766 | ||||
1767 | static bool isAlwaysFoldable(const TargetTransformInfo &TTI, | |||
1768 | LSRUse::KindType Kind, MemAccessTy AccessTy, | |||
1769 | GlobalValue *BaseGV, int64_t BaseOffset, | |||
1770 | bool HasBaseReg) { | |||
1771 | // Fast-path: zero is always foldable. | |||
1772 | if (BaseOffset == 0 && !BaseGV) return true; | |||
1773 | ||||
1774 | // Conservatively, create an address with an immediate and a | |||
1775 | // base and a scale. | |||
1776 | int64_t Scale = Kind == LSRUse::ICmpZero ? -1 : 1; | |||
1777 | ||||
1778 | // Canonicalize a scale of 1 to a base register if the formula doesn't | |||
1779 | // already have a base register. | |||
1780 | if (!HasBaseReg && Scale == 1) { | |||
1781 | Scale = 0; | |||
1782 | HasBaseReg = true; | |||
1783 | } | |||
1784 | ||||
1785 | return isAMCompletelyFolded(TTI, Kind, AccessTy, BaseGV, BaseOffset, | |||
1786 | HasBaseReg, Scale); | |||
1787 | } | |||
1788 | ||||
1789 | static bool isAlwaysFoldable(const TargetTransformInfo &TTI, | |||
1790 | ScalarEvolution &SE, int64_t MinOffset, | |||
1791 | int64_t MaxOffset, LSRUse::KindType Kind, | |||
1792 | MemAccessTy AccessTy, const SCEV *S, | |||
1793 | bool HasBaseReg) { | |||
1794 | // Fast-path: zero is always foldable. | |||
1795 | if (S->isZero()) return true; | |||
1796 | ||||
1797 | // Conservatively, create an address with an immediate and a | |||
1798 | // base and a scale. | |||
1799 | int64_t BaseOffset = ExtractImmediate(S, SE); | |||
1800 | GlobalValue *BaseGV = ExtractSymbol(S, SE); | |||
1801 | ||||
1802 | // If there's anything else involved, it's not foldable. | |||
1803 | if (!S->isZero()) return false; | |||
1804 | ||||
1805 | // Fast-path: zero is always foldable. | |||
1806 | if (BaseOffset == 0 && !BaseGV) return true; | |||
1807 | ||||
1808 | // Conservatively, create an address with an immediate and a | |||
1809 | // base and a scale. | |||
1810 | int64_t Scale = Kind == LSRUse::ICmpZero ? -1 : 1; | |||
1811 | ||||
1812 | return isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy, BaseGV, | |||
1813 | BaseOffset, HasBaseReg, Scale); | |||
1814 | } | |||
1815 | ||||
1816 | namespace { | |||
1817 | ||||
1818 | /// An individual increment in a Chain of IV increments. Relate an IV user to | |||
1819 | /// an expression that computes the IV it uses from the IV used by the previous | |||
1820 | /// link in the Chain. | |||
1821 | /// | |||
1822 | /// For the head of a chain, IncExpr holds the absolute SCEV expression for the | |||
1823 | /// original IVOperand. The head of the chain's IVOperand is only valid during | |||
1824 | /// chain collection, before LSR replaces IV users. During chain generation, | |||
1825 | /// IncExpr can be used to find the new IVOperand that computes the same | |||
1826 | /// expression. | |||
1827 | struct IVInc { | |||
1828 | Instruction *UserInst; | |||
1829 | Value* IVOperand; | |||
1830 | const SCEV *IncExpr; | |||
1831 | ||||
1832 | IVInc(Instruction *U, Value *O, const SCEV *E) | |||
1833 | : UserInst(U), IVOperand(O), IncExpr(E) {} | |||
1834 | }; | |||
1835 | ||||
1836 | // The list of IV increments in program order. We typically add the head of a | |||
1837 | // chain without finding subsequent links. | |||
1838 | struct IVChain { | |||
1839 | SmallVector<IVInc, 1> Incs; | |||
1840 | const SCEV *ExprBase = nullptr; | |||
1841 | ||||
1842 | IVChain() = default; | |||
1843 | IVChain(const IVInc &Head, const SCEV *Base) | |||
1844 | : Incs(1, Head), ExprBase(Base) {} | |||
1845 | ||||
1846 | using const_iterator = SmallVectorImpl<IVInc>::const_iterator; | |||
1847 | ||||
1848 | // Return the first increment in the chain. | |||
1849 | const_iterator begin() const { | |||
1850 | assert(!Incs.empty())(static_cast <bool> (!Incs.empty()) ? void (0) : __assert_fail ("!Incs.empty()", "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 1850, __extension__ __PRETTY_FUNCTION__)); | |||
1851 | return std::next(Incs.begin()); | |||
1852 | } | |||
1853 | const_iterator end() const { | |||
1854 | return Incs.end(); | |||
1855 | } | |||
1856 | ||||
1857 | // Returns true if this chain contains any increments. | |||
1858 | bool hasIncs() const { return Incs.size() >= 2; } | |||
1859 | ||||
1860 | // Add an IVInc to the end of this chain. | |||
1861 | void add(const IVInc &X) { Incs.push_back(X); } | |||
1862 | ||||
1863 | // Returns the last UserInst in the chain. | |||
1864 | Instruction *tailUserInst() const { return Incs.back().UserInst; } | |||
1865 | ||||
1866 | // Returns true if IncExpr can be profitably added to this chain. | |||
1867 | bool isProfitableIncrement(const SCEV *OperExpr, | |||
1868 | const SCEV *IncExpr, | |||
1869 | ScalarEvolution&); | |||
1870 | }; | |||
1871 | ||||
1872 | /// Helper for CollectChains to track multiple IV increment uses. Distinguish | |||
1873 | /// between FarUsers that definitely cross IV increments and NearUsers that may | |||
1874 | /// be used between IV increments. | |||
1875 | struct ChainUsers { | |||
1876 | SmallPtrSet<Instruction*, 4> FarUsers; | |||
1877 | SmallPtrSet<Instruction*, 4> NearUsers; | |||
1878 | }; | |||
1879 | ||||
1880 | /// This class holds state for the main loop strength reduction logic. | |||
1881 | class LSRInstance { | |||
1882 | IVUsers &IU; | |||
1883 | ScalarEvolution &SE; | |||
1884 | DominatorTree &DT; | |||
1885 | LoopInfo &LI; | |||
1886 | const TargetTransformInfo &TTI; | |||
1887 | Loop *const L; | |||
1888 | bool Changed = false; | |||
1889 | ||||
1890 | /// This is the insert position that the current loop's induction variable | |||
1891 | /// increment should be placed. In simple loops, this is the latch block's | |||
1892 | /// terminator. But in more complicated cases, this is a position which will | |||
1893 | /// dominate all the in-loop post-increment users. | |||
1894 | Instruction *IVIncInsertPos = nullptr; | |||
1895 | ||||
1896 | /// Interesting factors between use strides. | |||
1897 | /// | |||
1898 | /// We explicitly use a SetVector which contains a SmallSet, instead of the | |||
1899 | /// default, a SmallDenseSet, because we need to use the full range of | |||
1900 | /// int64_ts, and there's currently no good way of doing that with | |||
1901 | /// SmallDenseSet. | |||
1902 | SetVector<int64_t, SmallVector<int64_t, 8>, SmallSet<int64_t, 8>> Factors; | |||
1903 | ||||
1904 | /// Interesting use types, to facilitate truncation reuse. | |||
1905 | SmallSetVector<Type *, 4> Types; | |||
1906 | ||||
1907 | /// The list of interesting uses. | |||
1908 | SmallVector<LSRUse, 16> Uses; | |||
1909 | ||||
1910 | /// Track which uses use which register candidates. | |||
1911 | RegUseTracker RegUses; | |||
1912 | ||||
1913 | // Limit the number of chains to avoid quadratic behavior. We don't expect to | |||
1914 | // have more than a few IV increment chains in a loop. Missing a Chain falls | |||
1915 | // back to normal LSR behavior for those uses. | |||
1916 | static const unsigned MaxChains = 8; | |||
1917 | ||||
1918 | /// IV users can form a chain of IV increments. | |||
1919 | SmallVector<IVChain, MaxChains> IVChainVec; | |||
1920 | ||||
1921 | /// IV users that belong to profitable IVChains. | |||
1922 | SmallPtrSet<Use*, MaxChains> IVIncSet; | |||
1923 | ||||
1924 | void OptimizeShadowIV(); | |||
1925 | bool FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse); | |||
1926 | ICmpInst *OptimizeMax(ICmpInst *Cond, IVStrideUse* &CondUse); | |||
1927 | void OptimizeLoopTermCond(); | |||
1928 | ||||
1929 | void ChainInstruction(Instruction *UserInst, Instruction *IVOper, | |||
1930 | SmallVectorImpl<ChainUsers> &ChainUsersVec); | |||
1931 | void FinalizeChain(IVChain &Chain); | |||
1932 | void CollectChains(); | |||
1933 | void GenerateIVChain(const IVChain &Chain, SCEVExpander &Rewriter, | |||
1934 | SmallVectorImpl<WeakTrackingVH> &DeadInsts); | |||
1935 | ||||
1936 | void CollectInterestingTypesAndFactors(); | |||
1937 | void CollectFixupsAndInitialFormulae(); | |||
1938 | ||||
1939 | // Support for sharing of LSRUses between LSRFixups. | |||
1940 | using UseMapTy = DenseMap<LSRUse::SCEVUseKindPair, size_t>; | |||
1941 | UseMapTy UseMap; | |||
1942 | ||||
1943 | bool reconcileNewOffset(LSRUse &LU, int64_t NewOffset, bool HasBaseReg, | |||
1944 | LSRUse::KindType Kind, MemAccessTy AccessTy); | |||
1945 | ||||
1946 | std::pair<size_t, int64_t> getUse(const SCEV *&Expr, LSRUse::KindType Kind, | |||
1947 | MemAccessTy AccessTy); | |||
1948 | ||||
1949 | void DeleteUse(LSRUse &LU, size_t LUIdx); | |||
1950 | ||||
1951 | LSRUse *FindUseWithSimilarFormula(const Formula &F, const LSRUse &OrigLU); | |||
1952 | ||||
1953 | void InsertInitialFormula(const SCEV *S, LSRUse &LU, size_t LUIdx); | |||
1954 | void InsertSupplementalFormula(const SCEV *S, LSRUse &LU, size_t LUIdx); | |||
1955 | void CountRegisters(const Formula &F, size_t LUIdx); | |||
1956 | bool InsertFormula(LSRUse &LU, unsigned LUIdx, const Formula &F); | |||
1957 | ||||
1958 | void CollectLoopInvariantFixupsAndFormulae(); | |||
1959 | ||||
1960 | void GenerateReassociations(LSRUse &LU, unsigned LUIdx, Formula Base, | |||
1961 | unsigned Depth = 0); | |||
1962 | ||||
1963 | void GenerateReassociationsImpl(LSRUse &LU, unsigned LUIdx, | |||
1964 | const Formula &Base, unsigned Depth, | |||
1965 | size_t Idx, bool IsScaledReg = false); | |||
1966 | void GenerateCombinations(LSRUse &LU, unsigned LUIdx, Formula Base); | |||
1967 | void GenerateSymbolicOffsetsImpl(LSRUse &LU, unsigned LUIdx, | |||
1968 | const Formula &Base, size_t Idx, | |||
1969 | bool IsScaledReg = false); | |||
1970 | void GenerateSymbolicOffsets(LSRUse &LU, unsigned LUIdx, Formula Base); | |||
1971 | void GenerateConstantOffsetsImpl(LSRUse &LU, unsigned LUIdx, | |||
1972 | const Formula &Base, | |||
1973 | const SmallVectorImpl<int64_t> &Worklist, | |||
1974 | size_t Idx, bool IsScaledReg = false); | |||
1975 | void GenerateConstantOffsets(LSRUse &LU, unsigned LUIdx, Formula Base); | |||
1976 | void GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx, Formula Base); | |||
1977 | void GenerateScales(LSRUse &LU, unsigned LUIdx, Formula Base); | |||
1978 | void GenerateTruncates(LSRUse &LU, unsigned LUIdx, Formula Base); | |||
1979 | void GenerateCrossUseConstantOffsets(); | |||
1980 | void GenerateAllReuseFormulae(); | |||
1981 | ||||
1982 | void FilterOutUndesirableDedicatedRegisters(); | |||
1983 | ||||
1984 | size_t EstimateSearchSpaceComplexity() const; | |||
1985 | void NarrowSearchSpaceByDetectingSupersets(); | |||
1986 | void NarrowSearchSpaceByCollapsingUnrolledCode(); | |||
1987 | void NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters(); | |||
1988 | void NarrowSearchSpaceByFilterFormulaWithSameScaledReg(); | |||
1989 | void NarrowSearchSpaceByDeletingCostlyFormulas(); | |||
1990 | void NarrowSearchSpaceByPickingWinnerRegs(); | |||
1991 | void NarrowSearchSpaceUsingHeuristics(); | |||
1992 | ||||
1993 | void SolveRecurse(SmallVectorImpl<const Formula *> &Solution, | |||
1994 | Cost &SolutionCost, | |||
1995 | SmallVectorImpl<const Formula *> &Workspace, | |||
1996 | const Cost &CurCost, | |||
1997 | const SmallPtrSet<const SCEV *, 16> &CurRegs, | |||
1998 | DenseSet<const SCEV *> &VisitedRegs) const; | |||
1999 | void Solve(SmallVectorImpl<const Formula *> &Solution) const; | |||
2000 | ||||
2001 | BasicBlock::iterator | |||
2002 | HoistInsertPosition(BasicBlock::iterator IP, | |||
2003 | const SmallVectorImpl<Instruction *> &Inputs) const; | |||
2004 | BasicBlock::iterator | |||
2005 | AdjustInsertPositionForExpand(BasicBlock::iterator IP, | |||
2006 | const LSRFixup &LF, | |||
2007 | const LSRUse &LU, | |||
2008 | SCEVExpander &Rewriter) const; | |||
2009 | ||||
2010 | Value *Expand(const LSRUse &LU, const LSRFixup &LF, const Formula &F, | |||
2011 | BasicBlock::iterator IP, SCEVExpander &Rewriter, | |||
2012 | SmallVectorImpl<WeakTrackingVH> &DeadInsts) const; | |||
2013 | void RewriteForPHI(PHINode *PN, const LSRUse &LU, const LSRFixup &LF, | |||
2014 | const Formula &F, SCEVExpander &Rewriter, | |||
2015 | SmallVectorImpl<WeakTrackingVH> &DeadInsts) const; | |||
2016 | void Rewrite(const LSRUse &LU, const LSRFixup &LF, const Formula &F, | |||
2017 | SCEVExpander &Rewriter, | |||
2018 | SmallVectorImpl<WeakTrackingVH> &DeadInsts) const; | |||
2019 | void ImplementSolution(const SmallVectorImpl<const Formula *> &Solution); | |||
2020 | ||||
2021 | public: | |||
2022 | LSRInstance(Loop *L, IVUsers &IU, ScalarEvolution &SE, DominatorTree &DT, | |||
2023 | LoopInfo &LI, const TargetTransformInfo &TTI); | |||
2024 | ||||
2025 | bool getChanged() const { return Changed; } | |||
2026 | ||||
2027 | void print_factors_and_types(raw_ostream &OS) const; | |||
2028 | void print_fixups(raw_ostream &OS) const; | |||
2029 | void print_uses(raw_ostream &OS) const; | |||
2030 | void print(raw_ostream &OS) const; | |||
2031 | void dump() const; | |||
2032 | }; | |||
2033 | ||||
2034 | } // end anonymous namespace | |||
2035 | ||||
2036 | /// If IV is used in a int-to-float cast inside the loop then try to eliminate | |||
2037 | /// the cast operation. | |||
2038 | void LSRInstance::OptimizeShadowIV() { | |||
2039 | const SCEV *BackedgeTakenCount = SE.getBackedgeTakenCount(L); | |||
2040 | if (isa<SCEVCouldNotCompute>(BackedgeTakenCount)) | |||
2041 | return; | |||
2042 | ||||
2043 | for (IVUsers::const_iterator UI = IU.begin(), E = IU.end(); | |||
2044 | UI != E; /* empty */) { | |||
2045 | IVUsers::const_iterator CandidateUI = UI; | |||
2046 | ++UI; | |||
2047 | Instruction *ShadowUse = CandidateUI->getUser(); | |||
2048 | Type *DestTy = nullptr; | |||
2049 | bool IsSigned = false; | |||
2050 | ||||
2051 | /* If shadow use is a int->float cast then insert a second IV | |||
2052 | to eliminate this cast. | |||
2053 | ||||
2054 | for (unsigned i = 0; i < n; ++i) | |||
2055 | foo((double)i); | |||
2056 | ||||
2057 | is transformed into | |||
2058 | ||||
2059 | double d = 0.0; | |||
2060 | for (unsigned i = 0; i < n; ++i, ++d) | |||
2061 | foo(d); | |||
2062 | */ | |||
2063 | if (UIToFPInst *UCast = dyn_cast<UIToFPInst>(CandidateUI->getUser())) { | |||
2064 | IsSigned = false; | |||
2065 | DestTy = UCast->getDestTy(); | |||
2066 | } | |||
2067 | else if (SIToFPInst *SCast = dyn_cast<SIToFPInst>(CandidateUI->getUser())) { | |||
2068 | IsSigned = true; | |||
2069 | DestTy = SCast->getDestTy(); | |||
2070 | } | |||
2071 | if (!DestTy) continue; | |||
2072 | ||||
2073 | // If target does not support DestTy natively then do not apply | |||
2074 | // this transformation. | |||
2075 | if (!TTI.isTypeLegal(DestTy)) continue; | |||
2076 | ||||
2077 | PHINode *PH = dyn_cast<PHINode>(ShadowUse->getOperand(0)); | |||
2078 | if (!PH) continue; | |||
2079 | if (PH->getNumIncomingValues() != 2) continue; | |||
2080 | ||||
2081 | // If the calculation in integers overflows, the result in FP type will | |||
2082 | // differ. So we only can do this transformation if we are guaranteed to not | |||
2083 | // deal with overflowing values | |||
2084 | const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(SE.getSCEV(PH)); | |||
2085 | if (!AR) continue; | |||
2086 | if (IsSigned && !AR->hasNoSignedWrap()) continue; | |||
2087 | if (!IsSigned && !AR->hasNoUnsignedWrap()) continue; | |||
2088 | ||||
2089 | Type *SrcTy = PH->getType(); | |||
2090 | int Mantissa = DestTy->getFPMantissaWidth(); | |||
2091 | if (Mantissa == -1) continue; | |||
2092 | if ((int)SE.getTypeSizeInBits(SrcTy) > Mantissa) | |||
2093 | continue; | |||
2094 | ||||
2095 | unsigned Entry, Latch; | |||
2096 | if (PH->getIncomingBlock(0) == L->getLoopPreheader()) { | |||
2097 | Entry = 0; | |||
2098 | Latch = 1; | |||
2099 | } else { | |||
2100 | Entry = 1; | |||
2101 | Latch = 0; | |||
2102 | } | |||
2103 | ||||
2104 | ConstantInt *Init = dyn_cast<ConstantInt>(PH->getIncomingValue(Entry)); | |||
2105 | if (!Init) continue; | |||
2106 | Constant *NewInit = ConstantFP::get(DestTy, IsSigned ? | |||
2107 | (double)Init->getSExtValue() : | |||
2108 | (double)Init->getZExtValue()); | |||
2109 | ||||
2110 | BinaryOperator *Incr = | |||
2111 | dyn_cast<BinaryOperator>(PH->getIncomingValue(Latch)); | |||
2112 | if (!Incr) continue; | |||
2113 | if (Incr->getOpcode() != Instruction::Add | |||
2114 | && Incr->getOpcode() != Instruction::Sub) | |||
2115 | continue; | |||
2116 | ||||
2117 | /* Initialize new IV, double d = 0.0 in above example. */ | |||
2118 | ConstantInt *C = nullptr; | |||
2119 | if (Incr->getOperand(0) == PH) | |||
2120 | C = dyn_cast<ConstantInt>(Incr->getOperand(1)); | |||
2121 | else if (Incr->getOperand(1) == PH) | |||
2122 | C = dyn_cast<ConstantInt>(Incr->getOperand(0)); | |||
2123 | else | |||
2124 | continue; | |||
2125 | ||||
2126 | if (!C) continue; | |||
2127 | ||||
2128 | // Ignore negative constants, as the code below doesn't handle them | |||
2129 | // correctly. TODO: Remove this restriction. | |||
2130 | if (!C->getValue().isStrictlyPositive()) continue; | |||
2131 | ||||
2132 | /* Add new PHINode. */ | |||
2133 | PHINode *NewPH = PHINode::Create(DestTy, 2, "IV.S.", PH); | |||
2134 | ||||
2135 | /* create new increment. '++d' in above example. */ | |||
2136 | Constant *CFP = ConstantFP::get(DestTy, C->getZExtValue()); | |||
2137 | BinaryOperator *NewIncr = | |||
2138 | BinaryOperator::Create(Incr->getOpcode() == Instruction::Add ? | |||
2139 | Instruction::FAdd : Instruction::FSub, | |||
2140 | NewPH, CFP, "IV.S.next.", Incr); | |||
2141 | ||||
2142 | NewPH->addIncoming(NewInit, PH->getIncomingBlock(Entry)); | |||
2143 | NewPH->addIncoming(NewIncr, PH->getIncomingBlock(Latch)); | |||
2144 | ||||
2145 | /* Remove cast operation */ | |||
2146 | ShadowUse->replaceAllUsesWith(NewPH); | |||
2147 | ShadowUse->eraseFromParent(); | |||
2148 | Changed = true; | |||
2149 | break; | |||
2150 | } | |||
2151 | } | |||
2152 | ||||
2153 | /// If Cond has an operand that is an expression of an IV, set the IV user and | |||
2154 | /// stride information and return true, otherwise return false. | |||
2155 | bool LSRInstance::FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse) { | |||
2156 | for (IVStrideUse &U : IU) | |||
2157 | if (U.getUser() == Cond) { | |||
2158 | // NOTE: we could handle setcc instructions with multiple uses here, but | |||
2159 | // InstCombine does it as well for simple uses, it's not clear that it | |||
2160 | // occurs enough in real life to handle. | |||
2161 | CondUse = &U; | |||
2162 | return true; | |||
2163 | } | |||
2164 | return false; | |||
2165 | } | |||
2166 | ||||
2167 | /// Rewrite the loop's terminating condition if it uses a max computation. | |||
2168 | /// | |||
2169 | /// This is a narrow solution to a specific, but acute, problem. For loops | |||
2170 | /// like this: | |||
2171 | /// | |||
2172 | /// i = 0; | |||
2173 | /// do { | |||
2174 | /// p[i] = 0.0; | |||
2175 | /// } while (++i < n); | |||
2176 | /// | |||
2177 | /// the trip count isn't just 'n', because 'n' might not be positive. And | |||
2178 | /// unfortunately this can come up even for loops where the user didn't use | |||
2179 | /// a C do-while loop. For example, seemingly well-behaved top-test loops | |||
2180 | /// will commonly be lowered like this: | |||
2181 | /// | |||
2182 | /// if (n > 0) { | |||
2183 | /// i = 0; | |||
2184 | /// do { | |||
2185 | /// p[i] = 0.0; | |||
2186 | /// } while (++i < n); | |||
2187 | /// } | |||
2188 | /// | |||
2189 | /// and then it's possible for subsequent optimization to obscure the if | |||
2190 | /// test in such a way that indvars can't find it. | |||
2191 | /// | |||
2192 | /// When indvars can't find the if test in loops like this, it creates a | |||
2193 | /// max expression, which allows it to give the loop a canonical | |||
2194 | /// induction variable: | |||
2195 | /// | |||
2196 | /// i = 0; | |||
2197 | /// max = n < 1 ? 1 : n; | |||
2198 | /// do { | |||
2199 | /// p[i] = 0.0; | |||
2200 | /// } while (++i != max); | |||
2201 | /// | |||
2202 | /// Canonical induction variables are necessary because the loop passes | |||
2203 | /// are designed around them. The most obvious example of this is the | |||
2204 | /// LoopInfo analysis, which doesn't remember trip count values. It | |||
2205 | /// expects to be able to rediscover the trip count each time it is | |||
2206 | /// needed, and it does this using a simple analysis that only succeeds if | |||
2207 | /// the loop has a canonical induction variable. | |||
2208 | /// | |||
2209 | /// However, when it comes time to generate code, the maximum operation | |||
2210 | /// can be quite costly, especially if it's inside of an outer loop. | |||
2211 | /// | |||
2212 | /// This function solves this problem by detecting this type of loop and | |||
2213 | /// rewriting their conditions from ICMP_NE back to ICMP_SLT, and deleting | |||
2214 | /// the instructions for the maximum computation. | |||
2215 | ICmpInst *LSRInstance::OptimizeMax(ICmpInst *Cond, IVStrideUse* &CondUse) { | |||
2216 | // Check that the loop matches the pattern we're looking for. | |||
2217 | if (Cond->getPredicate() != CmpInst::ICMP_EQ && | |||
2218 | Cond->getPredicate() != CmpInst::ICMP_NE) | |||
2219 | return Cond; | |||
2220 | ||||
2221 | SelectInst *Sel = dyn_cast<SelectInst>(Cond->getOperand(1)); | |||
2222 | if (!Sel || !Sel->hasOneUse()) return Cond; | |||
2223 | ||||
2224 | const SCEV *BackedgeTakenCount = SE.getBackedgeTakenCount(L); | |||
2225 | if (isa<SCEVCouldNotCompute>(BackedgeTakenCount)) | |||
2226 | return Cond; | |||
2227 | const SCEV *One = SE.getConstant(BackedgeTakenCount->getType(), 1); | |||
2228 | ||||
2229 | // Add one to the backedge-taken count to get the trip count. | |||
2230 | const SCEV *IterationCount = SE.getAddExpr(One, BackedgeTakenCount); | |||
2231 | if (IterationCount != SE.getSCEV(Sel)) return Cond; | |||
2232 | ||||
2233 | // Check for a max calculation that matches the pattern. There's no check | |||
2234 | // for ICMP_ULE here because the comparison would be with zero, which | |||
2235 | // isn't interesting. | |||
2236 | CmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE; | |||
2237 | const SCEVNAryExpr *Max = nullptr; | |||
2238 | if (const SCEVSMaxExpr *S = dyn_cast<SCEVSMaxExpr>(BackedgeTakenCount)) { | |||
2239 | Pred = ICmpInst::ICMP_SLE; | |||
2240 | Max = S; | |||
2241 | } else if (const SCEVSMaxExpr *S = dyn_cast<SCEVSMaxExpr>(IterationCount)) { | |||
2242 | Pred = ICmpInst::ICMP_SLT; | |||
2243 | Max = S; | |||
2244 | } else if (const SCEVUMaxExpr *U = dyn_cast<SCEVUMaxExpr>(IterationCount)) { | |||
2245 | Pred = ICmpInst::ICMP_ULT; | |||
2246 | Max = U; | |||
2247 | } else { | |||
2248 | // No match; bail. | |||
2249 | return Cond; | |||
2250 | } | |||
2251 | ||||
2252 | // To handle a max with more than two operands, this optimization would | |||
2253 | // require additional checking and setup. | |||
2254 | if (Max->getNumOperands() != 2) | |||
2255 | return Cond; | |||
2256 | ||||
2257 | const SCEV *MaxLHS = Max->getOperand(0); | |||
2258 | const SCEV *MaxRHS = Max->getOperand(1); | |||
2259 | ||||
2260 | // ScalarEvolution canonicalizes constants to the left. For < and >, look | |||
2261 | // for a comparison with 1. For <= and >=, a comparison with zero. | |||
2262 | if (!MaxLHS || | |||
2263 | (ICmpInst::isTrueWhenEqual(Pred) ? !MaxLHS->isZero() : (MaxLHS != One))) | |||
2264 | return Cond; | |||
2265 | ||||
2266 | // Check the relevant induction variable for conformance to | |||
2267 | // the pattern. | |||
2268 | const SCEV *IV = SE.getSCEV(Cond->getOperand(0)); | |||
2269 | const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(IV); | |||
2270 | if (!AR || !AR->isAffine() || | |||
2271 | AR->getStart() != One || | |||
2272 | AR->getStepRecurrence(SE) != One) | |||
2273 | return Cond; | |||
2274 | ||||
2275 | assert(AR->getLoop() == L &&(static_cast <bool> (AR->getLoop() == L && "Loop condition operand is an addrec in a different loop!" ) ? void (0) : __assert_fail ("AR->getLoop() == L && \"Loop condition operand is an addrec in a different loop!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 2276, __extension__ __PRETTY_FUNCTION__)) | |||
2276 | "Loop condition operand is an addrec in a different loop!")(static_cast <bool> (AR->getLoop() == L && "Loop condition operand is an addrec in a different loop!" ) ? void (0) : __assert_fail ("AR->getLoop() == L && \"Loop condition operand is an addrec in a different loop!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 2276, __extension__ __PRETTY_FUNCTION__)); | |||
