Bug Summary

File:lib/Analysis/MemorySSA.cpp
Warning:line 1077, column 5
Value stored to 'Walker' is never read

Annotated Source Code

[?] Use j/k keys for keyboard navigation

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
57using namespace llvm;
58
59#define DEBUG_TYPE"memoryssa" "memoryssa"
60
61INITIALIZE_PASS_BEGIN(MemorySSAWrapperPass, "memoryssa", "Memory SSA", false,static void *initializeMemorySSAWrapperPassPassOnce(PassRegistry
&Registry) {
62 true)static void *initializeMemorySSAWrapperPassPassOnce(PassRegistry
&Registry) {
63INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);
64INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)initializeAAResultsWrapperPassPass(Registry);
65INITIALIZE_PASS_END(MemorySSAWrapperPass, "memoryssa", "Memory SSA", false,PassInfo *PI = new PassInfo( "Memory SSA", "memoryssa", &
MemorySSAWrapperPass::ID, PassInfo::NormalCtor_t(callDefaultCtor
<MemorySSAWrapperPass>), false, true); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeMemorySSAWrapperPassPassFlag
; void llvm::initializeMemorySSAWrapperPassPass(PassRegistry &
Registry) { llvm::call_once(InitializeMemorySSAWrapperPassPassFlag
, initializeMemorySSAWrapperPassPassOnce, std::ref(Registry))
; }
66 true)PassInfo *PI = new PassInfo( "Memory SSA", "memoryssa", &
MemorySSAWrapperPass::ID, PassInfo::NormalCtor_t(callDefaultCtor
<MemorySSAWrapperPass>), false, true); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeMemorySSAWrapperPassPassFlag
; void llvm::initializeMemorySSAWrapperPassPass(PassRegistry &
Registry) { llvm::call_once(InitializeMemorySSAWrapperPassPassFlag
, initializeMemorySSAWrapperPassPassOnce, std::ref(Registry))
; }
67
68INITIALIZE_PASS_BEGIN(MemorySSAPrinterLegacyPass, "print-memoryssa",static void *initializeMemorySSAPrinterLegacyPassPassOnce(PassRegistry
&Registry) {
69 "Memory SSA Printer", false, false)static void *initializeMemorySSAPrinterLegacyPassPassOnce(PassRegistry
&Registry) {
70INITIALIZE_PASS_DEPENDENCY(MemorySSAWrapperPass)initializeMemorySSAWrapperPassPass(Registry);
71INITIALIZE_PASS_END(MemorySSAPrinterLegacyPass, "print-memoryssa",PassInfo *PI = new PassInfo( "Memory SSA Printer", "print-memoryssa"
, &MemorySSAPrinterLegacyPass::ID, PassInfo::NormalCtor_t
(callDefaultCtor<MemorySSAPrinterLegacyPass>), false, false
); Registry.registerPass(*PI, true); return PI; } static llvm
::once_flag InitializeMemorySSAPrinterLegacyPassPassFlag; void
llvm::initializeMemorySSAPrinterLegacyPassPass(PassRegistry &
Registry) { llvm::call_once(InitializeMemorySSAPrinterLegacyPassPassFlag
, initializeMemorySSAPrinterLegacyPassPassOnce, std::ref(Registry
)); }
72 "Memory SSA Printer", false, false)PassInfo *PI = new PassInfo( "Memory SSA Printer", "print-memoryssa"
, &MemorySSAPrinterLegacyPass::ID, PassInfo::NormalCtor_t
(callDefaultCtor<MemorySSAPrinterLegacyPass>), false, false
); Registry.registerPass(*PI, true); return PI; } static llvm
::once_flag InitializeMemorySSAPrinterLegacyPassPassFlag; void
llvm::initializeMemorySSAPrinterLegacyPassPass(PassRegistry &
Registry) { llvm::call_once(InitializeMemorySSAPrinterLegacyPassPassFlag
, initializeMemorySSAPrinterLegacyPassPassOnce, std::ref(Registry
)); }
73
74static 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
79static cl::opt<bool>
80 VerifyMemorySSA("verify-memoryssa", cl::init(false), cl::Hidden,
81 cl::desc("Verify MemorySSA in legacy printer pass."));
82
83namespace llvm {
84
85/// \brief An assembly annotator class to print Memory SSA information in
86/// comments.
87class MemorySSAAnnotatedWriter : public AssemblyAnnotationWriter {
88 friend class MemorySSA;
89
90 const MemorySSA *MSSA;
91
92public:
93 MemorySSAAnnotatedWriter(const MemorySSA *M) : MSSA(M) {}
94
95 void emitBasicBlockStartAnnot(const BasicBlock *BB,
96 formatted_raw_ostream &OS) override {
97 if (MemoryAccess *MA = MSSA->getMemoryAccess(BB))
98 OS << "; " << *MA << "\n";
99 }
100
101 void emitInstructionAnnot(const Instruction *I,
102 formatted_raw_ostream &OS) override {
103 if (MemoryAccess *MA = MSSA->getMemoryAccess(I))
104 OS << "; " << *MA << "\n";
105 }
106};
107
108} // end namespace llvm
109
110namespace {
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.
117class MemoryLocOrCall {
118public:
119 bool IsCall = false;
120
121 MemoryLocOrCall() = default;
122 MemoryLocOrCall(MemoryUseOrDef *MUD)
123 : MemoryLocOrCall(MUD->getMemoryInst()) {}
124 MemoryLocOrCall(const MemoryUseOrDef *MUD)
125 : MemoryLocOrCall(MUD->getMemoryInst()) {}
126
127 MemoryLocOrCall(Instruction *Inst) {
128 if (ImmutableCallSite(Inst)) {
129 IsCall = true;
130 CS = ImmutableCallSite(Inst);
131 } else {
132 IsCall = false;
133 // There is no such thing as a memorylocation for a fence inst, and it is
134 // unique in that regard.
135 if (!isa<FenceInst>(Inst))
136 Loc = MemoryLocation::get(Inst);
137 }
138 }
139
140 explicit MemoryLocOrCall(const MemoryLocation &Loc) : Loc(Loc) {}
141
142 ImmutableCallSite getCS() const {
143 assert(IsCall)(static_cast <bool> (IsCall) ? void (0) : __assert_fail
("IsCall", "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 143, __extension__ __PRETTY_FUNCTION__))
;
144 return CS;
145 }
146
147 MemoryLocation getLoc() const {
148 assert(!IsCall)(static_cast <bool> (!IsCall) ? void (0) : __assert_fail
("!IsCall", "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 148, __extension__ __PRETTY_FUNCTION__))
;
149 return Loc;
150 }
151
152 bool operator==(const MemoryLocOrCall &Other) const {
153 if (IsCall != Other.IsCall)
154 return false;
155
156 if (IsCall)
157 return CS.getCalledValue() == Other.CS.getCalledValue();
158 return Loc == Other.Loc;
159 }
160
161private:
162 union {
163 ImmutableCallSite CS;
164 MemoryLocation Loc;
165 };
166};
167
168} // end anonymous namespace
169
170namespace llvm {
171
172template <> struct DenseMapInfo<MemoryLocOrCall> {
173 static inline MemoryLocOrCall getEmptyKey() {
174 return MemoryLocOrCall(DenseMapInfo<MemoryLocation>::getEmptyKey());
175 }
176
177 static inline MemoryLocOrCall getTombstoneKey() {
178 return MemoryLocOrCall(DenseMapInfo<MemoryLocation>::getTombstoneKey());
179 }
180
181 static unsigned getHashValue(const MemoryLocOrCall &MLOC) {
182 if (MLOC.IsCall)
183 return hash_combine(MLOC.IsCall,
184 DenseMapInfo<const Value *>::getHashValue(
185 MLOC.getCS().getCalledValue()));
186 return hash_combine(
187 MLOC.IsCall, DenseMapInfo<MemoryLocation>::getHashValue(MLOC.getLoc()));
188 }
189
190 static bool isEqual(const MemoryLocOrCall &LHS, const MemoryLocOrCall &RHS) {
191 return LHS == RHS;
192 }
193};
194
195} // end namespace llvm
196
197/// This does one-way checks to see if Use could theoretically be hoisted above
198/// MayClobber. This will not check the other way around.
199///
200/// This assumes that, for the purposes of MemorySSA, Use comes directly after
201/// MayClobber, with no potentially clobbering operations in between them.
202/// (Where potentially clobbering ops are memory barriers, aliased stores, etc.)
203static bool areLoadsReorderable(const LoadInst *Use,
204 const LoadInst *MayClobber) {
205 bool VolatileUse = Use->isVolatile();
206 bool VolatileClobber = MayClobber->isVolatile();
207 // Volatile operations may never be reordered with other volatile operations.
208 if (VolatileUse && VolatileClobber)
209 return false;
210 // Otherwise, volatile doesn't matter here. From the language reference:
211 // 'optimizers may change the order of volatile operations relative to
212 // non-volatile operations.'"
213
214 // If a load is seq_cst, it cannot be moved above other loads. If its ordering
215 // is weaker, it can be moved above other loads. We just need to be sure that
216 // MayClobber isn't an acquire load, because loads can't be moved above
217 // acquire loads.
218 //
219 // Note that this explicitly *does* allow the free reordering of monotonic (or
220 // weaker) loads of the same address.
221 bool SeqCstUse = Use->getOrdering() == AtomicOrdering::SequentiallyConsistent;
222 bool MayClobberIsAcquire = isAtLeastOrStrongerThan(MayClobber->getOrdering(),
223 AtomicOrdering::Acquire);
224 return !(SeqCstUse || MayClobberIsAcquire);
225}
226
227static bool instructionClobbersQuery(MemoryDef *MD,
228 const MemoryLocation &UseLoc,
229 const Instruction *UseInst,
230 AliasAnalysis &AA) {
231 Instruction *DefInst = MD->getMemoryInst();
232 assert(DefInst && "Defining instruction not actually an instruction")(static_cast <bool> (DefInst && "Defining instruction not actually an instruction"
) ? void (0) : __assert_fail ("DefInst && \"Defining instruction not actually an instruction\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 232, __extension__ __PRETTY_FUNCTION__))
;
233 ImmutableCallSite UseCS(UseInst);
234
235 if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(DefInst)) {
236 // These intrinsics will show up as affecting memory, but they are just
237 // markers.
238 switch (II->getIntrinsicID()) {
239 case Intrinsic::lifetime_start:
240 if (UseCS)
241 return false;
242 return AA.isMustAlias(MemoryLocation(II->getArgOperand(1)), UseLoc);
243 case Intrinsic::lifetime_end:
244 case Intrinsic::invariant_start:
245 case Intrinsic::invariant_end:
246 case Intrinsic::assume:
247 return false;
248 default:
249 break;
250 }
251 }
252
253 if (UseCS) {
254 ModRefInfo I = AA.getModRefInfo(DefInst, UseCS);
255 return isModOrRefSet(I);
256 }
257
258 if (auto *DefLoad = dyn_cast<LoadInst>(DefInst))
259 if (auto *UseLoad = dyn_cast<LoadInst>(UseInst))
260 return !areLoadsReorderable(UseLoad, DefLoad);
261
262 return isModSet(AA.getModRefInfo(DefInst, UseLoc));
263}
264
265static bool instructionClobbersQuery(MemoryDef *MD, const MemoryUseOrDef *MU,
266 const MemoryLocOrCall &UseMLOC,
267 AliasAnalysis &AA) {
268 // FIXME: This is a temporary hack to allow a single instructionClobbersQuery
269 // to exist while MemoryLocOrCall is pushed through places.
