/Users/buildslave/jenkins/sharedspace/clang-stage2-coverage-R@2/llvm/lib/Analysis/MemorySSA.cpp
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1 | | //===- MemorySSA.cpp - Memory SSA Builder ---------------------------------===// |
2 | | // |
3 | | // The LLVM Compiler Infrastructure |
4 | | // |
5 | | // This file is distributed under the University of Illinois Open Source |
6 | | // License. See LICENSE.TXT for details. |
7 | | // |
8 | | //===----------------------------------------------------------------------===// |
9 | | // |
10 | | // This file implements the MemorySSA class. |
11 | | // |
12 | | //===----------------------------------------------------------------------===// |
13 | | |
14 | | #include "llvm/Analysis/MemorySSA.h" |
15 | | #include "llvm/ADT/DenseMap.h" |
16 | | #include "llvm/ADT/DenseMapInfo.h" |
17 | | #include "llvm/ADT/DenseSet.h" |
18 | | #include "llvm/ADT/DepthFirstIterator.h" |
19 | | #include "llvm/ADT/Hashing.h" |
20 | | #include "llvm/ADT/None.h" |
21 | | #include "llvm/ADT/Optional.h" |
22 | | #include "llvm/ADT/STLExtras.h" |
23 | | #include "llvm/ADT/SmallPtrSet.h" |
24 | | #include "llvm/ADT/SmallVector.h" |
25 | | #include "llvm/ADT/iterator.h" |
26 | | #include "llvm/ADT/iterator_range.h" |
27 | | #include "llvm/Analysis/AliasAnalysis.h" |
28 | | #include "llvm/Analysis/IteratedDominanceFrontier.h" |
29 | | #include "llvm/Analysis/MemoryLocation.h" |
30 | | #include "llvm/IR/AssemblyAnnotationWriter.h" |
31 | | #include "llvm/IR/BasicBlock.h" |
32 | | #include "llvm/IR/CallSite.h" |
33 | | #include "llvm/IR/Dominators.h" |
34 | | #include "llvm/IR/Function.h" |
35 | | #include "llvm/IR/Instruction.h" |
36 | | #include "llvm/IR/Instructions.h" |
37 | | #include "llvm/IR/IntrinsicInst.h" |
38 | | #include "llvm/IR/Intrinsics.h" |
39 | | #include "llvm/IR/LLVMContext.h" |
40 | | #include "llvm/IR/PassManager.h" |
41 | | #include "llvm/IR/Use.h" |
42 | | #include "llvm/Pass.h" |
43 | | #include "llvm/Support/AtomicOrdering.h" |
44 | | #include "llvm/Support/Casting.h" |
45 | | #include "llvm/Support/CommandLine.h" |
46 | | #include "llvm/Support/Compiler.h" |
47 | | #include "llvm/Support/Debug.h" |
48 | | #include "llvm/Support/ErrorHandling.h" |
49 | | #include "llvm/Support/FormattedStream.h" |
50 | | #include "llvm/Support/raw_ostream.h" |
51 | | #include <algorithm> |
52 | | #include <cassert> |
53 | | #include <iterator> |
54 | | #include <memory> |
55 | | #include <utility> |
56 | | |
57 | | using namespace llvm; |
58 | | |
59 | | #define DEBUG_TYPE "memoryssa" |
60 | | |
61 | 41.6k | INITIALIZE_PASS_BEGIN41.6k (MemorySSAWrapperPass, "memoryssa", "Memory SSA", false,
|
62 | 41.6k | true) |
63 | 41.6k | INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) |
64 | 41.6k | INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass) |
65 | 41.6k | INITIALIZE_PASS_END(MemorySSAWrapperPass, "memoryssa", "Memory SSA", false, |
66 | | true) |
67 | | |
68 | 7.91k | INITIALIZE_PASS_BEGIN7.91k (MemorySSAPrinterLegacyPass, "print-memoryssa",
|
69 | 7.91k | "Memory SSA Printer", false, false) |
70 | 7.91k | INITIALIZE_PASS_DEPENDENCY(MemorySSAWrapperPass) |
71 | 7.91k | INITIALIZE_PASS_END(MemorySSAPrinterLegacyPass, "print-memoryssa", |
72 | | "Memory SSA Printer", false, false) |
73 | | |
74 | | static cl::opt<unsigned> MaxCheckLimit( |
75 | | "memssa-check-limit", cl::Hidden, cl::init(100), |
76 | | cl::desc("The maximum number of stores/phis MemorySSA" |
77 | | "will consider trying to walk past (default = 100)")); |
78 | | |
79 | | static cl::opt<bool> |
80 | | VerifyMemorySSA("verify-memoryssa", cl::init(false), cl::Hidden, |
81 | | cl::desc("Verify MemorySSA in legacy printer pass.")); |
82 | | |
83 | | namespace llvm { |
84 | | |
85 | | /// \brief An assembly annotator class to print Memory SSA information in |
86 | | /// comments. |
87 | | class MemorySSAAnnotatedWriter : public AssemblyAnnotationWriter { |
88 | | friend class MemorySSA; |
89 | | |
90 | | const MemorySSA *MSSA; |
91 | | |
92 | | public: |
93 | 82 | MemorySSAAnnotatedWriter(const MemorySSA *M) : MSSA(M) {} |
94 | | |
95 | | void emitBasicBlockStartAnnot(const BasicBlock *BB, |
96 | 228 | formatted_raw_ostream &OS) override { |
97 | 228 | if (MemoryAccess *MA = MSSA->getMemoryAccess(BB)) |
98 | 69 | OS << "; " << *MA << "\n"; |
99 | 228 | } |
100 | | |
101 | | void emitInstructionAnnot(const Instruction *I, |
102 | 724 | formatted_raw_ostream &OS) override { |
103 | 724 | if (MemoryAccess *MA = MSSA->getMemoryAccess(I)) |
104 | 370 | OS << "; " << *MA << "\n"; |
105 | 724 | } |
106 | | }; |
107 | | |
108 | | } // end namespace llvm |
109 | | |
110 | | namespace { |
111 | | |
112 | | /// Our current alias analysis API differentiates heavily between calls and |
113 | | /// non-calls, and functions called on one usually assert on the other. |
114 | | /// This class encapsulates the distinction to simplify other code that wants |
115 | | /// "Memory affecting instructions and related data" to use as a key. |
116 | | /// For example, this class is used as a densemap key in the use optimizer. |
117 | | class MemoryLocOrCall { |
118 | | public: |
119 | | bool IsCall = false; |
120 | | |
121 | | MemoryLocOrCall() = default; |
122 | | MemoryLocOrCall(MemoryUseOrDef *MUD) |
123 | 2.23M | : MemoryLocOrCall(MUD->getMemoryInst()) {} |
124 | | MemoryLocOrCall(const MemoryUseOrDef *MUD) |
125 | 1 | : MemoryLocOrCall(MUD->getMemoryInst()) {} |
126 | | |
127 | 2.23M | MemoryLocOrCall(Instruction *Inst) { |
128 | 2.23M | if (ImmutableCallSite(Inst)2.23M ) { |
129 | 59.0k | IsCall = true; |
130 | 59.0k | CS = ImmutableCallSite(Inst); |
131 | 2.23M | } else { |
132 | 2.17M | IsCall = false; |
133 | 2.17M | // There is no such thing as a memorylocation for a fence inst, and it is |
134 | 2.17M | // unique in that regard. |
135 | 2.17M | if (!isa<FenceInst>(Inst)) |
136 | 2.17M | Loc = MemoryLocation::get(Inst); |
137 | 2.17M | } |
138 | 2.23M | } |
139 | | |
140 | 7.83M | explicit MemoryLocOrCall(const MemoryLocation &Loc) : Loc(Loc) {} |
141 | | |
142 | 60.0k | ImmutableCallSite getCS() const { |
143 | 60.0k | assert(IsCall); |
144 | 60.0k | return CS; |
145 | 60.0k | } |
146 | | |
147 | 5.55M | MemoryLocation getLoc() const { |
148 | 5.55M | assert(!IsCall); |
149 | 5.55M | return Loc; |
150 | 5.55M | } |
151 | | |
152 | 30.4M | bool operator==(const MemoryLocOrCall &Other) const { |
153 | 30.4M | if (IsCall != Other.IsCall) |
154 | 98.9k | return false; |
155 | 30.3M | |
156 | 30.3M | if (30.3M IsCall30.3M ) |
157 | 30.9k | return CS.getCalledValue() == Other.CS.getCalledValue(); |
158 | 30.2M | return Loc == Other.Loc; |
159 | 30.2M | } |
160 | | |
161 | | private: |
162 | | union { |
163 | | ImmutableCallSite CS; |
164 | | MemoryLocation Loc; |
165 | | }; |
166 | | }; |
167 | | |
168 | | } // end anonymous namespace |
169 | | |
170 | | namespace llvm { |
171 | | |
172 | | template <> struct DenseMapInfo<MemoryLocOrCall> { |
173 | 4.98M | static inline MemoryLocOrCall getEmptyKey() { |
174 | 4.98M | return MemoryLocOrCall(DenseMapInfo<MemoryLocation>::getEmptyKey()); |
175 | 4.98M | } |
176 | | |
177 | 2.85M | static inline MemoryLocOrCall getTombstoneKey() { |
178 | 2.85M | return MemoryLocOrCall(DenseMapInfo<MemoryLocation>::getTombstoneKey()); |
179 | 2.85M | } |
180 | | |
181 | 2.56M | static unsigned getHashValue(const MemoryLocOrCall &MLOC) { |
182 | 2.56M | if (MLOC.IsCall) |
183 | 60.0k | return hash_combine(MLOC.IsCall, |
184 | 60.0k | DenseMapInfo<const Value *>::getHashValue( |
185 | 60.0k | MLOC.getCS().getCalledValue())); |
186 | 2.50M | return hash_combine( |
187 | 2.50M | MLOC.IsCall, DenseMapInfo<MemoryLocation>::getHashValue(MLOC.getLoc())); |
188 | 2.50M | } |
189 | | |
190 | 30.4M | static bool isEqual(const MemoryLocOrCall &LHS, const MemoryLocOrCall &RHS) { |
191 | 30.4M | return LHS == RHS; |
192 | 30.4M | } |
193 | | }; |
194 | | |
195 | | enum class Reorderability { Always, IfNoAlias, Never }; |
196 | | |
197 | | } // end namespace llvm |
198 | | |
199 | | /// This does one-way checks to see if Use could theoretically be hoisted above |
200 | | /// MayClobber. This will not check the other way around. |
201 | | /// |
202 | | /// This assumes that, for the purposes of MemorySSA, Use comes directly after |
203 | | /// MayClobber, with no potentially clobbering operations in between them. |
204 | | /// (Where potentially clobbering ops are memory barriers, aliased stores, etc.) |
205 | | static Reorderability getLoadReorderability(const LoadInst *Use, |
206 | 2.53k | const LoadInst *MayClobber) { |
207 | 2.53k | bool VolatileUse = Use->isVolatile(); |
208 | 2.53k | bool VolatileClobber = MayClobber->isVolatile(); |
209 | 2.53k | // Volatile operations may never be reordered with other volatile operations. |
210 | 2.53k | if (VolatileUse && 2.53k VolatileClobber0 ) |
211 | 0 | return Reorderability::Never; |
212 | 2.53k | |
213 | 2.53k | // The lang ref allows reordering of volatile and non-volatile operations. |
214 | 2.53k | // Whether an aliasing nonvolatile load and volatile load can be reordered, |
215 | 2.53k | // though, is ambiguous. Because it may not be best to exploit this ambiguity, |
216 | 2.53k | // we only allow volatile/non-volatile reordering if the volatile and |
217 | 2.53k | // non-volatile operations don't alias. |
218 | 2.53k | Reorderability Result = VolatileUse || 2.53k VolatileClobber2.53k |
219 | 2.52k | ? Reorderability::IfNoAlias |
220 | 10 | : Reorderability::Always; |
221 | 2.53k | |
222 | 2.53k | // If a load is seq_cst, it cannot be moved above other loads. If its ordering |
223 | 2.53k | // is weaker, it can be moved above other loads. We just need to be sure that |
224 | 2.53k | // MayClobber isn't an acquire load, because loads can't be moved above |
225 | 2.53k | // acquire loads. |
226 | 2.53k | // |
227 | 2.53k | // Note that this explicitly *does* allow the free reordering of monotonic (or |
228 | 2.53k | // weaker) loads of the same address. |
229 | 2.53k | bool SeqCstUse = Use->getOrdering() == AtomicOrdering::SequentiallyConsistent; |
230 | 2.53k | bool MayClobberIsAcquire = isAtLeastOrStrongerThan(MayClobber->getOrdering(), |
231 | 2.53k | AtomicOrdering::Acquire); |
232 | 2.53k | if (SeqCstUse || 2.53k MayClobberIsAcquire2.53k ) |
233 | 12 | return Reorderability::Never; |
234 | 2.52k | return Result; |
235 | 2.52k | } |
236 | | |
237 | | static bool instructionClobbersQuery(MemoryDef *MD, |
238 | | const MemoryLocation &UseLoc, |
239 | | const Instruction *UseInst, |
240 | 4.41M | AliasAnalysis &AA) { |
241 | 4.41M | Instruction *DefInst = MD->getMemoryInst(); |
242 | 4.41M | assert(DefInst && "Defining instruction not actually an instruction"); |
243 | 4.41M | ImmutableCallSite UseCS(UseInst); |
244 | 4.41M | |
245 | 4.41M | if (const IntrinsicInst *II4.41M = dyn_cast<IntrinsicInst>(DefInst)) { |
246 | 187k | // These intrinsics will show up as affecting memory, but they are just |
247 | 187k | // markers. |
248 | 187k | switch (II->getIntrinsicID()) { |
249 | 94.1k | case Intrinsic::lifetime_start: |
250 | 94.1k | if (UseCS) |
251 | 404 | return false; |
252 | 93.7k | return AA.isMustAlias(MemoryLocation(II->getArgOperand(1)), UseLoc); |
253 | 47.2k | case Intrinsic::lifetime_end: |
254 | 47.2k | case Intrinsic::invariant_start: |
255 | 47.2k | case Intrinsic::invariant_end: |
256 | 47.2k | case Intrinsic::assume: |
257 | 47.2k | return false; |
258 | 46.4k | default: |
259 | 46.4k | break; |
260 | 4.27M | } |
261 | 4.27M | } |
262 | 4.27M | |
263 | 4.27M | if (4.27M UseCS4.27M ) { |
264 | 21.1k | ModRefInfo I = AA.getModRefInfo(DefInst, UseCS); |
265 | 21.1k | return I != MRI_NoModRef; |
266 | 21.1k | } |
267 | 4.25M | |
268 | 4.25M | if (auto *4.25M DefLoad4.25M = dyn_cast<LoadInst>(DefInst)) { |
269 | 2.53k | if (auto *UseLoad2.53k = dyn_cast<LoadInst>(UseInst)) { |
270 | 2.53k | switch (getLoadReorderability(UseLoad, DefLoad)) { |
271 | 0 | case Reorderability::Always: |
272 | 0 | return false; |
273 | 12 | case Reorderability::Never: |
274 | 12 | return true; |
275 | 2.52k | case Reorderability::IfNoAlias: |
276 | 2.52k | return !AA.isNoAlias(UseLoc, MemoryLocation::get(DefLoad)); |
277 | 4.25M | } |
278 | 4.25M | } |
279 | 2.53k | } |
280 | 4.25M | |
281 | 4.25M | return AA.getModRefInfo(DefInst, UseLoc) & MRI_Mod; |
282 | 4.25M | } |
283 | | |
284 | | static bool instructionClobbersQuery(MemoryDef *MD, const MemoryUseOrDef *MU, |
285 | | const MemoryLocOrCall &UseMLOC, |