2277 | ||||
2278 | // Check the right operand of the select, and remember it, as it will | |||
2279 | // be used in the new comparison instruction. | |||
2280 | Value *NewRHS = nullptr; | |||
2281 | if (ICmpInst::isTrueWhenEqual(Pred)) { | |||
2282 | // Look for n+1, and grab n. | |||
2283 | if (AddOperator *BO = dyn_cast<AddOperator>(Sel->getOperand(1))) | |||
2284 | if (ConstantInt *BO1 = dyn_cast<ConstantInt>(BO->getOperand(1))) | |||
2285 | if (BO1->isOne() && SE.getSCEV(BO->getOperand(0)) == MaxRHS) | |||
2286 | NewRHS = BO->getOperand(0); | |||
2287 | if (AddOperator *BO = dyn_cast<AddOperator>(Sel->getOperand(2))) | |||
2288 | if (ConstantInt *BO1 = dyn_cast<ConstantInt>(BO->getOperand(1))) | |||
2289 | if (BO1->isOne() && SE.getSCEV(BO->getOperand(0)) == MaxRHS) | |||
2290 | NewRHS = BO->getOperand(0); | |||
2291 | if (!NewRHS) | |||
2292 | return Cond; | |||
2293 | } else if (SE.getSCEV(Sel->getOperand(1)) == MaxRHS) | |||
2294 | NewRHS = Sel->getOperand(1); | |||
2295 | else if (SE.getSCEV(Sel->getOperand(2)) == MaxRHS) | |||
2296 | NewRHS = Sel->getOperand(2); | |||
2297 | else if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(MaxRHS)) | |||
2298 | NewRHS = SU->getValue(); | |||
2299 | else | |||
2300 | // Max doesn't match expected pattern. | |||
2301 | return Cond; | |||
2302 | ||||
2303 | // Determine the new comparison opcode. It may be signed or unsigned, | |||
2304 | // and the original comparison may be either equality or inequality. | |||
2305 | if (Cond->getPredicate() == CmpInst::ICMP_EQ) | |||
2306 | Pred = CmpInst::getInversePredicate(Pred); | |||
2307 | ||||
2308 | // Ok, everything looks ok to change the condition into an SLT or SGE and | |||
2309 | // delete the max calculation. | |||
2310 | ICmpInst *NewCond = | |||
2311 | new ICmpInst(Cond, Pred, Cond->getOperand(0), NewRHS, "scmp"); | |||
2312 | ||||
2313 | // Delete the max calculation instructions. | |||
2314 | Cond->replaceAllUsesWith(NewCond); | |||
2315 | CondUse->setUser(NewCond); | |||
2316 | Instruction *Cmp = cast<Instruction>(Sel->getOperand(0)); | |||
2317 | Cond->eraseFromParent(); | |||
2318 | Sel->eraseFromParent(); | |||
2319 | if (Cmp->use_empty()) | |||
2320 | Cmp->eraseFromParent(); | |||
2321 | return NewCond; | |||
2322 | } | |||
2323 | ||||
2324 | /// Change loop terminating condition to use the postinc iv when possible. | |||
2325 | void | |||
2326 | LSRInstance::OptimizeLoopTermCond() { | |||
2327 | SmallPtrSet<Instruction *, 4> PostIncs; | |||
2328 | ||||
2329 | // We need a different set of heuristics for rotated and non-rotated loops. | |||
2330 | // If a loop is rotated then the latch is also the backedge, so inserting | |||
2331 | // post-inc expressions just before the latch is ideal. To reduce live ranges | |||
2332 | // it also makes sense to rewrite terminating conditions to use post-inc | |||
2333 | // expressions. | |||
2334 | // | |||
2335 | // If the loop is not rotated then the latch is not a backedge; the latch | |||
2336 | // check is done in the loop head. Adding post-inc expressions before the | |||
2337 | // latch will cause overlapping live-ranges of pre-inc and post-inc expressions | |||
2338 | // in the loop body. In this case we do *not* want to use post-inc expressions | |||
2339 | // in the latch check, and we want to insert post-inc expressions before | |||
2340 | // the backedge. | |||
2341 | BasicBlock *LatchBlock = L->getLoopLatch(); | |||
2342 | SmallVector<BasicBlock*, 8> ExitingBlocks; | |||
2343 | L->getExitingBlocks(ExitingBlocks); | |||
2344 | if (llvm::all_of(ExitingBlocks, [&LatchBlock](const BasicBlock *BB) { | |||
2345 | return LatchBlock != BB; | |||
2346 | })) { | |||
2347 | // The backedge doesn't exit the loop; treat this as a head-tested loop. | |||
2348 | IVIncInsertPos = LatchBlock->getTerminator(); | |||
2349 | return; | |||
2350 | } | |||
2351 | ||||
2352 | // Otherwise treat this as a rotated loop. | |||
2353 | for (BasicBlock *ExitingBlock : ExitingBlocks) { | |||
2354 | // Get the terminating condition for the loop if possible. If we | |||
2355 | // can, we want to change it to use a post-incremented version of its | |||
2356 | // induction variable, to allow coalescing the live ranges for the IV into | |||
2357 | // one register value. | |||
2358 | ||||
2359 | BranchInst *TermBr = dyn_cast<BranchInst>(ExitingBlock->getTerminator()); | |||
2360 | if (!TermBr) | |||
2361 | continue; | |||
2362 | // FIXME: Overly conservative, termination condition could be an 'or' etc.. | |||
2363 | if (TermBr->isUnconditional() || !isa<ICmpInst>(TermBr->getCondition())) | |||
2364 | continue; | |||
2365 | ||||
2366 | // Search IVUsesByStride to find Cond's IVUse if there is one. | |||
2367 | IVStrideUse *CondUse = nullptr; | |||
2368 | ICmpInst *Cond = cast<ICmpInst>(TermBr->getCondition()); | |||
2369 | if (!FindIVUserForCond(Cond, CondUse)) | |||
2370 | continue; | |||
2371 | ||||
2372 | // If the trip count is computed in terms of a max (due to ScalarEvolution | |||
2373 | // being unable to find a sufficient guard, for example), change the loop | |||
2374 | // comparison to use SLT or ULT instead of NE. | |||
2375 | // One consequence of doing this now is that it disrupts the count-down | |||
2376 | // optimization. That's not always a bad thing though, because in such | |||
2377 | // cases it may still be worthwhile to avoid a max. | |||
2378 | Cond = OptimizeMax(Cond, CondUse); | |||
2379 | ||||
2380 | // If this exiting block dominates the latch block, it may also use | |||
2381 | // the post-inc value if it won't be shared with other uses. | |||
2382 | // Check for dominance. | |||
2383 | if (!DT.dominates(ExitingBlock, LatchBlock)) | |||
2384 | continue; | |||
2385 | ||||
2386 | // Conservatively avoid trying to use the post-inc value in non-latch | |||
2387 | // exits if there may be pre-inc users in intervening blocks. | |||
2388 | if (LatchBlock != ExitingBlock) | |||
2389 | for (IVUsers::const_iterator UI = IU.begin(), E = IU.end(); UI != E; ++UI) | |||
2390 | // Test if the use is reachable from the exiting block. This dominator | |||
2391 | // query is a conservative approximation of reachability. | |||
2392 | if (&*UI != CondUse && | |||
2393 | !DT.properlyDominates(UI->getUser()->getParent(), ExitingBlock)) { | |||
2394 | // Conservatively assume there may be reuse if the quotient of their | |||
2395 | // strides could be a legal scale. | |||
2396 | const SCEV *A = IU.getStride(*CondUse, L); | |||
2397 | const SCEV *B = IU.getStride(*UI, L); | |||
2398 | if (!A || !B) continue; | |||
2399 | if (SE.getTypeSizeInBits(A->getType()) != | |||
2400 | SE.getTypeSizeInBits(B->getType())) { | |||
2401 | if (SE.getTypeSizeInBits(A->getType()) > | |||
2402 | SE.getTypeSizeInBits(B->getType())) | |||
2403 | B = SE.getSignExtendExpr(B, A->getType()); | |||
2404 | else | |||
2405 | A = SE.getSignExtendExpr(A, B->getType()); | |||
2406 | } | |||
2407 | if (const SCEVConstant *D = | |||
2408 | dyn_cast_or_null<SCEVConstant>(getExactSDiv(B, A, SE))) { | |||
2409 | const ConstantInt *C = D->getValue(); | |||
2410 | // Stride of one or negative one can have reuse with non-addresses. | |||
2411 | if (C->isOne() || C->isMinusOne()) | |||
2412 | goto decline_post_inc; | |||
2413 | // Avoid weird situations. | |||
2414 | if (C->getValue().getMinSignedBits() >= 64 || | |||
2415 | C->getValue().isMinSignedValue()) | |||
2416 | goto decline_post_inc; | |||
2417 | // Check for possible scaled-address reuse. | |||
2418 | if (isAddressUse(TTI, UI->getUser(), UI->getOperandValToReplace())) { | |||
2419 | MemAccessTy AccessTy = getAccessType( | |||
2420 | TTI, UI->getUser(), UI->getOperandValToReplace()); | |||
2421 | int64_t Scale = C->getSExtValue(); | |||
2422 | if (TTI.isLegalAddressingMode(AccessTy.MemTy, /*BaseGV=*/nullptr, | |||
2423 | /*BaseOffset=*/0, | |||
2424 | /*HasBaseReg=*/false, Scale, | |||
2425 | AccessTy.AddrSpace)) | |||
2426 | goto decline_post_inc; | |||
2427 | Scale = -Scale; | |||
2428 | if (TTI.isLegalAddressingMode(AccessTy.MemTy, /*BaseGV=*/nullptr, | |||
2429 | /*BaseOffset=*/0, | |||
2430 | /*HasBaseReg=*/false, Scale, | |||
2431 | AccessTy.AddrSpace)) | |||
2432 | goto decline_post_inc; | |||
2433 | } | |||
2434 | } | |||
2435 | } | |||
2436 | ||||
2437 | LLVM_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) | |||
2438 | << *Cond << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Change loop exiting icmp to use postinc iv: " << *Cond << '\n'; } } while (false); | |||
2439 | ||||
2440 | // It's possible for the setcc instruction to be anywhere in the loop, and | |||
2441 | // possible for it to have multiple users. If it is not immediately before | |||
2442 | // the exiting block branch, move it. | |||
2443 | if (&*++BasicBlock::iterator(Cond) != TermBr) { | |||
2444 | if (Cond->hasOneUse()) { | |||
2445 | Cond->moveBefore(TermBr); | |||
2446 | } else { | |||
2447 | // Clone the terminating condition and insert into the loopend. | |||
2448 | ICmpInst *OldCond = Cond; | |||
2449 | Cond = cast<ICmpInst>(Cond->clone()); | |||
2450 | Cond->setName(L->getHeader()->getName() + ".termcond"); | |||
2451 | ExitingBlock->getInstList().insert(TermBr->getIterator(), Cond); | |||
2452 | ||||
2453 | // Clone the IVUse, as the old use still exists! | |||
2454 | CondUse = &IU.AddUser(Cond, CondUse->getOperandValToReplace()); | |||
2455 | TermBr->replaceUsesOfWith(OldCond, Cond); | |||
2456 | } | |||
2457 | } | |||
2458 | ||||
2459 | // If we get to here, we know that we can transform the setcc instruction to | |||
2460 | // use the post-incremented version of the IV, allowing us to coalesce the | |||
2461 | // live ranges for the IV correctly. | |||
2462 | CondUse->transformToPostInc(L); | |||
2463 | Changed = true; | |||
2464 | ||||
2465 | PostIncs.insert(Cond); | |||
2466 | decline_post_inc:; | |||
2467 | } | |||
2468 | ||||
2469 | // Determine an insertion point for the loop induction variable increment. It | |||
2470 | // must dominate all the post-inc comparisons we just set up, and it must | |||
2471 | // dominate the loop latch edge. | |||
2472 | IVIncInsertPos = L->getLoopLatch()->getTerminator(); | |||
2473 | for (Instruction *Inst : PostIncs) { | |||
2474 | BasicBlock *BB = | |||
2475 | DT.findNearestCommonDominator(IVIncInsertPos->getParent(), | |||
2476 | Inst->getParent()); | |||
2477 | if (BB == Inst->getParent()) | |||
2478 | IVIncInsertPos = Inst; | |||
2479 | else if (BB != IVIncInsertPos->getParent()) | |||
2480 | IVIncInsertPos = BB->getTerminator(); | |||
2481 | } | |||
2482 | } | |||
2483 | ||||
2484 | /// Determine if the given use can accommodate a fixup at the given offset and | |||
2485 | /// other details. If so, update the use and return true. | |||
2486 | bool LSRInstance::reconcileNewOffset(LSRUse &LU, int64_t NewOffset, | |||
2487 | bool HasBaseReg, LSRUse::KindType Kind, | |||
2488 | MemAccessTy AccessTy) { | |||
2489 | int64_t NewMinOffset = LU.MinOffset; | |||
2490 | int64_t NewMaxOffset = LU.MaxOffset; | |||
2491 | MemAccessTy NewAccessTy = AccessTy; | |||
2492 | ||||
2493 | // Check for a mismatched kind. It's tempting to collapse mismatched kinds to | |||
2494 | // something conservative, however this can pessimize in the case that one of | |||
2495 | // the uses will have all its uses outside the loop, for example. | |||
2496 | if (LU.Kind != Kind) | |||
2497 | return false; | |||
2498 | ||||
2499 | // Check for a mismatched access type, and fall back conservatively as needed. | |||
2500 | // TODO: Be less conservative when the type is similar and can use the same | |||
2501 | // addressing modes. | |||
2502 | if (Kind == LSRUse::Address) { | |||
2503 | if (AccessTy.MemTy != LU.AccessTy.MemTy) { | |||
2504 | NewAccessTy = MemAccessTy::getUnknown(AccessTy.MemTy->getContext(), | |||
2505 | AccessTy.AddrSpace); | |||
2506 | } | |||
2507 | } | |||
2508 | ||||
2509 | // Conservatively assume HasBaseReg is true for now. | |||
2510 | if (NewOffset < LU.MinOffset) { | |||
2511 | if (!isAlwaysFoldable(TTI, Kind, NewAccessTy, /*BaseGV=*/nullptr, | |||
2512 | LU.MaxOffset - NewOffset, HasBaseReg)) | |||
2513 | return false; | |||
2514 | NewMinOffset = NewOffset; | |||
2515 | } else if (NewOffset > LU.MaxOffset) { | |||
2516 | if (!isAlwaysFoldable(TTI, Kind, NewAccessTy, /*BaseGV=*/nullptr, | |||
2517 | NewOffset - LU.MinOffset, HasBaseReg)) | |||
2518 | return false; | |||
2519 | NewMaxOffset = NewOffset; | |||
2520 | } | |||
2521 | ||||
2522 | // Update the use. | |||
2523 | LU.MinOffset = NewMinOffset; | |||
2524 | LU.MaxOffset = NewMaxOffset; | |||
2525 | LU.AccessTy = NewAccessTy; | |||
2526 | return true; | |||
2527 | } | |||
2528 | ||||
2529 | /// Return an LSRUse index and an offset value for a fixup which needs the given | |||
2530 | /// expression, with the given kind and optional access type. Either reuse an | |||
2531 | /// existing use or create a new one, as needed. | |||
2532 | std::pair<size_t, int64_t> LSRInstance::getUse(const SCEV *&Expr, | |||
2533 | LSRUse::KindType Kind, | |||
2534 | MemAccessTy AccessTy) { | |||
2535 | const SCEV *Copy = Expr; | |||
2536 | int64_t Offset = ExtractImmediate(Expr, SE); | |||
2537 | ||||
2538 | // Basic uses can't accept any offset, for example. | |||
2539 | if (!isAlwaysFoldable(TTI, Kind, AccessTy, /*BaseGV=*/ nullptr, | |||
2540 | Offset, /*HasBaseReg=*/ true)) { | |||
2541 | Expr = Copy; | |||
2542 | Offset = 0; | |||
2543 | } | |||
2544 | ||||
2545 | std::pair<UseMapTy::iterator, bool> P = | |||
2546 | UseMap.insert(std::make_pair(LSRUse::SCEVUseKindPair(Expr, Kind), 0)); | |||
2547 | if (!P.second) { | |||
2548 | // A use already existed with this base. | |||
2549 | size_t LUIdx = P.first->second; | |||
2550 | LSRUse &LU = Uses[LUIdx]; | |||
2551 | if (reconcileNewOffset(LU, Offset, /*HasBaseReg=*/true, Kind, AccessTy)) | |||
2552 | // Reuse this use. | |||
2553 | return std::make_pair(LUIdx, Offset); | |||
2554 | } | |||
2555 | ||||
2556 | // Create a new use. | |||
2557 | size_t LUIdx = Uses.size(); | |||
2558 | P.first->second = LUIdx; | |||
2559 | Uses.push_back(LSRUse(Kind, AccessTy)); | |||
2560 | LSRUse &LU = Uses[LUIdx]; | |||
2561 | ||||
2562 | LU.MinOffset = Offset; | |||
2563 | LU.MaxOffset = Offset; | |||
2564 | return std::make_pair(LUIdx, Offset); | |||
2565 | } | |||
2566 | ||||
2567 | /// Delete the given use from the Uses list. | |||
2568 | void LSRInstance::DeleteUse(LSRUse &LU, size_t LUIdx) { | |||
2569 | if (&LU != &Uses.back()) | |||
2570 | std::swap(LU, Uses.back()); | |||
2571 | Uses.pop_back(); | |||
2572 | ||||
2573 | // Update RegUses. | |||
2574 | RegUses.swapAndDropUse(LUIdx, Uses.size()); | |||
2575 | } | |||
2576 | ||||
2577 | /// Look for a use distinct from OrigLU which is has a formula that has the same | |||
2578 | /// registers as the given formula. | |||
2579 | LSRUse * | |||
2580 | LSRInstance::FindUseWithSimilarFormula(const Formula &OrigF, | |||
2581 | const LSRUse &OrigLU) { | |||
2582 | // Search all uses for the formula. This could be more clever. | |||
2583 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { | |||
2584 | LSRUse &LU = Uses[LUIdx]; | |||
2585 | // Check whether this use is close enough to OrigLU, to see whether it's | |||
2586 | // worthwhile looking through its formulae. | |||
2587 | // Ignore ICmpZero uses because they may contain formulae generated by | |||
2588 | // GenerateICmpZeroScales, in which case adding fixup offsets may | |||
2589 | // be invalid. | |||
2590 | if (&LU != &OrigLU && | |||
2591 | LU.Kind != LSRUse::ICmpZero && | |||
2592 | LU.Kind == OrigLU.Kind && OrigLU.AccessTy == LU.AccessTy && | |||
2593 | LU.WidestFixupType == OrigLU.WidestFixupType && | |||
2594 | LU.HasFormulaWithSameRegs(OrigF)) { | |||
2595 | // Scan through this use's formulae. | |||
2596 | for (const Formula &F : LU.Formulae) { | |||
2597 | // Check to see if this formula has the same registers and symbols | |||
2598 | // as OrigF. | |||
2599 | if (F.BaseRegs == OrigF.BaseRegs && | |||
2600 | F.ScaledReg == OrigF.ScaledReg && | |||
2601 | F.BaseGV == OrigF.BaseGV && | |||
2602 | F.Scale == OrigF.Scale && | |||
2603 | F.UnfoldedOffset == OrigF.UnfoldedOffset) { | |||
2604 | if (F.BaseOffset == 0) | |||
2605 | return &LU; | |||
2606 | // This is the formula where all the registers and symbols matched; | |||
2607 | // there aren't going to be any others. Since we declined it, we | |||
2608 | // can skip the rest of the formulae and proceed to the next LSRUse. | |||
2609 | break; | |||
2610 | } | |||
2611 | } | |||
2612 | } | |||
2613 | } | |||
2614 | ||||
2615 | // Nothing looked good. | |||
2616 | return nullptr; | |||
2617 | } | |||
2618 | ||||
2619 | void LSRInstance::CollectInterestingTypesAndFactors() { | |||
2620 | SmallSetVector<const SCEV *, 4> Strides; | |||
2621 | ||||
2622 | // Collect interesting types and strides. | |||
2623 | SmallVector<const SCEV *, 4> Worklist; | |||
2624 | for (const IVStrideUse &U : IU) { | |||
2625 | const SCEV *Expr = IU.getExpr(U); | |||
2626 | ||||
2627 | // Collect interesting types. | |||
2628 | Types.insert(SE.getEffectiveSCEVType(Expr->getType())); | |||
2629 | ||||
2630 | // Add strides for mentioned loops. | |||
2631 | Worklist.push_back(Expr); | |||
2632 | do { | |||
2633 | const SCEV *S = Worklist.pop_back_val(); | |||
2634 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) { | |||
2635 | if (AR->getLoop() == L) | |||
2636 | Strides.insert(AR->getStepRecurrence(SE)); | |||
2637 | Worklist.push_back(AR->getStart()); | |||
2638 | } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) { | |||
2639 | Worklist.append(Add->op_begin(), Add->op_end()); | |||
2640 | } | |||
2641 | } while (!Worklist.empty()); | |||
2642 | } | |||
2643 | ||||
2644 | // Compute interesting factors from the set of interesting strides. | |||
2645 | for (SmallSetVector<const SCEV *, 4>::const_iterator | |||
2646 | I = Strides.begin(), E = Strides.end(); I != E; ++I) | |||
2647 | for (SmallSetVector<const SCEV *, 4>::const_iterator NewStrideIter = | |||
2648 | std::next(I); NewStrideIter != E; ++NewStrideIter) { | |||
2649 | const SCEV *OldStride = *I; | |||
2650 | const SCEV *NewStride = *NewStrideIter; | |||
2651 | ||||
2652 | if (SE.getTypeSizeInBits(OldStride->getType()) != | |||
2653 | SE.getTypeSizeInBits(NewStride->getType())) { | |||
2654 | if (SE.getTypeSizeInBits(OldStride->getType()) > | |||
2655 | SE.getTypeSizeInBits(NewStride->getType())) | |||
2656 | NewStride = SE.getSignExtendExpr(NewStride, OldStride->getType()); | |||
2657 | else | |||
2658 | OldStride = SE.getSignExtendExpr(OldStride, NewStride->getType()); | |||
2659 | } | |||
2660 | if (const SCEVConstant *Factor = | |||
2661 | dyn_cast_or_null<SCEVConstant>(getExactSDiv(NewStride, OldStride, | |||
2662 | SE, true))) { | |||
2663 | if (Factor->getAPInt().getMinSignedBits() <= 64) | |||
2664 | Factors.insert(Factor->getAPInt().getSExtValue()); | |||
2665 | } else if (const SCEVConstant *Factor = | |||
2666 | dyn_cast_or_null<SCEVConstant>(getExactSDiv(OldStride, | |||
2667 | NewStride, | |||
2668 | SE, true))) { | |||
2669 | if (Factor->getAPInt().getMinSignedBits() <= 64) | |||
2670 | Factors.insert(Factor->getAPInt().getSExtValue()); | |||
2671 | } | |||
2672 | } | |||
2673 | ||||
2674 | // If all uses use the same type, don't bother looking for truncation-based | |||
2675 | // reuse. | |||
2676 | if (Types.size() == 1) | |||
2677 | Types.clear(); | |||
2678 | ||||
2679 | LLVM_DEBUG(print_factors_and_types(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { print_factors_and_types(dbgs()); } } while (false); | |||
2680 | } | |||
2681 | ||||
2682 | /// Helper for CollectChains that finds an IV operand (computed by an AddRec in | |||
2683 | /// this loop) within [OI,OE) or returns OE. If IVUsers mapped Instructions to | |||
2684 | /// IVStrideUses, we could partially skip this. | |||
2685 | static User::op_iterator | |||
2686 | findIVOperand(User::op_iterator OI, User::op_iterator OE, | |||
2687 | Loop *L, ScalarEvolution &SE) { | |||
2688 | for(; OI != OE; ++OI) { | |||
2689 | if (Instruction *Oper = dyn_cast<Instruction>(*OI)) { | |||
2690 | if (!SE.isSCEVable(Oper->getType())) | |||
2691 | continue; | |||
2692 | ||||
2693 | if (const SCEVAddRecExpr *AR = | |||
2694 | dyn_cast<SCEVAddRecExpr>(SE.getSCEV(Oper))) { | |||
2695 | if (AR->getLoop() == L) | |||
2696 | break; | |||
2697 | } | |||
2698 | } | |||
2699 | } | |||
2700 | return OI; | |||
2701 | } | |||
2702 | ||||
2703 | /// IVChain logic must consistently peek base TruncInst operands, so wrap it in | |||
2704 | /// a convenient helper. | |||
2705 | static Value *getWideOperand(Value *Oper) { | |||
2706 | if (TruncInst *Trunc = dyn_cast<TruncInst>(Oper)) | |||
2707 | return Trunc->getOperand(0); | |||
2708 | return Oper; | |||
2709 | } | |||
2710 | ||||
2711 | /// Return true if we allow an IV chain to include both types. | |||
2712 | static bool isCompatibleIVType(Value *LVal, Value *RVal) { | |||
2713 | Type *LType = LVal->getType(); | |||
2714 | Type *RType = RVal->getType(); | |||
2715 | return (LType == RType) || (LType->isPointerTy() && RType->isPointerTy() && | |||
2716 | // Different address spaces means (possibly) | |||
2717 | // different types of the pointer implementation, | |||
2718 | // e.g. i16 vs i32 so disallow that. | |||
2719 | (LType->getPointerAddressSpace() == | |||
2720 | RType->getPointerAddressSpace())); | |||
2721 | } | |||
2722 | ||||
2723 | /// Return an approximation of this SCEV expression's "base", or NULL for any | |||
2724 | /// constant. Returning the expression itself is conservative. Returning a | |||
2725 | /// deeper subexpression is more precise and valid as long as it isn't less | |||
2726 | /// complex than another subexpression. For expressions involving multiple | |||
2727 | /// unscaled values, we need to return the pointer-type SCEVUnknown. This avoids | |||
2728 | /// forming chains across objects, such as: PrevOper==a[i], IVOper==b[i], | |||
2729 | /// IVInc==b-a. | |||
2730 | /// | |||
2731 | /// Since SCEVUnknown is the rightmost type, and pointers are the rightmost | |||
2732 | /// SCEVUnknown, we simply return the rightmost SCEV operand. | |||
2733 | static const SCEV *getExprBase(const SCEV *S) { | |||
2734 | switch (S->getSCEVType()) { | |||
2735 | default: // uncluding scUnknown. | |||
2736 | return S; | |||
2737 | case scConstant: | |||
2738 | return nullptr; | |||
2739 | case scTruncate: | |||
2740 | return getExprBase(cast<SCEVTruncateExpr>(S)->getOperand()); | |||
2741 | case scZeroExtend: | |||
2742 | return getExprBase(cast<SCEVZeroExtendExpr>(S)->getOperand()); | |||
2743 | case scSignExtend: | |||
2744 | return getExprBase(cast<SCEVSignExtendExpr>(S)->getOperand()); | |||
2745 | case scAddExpr: { | |||
2746 | // Skip over scaled operands (scMulExpr) to follow add operands as long as | |||
2747 | // there's nothing more complex. | |||
2748 | // FIXME: not sure if we want to recognize negation. | |||
2749 | const SCEVAddExpr *Add = cast<SCEVAddExpr>(S); | |||
2750 | for (std::reverse_iterator<SCEVAddExpr::op_iterator> I(Add->op_end()), | |||
2751 | E(Add->op_begin()); I != E; ++I) { | |||
2752 | const SCEV *SubExpr = *I; | |||
2753 | if (SubExpr->getSCEVType() == scAddExpr) | |||
2754 | return getExprBase(SubExpr); | |||
2755 | ||||
2756 | if (SubExpr->getSCEVType() != scMulExpr) | |||
2757 | return SubExpr; | |||
2758 | } | |||
2759 | return S; // all operands are scaled, be conservative. | |||
2760 | } | |||
2761 | case scAddRecExpr: | |||
2762 | return getExprBase(cast<SCEVAddRecExpr>(S)->getStart()); | |||
2763 | } | |||
2764 | } | |||
2765 | ||||
2766 | /// Return true if the chain increment is profitable to expand into a loop | |||
2767 | /// invariant value, which may require its own register. A profitable chain | |||
2768 | /// increment will be an offset relative to the same base. We allow such offsets | |||
2769 | /// to potentially be used as chain increment as long as it's not obviously | |||
2770 | /// expensive to expand using real instructions. | |||
2771 | bool IVChain::isProfitableIncrement(const SCEV *OperExpr, | |||
2772 | const SCEV *IncExpr, | |||
2773 | ScalarEvolution &SE) { | |||
2774 | // Aggressively form chains when -stress-ivchain. | |||
2775 | if (StressIVChain) | |||
2776 | return true; | |||