270 if (UseMLOC.IsCall)
271 return instructionClobbersQuery(MD, MemoryLocation(), MU->getMemoryInst(),
272 AA);
273 return instructionClobbersQuery(MD, UseMLOC.getLoc(), MU->getMemoryInst(),
274 AA);
275}
276
277// Return true when MD may alias MU, return false otherwise.
278bool MemorySSAUtil::defClobbersUseOrDef(MemoryDef *MD, const MemoryUseOrDef *MU,
279 AliasAnalysis &AA) {
280 return instructionClobbersQuery(MD, MU, MemoryLocOrCall(MU), AA);
281}
282
283namespace {
284
285struct UpwardsMemoryQuery {
286 // True if our original query started off as a call
287 bool IsCall = false;
288 // The pointer location we started the query with. This will be empty if
289 // IsCall is true.
290 MemoryLocation StartingLoc;
291 // This is the instruction we were querying about.
292 const Instruction *Inst = nullptr;
293 // The MemoryAccess we actually got called with, used to test local domination
294 const MemoryAccess *OriginalAccess = nullptr;
295
296 UpwardsMemoryQuery() = default;
297
298 UpwardsMemoryQuery(const Instruction *Inst, const MemoryAccess *Access)
299 : IsCall(ImmutableCallSite(Inst)), Inst(Inst), OriginalAccess(Access) {
300 if (!IsCall)
301 StartingLoc = MemoryLocation::get(Inst);
302 }
303};
304
305} // end anonymous namespace
306
307static bool lifetimeEndsAt(MemoryDef *MD, const MemoryLocation &Loc,
308 AliasAnalysis &AA) {
309 Instruction *Inst = MD->getMemoryInst();
310 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
311 switch (II->getIntrinsicID()) {
312 case Intrinsic::lifetime_end:
313 return AA.isMustAlias(MemoryLocation(II->getArgOperand(1)), Loc);
314 default:
315 return false;
316 }
317 }
318 return false;
319}
320
321static bool isUseTriviallyOptimizableToLiveOnEntry(AliasAnalysis &AA,
322 const Instruction *I) {
323 // If the memory can't be changed, then loads of the memory can't be
324 // clobbered.
325 //
326 // FIXME: We should handle invariant groups, as well. It's a bit harder,
327 // because we need to pay close attention to invariant group barriers.
328 return isa<LoadInst>(I) && (I->getMetadata(LLVMContext::MD_invariant_load) ||
329 AA.pointsToConstantMemory(cast<LoadInst>(I)->
330 getPointerOperand()));
331}
332
333/// Verifies that `Start` is clobbered by `ClobberAt`, and that nothing
334/// inbetween `Start` and `ClobberAt` can clobbers `Start`.
335///
336/// This is meant to be as simple and self-contained as possible. Because it
337/// uses no cache, etc., it can be relatively expensive.
338///
339/// \param Start The MemoryAccess that we want to walk from.
340/// \param ClobberAt A clobber for Start.
341/// \param StartLoc The MemoryLocation for Start.
342/// \param MSSA The MemorySSA isntance that Start and ClobberAt belong to.
343/// \param Query The UpwardsMemoryQuery we used for our search.
344/// \param AA The AliasAnalysis we used for our search.
345static void LLVM_ATTRIBUTE_UNUSED__attribute__((__unused__))
346checkClobberSanity(MemoryAccess *Start, MemoryAccess *ClobberAt,
347 const MemoryLocation &StartLoc, const MemorySSA &MSSA,
348 const UpwardsMemoryQuery &Query, AliasAnalysis &AA) {
349 assert(MSSA.dominates(ClobberAt, Start) && "Clobber doesn't dominate start?")(static_cast <bool> (MSSA.dominates(ClobberAt, Start) &&
"Clobber doesn't dominate start?") ? void (0) : __assert_fail
("MSSA.dominates(ClobberAt, Start) && \"Clobber doesn't dominate start?\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 349, __extension__ __PRETTY_FUNCTION__))
;
350
351 if (MSSA.isLiveOnEntryDef(Start)) {
352 assert(MSSA.isLiveOnEntryDef(ClobberAt) &&(static_cast <bool> (MSSA.isLiveOnEntryDef(ClobberAt) &&
"liveOnEntry must clobber itself") ? void (0) : __assert_fail
("MSSA.isLiveOnEntryDef(ClobberAt) && \"liveOnEntry must clobber itself\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 353, __extension__ __PRETTY_FUNCTION__))
353 "liveOnEntry must clobber itself")(static_cast <bool> (MSSA.isLiveOnEntryDef(ClobberAt) &&
"liveOnEntry must clobber itself") ? void (0) : __assert_fail
("MSSA.isLiveOnEntryDef(ClobberAt) && \"liveOnEntry must clobber itself\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 353, __extension__ __PRETTY_FUNCTION__))
;
354 return;
355 }
356
357 bool FoundClobber = false;
358 DenseSet<MemoryAccessPair> VisitedPhis;
359 SmallVector<MemoryAccessPair, 8> Worklist;
360 Worklist.emplace_back(Start, StartLoc);
361 // Walk all paths from Start to ClobberAt, while looking for clobbers. If one
362 // is found, complain.
363 while (!Worklist.empty()) {
364 MemoryAccessPair MAP = Worklist.pop_back_val();
365 // All we care about is that nothing from Start to ClobberAt clobbers Start.
366 // We learn nothing from revisiting nodes.
367 if (!VisitedPhis.insert(MAP).second)
368 continue;
369
370 for (MemoryAccess *MA : def_chain(MAP.first)) {
371 if (MA == ClobberAt) {
372 if (auto *MD = dyn_cast<MemoryDef>(MA)) {
373 // instructionClobbersQuery isn't essentially free, so don't use `|=`,
374 // since it won't let us short-circuit.
375 //
376 // Also, note that this can't be hoisted out of the `Worklist` loop,
377 // since MD may only act as a clobber for 1 of N MemoryLocations.
378 FoundClobber =
379 FoundClobber || MSSA.isLiveOnEntryDef(MD) ||
380 instructionClobbersQuery(MD, MAP.second, Query.Inst, AA);
381 }
382 break;
383 }
384
385 // We should never hit liveOnEntry, unless it's the clobber.
386 assert(!MSSA.isLiveOnEntryDef(MA) && "Hit liveOnEntry before clobber?")(static_cast <bool> (!MSSA.isLiveOnEntryDef(MA) &&
"Hit liveOnEntry before clobber?") ? void (0) : __assert_fail
("!MSSA.isLiveOnEntryDef(MA) && \"Hit liveOnEntry before clobber?\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 386, __extension__ __PRETTY_FUNCTION__))
;
387
388 if (auto *MD = dyn_cast<MemoryDef>(MA)) {
389 (void)MD;
390 assert(!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA) &&(static_cast <bool> (!instructionClobbersQuery(MD, MAP.
second, Query.Inst, AA) && "Found clobber before reaching ClobberAt!"
) ? void (0) : __assert_fail ("!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA) && \"Found clobber before reaching ClobberAt!\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 391, __extension__ __PRETTY_FUNCTION__))
391 "Found clobber before reaching ClobberAt!")(static_cast <bool> (!instructionClobbersQuery(MD, MAP.
second, Query.Inst, AA) && "Found clobber before reaching ClobberAt!"
) ? void (0) : __assert_fail ("!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA) && \"Found clobber before reaching ClobberAt!\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 391, __extension__ __PRETTY_FUNCTION__))
;
392 continue;
393 }
394
395 assert(isa<MemoryPhi>(MA))(static_cast <bool> (isa<MemoryPhi>(MA)) ? void (
0) : __assert_fail ("isa<MemoryPhi>(MA)", "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 395, __extension__ __PRETTY_FUNCTION__))
;
396 Worklist.append(upward_defs_begin({MA, MAP.second}), upward_defs_end());
397 }
398 }
399
400 // If ClobberAt is a MemoryPhi, we can assume something above it acted as a
401 // clobber. Otherwise, `ClobberAt` should've acted as a clobber at some point.
402 assert((isa<MemoryPhi>(ClobberAt) || FoundClobber) &&(static_cast <bool> ((isa<MemoryPhi>(ClobberAt) ||
FoundClobber) && "ClobberAt never acted as a clobber"
) ? void (0) : __assert_fail ("(isa<MemoryPhi>(ClobberAt) || FoundClobber) && \"ClobberAt never acted as a clobber\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 403, __extension__ __PRETTY_FUNCTION__))
403 "ClobberAt never acted as a clobber")(static_cast <bool> ((isa<MemoryPhi>(ClobberAt) ||
FoundClobber) && "ClobberAt never acted as a clobber"
) ? void (0) : __assert_fail ("(isa<MemoryPhi>(ClobberAt) || FoundClobber) && \"ClobberAt never acted as a clobber\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 403, __extension__ __PRETTY_FUNCTION__))
;
404}
405
406namespace {
407
408/// Our algorithm for walking (and trying to optimize) clobbers, all wrapped up
409/// in one class.
410class ClobberWalker {
411 /// Save a few bytes by using unsigned instead of size_t.
412 using ListIndex = unsigned;
413
414 /// Represents a span of contiguous MemoryDefs, potentially ending in a
415 /// MemoryPhi.
416 struct DefPath {
417 MemoryLocation Loc;
418 // Note that, because we always walk in reverse, Last will always dominate
419 // First. Also note that First and Last are inclusive.
420 MemoryAccess *First;
421 MemoryAccess *Last;
422 Optional<ListIndex> Previous;
423
424 DefPath(const MemoryLocation &Loc, MemoryAccess *First, MemoryAccess *Last,
425 Optional<ListIndex> Previous)
426 : Loc(Loc), First(First), Last(Last), Previous(Previous) {}
427
428 DefPath(const MemoryLocation &Loc, MemoryAccess *Init,
429 Optional<ListIndex> Previous)
430 : DefPath(Loc, Init, Init, Previous) {}
431 };
432
433 const MemorySSA &MSSA;
434 AliasAnalysis &AA;
435 DominatorTree &DT;
436 UpwardsMemoryQuery *Query;
437
438 // Phi optimization bookkeeping
439 SmallVector<DefPath, 32> Paths;
440 DenseSet<ConstMemoryAccessPair> VisitedPhis;
441
442 /// Find the nearest def or phi that `From` can legally be optimized to.
443 const MemoryAccess *getWalkTarget(const MemoryPhi *From) const {
444 assert(From->getNumOperands() && "Phi with no operands?")(static_cast <bool> (From->getNumOperands() &&
"Phi with no operands?") ? void (0) : __assert_fail ("From->getNumOperands() && \"Phi with no operands?\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 444, __extension__ __PRETTY_FUNCTION__))
;
445
446 BasicBlock *BB = From->getBlock();
447 MemoryAccess *Result = MSSA.getLiveOnEntryDef();
448 DomTreeNode *Node = DT.getNode(BB);
449 while ((Node = Node->getIDom())) {
450 auto *Defs = MSSA.getBlockDefs(Node->getBlock());
451 if (Defs)
452 return &*Defs->rbegin();
453 }
454 return Result;
455 }
456
457 /// Result of calling walkToPhiOrClobber.
458 struct UpwardsWalkResult {
459 /// The "Result" of the walk. Either a clobber, the last thing we walked, or
460 /// both.
461 MemoryAccess *Result;
462 bool IsKnownClobber;
463 };
464
465 /// Walk to the next Phi or Clobber in the def chain starting at Desc.Last.
466 /// This will update Desc.Last as it walks. It will (optionally) also stop at
467 /// StopAt.