286 | 1.54M | AliasAnalysis &AA) { |
287 | 1.54M | // FIXME: This is a temporary hack to allow a single instructionClobbersQuery |
288 | 1.54M | // to exist while MemoryLocOrCall is pushed through places. |
289 | 1.54M | if (UseMLOC.IsCall) |
290 | 16.9k | return instructionClobbersQuery(MD, MemoryLocation(), MU->getMemoryInst(), |
291 | 16.9k | AA); |
292 | 1.52M | return instructionClobbersQuery(MD, UseMLOC.getLoc(), MU->getMemoryInst(), |
293 | 1.52M | AA); |
294 | 1.52M | } |
295 | | |
296 | | // Return true when MD may alias MU, return false otherwise. |
297 | | bool MemorySSAUtil::defClobbersUseOrDef(MemoryDef *MD, const MemoryUseOrDef *MU, |
298 | 1 | AliasAnalysis &AA) { |
299 | 1 | return instructionClobbersQuery(MD, MU, MemoryLocOrCall(MU), AA); |
300 | 1 | } |
301 | | |
302 | | namespace { |
303 | | |
304 | | struct UpwardsMemoryQuery { |
305 | | // True if our original query started off as a call |
306 | | bool IsCall = false; |
307 | | // The pointer location we started the query with. This will be empty if |
308 | | // IsCall is true. |
309 | | MemoryLocation StartingLoc; |
310 | | // This is the instruction we were querying about. |
311 | | const Instruction *Inst = nullptr; |
312 | | // The MemoryAccess we actually got called with, used to test local domination |
313 | | const MemoryAccess *OriginalAccess = nullptr; |
314 | | |
315 | 2 | UpwardsMemoryQuery() = default; |
316 | | |
317 | | UpwardsMemoryQuery(const Instruction *Inst, const MemoryAccess *Access) |
318 | 910k | : IsCall(ImmutableCallSite(Inst)), Inst(Inst), OriginalAccess(Access) { |
319 | 910k | if (!IsCall) |
320 | 907k | StartingLoc = MemoryLocation::get(Inst); |
321 | 910k | } |
322 | | }; |
323 | | |
324 | | } // end anonymous namespace |
325 | | |
326 | | static bool lifetimeEndsAt(MemoryDef *MD, const MemoryLocation &Loc, |
327 | 1.52M | AliasAnalysis &AA) { |
328 | 1.52M | Instruction *Inst = MD->getMemoryInst(); |
329 | 1.52M | if (IntrinsicInst *II1.52M = dyn_cast<IntrinsicInst>(Inst)) { |
330 | 82.0k | switch (II->getIntrinsicID()) { |
331 | 10.7k | case Intrinsic::lifetime_end: |
332 | 10.7k | return AA.isMustAlias(MemoryLocation(II->getArgOperand(1)), Loc); |
333 | 71.3k | default: |
334 | 71.3k | return false; |
335 | 1.44M | } |
336 | 1.44M | } |
337 | 1.44M | return false; |
338 | 1.44M | } |
339 | | |
340 | | static bool isUseTriviallyOptimizableToLiveOnEntry(AliasAnalysis &AA, |
341 | 3.16M | const Instruction *I) { |
342 | 3.16M | // If the memory can't be changed, then loads of the memory can't be |
343 | 3.16M | // clobbered. |
344 | 3.16M | // |
345 | 3.16M | // FIXME: We should handle invariant groups, as well. It's a bit harder, |
346 | 3.16M | // because we need to pay close attention to invariant group barriers. |
347 | 3.09M | return isa<LoadInst>(I) && (I->getMetadata(LLVMContext::MD_invariant_load) || |
348 | 3.09M | AA.pointsToConstantMemory(cast<LoadInst>(I)-> |
349 | 3.09M | getPointerOperand())); |
350 | 3.16M | } |
351 | | |
352 | | /// Verifies that `Start` is clobbered by `ClobberAt`, and that nothing |
353 | | /// inbetween `Start` and `ClobberAt` can clobbers `Start`. |
354 | | /// |
355 | | /// This is meant to be as simple and self-contained as possible. Because it |
356 | | /// uses no cache, etc., it can be relatively expensive. |
357 | | /// |
358 | | /// \param Start The MemoryAccess that we want to walk from. |
359 | | /// \param ClobberAt A clobber for Start. |
360 | | /// \param StartLoc The MemoryLocation for Start. |
361 | | /// \param MSSA The MemorySSA isntance that Start and ClobberAt belong to. |
362 | | /// \param Query The UpwardsMemoryQuery we used for our search. |
363 | | /// \param AA The AliasAnalysis we used for our search. |
364 | | static void LLVM_ATTRIBUTE_UNUSED |
365 | | checkClobberSanity(MemoryAccess *Start, MemoryAccess *ClobberAt, |
366 | | const MemoryLocation &StartLoc, const MemorySSA &MSSA, |
367 | 0 | const UpwardsMemoryQuery &Query, AliasAnalysis &AA) { |
368 | 0 | assert(MSSA.dominates(ClobberAt, Start) && "Clobber doesn't dominate start?"); |
369 | 0 |
|
370 | 0 | if (MSSA.isLiveOnEntryDef(Start)) { |
371 | 0 | assert(MSSA.isLiveOnEntryDef(ClobberAt) && |
372 | 0 | "liveOnEntry must clobber itself"); |
373 | 0 | return; |
374 | 0 | } |
375 | 0 |
|
376 | 0 | bool FoundClobber = false; |
377 | 0 | DenseSet<MemoryAccessPair> VisitedPhis; |
378 | 0 | SmallVector<MemoryAccessPair, 8> Worklist; |
379 | 0 | Worklist.emplace_back(Start, StartLoc); |
380 | 0 | // Walk all paths from Start to ClobberAt, while looking for clobbers. If one |
381 | 0 | // is found, complain. |
382 | 0 | while (!Worklist.empty()) { |
383 | 0 | MemoryAccessPair MAP = Worklist.pop_back_val(); |
384 | 0 | // All we care about is that nothing from Start to ClobberAt clobbers Start. |
385 | 0 | // We learn nothing from revisiting nodes. |
386 | 0 | if (!VisitedPhis.insert(MAP).second) |
387 | 0 | continue; |
388 | 0 |
|
389 | 0 | for (MemoryAccess *MA : def_chain(MAP.first)) { |
390 | 0 | if (MA == ClobberAt) { |
391 | 0 | if (auto *MD = dyn_cast<MemoryDef>(MA)) { |
392 | 0 | // instructionClobbersQuery isn't essentially free, so don't use `|=`, |
393 | 0 | // since it won't let us short-circuit. |
394 | 0 | // |
395 | 0 | // Also, note that this can't be hoisted out of the `Worklist` loop, |
396 | 0 | // since MD may only act as a clobber for 1 of N MemoryLocations. |
397 | 0 | FoundClobber = |
398 | 0 | FoundClobber || MSSA.isLiveOnEntryDef(MD) || |
399 | 0 | instructionClobbersQuery(MD, MAP.second, Query.Inst, AA); |
400 | 0 | } |
401 | 0 | break; |
402 | 0 | } |
403 | 0 |
|
404 | 0 | // We should never hit liveOnEntry, unless it's the clobber. |
405 | 0 | assert(!MSSA.isLiveOnEntryDef(MA) && "Hit liveOnEntry before clobber?"); |
406 | 0 |
|
407 | 0 | if (auto *MD = dyn_cast<MemoryDef>(MA)) { |
408 | 0 | (void)MD; |
409 | 0 | assert(!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA) && |
410 | 0 | "Found clobber before reaching ClobberAt!"); |
411 | 0 | continue; |
412 | 0 | } |
413 | 0 |
|
414 | 0 | assert(isa<MemoryPhi>(MA)); |
415 | 0 | Worklist.append(upward_defs_begin({MA, MAP.second}), upward_defs_end()); |
416 | 0 | } |
417 | 0 | } |
418 | 0 |
|
419 | 0 | // If ClobberAt is a MemoryPhi, we can assume something above it acted as a |
420 | 0 | // clobber. Otherwise, `ClobberAt` should've acted as a clobber at some point. |
421 | 0 | assert((isa<MemoryPhi>(ClobberAt) || FoundClobber) && |
422 | 0 | "ClobberAt never acted as a clobber"); |
423 | 0 | } |
424 | | |
425 | | namespace { |
426 | | |
427 | | /// Our algorithm for walking (and trying to optimize) clobbers, all wrapped up |
428 | | /// in one class. |
429 | | class ClobberWalker { |
430 | | /// Save a few bytes by using unsigned instead of size_t. |
431 | | using ListIndex = unsigned; |
432 | | |
433 | | /// Represents a span of contiguous MemoryDefs, potentially ending in a |
434 | | /// MemoryPhi. |
435 | | struct DefPath { |
436 | | MemoryLocation Loc; |
437 | | // Note that, because we always walk in reverse, Last will always dominate |
438 | | // First. Also note that First and Last are inclusive. |
439 | | MemoryAccess *First; |
440 | | MemoryAccess *Last; |
441 | | Optional<ListIndex> Previous; |
442 | | |
443 | | DefPath(const MemoryLocation &Loc, MemoryAccess *First, MemoryAccess *Last, |
444 | | Optional<ListIndex> Previous) |
445 | 6.74M | : Loc(Loc), First(First), Last(Last), Previous(Previous) {} |
446 | | |
447 | | DefPath(const MemoryLocation &Loc, MemoryAccess *Init, |
448 | | Optional<ListIndex> Previous) |
449 | 4.92M | : DefPath(Loc, Init, Init, Previous) {} |
450 | | }; |
451 | | |
452 | | const MemorySSA &MSSA; |
453 | | AliasAnalysis &AA; |
454 | | DominatorTree &DT; |
455 | | UpwardsMemoryQuery *Query; |
456 | | |
457 | | // Phi optimization bookkeeping |
458 | | SmallVector<DefPath, 32> Paths; |
459 | | DenseSet<ConstMemoryAccessPair> VisitedPhis; |
460 | | |
461 | | /// Find the nearest def or phi that `From` can legally be optimized to. |
462 | 1.10M | const MemoryAccess *getWalkTarget(const MemoryPhi *From) const { |
463 | 1.10M | assert(From->getNumOperands() && "Phi with no operands?"); |
464 | 1.10M | |
465 | 1.10M | BasicBlock *BB = From->getBlock(); |
466 | 1.10M | MemoryAccess *Result = MSSA.getLiveOnEntryDef(); |
467 | 1.10M | DomTreeNode *Node = DT.getNode(BB); |
468 | 2.34M | while ((Node = Node->getIDom())2.34M ) { |
469 | 2.17M | auto *Defs = MSSA.getBlockDefs(Node->getBlock()); |
470 | 2.17M | if (Defs) |
471 | 929k | return &*Defs->rbegin(); |
472 | 2.17M | } |
473 | 171k | return Result; |
474 | 1.10M | } |
475 | | |
476 | | /// Result of calling walkToPhiOrClobber. |
477 | | struct UpwardsWalkResult { |
478 | | /// The "Result" of the walk. Either a clobber, the last thing we walked, or |
479 | | /// both. |
480 | | MemoryAccess *Result; |
481 | | bool IsKnownClobber; |
482 | | }; |
483 | | |
484 | | /// Walk to the next Phi or Clobber in the def chain starting at Desc.Last. |
485 | | /// This will update Desc.Last as it walks. It will (optionally) also stop at |
486 | | /// StopAt. |
487 | | /// |
488 | | /// This does not test for whether StopAt is a clobber |
489 | | UpwardsWalkResult |
490 | | walkToPhiOrClobber(DefPath &Desc, |
491 | 3.45M | const MemoryAccess *StopAt = nullptr) const { |
492 | 3.45M | assert(!isa<MemoryUse>(Desc.Last) && "Uses don't exist in my world"); |
493 | 3.45M | |
494 | 5.44M | for (MemoryAccess *Current : def_chain(Desc.Last)) { |
495 | 5.44M | Desc.Last = Current; |
496 | 5.44M | if (Current == StopAt) |
497 | 465k | return {Current, false}; |
498 | 4.98M | |
499 | 4.98M | if (auto *4.98M MD4.98M = dyn_cast<MemoryDef>(Current)) |
500 | 2.97M | if (2.97M MSSA.isLiveOnEntryDef(MD) || |
501 | 2.87M | instructionClobbersQuery(MD, Desc.Loc, Query->Inst, AA)) |
502 | 975k | return {MD, true}; |
503 | 2.00M | } |
504 | 2.00M | |
505 | 3.45M | assert(isa<MemoryPhi>(Desc.Last) && |
506 | 2.00M | "Ended at a non-clobber that's not a phi?"); |
507 | 2.00M | return {Desc.Last, false}; |
508 | 2.00M | } |
509 | | |
510 | | void addSearches(MemoryPhi *Phi, SmallVectorImpl<ListIndex> &PausedSearches, |
511 | 2.00M | ListIndex PriorNode) { |
512 | 2.00M | auto UpwardDefs = make_range(upward_defs_begin({Phi, Paths[PriorNode].Loc}), |
513 | 2.00M | upward_defs_end()); |
514 | 4.92M | for (const MemoryAccessPair &P : UpwardDefs) { |
515 | 4.92M | PausedSearches.push_back(Paths.size()); |
516 | 4.92M | Paths.emplace_back(P.second, P.first, PriorNode); |
517 | 4.92M | } |
518 | 2.00M | } |
519 | | |
520 | | /// Represents a search that terminated after finding a clobber. This clobber |
521 | | /// may or may not be present in the path of defs from LastNode..SearchStart, |
522 | | /// since it may have been retrieved from cache. |
523 | | struct TerminatedPath { |
524 | | MemoryAccess *Clobber; |
525 | | ListIndex LastNode; |
526 | | }; |
527 | | |
528 | | /// Get an access that keeps us from optimizing to the given phi. |
529 | | /// |
530 | | /// PausedSearches is an array of indices into the Paths array. Its incoming |
531 | | /// value is the indices of searches that stopped at the last phi optimization |
532 | | /// target. It's left in an unspecified state. |
533 | | /// |
534 | | /// If this returns None, NewPaused is a vector of searches that terminated |
535 | | /// at StopWhere. Otherwise, NewPaused is left in an unspecified state. |
536 | | Optional<TerminatedPath> |
537 | | getBlockingAccess(const MemoryAccess *StopWhere, |
538 | | SmallVectorImpl<ListIndex> &PausedSearches, |
539 | | SmallVectorImpl<ListIndex> &NewPaused, |
540 | 1.10M | SmallVectorImpl<TerminatedPath> &Terminated) { |
541 | 1.10M | assert(!PausedSearches.empty() && "No searches to continue?"); |
542 | 1.10M | |
543 | 1.10M | // BFS vs DFS really doesn't make a difference here, so just do a DFS with |
544 | 1.10M | // PausedSearches as our stack. |
545 | 3.30M | while (!PausedSearches.empty()3.30M ) { |
546 | 3.00M | ListIndex PathIndex = PausedSearches.pop_back_val(); |
547 | 3.00M | DefPath &Node = Paths[PathIndex]; |
548 | 3.00M | |
549 | 3.00M | // If we've already visited this path with this MemoryLocation, we don't |
550 | 3.00M | // need to do so again. |
551 | 3.00M | // |
552 | 3.00M | // NOTE: That we just drop these paths on the ground makes caching |
553 | 3.00M | // behavior sporadic. e.g. given a diamond: |
554 | 3.00M | // A |
555 | 3.00M | // B C |
556 | 3.00M | // D |
557 | 3.00M | // |