2777 | ||||
2778 | // Do not replace a constant offset from IV head with a nonconstant IV | |||
2779 | // increment. | |||
2780 | if (!isa<SCEVConstant>(IncExpr)) { | |||
2781 | const SCEV *HeadExpr = SE.getSCEV(getWideOperand(Incs[0].IVOperand)); | |||
2782 | if (isa<SCEVConstant>(SE.getMinusSCEV(OperExpr, HeadExpr))) | |||
2783 | return false; | |||
2784 | } | |||
2785 | ||||
2786 | SmallPtrSet<const SCEV*, 8> Processed; | |||
2787 | return !isHighCostExpansion(IncExpr, Processed, SE); | |||
2788 | } | |||
2789 | ||||
2790 | /// Return true if the number of registers needed for the chain is estimated to | |||
2791 | /// be less than the number required for the individual IV users. First prohibit | |||
2792 | /// any IV users that keep the IV live across increments (the Users set should | |||
2793 | /// be empty). Next count the number and type of increments in the chain. | |||
2794 | /// | |||
2795 | /// Chaining IVs can lead to considerable code bloat if ISEL doesn't | |||
2796 | /// effectively use postinc addressing modes. Only consider it profitable it the | |||
2797 | /// increments can be computed in fewer registers when chained. | |||
2798 | /// | |||
2799 | /// TODO: Consider IVInc free if it's already used in another chains. | |||
2800 | static bool | |||
2801 | isProfitableChain(IVChain &Chain, SmallPtrSetImpl<Instruction*> &Users, | |||
2802 | ScalarEvolution &SE, const TargetTransformInfo &TTI) { | |||
2803 | if (StressIVChain) | |||
2804 | return true; | |||
2805 | ||||
2806 | if (!Chain.hasIncs()) | |||
2807 | return false; | |||
2808 | ||||
2809 | if (!Users.empty()) { | |||
2810 | LLVM_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) | |||
2811 | for (Instruction *Instdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Chain: " << *Chain. Incs[0].UserInst << " users:\n"; for (Instruction *Inst : Users) { dbgs() << " " << *Inst << "\n" ; }; } } while (false) | |||
2812 | : Users) { 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); | |||
2813 | return false; | |||
2814 | } | |||
2815 | assert(!Chain.Incs.empty() && "empty IV chains are not allowed")(static_cast <bool> (!Chain.Incs.empty() && "empty IV chains are not allowed" ) ? void (0) : __assert_fail ("!Chain.Incs.empty() && \"empty IV chains are not allowed\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 2815, __extension__ __PRETTY_FUNCTION__)); | |||
2816 | ||||
2817 | // The chain itself may require a register, so intialize cost to 1. | |||
2818 | int cost = 1; | |||
2819 | ||||
2820 | // A complete chain likely eliminates the need for keeping the original IV in | |||
2821 | // a register. LSR does not currently know how to form a complete chain unless | |||
2822 | // the header phi already exists. | |||
2823 | if (isa<PHINode>(Chain.tailUserInst()) | |||
2824 | && SE.getSCEV(Chain.tailUserInst()) == Chain.Incs[0].IncExpr) { | |||
2825 | --cost; | |||
2826 | } | |||
2827 | const SCEV *LastIncExpr = nullptr; | |||
2828 | unsigned NumConstIncrements = 0; | |||
2829 | unsigned NumVarIncrements = 0; | |||
2830 | unsigned NumReusedIncrements = 0; | |||
2831 | for (const IVInc &Inc : Chain) { | |||
2832 | if (Inc.IncExpr->isZero()) | |||
2833 | continue; | |||
2834 | ||||
2835 | // Incrementing by zero or some constant is neutral. We assume constants can | |||
2836 | // be folded into an addressing mode or an add's immediate operand. | |||
2837 | if (isa<SCEVConstant>(Inc.IncExpr)) { | |||
2838 | ++NumConstIncrements; | |||
2839 | continue; | |||
2840 | } | |||
2841 | ||||
2842 | if (Inc.IncExpr == LastIncExpr) | |||
2843 | ++NumReusedIncrements; | |||
2844 | else | |||
2845 | ++NumVarIncrements; | |||
2846 | ||||
2847 | LastIncExpr = Inc.IncExpr; | |||
2848 | } | |||
2849 | // An IV chain with a single increment is handled by LSR's postinc | |||
2850 | // uses. However, a chain with multiple increments requires keeping the IV's | |||
2851 | // value live longer than it needs to be if chained. | |||
2852 | if (NumConstIncrements > 1) | |||
2853 | --cost; | |||
2854 | ||||
2855 | // Materializing increment expressions in the preheader that didn't exist in | |||
2856 | // the original code may cost a register. For example, sign-extended array | |||
2857 | // indices can produce ridiculous increments like this: | |||
2858 | // IV + ((sext i32 (2 * %s) to i64) + (-1 * (sext i32 %s to i64))) | |||
2859 | cost += NumVarIncrements; | |||
2860 | ||||
2861 | // Reusing variable increments likely saves a register to hold the multiple of | |||
2862 | // the stride. | |||
2863 | cost -= NumReusedIncrements; | |||
2864 | ||||
2865 | LLVM_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) | |||
2866 | << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Chain: " << *Chain. Incs[0].UserInst << " Cost: " << cost << "\n" ; } } while (false); | |||
2867 | ||||
2868 | return cost < 0; | |||
2869 | } | |||
2870 | ||||
2871 | /// Add this IV user to an existing chain or make it the head of a new chain. | |||
2872 | void LSRInstance::ChainInstruction(Instruction *UserInst, Instruction *IVOper, | |||
2873 | SmallVectorImpl<ChainUsers> &ChainUsersVec) { | |||
2874 | // When IVs are used as types of varying widths, they are generally converted | |||
2875 | // to a wider type with some uses remaining narrow under a (free) trunc. | |||
2876 | Value *const NextIV = getWideOperand(IVOper); | |||
2877 | const SCEV *const OperExpr = SE.getSCEV(NextIV); | |||
2878 | const SCEV *const OperExprBase = getExprBase(OperExpr); | |||
2879 | ||||
2880 | // Visit all existing chains. Check if its IVOper can be computed as a | |||
2881 | // profitable loop invariant increment from the last link in the Chain. | |||
2882 | unsigned ChainIdx = 0, NChains = IVChainVec.size(); | |||
2883 | const SCEV *LastIncExpr = nullptr; | |||
2884 | for (; ChainIdx < NChains; ++ChainIdx) { | |||
2885 | IVChain &Chain = IVChainVec[ChainIdx]; | |||
2886 | ||||
2887 | // Prune the solution space aggressively by checking that both IV operands | |||
2888 | // are expressions that operate on the same unscaled SCEVUnknown. This | |||
2889 | // "base" will be canceled by the subsequent getMinusSCEV call. Checking | |||
2890 | // first avoids creating extra SCEV expressions. | |||
2891 | if (!StressIVChain && Chain.ExprBase != OperExprBase) | |||
2892 | continue; | |||
2893 | ||||
2894 | Value *PrevIV = getWideOperand(Chain.Incs.back().IVOperand); | |||
2895 | if (!isCompatibleIVType(PrevIV, NextIV)) | |||
2896 | continue; | |||
2897 | ||||
2898 | // A phi node terminates a chain. | |||
2899 | if (isa<PHINode>(UserInst) && isa<PHINode>(Chain.tailUserInst())) | |||
2900 | continue; | |||
2901 | ||||
2902 | // The increment must be loop-invariant so it can be kept in a register. | |||
2903 | const SCEV *PrevExpr = SE.getSCEV(PrevIV); | |||
2904 | const SCEV *IncExpr = SE.getMinusSCEV(OperExpr, PrevExpr); | |||
2905 | if (!SE.isLoopInvariant(IncExpr, L)) | |||
2906 | continue; | |||
2907 | ||||
2908 | if (Chain.isProfitableIncrement(OperExpr, IncExpr, SE)) { | |||
2909 | LastIncExpr = IncExpr; | |||
2910 | break; | |||
2911 | } | |||
2912 | } | |||
2913 | // If we haven't found a chain, create a new one, unless we hit the max. Don't | |||
2914 | // bother for phi nodes, because they must be last in the chain. | |||
2915 | if (ChainIdx == NChains) { | |||
2916 | if (isa<PHINode>(UserInst)) | |||
2917 | return; | |||
2918 | if (NChains >= MaxChains && !StressIVChain) { | |||
2919 | LLVM_DEBUG(dbgs() << "IV Chain Limit\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "IV Chain Limit\n"; } } while (false); | |||
2920 | return; | |||
2921 | } | |||
2922 | LastIncExpr = OperExpr; | |||
2923 | // IVUsers may have skipped over sign/zero extensions. We don't currently | |||
2924 | // attempt to form chains involving extensions unless they can be hoisted | |||
2925 | // into this loop's AddRec. | |||
2926 | if (!isa<SCEVAddRecExpr>(LastIncExpr)) | |||
2927 | return; | |||
2928 | ++NChains; | |||
2929 | IVChainVec.push_back(IVChain(IVInc(UserInst, IVOper, LastIncExpr), | |||
2930 | OperExprBase)); | |||
2931 | ChainUsersVec.resize(NChains); | |||
2932 | LLVM_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) | |||
2933 | << ") IV=" << *LastIncExpr << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx << " Head: (" << *UserInst << ") IV=" << *LastIncExpr << "\n"; } } while (false); | |||
2934 | } else { | |||
2935 | LLVM_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) | |||
2936 | << ") IV+" << *LastIncExpr << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx << " Inc: (" << *UserInst << ") IV+" << *LastIncExpr << "\n"; } } while (false); | |||
2937 | // Add this IV user to the end of the chain. | |||
2938 | IVChainVec[ChainIdx].add(IVInc(UserInst, IVOper, LastIncExpr)); | |||
2939 | } | |||
2940 | IVChain &Chain = IVChainVec[ChainIdx]; | |||
2941 | ||||
2942 | SmallPtrSet<Instruction*,4> &NearUsers = ChainUsersVec[ChainIdx].NearUsers; | |||
2943 | // This chain's NearUsers become FarUsers. | |||
2944 | if (!LastIncExpr->isZero()) { | |||
2945 | ChainUsersVec[ChainIdx].FarUsers.insert(NearUsers.begin(), | |||
2946 | NearUsers.end()); | |||
2947 | NearUsers.clear(); | |||
2948 | } | |||
2949 | ||||
2950 | // All other uses of IVOperand become near uses of the chain. | |||
2951 | // We currently ignore intermediate values within SCEV expressions, assuming | |||
2952 | // they will eventually be used be the current chain, or can be computed | |||
2953 | // from one of the chain increments. To be more precise we could | |||
2954 | // transitively follow its user and only add leaf IV users to the set. | |||
2955 | for (User *U : IVOper->users()) { | |||
2956 | Instruction *OtherUse = dyn_cast<Instruction>(U); | |||
2957 | if (!OtherUse) | |||
2958 | continue; | |||
2959 | // Uses in the chain will no longer be uses if the chain is formed. | |||
2960 | // Include the head of the chain in this iteration (not Chain.begin()). | |||
2961 | IVChain::const_iterator IncIter = Chain.Incs.begin(); | |||
2962 | IVChain::const_iterator IncEnd = Chain.Incs.end(); | |||
2963 | for( ; IncIter != IncEnd; ++IncIter) { | |||
2964 | if (IncIter->UserInst == OtherUse) | |||
2965 | break; | |||
2966 | } | |||
2967 | if (IncIter != IncEnd) | |||
2968 | continue; | |||
2969 | ||||
2970 | if (SE.isSCEVable(OtherUse->getType()) | |||
2971 | && !isa<SCEVUnknown>(SE.getSCEV(OtherUse)) | |||
2972 | && IU.isIVUserOrOperand(OtherUse)) { | |||
2973 | continue; | |||
2974 | } | |||
2975 | NearUsers.insert(OtherUse); | |||
2976 | } | |||
2977 | ||||
2978 | // Since this user is part of the chain, it's no longer considered a use | |||
2979 | // of the chain. | |||
2980 | ChainUsersVec[ChainIdx].FarUsers.erase(UserInst); | |||
2981 | } | |||
2982 | ||||
2983 | /// Populate the vector of Chains. | |||
2984 | /// | |||
2985 | /// This decreases ILP at the architecture level. Targets with ample registers, | |||
2986 | /// multiple memory ports, and no register renaming probably don't want | |||
2987 | /// this. However, such targets should probably disable LSR altogether. | |||
2988 | /// | |||
2989 | /// The job of LSR is to make a reasonable choice of induction variables across | |||
2990 | /// the loop. Subsequent passes can easily "unchain" computation exposing more | |||
2991 | /// ILP *within the loop* if the target wants it. | |||
2992 | /// | |||
2993 | /// Finding the best IV chain is potentially a scheduling problem. Since LSR | |||
2994 | /// will not reorder memory operations, it will recognize this as a chain, but | |||
2995 | /// will generate redundant IV increments. Ideally this would be corrected later | |||
2996 | /// by a smart scheduler: | |||
2997 | /// = A[i] | |||
2998 | /// = A[i+x] | |||
2999 | /// A[i] = | |||
3000 | /// A[i+x] = | |||
3001 | /// | |||
3002 | /// TODO: Walk the entire domtree within this loop, not just the path to the | |||
3003 | /// loop latch. This will discover chains on side paths, but requires | |||
3004 | /// maintaining multiple copies of the Chains state. | |||
3005 | void LSRInstance::CollectChains() { | |||
3006 | LLVM_DEBUG(dbgs() << "Collecting IV Chains.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Collecting IV Chains.\n"; } } while (false); | |||
3007 | SmallVector<ChainUsers, 8> ChainUsersVec; | |||
3008 | ||||
3009 | SmallVector<BasicBlock *,8> LatchPath; | |||
3010 | BasicBlock *LoopHeader = L->getHeader(); | |||
3011 | for (DomTreeNode *Rung = DT.getNode(L->getLoopLatch()); | |||
3012 | Rung->getBlock() != LoopHeader; Rung = Rung->getIDom()) { | |||
3013 | LatchPath.push_back(Rung->getBlock()); | |||
3014 | } | |||
3015 | LatchPath.push_back(LoopHeader); | |||
3016 | ||||
3017 | // Walk the instruction stream from the loop header to the loop latch. | |||
3018 | for (BasicBlock *BB : reverse(LatchPath)) { | |||
3019 | for (Instruction &I : *BB) { | |||
3020 | // Skip instructions that weren't seen by IVUsers analysis. | |||
3021 | if (isa<PHINode>(I) || !IU.isIVUserOrOperand(&I)) | |||
3022 | continue; | |||
3023 | ||||
3024 | // Ignore users that are part of a SCEV expression. This way we only | |||
3025 | // consider leaf IV Users. This effectively rediscovers a portion of | |||
3026 | // IVUsers analysis but in program order this time. | |||
3027 | if (SE.isSCEVable(I.getType()) && !isa<SCEVUnknown>(SE.getSCEV(&I))) | |||
3028 | continue; | |||
3029 | ||||
3030 | // Remove this instruction from any NearUsers set it may be in. | |||
3031 | for (unsigned ChainIdx = 0, NChains = IVChainVec.size(); | |||
3032 | ChainIdx < NChains; ++ChainIdx) { | |||
3033 | ChainUsersVec[ChainIdx].NearUsers.erase(&I); | |||
3034 | } | |||
3035 | // Search for operands that can be chained. | |||
3036 | SmallPtrSet<Instruction*, 4> UniqueOperands; | |||
3037 | User::op_iterator IVOpEnd = I.op_end(); | |||
3038 | User::op_iterator IVOpIter = findIVOperand(I.op_begin(), IVOpEnd, L, SE); | |||
3039 | while (IVOpIter != IVOpEnd) { | |||
3040 | Instruction *IVOpInst = cast<Instruction>(*IVOpIter); | |||
3041 | if (UniqueOperands.insert(IVOpInst).second) | |||
3042 | ChainInstruction(&I, IVOpInst, ChainUsersVec); | |||
3043 | IVOpIter = findIVOperand(std::next(IVOpIter), IVOpEnd, L, SE); | |||
3044 | } | |||
3045 | } // Continue walking down the instructions. | |||
3046 | } // Continue walking down the domtree. | |||
3047 | // Visit phi backedges to determine if the chain can generate the IV postinc. | |||
3048 | for (PHINode &PN : L->getHeader()->phis()) { | |||
3049 | if (!SE.isSCEVable(PN.getType())) | |||
3050 | continue; | |||
3051 | ||||
3052 | Instruction *IncV = | |||
3053 | dyn_cast<Instruction>(PN.getIncomingValueForBlock(L->getLoopLatch())); | |||
3054 | if (IncV) | |||
3055 | ChainInstruction(&PN, IncV, ChainUsersVec); | |||
3056 | } | |||
3057 | // Remove any unprofitable chains. | |||
3058 | unsigned ChainIdx = 0; | |||
3059 | for (unsigned UsersIdx = 0, NChains = IVChainVec.size(); | |||
3060 | UsersIdx < NChains; ++UsersIdx) { | |||
3061 | if (!isProfitableChain(IVChainVec[UsersIdx], | |||
3062 | ChainUsersVec[UsersIdx].FarUsers, SE, TTI)) | |||
3063 | continue; | |||
3064 | // Preserve the chain at UsesIdx. | |||
3065 | if (ChainIdx != UsersIdx) | |||
3066 | IVChainVec[ChainIdx] = IVChainVec[UsersIdx]; | |||
3067 | FinalizeChain(IVChainVec[ChainIdx]); | |||
3068 | ++ChainIdx; | |||
3069 | } | |||
3070 | IVChainVec.resize(ChainIdx); | |||
3071 | } | |||
3072 | ||||
3073 | void LSRInstance::FinalizeChain(IVChain &Chain) { | |||
3074 | assert(!Chain.Incs.empty() && "empty IV chains are not allowed")(static_cast <bool> (!Chain.Incs.empty() && "empty IV chains are not allowed" ) ? void (0) : __assert_fail ("!Chain.Incs.empty() && \"empty IV chains are not allowed\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3074, __extension__ __PRETTY_FUNCTION__)); | |||
3075 | LLVM_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); | |||
3076 | ||||
3077 | for (const IVInc &Inc : Chain) { | |||
3078 | LLVM_DEBUG(dbgs() << " Inc: " << *Inc.UserInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Inc: " << * Inc.UserInst << "\n"; } } while (false); | |||
3079 | auto UseI = find(Inc.UserInst->operands(), Inc.IVOperand); | |||
3080 | assert(UseI != Inc.UserInst->op_end() && "cannot find IV operand")(static_cast <bool> (UseI != Inc.UserInst->op_end() && "cannot find IV operand") ? void (0) : __assert_fail ("UseI != Inc.UserInst->op_end() && \"cannot find IV operand\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3080, __extension__ __PRETTY_FUNCTION__)); | |||
3081 | IVIncSet.insert(UseI); | |||
3082 | } | |||
3083 | } | |||
3084 | ||||
3085 | /// Return true if the IVInc can be folded into an addressing mode. | |||
3086 | static bool canFoldIVIncExpr(const SCEV *IncExpr, Instruction *UserInst, | |||
3087 | Value *Operand, const TargetTransformInfo &TTI) { | |||
3088 | const SCEVConstant *IncConst = dyn_cast<SCEVConstant>(IncExpr); | |||
3089 | if (!IncConst || !isAddressUse(TTI, UserInst, Operand)) | |||
3090 | return false; | |||
3091 | ||||
3092 | if (IncConst->getAPInt().getMinSignedBits() > 64) | |||
3093 | return false; | |||
3094 | ||||
3095 | MemAccessTy AccessTy = getAccessType(TTI, UserInst, Operand); | |||
3096 | int64_t IncOffset = IncConst->getValue()->getSExtValue(); | |||
3097 | if (!isAlwaysFoldable(TTI, LSRUse::Address, AccessTy, /*BaseGV=*/nullptr, | |||
3098 | IncOffset, /*HaseBaseReg=*/false)) | |||
3099 | return false; | |||
3100 | ||||
3101 | return true; | |||
3102 | } | |||
3103 | ||||
3104 | /// Generate an add or subtract for each IVInc in a chain to materialize the IV | |||
3105 | /// user's operand from the previous IV user's operand. | |||
3106 | void LSRInstance::GenerateIVChain(const IVChain &Chain, SCEVExpander &Rewriter, | |||
3107 | SmallVectorImpl<WeakTrackingVH> &DeadInsts) { | |||
3108 | // Find the new IVOperand for the head of the chain. It may have been replaced | |||
3109 | // by LSR. | |||
3110 | const IVInc &Head = Chain.Incs[0]; | |||
3111 | User::op_iterator IVOpEnd = Head.UserInst->op_end(); | |||
3112 | // findIVOperand returns IVOpEnd if it can no longer find a valid IV user. | |||
3113 | User::op_iterator IVOpIter = findIVOperand(Head.UserInst->op_begin(), | |||
3114 | IVOpEnd, L, SE); | |||
3115 | Value *IVSrc = nullptr; | |||
3116 | while (IVOpIter != IVOpEnd) { | |||
3117 | IVSrc = getWideOperand(*IVOpIter); | |||
3118 | ||||
3119 | // If this operand computes the expression that the chain needs, we may use | |||
3120 | // it. (Check this after setting IVSrc which is used below.) | |||
3121 | // | |||
3122 | // Note that if Head.IncExpr is wider than IVSrc, then this phi is too | |||
3123 | // narrow for the chain, so we can no longer use it. We do allow using a | |||
3124 | // wider phi, assuming the LSR checked for free truncation. In that case we | |||
3125 | // should already have a truncate on this operand such that | |||
3126 | // getSCEV(IVSrc) == IncExpr. | |||
3127 | if (SE.getSCEV(*IVOpIter) == Head.IncExpr | |||
3128 | || SE.getSCEV(IVSrc) == Head.IncExpr) { | |||
3129 | break; | |||
3130 | } | |||
3131 | IVOpIter = findIVOperand(std::next(IVOpIter), IVOpEnd, L, SE); | |||
3132 | } | |||
3133 | if (IVOpIter == IVOpEnd) { | |||
3134 | // Gracefully give up on this chain. | |||
3135 | LLVM_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); | |||
3136 | return; | |||
3137 | } | |||
3138 | ||||
3139 | LLVM_DEBUG(dbgs() << "Generate chain at: " << *IVSrc << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Generate chain at: " << *IVSrc << "\n"; } } while (false); | |||
3140 | Type *IVTy = IVSrc->getType(); | |||
3141 | Type *IntTy = SE.getEffectiveSCEVType(IVTy); | |||
3142 | const SCEV *LeftOverExpr = nullptr; | |||
3143 | for (const IVInc &Inc : Chain) { | |||
3144 | Instruction *InsertPt = Inc.UserInst; | |||
3145 | if (isa<PHINode>(InsertPt)) | |||
3146 | InsertPt = L->getLoopLatch()->getTerminator(); | |||
3147 | ||||
3148 | // IVOper will replace the current IV User's operand. IVSrc is the IV | |||
3149 | // value currently held in a register. | |||
3150 | Value *IVOper = IVSrc; | |||
3151 | if (!Inc.IncExpr->isZero()) { | |||
3152 | // IncExpr was the result of subtraction of two narrow values, so must | |||
3153 | // be signed. | |||
3154 | const SCEV *IncExpr = SE.getNoopOrSignExtend(Inc.IncExpr, IntTy); | |||
3155 | LeftOverExpr = LeftOverExpr ? | |||
3156 | SE.getAddExpr(LeftOverExpr, IncExpr) : IncExpr; | |||
3157 | } | |||
3158 | if (LeftOverExpr && !LeftOverExpr->isZero()) { | |||
3159 | // Expand the IV increment. | |||
3160 | Rewriter.clearPostInc(); | |||
3161 | Value *IncV = Rewriter.expandCodeFor(LeftOverExpr, IntTy, InsertPt); | |||
3162 | const SCEV *IVOperExpr = SE.getAddExpr(SE.getUnknown(IVSrc), | |||
3163 | SE.getUnknown(IncV)); | |||
3164 | IVOper = Rewriter.expandCodeFor(IVOperExpr, IVTy, InsertPt); | |||
3165 | ||||
3166 | // If an IV increment can't be folded, use it as the next IV value. | |||
3167 | if (!canFoldIVIncExpr(LeftOverExpr, Inc.UserInst, Inc.IVOperand, TTI)) { | |||
3168 | assert(IVTy == IVOper->getType() && "inconsistent IV increment type")(static_cast <bool> (IVTy == IVOper->getType() && "inconsistent IV increment type") ? void (0) : __assert_fail ("IVTy == IVOper->getType() && \"inconsistent IV increment type\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3168, __extension__ __PRETTY_FUNCTION__)); | |||
3169 | IVSrc = IVOper; | |||
3170 | LeftOverExpr = nullptr; | |||
3171 | } | |||
3172 | } | |||
3173 | Type *OperTy = Inc.IVOperand->getType(); | |||
3174 | if (IVTy != OperTy) { | |||
3175 | assert(SE.getTypeSizeInBits(IVTy) >= SE.getTypeSizeInBits(OperTy) &&(static_cast <bool> (SE.getTypeSizeInBits(IVTy) >= SE .getTypeSizeInBits(OperTy) && "cannot extend a chained IV" ) ? void (0) : __assert_fail ("SE.getTypeSizeInBits(IVTy) >= SE.getTypeSizeInBits(OperTy) && \"cannot extend a chained IV\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3176, __extension__ __PRETTY_FUNCTION__)) | |||
3176 | "cannot extend a chained IV")(static_cast <bool> (SE.getTypeSizeInBits(IVTy) >= SE .getTypeSizeInBits(OperTy) && "cannot extend a chained IV" ) ? void (0) : __assert_fail ("SE.getTypeSizeInBits(IVTy) >= SE.getTypeSizeInBits(OperTy) && \"cannot extend a chained IV\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3176, __extension__ __PRETTY_FUNCTION__)); | |||
3177 | IRBuilder<> Builder(InsertPt); | |||
3178 | IVOper = Builder.CreateTruncOrBitCast(IVOper, OperTy, "lsr.chain"); | |||
3179 | } | |||
3180 | Inc.UserInst->replaceUsesOfWith(Inc.IVOperand, IVOper); | |||
3181 | DeadInsts.emplace_back(Inc.IVOperand); | |||
3182 | } | |||
3183 | // If LSR created a new, wider phi, we may also replace its postinc. We only | |||
3184 | // do this if we also found a wide value for the head of the chain. | |||
3185 | if (isa<PHINode>(Chain.tailUserInst())) { | |||
3186 | for (PHINode &Phi : L->getHeader()->phis()) { | |||
3187 | if (!isCompatibleIVType(&Phi, IVSrc)) | |||
3188 | continue; | |||
3189 | Instruction *PostIncV = dyn_cast<Instruction>( | |||
3190 | Phi.getIncomingValueForBlock(L->getLoopLatch())); | |||
3191 | if (!PostIncV || (SE.getSCEV(PostIncV) != SE.getSCEV(IVSrc))) | |||
3192 | continue; | |||
3193 | Value *IVOper = IVSrc; | |||
3194 | Type *PostIncTy = PostIncV->getType(); | |||
3195 | if (IVTy != PostIncTy) { | |||
3196 | assert(PostIncTy->isPointerTy() && "mixing int/ptr IV types")(static_cast <bool> (PostIncTy->isPointerTy() && "mixing int/ptr IV types") ? void (0) : __assert_fail ("PostIncTy->isPointerTy() && \"mixing int/ptr IV types\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3196, __extension__ __PRETTY_FUNCTION__)); | |||
3197 | IRBuilder<> Builder(L->getLoopLatch()->getTerminator()); | |||
3198 | Builder.SetCurrentDebugLocation(PostIncV->getDebugLoc()); | |||
3199 | IVOper = Builder.CreatePointerCast(IVSrc, PostIncTy, "lsr.chain"); | |||
3200 | } | |||
3201 | Phi.replaceUsesOfWith(PostIncV, IVOper); | |||
3202 | DeadInsts.emplace_back(PostIncV); | |||
3203 | } | |||
3204 | } | |||
3205 | } | |||
3206 | ||||
3207 | void LSRInstance::CollectFixupsAndInitialFormulae() { | |||
3208 | for (const IVStrideUse &U : IU) { | |||
3209 | Instruction *UserInst = U.getUser(); | |||
3210 | // Skip IV users that are part of profitable IV Chains. | |||
3211 | User::op_iterator UseI = | |||
3212 | find(UserInst->operands(), U.getOperandValToReplace()); | |||