468 ///
469 /// This does not test for whether StopAt is a clobber
470 UpwardsWalkResult
471 walkToPhiOrClobber(DefPath &Desc,
472 const MemoryAccess *StopAt = nullptr) const {
473 assert(!isa<MemoryUse>(Desc.Last) && "Uses don't exist in my world")(static_cast <bool> (!isa<MemoryUse>(Desc.Last) &&
"Uses don't exist in my world") ? void (0) : __assert_fail (
"!isa<MemoryUse>(Desc.Last) && \"Uses don't exist in my world\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 473, __extension__ __PRETTY_FUNCTION__))
;
474
475 for (MemoryAccess *Current : def_chain(Desc.Last)) {
476 Desc.Last = Current;
477 if (Current == StopAt)
478 return {Current, false};
479
480 if (auto *MD = dyn_cast<MemoryDef>(Current))
481 if (MSSA.isLiveOnEntryDef(MD) ||
482 instructionClobbersQuery(MD, Desc.Loc, Query->Inst, AA))
483 return {MD, true};
484 }
485
486 assert(isa<MemoryPhi>(Desc.Last) &&(static_cast <bool> (isa<MemoryPhi>(Desc.Last) &&
"Ended at a non-clobber that's not a phi?") ? void (0) : __assert_fail
("isa<MemoryPhi>(Desc.Last) && \"Ended at a non-clobber that's not a phi?\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 487, __extension__ __PRETTY_FUNCTION__))
487 "Ended at a non-clobber that's not a phi?")(static_cast <bool> (isa<MemoryPhi>(Desc.Last) &&
"Ended at a non-clobber that's not a phi?") ? void (0) : __assert_fail
("isa<MemoryPhi>(Desc.Last) && \"Ended at a non-clobber that's not a phi?\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 487, __extension__ __PRETTY_FUNCTION__))
;
488 return {Desc.Last, false};
489 }
490
491 void addSearches(MemoryPhi *Phi, SmallVectorImpl<ListIndex> &PausedSearches,
492 ListIndex PriorNode) {
493 auto UpwardDefs = make_range(upward_defs_begin({Phi, Paths[PriorNode].Loc}),
494 upward_defs_end());
495 for (const MemoryAccessPair &P : UpwardDefs) {
496 PausedSearches.push_back(Paths.size());
497 Paths.emplace_back(P.second, P.first, PriorNode);
498 }
499 }
500
501 /// Represents a search that terminated after finding a clobber. This clobber
502 /// may or may not be present in the path of defs from LastNode..SearchStart,
503 /// since it may have been retrieved from cache.
504 struct TerminatedPath {
505 MemoryAccess *Clobber;
506 ListIndex LastNode;
507 };
508
509 /// Get an access that keeps us from optimizing to the given phi.
510 ///
511 /// PausedSearches is an array of indices into the Paths array. Its incoming
512 /// value is the indices of searches that stopped at the last phi optimization
513 /// target. It's left in an unspecified state.
514 ///
515 /// If this returns None, NewPaused is a vector of searches that terminated
516 /// at StopWhere. Otherwise, NewPaused is left in an unspecified state.
517 Optional<TerminatedPath>
518 getBlockingAccess(const MemoryAccess *StopWhere,
519 SmallVectorImpl<ListIndex> &PausedSearches,
520 SmallVectorImpl<ListIndex> &NewPaused,
521 SmallVectorImpl<TerminatedPath> &Terminated) {
522 assert(!PausedSearches.empty() && "No searches to continue?")(static_cast <bool> (!PausedSearches.empty() &&
"No searches to continue?") ? void (0) : __assert_fail ("!PausedSearches.empty() && \"No searches to continue?\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 522, __extension__ __PRETTY_FUNCTION__))
;
523
524 // BFS vs DFS really doesn't make a difference here, so just do a DFS with
525 // PausedSearches as our stack.
526 while (!PausedSearches.empty()) {
527 ListIndex PathIndex = PausedSearches.pop_back_val();
528 DefPath &Node = Paths[PathIndex];
529
530 // If we've already visited this path with this MemoryLocation, we don't
531 // need to do so again.
532 //
533 // NOTE: That we just drop these paths on the ground makes caching
534 // behavior sporadic. e.g. given a diamond:
535 // A
536 // B C
537 // D
538 //
539 // ...If we walk D, B, A, C, we'll only cache the result of phi
540 // optimization for A, B, and D; C will be skipped because it dies here.
541 // This arguably isn't the worst thing ever, since:
542 // - We generally query things in a top-down order, so if we got below D
543 // without needing cache entries for {C, MemLoc}, then chances are
544 // that those cache entries would end up ultimately unused.
545 // - We still cache things for A, so C only needs to walk up a bit.
546 // If this behavior becomes problematic, we can fix without a ton of extra
547 // work.
548 if (!VisitedPhis.insert({Node.Last, Node.Loc}).second)
549 continue;
550
551 UpwardsWalkResult Res = walkToPhiOrClobber(Node, /*StopAt=*/StopWhere);
552 if (Res.IsKnownClobber) {
553 assert(Res.Result != StopWhere)(static_cast <bool> (Res.Result != StopWhere) ? void (0
) : __assert_fail ("Res.Result != StopWhere", "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 553, __extension__ __PRETTY_FUNCTION__))
;
554 // If this wasn't a cache hit, we hit a clobber when walking. That's a
555 // failure.
556 TerminatedPath Term{Res.Result, PathIndex};
557 if (!MSSA.dominates(Res.Result, StopWhere))
558 return Term;
559
560 // Otherwise, it's a valid thing to potentially optimize to.
561 Terminated.push_back(Term);
562 continue;
563 }
564
565 if (Res.Result == StopWhere) {
566 // We've hit our target. Save this path off for if we want to continue
567 // walking.
568 NewPaused.push_back(PathIndex);
569 continue;
570 }
571
572 assert(!MSSA.isLiveOnEntryDef(Res.Result) && "liveOnEntry is a clobber")(static_cast <bool> (!MSSA.isLiveOnEntryDef(Res.Result)
&& "liveOnEntry is a clobber") ? void (0) : __assert_fail
("!MSSA.isLiveOnEntryDef(Res.Result) && \"liveOnEntry is a clobber\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 572, __extension__ __PRETTY_FUNCTION__))
;
573 addSearches(cast<MemoryPhi>(Res.Result), PausedSearches, PathIndex);
574 }
575
576 return None;
577 }
578
579 template <typename T, typename Walker>
580 struct generic_def_path_iterator
581 : public iterator_facade_base<generic_def_path_iterator<T, Walker>,
582 std::forward_iterator_tag, T *> {
583 generic_def_path_iterator() = default;
584 generic_def_path_iterator(Walker *W, ListIndex N) : W(W), N(N) {}
585
586 T &operator*() const { return curNode(); }
587
588 generic_def_path_iterator &operator++() {
589 N = curNode().Previous;
590 return *this;
591 }
592
593 bool operator==(const generic_def_path_iterator &O) const {
594 if (N.hasValue() != O.N.hasValue())
595 return false;
596 return !N.hasValue() || *N == *O.N;
597 }
598
599 private:
600 T &curNode() const { return W->Paths[*N]; }
601
602 Walker *W = nullptr;
603 Optional<ListIndex> N = None;
604 };
605
606 using def_path_iterator = generic_def_path_iterator<DefPath, ClobberWalker>;
607 using const_def_path_iterator =
608 generic_def_path_iterator<const DefPath, const ClobberWalker>;
609
610 iterator_range<def_path_iterator> def_path(ListIndex From) {
611 return make_range(def_path_iterator(this, From), def_path_iterator());
612 }
613
614 iterator_range<const_def_path_iterator> const_def_path(ListIndex From) const {
615 return make_range(const_def_path_iterator(this, From),
616 const_def_path_iterator());
617 }
618
619 struct OptznResult {
620 /// The path that contains our result.
621 TerminatedPath PrimaryClobber;
622 /// The paths that we can legally cache back from, but that aren't
623 /// necessarily the result of the Phi optimization.
624 SmallVector<TerminatedPath, 4> OtherClobbers;
625 };
626
627 ListIndex defPathIndex(const DefPath &N) const {
628 // The assert looks nicer if we don't need to do &N
629 const DefPath *NP = &N;
630 assert(!Paths.empty() && NP >= &Paths.front() && NP <= &Paths.back() &&(static_cast <bool> (!Paths.empty() && NP >=
&Paths.front() && NP <= &Paths.back() &&
"Out of bounds DefPath!") ? void (0) : __assert_fail ("!Paths.empty() && NP >= &Paths.front() && NP <= &Paths.back() && \"Out of bounds DefPath!\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 631, __extension__ __PRETTY_FUNCTION__))
631 "Out of bounds DefPath!")(static_cast <bool> (!Paths.empty() && NP >=
&Paths.front() && NP <= &Paths.back() &&
"Out of bounds DefPath!") ? void (0) : __assert_fail ("!Paths.empty() && NP >= &Paths.front() && NP <= &Paths.back() && \"Out of bounds DefPath!\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 631, __extension__ __PRETTY_FUNCTION__))
;
632 return NP - &Paths.front();
633 }
634
635 /// Try to optimize a phi as best as we can. Returns a SmallVector of Paths
636 /// that act as legal clobbers. Note that this won't return *all* clobbers.
637 ///
638 /// Phi optimization algorithm tl;dr:
639 /// - Find the earliest def/phi, A, we can optimize to
640 /// - Find if all paths from the starting memory access ultimately reach A
641 /// - If not, optimization isn't possible.
642 /// - Otherwise, walk from A to another clobber or phi, A'.
643 /// - If A' is a def, we're done.
644 /// - If A' is a phi, try to optimize it.
645 ///
646 /// A path is a series of {MemoryAccess, MemoryLocation} pairs. A path
647 /// terminates when a MemoryAccess that clobbers said MemoryLocation is found.
648 OptznResult tryOptimizePhi(MemoryPhi *Phi, MemoryAccess *Start,
649 const MemoryLocation &Loc) {
650 assert(Paths.empty() && VisitedPhis.empty() &&(static_cast <bool> (Paths.empty() && VisitedPhis
.empty() && "Reset the optimization state.") ? void (
0) : __assert_fail ("Paths.empty() && VisitedPhis.empty() && \"Reset the optimization state.\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 651, __extension__ __PRETTY_FUNCTION__))
651 "Reset the optimization state.")(static_cast <bool> (Paths.empty() && VisitedPhis
.empty() && "Reset the optimization state.") ? void (
0) : __assert_fail ("Paths.empty() && VisitedPhis.empty() && \"Reset the optimization state.\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 651, __extension__ __PRETTY_FUNCTION__))
;
652
653 Paths.emplace_back(Loc, Start, Phi, None);
654 // Stores how many "valid" optimization nodes we had prior to calling
655 // addSearches/getBlockingAccess. Necessary for caching if we had a blocker.
656 auto PriorPathsSize = Paths.size();
657
658 SmallVector<ListIndex, 16> PausedSearches;
659 SmallVector<ListIndex, 8> NewPaused;
660 SmallVector<TerminatedPath, 4> TerminatedPaths;
661
662 addSearches(Phi, PausedSearches, 0);
663
664 // Moves the TerminatedPath with the "most dominated" Clobber to the end of
665 // Paths.