558 | 3.00M | // ...If we walk D, B, A, C, we'll only cache the result of phi |
559 | 3.00M | // optimization for A, B, and D; C will be skipped because it dies here. |
560 | 3.00M | // This arguably isn't the worst thing ever, since: |
561 | 3.00M | // - We generally query things in a top-down order, so if we got below D |
562 | 3.00M | // without needing cache entries for {C, MemLoc}, then chances are |
563 | 3.00M | // that those cache entries would end up ultimately unused. |
564 | 3.00M | // - We still cache things for A, so C only needs to walk up a bit. |
565 | 3.00M | // If this behavior becomes problematic, we can fix without a ton of extra |
566 | 3.00M | // work. |
567 | 3.00M | if (!VisitedPhis.insert({Node.Last, Node.Loc}).second) |
568 | 904k | continue; |
569 | 2.10M | |
570 | 2.10M | UpwardsWalkResult Res = walkToPhiOrClobber(Node, /*StopAt=*/StopWhere); |
571 | 2.10M | if (Res.IsKnownClobber2.10M ) { |
572 | 803k | assert(Res.Result != StopWhere); |
573 | 803k | // If this wasn't a cache hit, we hit a clobber when walking. That's a |
574 | 803k | // failure. |
575 | 803k | TerminatedPath Term{Res.Result, PathIndex}; |
576 | 803k | if (!MSSA.dominates(Res.Result, StopWhere)) |
577 | 803k | return Term; |
578 | 0 |
|
579 | 0 | // Otherwise, it's a valid thing to potentially optimize to. |
580 | 0 | Terminated.push_back(Term); |
581 | 0 | continue; |
582 | 0 | } |
583 | 1.30M | |
584 | 1.30M | if (1.30M Res.Result == StopWhere1.30M ) { |
585 | 465k | // We've hit our target. Save this path off for if we want to continue |
586 | 465k | // walking. |
587 | 465k | NewPaused.push_back(PathIndex); |
588 | 465k | continue; |
589 | 465k | } |
590 | 835k | |
591 | 1.30M | assert(!MSSA.isLiveOnEntryDef(Res.Result) && "liveOnEntry is a clobber"); |
592 | 835k | addSearches(cast<MemoryPhi>(Res.Result), PausedSearches, PathIndex); |
593 | 835k | } |
594 | 1.10M | |
595 | 297k | return None; |
596 | 1.10M | } |
597 | | |
598 | | template <typename T, typename Walker> |
599 | | struct generic_def_path_iterator |
600 | | : public iterator_facade_base<generic_def_path_iterator<T, Walker>, |
601 | | std::forward_iterator_tag, T *> { |
602 | 803k | generic_def_path_iterator() = default; |
603 | 803k | generic_def_path_iterator(Walker *W, ListIndex N) : W(W), N(N) {} |
604 | | |
605 | 2.78M | T &operator*() const { return curNode(); } |
606 | | |
607 | 1.17M | generic_def_path_iterator &operator++() { |
608 | 1.17M | N = curNode().Previous; |
609 | 1.17M | return *this; |
610 | 1.17M | } |
611 | | |
612 | 1.97M | bool operator==(const generic_def_path_iterator &O) const { |
613 | 1.97M | if (N.hasValue() != O.N.hasValue()) |
614 | 1.97M | return false; |
615 | 0 | return !N.hasValue() || 0 *N == *O.N0 ; |
616 | 1.97M | } |
617 | | |
618 | | private: |
619 | 3.95M | T &curNode() const { return W->Paths[*N]; } |
620 | | |
621 | | Walker *W = nullptr; |
622 | | Optional<ListIndex> N = None; |
623 | | }; |
624 | | |
625 | | using def_path_iterator = generic_def_path_iterator<DefPath, ClobberWalker>; |
626 | | using const_def_path_iterator = |
627 | | generic_def_path_iterator<const DefPath, const ClobberWalker>; |
628 | | |
629 | 803k | iterator_range<def_path_iterator> def_path(ListIndex From) { |
630 | 803k | return make_range(def_path_iterator(this, From), def_path_iterator()); |
631 | 803k | } |
632 | | |
633 | 0 | iterator_range<const_def_path_iterator> const_def_path(ListIndex From) const { |
634 | 0 | return make_range(const_def_path_iterator(this, From), |
635 | 0 | const_def_path_iterator()); |
636 | 0 | } |
637 | | |
638 | | struct OptznResult { |
639 | | /// The path that contains our result. |
640 | | TerminatedPath PrimaryClobber; |
641 | | /// The paths that we can legally cache back from, but that aren't |
642 | | /// necessarily the result of the Phi optimization. |
643 | | SmallVector<TerminatedPath, 4> OtherClobbers; |
644 | | }; |
645 | | |
646 | 2.78M | ListIndex defPathIndex(const DefPath &N) const { |
647 | 2.78M | // The assert looks nicer if we don't need to do &N |
648 | 2.78M | const DefPath *NP = &N; |
649 | 2.78M | assert(!Paths.empty() && NP >= &Paths.front() && NP <= &Paths.back() && |
650 | 2.78M | "Out of bounds DefPath!"); |
651 | 2.78M | return NP - &Paths.front(); |
652 | 2.78M | } |
653 | | |
654 | | /// Try to optimize a phi as best as we can. Returns a SmallVector of Paths |
655 | | /// that act as legal clobbers. Note that this won't return *all* clobbers. |
656 | | /// |
657 | | /// Phi optimization algorithm tl;dr: |
658 | | /// - Find the earliest def/phi, A, we can optimize to |
659 | | /// - Find if all paths from the starting memory access ultimately reach A |
660 | | /// - If not, optimization isn't possible. |
661 | | /// - Otherwise, walk from A to another clobber or phi, A'. |
662 | | /// - If A' is a def, we're done. |
663 | | /// - If A' is a phi, try to optimize it. |
664 | | /// |
665 | | /// A path is a series of {MemoryAccess, MemoryLocation} pairs. A path |
666 | | /// terminates when a MemoryAccess that clobbers said MemoryLocation is found. |
667 | | OptznResult tryOptimizePhi(MemoryPhi *Phi, MemoryAccess *Start, |
668 | 906k | const MemoryLocation &Loc) { |
669 | 906k | assert(Paths.empty() && VisitedPhis.empty() && |
670 | 906k | "Reset the optimization state."); |
671 | 906k | |
672 | 906k | Paths.emplace_back(Loc, Start, Phi, None); |
673 | 906k | // Stores how many "valid" optimization nodes we had prior to calling |
674 | 906k | // addSearches/getBlockingAccess. Necessary for caching if we had a blocker. |
675 | 906k | auto PriorPathsSize = Paths.size(); |
676 | 906k | |
677 | 906k | SmallVector<ListIndex, 16> PausedSearches; |
678 | 906k | SmallVector<ListIndex, 8> NewPaused; |
679 | 906k | SmallVector<TerminatedPath, 4> TerminatedPaths; |
680 | 906k | |
681 | 906k | addSearches(Phi, PausedSearches, 0); |
682 | 906k | |
683 | 906k | // Moves the TerminatedPath with the "most dominated" Clobber to the end of |
684 | 906k | // Paths. |
685 | 102k | auto MoveDominatedPathToEnd = [&](SmallVectorImpl<TerminatedPath> &Paths) { |
686 | 102k | assert(!Paths.empty() && "Need a path to move"); |
687 | 102k | auto Dom = Paths.begin(); |
688 | 168k | for (auto I = std::next(Dom), E = Paths.end(); I != E168k ; ++I65.2k ) |
689 | 65.2k | if (65.2k !MSSA.dominates(I->Clobber, Dom->Clobber)65.2k ) |
690 | 0 | Dom = I; |
691 | 102k | auto Last = Paths.end() - 1; |
692 | 102k | if (Last != Dom) |
693 | 61.7k | std::iter_swap(Last, Dom); |
694 | 102k | }; |
695 | 906k | |
696 | 906k | MemoryPhi *Current = Phi; |
697 | 1.10M | while (true1.10M ) { |
698 | 1.10M | assert(!MSSA.isLiveOnEntryDef(Current) && |
699 | 1.10M | "liveOnEntry wasn't treated as a clobber?"); |
700 | 1.10M | |
701 | 1.10M | const auto *Target = getWalkTarget(Current); |
702 | 1.10M | // If a TerminatedPath doesn't dominate Target, then it wasn't a legal |
703 | 1.10M | // optimization for the prior phi. |
704 | 1.10M | assert(all_of(TerminatedPaths, [&](const TerminatedPath &P) { |
705 | 1.10M | return MSSA.dominates(P.Clobber, Target); |
706 | 1.10M | })); |
707 | 1.10M | |
708 | 1.10M | // FIXME: This is broken, because the Blocker may be reported to be |
709 | 1.10M | // liveOnEntry, and we'll happily wait for that to disappear (read: never) |
710 | 1.10M | // For the moment, this is fine, since we do nothing with blocker info. |
711 | 1.10M | if (Optional<TerminatedPath> Blocker = getBlockingAccess( |
712 | 803k | Target, PausedSearches, NewPaused, TerminatedPaths)) { |
713 | 803k | |
714 | 803k | // Find the node we started at. We can't search based on N->Last, since |
715 | 803k | // we may have gone around a loop with a different MemoryLocation. |
716 | 1.97M | auto Iter = find_if(def_path(Blocker->LastNode), [&](const DefPath &N) { |
717 | 1.97M | return defPathIndex(N) < PriorPathsSize; |
718 | 1.97M | }); |
719 | 803k | assert(Iter != def_path_iterator()); |
720 | 803k | |
721 | 803k | DefPath &CurNode = *Iter; |
722 | 803k | assert(CurNode.Last == Current); |
723 | 803k | |
724 | 803k | // Two things: |
725 | 803k | // A. We can't reliably cache all of NewPaused back. Consider a case |
726 | 803k | // where we have two paths in NewPaused; one of which can't optimize |
727 | 803k | // above this phi, whereas the other can. If we cache the second path |
728 | 803k | // back, we'll end up with suboptimal cache entries. We can handle |
729 | 803k | // cases like this a bit better when we either try to find all |
730 | 803k | // clobbers that block phi optimization, or when our cache starts |
731 | 803k | // supporting unfinished searches. |
732 | 803k | // B. We can't reliably cache TerminatedPaths back here without doing |
733 | 803k | // extra checks; consider a case like: |
734 | 803k | // T |
735 | 803k | // / \ |
736 | 803k | // D C |
737 | 803k | // \ / |
738 | 803k | // S |
739 | 803k | // Where T is our target, C is a node with a clobber on it, D is a |
740 | 803k | // diamond (with a clobber *only* on the left or right node, N), and |
741 | 803k | // S is our start. Say we walk to D, through the node opposite N |
742 | 803k | // (read: ignoring the clobber), and see a cache entry in the top |
743 | 803k | // node of D. That cache entry gets put into TerminatedPaths. We then |
744 | 803k | // walk up to C (N is later in our worklist), find the clobber, and |
745 | 803k | // quit. If we append TerminatedPaths to OtherClobbers, we'll cache |
746 | 803k | // the bottom part of D to the cached clobber, ignoring the clobber |
747 | 803k | // in N. Again, this problem goes away if we start tracking all |
748 | 803k | // blockers for a given phi optimization. |
749 | 803k | TerminatedPath Result{CurNode.Last, defPathIndex(CurNode)}; |
750 | 803k | return {Result, {}}; |
751 | 803k | } |
752 | 297k | |
753 | 297k | // If there's nothing left to search, then all paths led to valid clobbers |
754 | 297k | // that we got from our cache; pick the nearest to the start, and allow |
755 | 297k | // the rest to be cached back. |
756 | 297k | if (297k NewPaused.empty()297k ) { |
757 | 0 | MoveDominatedPathToEnd(TerminatedPaths); |
758 | 0 | TerminatedPath Result = TerminatedPaths.pop_back_val(); |
759 | 0 | return {Result, std::move(TerminatedPaths)}; |
760 | 0 | } |
761 | 297k | |
762 | 297k | MemoryAccess *DefChainEnd = nullptr; |
763 | 297k | SmallVector<TerminatedPath, 4> Clobbers; |
764 | 434k | for (ListIndex Paused : NewPaused) { |
765 | 434k | UpwardsWalkResult WR = walkToPhiOrClobber(Paths[Paused]); |
766 | 434k | if (WR.IsKnownClobber) |
767 | 168k | Clobbers.push_back({WR.Result, Paused}); |
768 | 434k | else |
769 | 434k | // Micro-opt: If we hit the end of the chain, save it. |
770 | 266k | DefChainEnd = WR.Result; |
771 | 434k | } |
772 | 297k | |
773 | 297k | if (!TerminatedPaths.empty()297k ) { |
774 | 0 | // If we couldn't find the dominating phi/liveOnEntry in the above loop, |
775 | 0 | // do it now. |
776 | 0 | if (!DefChainEnd) |
777 | 0 | for (auto *MA : def_chain(const_cast<MemoryAccess *>(Target))) |
778 | 0 | DefChainEnd = MA; |
779 | 0 |
|
780 | 0 | // If any of the terminated paths don't dominate the phi we'll try to |
781 | 0 | // optimize, we need to figure out what they are and quit. |
782 | 0 | const BasicBlock *ChainBB = DefChainEnd->getBlock(); |
783 | 0 | for (const TerminatedPath &TP : TerminatedPaths) { |
784 | 0 | // Because we know that DefChainEnd is as "high" as we can go, we |
785 | 0 | // don't need local dominance checks; BB dominance is sufficient. |
786 | 0 | if (DT.dominates(ChainBB, TP.Clobber->getBlock())) |
787 | 0 | Clobbers.push_back(TP); |
788 | 0 | } |
789 | 0 | } |
790 | 297k | |
791 | 297k | // If we have clobbers in the def chain, find the one closest to Current |
792 | 297k | // and quit. |
793 | 297k | if (!Clobbers.empty()297k ) { |
794 | 102k | MoveDominatedPathToEnd(Clobbers); |
795 | 102k | TerminatedPath Result = Clobbers.pop_back_val(); |
796 | 102k | return {Result, std::move(Clobbers)}; |
797 | 102k | } |
798 | 194k | |
799 | 297k | assert(all_of(NewPaused, |
800 | 194k | [&](ListIndex I) { return Paths[I].Last == DefChainEnd; })); |
801 | 194k | |
802 | 194k | // Because liveOnEntry is a clobber, this must be a phi. |
803 | 194k | auto *DefChainPhi = cast<MemoryPhi>(DefChainEnd); |
804 | 194k | |
805 | 194k | PriorPathsSize = Paths.size(); |
806 | 194k | PausedSearches.clear(); |
807 | 194k | for (ListIndex I : NewPaused) |
808 | 266k | addSearches(DefChainPhi, PausedSearches, I); |