3213 | assert(UseI != UserInst->op_end() && "cannot find IV operand")(static_cast <bool> (UseI != UserInst->op_end() && "cannot find IV operand") ? void (0) : __assert_fail ("UseI != UserInst->op_end() && \"cannot find IV operand\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3213, __extension__ __PRETTY_FUNCTION__)); | |||
3214 | if (IVIncSet.count(UseI)) { | |||
3215 | LLVM_DEBUG(dbgs() << "Use is in profitable chain: " << **UseI << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Use is in profitable chain: " << **UseI << '\n'; } } while (false); | |||
3216 | continue; | |||
3217 | } | |||
3218 | ||||
3219 | LSRUse::KindType Kind = LSRUse::Basic; | |||
3220 | MemAccessTy AccessTy; | |||
3221 | if (isAddressUse(TTI, UserInst, U.getOperandValToReplace())) { | |||
3222 | Kind = LSRUse::Address; | |||
3223 | AccessTy = getAccessType(TTI, UserInst, U.getOperandValToReplace()); | |||
3224 | } | |||
3225 | ||||
3226 | const SCEV *S = IU.getExpr(U); | |||
3227 | PostIncLoopSet TmpPostIncLoops = U.getPostIncLoops(); | |||
3228 | ||||
3229 | // Equality (== and !=) ICmps are special. We can rewrite (i == N) as | |||
3230 | // (N - i == 0), and this allows (N - i) to be the expression that we work | |||
3231 | // with rather than just N or i, so we can consider the register | |||
3232 | // requirements for both N and i at the same time. Limiting this code to | |||
3233 | // equality icmps is not a problem because all interesting loops use | |||
3234 | // equality icmps, thanks to IndVarSimplify. | |||
3235 | if (ICmpInst *CI = dyn_cast<ICmpInst>(UserInst)) | |||
3236 | if (CI->isEquality()) { | |||
3237 | // Swap the operands if needed to put the OperandValToReplace on the | |||
3238 | // left, for consistency. | |||
3239 | Value *NV = CI->getOperand(1); | |||
3240 | if (NV == U.getOperandValToReplace()) { | |||
3241 | CI->setOperand(1, CI->getOperand(0)); | |||
3242 | CI->setOperand(0, NV); | |||
3243 | NV = CI->getOperand(1); | |||
3244 | Changed = true; | |||
3245 | } | |||
3246 | ||||
3247 | // x == y --> x - y == 0 | |||
3248 | const SCEV *N = SE.getSCEV(NV); | |||
3249 | if (SE.isLoopInvariant(N, L) && isSafeToExpand(N, SE)) { | |||
3250 | // S is normalized, so normalize N before folding it into S | |||
3251 | // to keep the result normalized. | |||
3252 | N = normalizeForPostIncUse(N, TmpPostIncLoops, SE); | |||
3253 | Kind = LSRUse::ICmpZero; | |||
3254 | S = SE.getMinusSCEV(N, S); | |||
3255 | } | |||
3256 | ||||
3257 | // -1 and the negations of all interesting strides (except the negation | |||
3258 | // of -1) are now also interesting. | |||
3259 | for (size_t i = 0, e = Factors.size(); i != e; ++i) | |||
3260 | if (Factors[i] != -1) | |||
3261 | Factors.insert(-(uint64_t)Factors[i]); | |||
3262 | Factors.insert(-1); | |||
3263 | } | |||
3264 | ||||
3265 | // Get or create an LSRUse. | |||
3266 | std::pair<size_t, int64_t> P = getUse(S, Kind, AccessTy); | |||
3267 | size_t LUIdx = P.first; | |||
3268 | int64_t Offset = P.second; | |||
3269 | LSRUse &LU = Uses[LUIdx]; | |||
3270 | ||||
3271 | // Record the fixup. | |||
3272 | LSRFixup &LF = LU.getNewFixup(); | |||
3273 | LF.UserInst = UserInst; | |||
3274 | LF.OperandValToReplace = U.getOperandValToReplace(); | |||
3275 | LF.PostIncLoops = TmpPostIncLoops; | |||
3276 | LF.Offset = Offset; | |||
3277 | LU.AllFixupsOutsideLoop &= LF.isUseFullyOutsideLoop(L); | |||
3278 | ||||
3279 | if (!LU.WidestFixupType || | |||
3280 | SE.getTypeSizeInBits(LU.WidestFixupType) < | |||
3281 | SE.getTypeSizeInBits(LF.OperandValToReplace->getType())) | |||
3282 | LU.WidestFixupType = LF.OperandValToReplace->getType(); | |||
3283 | ||||
3284 | // If this is the first use of this LSRUse, give it a formula. | |||
3285 | if (LU.Formulae.empty()) { | |||
3286 | InsertInitialFormula(S, LU, LUIdx); | |||
3287 | CountRegisters(LU.Formulae.back(), LUIdx); | |||
3288 | } | |||
3289 | } | |||
3290 | ||||
3291 | LLVM_DEBUG(print_fixups(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { print_fixups(dbgs()); } } while (false); | |||
3292 | } | |||
3293 | ||||
3294 | /// Insert a formula for the given expression into the given use, separating out | |||
3295 | /// loop-variant portions from loop-invariant and loop-computable portions. | |||
3296 | void | |||
3297 | LSRInstance::InsertInitialFormula(const SCEV *S, LSRUse &LU, size_t LUIdx) { | |||
3298 | // Mark uses whose expressions cannot be expanded. | |||
3299 | if (!isSafeToExpand(S, SE)) | |||
3300 | LU.RigidFormula = true; | |||
3301 | ||||
3302 | Formula F; | |||
3303 | F.initialMatch(S, L, SE); | |||
3304 | bool Inserted = InsertFormula(LU, LUIdx, F); | |||
3305 | assert(Inserted && "Initial formula already exists!")(static_cast <bool> (Inserted && "Initial formula already exists!" ) ? void (0) : __assert_fail ("Inserted && \"Initial formula already exists!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3305, __extension__ __PRETTY_FUNCTION__)); (void)Inserted; | |||
3306 | } | |||
3307 | ||||
3308 | /// Insert a simple single-register formula for the given expression into the | |||
3309 | /// given use. | |||
3310 | void | |||
3311 | LSRInstance::InsertSupplementalFormula(const SCEV *S, | |||
3312 | LSRUse &LU, size_t LUIdx) { | |||
3313 | Formula F; | |||
3314 | F.BaseRegs.push_back(S); | |||
3315 | F.HasBaseReg = true; | |||
3316 | bool Inserted = InsertFormula(LU, LUIdx, F); | |||
3317 | assert(Inserted && "Supplemental formula already exists!")(static_cast <bool> (Inserted && "Supplemental formula already exists!" ) ? void (0) : __assert_fail ("Inserted && \"Supplemental formula already exists!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3317, __extension__ __PRETTY_FUNCTION__)); (void)Inserted; | |||
3318 | } | |||
3319 | ||||
3320 | /// Note which registers are used by the given formula, updating RegUses. | |||
3321 | void LSRInstance::CountRegisters(const Formula &F, size_t LUIdx) { | |||
3322 | if (F.ScaledReg) | |||
3323 | RegUses.countRegister(F.ScaledReg, LUIdx); | |||
3324 | for (const SCEV *BaseReg : F.BaseRegs) | |||
3325 | RegUses.countRegister(BaseReg, LUIdx); | |||
3326 | } | |||
3327 | ||||
3328 | /// If the given formula has not yet been inserted, add it to the list, and | |||
3329 | /// return true. Return false otherwise. | |||
3330 | bool LSRInstance::InsertFormula(LSRUse &LU, unsigned LUIdx, const Formula &F) { | |||
3331 | // Do not insert formula that we will not be able to expand. | |||
3332 | assert(isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) &&(static_cast <bool> (isLegalUse(TTI, LU.MinOffset, LU.MaxOffset , LU.Kind, LU.AccessTy, F) && "Formula is illegal") ? void (0) : __assert_fail ("isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) && \"Formula is illegal\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3333, __extension__ __PRETTY_FUNCTION__)) | |||
3333 | "Formula is illegal")(static_cast <bool> (isLegalUse(TTI, LU.MinOffset, LU.MaxOffset , LU.Kind, LU.AccessTy, F) && "Formula is illegal") ? void (0) : __assert_fail ("isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) && \"Formula is illegal\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3333, __extension__ __PRETTY_FUNCTION__)); | |||
3334 | ||||
3335 | if (!LU.InsertFormula(F, *L)) | |||
3336 | return false; | |||
3337 | ||||
3338 | CountRegisters(F, LUIdx); | |||
3339 | return true; | |||
3340 | } | |||
3341 | ||||
3342 | /// Check for other uses of loop-invariant values which we're tracking. These | |||
3343 | /// other uses will pin these values in registers, making them less profitable | |||
3344 | /// for elimination. | |||
3345 | /// TODO: This currently misses non-constant addrec step registers. | |||
3346 | /// TODO: Should this give more weight to users inside the loop? | |||
3347 | void | |||
3348 | LSRInstance::CollectLoopInvariantFixupsAndFormulae() { | |||
3349 | SmallVector<const SCEV *, 8> Worklist(RegUses.begin(), RegUses.end()); | |||
3350 | SmallPtrSet<const SCEV *, 32> Visited; | |||
3351 | ||||
3352 | while (!Worklist.empty()) { | |||
3353 | const SCEV *S = Worklist.pop_back_val(); | |||
3354 | ||||
3355 | // Don't process the same SCEV twice | |||
3356 | if (!Visited.insert(S).second) | |||
3357 | continue; | |||
3358 | ||||
3359 | if (const SCEVNAryExpr *N = dyn_cast<SCEVNAryExpr>(S)) | |||
3360 | Worklist.append(N->op_begin(), N->op_end()); | |||
3361 | else if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(S)) | |||
3362 | Worklist.push_back(C->getOperand()); | |||
3363 | else if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) { | |||
3364 | Worklist.push_back(D->getLHS()); | |||
3365 | Worklist.push_back(D->getRHS()); | |||
3366 | } else if (const SCEVUnknown *US = dyn_cast<SCEVUnknown>(S)) { | |||
3367 | const Value *V = US->getValue(); | |||
3368 | if (const Instruction *Inst = dyn_cast<Instruction>(V)) { | |||
3369 | // Look for instructions defined outside the loop. | |||
3370 | if (L->contains(Inst)) continue; | |||
3371 | } else if (isa<UndefValue>(V)) | |||
3372 | // Undef doesn't have a live range, so it doesn't matter. | |||
3373 | continue; | |||
3374 | for (const Use &U : V->uses()) { | |||
3375 | const Instruction *UserInst = dyn_cast<Instruction>(U.getUser()); | |||
3376 | // Ignore non-instructions. | |||
3377 | if (!UserInst) | |||
3378 | continue; | |||
3379 | // Ignore instructions in other functions (as can happen with | |||
3380 | // Constants). | |||
3381 | if (UserInst->getParent()->getParent() != L->getHeader()->getParent()) | |||
3382 | continue; | |||
3383 | // Ignore instructions not dominated by the loop. | |||
3384 | const BasicBlock *UseBB = !isa<PHINode>(UserInst) ? | |||
3385 | UserInst->getParent() : | |||
3386 | cast<PHINode>(UserInst)->getIncomingBlock( | |||
3387 | PHINode::getIncomingValueNumForOperand(U.getOperandNo())); | |||
3388 | if (!DT.dominates(L->getHeader(), UseBB)) | |||
3389 | continue; | |||
3390 | // Don't bother if the instruction is in a BB which ends in an EHPad. | |||
3391 | if (UseBB->getTerminator()->isEHPad()) | |||
3392 | continue; | |||
3393 | // Don't bother rewriting PHIs in catchswitch blocks. | |||
3394 | if (isa<CatchSwitchInst>(UserInst->getParent()->getTerminator())) | |||
3395 | continue; | |||
3396 | // Ignore uses which are part of other SCEV expressions, to avoid | |||
3397 | // analyzing them multiple times. | |||
3398 | if (SE.isSCEVable(UserInst->getType())) { | |||
3399 | const SCEV *UserS = SE.getSCEV(const_cast<Instruction *>(UserInst)); | |||
3400 | // If the user is a no-op, look through to its uses. | |||
3401 | if (!isa<SCEVUnknown>(UserS)) | |||
3402 | continue; | |||
3403 | if (UserS == US) { | |||
3404 | Worklist.push_back( | |||
3405 | SE.getUnknown(const_cast<Instruction *>(UserInst))); | |||
3406 | continue; | |||
3407 | } | |||
3408 | } | |||
3409 | // Ignore icmp instructions which are already being analyzed. | |||
3410 | if (const ICmpInst *ICI = dyn_cast<ICmpInst>(UserInst)) { | |||
3411 | unsigned OtherIdx = !U.getOperandNo(); | |||
3412 | Value *OtherOp = const_cast<Value *>(ICI->getOperand(OtherIdx)); | |||
3413 | if (SE.hasComputableLoopEvolution(SE.getSCEV(OtherOp), L)) | |||
3414 | continue; | |||
3415 | } | |||
3416 | ||||
3417 | std::pair<size_t, int64_t> P = getUse( | |||
3418 | S, LSRUse::Basic, MemAccessTy()); | |||
3419 | size_t LUIdx = P.first; | |||
3420 | int64_t Offset = P.second; | |||
3421 | LSRUse &LU = Uses[LUIdx]; | |||
3422 | LSRFixup &LF = LU.getNewFixup(); | |||
3423 | LF.UserInst = const_cast<Instruction *>(UserInst); | |||
3424 | LF.OperandValToReplace = U; | |||
3425 | LF.Offset = Offset; | |||
3426 | LU.AllFixupsOutsideLoop &= LF.isUseFullyOutsideLoop(L); | |||
3427 | if (!LU.WidestFixupType || | |||
3428 | SE.getTypeSizeInBits(LU.WidestFixupType) < | |||
3429 | SE.getTypeSizeInBits(LF.OperandValToReplace->getType())) | |||
3430 | LU.WidestFixupType = LF.OperandValToReplace->getType(); | |||
3431 | InsertSupplementalFormula(US, LU, LUIdx); | |||
3432 | CountRegisters(LU.Formulae.back(), Uses.size() - 1); | |||
3433 | break; | |||
3434 | } | |||
3435 | } | |||
3436 | } | |||
3437 | } | |||
3438 | ||||
3439 | /// Split S into subexpressions which can be pulled out into separate | |||
3440 | /// registers. If C is non-null, multiply each subexpression by C. | |||
3441 | /// | |||
3442 | /// Return remainder expression after factoring the subexpressions captured by | |||
3443 | /// Ops. If Ops is complete, return NULL. | |||
3444 | static const SCEV *CollectSubexprs(const SCEV *S, const SCEVConstant *C, | |||
3445 | SmallVectorImpl<const SCEV *> &Ops, | |||
3446 | const Loop *L, | |||
3447 | ScalarEvolution &SE, | |||
3448 | unsigned Depth = 0) { | |||
3449 | // Arbitrarily cap recursion to protect compile time. | |||
3450 | if (Depth >= 3) | |||
3451 | return S; | |||
3452 | ||||
3453 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) { | |||
3454 | // Break out add operands. | |||
3455 | for (const SCEV *S : Add->operands()) { | |||
3456 | const SCEV *Remainder = CollectSubexprs(S, C, Ops, L, SE, Depth+1); | |||
3457 | if (Remainder) | |||
3458 | Ops.push_back(C ? SE.getMulExpr(C, Remainder) : Remainder); | |||
3459 | } | |||
3460 | return nullptr; | |||
3461 | } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) { | |||
3462 | // Split a non-zero base out of an addrec. | |||
3463 | if (AR->getStart()->isZero() || !AR->isAffine()) | |||
3464 | return S; | |||
3465 | ||||
3466 | const SCEV *Remainder = CollectSubexprs(AR->getStart(), | |||
3467 | C, Ops, L, SE, Depth+1); | |||
3468 | // Split the non-zero AddRec unless it is part of a nested recurrence that | |||
3469 | // does not pertain to this loop. | |||
3470 | if (Remainder && (AR->getLoop() == L || !isa<SCEVAddRecExpr>(Remainder))) { | |||
3471 | Ops.push_back(C ? SE.getMulExpr(C, Remainder) : Remainder); | |||
3472 | Remainder = nullptr; | |||
3473 | } | |||
3474 | if (Remainder != AR->getStart()) { | |||
3475 | if (!Remainder) | |||
3476 | Remainder = SE.getConstant(AR->getType(), 0); | |||
3477 | return SE.getAddRecExpr(Remainder, | |||
3478 | AR->getStepRecurrence(SE), | |||
3479 | AR->getLoop(), | |||
3480 | //FIXME: AR->getNoWrapFlags(SCEV::FlagNW) | |||
3481 | SCEV::FlagAnyWrap); | |||
3482 | } | |||
3483 | } else if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) { | |||
3484 | // Break (C * (a + b + c)) into C*a + C*b + C*c. | |||
3485 | if (Mul->getNumOperands() != 2) | |||
3486 | return S; | |||
3487 | if (const SCEVConstant *Op0 = | |||
3488 | dyn_cast<SCEVConstant>(Mul->getOperand(0))) { | |||
3489 | C = C ? cast<SCEVConstant>(SE.getMulExpr(C, Op0)) : Op0; | |||
3490 | const SCEV *Remainder = | |||
3491 | CollectSubexprs(Mul->getOperand(1), C, Ops, L, SE, Depth+1); | |||
3492 | if (Remainder) | |||
3493 | Ops.push_back(SE.getMulExpr(C, Remainder)); | |||
3494 | return nullptr; | |||
3495 | } | |||
3496 | } | |||
3497 | return S; | |||
3498 | } | |||
3499 | ||||
3500 | /// Return true if the SCEV represents a value that may end up as a | |||
3501 | /// post-increment operation. | |||
3502 | static bool mayUsePostIncMode(const TargetTransformInfo &TTI, | |||
3503 | LSRUse &LU, const SCEV *S, const Loop *L, | |||
3504 | ScalarEvolution &SE) { | |||
3505 | if (LU.Kind != LSRUse::Address || | |||
3506 | !LU.AccessTy.getType()->isIntOrIntVectorTy()) | |||
3507 | return false; | |||
3508 | const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S); | |||
3509 | if (!AR) | |||
3510 | return false; | |||
3511 | const SCEV *LoopStep = AR->getStepRecurrence(SE); | |||
3512 | if (!isa<SCEVConstant>(LoopStep)) | |||
3513 | return false; | |||
3514 | if (LU.AccessTy.getType()->getScalarSizeInBits() != | |||
3515 | LoopStep->getType()->getScalarSizeInBits()) | |||
3516 | return false; | |||
3517 | // Check if a post-indexed load/store can be used. | |||
3518 | if (TTI.isIndexedLoadLegal(TTI.MIM_PostInc, AR->getType()) || | |||
3519 | TTI.isIndexedStoreLegal(TTI.MIM_PostInc, AR->getType())) { | |||
3520 | const SCEV *LoopStart = AR->getStart(); | |||
3521 | if (!isa<SCEVConstant>(LoopStart) && SE.isLoopInvariant(LoopStart, L)) | |||
3522 | return true; | |||
3523 | } | |||
3524 | return false; | |||
3525 | } | |||
3526 | ||||
3527 | /// Helper function for LSRInstance::GenerateReassociations. | |||
3528 | void LSRInstance::GenerateReassociationsImpl(LSRUse &LU, unsigned LUIdx, | |||
3529 | const Formula &Base, | |||
3530 | unsigned Depth, size_t Idx, | |||
3531 | bool IsScaledReg) { | |||
3532 | const SCEV *BaseReg = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx]; | |||
3533 | // Don't generate reassociations for the base register of a value that | |||
3534 | // may generate a post-increment operator. The reason is that the | |||
3535 | // reassociations cause extra base+register formula to be created, | |||
3536 | // and possibly chosen, but the post-increment is more efficient. | |||
3537 | if (TTI.shouldFavorPostInc() && mayUsePostIncMode(TTI, LU, BaseReg, L, SE)) | |||
3538 | return; | |||
3539 | SmallVector<const SCEV *, 8> AddOps; | |||
3540 | const SCEV *Remainder = CollectSubexprs(BaseReg, nullptr, AddOps, L, SE); | |||
3541 | if (Remainder) | |||
3542 | AddOps.push_back(Remainder); | |||
3543 | ||||
3544 | if (AddOps.size() == 1) | |||
3545 | return; | |||
3546 | ||||
3547 | for (SmallVectorImpl<const SCEV *>::const_iterator J = AddOps.begin(), | |||
3548 | JE = AddOps.end(); | |||
3549 | J != JE; ++J) { | |||
3550 | // Loop-variant "unknown" values are uninteresting; we won't be able to | |||
3551 | // do anything meaningful with them. | |||
3552 | if (isa<SCEVUnknown>(*J) && !SE.isLoopInvariant(*J, L)) | |||
3553 | continue; | |||
3554 | ||||
3555 | // Don't pull a constant into a register if the constant could be folded | |||
3556 | // into an immediate field. | |||
3557 | if (isAlwaysFoldable(TTI, SE, LU.MinOffset, LU.MaxOffset, LU.Kind, | |||
3558 | LU.AccessTy, *J, Base.getNumRegs() > 1)) | |||
3559 | continue; | |||
3560 | ||||
3561 | // Collect all operands except *J. | |||
3562 | SmallVector<const SCEV *, 8> InnerAddOps( | |||
3563 | ((const SmallVector<const SCEV *, 8> &)AddOps).begin(), J); | |||
3564 | InnerAddOps.append(std::next(J), | |||
3565 | ((const SmallVector<const SCEV *, 8> &)AddOps).end()); | |||
3566 | ||||
3567 | // Don't leave just a constant behind in a register if the constant could | |||
3568 | // be folded into an immediate field. | |||
3569 | if (InnerAddOps.size() == 1 && | |||
3570 | isAlwaysFoldable(TTI, SE, LU.MinOffset, LU.MaxOffset, LU.Kind, | |||
3571 | LU.AccessTy, InnerAddOps[0], Base.getNumRegs() > 1)) | |||
3572 | continue; | |||
3573 | ||||
3574 | const SCEV *InnerSum = SE.getAddExpr(InnerAddOps); | |||
3575 | if (InnerSum->isZero()) | |||
3576 | continue; | |||
3577 | Formula F = Base; | |||
3578 | ||||
3579 | // Add the remaining pieces of the add back into the new formula. | |||
3580 | const SCEVConstant *InnerSumSC = dyn_cast<SCEVConstant>(InnerSum); | |||
3581 | if (InnerSumSC && SE.getTypeSizeInBits(InnerSumSC->getType()) <= 64 && | |||
3582 | TTI.isLegalAddImmediate((uint64_t)F.UnfoldedOffset + | |||
3583 | InnerSumSC->getValue()->getZExtValue())) { | |||
3584 | F.UnfoldedOffset = | |||
3585 | (uint64_t)F.UnfoldedOffset + InnerSumSC->getValue()->getZExtValue(); | |||
3586 | if (IsScaledReg) | |||
3587 | F.ScaledReg = nullptr; | |||
3588 | else | |||
3589 | F.BaseRegs.erase(F.BaseRegs.begin() + Idx); | |||
3590 | } else if (IsScaledReg) | |||
3591 | F.ScaledReg = InnerSum; | |||
3592 | else | |||
3593 | F.BaseRegs[Idx] = InnerSum; | |||
3594 | ||||
3595 | // Add J as its own register, or an unfolded immediate. | |||
3596 | const SCEVConstant *SC = dyn_cast<SCEVConstant>(*J); | |||
3597 | if (SC && SE.getTypeSizeInBits(SC->getType()) <= 64 && | |||
3598 | TTI.isLegalAddImmediate((uint64_t)F.UnfoldedOffset + | |||
3599 | SC->getValue()->getZExtValue())) | |||
3600 | F.UnfoldedOffset = | |||
3601 | (uint64_t)F.UnfoldedOffset + SC->getValue()->getZExtValue(); | |||
3602 | else | |||
3603 | F.BaseRegs.push_back(*J); | |||
3604 | // We may have changed the number of register in base regs, adjust the | |||
3605 | // formula accordingly. | |||
3606 | F.canonicalize(*L); | |||
3607 | ||||
3608 | if (InsertFormula(LU, LUIdx, F)) | |||
3609 | // If that formula hadn't been seen before, recurse to find more like | |||
3610 | // it. | |||
3611 | // Add check on Log16(AddOps.size()) - same as Log2_32(AddOps.size()) >> 2) | |||
3612 | // Because just Depth is not enough to bound compile time. | |||
3613 | // This means that every time AddOps.size() is greater 16^x we will add | |||
3614 | // x to Depth. | |||
3615 | GenerateReassociations(LU, LUIdx, LU.Formulae.back(), | |||
3616 | Depth + 1 + (Log2_32(AddOps.size()) >> 2)); | |||
3617 | } | |||
3618 | } | |||
3619 | ||||
3620 | /// Split out subexpressions from adds and the bases of addrecs. | |||
3621 | void LSRInstance::GenerateReassociations(LSRUse &LU, unsigned LUIdx, | |||
3622 | Formula Base, unsigned Depth) { | |||
3623 | assert(Base.isCanonical(*L) && "Input must be in the canonical form")(static_cast <bool> (Base.isCanonical(*L) && "Input must be in the canonical form" ) ? void (0) : __assert_fail ("Base.isCanonical(*L) && \"Input must be in the canonical form\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3623, __extension__ __PRETTY_FUNCTION__)); | |||
3624 | // Arbitrarily cap recursion to protect compile time. | |||
3625 | if (Depth >= 3) | |||
3626 | return; | |||
3627 | ||||
3628 | for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i) | |||
3629 | GenerateReassociationsImpl(LU, LUIdx, Base, Depth, i); | |||
3630 | ||||
3631 | if (Base.Scale == 1) | |||
3632 | GenerateReassociationsImpl(LU, LUIdx, Base, Depth, | |||
3633 | /* Idx */ -1, /* IsScaledReg */ true); | |||
3634 | } | |||
3635 | ||||
3636 | /// Generate a formula consisting of all of the loop-dominating registers added | |||
3637 | /// into a single register. | |||
3638 | void LSRInstance::GenerateCombinations(LSRUse &LU, unsigned LUIdx, | |||
3639 | Formula Base) { | |||
3640 | // This method is only interesting on a plurality of registers. | |||
3641 | if (Base.BaseRegs.size() + (Base.Scale == 1) <= 1) | |||
3642 | return; | |||
3643 | ||||
3644 | // Flatten the representation, i.e., reg1 + 1*reg2 => reg1 + reg2, before | |||
3645 | // processing the formula. | |||
3646 | Base.unscale(); | |||
3647 | Formula F = Base; | |||
3648 | F.BaseRegs.clear(); | |||
3649 | SmallVector<const SCEV *, 4> Ops; | |||
3650 | for (const SCEV *BaseReg : Base.BaseRegs) { | |||
3651 | if (SE.properlyDominates(BaseReg, L->getHeader()) && | |||
3652 | !SE.hasComputableLoopEvolution(BaseReg, L)) | |||
3653 | Ops.push_back(BaseReg); | |||
3654 | else | |||
3655 | F.BaseRegs.push_back(BaseReg); | |||
3656 | } | |||
3657 | if (Ops.size() > 1) { | |||
3658 | const SCEV *Sum = SE.getAddExpr(Ops); | |||
3659 | // TODO: If Sum is zero, it probably means ScalarEvolution missed an | |||
3660 | // opportunity to fold something. For now, just ignore such cases | |||
3661 | // rather than proceed with zero in a register. | |||
3662 | if (!Sum->isZero()) { | |||
3663 | F.BaseRegs.push_back(Sum); | |||
3664 | F.canonicalize(*L); | |||
3665 | (void)InsertFormula(LU, LUIdx, F); | |||
3666 | } | |||
3667 | } | |||
3668 | } | |||
3669 | ||||
3670 | /// Helper function for LSRInstance::GenerateSymbolicOffsets. | |||
3671 | void LSRInstance::GenerateSymbolicOffsetsImpl(LSRUse &LU, unsigned LUIdx, | |||
3672 | const Formula &Base, size_t Idx, | |||
3673 | bool IsScaledReg) { | |||
3674 | const SCEV *G = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx]; | |||
3675 | GlobalValue *GV = ExtractSymbol(G, SE); | |||
3676 | if (G->isZero() || !GV) | |||
3677 | return; | |||
3678 | Formula F = Base; | |||
3679 | F.BaseGV = GV; | |||
3680 | if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F)) | |||
3681 | return; | |||
3682 | if (IsScaledReg) | |||
3683 | F.ScaledReg = G; | |||
3684 | else | |||
3685 | F.BaseRegs[Idx] = G; | |||
3686 | (void)InsertFormula(LU, LUIdx, F); | |||
3687 | } | |||
3688 | ||||
3689 | /// Generate reuse formulae using symbolic offsets. | |||
3690 | void LSRInstance::GenerateSymbolicOffsets(LSRUse &LU, unsigned LUIdx, | |||
3691 | Formula Base) { | |||
3692 | // We can't add a symbolic offset if the address already contains one. | |||
3693 | if (Base.BaseGV) return; | |||
3694 | ||||