666 auto MoveDominatedPathToEnd = [&](SmallVectorImpl<TerminatedPath> &Paths) {
667 assert(!Paths.empty() && "Need a path to move")(static_cast <bool> (!Paths.empty() && "Need a path to move"
) ? void (0) : __assert_fail ("!Paths.empty() && \"Need a path to move\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 667, __extension__ __PRETTY_FUNCTION__))
;
668 auto Dom = Paths.begin();
669 for (auto I = std::next(Dom), E = Paths.end(); I != E; ++I)
670 if (!MSSA.dominates(I->Clobber, Dom->Clobber))
671 Dom = I;
672 auto Last = Paths.end() - 1;
673 if (Last != Dom)
674 std::iter_swap(Last, Dom);
675 };
676
677 MemoryPhi *Current = Phi;
678 while (true) {
679 assert(!MSSA.isLiveOnEntryDef(Current) &&(static_cast <bool> (!MSSA.isLiveOnEntryDef(Current) &&
"liveOnEntry wasn't treated as a clobber?") ? void (0) : __assert_fail
("!MSSA.isLiveOnEntryDef(Current) && \"liveOnEntry wasn't treated as a clobber?\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 680, __extension__ __PRETTY_FUNCTION__))
680 "liveOnEntry wasn't treated as a clobber?")(static_cast <bool> (!MSSA.isLiveOnEntryDef(Current) &&
"liveOnEntry wasn't treated as a clobber?") ? void (0) : __assert_fail
("!MSSA.isLiveOnEntryDef(Current) && \"liveOnEntry wasn't treated as a clobber?\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 680, __extension__ __PRETTY_FUNCTION__))
;
681
682 const auto *Target = getWalkTarget(Current);
683 // If a TerminatedPath doesn't dominate Target, then it wasn't a legal
684 // optimization for the prior phi.
685 assert(all_of(TerminatedPaths, [&](const TerminatedPath &P) {(static_cast <bool> (all_of(TerminatedPaths, [&](const
TerminatedPath &P) { return MSSA.dominates(P.Clobber, Target
); })) ? void (0) : __assert_fail ("all_of(TerminatedPaths, [&](const TerminatedPath &P) { return MSSA.dominates(P.Clobber, Target); })"
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 687, __extension__ __PRETTY_FUNCTION__))
686 return MSSA.dominates(P.Clobber, Target);(static_cast <bool> (all_of(TerminatedPaths, [&](const
TerminatedPath &P) { return MSSA.dominates(P.Clobber, Target
); })) ? void (0) : __assert_fail ("all_of(TerminatedPaths, [&](const TerminatedPath &P) { return MSSA.dominates(P.Clobber, Target); })"
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 687, __extension__ __PRETTY_FUNCTION__))
687 }))(static_cast <bool> (all_of(TerminatedPaths, [&](const
TerminatedPath &P) { return MSSA.dominates(P.Clobber, Target
); })) ? void (0) : __assert_fail ("all_of(TerminatedPaths, [&](const TerminatedPath &P) { return MSSA.dominates(P.Clobber, Target); })"
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 687, __extension__ __PRETTY_FUNCTION__))
;
688
689 // FIXME: This is broken, because the Blocker may be reported to be
690 // liveOnEntry, and we'll happily wait for that to disappear (read: never)
691 // For the moment, this is fine, since we do nothing with blocker info.
692 if (Optional<TerminatedPath> Blocker = getBlockingAccess(
693 Target, PausedSearches, NewPaused, TerminatedPaths)) {
694
695 // Find the node we started at. We can't search based on N->Last, since
696 // we may have gone around a loop with a different MemoryLocation.
697 auto Iter = find_if(def_path(Blocker->LastNode), [&](const DefPath &N) {
698 return defPathIndex(N) < PriorPathsSize;
699 });
700 assert(Iter != def_path_iterator())(static_cast <bool> (Iter != def_path_iterator()) ? void
(0) : __assert_fail ("Iter != def_path_iterator()", "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 700, __extension__ __PRETTY_FUNCTION__))
;
701
702 DefPath &CurNode = *Iter;
703 assert(CurNode.Last == Current)(static_cast <bool> (CurNode.Last == Current) ? void (0
) : __assert_fail ("CurNode.Last == Current", "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 703, __extension__ __PRETTY_FUNCTION__))
;
704
705 // Two things:
706 // A. We can't reliably cache all of NewPaused back. Consider a case
707 // where we have two paths in NewPaused; one of which can't optimize
708 // above this phi, whereas the other can. If we cache the second path
709 // back, we'll end up with suboptimal cache entries. We can handle
710 // cases like this a bit better when we either try to find all
711 // clobbers that block phi optimization, or when our cache starts
712 // supporting unfinished searches.
713 // B. We can't reliably cache TerminatedPaths back here without doing
714 // extra checks; consider a case like:
715 // T
716 // / \
717 // D C
718 // \ /
719 // S
720 // Where T is our target, C is a node with a clobber on it, D is a
721 // diamond (with a clobber *only* on the left or right node, N), and
722 // S is our start. Say we walk to D, through the node opposite N
723 // (read: ignoring the clobber), and see a cache entry in the top
724 // node of D. That cache entry gets put into TerminatedPaths. We then
725 // walk up to C (N is later in our worklist), find the clobber, and
726 // quit. If we append TerminatedPaths to OtherClobbers, we'll cache
727 // the bottom part of D to the cached clobber, ignoring the clobber
728 // in N. Again, this problem goes away if we start tracking all
729 // blockers for a given phi optimization.
730 TerminatedPath Result{CurNode.Last, defPathIndex(CurNode)};
731 return {Result, {}};
732 }
733
734 // If there's nothing left to search, then all paths led to valid clobbers
735 // that we got from our cache; pick the nearest to the start, and allow
736 // the rest to be cached back.
737 if (NewPaused.empty()) {
738 MoveDominatedPathToEnd(TerminatedPaths);
739 TerminatedPath Result = TerminatedPaths.pop_back_val();
740 return {Result, std::move(TerminatedPaths)};
741 }
742
743 MemoryAccess *DefChainEnd = nullptr;
744 SmallVector<TerminatedPath, 4> Clobbers;
745 for (ListIndex Paused : NewPaused) {
746 UpwardsWalkResult WR = walkToPhiOrClobber(Paths[Paused]);
747 if (WR.IsKnownClobber)
748 Clobbers.push_back({WR.Result, Paused});
749 else
750 // Micro-opt: If we hit the end of the chain, save it.
751 DefChainEnd = WR.Result;
752 }
753
754 if (!TerminatedPaths.empty()) {
755 // If we couldn't find the dominating phi/liveOnEntry in the above loop,
756 // do it now.
757 if (!DefChainEnd)
758 for (auto *MA : def_chain(const_cast<MemoryAccess *>(Target)))
759 DefChainEnd = MA;
760
761 // If any of the terminated paths don't dominate the phi we'll try to
762 // optimize, we need to figure out what they are and quit.
763 const BasicBlock *ChainBB = DefChainEnd->getBlock();
764 for (const TerminatedPath &TP : TerminatedPaths) {
765 // Because we know that DefChainEnd is as "high" as we can go, we
766 // don't need local dominance checks; BB dominance is sufficient.
767 if (DT.dominates(ChainBB, TP.Clobber->getBlock()))
768 Clobbers.push_back(TP);
769 }
770 }
771
772 // If we have clobbers in the def chain, find the one closest to Current
773 // and quit.
774 if (!Clobbers.empty()) {
775 MoveDominatedPathToEnd(Clobbers);
776 TerminatedPath Result = Clobbers.pop_back_val();
777 return {Result, std::move(Clobbers)};
778 }
779
780 assert(all_of(NewPaused,(static_cast <bool> (all_of(NewPaused, [&](ListIndex
I) { return Paths[I].Last == DefChainEnd; })) ? void (0) : __assert_fail
("all_of(NewPaused, [&](ListIndex I) { return Paths[I].Last == DefChainEnd; })"
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 781, __extension__ __PRETTY_FUNCTION__))
781 [&](ListIndex I) { return Paths[I].Last == DefChainEnd; }))(static_cast <bool> (all_of(NewPaused, [&](ListIndex
I) { return Paths[I].Last == DefChainEnd; })) ? void (0) : __assert_fail
("all_of(NewPaused, [&](ListIndex I) { return Paths[I].Last == DefChainEnd; })"
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 781, __extension__ __PRETTY_FUNCTION__))
;
782
783 // Because liveOnEntry is a clobber, this must be a phi.
784 auto *DefChainPhi = cast<MemoryPhi>(DefChainEnd);
785
786 PriorPathsSize = Paths.size();
787 PausedSearches.clear();
788 for (ListIndex I : NewPaused)
789 addSearches(DefChainPhi, PausedSearches, I);
790 NewPaused.clear();
791
792 Current = DefChainPhi;
793 }
794 }
795
796 void verifyOptResult(const OptznResult &R) const {
797 assert(all_of(R.OtherClobbers, [&](const TerminatedPath &P) {(static_cast <bool> (all_of(R.OtherClobbers, [&](const
TerminatedPath &P) { return MSSA.dominates(P.Clobber, R.
PrimaryClobber.Clobber); })) ? void (0) : __assert_fail ("all_of(R.OtherClobbers, [&](const TerminatedPath &P) { return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber); })"
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 799, __extension__ __PRETTY_FUNCTION__))
798 return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber);(static_cast <bool> (all_of(R.OtherClobbers, [&](const
TerminatedPath &P) { return MSSA.dominates(P.Clobber, R.
PrimaryClobber.Clobber); })) ? void (0) : __assert_fail ("all_of(R.OtherClobbers, [&](const TerminatedPath &P) { return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber); })"
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 799, __extension__ __PRETTY_FUNCTION__))
799 }))(static_cast <bool> (all_of(R.OtherClobbers, [&](const
TerminatedPath &P) { return MSSA.dominates(P.Clobber, R.
PrimaryClobber.Clobber); })) ? void (0) : __assert_fail ("all_of(R.OtherClobbers, [&](const TerminatedPath &P) { return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber); })"
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 799, __extension__ __PRETTY_FUNCTION__))
;
800 }
801
802 void resetPhiOptznState() {
803 Paths.clear();
804 VisitedPhis.clear();
805 }
806
807public:
808 ClobberWalker(const MemorySSA &MSSA, AliasAnalysis &AA, DominatorTree &DT)
809 : MSSA(MSSA), AA(AA), DT(DT) {}
810
811 void reset() {}
812
813 /// Finds the nearest clobber for the given query, optimizing phis if
814 /// possible.
815 MemoryAccess *findClobber(MemoryAccess *Start, UpwardsMemoryQuery &Q) {
816 Query = &Q;
817
818 MemoryAccess *Current = Start;
819 // This walker pretends uses don't exist. If we're handed one, silently grab
820 // its def. (This has the nice side-effect of ensuring we never cache uses)
821 if (auto *MU = dyn_cast<MemoryUse>(Start))
822 Current = MU->getDefiningAccess();
823
824 DefPath FirstDesc(Q.StartingLoc, Current, Current, None);
825 // Fast path for the overly-common case (no crazy phi optimization
826 // necessary)
827 UpwardsWalkResult WalkResult = walkToPhiOrClobber(FirstDesc);
828 MemoryAccess *Result;
829 if (WalkResult.IsKnownClobber) {
830 Result = WalkResult.Result;
831 } else {
832 OptznResult OptRes = tryOptimizePhi(cast<MemoryPhi>(FirstDesc.Last),
833 Current, Q.StartingLoc);
834 verifyOptResult(OptRes);
835 resetPhiOptznState();
836 Result = OptRes.PrimaryClobber.Clobber;
837 }
838
839#ifdef EXPENSIVE_CHECKS
840 checkClobberSanity(Current, Result, Q.StartingLoc, MSSA, Q, AA);
841#endif
842 return Result;
843 }
844
845 void verify(const MemorySSA *MSSA) { assert(MSSA == &this->MSSA)(static_cast <bool> (MSSA == &this->MSSA) ? void
(0) : __assert_fail ("MSSA == &this->MSSA", "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 845, __extension__ __PRETTY_FUNCTION__))
; }
846};
847
848struct RenamePassData {
849 DomTreeNode *DTN;
850 DomTreeNode::const_iterator ChildIt;
851 MemoryAccess *IncomingVal;
852
853 RenamePassData(DomTreeNode *D, DomTreeNode::const_iterator It,
854 MemoryAccess *M)
855 : DTN(D), ChildIt(It), IncomingVal(M) {}
856
857 void swap(RenamePassData &RHS) {
858 std::swap(DTN, RHS.DTN);
859 std::swap(ChildIt, RHS.ChildIt);
860 std::swap(IncomingVal, RHS.IncomingVal);
861 }
862};
863
864} // end anonymous namespace
865
866namespace llvm {
867
868/// \brief A MemorySSAWalker that does AA walks to disambiguate accesses. It no
869/// longer does caching on its own,
870/// but the name has been retained for the moment.