809 | 1.10M | NewPaused.clear(); |
810 | 1.10M | |
811 | 1.10M | Current = DefChainPhi; |
812 | 1.10M | } |
813 | 906k | } |
814 | | |
815 | 906k | void verifyOptResult(const OptznResult &R) const { |
816 | 906k | assert(all_of(R.OtherClobbers, [&](const TerminatedPath &P) { |
817 | 906k | return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber); |
818 | 906k | })); |
819 | 906k | } |
820 | | |
821 | 906k | void resetPhiOptznState() { |
822 | 906k | Paths.clear(); |
823 | 906k | VisitedPhis.clear(); |
824 | 906k | } |
825 | | |
826 | | public: |
827 | | ClobberWalker(const MemorySSA &MSSA, AliasAnalysis &AA, DominatorTree &DT) |
828 | 516k | : MSSA(MSSA), AA(AA), DT(DT) {} |
829 | | |
830 | 532k | void reset() {} |
831 | | |
832 | | /// Finds the nearest clobber for the given query, optimizing phis if |
833 | | /// possible. |
834 | 910k | MemoryAccess *findClobber(MemoryAccess *Start, UpwardsMemoryQuery &Q) { |
835 | 910k | Query = &Q; |
836 | 910k | |
837 | 910k | MemoryAccess *Current = Start; |
838 | 910k | // This walker pretends uses don't exist. If we're handed one, silently grab |
839 | 910k | // its def. (This has the nice side-effect of ensuring we never cache uses) |
840 | 910k | if (auto *MU = dyn_cast<MemoryUse>(Start)) |
841 | 0 | Current = MU->getDefiningAccess(); |
842 | 910k | |
843 | 910k | DefPath FirstDesc(Q.StartingLoc, Current, Current, None); |
844 | 910k | // Fast path for the overly-common case (no crazy phi optimization |
845 | 910k | // necessary) |
846 | 910k | UpwardsWalkResult WalkResult = walkToPhiOrClobber(FirstDesc); |
847 | 910k | MemoryAccess *Result; |
848 | 910k | if (WalkResult.IsKnownClobber910k ) { |
849 | 4.17k | Result = WalkResult.Result; |
850 | 910k | } else { |
851 | 906k | OptznResult OptRes = tryOptimizePhi(cast<MemoryPhi>(FirstDesc.Last), |
852 | 906k | Current, Q.StartingLoc); |
853 | 906k | verifyOptResult(OptRes); |
854 | 906k | resetPhiOptznState(); |
855 | 906k | Result = OptRes.PrimaryClobber.Clobber; |
856 | 906k | } |
857 | 910k | |
858 | | #ifdef EXPENSIVE_CHECKS |
859 | | checkClobberSanity(Current, Result, Q.StartingLoc, MSSA, Q, AA); |
860 | | #endif |
861 | | return Result; |
862 | 910k | } |
863 | | |
864 | 93 | void verify(const MemorySSA *MSSA) { assert(MSSA == &this->MSSA); } |
865 | | }; |
866 | | |
867 | | struct RenamePassData { |
868 | | DomTreeNode *DTN; |
869 | | DomTreeNode::const_iterator ChildIt; |
870 | | MemoryAccess *IncomingVal; |
871 | | |
872 | | RenamePassData(DomTreeNode *D, DomTreeNode::const_iterator It, |
873 | | MemoryAccess *M) |
874 | 3.72M | : DTN(D), ChildIt(It), IncomingVal(M) {} |
875 | | |
876 | 0 | void swap(RenamePassData &RHS) { |
877 | 0 | std::swap(DTN, RHS.DTN); |
878 | 0 | std::swap(ChildIt, RHS.ChildIt); |
879 | 0 | std::swap(IncomingVal, RHS.IncomingVal); |
880 | 0 | } |
881 | | }; |
882 | | |
883 | | } // end anonymous namespace |
884 | | |
885 | | namespace llvm { |
886 | | |
887 | | /// \brief A MemorySSAWalker that does AA walks to disambiguate accesses. It no |
888 | | /// longer does caching on its own, |
889 | | /// but the name has been retained for the moment. |
890 | | class MemorySSA::CachingWalker final : public MemorySSAWalker { |
891 | | ClobberWalker Walker; |
892 | | bool AutoResetWalker = true; |
893 | | |
894 | | MemoryAccess *getClobberingMemoryAccess(MemoryAccess *, UpwardsMemoryQuery &); |
895 | | void verifyRemoved(MemoryAccess *); |
896 | | |
897 | | public: |
898 | | CachingWalker(MemorySSA *, AliasAnalysis *, DominatorTree *); |
899 | 516k | ~CachingWalker() override = default; |
900 | | |
901 | | using MemorySSAWalker::getClobberingMemoryAccess; |
902 | | |
903 | | MemoryAccess *getClobberingMemoryAccess(MemoryAccess *) override; |
904 | | MemoryAccess *getClobberingMemoryAccess(MemoryAccess *, |
905 | | const MemoryLocation &) override; |
906 | | void invalidateInfo(MemoryAccess *) override; |
907 | | |
908 | | /// Whether we call resetClobberWalker() after each time we *actually* walk to |
909 | | /// answer a clobber query. |
910 | 1.03M | void setAutoResetWalker(bool AutoReset) { AutoResetWalker = AutoReset; } |
911 | | |
912 | | /// Drop the walker's persistent data structures. |
913 | 532k | void resetClobberWalker() { Walker.reset(); } |
914 | | |
915 | 93 | void verify(const MemorySSA *MSSA) override { |
916 | 93 | MemorySSAWalker::verify(MSSA); |
917 | 93 | Walker.verify(MSSA); |
918 | 93 | } |
919 | | }; |
920 | | |
921 | | } // end namespace llvm |
922 | | |
923 | | void MemorySSA::renameSuccessorPhis(BasicBlock *BB, MemoryAccess *IncomingVal, |
924 | 3.72M | bool RenameAllUses) { |
925 | 3.72M | // Pass through values to our successors |
926 | 5.02M | for (const BasicBlock *S : successors(BB)) { |
927 | 5.02M | auto It = PerBlockAccesses.find(S); |
928 | 5.02M | // Rename the phi nodes in our successor block |
929 | 5.02M | if (It == PerBlockAccesses.end() || 5.02M !isa<MemoryPhi>(It->second->front())4.03M ) |
930 | 2.54M | continue; |
931 | 2.47M | AccessList *Accesses = It->second.get(); |
932 | 2.47M | auto *Phi = cast<MemoryPhi>(&Accesses->front()); |
933 | 2.47M | if (RenameAllUses2.47M ) { |
934 | 2 | int PhiIndex = Phi->getBasicBlockIndex(BB); |
935 | 2 | assert(PhiIndex != -1 && "Incomplete phi during partial rename"); |
936 | 2 | Phi->setIncomingValue(PhiIndex, IncomingVal); |
937 | 2 | } else |
938 | 2.47M | Phi->addIncoming(IncomingVal, BB); |
939 | 5.02M | } |
940 | 3.72M | } |
941 | | |
942 | | /// \brief Rename a single basic block into MemorySSA form. |
943 | | /// Uses the standard SSA renaming algorithm. |
944 | | /// \returns The new incoming value. |
945 | | MemoryAccess *MemorySSA::renameBlock(BasicBlock *BB, MemoryAccess *IncomingVal, |
946 | 3.72M | bool RenameAllUses) { |
947 | 3.72M | auto It = PerBlockAccesses.find(BB); |
948 | 3.72M | // Skip most processing if the list is empty. |
949 | 3.72M | if (It != PerBlockAccesses.end()3.72M ) { |
950 | 2.78M | AccessList *Accesses = It->second.get(); |
951 | 7.33M | for (MemoryAccess &L : *Accesses) { |
952 | 7.33M | if (MemoryUseOrDef *MUD7.33M = dyn_cast<MemoryUseOrDef>(&L)) { |
953 | 6.37M | if (MUD->getDefiningAccess() == nullptr || 6.37M RenameAllUses5 ) |
954 | 6.37M | MUD->setDefiningAccess(IncomingVal); |
955 | 6.37M | if (isa<MemoryDef>(&L)) |
956 | 4.12M | IncomingVal = &L; |
957 | 7.33M | } else { |
958 | 958k | IncomingVal = &L; |
959 | 958k | } |
960 | 7.33M | } |
961 | 2.78M | } |
962 | 3.72M | return IncomingVal; |
963 | 3.72M | } |
964 | | |
965 | | /// \brief This is the standard SSA renaming algorithm. |
966 | | /// |
967 | | /// We walk the dominator tree in preorder, renaming accesses, and then filling |
968 | | /// in phi nodes in our successors. |
969 | | void MemorySSA::renamePass(DomTreeNode *Root, MemoryAccess *IncomingVal, |
970 | | SmallPtrSetImpl<BasicBlock *> &Visited, |
971 | 516k | bool SkipVisited, bool RenameAllUses) { |
972 | 516k | SmallVector<RenamePassData, 32> WorkStack; |
973 | 516k | // Skip everything if we already renamed this block and we are skipping. |
974 | 516k | // Note: You can't sink this into the if, because we need it to occur |
975 | 516k | // regardless of whether we skip blocks or not. |
976 | 516k | bool AlreadyVisited = !Visited.insert(Root->getBlock()).second; |
977 | 516k | if (SkipVisited && 516k AlreadyVisited1 ) |
978 | 0 | return; |
979 | 516k | |
980 | 516k | IncomingVal = renameBlock(Root->getBlock(), IncomingVal, RenameAllUses); |
981 | 516k | renameSuccessorPhis(Root->getBlock(), IncomingVal, RenameAllUses); |
982 | 516k | WorkStack.push_back({Root, Root->begin(), IncomingVal}); |
983 | 516k | |
984 | 7.45M | while (!WorkStack.empty()7.45M ) { |
985 | 6.93M | DomTreeNode *Node = WorkStack.back().DTN; |
986 | 6.93M | DomTreeNode::const_iterator ChildIt = WorkStack.back().ChildIt; |
987 | 6.93M | IncomingVal = WorkStack.back().IncomingVal; |
988 | 6.93M | |
989 | 6.93M | if (ChildIt == Node->end()6.93M ) { |
990 | 3.72M | WorkStack.pop_back(); |
991 | 6.93M | } else { |
992 | 3.21M | DomTreeNode *Child = *ChildIt; |
993 | 3.21M | ++WorkStack.back().ChildIt; |
994 | 3.21M | BasicBlock *BB = Child->getBlock(); |
995 | 3.21M | // Note: You can't sink this into the if, because we need it to occur |
996 | 3.21M | // regardless of whether we skip blocks or not. |
997 | 3.21M | AlreadyVisited = !Visited.insert(BB).second; |
998 | 3.21M | if (SkipVisited && 3.21M AlreadyVisited3 ) { |
999 | 0 | // We already visited this during our renaming, which can happen when |
1000 | 0 | // being asked to rename multiple blocks. Figure out the incoming val, |
1001 | 0 | // which is the last def. |
1002 | 0 | // Incoming value can only change if there is a block def, and in that |
1003 | 0 | // case, it's the last block def in the list. |
1004 | 0 | if (auto *BlockDefs = getWritableBlockDefs(BB)) |
1005 | 0 | IncomingVal = &*BlockDefs->rbegin(); |
1006 | 0 | } else |
1007 | 3.21M | IncomingVal = renameBlock(BB, IncomingVal, RenameAllUses); |
1008 | 3.21M | renameSuccessorPhis(BB, IncomingVal, RenameAllUses); |
1009 | 3.21M | WorkStack.push_back({Child, Child->begin(), IncomingVal}); |
1010 | 3.21M | } |
1011 | 6.93M | } |
1012 | 516k | } |
1013 | | |
1014 | | /// \brief This handles unreachable block accesses by deleting phi nodes in |
1015 | | /// unreachable blocks, and marking all other unreachable MemoryAccess's as |
1016 | | /// being uses of the live on entry definition. |
1017 | 5.11k | void MemorySSA::markUnreachableAsLiveOnEntry(BasicBlock *BB) { |
1018 | 5.11k | assert(!DT->isReachableFromEntry(BB) && |
1019 | 5.11k | "Reachable block found while handling unreachable blocks"); |
1020 | 5.11k | |
1021 | 5.11k | // Make sure phi nodes in our reachable successors end up with a |
1022 | 5.11k | // LiveOnEntryDef for our incoming edge, even though our block is forward |
1023 | 5.11k | // unreachable. We could just disconnect these blocks from the CFG fully, |
1024 | 5.11k | // but we do not right now. |
1025 | 4.38k | for (const BasicBlock *S : successors(BB)) { |
1026 | 4.38k | if (!DT->isReachableFromEntry(S)) |
1027 | 3.25k | continue; |
1028 | 1.12k | auto It = PerBlockAccesses.find(S); |
1029 | 1.12k | // Rename the phi nodes in our successor block |
1030 | 1.12k | if (It == PerBlockAccesses.end() || 1.12k !isa<MemoryPhi>(It->second->front())855 ) |
1031 | 779 | continue; |
1032 | 346 | AccessList *Accesses = It->second.get(); |
1033 | 346 | auto *Phi = cast<MemoryPhi>(&Accesses->front()); |
1034 | 346 | Phi->addIncoming(LiveOnEntryDef.get(), BB); |
1035 | 346 | } |
1036 | 5.11k | |
1037 | 5.11k | auto It = PerBlockAccesses.find(BB); |
1038 | 5.11k | if (It == PerBlockAccesses.end()) |
1039 | 2.34k | return; |
1040 | 2.77k | |
1041 | 2.77k | auto &Accesses = It->second; |
1042 | 5.94k | for (auto AI = Accesses->begin(), AE = Accesses->end(); AI != AE5.94k ;) { |
1043 | 3.17k | auto Next = std::next(AI); |
1044 | 3.17k | // If we have a phi, just remove it. We are going to replace all |
1045 | 3.17k | // users with live on entry. |
1046 | 3.17k | if (auto *UseOrDef = dyn_cast<MemoryUseOrDef>(AI)) |
1047 | 3.17k | UseOrDef->setDefiningAccess(LiveOnEntryDef.get()); |
1048 | 3.17k | else |
1049 | 0 | Accesses->erase(AI); |
1050 | 3.17k | AI = Next; |
1051 | 3.17k | } |
1052 | 5.11k | } |
1053 | | |
1054 | | MemorySSA::MemorySSA(Function &Func, AliasAnalysis *AA, DominatorTree *DT) |
1055 | | : AA(AA), DT(DT), F(Func), LiveOnEntryDef(nullptr), Walker(nullptr), |
1056 | 516k | NextID(INVALID_MEMORYACCESS_ID) { |
1057 | 516k | buildMemorySSA(); |
1058 | 516k | } |
1059 | | |
1060 | 516k | MemorySSA::~MemorySSA() { |
1061 | 516k | // Drop all our references |
1062 | 516k | for (const auto &Pair : PerBlockAccesses) |
1063 | 2.77M | for (MemoryAccess &MA : *Pair.second) |
1064 | 7.24M | MA.dropAllReferences(); |
1065 | 516k | } |
1066 | | |
1067 | 3.39M | MemorySSA::AccessList *MemorySSA::getOrCreateAccessList(const BasicBlock *BB) { |
1068 | 3.39M | auto Res = PerBlockAccesses.insert(std::make_pair(BB, nullptr)); |
1069 | 3.39M | |
1070 | 3.39M | if (Res.second) |
1071 | 2.78M | Res.first->second = llvm::make_unique<AccessList>(); |
1072 | 3.39M | return Res.first->second.get(); |
1073 | 3.39M | } |
1074 | | |
1075 | 2.79M | MemorySSA::DefsList *MemorySSA::getOrCreateDefsList(const BasicBlock *BB) { |
1076 | 2.79M | auto Res = PerBlockDefs.insert(std::make_pair(BB, nullptr)); |
1077 | 2.79M | |
1078 | 2.79M | if (Res.second) |
1079 | 2.32M | Res.first->second = llvm::make_unique<DefsList>(); |