3695 | for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i) | |||
3696 | GenerateSymbolicOffsetsImpl(LU, LUIdx, Base, i); | |||
3697 | if (Base.Scale == 1) | |||
3698 | GenerateSymbolicOffsetsImpl(LU, LUIdx, Base, /* Idx */ -1, | |||
3699 | /* IsScaledReg */ true); | |||
3700 | } | |||
3701 | ||||
3702 | /// Helper function for LSRInstance::GenerateConstantOffsets. | |||
3703 | void LSRInstance::GenerateConstantOffsetsImpl( | |||
3704 | LSRUse &LU, unsigned LUIdx, const Formula &Base, | |||
3705 | const SmallVectorImpl<int64_t> &Worklist, size_t Idx, bool IsScaledReg) { | |||
3706 | const SCEV *G = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx]; | |||
3707 | for (int64_t Offset : Worklist) { | |||
3708 | Formula F = Base; | |||
3709 | F.BaseOffset = (uint64_t)Base.BaseOffset - Offset; | |||
3710 | if (isLegalUse(TTI, LU.MinOffset - Offset, LU.MaxOffset - Offset, LU.Kind, | |||
3711 | LU.AccessTy, F)) { | |||
3712 | // Add the offset to the base register. | |||
3713 | const SCEV *NewG = SE.getAddExpr(SE.getConstant(G->getType(), Offset), G); | |||
3714 | // If it cancelled out, drop the base register, otherwise update it. | |||
3715 | if (NewG->isZero()) { | |||
3716 | if (IsScaledReg) { | |||
3717 | F.Scale = 0; | |||
3718 | F.ScaledReg = nullptr; | |||
3719 | } else | |||
3720 | F.deleteBaseReg(F.BaseRegs[Idx]); | |||
3721 | F.canonicalize(*L); | |||
3722 | } else if (IsScaledReg) | |||
3723 | F.ScaledReg = NewG; | |||
3724 | else | |||
3725 | F.BaseRegs[Idx] = NewG; | |||
3726 | ||||
3727 | (void)InsertFormula(LU, LUIdx, F); | |||
3728 | } | |||
3729 | } | |||
3730 | ||||
3731 | int64_t Imm = ExtractImmediate(G, SE); | |||
3732 | if (G->isZero() || Imm == 0) | |||
3733 | return; | |||
3734 | Formula F = Base; | |||
3735 | F.BaseOffset = (uint64_t)F.BaseOffset + Imm; | |||
3736 | if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F)) | |||
3737 | return; | |||
3738 | if (IsScaledReg) | |||
3739 | F.ScaledReg = G; | |||
3740 | else | |||
3741 | F.BaseRegs[Idx] = G; | |||
3742 | (void)InsertFormula(LU, LUIdx, F); | |||
3743 | } | |||
3744 | ||||
3745 | /// GenerateConstantOffsets - Generate reuse formulae using symbolic offsets. | |||
3746 | void LSRInstance::GenerateConstantOffsets(LSRUse &LU, unsigned LUIdx, | |||
3747 | Formula Base) { | |||
3748 | // TODO: For now, just add the min and max offset, because it usually isn't | |||
3749 | // worthwhile looking at everything inbetween. | |||
3750 | SmallVector<int64_t, 2> Worklist; | |||
3751 | Worklist.push_back(LU.MinOffset); | |||
3752 | if (LU.MaxOffset != LU.MinOffset) | |||
3753 | Worklist.push_back(LU.MaxOffset); | |||
3754 | ||||
3755 | for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i) | |||
3756 | GenerateConstantOffsetsImpl(LU, LUIdx, Base, Worklist, i); | |||
3757 | if (Base.Scale == 1) | |||
3758 | GenerateConstantOffsetsImpl(LU, LUIdx, Base, Worklist, /* Idx */ -1, | |||
3759 | /* IsScaledReg */ true); | |||
3760 | } | |||
3761 | ||||
3762 | /// For ICmpZero, check to see if we can scale up the comparison. For example, x | |||
3763 | /// == y -> x*c == y*c. | |||
3764 | void LSRInstance::GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx, | |||
3765 | Formula Base) { | |||
3766 | if (LU.Kind != LSRUse::ICmpZero) return; | |||
3767 | ||||
3768 | // Determine the integer type for the base formula. | |||
3769 | Type *IntTy = Base.getType(); | |||
3770 | if (!IntTy) return; | |||
3771 | if (SE.getTypeSizeInBits(IntTy) > 64) return; | |||
3772 | ||||
3773 | // Don't do this if there is more than one offset. | |||
3774 | if (LU.MinOffset != LU.MaxOffset) return; | |||
3775 | ||||
3776 | // Check if transformation is valid. It is illegal to multiply pointer. | |||
3777 | if (Base.ScaledReg && Base.ScaledReg->getType()->isPointerTy()) | |||
3778 | return; | |||
3779 | for (const SCEV *BaseReg : Base.BaseRegs) | |||
3780 | if (BaseReg->getType()->isPointerTy()) | |||
3781 | return; | |||
3782 | assert(!Base.BaseGV && "ICmpZero use is not legal!")(static_cast <bool> (!Base.BaseGV && "ICmpZero use is not legal!" ) ? void (0) : __assert_fail ("!Base.BaseGV && \"ICmpZero use is not legal!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3782, __extension__ __PRETTY_FUNCTION__)); | |||
3783 | ||||
3784 | // Check each interesting stride. | |||
3785 | for (int64_t Factor : Factors) { | |||
3786 | // Check that the multiplication doesn't overflow. | |||
3787 | if (Base.BaseOffset == std::numeric_limits<int64_t>::min() && Factor == -1) | |||
3788 | continue; | |||
3789 | int64_t NewBaseOffset = (uint64_t)Base.BaseOffset * Factor; | |||
3790 | if (NewBaseOffset / Factor != Base.BaseOffset) | |||
3791 | continue; | |||
3792 | // If the offset will be truncated at this use, check that it is in bounds. | |||
3793 | if (!IntTy->isPointerTy() && | |||
3794 | !ConstantInt::isValueValidForType(IntTy, NewBaseOffset)) | |||
3795 | continue; | |||
3796 | ||||
3797 | // Check that multiplying with the use offset doesn't overflow. | |||
3798 | int64_t Offset = LU.MinOffset; | |||
3799 | if (Offset == std::numeric_limits<int64_t>::min() && Factor == -1) | |||
3800 | continue; | |||
3801 | Offset = (uint64_t)Offset * Factor; | |||
3802 | if (Offset / Factor != LU.MinOffset) | |||
3803 | continue; | |||
3804 | // If the offset will be truncated at this use, check that it is in bounds. | |||
3805 | if (!IntTy->isPointerTy() && | |||
3806 | !ConstantInt::isValueValidForType(IntTy, Offset)) | |||
3807 | continue; | |||
3808 | ||||
3809 | Formula F = Base; | |||
3810 | F.BaseOffset = NewBaseOffset; | |||
3811 | ||||
3812 | // Check that this scale is legal. | |||
3813 | if (!isLegalUse(TTI, Offset, Offset, LU.Kind, LU.AccessTy, F)) | |||
3814 | continue; | |||
3815 | ||||
3816 | // Compensate for the use having MinOffset built into it. | |||
3817 | F.BaseOffset = (uint64_t)F.BaseOffset + Offset - LU.MinOffset; | |||
3818 | ||||
3819 | const SCEV *FactorS = SE.getConstant(IntTy, Factor); | |||
3820 | ||||
3821 | // Check that multiplying with each base register doesn't overflow. | |||
3822 | for (size_t i = 0, e = F.BaseRegs.size(); i != e; ++i) { | |||
3823 | F.BaseRegs[i] = SE.getMulExpr(F.BaseRegs[i], FactorS); | |||
3824 | if (getExactSDiv(F.BaseRegs[i], FactorS, SE) != Base.BaseRegs[i]) | |||
3825 | goto next; | |||
3826 | } | |||
3827 | ||||
3828 | // Check that multiplying with the scaled register doesn't overflow. | |||
3829 | if (F.ScaledReg) { | |||
3830 | F.ScaledReg = SE.getMulExpr(F.ScaledReg, FactorS); | |||
3831 | if (getExactSDiv(F.ScaledReg, FactorS, SE) != Base.ScaledReg) | |||
3832 | continue; | |||
3833 | } | |||
3834 | ||||
3835 | // Check that multiplying with the unfolded offset doesn't overflow. | |||
3836 | if (F.UnfoldedOffset != 0) { | |||
3837 | if (F.UnfoldedOffset == std::numeric_limits<int64_t>::min() && | |||
3838 | Factor == -1) | |||
3839 | continue; | |||
3840 | F.UnfoldedOffset = (uint64_t)F.UnfoldedOffset * Factor; | |||
3841 | if (F.UnfoldedOffset / Factor != Base.UnfoldedOffset) | |||
3842 | continue; | |||
3843 | // If the offset will be truncated, check that it is in bounds. | |||
3844 | if (!IntTy->isPointerTy() && | |||
3845 | !ConstantInt::isValueValidForType(IntTy, F.UnfoldedOffset)) | |||
3846 | continue; | |||
3847 | } | |||
3848 | ||||
3849 | // If we make it here and it's legal, add it. | |||
3850 | (void)InsertFormula(LU, LUIdx, F); | |||
3851 | next:; | |||
3852 | } | |||
3853 | } | |||
3854 | ||||
3855 | /// Generate stride factor reuse formulae by making use of scaled-offset address | |||
3856 | /// modes, for example. | |||
3857 | void LSRInstance::GenerateScales(LSRUse &LU, unsigned LUIdx, Formula Base) { | |||
3858 | // Determine the integer type for the base formula. | |||
3859 | Type *IntTy = Base.getType(); | |||
3860 | if (!IntTy) return; | |||
3861 | ||||
3862 | // If this Formula already has a scaled register, we can't add another one. | |||
3863 | // Try to unscale the formula to generate a better scale. | |||
3864 | if (Base.Scale != 0 && !Base.unscale()) | |||
3865 | return; | |||
3866 | ||||
3867 | assert(Base.Scale == 0 && "unscale did not did its job!")(static_cast <bool> (Base.Scale == 0 && "unscale did not did its job!" ) ? void (0) : __assert_fail ("Base.Scale == 0 && \"unscale did not did its job!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 3867, __extension__ __PRETTY_FUNCTION__)); | |||
3868 | ||||
3869 | // Check each interesting stride. | |||
3870 | for (int64_t Factor : Factors) { | |||
3871 | Base.Scale = Factor; | |||
3872 | Base.HasBaseReg = Base.BaseRegs.size() > 1; | |||
3873 | // Check whether this scale is going to be legal. | |||
3874 | if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, | |||
3875 | Base)) { | |||
3876 | // As a special-case, handle special out-of-loop Basic users specially. | |||
3877 | // TODO: Reconsider this special case. | |||
3878 | if (LU.Kind == LSRUse::Basic && | |||
3879 | isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LSRUse::Special, | |||
3880 | LU.AccessTy, Base) && | |||
3881 | LU.AllFixupsOutsideLoop) | |||
3882 | LU.Kind = LSRUse::Special; | |||
3883 | else | |||
3884 | continue; | |||
3885 | } | |||
3886 | // For an ICmpZero, negating a solitary base register won't lead to | |||
3887 | // new solutions. | |||
3888 | if (LU.Kind == LSRUse::ICmpZero && | |||
3889 | !Base.HasBaseReg && Base.BaseOffset == 0 && !Base.BaseGV) | |||
3890 | continue; | |||
3891 | // For each addrec base reg, if its loop is current loop, apply the scale. | |||
3892 | for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i) { | |||
3893 | const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Base.BaseRegs[i]); | |||
3894 | if (AR && (AR->getLoop() == L || LU.AllFixupsOutsideLoop)) { | |||
3895 | const SCEV *FactorS = SE.getConstant(IntTy, Factor); | |||
3896 | if (FactorS->isZero()) | |||
3897 | continue; | |||
3898 | // Divide out the factor, ignoring high bits, since we'll be | |||
3899 | // scaling the value back up in the end. | |||
3900 | if (const SCEV *Quotient = getExactSDiv(AR, FactorS, SE, true)) { | |||
3901 | // TODO: This could be optimized to avoid all the copying. | |||
3902 | Formula F = Base; | |||
3903 | F.ScaledReg = Quotient; | |||
3904 | F.deleteBaseReg(F.BaseRegs[i]); | |||
3905 | // The canonical representation of 1*reg is reg, which is already in | |||
3906 | // Base. In that case, do not try to insert the formula, it will be | |||
3907 | // rejected anyway. | |||
3908 | if (F.Scale == 1 && (F.BaseRegs.empty() || | |||
3909 | (AR->getLoop() != L && LU.AllFixupsOutsideLoop))) | |||
3910 | continue; | |||
3911 | // If AllFixupsOutsideLoop is true and F.Scale is 1, we may generate | |||
3912 | // non canonical Formula with ScaledReg's loop not being L. | |||
3913 | if (F.Scale == 1 && LU.AllFixupsOutsideLoop) | |||
3914 | F.canonicalize(*L); | |||
3915 | (void)InsertFormula(LU, LUIdx, F); | |||
3916 | } | |||
3917 | } | |||
3918 | } | |||
3919 | } | |||
3920 | } | |||
3921 | ||||
3922 | /// Generate reuse formulae from different IV types. | |||
3923 | void LSRInstance::GenerateTruncates(LSRUse &LU, unsigned LUIdx, Formula Base) { | |||
3924 | // Don't bother truncating symbolic values. | |||
3925 | if (Base.BaseGV) return; | |||
3926 | ||||
3927 | // Determine the integer type for the base formula. | |||
3928 | Type *DstTy = Base.getType(); | |||
3929 | if (!DstTy) return; | |||
3930 | DstTy = SE.getEffectiveSCEVType(DstTy); | |||
3931 | ||||
3932 | for (Type *SrcTy : Types) { | |||
3933 | if (SrcTy != DstTy && TTI.isTruncateFree(SrcTy, DstTy)) { | |||
3934 | Formula F = Base; | |||
3935 | ||||
3936 | if (F.ScaledReg) F.ScaledReg = SE.getAnyExtendExpr(F.ScaledReg, SrcTy); | |||
3937 | for (const SCEV *&BaseReg : F.BaseRegs) | |||
3938 | BaseReg = SE.getAnyExtendExpr(BaseReg, SrcTy); | |||
3939 | ||||
3940 | // TODO: This assumes we've done basic processing on all uses and | |||
3941 | // have an idea what the register usage is. | |||
3942 | if (!F.hasRegsUsedByUsesOtherThan(LUIdx, RegUses)) | |||
3943 | continue; | |||
3944 | ||||
3945 | F.canonicalize(*L); | |||
3946 | (void)InsertFormula(LU, LUIdx, F); | |||
3947 | } | |||
3948 | } | |||
3949 | } | |||
3950 | ||||
3951 | namespace { | |||
3952 | ||||
3953 | /// Helper class for GenerateCrossUseConstantOffsets. It's used to defer | |||
3954 | /// modifications so that the search phase doesn't have to worry about the data | |||
3955 | /// structures moving underneath it. | |||
3956 | struct WorkItem { | |||
3957 | size_t LUIdx; | |||
3958 | int64_t Imm; | |||
3959 | const SCEV *OrigReg; | |||
3960 | ||||
3961 | WorkItem(size_t LI, int64_t I, const SCEV *R) | |||
3962 | : LUIdx(LI), Imm(I), OrigReg(R) {} | |||
3963 | ||||
3964 | void print(raw_ostream &OS) const; | |||
3965 | void dump() const; | |||
3966 | }; | |||
3967 | ||||
3968 | } // end anonymous namespace | |||
3969 | ||||
3970 | #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) | |||
3971 | void WorkItem::print(raw_ostream &OS) const { | |||
3972 | OS << "in formulae referencing " << *OrigReg << " in use " << LUIdx | |||
3973 | << " , add offset " << Imm; | |||
3974 | } | |||
3975 | ||||
3976 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void WorkItem::dump() const { | |||
3977 | print(errs()); errs() << '\n'; | |||
3978 | } | |||
3979 | #endif | |||
3980 | ||||
3981 | /// Look for registers which are a constant distance apart and try to form reuse | |||
3982 | /// opportunities between them. | |||
3983 | void LSRInstance::GenerateCrossUseConstantOffsets() { | |||
3984 | // Group the registers by their value without any added constant offset. | |||
3985 | using ImmMapTy = std::map<int64_t, const SCEV *>; | |||
3986 | ||||
3987 | DenseMap<const SCEV *, ImmMapTy> Map; | |||
3988 | DenseMap<const SCEV *, SmallBitVector> UsedByIndicesMap; | |||
3989 | SmallVector<const SCEV *, 8> Sequence; | |||
3990 | for (const SCEV *Use : RegUses) { | |||
3991 | const SCEV *Reg = Use; // Make a copy for ExtractImmediate to modify. | |||
3992 | int64_t Imm = ExtractImmediate(Reg, SE); | |||
3993 | auto Pair = Map.insert(std::make_pair(Reg, ImmMapTy())); | |||
3994 | if (Pair.second) | |||
3995 | Sequence.push_back(Reg); | |||
3996 | Pair.first->second.insert(std::make_pair(Imm, Use)); | |||
3997 | UsedByIndicesMap[Reg] |= RegUses.getUsedByIndices(Use); | |||
3998 | } | |||
3999 | ||||
4000 | // Now examine each set of registers with the same base value. Build up | |||
4001 | // a list of work to do and do the work in a separate step so that we're | |||
4002 | // not adding formulae and register counts while we're searching. | |||
4003 | SmallVector<WorkItem, 32> WorkItems; | |||
4004 | SmallSet<std::pair<size_t, int64_t>, 32> UniqueItems; | |||
4005 | for (const SCEV *Reg : Sequence) { | |||
4006 | const ImmMapTy &Imms = Map.find(Reg)->second; | |||
4007 | ||||
4008 | // It's not worthwhile looking for reuse if there's only one offset. | |||
4009 | if (Imms.size() == 1) | |||
4010 | continue; | |||
4011 | ||||
4012 | LLVM_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) | |||
4013 | for (const auto &Entrydo { 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) | |||
4014 | : Imms) dbgs()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) | |||
4015 | << ' ' << 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) | |||
4016 | 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); | |||
4017 | ||||
4018 | // Examine each offset. | |||
4019 | for (ImmMapTy::const_iterator J = Imms.begin(), JE = Imms.end(); | |||
4020 | J != JE; ++J) { | |||
4021 | const SCEV *OrigReg = J->second; | |||
4022 | ||||
4023 | int64_t JImm = J->first; | |||
4024 | const SmallBitVector &UsedByIndices = RegUses.getUsedByIndices(OrigReg); | |||
4025 | ||||
4026 | if (!isa<SCEVConstant>(OrigReg) && | |||
4027 | UsedByIndicesMap[Reg].count() == 1) { | |||
4028 | LLVM_DEBUG(dbgs() << "Skipping cross-use reuse for " << *OrigRegdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Skipping cross-use reuse for " << *OrigReg << '\n'; } } while (false) | |||
4029 | << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Skipping cross-use reuse for " << *OrigReg << '\n'; } } while (false); | |||
4030 | continue; | |||
4031 | } | |||
4032 | ||||
4033 | // Conservatively examine offsets between this orig reg a few selected | |||
4034 | // other orig regs. | |||
4035 | ImmMapTy::const_iterator OtherImms[] = { | |||
4036 | Imms.begin(), std::prev(Imms.end()), | |||
4037 | Imms.lower_bound((Imms.begin()->first + std::prev(Imms.end())->first) / | |||
4038 | 2) | |||
4039 | }; | |||
4040 | for (size_t i = 0, e = array_lengthof(OtherImms); i != e; ++i) { | |||
4041 | ImmMapTy::const_iterator M = OtherImms[i]; | |||
4042 | if (M == J || M == JE) continue; | |||
4043 | ||||
4044 | // Compute the difference between the two. | |||
4045 | int64_t Imm = (uint64_t)JImm - M->first; | |||
4046 | for (unsigned LUIdx : UsedByIndices.set_bits()) | |||
4047 | // Make a memo of this use, offset, and register tuple. | |||
4048 | if (UniqueItems.insert(std::make_pair(LUIdx, Imm)).second) | |||
4049 | WorkItems.push_back(WorkItem(LUIdx, Imm, OrigReg)); | |||
4050 | } | |||
4051 | } | |||
4052 | } | |||
4053 | ||||
4054 | Map.clear(); | |||
4055 | Sequence.clear(); | |||
4056 | UsedByIndicesMap.clear(); | |||
4057 | UniqueItems.clear(); | |||
4058 | ||||
4059 | // Now iterate through the worklist and add new formulae. | |||
4060 | for (const WorkItem &WI : WorkItems) { | |||
4061 | size_t LUIdx = WI.LUIdx; | |||
4062 | LSRUse &LU = Uses[LUIdx]; | |||
4063 | int64_t Imm = WI.Imm; | |||
4064 | const SCEV *OrigReg = WI.OrigReg; | |||
4065 | ||||
4066 | Type *IntTy = SE.getEffectiveSCEVType(OrigReg->getType()); | |||
4067 | const SCEV *NegImmS = SE.getSCEV(ConstantInt::get(IntTy, -(uint64_t)Imm)); | |||
4068 | unsigned BitWidth = SE.getTypeSizeInBits(IntTy); | |||
4069 | ||||
4070 | // TODO: Use a more targeted data structure. | |||
4071 | for (size_t L = 0, LE = LU.Formulae.size(); L != LE; ++L) { | |||
4072 | Formula F = LU.Formulae[L]; | |||
4073 | // FIXME: The code for the scaled and unscaled registers looks | |||
4074 | // very similar but slightly different. Investigate if they | |||
4075 | // could be merged. That way, we would not have to unscale the | |||
4076 | // Formula. | |||
4077 | F.unscale(); | |||
4078 | // Use the immediate in the scaled register. | |||
4079 | if (F.ScaledReg == OrigReg) { | |||
4080 | int64_t Offset = (uint64_t)F.BaseOffset + Imm * (uint64_t)F.Scale; | |||
4081 | // Don't create 50 + reg(-50). | |||
4082 | if (F.referencesReg(SE.getSCEV( | |||
4083 | ConstantInt::get(IntTy, -(uint64_t)Offset)))) | |||
4084 | continue; | |||
4085 | Formula NewF = F; | |||
4086 | NewF.BaseOffset = Offset; | |||
4087 | if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, | |||
4088 | NewF)) | |||
4089 | continue; | |||
4090 | NewF.ScaledReg = SE.getAddExpr(NegImmS, NewF.ScaledReg); | |||
4091 | ||||
4092 | // If the new scale is a constant in a register, and adding the constant | |||
4093 | // value to the immediate would produce a value closer to zero than the | |||
4094 | // immediate itself, then the formula isn't worthwhile. | |||
4095 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(NewF.ScaledReg)) | |||
4096 | if (C->getValue()->isNegative() != (NewF.BaseOffset < 0) && | |||
4097 | (C->getAPInt().abs() * APInt(BitWidth, F.Scale)) | |||
4098 | .ule(std::abs(NewF.BaseOffset))) | |||
4099 | continue; | |||
4100 | ||||
4101 | // OK, looks good. | |||
4102 | NewF.canonicalize(*this->L); | |||
4103 | (void)InsertFormula(LU, LUIdx, NewF); | |||
4104 | } else { | |||
4105 | // Use the immediate in a base register. | |||
4106 | for (size_t N = 0, NE = F.BaseRegs.size(); N != NE; ++N) { | |||
4107 | const SCEV *BaseReg = F.BaseRegs[N]; | |||
4108 | if (BaseReg != OrigReg) | |||
4109 | continue; | |||
4110 | Formula NewF = F; | |||
4111 | NewF.BaseOffset = (uint64_t)NewF.BaseOffset + Imm; | |||
4112 | if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, | |||
4113 | LU.Kind, LU.AccessTy, NewF)) { | |||
4114 | if (TTI.shouldFavorPostInc() && | |||
4115 | mayUsePostIncMode(TTI, LU, OrigReg, this->L, SE)) | |||
4116 | continue; | |||
4117 | if (!TTI.isLegalAddImmediate((uint64_t)NewF.UnfoldedOffset + Imm)) | |||
4118 | continue; | |||
4119 | NewF = F; | |||
4120 | NewF.UnfoldedOffset = (uint64_t)NewF.UnfoldedOffset + Imm; | |||
4121 | } | |||
4122 | NewF.BaseRegs[N] = SE.getAddExpr(NegImmS, BaseReg); | |||
4123 | ||||
4124 | // If the new formula has a constant in a register, and adding the | |||
4125 | // constant value to the immediate would produce a value closer to | |||
4126 | // zero than the immediate itself, then the formula isn't worthwhile. | |||
4127 | for (const SCEV *NewReg : NewF.BaseRegs) | |||
4128 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(NewReg)) | |||
4129 | if ((C->getAPInt() + NewF.BaseOffset) | |||
4130 | .abs() | |||
4131 | .slt(std::abs(NewF.BaseOffset)) && | |||
4132 | (C->getAPInt() + NewF.BaseOffset).countTrailingZeros() >= | |||
4133 | countTrailingZeros<uint64_t>(NewF.BaseOffset)) | |||
4134 | goto skip_formula; | |||
4135 | ||||
4136 | // Ok, looks good. | |||
4137 | NewF.canonicalize(*this->L); | |||
4138 | (void)InsertFormula(LU, LUIdx, NewF); | |||
4139 | break; | |||
4140 | skip_formula:; | |||
4141 | } | |||
4142 | } | |||
4143 | } | |||
4144 | } | |||
4145 | } | |||
4146 | ||||
4147 | /// Generate formulae for each use. | |||
4148 | void | |||
4149 | LSRInstance::GenerateAllReuseFormulae() { | |||
4150 | // This is split into multiple loops so that hasRegsUsedByUsesOtherThan | |||
4151 | // queries are more precise. | |||
4152 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { | |||
4153 | LSRUse &LU = Uses[LUIdx]; | |||
4154 | for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) | |||
4155 | GenerateReassociations(LU, LUIdx, LU.Formulae[i]); | |||
4156 | for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) | |||
4157 | GenerateCombinations(LU, LUIdx, LU.Formulae[i]); | |||
4158 | } | |||
4159 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { | |||
4160 | LSRUse &LU = Uses[LUIdx]; | |||
4161 | for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) | |||
4162 | GenerateSymbolicOffsets(LU, LUIdx, LU.Formulae[i]); | |||
4163 | for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) | |||
4164 | GenerateConstantOffsets(LU, LUIdx, LU.Formulae[i]); | |||
4165 | for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) | |||
4166 | GenerateICmpZeroScales(LU, LUIdx, LU.Formulae[i]); | |||
4167 | for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) | |||
4168 | GenerateScales(LU, LUIdx, LU.Formulae[i]); | |||
4169 | } | |||
4170 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { | |||
4171 | LSRUse &LU = Uses[LUIdx]; | |||
4172 | for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) | |||
4173 | GenerateTruncates(LU, LUIdx, LU.Formulae[i]); | |||
4174 | } | |||
4175 | ||||
4176 | GenerateCrossUseConstantOffsets(); | |||
4177 | ||||
4178 | LLVM_DEBUG(dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\n" "After generating reuse formulae:\n" ; print_uses(dbgs()); } } while (false) | |||
4179 | "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) | |||
4180 | print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\n" "After generating reuse formulae:\n" ; print_uses(dbgs()); } } while (false); | |||
4181 | } | |||
4182 | ||||
4183 | /// If there are multiple formulae with the same set of registers used | |||
4184 | /// by other uses, pick the best one and delete the others. | |||
4185 | void LSRInstance::FilterOutUndesirableDedicatedRegisters() { | |||
4186 | DenseSet<const SCEV *> VisitedRegs; | |||
4187 | SmallPtrSet<const SCEV *, 16> Regs; | |||
4188 | SmallPtrSet<const SCEV *, 16> LoserRegs; | |||
4189 | #ifndef NDEBUG | |||
4190 | bool ChangedFormulae = false; | |||
4191 | #endif | |||
4192 | ||||
4193 | // Collect the best formula for each unique set of shared registers. This | |||
4194 | // is reset for each use. | |||
4195 | using BestFormulaeTy = | |||
4196 | DenseMap<SmallVector<const SCEV *, 4>, size_t, UniquifierDenseMapInfo>; | |||
4197 | ||||
4198 | BestFormulaeTy BestFormulae; | |||
4199 | ||||
4200 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { | |||
4201 | LSRUse &LU = Uses[LUIdx]; | |||