871class MemorySSA::CachingWalker final : public MemorySSAWalker {
872 ClobberWalker Walker;
873 bool AutoResetWalker = true;
874
875 MemoryAccess *getClobberingMemoryAccess(MemoryAccess *, UpwardsMemoryQuery &);
876
877public:
878 CachingWalker(MemorySSA *, AliasAnalysis *, DominatorTree *);
879 ~CachingWalker() override = default;
880
881 using MemorySSAWalker::getClobberingMemoryAccess;
882
883 MemoryAccess *getClobberingMemoryAccess(MemoryAccess *) override;
884 MemoryAccess *getClobberingMemoryAccess(MemoryAccess *,
885 const MemoryLocation &) override;
886 void invalidateInfo(MemoryAccess *) override;
887
888 /// Whether we call resetClobberWalker() after each time we *actually* walk to
889 /// answer a clobber query.
890 void setAutoResetWalker(bool AutoReset) { AutoResetWalker = AutoReset; }
891
892 /// Drop the walker's persistent data structures.
893 void resetClobberWalker() { Walker.reset(); }
894
895 void verify(const MemorySSA *MSSA) override {
896 MemorySSAWalker::verify(MSSA);
897 Walker.verify(MSSA);
898 }
899};
900
901} // end namespace llvm
902
903void MemorySSA::renameSuccessorPhis(BasicBlock *BB, MemoryAccess *IncomingVal,
904 bool RenameAllUses) {
905 // Pass through values to our successors
906 for (const BasicBlock *S : successors(BB)) {
907 auto It = PerBlockAccesses.find(S);
908 // Rename the phi nodes in our successor block
909 if (It == PerBlockAccesses.end() || !isa<MemoryPhi>(It->second->front()))
910 continue;
911 AccessList *Accesses = It->second.get();
912 auto *Phi = cast<MemoryPhi>(&Accesses->front());
913 if (RenameAllUses) {
914 int PhiIndex = Phi->getBasicBlockIndex(BB);
915 assert(PhiIndex != -1 && "Incomplete phi during partial rename")(static_cast <bool> (PhiIndex != -1 && "Incomplete phi during partial rename"
) ? void (0) : __assert_fail ("PhiIndex != -1 && \"Incomplete phi during partial rename\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 915, __extension__ __PRETTY_FUNCTION__))
;
916 Phi->setIncomingValue(PhiIndex, IncomingVal);
917 } else
918 Phi->addIncoming(IncomingVal, BB);
919 }
920}
921
922/// \brief Rename a single basic block into MemorySSA form.
923/// Uses the standard SSA renaming algorithm.
924/// \returns The new incoming value.
925MemoryAccess *MemorySSA::renameBlock(BasicBlock *BB, MemoryAccess *IncomingVal,
926 bool RenameAllUses) {
927 auto It = PerBlockAccesses.find(BB);
928 // Skip most processing if the list is empty.
929 if (It != PerBlockAccesses.end()) {
930 AccessList *Accesses = It->second.get();
931 for (MemoryAccess &L : *Accesses) {
932 if (MemoryUseOrDef *MUD = dyn_cast<MemoryUseOrDef>(&L)) {
933 if (MUD->getDefiningAccess() == nullptr || RenameAllUses)
934 MUD->setDefiningAccess(IncomingVal);
935 if (isa<MemoryDef>(&L))
936 IncomingVal = &L;
937 } else {
938 IncomingVal = &L;
939 }
940 }
941 }
942 return IncomingVal;
943}
944
945/// \brief This is the standard SSA renaming algorithm.
946///
947/// We walk the dominator tree in preorder, renaming accesses, and then filling
948/// in phi nodes in our successors.
949void MemorySSA::renamePass(DomTreeNode *Root, MemoryAccess *IncomingVal,
950 SmallPtrSetImpl<BasicBlock *> &Visited,
951 bool SkipVisited, bool RenameAllUses) {
952 SmallVector<RenamePassData, 32> WorkStack;
953 // Skip everything if we already renamed this block and we are skipping.
954 // Note: You can't sink this into the if, because we need it to occur
955 // regardless of whether we skip blocks or not.
956 bool AlreadyVisited = !Visited.insert(Root->getBlock()).second;
957 if (SkipVisited && AlreadyVisited)
958 return;
959
960 IncomingVal = renameBlock(Root->getBlock(), IncomingVal, RenameAllUses);
961 renameSuccessorPhis(Root->getBlock(), IncomingVal, RenameAllUses);
962 WorkStack.push_back({Root, Root->begin(), IncomingVal});
963
964 while (!WorkStack.empty()) {
965 DomTreeNode *Node = WorkStack.back().DTN;
966 DomTreeNode::const_iterator ChildIt = WorkStack.back().ChildIt;
967 IncomingVal = WorkStack.back().IncomingVal;
968
969 if (ChildIt == Node->end()) {
970 WorkStack.pop_back();
971 } else {
972 DomTreeNode *Child = *ChildIt;
973 ++WorkStack.back().ChildIt;
974 BasicBlock *BB = Child->getBlock();
975 // Note: You can't sink this into the if, because we need it to occur
976 // regardless of whether we skip blocks or not.
977 AlreadyVisited = !Visited.insert(BB).second;
978 if (SkipVisited && AlreadyVisited) {
979 // We already visited this during our renaming, which can happen when
980 // being asked to rename multiple blocks. Figure out the incoming val,
981 // which is the last def.
982 // Incoming value can only change if there is a block def, and in that
983 // case, it's the last block def in the list.
984 if (auto *BlockDefs = getWritableBlockDefs(BB))
985 IncomingVal = &*BlockDefs->rbegin();
986 } else
987 IncomingVal = renameBlock(BB, IncomingVal, RenameAllUses);
988 renameSuccessorPhis(BB, IncomingVal, RenameAllUses);
989 WorkStack.push_back({Child, Child->begin(), IncomingVal});
990 }
991 }
992}
993
994/// \brief This handles unreachable block accesses by deleting phi nodes in
995/// unreachable blocks, and marking all other unreachable MemoryAccess's as
996/// being uses of the live on entry definition.
997void MemorySSA::markUnreachableAsLiveOnEntry(BasicBlock *BB) {
998 assert(!DT->isReachableFromEntry(BB) &&(static_cast <bool> (!DT->isReachableFromEntry(BB) &&
"Reachable block found while handling unreachable blocks") ?
void (0) : __assert_fail ("!DT->isReachableFromEntry(BB) && \"Reachable block found while handling unreachable blocks\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 999, __extension__ __PRETTY_FUNCTION__))
999 "Reachable block found while handling unreachable blocks")(static_cast <bool> (!DT->isReachableFromEntry(BB) &&
"Reachable block found while handling unreachable blocks") ?
void (0) : __assert_fail ("!DT->isReachableFromEntry(BB) && \"Reachable block found while handling unreachable blocks\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 999, __extension__ __PRETTY_FUNCTION__))
;
1000
1001 // Make sure phi nodes in our reachable successors end up with a
1002 // LiveOnEntryDef for our incoming edge, even though our block is forward
1003 // unreachable. We could just disconnect these blocks from the CFG fully,
1004 // but we do not right now.
1005 for (const BasicBlock *S : successors(BB)) {
1006 if (!DT->isReachableFromEntry(S))
1007 continue;
1008 auto It = PerBlockAccesses.find(S);
1009 // Rename the phi nodes in our successor block
1010 if (It == PerBlockAccesses.end() || !isa<MemoryPhi>(It->second->front()))
1011 continue;
1012 AccessList *Accesses = It->second.get();
1013 auto *Phi = cast<MemoryPhi>(&Accesses->front());
1014 Phi->addIncoming(LiveOnEntryDef.get(), BB);
1015 }
1016
1017 auto It = PerBlockAccesses.find(BB);
1018 if (It == PerBlockAccesses.end())
1019 return;
1020
1021 auto &Accesses = It->second;
1022 for (auto AI = Accesses->begin(), AE = Accesses->end(); AI != AE;) {
1023 auto Next = std::next(AI);
1024 // If we have a phi, just remove it. We are going to replace all
1025 // users with live on entry.
1026 if (auto *UseOrDef = dyn_cast<MemoryUseOrDef>(AI))
1027 UseOrDef->setDefiningAccess(LiveOnEntryDef.get());
1028 else
1029 Accesses->erase(AI);
1030 AI = Next;
1031 }
1032}
1033
1034MemorySSA::MemorySSA(Function &Func, AliasAnalysis *AA, DominatorTree *DT)
1035 : AA(AA), DT(DT), F(Func), LiveOnEntryDef(nullptr), Walker(nullptr),
1036 NextID(INVALID_MEMORYACCESS_ID) {
1037 buildMemorySSA();
1038}
1039
1040MemorySSA::~MemorySSA() {
1041 // Drop all our references
1042 for (const auto &Pair : PerBlockAccesses)
1043 for (MemoryAccess &MA : *Pair.second)
1044 MA.dropAllReferences();
1045}
1046
1047MemorySSA::AccessList *MemorySSA::getOrCreateAccessList(const BasicBlock *BB) {
1048 auto Res = PerBlockAccesses.insert(std::make_pair(BB, nullptr));
1049
1050 if (Res.second)
1051 Res.first->second = llvm::make_unique<AccessList>();
1052 return Res.first->second.get();
1053}
1054
1055MemorySSA::DefsList *MemorySSA::getOrCreateDefsList(const BasicBlock *BB) {
1056 auto Res = PerBlockDefs.insert(std::make_pair(BB, nullptr));
1057
1058 if (Res.second)
1059 Res.first->second = llvm::make_unique<DefsList>();
1060 return Res.first->second.get();
1061}
1062
1063namespace llvm {
1064
1065/// This class is a batch walker of all MemoryUse's in the program, and points
1066/// their defining access at the thing that actually clobbers them. Because it
1067/// is a batch walker that touches everything, it does not operate like the
1068/// other walkers. This walker is basically performing a top-down SSA renaming
1069/// pass, where the version stack is used as the cache. This enables it to be
1070/// significantly more time and memory efficient than using the regular walker,
1071/// which is walking bottom-up.
1072class MemorySSA::OptimizeUses {
1073public:
1074 OptimizeUses(MemorySSA *MSSA, MemorySSAWalker *Walker, AliasAnalysis *AA,
1075 DominatorTree *DT)
1076 : MSSA(MSSA), Walker(Walker), AA(AA), DT(DT) {
1077 Walker = MSSA->getWalker();
Value stored to 'Walker' is never read
1078 }
1079
1080 void optimizeUses();
1081
1082private:
1083 /// This represents where a given memorylocation is in the stack.