1080 | 2.79M | return Res.first->second.get(); |
1081 | 2.79M | } |
1082 | | |
1083 | | namespace llvm { |
1084 | | |
1085 | | /// This class is a batch walker of all MemoryUse's in the program, and points |
1086 | | /// their defining access at the thing that actually clobbers them. Because it |
1087 | | /// is a batch walker that touches everything, it does not operate like the |
1088 | | /// other walkers. This walker is basically performing a top-down SSA renaming |
1089 | | /// pass, where the version stack is used as the cache. This enables it to be |
1090 | | /// significantly more time and memory efficient than using the regular walker, |
1091 | | /// which is walking bottom-up. |
1092 | | class MemorySSA::OptimizeUses { |
1093 | | public: |
1094 | | OptimizeUses(MemorySSA *MSSA, MemorySSAWalker *Walker, AliasAnalysis *AA, |
1095 | | DominatorTree *DT) |
1096 | 516k | : MSSA(MSSA), Walker(Walker), AA(AA), DT(DT) { |
1097 | 516k | Walker = MSSA->getWalker(); |
1098 | 516k | } |
1099 | | |
1100 | | void optimizeUses(); |
1101 | | |
1102 | | private: |
1103 | | /// This represents where a given memorylocation is in the stack. |
1104 | | struct MemlocStackInfo { |
1105 | | // This essentially is keeping track of versions of the stack. Whenever |
1106 | | // the stack changes due to pushes or pops, these versions increase. |
1107 | | unsigned long StackEpoch; |
1108 | | unsigned long PopEpoch; |
1109 | | // This is the lower bound of places on the stack to check. It is equal to |
1110 | | // the place the last stack walk ended. |
1111 | | // Note: Correctness depends on this being initialized to 0, which densemap |
1112 | | // does |
1113 | | unsigned long LowerBound; |
1114 | | const BasicBlock *LowerBoundBlock; |
1115 | | // This is where the last walk for this memory location ended. |
1116 | | unsigned long LastKill; |
1117 | | bool LastKillValid; |
1118 | | }; |
1119 | | |
1120 | | void optimizeUsesInBlock(const BasicBlock *, unsigned long &, unsigned long &, |
1121 | | SmallVectorImpl<MemoryAccess *> &, |
1122 | | DenseMap<MemoryLocOrCall, MemlocStackInfo> &); |
1123 | | |
1124 | | MemorySSA *MSSA; |
1125 | | MemorySSAWalker *Walker; |
1126 | | AliasAnalysis *AA; |
1127 | | DominatorTree *DT; |
1128 | | }; |
1129 | | |
1130 | | } // end namespace llvm |
1131 | | |
1132 | | /// Optimize the uses in a given block This is basically the SSA renaming |
1133 | | /// algorithm, with one caveat: We are able to use a single stack for all |
1134 | | /// MemoryUses. This is because the set of *possible* reaching MemoryDefs is |
1135 | | /// the same for every MemoryUse. The *actual* clobbering MemoryDef is just |
1136 | | /// going to be some position in that stack of possible ones. |
1137 | | /// |
1138 | | /// We track the stack positions that each MemoryLocation needs |
1139 | | /// to check, and last ended at. This is because we only want to check the |
1140 | | /// things that changed since last time. The same MemoryLocation should |
1141 | | /// get clobbered by the same store (getModRefInfo does not use invariantness or |
1142 | | /// things like this, and if they start, we can modify MemoryLocOrCall to |
1143 | | /// include relevant data) |
1144 | | void MemorySSA::OptimizeUses::optimizeUsesInBlock( |
1145 | | const BasicBlock *BB, unsigned long &StackEpoch, unsigned long &PopEpoch, |
1146 | | SmallVectorImpl<MemoryAccess *> &VersionStack, |
1147 | 3.72M | DenseMap<MemoryLocOrCall, MemlocStackInfo> &LocStackInfo) { |
1148 | 3.72M | |
1149 | 3.72M | /// If no accesses, nothing to do. |
1150 | 3.72M | MemorySSA::AccessList *Accesses = MSSA->getWritableBlockAccesses(BB); |
1151 | 3.72M | if (Accesses == nullptr) |
1152 | 948k | return; |
1153 | 2.78M | |
1154 | 2.78M | // Pop everything that doesn't dominate the current block off the stack, |
1155 | 2.78M | // increment the PopEpoch to account for this. |
1156 | 4.42M | while (2.78M true4.42M ) { |
1157 | 4.42M | assert( |
1158 | 4.42M | !VersionStack.empty() && |
1159 | 4.42M | "Version stack should have liveOnEntry sentinel dominating everything"); |
1160 | 4.42M | BasicBlock *BackBlock = VersionStack.back()->getBlock(); |
1161 | 4.42M | if (DT->dominates(BackBlock, BB)) |
1162 | 2.78M | break; |
1163 | 4.88M | while (1.64M VersionStack.back()->getBlock() == BackBlock4.88M ) |
1164 | 3.23M | VersionStack.pop_back(); |
1165 | 4.42M | ++PopEpoch; |
1166 | 4.42M | } |
1167 | 2.78M | |
1168 | 7.33M | for (MemoryAccess &MA : *Accesses) { |
1169 | 7.33M | auto *MU = dyn_cast<MemoryUse>(&MA); |
1170 | 7.33M | if (!MU7.33M ) { |
1171 | 5.08M | VersionStack.push_back(&MA); |
1172 | 5.08M | ++StackEpoch; |
1173 | 5.08M | continue; |
1174 | 5.08M | } |
1175 | 2.25M | |
1176 | 2.25M | if (2.25M isUseTriviallyOptimizableToLiveOnEntry(*AA, MU->getMemoryInst())2.25M ) { |
1177 | 15.3k | MU->setDefiningAccess(MSSA->getLiveOnEntryDef(), true); |
1178 | 15.3k | continue; |
1179 | 15.3k | } |
1180 | 2.23M | |
1181 | 2.23M | MemoryLocOrCall UseMLOC(MU); |
1182 | 2.23M | auto &LocInfo = LocStackInfo[UseMLOC]; |
1183 | 2.23M | // If the pop epoch changed, it means we've removed stuff from top of |
1184 | 2.23M | // stack due to changing blocks. We may have to reset the lower bound or |
1185 | 2.23M | // last kill info. |
1186 | 2.23M | if (LocInfo.PopEpoch != PopEpoch2.23M ) { |
1187 | 2.09M | LocInfo.PopEpoch = PopEpoch; |
1188 | 2.09M | LocInfo.StackEpoch = StackEpoch; |
1189 | 2.09M | // If the lower bound was in something that no longer dominates us, we |
1190 | 2.09M | // have to reset it. |
1191 | 2.09M | // We can't simply track stack size, because the stack may have had |
1192 | 2.09M | // pushes/pops in the meantime. |
1193 | 2.09M | // XXX: This is non-optimal, but only is slower cases with heavily |
1194 | 2.09M | // branching dominator trees. To get the optimal number of queries would |
1195 | 2.09M | // be to make lowerbound and lastkill a per-loc stack, and pop it until |
1196 | 2.09M | // the top of that stack dominates us. This does not seem worth it ATM. |
1197 | 2.09M | // A much cheaper optimization would be to always explore the deepest |
1198 | 2.09M | // branch of the dominator tree first. This will guarantee this resets on |
1199 | 2.09M | // the smallest set of blocks. |
1200 | 2.09M | if (LocInfo.LowerBoundBlock && 2.09M LocInfo.LowerBoundBlock != BB249k && |
1201 | 2.09M | !DT->dominates(LocInfo.LowerBoundBlock, BB)249k ) { |
1202 | 115k | // Reset the lower bound of things to check. |
1203 | 115k | // TODO: Some day we should be able to reset to last kill, rather than |
1204 | 115k | // 0. |
1205 | 115k | LocInfo.LowerBound = 0; |
1206 | 115k | LocInfo.LowerBoundBlock = VersionStack[0]->getBlock(); |
1207 | 115k | LocInfo.LastKillValid = false; |
1208 | 115k | } |
1209 | 2.23M | } else if (142k LocInfo.StackEpoch != StackEpoch142k ) { |
1210 | 114k | // If all that has changed is the StackEpoch, we only have to check the |
1211 | 114k | // new things on the stack, because we've checked everything before. In |
1212 | 114k | // this case, the lower bound of things to check remains the same. |
1213 | 114k | LocInfo.PopEpoch = PopEpoch; |
1214 | 114k | LocInfo.StackEpoch = StackEpoch; |
1215 | 114k | } |
1216 | 2.23M | if (!LocInfo.LastKillValid2.23M ) { |
1217 | 1.96M | LocInfo.LastKill = VersionStack.size() - 1; |
1218 | 1.96M | LocInfo.LastKillValid = true; |
1219 | 1.96M | } |
1220 | 2.23M | |
1221 | 2.23M | // At this point, we should have corrected last kill and LowerBound to be |
1222 | 2.23M | // in bounds. |
1223 | 2.23M | assert(LocInfo.LowerBound < VersionStack.size() && |
1224 | 2.23M | "Lower bound out of range"); |
1225 | 2.23M | assert(LocInfo.LastKill < VersionStack.size() && |
1226 | 2.23M | "Last kill info out of range"); |
1227 | 2.23M | // In any case, the new upper bound is the top of the stack. |
1228 | 2.23M | unsigned long UpperBound = VersionStack.size() - 1; |
1229 | 2.23M | |
1230 | 2.23M | if (UpperBound - LocInfo.LowerBound > MaxCheckLimit2.23M ) { |
1231 | 12.6k | DEBUG(dbgs() << "MemorySSA skipping optimization of " << *MU << " (" |
1232 | 12.6k | << *(MU->getMemoryInst()) << ")" |
1233 | 12.6k | << " because there are " << UpperBound - LocInfo.LowerBound |
1234 | 12.6k | << " stores to disambiguate\n"); |
1235 | 12.6k | // Because we did not walk, LastKill is no longer valid, as this may |
1236 | 12.6k | // have been a kill. |
1237 | 12.6k | LocInfo.LastKillValid = false; |
1238 | 12.6k | continue; |
1239 | 12.6k | } |
1240 | 2.22M | bool FoundClobberResult = false; |
1241 | 3.07M | while (UpperBound > LocInfo.LowerBound3.07M ) { |
1242 | 2.43M | if (isa<MemoryPhi>(VersionStack[UpperBound])2.43M ) { |
1243 | 894k | // For phis, use the walker, see where we ended up, go there |
1244 | 894k | Instruction *UseInst = MU->getMemoryInst(); |
1245 | 894k | MemoryAccess *Result = Walker->getClobberingMemoryAccess(UseInst); |
1246 | 894k | // We are guaranteed to find it or something is wrong |
1247 | 1.35M | while (VersionStack[UpperBound] != Result1.35M ) { |
1248 | 460k | assert(UpperBound != 0); |
1249 | 460k | --UpperBound; |
1250 | 460k | } |
1251 | 894k | FoundClobberResult = true; |
1252 | 894k | break; |
1253 | 894k | } |
1254 | 1.54M | |
1255 | 1.54M | MemoryDef *MD = cast<MemoryDef>(VersionStack[UpperBound]); |
1256 | 1.54M | // If the lifetime of the pointer ends at this instruction, it's live on |
1257 | 1.54M | // entry. |
1258 | 1.54M | if (!UseMLOC.IsCall && 1.54M lifetimeEndsAt(MD, UseMLOC.getLoc(), *AA)1.52M ) { |
1259 | 3 | // Reset UpperBound to liveOnEntryDef's place in the stack |
1260 | 3 | UpperBound = 0; |
1261 | 3 | FoundClobberResult = true; |
1262 | 3 | break; |
1263 | 3 | } |
1264 | 1.54M | if (1.54M instructionClobbersQuery(MD, MU, UseMLOC, *AA)1.54M ) { |
1265 | 690k | FoundClobberResult = true; |
1266 | 690k | break; |
1267 | 690k | } |
1268 | 852k | --UpperBound; |
1269 | 852k | } |
1270 | 2.22M | // At the end of this loop, UpperBound is either a clobber, or lower bound |
1271 | 2.22M | // PHI walking may cause it to be < LowerBound, and in fact, < LastKill. |
1272 | 2.22M | if (FoundClobberResult || 2.22M UpperBound < LocInfo.LastKill640k ) { |
1273 | 1.61M | MU->setDefiningAccess(VersionStack[UpperBound], true); |
1274 | 1.61M | // We were last killed now by where we got to |
1275 | 1.61M | LocInfo.LastKill = UpperBound; |
1276 | 2.22M | } else { |
1277 | 609k | // Otherwise, we checked all the new ones, and now we know we can get to |
1278 | 609k | // LastKill. |
1279 | 609k | MU->setDefiningAccess(VersionStack[LocInfo.LastKill], true); |
1280 | 609k | } |
1281 | 7.33M | LocInfo.LowerBound = VersionStack.size() - 1; |
1282 | 7.33M | LocInfo.LowerBoundBlock = BB; |
1283 | 7.33M | } |
1284 | 3.72M | } |
1285 | | |
1286 | | /// Optimize uses to point to their actual clobbering definitions. |
1287 | 516k | void MemorySSA::OptimizeUses::optimizeUses() { |
1288 | 516k | SmallVector<MemoryAccess *, 16> VersionStack; |
1289 | 516k | DenseMap<MemoryLocOrCall, MemlocStackInfo> LocStackInfo; |
1290 | 516k | VersionStack.push_back(MSSA->getLiveOnEntryDef()); |
1291 | 516k | |
1292 | 516k | unsigned long StackEpoch = 1; |
1293 | 516k | unsigned long PopEpoch = 1; |
1294 | 516k | // We perform a non-recursive top-down dominator tree walk. |
1295 | 516k | for (const auto *DomNode : depth_first(DT->getRootNode())) |
1296 | 3.72M | optimizeUsesInBlock(DomNode->getBlock(), StackEpoch, PopEpoch, VersionStack, |
1297 | 3.72M | LocStackInfo); |
1298 | 516k | } |
1299 | | |
1300 | | void MemorySSA::placePHINodes( |
1301 | | const SmallPtrSetImpl<BasicBlock *> &DefiningBlocks, |
1302 | 516k | const DenseMap<const BasicBlock *, unsigned int> &BBNumbers) { |
1303 | 516k | // Determine where our MemoryPhi's should go |
1304 | 516k | ForwardIDFCalculator IDFs(*DT); |
1305 | 516k | IDFs.setDefiningBlocks(DefiningBlocks); |
1306 | 516k | SmallVector<BasicBlock *, 32> IDFBlocks; |
1307 | 516k | IDFs.calculate(IDFBlocks); |
1308 | 516k | |
1309 | 516k | std::sort(IDFBlocks.begin(), IDFBlocks.end(), |
1310 | 3.94M | [&BBNumbers](const BasicBlock *A, const BasicBlock *B) { |
1311 | 3.94M | return BBNumbers.lookup(A) < BBNumbers.lookup(B); |
1312 | 3.94M | }); |
1313 | 516k | |
1314 | 516k | // Now place MemoryPhi nodes. |
1315 | 516k | for (auto &BB : IDFBlocks) |
1316 | 958k | createMemoryPhi(BB); |
1317 | 516k | } |
1318 | | |
1319 | 516k | void MemorySSA::buildMemorySSA() { |
1320 | 516k | // We create an access to represent "live on entry", for things like |