4202 | LLVM_DEBUG(dbgs() << "Filtering for use "; LU.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Filtering for use "; LU.print (dbgs()); dbgs() << '\n'; } } while (false) | |||
4203 | dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Filtering for use "; LU.print (dbgs()); dbgs() << '\n'; } } while (false); | |||
4204 | ||||
4205 | bool Any = false; | |||
4206 | for (size_t FIdx = 0, NumForms = LU.Formulae.size(); | |||
4207 | FIdx != NumForms; ++FIdx) { | |||
4208 | Formula &F = LU.Formulae[FIdx]; | |||
4209 | ||||
4210 | // Some formulas are instant losers. For example, they may depend on | |||
4211 | // nonexistent AddRecs from other loops. These need to be filtered | |||
4212 | // immediately, otherwise heuristics could choose them over others leading | |||
4213 | // to an unsatisfactory solution. Passing LoserRegs into RateFormula here | |||
4214 | // avoids the need to recompute this information across formulae using the | |||
4215 | // same bad AddRec. Passing LoserRegs is also essential unless we remove | |||
4216 | // the corresponding bad register from the Regs set. | |||
4217 | Cost CostF; | |||
4218 | Regs.clear(); | |||
4219 | CostF.RateFormula(TTI, F, Regs, VisitedRegs, L, SE, DT, LU, &LoserRegs); | |||
4220 | if (CostF.isLoser()) { | |||
4221 | // During initial formula generation, undesirable formulae are generated | |||
4222 | // by uses within other loops that have some non-trivial address mode or | |||
4223 | // use the postinc form of the IV. LSR needs to provide these formulae | |||
4224 | // as the basis of rediscovering the desired formula that uses an AddRec | |||
4225 | // corresponding to the existing phi. Once all formulae have been | |||
4226 | // generated, these initial losers may be pruned. | |||
4227 | LLVM_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) | |||
4228 | dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Filtering loser "; F.print (dbgs()); dbgs() << "\n"; } } while (false); | |||
4229 | } | |||
4230 | else { | |||
4231 | SmallVector<const SCEV *, 4> Key; | |||
4232 | for (const SCEV *Reg : F.BaseRegs) { | |||
4233 | if (RegUses.isRegUsedByUsesOtherThan(Reg, LUIdx)) | |||
4234 | Key.push_back(Reg); | |||
4235 | } | |||
4236 | if (F.ScaledReg && | |||
4237 | RegUses.isRegUsedByUsesOtherThan(F.ScaledReg, LUIdx)) | |||
4238 | Key.push_back(F.ScaledReg); | |||
4239 | // Unstable sort by host order ok, because this is only used for | |||
4240 | // uniquifying. | |||
4241 | llvm::sort(Key.begin(), Key.end()); | |||
4242 | ||||
4243 | std::pair<BestFormulaeTy::const_iterator, bool> P = | |||
4244 | BestFormulae.insert(std::make_pair(Key, FIdx)); | |||
4245 | if (P.second) | |||
4246 | continue; | |||
4247 | ||||
4248 | Formula &Best = LU.Formulae[P.first->second]; | |||
4249 | ||||
4250 | Cost CostBest; | |||
4251 | Regs.clear(); | |||
4252 | CostBest.RateFormula(TTI, Best, Regs, VisitedRegs, L, SE, DT, LU); | |||
4253 | if (CostF.isLess(CostBest, TTI)) | |||
4254 | std::swap(F, Best); | |||
4255 | LLVM_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) | |||
4256 | 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) | |||
4257 | " in favor of formula ";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) | |||
4258 | Best.print(dbgs()); 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); | |||
4259 | } | |||
4260 | #ifndef NDEBUG | |||
4261 | ChangedFormulae = true; | |||
4262 | #endif | |||
4263 | LU.DeleteFormula(F); | |||
4264 | --FIdx; | |||
4265 | --NumForms; | |||
4266 | Any = true; | |||
4267 | } | |||
4268 | ||||
4269 | // Now that we've filtered out some formulae, recompute the Regs set. | |||
4270 | if (Any) | |||
4271 | LU.RecomputeRegs(LUIdx, RegUses); | |||
4272 | ||||
4273 | // Reset this to prepare for the next use. | |||
4274 | BestFormulae.clear(); | |||
4275 | } | |||
4276 | ||||
4277 | LLVM_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) | |||
4278 | 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) | |||
4279 | "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) | |||
4280 | 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) | |||
4281 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n" "After filtering out undesirable candidates:\n"; print_uses( dbgs()); }; } } while (false); | |||
4282 | } | |||
4283 | ||||
4284 | // This is a rough guess that seems to work fairly well. | |||
4285 | static const size_t ComplexityLimit = std::numeric_limits<uint16_t>::max(); | |||
4286 | ||||
4287 | /// Estimate the worst-case number of solutions the solver might have to | |||
4288 | /// consider. It almost never considers this many solutions because it prune the | |||
4289 | /// search space, but the pruning isn't always sufficient. | |||
4290 | size_t LSRInstance::EstimateSearchSpaceComplexity() const { | |||
4291 | size_t Power = 1; | |||
4292 | for (const LSRUse &LU : Uses) { | |||
4293 | size_t FSize = LU.Formulae.size(); | |||
4294 | if (FSize >= ComplexityLimit) { | |||
4295 | Power = ComplexityLimit; | |||
4296 | break; | |||
4297 | } | |||
4298 | Power *= FSize; | |||
4299 | if (Power >= ComplexityLimit) | |||
4300 | break; | |||
4301 | } | |||
4302 | return Power; | |||
4303 | } | |||
4304 | ||||
4305 | /// When one formula uses a superset of the registers of another formula, it | |||
4306 | /// won't help reduce register pressure (though it may not necessarily hurt | |||
4307 | /// register pressure); remove it to simplify the system. | |||
4308 | void LSRInstance::NarrowSearchSpaceByDetectingSupersets() { | |||
4309 | if (EstimateSearchSpaceComplexity() >= ComplexityLimit) { | |||
4310 | LLVM_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); | |||
4311 | ||||
4312 | LLVM_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) | |||
4313 | "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) | |||
4314 | "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); | |||
4315 | ||||
4316 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { | |||
4317 | LSRUse &LU = Uses[LUIdx]; | |||
4318 | bool Any = false; | |||
4319 | for (size_t i = 0, e = LU.Formulae.size(); i != e; ++i) { | |||
4320 | Formula &F = LU.Formulae[i]; | |||
4321 | // Look for a formula with a constant or GV in a register. If the use | |||
4322 | // also has a formula with that same value in an immediate field, | |||
4323 | // delete the one that uses a register. | |||
4324 | for (SmallVectorImpl<const SCEV *>::const_iterator | |||
4325 | I = F.BaseRegs.begin(), E = F.BaseRegs.end(); I != E; ++I) { | |||
4326 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(*I)) { | |||
4327 | Formula NewF = F; | |||
4328 | NewF.BaseOffset += C->getValue()->getSExtValue(); | |||
4329 | NewF.BaseRegs.erase(NewF.BaseRegs.begin() + | |||
4330 | (I - F.BaseRegs.begin())); | |||
4331 | if (LU.HasFormulaWithSameRegs(NewF)) { | |||
4332 | LLVM_DEBUG(dbgs() << " Deleting "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs ()); dbgs() << '\n'; } } while (false) | |||
4333 | dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs ()); dbgs() << '\n'; } } while (false); | |||
4334 | LU.DeleteFormula(F); | |||
4335 | --i; | |||
4336 | --e; | |||
4337 | Any = true; | |||
4338 | break; | |||
4339 | } | |||
4340 | } else if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(*I)) { | |||
4341 | if (GlobalValue *GV = dyn_cast<GlobalValue>(U->getValue())) | |||
4342 | if (!F.BaseGV) { | |||
4343 | Formula NewF = F; | |||
4344 | NewF.BaseGV = GV; | |||
4345 | NewF.BaseRegs.erase(NewF.BaseRegs.begin() + | |||
4346 | (I - F.BaseRegs.begin())); | |||
4347 | if (LU.HasFormulaWithSameRegs(NewF)) { | |||
4348 | LLVM_DEBUG(dbgs() << " Deleting "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs ()); dbgs() << '\n'; } } while (false) | |||
4349 | dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs ()); dbgs() << '\n'; } } while (false); | |||
4350 | LU.DeleteFormula(F); | |||
4351 | --i; | |||
4352 | --e; | |||
4353 | Any = true; | |||
4354 | break; | |||
4355 | } | |||
4356 | } | |||
4357 | } | |||
4358 | } | |||
4359 | } | |||
4360 | if (Any) | |||
4361 | LU.RecomputeRegs(LUIdx, RegUses); | |||
4362 | } | |||
4363 | ||||
4364 | LLVM_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); | |||
4365 | } | |||
4366 | } | |||
4367 | ||||
4368 | /// When there are many registers for expressions like A, A+1, A+2, etc., | |||
4369 | /// allocate a single register for them. | |||
4370 | void LSRInstance::NarrowSearchSpaceByCollapsingUnrolledCode() { | |||
4371 | if (EstimateSearchSpaceComplexity() < ComplexityLimit) | |||
4372 | return; | |||
4373 | ||||
4374 | LLVM_DEBUG(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) | |||
4375 | 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) | |||
4376 | "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) | |||
4377 | "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); | |||
4378 | ||||
4379 | // This is especially useful for unrolled loops. | |||
4380 | ||||
4381 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { | |||
4382 | LSRUse &LU = Uses[LUIdx]; | |||
4383 | for (const Formula &F : LU.Formulae) { | |||
4384 | if (F.BaseOffset == 0 || (F.Scale != 0 && F.Scale != 1)) | |||
4385 | continue; | |||
4386 | ||||
4387 | LSRUse *LUThatHas = FindUseWithSimilarFormula(F, LU); | |||
4388 | if (!LUThatHas) | |||
4389 | continue; | |||
4390 | ||||
4391 | if (!reconcileNewOffset(*LUThatHas, F.BaseOffset, /*HasBaseReg=*/ false, | |||
4392 | LU.Kind, LU.AccessTy)) | |||
4393 | continue; | |||
4394 | ||||
4395 | LLVM_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); | |||
4396 | ||||
4397 | LUThatHas->AllFixupsOutsideLoop &= LU.AllFixupsOutsideLoop; | |||
4398 | ||||
4399 | // Transfer the fixups of LU to LUThatHas. | |||
4400 | for (LSRFixup &Fixup : LU.Fixups) { | |||
4401 | Fixup.Offset += F.BaseOffset; | |||
4402 | LUThatHas->pushFixup(Fixup); | |||
4403 | LLVM_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); | |||
4404 | } | |||
4405 | ||||
4406 | // Delete formulae from the new use which are no longer legal. | |||
4407 | bool Any = false; | |||
4408 | for (size_t i = 0, e = LUThatHas->Formulae.size(); i != e; ++i) { | |||
4409 | Formula &F = LUThatHas->Formulae[i]; | |||
4410 | if (!isLegalUse(TTI, LUThatHas->MinOffset, LUThatHas->MaxOffset, | |||
4411 | LUThatHas->Kind, LUThatHas->AccessTy, F)) { | |||
4412 | LLVM_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); | |||
4413 | LUThatHas->DeleteFormula(F); | |||
4414 | --i; | |||
4415 | --e; | |||
4416 | Any = true; | |||
4417 | } | |||
4418 | } | |||
4419 | ||||
4420 | if (Any) | |||
4421 | LUThatHas->RecomputeRegs(LUThatHas - &Uses.front(), RegUses); | |||
4422 | ||||
4423 | // Delete the old use. | |||
4424 | DeleteUse(LU, LUIdx); | |||
4425 | --LUIdx; | |||
4426 | --NumUses; | |||
4427 | break; | |||
4428 | } | |||
4429 | } | |||
4430 | ||||
4431 | LLVM_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); | |||
4432 | } | |||
4433 | ||||
4434 | /// Call FilterOutUndesirableDedicatedRegisters again, if necessary, now that | |||
4435 | /// we've done more filtering, as it may be able to find more formulae to | |||
4436 | /// eliminate. | |||
4437 | void LSRInstance::NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters(){ | |||
4438 | if (EstimateSearchSpaceComplexity() >= ComplexityLimit) { | |||
4439 | LLVM_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); | |||
4440 | ||||
4441 | LLVM_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) | |||
4442 | "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); | |||
4443 | ||||
4444 | FilterOutUndesirableDedicatedRegisters(); | |||
4445 | ||||
4446 | LLVM_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); | |||
4447 | } | |||
4448 | } | |||
4449 | ||||
4450 | /// If a LSRUse has multiple formulae with the same ScaledReg and Scale. | |||
4451 | /// Pick the best one and delete the others. | |||
4452 | /// This narrowing heuristic is to keep as many formulae with different | |||
4453 | /// Scale and ScaledReg pair as possible while narrowing the search space. | |||
4454 | /// The benefit is that it is more likely to find out a better solution | |||
4455 | /// from a formulae set with more Scale and ScaledReg variations than | |||
4456 | /// a formulae set with the same Scale and ScaledReg. The picking winner | |||
4457 | /// reg heuristic will often keep the formulae with the same Scale and | |||
4458 | /// ScaledReg and filter others, and we want to avoid that if possible. | |||
4459 | void LSRInstance::NarrowSearchSpaceByFilterFormulaWithSameScaledReg() { | |||
4460 | if (EstimateSearchSpaceComplexity() < ComplexityLimit) | |||
4461 | return; | |||
4462 | ||||
4463 | LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "The search space is too complex.\n" "Narrowing the search space by choosing the best Formula " "from the Formulae with the same Scale and ScaledReg.\n" ; } } while (false) | |||
4464 | 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 choosing the best Formula " "from the Formulae with the same Scale and ScaledReg.\n" ; } } while (false) | |||
4465 | "Narrowing the search space by choosing the best Formula "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "The search space is too complex.\n" "Narrowing the search space by choosing the best Formula " "from the Formulae with the same Scale and ScaledReg.\n" ; } } while (false) | |||
4466 | "from the Formulae with the same Scale and ScaledReg.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "The search space is too complex.\n" "Narrowing the search space by choosing the best Formula " "from the Formulae with the same Scale and ScaledReg.\n" ; } } while (false); | |||
4467 | ||||
4468 | // Map the "Scale * ScaledReg" pair to the best formula of current LSRUse. | |||
4469 | using BestFormulaeTy = DenseMap<std::pair<const SCEV *, int64_t>, size_t>; | |||
4470 | ||||
4471 | BestFormulaeTy BestFormulae; | |||
4472 | #ifndef NDEBUG | |||
4473 | bool ChangedFormulae = false; | |||
4474 | #endif | |||
4475 | DenseSet<const SCEV *> VisitedRegs; | |||
4476 | SmallPtrSet<const SCEV *, 16> Regs; | |||
4477 | ||||
4478 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { | |||
4479 | LSRUse &LU = Uses[LUIdx]; | |||
4480 | LLVM_DEBUG(dbgs() << "Filtering for use "; LU.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Filtering for use "; LU.print (dbgs()); dbgs() << '\n'; } } while (false) | |||
4481 | dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Filtering for use "; LU.print (dbgs()); dbgs() << '\n'; } } while (false); | |||
4482 | ||||
4483 | // Return true if Formula FA is better than Formula FB. | |||
4484 | auto IsBetterThan = [&](Formula &FA, Formula &FB) { | |||
4485 | // First we will try to choose the Formula with fewer new registers. | |||
4486 | // For a register used by current Formula, the more the register is | |||
4487 | // shared among LSRUses, the less we increase the register number | |||
4488 | // counter of the formula. | |||
4489 | size_t FARegNum = 0; | |||
4490 | for (const SCEV *Reg : FA.BaseRegs) { | |||
4491 | const SmallBitVector &UsedByIndices = RegUses.getUsedByIndices(Reg); | |||
4492 | FARegNum += (NumUses - UsedByIndices.count() + 1); | |||
4493 | } | |||
4494 | size_t FBRegNum = 0; | |||
4495 | for (const SCEV *Reg : FB.BaseRegs) { | |||
4496 | const SmallBitVector &UsedByIndices = RegUses.getUsedByIndices(Reg); | |||
4497 | FBRegNum += (NumUses - UsedByIndices.count() + 1); | |||
4498 | } | |||
4499 | if (FARegNum != FBRegNum) | |||
4500 | return FARegNum < FBRegNum; | |||
4501 | ||||
4502 | // If the new register numbers are the same, choose the Formula with | |||
4503 | // less Cost. | |||
4504 | Cost CostFA, CostFB; | |||
4505 | Regs.clear(); | |||
4506 | CostFA.RateFormula(TTI, FA, Regs, VisitedRegs, L, SE, DT, LU); | |||
4507 | Regs.clear(); | |||
4508 | CostFB.RateFormula(TTI, FB, Regs, VisitedRegs, L, SE, DT, LU); | |||
4509 | return CostFA.isLess(CostFB, TTI); | |||
4510 | }; | |||
4511 | ||||
4512 | bool Any = false; | |||
4513 | for (size_t FIdx = 0, NumForms = LU.Formulae.size(); FIdx != NumForms; | |||
4514 | ++FIdx) { | |||
4515 | Formula &F = LU.Formulae[FIdx]; | |||
4516 | if (!F.ScaledReg) | |||
4517 | continue; | |||
4518 | auto P = BestFormulae.insert({{F.ScaledReg, F.Scale}, FIdx}); | |||
4519 | if (P.second) | |||
4520 | continue; | |||
4521 | ||||
4522 | Formula &Best = LU.Formulae[P.first->second]; | |||
4523 | if (IsBetterThan(F, Best)) | |||
4524 | std::swap(F, Best); | |||
4525 | LLVM_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) | |||
4526 | 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) | |||
4527 | " in favor of formula ";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) | |||
4528 | Best.print(dbgs()); 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); | |||
4529 | #ifndef NDEBUG | |||
4530 | ChangedFormulae = true; | |||
4531 | #endif | |||
4532 | LU.DeleteFormula(F); | |||
4533 | --FIdx; | |||
4534 | --NumForms; | |||
4535 | Any = true; | |||
4536 | } | |||
4537 | if (Any) | |||
4538 | LU.RecomputeRegs(LUIdx, RegUses); | |||
4539 | ||||
4540 | // Reset this to prepare for the next use. | |||
4541 | BestFormulae.clear(); | |||
4542 | } | |||
4543 | ||||
4544 | LLVM_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) | |||
4545 | 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) | |||
4546 | "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) | |||
4547 | 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) | |||
4548 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n" "After filtering out undesirable candidates:\n"; print_uses( dbgs()); }; } } while (false); | |||
4549 | } | |||
4550 | ||||
4551 | /// The function delete formulas with high registers number expectation. | |||
4552 | /// Assuming we don't know the value of each formula (already delete | |||
4553 | /// all inefficient), generate probability of not selecting for each | |||
4554 | /// register. | |||
4555 | /// For example, | |||
4556 | /// Use1: | |||
4557 | /// reg(a) + reg({0,+,1}) | |||
4558 | /// reg(a) + reg({-1,+,1}) + 1 | |||
4559 | /// reg({a,+,1}) | |||
4560 | /// Use2: | |||
4561 | /// reg(b) + reg({0,+,1}) | |||
4562 | /// reg(b) + reg({-1,+,1}) + 1 | |||
4563 | /// reg({b,+,1}) | |||
4564 | /// Use3: | |||
4565 | /// reg(c) + reg(b) + reg({0,+,1}) | |||
4566 | /// reg(c) + reg({b,+,1}) | |||
4567 | /// | |||
4568 | /// Probability of not selecting | |||
4569 | /// Use1 Use2 Use3 | |||
4570 | /// reg(a) (1/3) * 1 * 1 | |||
4571 | /// reg(b) 1 * (1/3) * (1/2) | |||
4572 | /// reg({0,+,1}) (2/3) * (2/3) * (1/2) | |||
4573 | /// reg({-1,+,1}) (2/3) * (2/3) * 1 | |||
4574 | /// reg({a,+,1}) (2/3) * 1 * 1 | |||
4575 | /// reg({b,+,1}) 1 * (2/3) * (2/3) | |||
4576 | /// reg(c) 1 * 1 * 0 | |||
4577 | /// | |||
4578 | /// Now count registers number mathematical expectation for each formula: | |||
4579 | /// Note that for each use we exclude probability if not selecting for the use. | |||
4580 | /// For example for Use1 probability for reg(a) would be just 1 * 1 (excluding | |||
4581 | /// probabilty 1/3 of not selecting for Use1). | |||
4582 | /// Use1: | |||
4583 | /// reg(a) + reg({0,+,1}) 1 + 1/3 -- to be deleted | |||
4584 | /// reg(a) + reg({-1,+,1}) + 1 1 + 4/9 -- to be deleted | |||
4585 | /// reg({a,+,1}) 1 | |||
4586 | /// Use2: | |||
4587 | /// reg(b) + reg({0,+,1}) 1/2 + 1/3 -- to be deleted | |||
4588 | /// reg(b) + reg({-1,+,1}) + 1 1/2 + 2/3 -- to be deleted | |||
4589 | /// reg({b,+,1}) 2/3 | |||
4590 | /// Use3: | |||
4591 | /// reg(c) + reg(b) + reg({0,+,1}) 1 + 1/3 + 4/9 -- to be deleted | |||
4592 | /// reg(c) + reg({b,+,1}) 1 + 2/3 | |||
4593 | void LSRInstance::NarrowSearchSpaceByDeletingCostlyFormulas() { | |||
4594 | if (EstimateSearchSpaceComplexity() < ComplexityLimit) | |||
4595 | return; | |||
4596 | // Ok, we have too many of formulae on our hands to conveniently handle. | |||
4597 | // Use a rough heuristic to thin out the list. | |||
4598 | ||||
4599 | // Set of Regs wich will be 100% used in final solution. | |||
4600 | // Used in each formula of a solution (in example above this is reg(c)). | |||
4601 | // We can skip them in calculations. | |||
4602 | SmallPtrSet<const SCEV *, 4> UniqRegs; | |||
4603 | LLVM_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); | |||
4604 | ||||
4605 | // Map each register to probability of not selecting | |||
4606 | DenseMap <const SCEV *, float> RegNumMap; | |||
4607 | for (const SCEV *Reg : RegUses) { | |||
4608 | if (UniqRegs.count(Reg)) | |||
4609 | continue; | |||
4610 | float PNotSel = 1; | |||
4611 | for (const LSRUse &LU : Uses) { | |||
4612 | if (!LU.Regs.count(Reg)) | |||
4613 | continue; | |||
4614 | float P = LU.getNotSelectedProbability(Reg); | |||
4615 | if (P != 0.0) | |||
4616 | PNotSel *= P; | |||
4617 | else | |||
4618 | UniqRegs.insert(Reg); | |||
4619 | } | |||
4620 | RegNumMap.insert(std::make_pair(Reg, PNotSel)); | |||
4621 | } | |||
4622 | ||||
4623 | LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Narrowing the search space by deleting costly formulas\n" ; } } while (false) | |||
4624 | dbgs() << "Narrowing the search space by deleting costly formulas\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "Narrowing the search space by deleting costly formulas\n" ; } } while (false); | |||
4625 | ||||
4626 | // Delete formulas where registers number expectation is high. | |||
4627 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { | |||
4628 | LSRUse &LU = Uses[LUIdx]; | |||
4629 | // If nothing to delete - continue. | |||
4630 | if (LU.Formulae.size() < 2) | |||
4631 | continue; | |||
4632 | // This is temporary solution to test performance. Float should be | |||
4633 | // replaced with round independent type (based on integers) to avoid | |||
4634 | // different results for different target builds. | |||
4635 | float FMinRegNum = LU.Formulae[0].getNumRegs(); | |||
4636 | float FMinARegNum = LU.Formulae[0].getNumRegs(); | |||
4637 | size_t MinIdx = 0; | |||
4638 | for (size_t i = 0, e = LU.Formulae.size(); i != e; ++i) { | |||
4639 | Formula &F = LU.Formulae[i]; | |||
4640 | float FRegNum = 0; | |||
4641 | float FARegNum = 0; | |||
4642 | for (const SCEV *BaseReg : F.BaseRegs) { | |||
4643 | if (UniqRegs.count(BaseReg)) | |||
4644 | continue; | |||
4645 | FRegNum += RegNumMap[BaseReg] / LU.getNotSelectedProbability(BaseReg); | |||
4646 | if (isa<SCEVAddRecExpr>(BaseReg)) | |||
4647 | FARegNum += | |||
4648 | RegNumMap[BaseReg] / LU.getNotSelectedProbability(BaseReg); | |||
4649 | } | |||
4650 | if (const SCEV *ScaledReg = F.ScaledReg) { | |||
4651 | if (!UniqRegs.count(ScaledReg)) { | |||
4652 | FRegNum += | |||
4653 | RegNumMap[ScaledReg] / LU.getNotSelectedProbability(ScaledReg); | |||
4654 | if (isa<SCEVAddRecExpr>(ScaledReg)) | |||
4655 | FARegNum += | |||
4656 | RegNumMap[ScaledReg] / LU.getNotSelectedProbability(ScaledReg); | |||
4657 | } | |||
4658 | } | |||
4659 | if (FMinRegNum > FRegNum || | |||
4660 | (FMinRegNum == FRegNum && FMinARegNum > FARegNum)) { | |||
4661 | FMinRegNum = FRegNum; | |||
4662 | FMinARegNum = FARegNum; | |||
4663 | MinIdx = i; | |||
4664 | } | |||
4665 | } | |||
4666 | LLVM_DEBUG(dbgs() << " The formula "; LU.Formulae[MinIdx].print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " The formula "; LU.Formulae [MinIdx].print(dbgs()); dbgs() << " with min reg num " << FMinRegNum << '\n'; } } while (false) | |||
4667 | dbgs() << " with min reg num " << FMinRegNum << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " The formula "; LU.Formulae [MinIdx].print(dbgs()); dbgs() << " with min reg num " << FMinRegNum << '\n'; } } while (false); | |||
4668 | if (MinIdx != 0) | |||
4669 | std::swap(LU.Formulae[MinIdx], LU.Formulae[0]); | |||
4670 | while (LU.Formulae.size() != 1) { | |||
4671 | LLVM_DEBUG(dbgs() << " Deleting "; LU.Formulae.back().print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Deleting "; LU.Formulae .back().print(dbgs()); dbgs() << '\n'; } } while (false ) | |||
4672 | dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Deleting "; LU.Formulae .back().print(dbgs()); dbgs() << '\n'; } } while (false ); | |||
4673 | LU.Formulae.pop_back(); | |||
4674 | } | |||
4675 | LU.RecomputeRegs(LUIdx, RegUses); | |||
4676 | assert(LU.Formulae.size() == 1 && "Should be exactly 1 min regs formula")(static_cast <bool> (LU.Formulae.size() == 1 && "Should be exactly 1 min regs formula") ? void (0) : __assert_fail ("LU.Formulae.size() == 1 && \"Should be exactly 1 min regs formula\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4676, __extension__ __PRETTY_FUNCTION__)); | |||