1084 struct MemlocStackInfo {
1085 // This essentially is keeping track of versions of the stack. Whenever
1086 // the stack changes due to pushes or pops, these versions increase.
1087 unsigned long StackEpoch;
1088 unsigned long PopEpoch;
1089 // This is the lower bound of places on the stack to check. It is equal to
1090 // the place the last stack walk ended.
1091 // Note: Correctness depends on this being initialized to 0, which densemap
1092 // does
1093 unsigned long LowerBound;
1094 const BasicBlock *LowerBoundBlock;
1095 // This is where the last walk for this memory location ended.
1096 unsigned long LastKill;
1097 bool LastKillValid;
1098 };
1099
1100 void optimizeUsesInBlock(const BasicBlock *, unsigned long &, unsigned long &,
1101 SmallVectorImpl<MemoryAccess *> &,
1102 DenseMap<MemoryLocOrCall, MemlocStackInfo> &);
1103
1104 MemorySSA *MSSA;
1105 MemorySSAWalker *Walker;
1106 AliasAnalysis *AA;
1107 DominatorTree *DT;
1108};
1109
1110} // end namespace llvm
1111
1112/// Optimize the uses in a given block This is basically the SSA renaming
1113/// algorithm, with one caveat: We are able to use a single stack for all
1114/// MemoryUses. This is because the set of *possible* reaching MemoryDefs is
1115/// the same for every MemoryUse. The *actual* clobbering MemoryDef is just
1116/// going to be some position in that stack of possible ones.
1117///
1118/// We track the stack positions that each MemoryLocation needs
1119/// to check, and last ended at. This is because we only want to check the
1120/// things that changed since last time. The same MemoryLocation should
1121/// get clobbered by the same store (getModRefInfo does not use invariantness or
1122/// things like this, and if they start, we can modify MemoryLocOrCall to
1123/// include relevant data)
1124void MemorySSA::OptimizeUses::optimizeUsesInBlock(
1125 const BasicBlock *BB, unsigned long &StackEpoch, unsigned long &PopEpoch,
1126 SmallVectorImpl<MemoryAccess *> &VersionStack,
1127 DenseMap<MemoryLocOrCall, MemlocStackInfo> &LocStackInfo) {
1128
1129 /// If no accesses, nothing to do.
1130 MemorySSA::AccessList *Accesses = MSSA->getWritableBlockAccesses(BB);
1131 if (Accesses == nullptr)
1132 return;
1133
1134 // Pop everything that doesn't dominate the current block off the stack,
1135 // increment the PopEpoch to account for this.
1136 while (true) {
1137 assert((static_cast <bool> (!VersionStack.empty() && "Version stack should have liveOnEntry sentinel dominating everything"
) ? void (0) : __assert_fail ("!VersionStack.empty() && \"Version stack should have liveOnEntry sentinel dominating everything\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1139, __extension__ __PRETTY_FUNCTION__))
1138 !VersionStack.empty() &&(static_cast <bool> (!VersionStack.empty() && "Version stack should have liveOnEntry sentinel dominating everything"
) ? void (0) : __assert_fail ("!VersionStack.empty() && \"Version stack should have liveOnEntry sentinel dominating everything\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1139, __extension__ __PRETTY_FUNCTION__))
1139 "Version stack should have liveOnEntry sentinel dominating everything")(static_cast <bool> (!VersionStack.empty() && "Version stack should have liveOnEntry sentinel dominating everything"
) ? void (0) : __assert_fail ("!VersionStack.empty() && \"Version stack should have liveOnEntry sentinel dominating everything\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1139, __extension__ __PRETTY_FUNCTION__))
;
1140 BasicBlock *BackBlock = VersionStack.back()->getBlock();
1141 if (DT->dominates(BackBlock, BB))
1142 break;
1143 while (VersionStack.back()->getBlock() == BackBlock)
1144 VersionStack.pop_back();
1145 ++PopEpoch;
1146 }
1147
1148 for (MemoryAccess &MA : *Accesses) {
1149 auto *MU = dyn_cast<MemoryUse>(&MA);
1150 if (!MU) {
1151 VersionStack.push_back(&MA);
1152 ++StackEpoch;
1153 continue;
1154 }
1155
1156 if (isUseTriviallyOptimizableToLiveOnEntry(*AA, MU->getMemoryInst())) {
1157 MU->setDefiningAccess(MSSA->getLiveOnEntryDef(), true);
1158 continue;
1159 }
1160
1161 MemoryLocOrCall UseMLOC(MU);
1162 auto &LocInfo = LocStackInfo[UseMLOC];
1163 // If the pop epoch changed, it means we've removed stuff from top of
1164 // stack due to changing blocks. We may have to reset the lower bound or
1165 // last kill info.
1166 if (LocInfo.PopEpoch != PopEpoch) {
1167 LocInfo.PopEpoch = PopEpoch;
1168 LocInfo.StackEpoch = StackEpoch;
1169 // If the lower bound was in something that no longer dominates us, we
1170 // have to reset it.
1171 // We can't simply track stack size, because the stack may have had
1172 // pushes/pops in the meantime.
1173 // XXX: This is non-optimal, but only is slower cases with heavily
1174 // branching dominator trees. To get the optimal number of queries would
1175 // be to make lowerbound and lastkill a per-loc stack, and pop it until
1176 // the top of that stack dominates us. This does not seem worth it ATM.
1177 // A much cheaper optimization would be to always explore the deepest
1178 // branch of the dominator tree first. This will guarantee this resets on
1179 // the smallest set of blocks.
1180 if (LocInfo.LowerBoundBlock && LocInfo.LowerBoundBlock != BB &&
1181 !DT->dominates(LocInfo.LowerBoundBlock, BB)) {
1182 // Reset the lower bound of things to check.
1183 // TODO: Some day we should be able to reset to last kill, rather than
1184 // 0.
1185 LocInfo.LowerBound = 0;
1186 LocInfo.LowerBoundBlock = VersionStack[0]->getBlock();
1187 LocInfo.LastKillValid = false;
1188 }
1189 } else if (LocInfo.StackEpoch != StackEpoch) {
1190 // If all that has changed is the StackEpoch, we only have to check the
1191 // new things on the stack, because we've checked everything before. In
1192 // this case, the lower bound of things to check remains the same.
1193 LocInfo.PopEpoch = PopEpoch;
1194 LocInfo.StackEpoch = StackEpoch;
1195 }
1196 if (!LocInfo.LastKillValid) {
1197 LocInfo.LastKill = VersionStack.size() - 1;
1198 LocInfo.LastKillValid = true;
1199 }
1200
1201 // At this point, we should have corrected last kill and LowerBound to be
1202 // in bounds.
1203 assert(LocInfo.LowerBound < VersionStack.size() &&(static_cast <bool> (LocInfo.LowerBound < VersionStack
.size() && "Lower bound out of range") ? void (0) : __assert_fail
("LocInfo.LowerBound < VersionStack.size() && \"Lower bound out of range\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1204, __extension__ __PRETTY_FUNCTION__))
1204 "Lower bound out of range")(static_cast <bool> (LocInfo.LowerBound < VersionStack
.size() && "Lower bound out of range") ? void (0) : __assert_fail
("LocInfo.LowerBound < VersionStack.size() && \"Lower bound out of range\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1204, __extension__ __PRETTY_FUNCTION__))
;
1205 assert(LocInfo.LastKill < VersionStack.size() &&(static_cast <bool> (LocInfo.LastKill < VersionStack
.size() && "Last kill info out of range") ? void (0) :
__assert_fail ("LocInfo.LastKill < VersionStack.size() && \"Last kill info out of range\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1206, __extension__ __PRETTY_FUNCTION__))
1206 "Last kill info out of range")(static_cast <bool> (LocInfo.LastKill < VersionStack
.size() && "Last kill info out of range") ? void (0) :
__assert_fail ("LocInfo.LastKill < VersionStack.size() && \"Last kill info out of range\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1206, __extension__ __PRETTY_FUNCTION__))
;
1207 // In any case, the new upper bound is the top of the stack.
1208 unsigned long UpperBound = VersionStack.size() - 1;
1209
1210 if (UpperBound - LocInfo.LowerBound > MaxCheckLimit) {
1211 DEBUG(dbgs() << "MemorySSA skipping optimization of " << *MU << " ("do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "MemorySSA skipping optimization of "
<< *MU << " (" << *(MU->getMemoryInst()
) << ")" << " because there are " << UpperBound
- LocInfo.LowerBound << " stores to disambiguate\n"; }
} while (false)
1212 << *(MU->getMemoryInst()) << ")"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "MemorySSA skipping optimization of "
<< *MU << " (" << *(MU->getMemoryInst()
) << ")" << " because there are " << UpperBound
- LocInfo.LowerBound << " stores to disambiguate\n"; }
} while (false)
1213 << " because there are " << UpperBound - LocInfo.LowerBounddo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "MemorySSA skipping optimization of "
<< *MU << " (" << *(MU->getMemoryInst()
) << ")" << " because there are " << UpperBound
- LocInfo.LowerBound << " stores to disambiguate\n"; }
} while (false)
1214 << " stores to disambiguate\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "MemorySSA skipping optimization of "
<< *MU << " (" << *(MU->getMemoryInst()
) << ")" << " because there are " << UpperBound
- LocInfo.LowerBound << " stores to disambiguate\n"; }
} while (false)
;
1215 // Because we did not walk, LastKill is no longer valid, as this may
1216 // have been a kill.
1217 LocInfo.LastKillValid = false;
1218 continue;
1219 }
1220 bool FoundClobberResult = false;
1221 while (UpperBound > LocInfo.LowerBound) {
1222 if (isa<MemoryPhi>(VersionStack[UpperBound])) {
1223 // For phis, use the walker, see where we ended up, go there
1224 Instruction *UseInst = MU->getMemoryInst();
1225 MemoryAccess *Result = Walker->getClobberingMemoryAccess(UseInst);
1226 // We are guaranteed to find it or something is wrong
1227 while (VersionStack[UpperBound] != Result) {
1228 assert(UpperBound != 0)(static_cast <bool> (UpperBound != 0) ? void (0) : __assert_fail
("UpperBound != 0", "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1228, __extension__ __PRETTY_FUNCTION__))
;
1229 --UpperBound;
1230 }
1231 FoundClobberResult = true;
1232 break;
1233 }
1234
1235 MemoryDef *MD = cast<MemoryDef>(VersionStack[UpperBound]);
1236 // If the lifetime of the pointer ends at this instruction, it's live on
1237 // entry.
1238 if (!UseMLOC.IsCall && lifetimeEndsAt(MD, UseMLOC.getLoc(), *AA)) {
1239 // Reset UpperBound to liveOnEntryDef's place in the stack
1240 UpperBound = 0;
1241 FoundClobberResult = true;
1242 break;
1243 }
1244 if (instructionClobbersQuery(MD, MU, UseMLOC, *AA)) {
1245 FoundClobberResult = true;
1246 break;
1247 }
1248 --UpperBound;
1249 }
1250 // At the end of this loop, UpperBound is either a clobber, or lower bound
1251 // PHI walking may cause it to be < LowerBound, and in fact, < LastKill.