1321 | 516k | // arguments or users of globals, where the memory they use is defined before |
1322 | 516k | // the beginning of the function. We do not actually insert it into the IR. |
1323 | 516k | // We do not define a live on exit for the immediate uses, and thus our |
1324 | 516k | // semantics do *not* imply that something with no immediate uses can simply |
1325 | 516k | // be removed. |
1326 | 516k | BasicBlock &StartingPoint = F.getEntryBlock(); |
1327 | 516k | LiveOnEntryDef = |
1328 | 516k | llvm::make_unique<MemoryDef>(F.getContext(), nullptr, nullptr, |
1329 | 516k | &StartingPoint, NextID++); |
1330 | 516k | DenseMap<const BasicBlock *, unsigned int> BBNumbers; |
1331 | 516k | unsigned NextBBNum = 0; |
1332 | 516k | |
1333 | 516k | // We maintain lists of memory accesses per-block, trading memory for time. We |
1334 | 516k | // could just look up the memory access for every possible instruction in the |
1335 | 516k | // stream. |
1336 | 516k | SmallPtrSet<BasicBlock *, 32> DefiningBlocks; |
1337 | 516k | // Go through each block, figure out where defs occur, and chain together all |
1338 | 516k | // the accesses. |
1339 | 3.73M | for (BasicBlock &B : F) { |
1340 | 3.73M | BBNumbers[&B] = NextBBNum++; |
1341 | 3.73M | bool InsertIntoDef = false; |
1342 | 3.73M | AccessList *Accesses = nullptr; |
1343 | 3.73M | DefsList *Defs = nullptr; |
1344 | 19.2M | for (Instruction &I : B) { |
1345 | 19.2M | MemoryUseOrDef *MUD = createNewAccess(&I); |
1346 | 19.2M | if (!MUD) |
1347 | 12.8M | continue; |
1348 | 6.37M | |
1349 | 6.37M | if (6.37M !Accesses6.37M ) |
1350 | 2.43M | Accesses = getOrCreateAccessList(&B); |
1351 | 6.37M | Accesses->push_back(MUD); |
1352 | 6.37M | if (isa<MemoryDef>(MUD)6.37M ) { |
1353 | 4.12M | InsertIntoDef = true; |
1354 | 4.12M | if (!Defs) |
1355 | 1.83M | Defs = getOrCreateDefsList(&B); |
1356 | 4.12M | Defs->push_back(*MUD); |
1357 | 4.12M | } |
1358 | 19.2M | } |
1359 | 3.73M | if (InsertIntoDef) |
1360 | 1.83M | DefiningBlocks.insert(&B); |
1361 | 3.73M | } |
1362 | 516k | placePHINodes(DefiningBlocks, BBNumbers); |
1363 | 516k | |
1364 | 516k | // Now do regular SSA renaming on the MemoryDef/MemoryUse. Visited will get |
1365 | 516k | // filled in with all blocks. |
1366 | 516k | SmallPtrSet<BasicBlock *, 16> Visited; |
1367 | 516k | renamePass(DT->getRootNode(), LiveOnEntryDef.get(), Visited); |
1368 | 516k | |
1369 | 516k | CachingWalker *Walker = getWalkerImpl(); |
1370 | 516k | |
1371 | 516k | // We're doing a batch of updates; don't drop useful caches between them. |
1372 | 516k | Walker->setAutoResetWalker(false); |
1373 | 516k | OptimizeUses(this, Walker, AA, DT).optimizeUses(); |
1374 | 516k | Walker->setAutoResetWalker(true); |
1375 | 516k | Walker->resetClobberWalker(); |
1376 | 516k | |
1377 | 516k | // Mark the uses in unreachable blocks as live on entry, so that they go |
1378 | 516k | // somewhere. |
1379 | 516k | for (auto &BB : F) |
1380 | 3.73M | if (3.73M !Visited.count(&BB)3.73M ) |
1381 | 5.11k | markUnreachableAsLiveOnEntry(&BB); |
1382 | 516k | } |
1383 | | |
1384 | 897k | MemorySSAWalker *MemorySSA::getWalker() { return getWalkerImpl(); } |
1385 | | |
1386 | 1.41M | MemorySSA::CachingWalker *MemorySSA::getWalkerImpl() { |
1387 | 1.41M | if (Walker) |
1388 | 897k | return Walker.get(); |
1389 | 516k | |
1390 | 516k | Walker = llvm::make_unique<CachingWalker>(this, AA, DT); |
1391 | 516k | return Walker.get(); |
1392 | 516k | } |
1393 | | |
1394 | | // This is a helper function used by the creation routines. It places NewAccess |
1395 | | // into the access and defs lists for a given basic block, at the given |
1396 | | // insertion point. |
1397 | | void MemorySSA::insertIntoListsForBlock(MemoryAccess *NewAccess, |
1398 | | const BasicBlock *BB, |
1399 | 958k | InsertionPlace Point) { |
1400 | 958k | auto *Accesses = getOrCreateAccessList(BB); |
1401 | 958k | if (Point == Beginning958k ) { |
1402 | 958k | // If it's a phi node, it goes first, otherwise, it goes after any phi |
1403 | 958k | // nodes. |
1404 | 958k | if (isa<MemoryPhi>(NewAccess)958k ) { |
1405 | 958k | Accesses->push_front(NewAccess); |
1406 | 958k | auto *Defs = getOrCreateDefsList(BB); |
1407 | 958k | Defs->push_front(*NewAccess); |
1408 | 958k | } else { |
1409 | 10 | auto AI = find_if_not( |
1410 | 3 | *Accesses, [](const MemoryAccess &MA) { return isa<MemoryPhi>(MA); }); |
1411 | 10 | Accesses->insert(AI, NewAccess); |
1412 | 10 | if (!isa<MemoryUse>(NewAccess)10 ) { |
1413 | 4 | auto *Defs = getOrCreateDefsList(BB); |
1414 | 4 | auto DI = find_if_not( |
1415 | 0 | *Defs, [](const MemoryAccess &MA) { return isa<MemoryPhi>(MA); }); |
1416 | 4 | Defs->insert(DI, *NewAccess); |
1417 | 4 | } |
1418 | 10 | } |
1419 | 958k | } else { |
1420 | 53 | Accesses->push_back(NewAccess); |
1421 | 53 | if (!isa<MemoryUse>(NewAccess)53 ) { |
1422 | 12 | auto *Defs = getOrCreateDefsList(BB); |
1423 | 12 | Defs->push_back(*NewAccess); |
1424 | 12 | } |
1425 | 53 | } |
1426 | 958k | BlockNumberingValid.erase(BB); |
1427 | 958k | } |
1428 | | |
1429 | | void MemorySSA::insertIntoListsBefore(MemoryAccess *What, const BasicBlock *BB, |
1430 | 6 | AccessList::iterator InsertPt) { |
1431 | 6 | auto *Accesses = getWritableBlockAccesses(BB); |
1432 | 6 | bool WasEnd = InsertPt == Accesses->end(); |
1433 | 6 | Accesses->insert(AccessList::iterator(InsertPt), What); |
1434 | 6 | if (!isa<MemoryUse>(What)6 ) { |
1435 | 6 | auto *Defs = getOrCreateDefsList(BB); |
1436 | 6 | // If we got asked to insert at the end, we have an easy job, just shove it |
1437 | 6 | // at the end. If we got asked to insert before an existing def, we also get |
1438 | 6 | // an terator. If we got asked to insert before a use, we have to hunt for |
1439 | 6 | // the next def. |
1440 | 6 | if (WasEnd6 ) { |
1441 | 3 | Defs->push_back(*What); |
1442 | 6 | } else if (3 isa<MemoryDef>(InsertPt)3 ) { |
1443 | 2 | Defs->insert(InsertPt->getDefsIterator(), *What); |
1444 | 3 | } else { |
1445 | 2 | while (InsertPt != Accesses->end() && 2 !isa<MemoryDef>(InsertPt)1 ) |
1446 | 1 | ++InsertPt; |
1447 | 1 | // Either we found a def, or we are inserting at the end |
1448 | 1 | if (InsertPt == Accesses->end()) |
1449 | 1 | Defs->push_back(*What); |
1450 | 1 | else |
1451 | 0 | Defs->insert(InsertPt->getDefsIterator(), *What); |
1452 | 3 | } |
1453 | 6 | } |
1454 | 6 | BlockNumberingValid.erase(BB); |
1455 | 6 | } |
1456 | | |
1457 | | // Move What before Where in the IR. The end result is taht What will belong to |
1458 | | // the right lists and have the right Block set, but will not otherwise be |
1459 | | // correct. It will not have the right defining access, and if it is a def, |
1460 | | // things below it will not properly be updated. |
1461 | | void MemorySSA::moveTo(MemoryUseOrDef *What, BasicBlock *BB, |
1462 | 4 | AccessList::iterator Where) { |
1463 | 4 | // Keep it in the lookup tables, remove from the lists |
1464 | 4 | removeFromLists(What, false); |
1465 | 4 | What->setBlock(BB); |
1466 | 4 | insertIntoListsBefore(What, BB, Where); |
1467 | 4 | } |
1468 | | |
1469 | | void MemorySSA::moveTo(MemoryUseOrDef *What, BasicBlock *BB, |
1470 | 52 | InsertionPlace Point) { |
1471 | 52 | removeFromLists(What, false); |
1472 | 52 | What->setBlock(BB); |
1473 | 52 | insertIntoListsForBlock(What, BB, Point); |
1474 | 52 | } |
1475 | | |
1476 | 958k | MemoryPhi *MemorySSA::createMemoryPhi(BasicBlock *BB) { |
1477 | 958k | assert(!getMemoryAccess(BB) && "MemoryPhi already exists for this BB"); |
1478 | 958k | MemoryPhi *Phi = new MemoryPhi(BB->getContext(), BB, NextID++); |
1479 | 958k | // Phi's always are placed at the front of the block. |
1480 | 958k | insertIntoListsForBlock(Phi, BB, Beginning); |
1481 | 958k | ValueToMemoryAccess[BB] = Phi; |
1482 | 958k | return Phi; |
1483 | 958k | } |
1484 | | |
1485 | | MemoryUseOrDef *MemorySSA::createDefinedAccess(Instruction *I, |
1486 | 13 | MemoryAccess *Definition) { |
1487 | 13 | assert(!isa<PHINode>(I) && "Cannot create a defined access for a PHI"); |
1488 | 13 | MemoryUseOrDef *NewAccess = createNewAccess(I); |
1489 | 13 | assert( |
1490 | 13 | NewAccess != nullptr && |
1491 | 13 | "Tried to create a memory access for a non-memory touching instruction"); |
1492 | 13 | NewAccess->setDefiningAccess(Definition); |
1493 | 13 | return NewAccess; |
1494 | 13 | } |
1495 | | |
1496 | | // Return true if the instruction has ordering constraints. |
1497 | | // Note specifically that this only considers stores and loads |
1498 | | // because others are still considered ModRef by getModRefInfo. |
1499 | 15.1M | static inline bool isOrdered(const Instruction *I) { |
1500 | 15.1M | if (auto *SI15.1M = dyn_cast<StoreInst>(I)) { |
1501 | 0 | if (!SI->isUnordered()) |
1502 | 0 | return true; |
1503 | 15.1M | } else if (auto *15.1M LI15.1M = dyn_cast<LoadInst>(I)) { |
1504 | 2.20M | if (!LI->isUnordered()) |
1505 | 6.70k | return true; |
1506 | 15.1M | } |
1507 | 15.1M | return false; |
1508 | 15.1M | } |
1509 | | |
1510 | | /// \brief Helper function to create new memory accesses |
1511 | 19.2M | MemoryUseOrDef *MemorySSA::createNewAccess(Instruction *I) { |
1512 | 19.2M | // The assume intrinsic has a control dependency which we model by claiming |
1513 | 19.2M | // that it writes arbitrarily. Ignore that fake memory dependency here. |
1514 | 19.2M | // FIXME: Replace this special casing with a more accurate modelling of |
1515 | 19.2M | // assume's control dependency. |
1516 | 19.2M | if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) |
1517 | 225k | if (225k II->getIntrinsicID() == Intrinsic::assume225k ) |
1518 | 73 | return nullptr; |
1519 | 19.2M | |
1520 | 19.2M | // Find out what affect this instruction has on memory. |
1521 | 19.2M | ModRefInfo ModRef = AA->getModRefInfo(I, None); |
1522 | 19.2M | // The isOrdered check is used to ensure that volatiles end up as defs |
1523 | 19.2M | // (atomics end up as ModRef right now anyway). Until we separate the |
1524 | 19.2M | // ordering chain from the memory chain, this enables people to see at least |
1525 | 19.2M | // some relative ordering to volatiles. Note that getClobberingMemoryAccess |
1526 | 19.2M | // will still give an answer that bypasses other volatile loads. TODO: |
1527 | 19.2M | // Separate memory aliasing and ordering into two different chains so that we |
1528 | 19.2M | // can precisely represent both "what memory will this read/write/is clobbered |
1529 | 19.2M | // by" and "what instructions can I move this past". |
1530 | 15.1M | bool Def = bool(ModRef & MRI_Mod) || isOrdered(I); |
1531 | 19.2M | bool Use = bool(ModRef & MRI_Ref); |
1532 | 19.2M | |
1533 | 19.2M | // It's possible for an instruction to not modify memory at all. During |
1534 | 19.2M | // construction, we ignore them. |
1535 | 19.2M | if (!Def && 19.2M !Use15.1M ) |
1536 | 12.8M | return nullptr; |
1537 | 6.37M | |
1538 | 19.2M | assert((Def || Use) && |
1539 | 6.37M | "Trying to create a memory access with a non-memory instruction"); |
1540 | 6.37M | |
1541 | 6.37M | MemoryUseOrDef *MUD; |
1542 | 6.37M | if (Def) |
1543 | 4.12M | MUD = new MemoryDef(I->getContext(), nullptr, I, I->getParent(), NextID++); |
1544 | 6.37M | else |
1545 | 2.25M | MUD = new MemoryUse(I->getContext(), nullptr, I, I->getParent()); |
1546 | 19.2M | ValueToMemoryAccess[I] = MUD; |
1547 | 19.2M | return MUD; |
1548 | 19.2M | } |
1549 | | |
1550 | | /// \brief Returns true if \p Replacer dominates \p Replacee . |
1551 | | bool MemorySSA::dominatesUse(const MemoryAccess *Replacer, |
1552 | 0 | const MemoryAccess *Replacee) const { |
1553 | 0 | if (isa<MemoryUseOrDef>(Replacee)) |
1554 | 0 | return DT->dominates(Replacer->getBlock(), Replacee->getBlock()); |
1555 | 0 | const auto *MP = cast<MemoryPhi>(Replacee); |
1556 | 0 | // For a phi node, the use occurs in the predecessor block of the phi node. |
1557 | 0 | // Since we may occur multiple times in the phi node, we have to check each |
1558 | 0 | // operand to ensure Replacer dominates each operand where Replacee occurs. |
1559 | 0 | for (const Use &Arg : MP->operands()) { |
1560 | 0 | if (Arg.get() != Replacee && |
1561 | 0 | !DT->dominates(Replacer->getBlock(), MP->getIncomingBlock(Arg))) |
1562 | 0 | return false; |
1563 | 0 | } |
1564 | 0 | return true; |
1565 | 0 | } |
1566 | | |
1567 | | /// \brief Properly remove \p MA from all of MemorySSA's lookup tables. |
1568 | 96.4k | void MemorySSA::removeFromLookups(MemoryAccess *MA) { |