4677 | Formula &F = LU.Formulae[0]; | |||
4678 | LLVM_DEBUG(dbgs() << " Leaving only "; F.print(dbgs()); dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << " Leaving only "; F.print (dbgs()); dbgs() << '\n'; } } while (false); | |||
4679 | // When we choose the formula, the regs become unique. | |||
4680 | UniqRegs.insert(F.BaseRegs.begin(), F.BaseRegs.end()); | |||
4681 | if (F.ScaledReg) | |||
4682 | UniqRegs.insert(F.ScaledReg); | |||
4683 | } | |||
4684 | LLVM_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); | |||
4685 | } | |||
4686 | ||||
4687 | /// Pick a register which seems likely to be profitable, and then in any use | |||
4688 | /// which has any reference to that register, delete all formulae which do not | |||
4689 | /// reference that register. | |||
4690 | void LSRInstance::NarrowSearchSpaceByPickingWinnerRegs() { | |||
4691 | // With all other options exhausted, loop until the system is simple | |||
4692 | // enough to handle. | |||
4693 | SmallPtrSet<const SCEV *, 4> Taken; | |||
4694 | while (EstimateSearchSpaceComplexity() >= ComplexityLimit) { | |||
4695 | // Ok, we have too many of formulae on our hands to conveniently handle. | |||
4696 | // Use a rough heuristic to thin out the list. | |||
4697 | LLVM_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); | |||
4698 | ||||
4699 | // Pick the register which is used by the most LSRUses, which is likely | |||
4700 | // to be a good reuse register candidate. | |||
4701 | const SCEV *Best = nullptr; | |||
4702 | unsigned BestNum = 0; | |||
4703 | for (const SCEV *Reg : RegUses) { | |||
4704 | if (Taken.count(Reg)) | |||
4705 | continue; | |||
4706 | if (!Best) { | |||
4707 | Best = Reg; | |||
4708 | BestNum = RegUses.getUsedByIndices(Reg).count(); | |||
4709 | } else { | |||
4710 | unsigned Count = RegUses.getUsedByIndices(Reg).count(); | |||
4711 | if (Count > BestNum) { | |||
4712 | Best = Reg; | |||
4713 | BestNum = Count; | |||
4714 | } | |||
4715 | } | |||
4716 | } | |||
4717 | ||||
4718 | LLVM_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) | |||
4719 | << " 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); | |||
4720 | Taken.insert(Best); | |||
4721 | ||||
4722 | // In any use with formulae which references this register, delete formulae | |||
4723 | // which don't reference it. | |||
4724 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { | |||
4725 | LSRUse &LU = Uses[LUIdx]; | |||
4726 | if (!LU.Regs.count(Best)) continue; | |||
4727 | ||||
4728 | bool Any = false; | |||
4729 | for (size_t i = 0, e = LU.Formulae.size(); i != e; ++i) { | |||
4730 | Formula &F = LU.Formulae[i]; | |||
4731 | if (!F.referencesReg(Best)) { | |||
4732 | LLVM_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); | |||
4733 | LU.DeleteFormula(F); | |||
4734 | --e; | |||
4735 | --i; | |||
4736 | Any = true; | |||
4737 | assert(e != 0 && "Use has no formulae left! Is Regs inconsistent?")(static_cast <bool> (e != 0 && "Use has no formulae left! Is Regs inconsistent?" ) ? void (0) : __assert_fail ("e != 0 && \"Use has no formulae left! Is Regs inconsistent?\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4737, __extension__ __PRETTY_FUNCTION__)); | |||
4738 | continue; | |||
4739 | } | |||
4740 | } | |||
4741 | ||||
4742 | if (Any) | |||
4743 | LU.RecomputeRegs(LUIdx, RegUses); | |||
4744 | } | |||
4745 | ||||
4746 | LLVM_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); | |||
4747 | } | |||
4748 | } | |||
4749 | ||||
4750 | /// If there are an extraordinary number of formulae to choose from, use some | |||
4751 | /// rough heuristics to prune down the number of formulae. This keeps the main | |||
4752 | /// solver from taking an extraordinary amount of time in some worst-case | |||
4753 | /// scenarios. | |||
4754 | void LSRInstance::NarrowSearchSpaceUsingHeuristics() { | |||
4755 | NarrowSearchSpaceByDetectingSupersets(); | |||
4756 | NarrowSearchSpaceByCollapsingUnrolledCode(); | |||
4757 | NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters(); | |||
4758 | if (FilterSameScaledReg) | |||
4759 | NarrowSearchSpaceByFilterFormulaWithSameScaledReg(); | |||
4760 | if (LSRExpNarrow) | |||
4761 | NarrowSearchSpaceByDeletingCostlyFormulas(); | |||
4762 | else | |||
4763 | NarrowSearchSpaceByPickingWinnerRegs(); | |||
4764 | } | |||
4765 | ||||
4766 | /// This is the recursive solver. | |||
4767 | void LSRInstance::SolveRecurse(SmallVectorImpl<const Formula *> &Solution, | |||
4768 | Cost &SolutionCost, | |||
4769 | SmallVectorImpl<const Formula *> &Workspace, | |||
4770 | const Cost &CurCost, | |||
4771 | const SmallPtrSet<const SCEV *, 16> &CurRegs, | |||
4772 | DenseSet<const SCEV *> &VisitedRegs) const { | |||
4773 | // Some ideas: | |||
4774 | // - prune more: | |||
4775 | // - use more aggressive filtering | |||
4776 | // - sort the formula so that the most profitable solutions are found first | |||
4777 | // - sort the uses too | |||
4778 | // - search faster: | |||
4779 | // - don't compute a cost, and then compare. compare while computing a cost | |||
4780 | // and bail early. | |||
4781 | // - track register sets with SmallBitVector | |||
4782 | ||||
4783 | const LSRUse &LU = Uses[Workspace.size()]; | |||
4784 | ||||
4785 | // If this use references any register that's already a part of the | |||
4786 | // in-progress solution, consider it a requirement that a formula must | |||
4787 | // reference that register in order to be considered. This prunes out | |||
4788 | // unprofitable searching. | |||
4789 | SmallSetVector<const SCEV *, 4> ReqRegs; | |||
4790 | for (const SCEV *S : CurRegs) | |||
4791 | if (LU.Regs.count(S)) | |||
4792 | ReqRegs.insert(S); | |||
4793 | ||||
4794 | SmallPtrSet<const SCEV *, 16> NewRegs; | |||
4795 | Cost NewCost; | |||
4796 | for (const Formula &F : LU.Formulae) { | |||
4797 | // Ignore formulae which may not be ideal in terms of register reuse of | |||
4798 | // ReqRegs. The formula should use all required registers before | |||
4799 | // introducing new ones. | |||
4800 | int NumReqRegsToFind = std::min(F.getNumRegs(), ReqRegs.size()); | |||
4801 | for (const SCEV *Reg : ReqRegs) { | |||
4802 | if ((F.ScaledReg && F.ScaledReg == Reg) || | |||
4803 | is_contained(F.BaseRegs, Reg)) { | |||
4804 | --NumReqRegsToFind; | |||
4805 | if (NumReqRegsToFind == 0) | |||
4806 | break; | |||
4807 | } | |||
4808 | } | |||
4809 | if (NumReqRegsToFind != 0) { | |||
4810 | // If none of the formulae satisfied the required registers, then we could | |||
4811 | // clear ReqRegs and try again. Currently, we simply give up in this case. | |||
4812 | continue; | |||
4813 | } | |||
4814 | ||||
4815 | // Evaluate the cost of the current formula. If it's already worse than | |||
4816 | // the current best, prune the search at that point. | |||
4817 | NewCost = CurCost; | |||
4818 | NewRegs = CurRegs; | |||
4819 | NewCost.RateFormula(TTI, F, NewRegs, VisitedRegs, L, SE, DT, LU); | |||
4820 | if (NewCost.isLess(SolutionCost, TTI)) { | |||
4821 | Workspace.push_back(&F); | |||
4822 | if (Workspace.size() != Uses.size()) { | |||
4823 | SolveRecurse(Solution, SolutionCost, Workspace, NewCost, | |||
4824 | NewRegs, VisitedRegs); | |||
4825 | if (F.getNumRegs() == 1 && Workspace.size() == 1) | |||
4826 | VisitedRegs.insert(F.ScaledReg ? F.ScaledReg : F.BaseRegs[0]); | |||
4827 | } else { | |||
4828 | LLVM_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) | |||
4829 | dbgs() << ".\n Regs:"; for (const SCEV *Sdo { 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) | |||
4830 | : NewRegs) 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) | |||
4831 | << ' ' << *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) | |||
4832 | 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); | |||
4833 | ||||
4834 | SolutionCost = NewCost; | |||
4835 | Solution = Workspace; | |||
4836 | } | |||
4837 | Workspace.pop_back(); | |||
4838 | } | |||
4839 | } | |||
4840 | } | |||
4841 | ||||
4842 | /// Choose one formula from each use. Return the results in the given Solution | |||
4843 | /// vector. | |||
4844 | void LSRInstance::Solve(SmallVectorImpl<const Formula *> &Solution) const { | |||
4845 | SmallVector<const Formula *, 8> Workspace; | |||
4846 | Cost SolutionCost; | |||
4847 | SolutionCost.Lose(); | |||
4848 | Cost CurCost; | |||
4849 | SmallPtrSet<const SCEV *, 16> CurRegs; | |||
4850 | DenseSet<const SCEV *> VisitedRegs; | |||
4851 | Workspace.reserve(Uses.size()); | |||
4852 | ||||
4853 | // SolveRecurse does all the work. | |||
4854 | SolveRecurse(Solution, SolutionCost, Workspace, CurCost, | |||
4855 | CurRegs, VisitedRegs); | |||
4856 | if (Solution.empty()) { | |||
4857 | LLVM_DEBUG(dbgs() << "\nNo Satisfactory Solution\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\nNo Satisfactory Solution\n" ; } } while (false); | |||
4858 | return; | |||
4859 | } | |||
4860 | ||||
4861 | // Ok, we've now made all our decisions. | |||
4862 | LLVM_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 ) | |||
4863 | "The chosen solution requires ";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 ) | |||
4864 | SolutionCost.print(dbgs()); 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 ) | |||
4865 | 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 ) | |||
4866 | 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 ) | |||
4867 | 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 ) | |||
4868 | 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 ) | |||
4869 | " ";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 ) | |||
4870 | 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 ) | |||
4871 | 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 ) | |||
4872 | })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 ); | |||
4873 | ||||
4874 | assert(Solution.size() == Uses.size() && "Malformed solution!")(static_cast <bool> (Solution.size() == Uses.size() && "Malformed solution!") ? void (0) : __assert_fail ("Solution.size() == Uses.size() && \"Malformed solution!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4874, __extension__ __PRETTY_FUNCTION__)); | |||
4875 | } | |||
4876 | ||||
4877 | /// Helper for AdjustInsertPositionForExpand. Climb up the dominator tree far as | |||
4878 | /// we can go while still being dominated by the input positions. This helps | |||
4879 | /// canonicalize the insert position, which encourages sharing. | |||
4880 | BasicBlock::iterator | |||
4881 | LSRInstance::HoistInsertPosition(BasicBlock::iterator IP, | |||
4882 | const SmallVectorImpl<Instruction *> &Inputs) | |||
4883 | const { | |||
4884 | Instruction *Tentative = &*IP; | |||
4885 | while (true) { | |||
4886 | bool AllDominate = true; | |||
4887 | Instruction *BetterPos = nullptr; | |||
4888 | // Don't bother attempting to insert before a catchswitch, their basic block | |||
4889 | // cannot have other non-PHI instructions. | |||
4890 | if (isa<CatchSwitchInst>(Tentative)) | |||
4891 | return IP; | |||
4892 | ||||
4893 | for (Instruction *Inst : Inputs) { | |||
4894 | if (Inst == Tentative || !DT.dominates(Inst, Tentative)) { | |||
4895 | AllDominate = false; | |||
4896 | break; | |||
4897 | } | |||
4898 | // Attempt to find an insert position in the middle of the block, | |||
4899 | // instead of at the end, so that it can be used for other expansions. | |||
4900 | if (Tentative->getParent() == Inst->getParent() && | |||
4901 | (!BetterPos || !DT.dominates(Inst, BetterPos))) | |||
4902 | BetterPos = &*std::next(BasicBlock::iterator(Inst)); | |||
4903 | } | |||
4904 | if (!AllDominate) | |||
4905 | break; | |||
4906 | if (BetterPos) | |||
4907 | IP = BetterPos->getIterator(); | |||
4908 | else | |||
4909 | IP = Tentative->getIterator(); | |||
4910 | ||||
4911 | const Loop *IPLoop = LI.getLoopFor(IP->getParent()); | |||
4912 | unsigned IPLoopDepth = IPLoop ? IPLoop->getLoopDepth() : 0; | |||
4913 | ||||
4914 | BasicBlock *IDom; | |||
4915 | for (DomTreeNode *Rung = DT.getNode(IP->getParent()); ; ) { | |||
4916 | if (!Rung) return IP; | |||
4917 | Rung = Rung->getIDom(); | |||
4918 | if (!Rung) return IP; | |||
4919 | IDom = Rung->getBlock(); | |||
4920 | ||||
4921 | // Don't climb into a loop though. | |||
4922 | const Loop *IDomLoop = LI.getLoopFor(IDom); | |||
4923 | unsigned IDomDepth = IDomLoop ? IDomLoop->getLoopDepth() : 0; | |||
4924 | if (IDomDepth <= IPLoopDepth && | |||
4925 | (IDomDepth != IPLoopDepth || IDomLoop == IPLoop)) | |||
4926 | break; | |||
4927 | } | |||
4928 | ||||
4929 | Tentative = IDom->getTerminator(); | |||
4930 | } | |||
4931 | ||||
4932 | return IP; | |||
4933 | } | |||
4934 | ||||
4935 | /// Determine an input position which will be dominated by the operands and | |||
4936 | /// which will dominate the result. | |||
4937 | BasicBlock::iterator | |||
4938 | LSRInstance::AdjustInsertPositionForExpand(BasicBlock::iterator LowestIP, | |||
4939 | const LSRFixup &LF, | |||
4940 | const LSRUse &LU, | |||
4941 | SCEVExpander &Rewriter) const { | |||
4942 | // Collect some instructions which must be dominated by the | |||
4943 | // expanding replacement. These must be dominated by any operands that | |||
4944 | // will be required in the expansion. | |||
4945 | SmallVector<Instruction *, 4> Inputs; | |||
4946 | if (Instruction *I = dyn_cast<Instruction>(LF.OperandValToReplace)) | |||
4947 | Inputs.push_back(I); | |||
4948 | if (LU.Kind == LSRUse::ICmpZero) | |||
4949 | if (Instruction *I = | |||
4950 | dyn_cast<Instruction>(cast<ICmpInst>(LF.UserInst)->getOperand(1))) | |||
4951 | Inputs.push_back(I); | |||
4952 | if (LF.PostIncLoops.count(L)) { | |||
4953 | if (LF.isUseFullyOutsideLoop(L)) | |||
4954 | Inputs.push_back(L->getLoopLatch()->getTerminator()); | |||
4955 | else | |||
4956 | Inputs.push_back(IVIncInsertPos); | |||
4957 | } | |||
4958 | // The expansion must also be dominated by the increment positions of any | |||
4959 | // loops it for which it is using post-inc mode. | |||
4960 | for (const Loop *PIL : LF.PostIncLoops) { | |||
4961 | if (PIL == L) continue; | |||
4962 | ||||
4963 | // Be dominated by the loop exit. | |||
4964 | SmallVector<BasicBlock *, 4> ExitingBlocks; | |||
4965 | PIL->getExitingBlocks(ExitingBlocks); | |||
4966 | if (!ExitingBlocks.empty()) { | |||
4967 | BasicBlock *BB = ExitingBlocks[0]; | |||
4968 | for (unsigned i = 1, e = ExitingBlocks.size(); i != e; ++i) | |||
4969 | BB = DT.findNearestCommonDominator(BB, ExitingBlocks[i]); | |||
4970 | Inputs.push_back(BB->getTerminator()); | |||
4971 | } | |||
4972 | } | |||
4973 | ||||
4974 | assert(!isa<PHINode>(LowestIP) && !LowestIP->isEHPad()(static_cast <bool> (!isa<PHINode>(LowestIP) && !LowestIP->isEHPad() && !isa<DbgInfoIntrinsic> (LowestIP) && "Insertion point must be a normal instruction" ) ? void (0) : __assert_fail ("!isa<PHINode>(LowestIP) && !LowestIP->isEHPad() && !isa<DbgInfoIntrinsic>(LowestIP) && \"Insertion point must be a normal instruction\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4976, __extension__ __PRETTY_FUNCTION__)) | |||
4975 | && !isa<DbgInfoIntrinsic>(LowestIP) &&(static_cast <bool> (!isa<PHINode>(LowestIP) && !LowestIP->isEHPad() && !isa<DbgInfoIntrinsic> (LowestIP) && "Insertion point must be a normal instruction" ) ? void (0) : __assert_fail ("!isa<PHINode>(LowestIP) && !LowestIP->isEHPad() && !isa<DbgInfoIntrinsic>(LowestIP) && \"Insertion point must be a normal instruction\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4976, __extension__ __PRETTY_FUNCTION__)) | |||
4976 | "Insertion point must be a normal instruction")(static_cast <bool> (!isa<PHINode>(LowestIP) && !LowestIP->isEHPad() && !isa<DbgInfoIntrinsic> (LowestIP) && "Insertion point must be a normal instruction" ) ? void (0) : __assert_fail ("!isa<PHINode>(LowestIP) && !LowestIP->isEHPad() && !isa<DbgInfoIntrinsic>(LowestIP) && \"Insertion point must be a normal instruction\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 4976, __extension__ __PRETTY_FUNCTION__)); | |||
4977 | ||||
4978 | // Then, climb up the immediate dominator tree as far as we can go while | |||
4979 | // still being dominated by the input positions. | |||
4980 | BasicBlock::iterator IP = HoistInsertPosition(LowestIP, Inputs); | |||
4981 | ||||
4982 | // Don't insert instructions before PHI nodes. | |||
4983 | while (isa<PHINode>(IP)) ++IP; | |||
4984 | ||||
4985 | // Ignore landingpad instructions. | |||
4986 | while (IP->isEHPad()) ++IP; | |||
4987 | ||||
4988 | // Ignore debug intrinsics. | |||
4989 | while (isa<DbgInfoIntrinsic>(IP)) ++IP; | |||
4990 | ||||
4991 | // Set IP below instructions recently inserted by SCEVExpander. This keeps the | |||
4992 | // IP consistent across expansions and allows the previously inserted | |||
4993 | // instructions to be reused by subsequent expansion. | |||
4994 | while (Rewriter.isInsertedInstruction(&*IP) && IP != LowestIP) | |||
4995 | ++IP; | |||
4996 | ||||
4997 | return IP; | |||
4998 | } | |||
4999 | ||||
5000 | /// Emit instructions for the leading candidate expression for this LSRUse (this | |||
5001 | /// is called "expanding"). | |||
5002 | Value *LSRInstance::Expand(const LSRUse &LU, const LSRFixup &LF, | |||
5003 | const Formula &F, BasicBlock::iterator IP, | |||
5004 | SCEVExpander &Rewriter, | |||
5005 | SmallVectorImpl<WeakTrackingVH> &DeadInsts) const { | |||
5006 | if (LU.RigidFormula) | |||
5007 | return LF.OperandValToReplace; | |||
5008 | ||||
5009 | // Determine an input position which will be dominated by the operands and | |||
5010 | // which will dominate the result. | |||
5011 | IP = AdjustInsertPositionForExpand(IP, LF, LU, Rewriter); | |||
5012 | Rewriter.setInsertPoint(&*IP); | |||
5013 | ||||
5014 | // Inform the Rewriter if we have a post-increment use, so that it can | |||
5015 | // perform an advantageous expansion. | |||
5016 | Rewriter.setPostInc(LF.PostIncLoops); | |||
5017 | ||||
5018 | // This is the type that the user actually needs. | |||
5019 | Type *OpTy = LF.OperandValToReplace->getType(); | |||
5020 | // This will be the type that we'll initially expand to. | |||
5021 | Type *Ty = F.getType(); | |||
5022 | if (!Ty) | |||
5023 | // No type known; just expand directly to the ultimate type. | |||
5024 | Ty = OpTy; | |||
5025 | else if (SE.getEffectiveSCEVType(Ty) == SE.getEffectiveSCEVType(OpTy)) | |||
5026 | // Expand directly to the ultimate type if it's the right size. | |||
5027 | Ty = OpTy; | |||
5028 | // This is the type to do integer arithmetic in. | |||
5029 | Type *IntTy = SE.getEffectiveSCEVType(Ty); | |||
5030 | ||||
5031 | // Build up a list of operands to add together to form the full base. | |||
5032 | SmallVector<const SCEV *, 8> Ops; | |||
5033 | ||||
5034 | // Expand the BaseRegs portion. | |||
5035 | for (const SCEV *Reg : F.BaseRegs) { | |||
5036 | assert(!Reg->isZero() && "Zero allocated in a base register!")(static_cast <bool> (!Reg->isZero() && "Zero allocated in a base register!" ) ? void (0) : __assert_fail ("!Reg->isZero() && \"Zero allocated in a base register!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 5036, __extension__ __PRETTY_FUNCTION__)); | |||
5037 | ||||
5038 | // If we're expanding for a post-inc user, make the post-inc adjustment. | |||
5039 | Reg = denormalizeForPostIncUse(Reg, LF.PostIncLoops, SE); | |||
5040 | Ops.push_back(SE.getUnknown(Rewriter.expandCodeFor(Reg, nullptr))); | |||
5041 | } | |||
5042 | ||||
5043 | // Expand the ScaledReg portion. | |||
5044 | Value *ICmpScaledV = nullptr; | |||
5045 | if (F.Scale != 0) { | |||
5046 | const SCEV *ScaledS = F.ScaledReg; | |||
5047 | ||||
5048 | // If we're expanding for a post-inc user, make the post-inc adjustment. | |||
5049 | PostIncLoopSet &Loops = const_cast<PostIncLoopSet &>(LF.PostIncLoops); | |||
5050 | ScaledS = denormalizeForPostIncUse(ScaledS, Loops, SE); | |||
5051 | ||||
5052 | if (LU.Kind == LSRUse::ICmpZero) { | |||
5053 | // Expand ScaleReg as if it was part of the base regs. | |||
5054 | if (F.Scale == 1) | |||
5055 | Ops.push_back( | |||
5056 | SE.getUnknown(Rewriter.expandCodeFor(ScaledS, nullptr))); | |||
5057 | else { | |||
5058 | // An interesting way of "folding" with an icmp is to use a negated | |||
5059 | // scale, which we'll implement by inserting it into the other operand | |||
5060 | // of the icmp. | |||
5061 | assert(F.Scale == -1 &&(static_cast <bool> (F.Scale == -1 && "The only scale supported by ICmpZero uses is -1!" ) ? void (0) : __assert_fail ("F.Scale == -1 && \"The only scale supported by ICmpZero uses is -1!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 5062, __extension__ __PRETTY_FUNCTION__)) | |||
5062 | "The only scale supported by ICmpZero uses is -1!")(static_cast <bool> (F.Scale == -1 && "The only scale supported by ICmpZero uses is -1!" ) ? void (0) : __assert_fail ("F.Scale == -1 && \"The only scale supported by ICmpZero uses is -1!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 5062, __extension__ __PRETTY_FUNCTION__)); | |||
5063 | ICmpScaledV = Rewriter.expandCodeFor(ScaledS, nullptr); | |||
5064 | } | |||
5065 | } else { | |||
5066 | // Otherwise just expand the scaled register and an explicit scale, | |||
5067 | // which is expected to be matched as part of the address. | |||
5068 | ||||
5069 | // Flush the operand list to suppress SCEVExpander hoisting address modes. | |||
5070 | // Unless the addressing mode will not be folded. | |||
5071 | if (!Ops.empty() && LU.Kind == LSRUse::Address && | |||
5072 | isAMCompletelyFolded(TTI, LU, F)) { | |||
5073 | Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), nullptr); | |||
5074 | Ops.clear(); | |||
5075 | Ops.push_back(SE.getUnknown(FullV)); | |||
5076 | } | |||
5077 | ScaledS = SE.getUnknown(Rewriter.expandCodeFor(ScaledS, nullptr)); | |||
5078 | if (F.Scale != 1) | |||
5079 | ScaledS = | |||
5080 | SE.getMulExpr(ScaledS, SE.getConstant(ScaledS->getType(), F.Scale)); | |||
5081 | Ops.push_back(ScaledS); | |||
5082 | } | |||
5083 | } | |||
5084 | ||||
5085 | // Expand the GV portion. | |||
5086 | if (F.BaseGV) { | |||
5087 | // Flush the operand list to suppress SCEVExpander hoisting. | |||
5088 | if (!Ops.empty()) { | |||
5089 | Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty); | |||
5090 | Ops.clear(); | |||
5091 | Ops.push_back(SE.getUnknown(FullV)); | |||
5092 | } | |||
5093 | Ops.push_back(SE.getUnknown(F.BaseGV)); | |||
5094 | } | |||
5095 | ||||
5096 | // Flush the operand list to suppress SCEVExpander hoisting of both folded and | |||
5097 | // unfolded offsets. LSR assumes they both live next to their uses. | |||
5098 | if (!Ops.empty()) { | |||
5099 | Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty); | |||
5100 | Ops.clear(); | |||
5101 | Ops.push_back(SE.getUnknown(FullV)); | |||
5102 | } | |||
5103 | ||||
5104 | // Expand the immediate portion. | |||
5105 | int64_t Offset = (uint64_t)F.BaseOffset + LF.Offset; | |||
5106 | if (Offset != 0) { | |||
5107 | if (LU.Kind == LSRUse::ICmpZero) { | |||
5108 | // The other interesting way of "folding" with an ICmpZero is to use a | |||
5109 | // negated immediate. | |||
5110 | if (!ICmpScaledV) | |||
5111 | ICmpScaledV = ConstantInt::get(IntTy, -(uint64_t)Offset); | |||
5112 | else { | |||
5113 | Ops.push_back(SE.getUnknown(ICmpScaledV)); | |||
5114 | ICmpScaledV = ConstantInt::get(IntTy, Offset); | |||
5115 | } | |||
5116 | } else { | |||
5117 | // Just add the immediate values. These again are expected to be matched | |||
5118 | // as part of the address. | |||
5119 | Ops.push_back(SE.getUnknown(ConstantInt::getSigned(IntTy, Offset))); | |||
5120 | } | |||
5121 | } | |||
5122 | ||||
5123 | // Expand the unfolded offset portion. | |||
5124 | int64_t UnfoldedOffset = F.UnfoldedOffset; | |||
5125 | if (UnfoldedOffset != 0) { | |||
5126 | // Just add the immediate values. | |||
5127 | Ops.push_back(SE.getUnknown(ConstantInt::getSigned(IntTy, | |||
5128 | UnfoldedOffset))); | |||
5129 | } | |||
5130 | ||||
5131 | // Emit instructions summing all the operands. | |||
5132 | const SCEV *FullS = Ops.empty() ? | |||
5133 | SE.getConstant(IntTy, 0) : | |||
5134 | SE.getAddExpr(Ops); | |||
5135 | Value *FullV = Rewriter.expandCodeFor(FullS, Ty); | |||
5136 | ||||
5137 | // We're done expanding now, so reset the rewriter. | |||
5138 | Rewriter.clearPostInc(); | |||
5139 | ||||