1252 if (FoundClobberResult || UpperBound < LocInfo.LastKill) {
1253 MU->setDefiningAccess(VersionStack[UpperBound], true);
1254 // We were last killed now by where we got to
1255 LocInfo.LastKill = UpperBound;
1256 } else {
1257 // Otherwise, we checked all the new ones, and now we know we can get to
1258 // LastKill.
1259 MU->setDefiningAccess(VersionStack[LocInfo.LastKill], true);
1260 }
1261 LocInfo.LowerBound = VersionStack.size() - 1;
1262 LocInfo.LowerBoundBlock = BB;
1263 }
1264}
1265
1266/// Optimize uses to point to their actual clobbering definitions.
1267void MemorySSA::OptimizeUses::optimizeUses() {
1268 SmallVector<MemoryAccess *, 16> VersionStack;
1269 DenseMap<MemoryLocOrCall, MemlocStackInfo> LocStackInfo;
1270 VersionStack.push_back(MSSA->getLiveOnEntryDef());
1271
1272 unsigned long StackEpoch = 1;
1273 unsigned long PopEpoch = 1;
1274 // We perform a non-recursive top-down dominator tree walk.
1275 for (const auto *DomNode : depth_first(DT->getRootNode()))
1276 optimizeUsesInBlock(DomNode->getBlock(), StackEpoch, PopEpoch, VersionStack,
1277 LocStackInfo);
1278}
1279
1280void MemorySSA::placePHINodes(
1281 const SmallPtrSetImpl<BasicBlock *> &DefiningBlocks,
1282 const DenseMap<const BasicBlock *, unsigned int> &BBNumbers) {
1283 // Determine where our MemoryPhi's should go
1284 ForwardIDFCalculator IDFs(*DT);
1285 IDFs.setDefiningBlocks(DefiningBlocks);
1286 SmallVector<BasicBlock *, 32> IDFBlocks;
1287 IDFs.calculate(IDFBlocks);
1288
1289 std::sort(IDFBlocks.begin(), IDFBlocks.end(),
1290 [&BBNumbers](const BasicBlock *A, const BasicBlock *B) {
1291 return BBNumbers.lookup(A) < BBNumbers.lookup(B);
1292 });
1293
1294 // Now place MemoryPhi nodes.
1295 for (auto &BB : IDFBlocks)
1296 createMemoryPhi(BB);
1297}
1298
1299void MemorySSA::buildMemorySSA() {
1300 // We create an access to represent "live on entry", for things like
1301 // arguments or users of globals, where the memory they use is defined before
1302 // the beginning of the function. We do not actually insert it into the IR.
1303 // We do not define a live on exit for the immediate uses, and thus our
1304 // semantics do *not* imply that something with no immediate uses can simply
1305 // be removed.
1306 BasicBlock &StartingPoint = F.getEntryBlock();
1307 LiveOnEntryDef =
1308 llvm::make_unique<MemoryDef>(F.getContext(), nullptr, nullptr,
1309 &StartingPoint, NextID++);
1310 DenseMap<const BasicBlock *, unsigned int> BBNumbers;
1311 unsigned NextBBNum = 0;
1312
1313 // We maintain lists of memory accesses per-block, trading memory for time. We
1314 // could just look up the memory access for every possible instruction in the
1315 // stream.
1316 SmallPtrSet<BasicBlock *, 32> DefiningBlocks;
1317 // Go through each block, figure out where defs occur, and chain together all
1318 // the accesses.
1319 for (BasicBlock &B : F) {
1320 BBNumbers[&B] = NextBBNum++;
1321 bool InsertIntoDef = false;
1322 AccessList *Accesses = nullptr;
1323 DefsList *Defs = nullptr;
1324 for (Instruction &I : B) {
1325 MemoryUseOrDef *MUD = createNewAccess(&I);
1326 if (!MUD)
1327 continue;
1328
1329 if (!Accesses)
1330 Accesses = getOrCreateAccessList(&B);
1331 Accesses->push_back(MUD);
1332 if (isa<MemoryDef>(MUD)) {
1333 InsertIntoDef = true;
1334 if (!Defs)
1335 Defs = getOrCreateDefsList(&B);
1336 Defs->push_back(*MUD);
1337 }
1338 }
1339 if (InsertIntoDef)
1340 DefiningBlocks.insert(&B);
1341 }
1342 placePHINodes(DefiningBlocks, BBNumbers);
1343
1344 // Now do regular SSA renaming on the MemoryDef/MemoryUse. Visited will get
1345 // filled in with all blocks.
1346 SmallPtrSet<BasicBlock *, 16> Visited;
1347 renamePass(DT->getRootNode(), LiveOnEntryDef.get(), Visited);
1348
1349 CachingWalker *Walker = getWalkerImpl();
1350
1351 // We're doing a batch of updates; don't drop useful caches between them.
1352 Walker->setAutoResetWalker(false);
1353 OptimizeUses(this, Walker, AA, DT).optimizeUses();
1354 Walker->setAutoResetWalker(true);
1355 Walker->resetClobberWalker();
1356
1357 // Mark the uses in unreachable blocks as live on entry, so that they go
1358 // somewhere.
1359 for (auto &BB : F)
1360 if (!Visited.count(&BB))
1361 markUnreachableAsLiveOnEntry(&BB);
1362}
1363
1364MemorySSAWalker *MemorySSA::getWalker() { return getWalkerImpl(); }
1365
1366MemorySSA::CachingWalker *MemorySSA::getWalkerImpl() {
1367 if (Walker)
1368 return Walker.get();
1369
1370 Walker = llvm::make_unique<CachingWalker>(this, AA, DT);
1371 return Walker.get();
1372}
1373
1374// This is a helper function used by the creation routines. It places NewAccess
1375// into the access and defs lists for a given basic block, at the given
1376// insertion point.
1377void MemorySSA::insertIntoListsForBlock(MemoryAccess *NewAccess,
1378 const BasicBlock *BB,
1379 InsertionPlace Point) {
1380 auto *Accesses = getOrCreateAccessList(BB);
1381 if (Point == Beginning) {
1382 // If it's a phi node, it goes first, otherwise, it goes after any phi
1383 // nodes.
1384 if (isa<MemoryPhi>(NewAccess)) {
1385 Accesses->push_front(NewAccess);
1386 auto *Defs = getOrCreateDefsList(BB);
1387 Defs->push_front(*NewAccess);
1388 } else {
1389 auto AI = find_if_not(
1390 *Accesses, [](const MemoryAccess &MA) { return isa<MemoryPhi>(MA); });
1391 Accesses->insert(AI, NewAccess);
1392 if (!isa<MemoryUse>(NewAccess)) {
1393 auto *Defs = getOrCreateDefsList(BB);
1394 auto DI = find_if_not(
1395 *Defs, [](const MemoryAccess &MA) { return isa<MemoryPhi>(MA); });
1396 Defs->insert(DI, *NewAccess);
1397 }
1398 }
1399 } else {
1400 Accesses->push_back(NewAccess);
1401 if (!isa<MemoryUse>(NewAccess)) {
1402 auto *Defs = getOrCreateDefsList(BB);
1403 Defs->push_back(*NewAccess);
1404 }
1405 }
1406 BlockNumberingValid.erase(BB);
1407}
1408
1409void MemorySSA::insertIntoListsBefore(MemoryAccess *What, const BasicBlock *BB,
1410 AccessList::iterator InsertPt) {
1411 auto *Accesses = getWritableBlockAccesses(BB);
1412 bool WasEnd = InsertPt == Accesses->end();
1413 Accesses->insert(AccessList::iterator(InsertPt), What);
1414 if (!isa<MemoryUse>(What)) {
1415 auto *Defs = getOrCreateDefsList(BB);
1416 // If we got asked to insert at the end, we have an easy job, just shove it
1417 // at the end. If we got asked to insert before an existing def, we also get
1418 // an terator. If we got asked to insert before a use, we have to hunt for
1419 // the next def.
1420 if (WasEnd) {
1421 Defs->push_back(*What);
1422 } else if (isa<MemoryDef>(InsertPt)) {
1423 Defs->insert(InsertPt->getDefsIterator(), *What);
1424 } else {
1425 while (InsertPt != Accesses->end() && !isa<MemoryDef>(InsertPt))
1426 ++InsertPt;
1427 // Either we found a def, or we are inserting at the end
1428 if (InsertPt == Accesses->end())
1429 Defs->push_back(*What);
1430 else
1431 Defs->insert(InsertPt->getDefsIterator(), *What);
1432 }
1433 }
1434 BlockNumberingValid.erase(BB);
1435}
1436
1437// Move What before Where in the IR. The end result is taht What will belong to
1438// the right lists and have the right Block set, but will not otherwise be
1439// correct. It will not have the right defining access, and if it is a def,
1440// things below it will not properly be updated.
1441void MemorySSA::moveTo(MemoryUseOrDef *What, BasicBlock *BB,
1442 AccessList::iterator Where) {
1443 // Keep it in the lookup tables, remove from the lists
1444 removeFromLists(What, false);
1445 What->setBlock(BB);
1446 insertIntoListsBefore(What, BB, Where);
1447}
1448
1449void MemorySSA::moveTo(MemoryUseOrDef *What, BasicBlock *BB,
1450 InsertionPlace Point) {
1451 removeFromLists(What, false);
1452 What->setBlock(BB);
1453 insertIntoListsForBlock(What, BB, Point);
1454}
1455
1456MemoryPhi *MemorySSA::createMemoryPhi(BasicBlock *BB) {
1457 assert(!getMemoryAccess(BB) && "MemoryPhi already exists for this BB")(static_cast <bool> (!getMemoryAccess(BB) && "MemoryPhi already exists for this BB"
) ? void (0) : __assert_fail ("!getMemoryAccess(BB) && \"MemoryPhi already exists for this BB\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1457, __extension__ __PRETTY_FUNCTION__))
;
1458 MemoryPhi *Phi = new MemoryPhi(BB->getContext(), BB, NextID++);
1459 // Phi's always are placed at the front of the block.
1460 insertIntoListsForBlock(Phi, BB, Beginning);
1461 ValueToMemoryAccess[BB] = Phi;
1462 return Phi;
1463}
1464
1465MemoryUseOrDef *MemorySSA::createDefinedAccess(Instruction *I,
1466 MemoryAccess *Definition) {
1467 assert(!isa<PHINode>(I) && "Cannot create a defined access for a PHI")(static_cast <bool> (!isa<PHINode>(I) && "Cannot create a defined access for a PHI"
) ? void (0) : __assert_fail ("!isa<PHINode>(I) && \"Cannot create a defined access for a PHI\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1467, __extension__ __PRETTY_FUNCTION__))
;
1468 MemoryUseOrDef *NewAccess = createNewAccess(I);
1469 assert((static_cast <bool> (NewAccess != nullptr && "Tried to create a memory access for a non-memory touching instruction"
) ? void (0) : __assert_fail ("NewAccess != nullptr && \"Tried to create a memory access for a non-memory touching instruction\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1471, __extension__ __PRETTY_FUNCTION__))
1470 NewAccess != nullptr &&(static_cast <bool> (NewAccess != nullptr && "Tried to create a memory access for a non-memory touching instruction"
) ? void (0) : __assert_fail ("NewAccess != nullptr && \"Tried to create a memory access for a non-memory touching instruction\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1471, __extension__ __PRETTY_FUNCTION__))
1471 "Tried to create a memory access for a non-memory touching instruction")(static_cast <bool> (NewAccess != nullptr && "Tried to create a memory access for a non-memory touching instruction"
) ? void (0) : __assert_fail ("NewAccess != nullptr && \"Tried to create a memory access for a non-memory touching instruction\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1471, __extension__ __PRETTY_FUNCTION__))
;
1472 NewAccess->setDefiningAccess(Definition);
1473 return NewAccess;
1474}
1475
1476// Return true if the instruction has ordering constraints.