1569 | 96.4k | assert(MA->use_empty() && |
1570 | 96.4k | "Trying to remove memory access that still has uses"); |
1571 | 96.4k | BlockNumbering.erase(MA); |
1572 | 96.4k | if (MemoryUseOrDef *MUD = dyn_cast<MemoryUseOrDef>(MA)) |
1573 | 96.3k | MUD->setDefiningAccess(nullptr); |
1574 | 96.4k | // Invalidate our walker's cache if necessary |
1575 | 96.4k | if (!isa<MemoryUse>(MA)) |
1576 | 12.2k | Walker->invalidateInfo(MA); |
1577 | 96.4k | // The call below to erase will destroy MA, so we can't change the order we |
1578 | 96.4k | // are doing things here |
1579 | 96.4k | Value *MemoryInst; |
1580 | 96.4k | if (MemoryUseOrDef *MUD96.4k = dyn_cast<MemoryUseOrDef>(MA)) { |
1581 | 96.3k | MemoryInst = MUD->getMemoryInst(); |
1582 | 96.4k | } else { |
1583 | 67 | MemoryInst = MA->getBlock(); |
1584 | 67 | } |
1585 | 96.4k | auto VMA = ValueToMemoryAccess.find(MemoryInst); |
1586 | 96.4k | if (VMA->second == MA) |
1587 | 96.4k | ValueToMemoryAccess.erase(VMA); |
1588 | 96.4k | } |
1589 | | |
1590 | | /// \brief Properly remove \p MA from all of MemorySSA's lists. |
1591 | | /// |
1592 | | /// Because of the way the intrusive list and use lists work, it is important to |
1593 | | /// do removal in the right order. |
1594 | | /// ShouldDelete defaults to true, and will cause the memory access to also be |
1595 | | /// deleted, not just removed. |
1596 | 96.4k | void MemorySSA::removeFromLists(MemoryAccess *MA, bool ShouldDelete) { |
1597 | 96.4k | // The access list owns the reference, so we erase it from the non-owning list |
1598 | 96.4k | // first. |
1599 | 96.4k | if (!isa<MemoryUse>(MA)96.4k ) { |
1600 | 12.2k | auto DefsIt = PerBlockDefs.find(MA->getBlock()); |
1601 | 12.2k | std::unique_ptr<DefsList> &Defs = DefsIt->second; |
1602 | 12.2k | Defs->remove(*MA); |
1603 | 12.2k | if (Defs->empty()) |
1604 | 159 | PerBlockDefs.erase(DefsIt); |
1605 | 12.2k | } |
1606 | 96.4k | |
1607 | 96.4k | // The erase call here will delete it. If we don't want it deleted, we call |
1608 | 96.4k | // remove instead. |
1609 | 96.4k | auto AccessIt = PerBlockAccesses.find(MA->getBlock()); |
1610 | 96.4k | std::unique_ptr<AccessList> &Accesses = AccessIt->second; |
1611 | 96.4k | if (ShouldDelete) |
1612 | 96.4k | Accesses->erase(MA); |
1613 | 96.4k | else |
1614 | 56 | Accesses->remove(MA); |
1615 | 96.4k | |
1616 | 96.4k | if (Accesses->empty()) |
1617 | 8.96k | PerBlockAccesses.erase(AccessIt); |
1618 | 96.4k | } |
1619 | | |
1620 | 82 | void MemorySSA::print(raw_ostream &OS) const { |
1621 | 82 | MemorySSAAnnotatedWriter Writer(this); |
1622 | 82 | F.print(OS, &Writer); |
1623 | 82 | } |
1624 | | |
1625 | | #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) |
1626 | | LLVM_DUMP_METHOD void MemorySSA::dump() const { print(dbgs()); } |
1627 | | #endif |
1628 | | |
1629 | 93 | void MemorySSA::verifyMemorySSA() const { |
1630 | 93 | verifyDefUses(F); |
1631 | 93 | verifyDomination(F); |
1632 | 93 | verifyOrdering(F); |
1633 | 93 | Walker->verify(this); |
1634 | 93 | } |
1635 | | |
1636 | | /// \brief Verify that the order and existence of MemoryAccesses matches the |
1637 | | /// order and existence of memory affecting instructions. |
1638 | 93 | void MemorySSA::verifyOrdering(Function &F) const { |
1639 | 93 | // Walk all the blocks, comparing what the lookups think and what the access |
1640 | 93 | // lists think, as well as the order in the blocks vs the order in the access |
1641 | 93 | // lists. |
1642 | 93 | SmallVector<MemoryAccess *, 32> ActualAccesses; |
1643 | 93 | SmallVector<MemoryAccess *, 32> ActualDefs; |
1644 | 284 | for (BasicBlock &B : F) { |
1645 | 284 | const AccessList *AL = getBlockAccesses(&B); |
1646 | 284 | const auto *DL = getBlockDefs(&B); |
1647 | 284 | MemoryAccess *Phi = getMemoryAccess(&B); |
1648 | 284 | if (Phi284 ) { |
1649 | 81 | ActualAccesses.push_back(Phi); |
1650 | 81 | ActualDefs.push_back(Phi); |
1651 | 81 | } |
1652 | 284 | |
1653 | 802 | for (Instruction &I : B) { |
1654 | 802 | MemoryAccess *MA = getMemoryAccess(&I); |
1655 | 802 | assert((!MA || (AL && (isa<MemoryUse>(MA) || DL))) && |
1656 | 802 | "We have memory affecting instructions " |
1657 | 802 | "in this block but they are not in the " |
1658 | 802 | "access list or defs list"); |
1659 | 802 | if (MA802 ) { |
1660 | 402 | ActualAccesses.push_back(MA); |
1661 | 402 | if (isa<MemoryDef>(MA)) |
1662 | 234 | ActualDefs.push_back(MA); |
1663 | 402 | } |
1664 | 802 | } |
1665 | 284 | // Either we hit the assert, really have no accesses, or we have both |
1666 | 284 | // accesses and an access list. |
1667 | 284 | // Same with defs. |
1668 | 284 | if (!AL && 284 !DL72 ) |
1669 | 72 | continue; |
1670 | 284 | assert(AL->size() == ActualAccesses.size() && |
1671 | 212 | "We don't have the same number of accesses in the block as on the " |
1672 | 212 | "access list"); |
1673 | 212 | assert((DL || ActualDefs.size() == 0) && |
1674 | 212 | "Either we should have a defs list, or we should have no defs"); |
1675 | 212 | assert((!DL || DL->size() == ActualDefs.size()) && |
1676 | 212 | "We don't have the same number of defs in the block as on the " |
1677 | 212 | "def list"); |
1678 | 212 | auto ALI = AL->begin(); |
1679 | 212 | auto AAI = ActualAccesses.begin(); |
1680 | 695 | while (ALI != AL->end() && 695 AAI != ActualAccesses.end()483 ) { |
1681 | 483 | assert(&*ALI == *AAI && "Not the same accesses in the same order"); |
1682 | 483 | ++ALI; |
1683 | 483 | ++AAI; |
1684 | 483 | } |
1685 | 212 | ActualAccesses.clear(); |
1686 | 212 | if (DL212 ) { |
1687 | 205 | auto DLI = DL->begin(); |
1688 | 205 | auto ADI = ActualDefs.begin(); |
1689 | 520 | while (DLI != DL->end() && 520 ADI != ActualDefs.end()315 ) { |
1690 | 315 | assert(&*DLI == *ADI && "Not the same defs in the same order"); |
1691 | 315 | ++DLI; |
1692 | 315 | ++ADI; |
1693 | 315 | } |
1694 | 205 | } |
1695 | 284 | ActualDefs.clear(); |
1696 | 284 | } |
1697 | 93 | } |
1698 | | |
1699 | | /// \brief Verify the domination properties of MemorySSA by checking that each |
1700 | | /// definition dominates all of its uses. |
1701 | 93 | void MemorySSA::verifyDomination(Function &F) const { |
1702 | | #ifndef NDEBUG |
1703 | | for (BasicBlock &B : F) { |
1704 | | // Phi nodes are attached to basic blocks |
1705 | | if (MemoryPhi *MP = getMemoryAccess(&B)) |
1706 | | for (const Use &U : MP->uses()) |
1707 | | assert(dominates(MP, U) && "Memory PHI does not dominate it's uses"); |
1708 | | |
1709 | | for (Instruction &I : B) { |
1710 | | MemoryAccess *MD = dyn_cast_or_null<MemoryDef>(getMemoryAccess(&I)); |
1711 | | if (!MD) |
1712 | | continue; |
1713 | | |
1714 | | for (const Use &U : MD->uses()) |
1715 | | assert(dominates(MD, U) && "Memory Def does not dominate it's uses"); |
1716 | | } |
1717 | | } |
1718 | | #endif |
1719 | | } |
1720 | | |
1721 | | /// \brief Verify the def-use lists in MemorySSA, by verifying that \p Use |
1722 | | /// appears in the use list of \p Def. |
1723 | 585 | void MemorySSA::verifyUseInDefs(MemoryAccess *Def, MemoryAccess *Use) const { |
1724 | | #ifndef NDEBUG |
1725 | | // The live on entry use may cause us to get a NULL def here |
1726 | | if (!Def) |
1727 | | assert(isLiveOnEntryDef(Use) && |
1728 | | "Null def but use not point to live on entry def"); |
1729 | | else |
1730 | | assert(is_contained(Def->users(), Use) && |
1731 | | "Did not find use in def's use list"); |
1732 | | #endif |
1733 | | } |
1734 | | |
1735 | | /// \brief Verify the immediate use information, by walking all the memory |
1736 | | /// accesses and verifying that, for each use, it appears in the |
1737 | | /// appropriate def's use list |
1738 | 93 | void MemorySSA::verifyDefUses(Function &F) const { |
1739 | 284 | for (BasicBlock &B : F) { |
1740 | 284 | // Phi nodes are attached to basic blocks |
1741 | 284 | if (MemoryPhi *Phi284 = getMemoryAccess(&B)) { |
1742 | 81 | assert(Phi->getNumOperands() == static_cast<unsigned>(std::distance( |
1743 | 81 | pred_begin(&B), pred_end(&B))) && |
1744 | 81 | "Incomplete MemoryPhi Node"); |
1745 | 264 | for (unsigned I = 0, E = Phi->getNumIncomingValues(); I != E264 ; ++I183 ) |
1746 | 183 | verifyUseInDefs(Phi->getIncomingValue(I), Phi); |
1747 | 81 | } |
1748 | 284 | |
1749 | 802 | for (Instruction &I : B) { |
1750 | 802 | if (MemoryUseOrDef *MA802 = getMemoryAccess(&I)) { |
1751 | 402 | verifyUseInDefs(MA->getDefiningAccess(), MA); |
1752 | 402 | } |
1753 | 802 | } |
1754 | 284 | } |
1755 | 93 | } |
1756 | | |
1757 | 2.30M | MemoryUseOrDef *MemorySSA::getMemoryAccess(const Instruction *I) const { |
1758 | 2.30M | return cast_or_null<MemoryUseOrDef>(ValueToMemoryAccess.lookup(I)); |
1759 | 2.30M | } |
1760 | | |
1761 | 2.32k | MemoryPhi *MemorySSA::getMemoryAccess(const BasicBlock *BB) const { |
1762 | 2.32k | return cast_or_null<MemoryPhi>(ValueToMemoryAccess.lookup(cast<Value>(BB))); |
1763 | 2.32k | } |
1764 | | |
1765 | | /// Perform a local numbering on blocks so that instruction ordering can be |
1766 | | /// determined in constant time. |
1767 | | /// TODO: We currently just number in order. If we numbered by N, we could |
1768 | | /// allow at least N-1 sequences of insertBefore or insertAfter (and at least |
1769 | | /// log2(N) sequences of mixed before and after) without needing to invalidate |
1770 | | /// the numbering. |
1771 | 62.3k | void MemorySSA::renumberBlock(const BasicBlock *B) const { |
1772 | 62.3k | // The pre-increment ensures the numbers really start at 1. |
1773 | 62.3k | unsigned long CurrentNumber = 0; |
1774 | 62.3k | const AccessList *AL = getBlockAccesses(B); |
1775 | 62.3k | assert(AL != nullptr && "Asking to renumber an empty block"); |
1776 | 62.3k | for (const auto &I : *AL) |
1777 | 538k | BlockNumbering[&I] = ++CurrentNumber; |
1778 | 62.3k | BlockNumberingValid.insert(B); |
1779 | 62.3k | } |
1780 | | |
1781 | | /// \brief Determine, for two memory accesses in the same block, |
1782 | | /// whether \p Dominator dominates \p Dominatee. |
1783 | | /// \returns True if \p Dominator dominates \p Dominatee. |
1784 | | bool MemorySSA::locallyDominates(const MemoryAccess *Dominator, |
1785 | 96.9k | const MemoryAccess *Dominatee) const { |
1786 | 96.9k | const BasicBlock *DominatorBlock = Dominator->getBlock(); |
1787 | 96.9k | |
1788 | 96.9k | assert((DominatorBlock == Dominatee->getBlock()) && |
1789 | 96.9k | "Asking for local domination when accesses are in different blocks!"); |
1790 | 96.9k | // A node dominates itself. |
1791 | 96.9k | if (Dominatee == Dominator) |
1792 | 0 | return true; |
1793 | 96.9k | |
1794 | 96.9k | // When Dominatee is defined on function entry, it is not dominated by another |
1795 | 96.9k | // memory access. |
1796 | 96.9k | if (96.9k isLiveOnEntryDef(Dominatee)96.9k ) |
1797 | 0 | return false; |
1798 | 96.9k | |
1799 | 96.9k | // When Dominator is defined on function entry, it dominates the other memory |
1800 | 96.9k | // access. |
1801 | 96.9k | if (96.9k isLiveOnEntryDef(Dominator)96.9k ) |
1802 | 6.75k | return true; |
1803 | 90.2k | |
1804 | 90.2k | if (90.2k !BlockNumberingValid.count(DominatorBlock)90.2k ) |
1805 | 62.3k | renumberBlock(DominatorBlock); |
1806 | 96.9k | |
1807 | 96.9k | unsigned long DominatorNum = BlockNumbering.lookup(Dominator); |
1808 | 96.9k | // All numbers start with 1 |
1809 | 96.9k | assert(DominatorNum != 0 && "Block was not numbered properly"); |
1810 | 96.9k | unsigned long DominateeNum = BlockNumbering.lookup(Dominatee); |
1811 | 96.9k | assert(DominateeNum != 0 && "Block was not numbered properly"); |
1812 | 96.9k | return DominatorNum < DominateeNum; |
1813 | 96.9k | } |
1814 | | |
1815 | | bool MemorySSA::dominates(const MemoryAccess *Dominator, |
1816 | 1.24M | const MemoryAccess *Dominatee) const { |
1817 | 1.24M | if (Dominator == Dominatee) |
1818 | 80.9k | return true; |
1819 | 1.16M | |
1820 | 1.16M | if (1.16M isLiveOnEntryDef(Dominatee)1.16M ) |
1821 | 125k | return false; |
1822 | 1.04M | |
1823 | 1.04M | if (1.04M Dominator->getBlock() != Dominatee->getBlock()1.04M ) |
1824 | 945k | return DT->dominates(Dominator->getBlock(), Dominatee->getBlock()); |
1825 | 96.9k | return locallyDominates(Dominator, Dominatee); |
1826 | 96.9k | } |
1827 | | |
1828 | | bool MemorySSA::dominates(const MemoryAccess *Dominator, |
1829 | 0 | const Use &Dominatee) const { |
1830 | 0 | if (MemoryPhi *MP0 = dyn_cast<MemoryPhi>(Dominatee.getUser())) { |
1831 | 0 | BasicBlock *UseBB = MP->getIncomingBlock(Dominatee); |
1832 | 0 | // The def must dominate the incoming block of the phi. |