5140 | // An ICmpZero Formula represents an ICmp which we're handling as a | |||
5141 | // comparison against zero. Now that we've expanded an expression for that | |||
5142 | // form, update the ICmp's other operand. | |||
5143 | if (LU.Kind == LSRUse::ICmpZero) { | |||
5144 | ICmpInst *CI = cast<ICmpInst>(LF.UserInst); | |||
5145 | DeadInsts.emplace_back(CI->getOperand(1)); | |||
5146 | assert(!F.BaseGV && "ICmp does not support folding a global value and "(static_cast <bool> (!F.BaseGV && "ICmp does not support folding a global value and " "a scale at the same time!") ? void (0) : __assert_fail ("!F.BaseGV && \"ICmp does not support folding a global value and \" \"a scale at the same time!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 5147, __extension__ __PRETTY_FUNCTION__)) | |||
5147 | "a scale at the same time!")(static_cast <bool> (!F.BaseGV && "ICmp does not support folding a global value and " "a scale at the same time!") ? void (0) : __assert_fail ("!F.BaseGV && \"ICmp does not support folding a global value and \" \"a scale at the same time!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 5147, __extension__ __PRETTY_FUNCTION__)); | |||
5148 | if (F.Scale == -1) { | |||
5149 | if (ICmpScaledV->getType() != OpTy) { | |||
5150 | Instruction *Cast = | |||
5151 | CastInst::Create(CastInst::getCastOpcode(ICmpScaledV, false, | |||
5152 | OpTy, false), | |||
5153 | ICmpScaledV, OpTy, "tmp", CI); | |||
5154 | ICmpScaledV = Cast; | |||
5155 | } | |||
5156 | CI->setOperand(1, ICmpScaledV); | |||
5157 | } else { | |||
5158 | // A scale of 1 means that the scale has been expanded as part of the | |||
5159 | // base regs. | |||
5160 | assert((F.Scale == 0 || F.Scale == 1) &&(static_cast <bool> ((F.Scale == 0 || F.Scale == 1) && "ICmp does not support folding a global value and " "a scale at the same time!" ) ? 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!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 5162, __extension__ __PRETTY_FUNCTION__)) | |||
5161 | "ICmp does not support folding a global value and "(static_cast <bool> ((F.Scale == 0 || F.Scale == 1) && "ICmp does not support folding a global value and " "a scale at the same time!" ) ? 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!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 5162, __extension__ __PRETTY_FUNCTION__)) | |||
5162 | "a scale at the same time!")(static_cast <bool> ((F.Scale == 0 || F.Scale == 1) && "ICmp does not support folding a global value and " "a scale at the same time!" ) ? 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!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 5162, __extension__ __PRETTY_FUNCTION__)); | |||
5163 | Constant *C = ConstantInt::getSigned(SE.getEffectiveSCEVType(OpTy), | |||
5164 | -(uint64_t)Offset); | |||
5165 | if (C->getType() != OpTy) | |||
5166 | C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, | |||
5167 | OpTy, false), | |||
5168 | C, OpTy); | |||
5169 | ||||
5170 | CI->setOperand(1, C); | |||
5171 | } | |||
5172 | } | |||
5173 | ||||
5174 | return FullV; | |||
5175 | } | |||
5176 | ||||
5177 | /// Helper for Rewrite. PHI nodes are special because the use of their operands | |||
5178 | /// effectively happens in their predecessor blocks, so the expression may need | |||
5179 | /// to be expanded in multiple places. | |||
5180 | void LSRInstance::RewriteForPHI( | |||
5181 | PHINode *PN, const LSRUse &LU, const LSRFixup &LF, const Formula &F, | |||
5182 | SCEVExpander &Rewriter, SmallVectorImpl<WeakTrackingVH> &DeadInsts) const { | |||
5183 | DenseMap<BasicBlock *, Value *> Inserted; | |||
5184 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) | |||
5185 | if (PN->getIncomingValue(i) == LF.OperandValToReplace) { | |||
5186 | BasicBlock *BB = PN->getIncomingBlock(i); | |||
5187 | ||||
5188 | // If this is a critical edge, split the edge so that we do not insert | |||
5189 | // the code on all predecessor/successor paths. We do this unless this | |||
5190 | // is the canonical backedge for this loop, which complicates post-inc | |||
5191 | // users. | |||
5192 | if (e != 1 && BB->getTerminator()->getNumSuccessors() > 1 && | |||
5193 | !isa<IndirectBrInst>(BB->getTerminator()) && | |||
5194 | !isa<CatchSwitchInst>(BB->getTerminator())) { | |||
5195 | BasicBlock *Parent = PN->getParent(); | |||
5196 | Loop *PNLoop = LI.getLoopFor(Parent); | |||
5197 | if (!PNLoop || Parent != PNLoop->getHeader()) { | |||
5198 | // Split the critical edge. | |||
5199 | BasicBlock *NewBB = nullptr; | |||
5200 | if (!Parent->isLandingPad()) { | |||
5201 | NewBB = SplitCriticalEdge(BB, Parent, | |||
5202 | CriticalEdgeSplittingOptions(&DT, &LI) | |||
5203 | .setMergeIdenticalEdges() | |||
5204 | .setDontDeleteUselessPHIs()); | |||
5205 | } else { | |||
5206 | SmallVector<BasicBlock*, 2> NewBBs; | |||
5207 | SplitLandingPadPredecessors(Parent, BB, "", "", NewBBs, &DT, &LI); | |||
5208 | NewBB = NewBBs[0]; | |||
5209 | } | |||
5210 | // If NewBB==NULL, then SplitCriticalEdge refused to split because all | |||
5211 | // phi predecessors are identical. The simple thing to do is skip | |||
5212 | // splitting in this case rather than complicate the API. | |||
5213 | if (NewBB) { | |||
5214 | // If PN is outside of the loop and BB is in the loop, we want to | |||
5215 | // move the block to be immediately before the PHI block, not | |||
5216 | // immediately after BB. | |||
5217 | if (L->contains(BB) && !L->contains(PN)) | |||
5218 | NewBB->moveBefore(PN->getParent()); | |||
5219 | ||||
5220 | // Splitting the edge can reduce the number of PHI entries we have. | |||
5221 | e = PN->getNumIncomingValues(); | |||
5222 | BB = NewBB; | |||
5223 | i = PN->getBasicBlockIndex(BB); | |||
5224 | } | |||
5225 | } | |||
5226 | } | |||
5227 | ||||
5228 | std::pair<DenseMap<BasicBlock *, Value *>::iterator, bool> Pair = | |||
5229 | Inserted.insert(std::make_pair(BB, static_cast<Value *>(nullptr))); | |||
5230 | if (!Pair.second) | |||
5231 | PN->setIncomingValue(i, Pair.first->second); | |||
5232 | else { | |||
5233 | Value *FullV = Expand(LU, LF, F, BB->getTerminator()->getIterator(), | |||
5234 | Rewriter, DeadInsts); | |||
5235 | ||||
5236 | // If this is reuse-by-noop-cast, insert the noop cast. | |||
5237 | Type *OpTy = LF.OperandValToReplace->getType(); | |||
| ||||
5238 | if (FullV->getType() != OpTy) | |||
5239 | FullV = | |||
5240 | CastInst::Create(CastInst::getCastOpcode(FullV, false, | |||
5241 | OpTy, false), | |||
5242 | FullV, LF.OperandValToReplace->getType(), | |||
5243 | "tmp", BB->getTerminator()); | |||
5244 | ||||
5245 | PN->setIncomingValue(i, FullV); | |||
5246 | Pair.first->second = FullV; | |||
5247 | } | |||
5248 | } | |||
5249 | } | |||
5250 | ||||
5251 | /// Emit instructions for the leading candidate expression for this LSRUse (this | |||
5252 | /// is called "expanding"), and update the UserInst to reference the newly | |||
5253 | /// expanded value. | |||
5254 | void LSRInstance::Rewrite(const LSRUse &LU, const LSRFixup &LF, | |||
5255 | const Formula &F, SCEVExpander &Rewriter, | |||
5256 | SmallVectorImpl<WeakTrackingVH> &DeadInsts) const { | |||
5257 | // First, find an insertion point that dominates UserInst. For PHI nodes, | |||
5258 | // find the nearest block which dominates all the relevant uses. | |||
5259 | if (PHINode *PN = dyn_cast<PHINode>(LF.UserInst)) { | |||
5260 | RewriteForPHI(PN, LU, LF, F, Rewriter, DeadInsts); | |||
5261 | } else { | |||
5262 | Value *FullV = | |||
5263 | Expand(LU, LF, F, LF.UserInst->getIterator(), Rewriter, DeadInsts); | |||
5264 | ||||
5265 | // If this is reuse-by-noop-cast, insert the noop cast. | |||
5266 | Type *OpTy = LF.OperandValToReplace->getType(); | |||
5267 | if (FullV->getType() != OpTy) { | |||
5268 | Instruction *Cast = | |||
5269 | CastInst::Create(CastInst::getCastOpcode(FullV, false, OpTy, false), | |||
5270 | FullV, OpTy, "tmp", LF.UserInst); | |||
5271 | FullV = Cast; | |||
5272 | } | |||
5273 | ||||
5274 | // Update the user. ICmpZero is handled specially here (for now) because | |||
5275 | // Expand may have updated one of the operands of the icmp already, and | |||
5276 | // its new value may happen to be equal to LF.OperandValToReplace, in | |||
5277 | // which case doing replaceUsesOfWith leads to replacing both operands | |||
5278 | // with the same value. TODO: Reorganize this. | |||
5279 | if (LU.Kind == LSRUse::ICmpZero) | |||
5280 | LF.UserInst->setOperand(0, FullV); | |||
5281 | else | |||
5282 | LF.UserInst->replaceUsesOfWith(LF.OperandValToReplace, FullV); | |||
5283 | } | |||
5284 | ||||
5285 | DeadInsts.emplace_back(LF.OperandValToReplace); | |||
5286 | } | |||
5287 | ||||
5288 | /// Rewrite all the fixup locations with new values, following the chosen | |||
5289 | /// solution. | |||
5290 | void LSRInstance::ImplementSolution( | |||
5291 | const SmallVectorImpl<const Formula *> &Solution) { | |||
5292 | // Keep track of instructions we may have made dead, so that | |||
5293 | // we can remove them after we are done working. | |||
5294 | SmallVector<WeakTrackingVH, 16> DeadInsts; | |||
5295 | ||||
5296 | SCEVExpander Rewriter(SE, L->getHeader()->getModule()->getDataLayout(), | |||
5297 | "lsr"); | |||
5298 | #ifndef NDEBUG | |||
5299 | Rewriter.setDebugType(DEBUG_TYPE"loop-reduce"); | |||
5300 | #endif | |||
5301 | Rewriter.disableCanonicalMode(); | |||
5302 | Rewriter.enableLSRMode(); | |||
5303 | Rewriter.setIVIncInsertPos(L, IVIncInsertPos); | |||
5304 | ||||
5305 | // Mark phi nodes that terminate chains so the expander tries to reuse them. | |||
5306 | for (const IVChain &Chain : IVChainVec) { | |||
| ||||
5307 | if (PHINode *PN = dyn_cast<PHINode>(Chain.tailUserInst())) | |||
5308 | Rewriter.setChainedPhi(PN); | |||
5309 | } | |||
5310 | ||||
5311 | // Expand the new value definitions and update the users. | |||
5312 | for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) | |||
5313 | for (const LSRFixup &Fixup : Uses[LUIdx].Fixups) { | |||
5314 | Rewrite(Uses[LUIdx], Fixup, *Solution[LUIdx], Rewriter, DeadInsts); | |||
5315 | Changed = true; | |||
5316 | } | |||
5317 | ||||
5318 | for (const IVChain &Chain : IVChainVec) { | |||
5319 | GenerateIVChain(Chain, Rewriter, DeadInsts); | |||
5320 | Changed = true; | |||
5321 | } | |||
5322 | // Clean up after ourselves. This must be done before deleting any | |||
5323 | // instructions. | |||
5324 | Rewriter.clear(); | |||
5325 | ||||
5326 | Changed |= DeleteTriviallyDeadInstructions(DeadInsts); | |||
5327 | } | |||
5328 | ||||
5329 | LSRInstance::LSRInstance(Loop *L, IVUsers &IU, ScalarEvolution &SE, | |||
5330 | DominatorTree &DT, LoopInfo &LI, | |||
5331 | const TargetTransformInfo &TTI) | |||
5332 | : IU(IU), SE(SE), DT(DT), LI(LI), TTI(TTI), L(L) { | |||
5333 | // If LoopSimplify form is not available, stay out of trouble. | |||
5334 | if (!L->isLoopSimplifyForm()) | |||
5335 | return; | |||
5336 | ||||
5337 | // If there's no interesting work to be done, bail early. | |||
5338 | if (IU.empty()) return; | |||
5339 | ||||
5340 | // If there's too much analysis to be done, bail early. We won't be able to | |||
5341 | // model the problem anyway. | |||
5342 | unsigned NumUsers = 0; | |||
5343 | for (const IVStrideUse &U : IU) { | |||
5344 | if (++NumUsers > MaxIVUsers) { | |||
5345 | (void)U; | |||
5346 | LLVM_DEBUG(dbgs() << "LSR skipping loop, too many IV Users in " << Udo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "LSR skipping loop, too many IV Users in " << U << "\n"; } } while (false) | |||
5347 | << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "LSR skipping loop, too many IV Users in " << U << "\n"; } } while (false); | |||
5348 | return; | |||
5349 | } | |||
5350 | // Bail out if we have a PHI on an EHPad that gets a value from a | |||
5351 | // CatchSwitchInst. Because the CatchSwitchInst cannot be split, there is | |||
5352 | // no good place to stick any instructions. | |||
5353 | if (auto *PN = dyn_cast<PHINode>(U.getUser())) { | |||
5354 | auto *FirstNonPHI = PN->getParent()->getFirstNonPHI(); | |||
5355 | if (isa<FuncletPadInst>(FirstNonPHI) || | |||
5356 | isa<CatchSwitchInst>(FirstNonPHI)) | |||
5357 | for (BasicBlock *PredBB : PN->blocks()) | |||
5358 | if (isa<CatchSwitchInst>(PredBB->getFirstNonPHI())) | |||
5359 | return; | |||
5360 | } | |||
5361 | } | |||
5362 | ||||
5363 | #ifndef NDEBUG | |||
5364 | // All dominating loops must have preheaders, or SCEVExpander may not be able | |||
5365 | // to materialize an AddRecExpr whose Start is an outer AddRecExpr. | |||
5366 | // | |||
5367 | // IVUsers analysis should only create users that are dominated by simple loop | |||
5368 | // headers. Since this loop should dominate all of its users, its user list | |||
5369 | // should be empty if this loop itself is not within a simple loop nest. | |||
5370 | for (DomTreeNode *Rung = DT.getNode(L->getLoopPreheader()); | |||
5371 | Rung; Rung = Rung->getIDom()) { | |||
5372 | BasicBlock *BB = Rung->getBlock(); | |||
5373 | const Loop *DomLoop = LI.getLoopFor(BB); | |||
5374 | if (DomLoop && DomLoop->getHeader() == BB) { | |||
5375 | assert(DomLoop->getLoopPreheader() && "LSR needs a simplified loop nest")(static_cast <bool> (DomLoop->getLoopPreheader() && "LSR needs a simplified loop nest") ? void (0) : __assert_fail ("DomLoop->getLoopPreheader() && \"LSR needs a simplified loop nest\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 5375, __extension__ __PRETTY_FUNCTION__)); | |||
5376 | } | |||
5377 | } | |||
5378 | #endif // DEBUG | |||
5379 | ||||
5380 | LLVM_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) | |||
5381 | 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) | |||
5382 | dbgs() << ":\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "\nLSR on loop "; L->getHeader ()->printAsOperand(dbgs(), false); dbgs() << ":\n"; } } while (false); | |||
5383 | ||||
5384 | // First, perform some low-level loop optimizations. | |||
5385 | OptimizeShadowIV(); | |||
5386 | OptimizeLoopTermCond(); | |||
5387 | ||||
5388 | // If loop preparation eliminates all interesting IV users, bail. | |||
5389 | if (IU.empty()) return; | |||
5390 | ||||
5391 | // Skip nested loops until we can model them better with formulae. | |||
5392 | if (!L->empty()) { | |||
5393 | LLVM_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); | |||
5394 | return; | |||
5395 | } | |||
5396 | ||||
5397 | // Start collecting data and preparing for the solver. | |||
5398 | CollectChains(); | |||
5399 | CollectInterestingTypesAndFactors(); | |||
5400 | CollectFixupsAndInitialFormulae(); | |||
5401 | CollectLoopInvariantFixupsAndFormulae(); | |||
5402 | ||||
5403 | if (Uses.empty()) | |||
5404 | return; | |||
5405 | ||||
5406 | LLVM_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 ) | |||
5407 | print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("loop-reduce")) { dbgs() << "LSR found " << Uses .size() << " uses:\n"; print_uses(dbgs()); } } while (false ); | |||
5408 | ||||
5409 | // Now use the reuse data to generate a bunch of interesting ways | |||
5410 | // to formulate the values needed for the uses. | |||
5411 | GenerateAllReuseFormulae(); | |||
5412 | ||||
5413 | FilterOutUndesirableDedicatedRegisters(); | |||
5414 | NarrowSearchSpaceUsingHeuristics(); | |||
5415 | ||||
5416 | SmallVector<const Formula *, 8> Solution; | |||
5417 | Solve(Solution); | |||
5418 | ||||
5419 | // Release memory that is no longer needed. | |||
5420 | Factors.clear(); | |||
5421 | Types.clear(); | |||
5422 | RegUses.clear(); | |||
5423 | ||||
5424 | if (Solution.empty()) | |||
5425 | return; | |||
5426 | ||||
5427 | #ifndef NDEBUG | |||
5428 | // Formulae should be legal. | |||
5429 | for (const LSRUse &LU : Uses) { | |||
5430 | for (const Formula &F : LU.Formulae) | |||
5431 | assert(isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy,(static_cast <bool> (isLegalUse(TTI, LU.MinOffset, LU.MaxOffset , LU.Kind, LU.AccessTy, F) && "Illegal formula generated!" ) ? void (0) : __assert_fail ("isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) && \"Illegal formula generated!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 5432, __extension__ __PRETTY_FUNCTION__)) | |||
5432 | F) && "Illegal formula generated!")(static_cast <bool> (isLegalUse(TTI, LU.MinOffset, LU.MaxOffset , LU.Kind, LU.AccessTy, F) && "Illegal formula generated!" ) ? void (0) : __assert_fail ("isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) && \"Illegal formula generated!\"" , "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/Scalar/LoopStrengthReduce.cpp" , 5432, __extension__ __PRETTY_FUNCTION__)); | |||
5433 | }; | |||
5434 | #endif | |||
5435 | ||||
5436 | // Now that we've decided what we want, make it so. | |||
5437 | ImplementSolution(Solution); | |||
5438 | } | |||
5439 | ||||
5440 | #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) | |||
5441 | void LSRInstance::print_factors_and_types(raw_ostream &OS) const { | |||
5442 | if (Factors.empty() && Types.empty()) return; | |||
5443 | ||||
5444 | OS << "LSR has identified the following interesting factors and types: "; | |||
5445 | bool First = true; | |||
5446 | ||||
5447 | for (int64_t Factor : Factors) { | |||
5448 | if (!First) OS << ", "; | |||
5449 | First = false; | |||
5450 | OS << '*' << Factor; | |||
5451 | } | |||
5452 | ||||
5453 | for (Type *Ty : Types) { | |||
5454 | if (!First) OS << ", "; | |||
5455 | First = false; | |||
5456 | OS << '(' << *Ty << ')'; | |||
5457 | } | |||
5458 | OS << '\n'; | |||
5459 | } | |||
5460 | ||||
5461 | void LSRInstance::print_fixups(raw_ostream &OS) const { | |||
5462 | OS << "LSR is examining the following fixup sites:\n"; | |||
5463 | for (const LSRUse &LU : Uses) | |||
5464 | for (const LSRFixup &LF : LU.Fixups) { | |||
5465 | dbgs() << " "; | |||
5466 | LF.print(OS); | |||
5467 | OS << '\n'; | |||
5468 | } | |||
5469 | } | |||
5470 | ||||
5471 | void LSRInstance::print_uses(raw_ostream &OS) const { | |||
5472 | OS << "LSR is examining the following uses:\n"; | |||
5473 | for (const LSRUse &LU : Uses) { | |||
5474 | dbgs() << " "; | |||
5475 | LU.print(OS); | |||
5476 | OS << '\n'; | |||
5477 | for (const Formula &F : LU.Formulae) { | |||
5478 | OS << " "; | |||
5479 | F.print(OS); | |||
5480 | OS << '\n'; | |||
5481 | } | |||
5482 | } | |||
5483 | } | |||
5484 | ||||
5485 | void LSRInstance::print(raw_ostream &OS) const { | |||
5486 | print_factors_and_types(OS); | |||
5487 | print_fixups(OS); | |||
5488 | print_uses(OS); | |||
5489 | } | |||
5490 | ||||
5491 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void LSRInstance::dump() const { | |||
5492 | print(errs()); errs() << '\n'; | |||
5493 | } | |||
5494 | #endif | |||
5495 | ||||
5496 | namespace { | |||
5497 | ||||
5498 | class LoopStrengthReduce : public LoopPass { | |||
5499 | public: | |||
5500 | static char ID; // Pass ID, replacement for typeid | |||
5501 | ||||
5502 | LoopStrengthReduce(); | |||
5503 | ||||
5504 | private: | |||
5505 | bool runOnLoop(Loop *L, LPPassManager &LPM) override; | |||
5506 | void getAnalysisUsage(AnalysisUsage &AU) const override; | |||
5507 | }; | |||
5508 | ||||
5509 | } // end anonymous namespace | |||
5510 | ||||
5511 | LoopStrengthReduce::LoopStrengthReduce() : LoopPass(ID) { | |||
5512 | initializeLoopStrengthReducePass(*PassRegistry::getPassRegistry()); | |||
5513 | } | |||
5514 | ||||
5515 | void LoopStrengthReduce::getAnalysisUsage(AnalysisUsage &AU) const { | |||
5516 | // We split critical edges, so we change the CFG. However, we do update | |||
5517 | // many analyses if they are around. | |||
5518 | AU.addPreservedID(LoopSimplifyID); | |||
5519 | ||||
5520 | AU.addRequired<LoopInfoWrapperPass>(); | |||
5521 | AU.addPreserved<LoopInfoWrapperPass>(); | |||
5522 | AU.addRequiredID(LoopSimplifyID); | |||
5523 | AU.addRequired<DominatorTreeWrapperPass>(); | |||
5524 | AU.addPreserved<DominatorTreeWrapperPass>(); | |||
5525 | AU.addRequired<ScalarEvolutionWrapperPass>(); | |||
5526 | AU.addPreserved<ScalarEvolutionWrapperPass>(); | |||
5527 | // Requiring LoopSimplify a second time here prevents IVUsers from running | |||
5528 | // twice, since LoopSimplify was invalidated by running ScalarEvolution. | |||
5529 | AU.addRequiredID(LoopSimplifyID); | |||
5530 | AU.addRequired<IVUsersWrapperPass>(); | |||
5531 | AU.addPreserved<IVUsersWrapperPass>(); | |||
5532 | AU.addRequired<TargetTransformInfoWrapperPass>(); | |||
5533 | } | |||
5534 | ||||
5535 | static bool ReduceLoopStrength(Loop *L, IVUsers &IU, ScalarEvolution &SE, | |||
5536 | DominatorTree &DT, LoopInfo &LI, | |||
5537 | const TargetTransformInfo &TTI) { | |||
5538 | bool Changed = false; | |||
5539 | ||||
5540 | // Run the main LSR transformation. | |||
5541 | Changed |= LSRInstance(L, IU, SE, DT, LI, TTI).getChanged(); | |||
5542 | ||||
5543 | // Remove any extra phis created by processing inner loops. | |||
5544 | Changed |= DeleteDeadPHIs(L->getHeader()); | |||
5545 | if (EnablePhiElim && L->isLoopSimplifyForm()) { | |||
5546 | SmallVector<WeakTrackingVH, 16> DeadInsts; | |||
5547 | const DataLayout &DL = L->getHeader()->getModule()->getDataLayout(); | |||
5548 | SCEVExpander Rewriter(SE, DL, "lsr"); | |||
5549 | #ifndef NDEBUG | |||
5550 | Rewriter.setDebugType(DEBUG_TYPE"loop-reduce"); | |||
5551 | #endif | |||
5552 | unsigned numFolded = Rewriter.replaceCongruentIVs(L, &DT, DeadInsts, &TTI); | |||
5553 | if (numFolded) { | |||
5554 | Changed = true; | |||
5555 | DeleteTriviallyDeadInstructions(DeadInsts); | |||
5556 | DeleteDeadPHIs(L->getHeader()); | |||
5557 | } | |||
5558 | } | |||
5559 | return Changed; | |||
5560 | } | |||
5561 | ||||
5562 | bool LoopStrengthReduce::runOnLoop(Loop *L, LPPassManager & /*LPM*/) { | |||
5563 | if (skipLoop(L)) | |||
5564 | return false; | |||
5565 | ||||
5566 | auto &IU = getAnalysis<IVUsersWrapperPass>().getIU(); | |||
5567 | auto &SE = getAnalysis<ScalarEvolutionWrapperPass>().getSE(); | |||
5568 | auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree(); | |||
5569 | auto &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo(); | |||
5570 | const auto &TTI = getAnalysis<TargetTransformInfoWrapperPass>().getTTI( | |||
5571 | *L->getHeader()->getParent()); | |||
5572 | return ReduceLoopStrength(L, IU, SE, DT, LI, TTI); | |||
5573 | } | |||
5574 | ||||
5575 | PreservedAnalyses LoopStrengthReducePass::run(Loop &L, LoopAnalysisManager &AM, | |||
5576 | LoopStandardAnalysisResults &AR, | |||
5577 | LPMUpdater &) { | |||
5578 | if (!ReduceLoopStrength(&L, AM.getResult<IVUsersAnalysis>(L, AR), AR.SE, | |||
5579 | AR.DT, AR.LI, AR.TTI)) | |||
5580 | return PreservedAnalyses::all(); | |||
5581 | ||||
5582 | return getLoopPassPreservedAnalyses(); | |||
5583 | } | |||
5584 | ||||
5585 | char LoopStrengthReduce::ID = 0; | |||
5586 | ||||
5587 | INITIALIZE_PASS_BEGIN(LoopStrengthReduce, "loop-reduce",static void *initializeLoopStrengthReducePassOnce(PassRegistry &Registry) { | |||
5588 | "Loop Strength Reduction", false, false)static void *initializeLoopStrengthReducePassOnce(PassRegistry &Registry) { | |||
5589 | INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)initializeTargetTransformInfoWrapperPassPass(Registry); | |||
5590 | INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry); | |||
5591 | INITIALIZE_PASS_DEPENDENCY(ScalarEvolutionWrapperPass)initializeScalarEvolutionWrapperPassPass(Registry); | |||
5592 | INITIALIZE_PASS_DEPENDENCY(IVUsersWrapperPass)initializeIVUsersWrapperPassPass(Registry); | |||
5593 | INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)initializeLoopInfoWrapperPassPass(Registry); | |||
5594 | INITIALIZE_PASS_DEPENDENCY(LoopSimplify)initializeLoopSimplifyPass(Registry); | |||
5595 | 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 llvm::once_flag InitializeLoopStrengthReducePassFlag ; void llvm::initializeLoopStrengthReducePass(PassRegistry & Registry) { llvm::call_once(InitializeLoopStrengthReducePassFlag , initializeLoopStrengthReducePassOnce, std::ref(Registry)); } | |||
5596 | "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 llvm::once_flag InitializeLoopStrengthReducePassFlag ; void llvm::initializeLoopStrengthReducePass(PassRegistry & Registry) { llvm::call_once(InitializeLoopStrengthReducePassFlag , initializeLoopStrengthReducePassOnce, std::ref(Registry)); } | |||
5597 | ||||
5598 | Pass *llvm::createLoopStrengthReducePass() { return new LoopStrengthReduce(); } |