1833 | 0 | if (UseBB != Dominator->getBlock()) |
1834 | 0 | return DT->dominates(Dominator->getBlock(), UseBB); |
1835 | 0 | // If the UseBB and the DefBB are the same, compare locally. |
1836 | 0 | return locallyDominates(Dominator, cast<MemoryAccess>(Dominatee)); |
1837 | 0 | } |
1838 | 0 | // If it's not a PHI node use, the normal dominates can already handle it. |
1839 | 0 | return dominates(Dominator, cast<MemoryAccess>(Dominatee.getUser())); |
1840 | 0 | } |
1841 | | |
1842 | | const static char LiveOnEntryStr[] = "liveOnEntry"; |
1843 | | |
1844 | 439 | void MemoryAccess::print(raw_ostream &OS) const { |
1845 | 439 | switch (getValueID()) { |
1846 | 69 | case MemoryPhiVal: return static_cast<const MemoryPhi *>(this)->print(OS); |
1847 | 216 | case MemoryDefVal: return static_cast<const MemoryDef *>(this)->print(OS); |
1848 | 154 | case MemoryUseVal: return static_cast<const MemoryUse *>(this)->print(OS); |
1849 | 0 | } |
1850 | 0 | llvm_unreachable0 ("invalid value id"); |
1851 | 0 | } |
1852 | | |
1853 | 216 | void MemoryDef::print(raw_ostream &OS) const { |
1854 | 216 | MemoryAccess *UO = getDefiningAccess(); |
1855 | 216 | |
1856 | 216 | OS << getID() << " = MemoryDef("; |
1857 | 216 | if (UO && 216 UO->getID()216 ) |
1858 | 144 | OS << UO->getID(); |
1859 | 216 | else |
1860 | 72 | OS << LiveOnEntryStr; |
1861 | 216 | OS << ')'; |
1862 | 216 | } |
1863 | | |
1864 | 69 | void MemoryPhi::print(raw_ostream &OS) const { |
1865 | 69 | bool First = true; |
1866 | 69 | OS << getID() << " = MemoryPhi("; |
1867 | 159 | for (const auto &Op : operands()) { |
1868 | 159 | BasicBlock *BB = getIncomingBlock(Op); |
1869 | 159 | MemoryAccess *MA = cast<MemoryAccess>(Op); |
1870 | 159 | if (!First) |
1871 | 90 | OS << ','; |
1872 | 159 | else |
1873 | 69 | First = false; |
1874 | 159 | |
1875 | 159 | OS << '{'; |
1876 | 159 | if (BB->hasName()) |
1877 | 145 | OS << BB->getName(); |
1878 | 159 | else |
1879 | 14 | BB->printAsOperand(OS, false); |
1880 | 159 | OS << ','; |
1881 | 159 | if (unsigned ID = MA->getID()) |
1882 | 143 | OS << ID; |
1883 | 159 | else |
1884 | 16 | OS << LiveOnEntryStr; |
1885 | 159 | OS << '}'; |
1886 | 159 | } |
1887 | 69 | OS << ')'; |
1888 | 69 | } |
1889 | | |
1890 | 154 | void MemoryUse::print(raw_ostream &OS) const { |
1891 | 154 | MemoryAccess *UO = getDefiningAccess(); |
1892 | 154 | OS << "MemoryUse("; |
1893 | 154 | if (UO && 154 UO->getID()154 ) |
1894 | 128 | OS << UO->getID(); |
1895 | 154 | else |
1896 | 26 | OS << LiveOnEntryStr; |
1897 | 154 | OS << ')'; |
1898 | 154 | } |
1899 | | |
1900 | 0 | void MemoryAccess::dump() const { |
1901 | 0 | // Cannot completely remove virtual function even in release mode. |
1902 | | #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) |
1903 | | print(dbgs()); |
1904 | | dbgs() << "\n"; |
1905 | | #endif |
1906 | | } |
1907 | | |
1908 | | char MemorySSAPrinterLegacyPass::ID = 0; |
1909 | | |
1910 | 20 | MemorySSAPrinterLegacyPass::MemorySSAPrinterLegacyPass() : FunctionPass(ID) { |
1911 | 20 | initializeMemorySSAPrinterLegacyPassPass(*PassRegistry::getPassRegistry()); |
1912 | 20 | } |
1913 | | |
1914 | 20 | void MemorySSAPrinterLegacyPass::getAnalysisUsage(AnalysisUsage &AU) const { |
1915 | 20 | AU.setPreservesAll(); |
1916 | 20 | AU.addRequired<MemorySSAWrapperPass>(); |
1917 | 20 | } |
1918 | | |
1919 | 45 | bool MemorySSAPrinterLegacyPass::runOnFunction(Function &F) { |
1920 | 45 | auto &MSSA = getAnalysis<MemorySSAWrapperPass>().getMSSA(); |
1921 | 45 | MSSA.print(dbgs()); |
1922 | 45 | if (VerifyMemorySSA) |
1923 | 44 | MSSA.verifyMemorySSA(); |
1924 | 45 | return false; |
1925 | 45 | } |
1926 | | |
1927 | | AnalysisKey MemorySSAAnalysis::Key; |
1928 | | |
1929 | | MemorySSAAnalysis::Result MemorySSAAnalysis::run(Function &F, |
1930 | 158 | FunctionAnalysisManager &AM) { |
1931 | 158 | auto &DT = AM.getResult<DominatorTreeAnalysis>(F); |
1932 | 158 | auto &AA = AM.getResult<AAManager>(F); |
1933 | 158 | return MemorySSAAnalysis::Result(llvm::make_unique<MemorySSA>(F, &AA, &DT)); |
1934 | 158 | } |
1935 | | |
1936 | | PreservedAnalyses MemorySSAPrinterPass::run(Function &F, |
1937 | 36 | FunctionAnalysisManager &AM) { |
1938 | 36 | OS << "MemorySSA for function: " << F.getName() << "\n"; |
1939 | 36 | AM.getResult<MemorySSAAnalysis>(F).getMSSA().print(OS); |
1940 | 36 | |
1941 | 36 | return PreservedAnalyses::all(); |
1942 | 36 | } |
1943 | | |
1944 | | PreservedAnalyses MemorySSAVerifierPass::run(Function &F, |
1945 | 33 | FunctionAnalysisManager &AM) { |
1946 | 33 | AM.getResult<MemorySSAAnalysis>(F).getMSSA().verifyMemorySSA(); |
1947 | 33 | |
1948 | 33 | return PreservedAnalyses::all(); |
1949 | 33 | } |
1950 | | |
1951 | | char MemorySSAWrapperPass::ID = 0; |
1952 | | |
1953 | 17.4k | MemorySSAWrapperPass::MemorySSAWrapperPass() : FunctionPass(ID) { |
1954 | 17.4k | initializeMemorySSAWrapperPassPass(*PassRegistry::getPassRegistry()); |
1955 | 17.4k | } |
1956 | | |
1957 | 516k | void MemorySSAWrapperPass::releaseMemory() { MSSA.reset(); } |
1958 | | |
1959 | 17.4k | void MemorySSAWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const { |
1960 | 17.4k | AU.setPreservesAll(); |
1961 | 17.4k | AU.addRequiredTransitive<DominatorTreeWrapperPass>(); |
1962 | 17.4k | AU.addRequiredTransitive<AAResultsWrapperPass>(); |
1963 | 17.4k | } |
1964 | | |
1965 | 516k | bool MemorySSAWrapperPass::runOnFunction(Function &F) { |
1966 | 516k | auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree(); |
1967 | 516k | auto &AA = getAnalysis<AAResultsWrapperPass>().getAAResults(); |
1968 | 516k | MSSA.reset(new MemorySSA(F, &AA, &DT)); |
1969 | 516k | return false; |
1970 | 516k | } |
1971 | | |
1972 | 0 | void MemorySSAWrapperPass::verifyAnalysis() const { MSSA->verifyMemorySSA(); } |
1973 | | |
1974 | 1 | void MemorySSAWrapperPass::print(raw_ostream &OS, const Module *M) const { |
1975 | 1 | MSSA->print(OS); |
1976 | 1 | } |
1977 | | |
1978 | 516k | MemorySSAWalker::MemorySSAWalker(MemorySSA *M) : MSSA(M) {} |
1979 | | |
1980 | | MemorySSA::CachingWalker::CachingWalker(MemorySSA *M, AliasAnalysis *A, |
1981 | | DominatorTree *D) |
1982 | 516k | : MemorySSAWalker(M), Walker(*M, *A, *D) {} |
1983 | | |
1984 | 12.2k | void MemorySSA::CachingWalker::invalidateInfo(MemoryAccess *MA) { |
1985 | 12.2k | if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA)) |
1986 | 12.1k | MUD->resetOptimized(); |
1987 | 12.2k | } |
1988 | | |
1989 | | /// \brief Walk the use-def chains starting at \p MA and find |
1990 | | /// the MemoryAccess that actually clobbers Loc. |
1991 | | /// |
1992 | | /// \returns our clobbering memory access |
1993 | | MemoryAccess *MemorySSA::CachingWalker::getClobberingMemoryAccess( |
1994 | 910k | MemoryAccess *StartingAccess, UpwardsMemoryQuery &Q) { |
1995 | 910k | MemoryAccess *New = Walker.findClobber(StartingAccess, Q); |
1996 | | #ifdef EXPENSIVE_CHECKS |
1997 | | MemoryAccess *NewNoCache = Walker.findClobber(StartingAccess, Q); |
1998 | | assert(NewNoCache == New && "Cache made us hand back a different result?"); |
1999 | | (void)NewNoCache; |
2000 | | #endif |
2001 | 910k | if (AutoResetWalker) |
2002 | 15.8k | resetClobberWalker(); |
2003 | 910k | return New; |
2004 | 910k | } |
2005 | | |
2006 | | MemoryAccess *MemorySSA::CachingWalker::getClobberingMemoryAccess( |
2007 | 2 | MemoryAccess *StartingAccess, const MemoryLocation &Loc) { |
2008 | 2 | if (isa<MemoryPhi>(StartingAccess)) |
2009 | 0 | return StartingAccess; |
2010 | 2 | |
2011 | 2 | auto *StartingUseOrDef = cast<MemoryUseOrDef>(StartingAccess); |
2012 | 2 | if (MSSA->isLiveOnEntryDef(StartingUseOrDef)) |
2013 | 0 | return StartingUseOrDef; |
2014 | 2 | |
2015 | 2 | Instruction *I = StartingUseOrDef->getMemoryInst(); |
2016 | 2 | |
2017 | 2 | // Conservatively, fences are always clobbers, so don't perform the walk if we |
2018 | 2 | // hit a fence. |
2019 | 2 | if (!ImmutableCallSite(I) && 2 I->isFenceLike()2 ) |
2020 | 0 | return StartingUseOrDef; |
2021 | 2 | |
2022 | 2 | UpwardsMemoryQuery Q; |
2023 | 2 | Q.OriginalAccess = StartingUseOrDef; |
2024 | 2 | Q.StartingLoc = Loc; |
2025 | 2 | Q.Inst = I; |
2026 | 2 | Q.IsCall = false; |
2027 | 2 | |
2028 | 2 | // Unlike the other function, do not walk to the def of a def, because we are |
2029 | 2 | // handed something we already believe is the clobbering access. |
2030 | 2 | MemoryAccess *DefiningAccess = isa<MemoryUse>(StartingUseOrDef) |
2031 | 0 | ? StartingUseOrDef->getDefiningAccess() |
2032 | 2 | : StartingUseOrDef; |
2033 | 2 | |
2034 | 2 | MemoryAccess *Clobber = getClobberingMemoryAccess(DefiningAccess, Q); |
2035 | 2 | DEBUG(dbgs() << "Starting Memory SSA clobber for " << *I << " is "); |
2036 | 2 | DEBUG(dbgs() << *StartingUseOrDef << "\n"); |
2037 | 2 | DEBUG(dbgs() << "Final Memory SSA clobber for " << *I << " is "); |
2038 | 2 | DEBUG(dbgs() << *Clobber << "\n"); |
2039 | 2 | return Clobber; |
2040 | 2 | } |
2041 | | |
2042 | | MemoryAccess * |
2043 | 1.27M | MemorySSA::CachingWalker::getClobberingMemoryAccess(MemoryAccess *MA) { |
2044 | 1.27M | auto *StartingAccess = dyn_cast<MemoryUseOrDef>(MA); |
2045 | 1.27M | // If this is a MemoryPhi, we can't do anything. |
2046 | 1.27M | if (!StartingAccess) |
2047 | 0 | return MA; |
2048 | 1.27M | |
2049 | 1.27M | // If this is an already optimized use or def, return the optimized result. |
2050 | 1.27M | // Note: Currently, we do not store the optimized def result because we'd need |
2051 | 1.27M | // a separate field, since we can't use it as the defining access. |
2052 | 1.27M | if (auto *1.27M MUD1.27M = dyn_cast<MemoryUseOrDef>(StartingAccess)) |
2053 | 1.27M | if (1.27M MUD->isOptimized()1.27M ) |
2054 | 365k | return MUD->getOptimized(); |
2055 | 910k | |
2056 | 910k | const Instruction *I = StartingAccess->getMemoryInst(); |
2057 | 910k | UpwardsMemoryQuery Q(I, StartingAccess); |
2058 | 910k | // We can't sanely do anything with a fences, they conservatively |
2059 | 910k | // clobber all memory, and have no locations to get pointers from to |
2060 | 910k | // try to disambiguate. |
2061 | 910k | if (!Q.IsCall && 910k I->isFenceLike()907k ) |
2062 | 0 | return StartingAccess; |
2063 | 910k | |
2064 | 910k | if (910k isUseTriviallyOptimizableToLiveOnEntry(*MSSA->AA, I)910k ) { |
2065 | 1 | MemoryAccess *LiveOnEntry = MSSA->getLiveOnEntryDef(); |
2066 | 1 | if (auto *MUD = dyn_cast<MemoryUseOrDef>(StartingAccess)) |
2067 | 1 | MUD->setOptimized(LiveOnEntry); |
2068 | 1 | return LiveOnEntry; |
2069 | 1 | } |
2070 | 910k | |
2071 | 910k | // Start with the thing we already think clobbers this location |
2072 | 910k | MemoryAccess *DefiningAccess = StartingAccess->getDefiningAccess(); |
2073 | 910k | |
2074 | 910k | // At this point, DefiningAccess may be the live on entry def. |
2075 | 910k | // If it is, we will not get a better result. |
2076 | 910k | if (MSSA->isLiveOnEntryDef(DefiningAccess)) |
2077 | 8 | return DefiningAccess; |
2078 | 910k | |
2079 | 910k | MemoryAccess *Result = getClobberingMemoryAccess(DefiningAccess, Q); |
2080 | 910k | DEBUG(dbgs() << "Starting Memory SSA clobber for " << *I << " is "); |
2081 | 910k | DEBUG(dbgs() << *DefiningAccess << "\n"); |
2082 | 910k | DEBUG(dbgs() << "Final Memory SSA clobber for " << *I << " is "); |
2083 | 910k | DEBUG(dbgs() << *Result << "\n"); |
2084 | 910k | if (auto *MUD = dyn_cast<MemoryUseOrDef>(StartingAccess)) |
2085 | 910k | MUD->setOptimized(Result); |
2086 | 1.27M | |
2087 | 1.27M | return Result; |
2088 | 1.27M | } |
2089 | | |
2090 | | MemoryAccess * |
2091 | 0 | DoNothingMemorySSAWalker::getClobberingMemoryAccess(MemoryAccess *MA) { |
2092 | 0 | if (auto *Use = dyn_cast<MemoryUseOrDef>(MA)) |
2093 | 0 | return Use->getDefiningAccess(); |
2094 | 0 | return MA; |
2095 | 0 | } |
2096 | | |
2097 | | MemoryAccess *DoNothingMemorySSAWalker::getClobberingMemoryAccess( |
2098 | 0 | MemoryAccess *StartingAccess, const MemoryLocation &) { |
2099 | 0 | if (auto *Use = dyn_cast<MemoryUseOrDef>(StartingAccess)) |
2100 | 0 | return Use->getDefiningAccess(); |
2101 | 0 | return StartingAccess; |
2102 | 0 | } |
2103 | | |
2104 | 0 | void MemoryPhi::deleteMe(DerivedUser *Self) { |
2105 | 0 | delete static_cast<MemoryPhi *>(Self); |
2106 | 0 | } |
2107 | | |
2108 | 0 | void MemoryDef::deleteMe(DerivedUser *Self) { |
2109 | 0 | delete static_cast<MemoryDef *>(Self); |
2110 | 0 | } |
2111 | | |
2112 | 0 | void MemoryUse::deleteMe(DerivedUser *Self) { |
2113 | 0 | delete static_cast<MemoryUse *>(Self); |
2114 | 0 | } |