1477// Note specifically that this only considers stores and loads
1478// because others are still considered ModRef by getModRefInfo.
1479static inline bool isOrdered(const Instruction *I) {
1480 if (auto *SI = dyn_cast<StoreInst>(I)) {
1481 if (!SI->isUnordered())
1482 return true;
1483 } else if (auto *LI = dyn_cast<LoadInst>(I)) {
1484 if (!LI->isUnordered())
1485 return true;
1486 }
1487 return false;
1488}
1489
1490/// \brief Helper function to create new memory accesses
1491MemoryUseOrDef *MemorySSA::createNewAccess(Instruction *I) {
1492 // The assume intrinsic has a control dependency which we model by claiming
1493 // that it writes arbitrarily. Ignore that fake memory dependency here.
1494 // FIXME: Replace this special casing with a more accurate modelling of
1495 // assume's control dependency.
1496 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I))
1497 if (II->getIntrinsicID() == Intrinsic::assume)
1498 return nullptr;
1499
1500 // Find out what affect this instruction has on memory.
1501 ModRefInfo ModRef = AA->getModRefInfo(I, None);
1502 // The isOrdered check is used to ensure that volatiles end up as defs
1503 // (atomics end up as ModRef right now anyway). Until we separate the
1504 // ordering chain from the memory chain, this enables people to see at least
1505 // some relative ordering to volatiles. Note that getClobberingMemoryAccess
1506 // will still give an answer that bypasses other volatile loads. TODO:
1507 // Separate memory aliasing and ordering into two different chains so that we
1508 // can precisely represent both "what memory will this read/write/is clobbered
1509 // by" and "what instructions can I move this past".
1510 bool Def = isModSet(ModRef) || isOrdered(I);
1511 bool Use = isRefSet(ModRef);
1512
1513 // It's possible for an instruction to not modify memory at all. During
1514 // construction, we ignore them.
1515 if (!Def && !Use)
1516 return nullptr;
1517
1518 assert((Def || Use) &&(static_cast <bool> ((Def || Use) && "Trying to create a memory access with a non-memory instruction"
) ? void (0) : __assert_fail ("(Def || Use) && \"Trying to create a memory access with a non-memory instruction\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1519, __extension__ __PRETTY_FUNCTION__))
1519 "Trying to create a memory access with a non-memory instruction")(static_cast <bool> ((Def || Use) && "Trying to create a memory access with a non-memory instruction"
) ? void (0) : __assert_fail ("(Def || Use) && \"Trying to create a memory access with a non-memory instruction\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1519, __extension__ __PRETTY_FUNCTION__))
;
1520
1521 MemoryUseOrDef *MUD;
1522 if (Def)
1523 MUD = new MemoryDef(I->getContext(), nullptr, I, I->getParent(), NextID++);
1524 else
1525 MUD = new MemoryUse(I->getContext(), nullptr, I, I->getParent());
1526 ValueToMemoryAccess[I] = MUD;
1527 return MUD;
1528}
1529
1530/// \brief Returns true if \p Replacer dominates \p Replacee .
1531bool MemorySSA::dominatesUse(const MemoryAccess *Replacer,
1532 const MemoryAccess *Replacee) const {
1533 if (isa<MemoryUseOrDef>(Replacee))
1534 return DT->dominates(Replacer->getBlock(), Replacee->getBlock());
1535 const auto *MP = cast<MemoryPhi>(Replacee);
1536 // For a phi node, the use occurs in the predecessor block of the phi node.
1537 // Since we may occur multiple times in the phi node, we have to check each
1538 // operand to ensure Replacer dominates each operand where Replacee occurs.
1539 for (const Use &Arg : MP->operands()) {
1540 if (Arg.get() != Replacee &&
1541 !DT->dominates(Replacer->getBlock(), MP->getIncomingBlock(Arg)))
1542 return false;
1543 }
1544 return true;
1545}
1546
1547/// \brief Properly remove \p MA from all of MemorySSA's lookup tables.
1548void MemorySSA::removeFromLookups(MemoryAccess *MA) {
1549 assert(MA->use_empty() &&(static_cast <bool> (MA->use_empty() && "Trying to remove memory access that still has uses"
) ? void (0) : __assert_fail ("MA->use_empty() && \"Trying to remove memory access that still has uses\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1550, __extension__ __PRETTY_FUNCTION__))
1550 "Trying to remove memory access that still has uses")(static_cast <bool> (MA->use_empty() && "Trying to remove memory access that still has uses"
) ? void (0) : __assert_fail ("MA->use_empty() && \"Trying to remove memory access that still has uses\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1550, __extension__ __PRETTY_FUNCTION__))
;
1551 BlockNumbering.erase(MA);
1552 if (MemoryUseOrDef *MUD = dyn_cast<MemoryUseOrDef>(MA))
1553 MUD->setDefiningAccess(nullptr);
1554 // Invalidate our walker's cache if necessary
1555 if (!isa<MemoryUse>(MA))
1556 Walker->invalidateInfo(MA);
1557 // The call below to erase will destroy MA, so we can't change the order we
1558 // are doing things here
1559 Value *MemoryInst;
1560 if (MemoryUseOrDef *MUD = dyn_cast<MemoryUseOrDef>(MA)) {
1561 MemoryInst = MUD->getMemoryInst();
1562 } else {
1563 MemoryInst = MA->getBlock();
1564 }
1565 auto VMA = ValueToMemoryAccess.find(MemoryInst);
1566 if (VMA->second == MA)
1567 ValueToMemoryAccess.erase(VMA);
1568}
1569
1570/// \brief Properly remove \p MA from all of MemorySSA's lists.
1571///
1572/// Because of the way the intrusive list and use lists work, it is important to
1573/// do removal in the right order.
1574/// ShouldDelete defaults to true, and will cause the memory access to also be
1575/// deleted, not just removed.
1576void MemorySSA::removeFromLists(MemoryAccess *MA, bool ShouldDelete) {
1577 // The access list owns the reference, so we erase it from the non-owning list
1578 // first.
1579 if (!isa<MemoryUse>(MA)) {
1580 auto DefsIt = PerBlockDefs.find(MA->getBlock());
1581 std::unique_ptr<DefsList> &Defs = DefsIt->second;
1582 Defs->remove(*MA);
1583 if (Defs->empty())
1584 PerBlockDefs.erase(DefsIt);
1585 }
1586
1587 // The erase call here will delete it. If we don't want it deleted, we call
1588 // remove instead.
1589 auto AccessIt = PerBlockAccesses.find(MA->getBlock());
1590 std::unique_ptr<AccessList> &Accesses = AccessIt->second;
1591 if (ShouldDelete)
1592 Accesses->erase(MA);
1593 else
1594 Accesses->remove(MA);
1595
1596 if (Accesses->empty())
1597 PerBlockAccesses.erase(AccessIt);
1598}
1599
1600void MemorySSA::print(raw_ostream &OS) const {
1601 MemorySSAAnnotatedWriter Writer(this);
1602 F.print(OS, &Writer);
1603}
1604
1605#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1606LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void MemorySSA::dump() const { print(dbgs()); }
1607#endif
1608
1609void MemorySSA::verifyMemorySSA() const {
1610 verifyDefUses(F);
1611 verifyDomination(F);
1612 verifyOrdering(F);
1613 Walker->verify(this);
1614}
1615
1616/// \brief Verify that the order and existence of MemoryAccesses matches the
1617/// order and existence of memory affecting instructions.
1618void MemorySSA::verifyOrdering(Function &F) const {
1619 // Walk all the blocks, comparing what the lookups think and what the access
1620 // lists think, as well as the order in the blocks vs the order in the access
1621 // lists.
1622 SmallVector<MemoryAccess *, 32> ActualAccesses;
1623 SmallVector<MemoryAccess *, 32> ActualDefs;
1624 for (BasicBlock &B : F) {
1625 const AccessList *AL = getBlockAccesses(&B);
1626 const auto *DL = getBlockDefs(&B);
1627 MemoryAccess *Phi = getMemoryAccess(&B);
1628 if (Phi) {
1629 ActualAccesses.push_back(Phi);
1630 ActualDefs.push_back(Phi);
1631 }
1632
1633 for (Instruction &I : B) {
1634 MemoryAccess *MA = getMemoryAccess(&I);
1635 assert((!MA || (AL && (isa<MemoryUse>(MA) || DL))) &&(static_cast <bool> ((!MA || (AL && (isa<MemoryUse
>(MA) || DL))) && "We have memory affecting instructions "
"in this block but they are not in the " "access list or defs list"
) ? void (0) : __assert_fail ("(!MA || (AL && (isa<MemoryUse>(MA) || DL))) && \"We have memory affecting instructions \" \"in this block but they are not in the \" \"access list or defs list\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1638, __extension__ __PRETTY_FUNCTION__))
1636 "We have memory affecting instructions "(static_cast <bool> ((!MA || (AL && (isa<MemoryUse
>(MA) || DL))) && "We have memory affecting instructions "
"in this block but they are not in the " "access list or defs list"
) ? void (0) : __assert_fail ("(!MA || (AL && (isa<MemoryUse>(MA) || DL))) && \"We have memory affecting instructions \" \"in this block but they are not in the \" \"access list or defs list\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1638, __extension__ __PRETTY_FUNCTION__))
1637 "in this block but they are not in the "(static_cast <bool> ((!MA || (AL && (isa<MemoryUse
>(MA) || DL))) && "We have memory affecting instructions "
"in this block but they are not in the " "access list or defs list"
) ? void (0) : __assert_fail ("(!MA || (AL && (isa<MemoryUse>(MA) || DL))) && \"We have memory affecting instructions \" \"in this block but they are not in the \" \"access list or defs list\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1638, __extension__ __PRETTY_FUNCTION__))
1638 "access list or defs list")(static_cast <bool> ((!MA || (AL && (isa<MemoryUse
>(MA) || DL))) && "We have memory affecting instructions "
"in this block but they are not in the " "access list or defs list"
) ? void (0) : __assert_fail ("(!MA || (AL && (isa<MemoryUse>(MA) || DL))) && \"We have memory affecting instructions \" \"in this block but they are not in the \" \"access list or defs list\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1638, __extension__ __PRETTY_FUNCTION__))
;
1639 if (MA) {
1640 ActualAccesses.push_back(MA);
1641 if (isa<MemoryDef>(MA))
1642 ActualDefs.push_back(MA);
1643 }
1644 }
1645 // Either we hit the assert, really have no accesses, or we have both
1646 // accesses and an access list.
1647 // Same with defs.
1648 if (!AL && !DL)
1649 continue;
1650 assert(AL->size() == ActualAccesses.size() &&(static_cast <bool> (AL->size() == ActualAccesses.size
() && "We don't have the same number of accesses in the block as on the "
"access list") ? void (0) : __assert_fail ("AL->size() == ActualAccesses.size() && \"We don't have the same number of accesses in the block as on the \" \"access list\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1652, __extension__ __PRETTY_FUNCTION__))
1651 "We don't have the same number of accesses in the block as on the "(static_cast <bool> (AL->size() == ActualAccesses.size
() && "We don't have the same number of accesses in the block as on the "
"access list") ? void (0) : __assert_fail ("AL->size() == ActualAccesses.size() && \"We don't have the same number of accesses in the block as on the \" \"access list\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1652, __extension__ __PRETTY_FUNCTION__))
1652 "access list")(static_cast <bool> (AL->size() == ActualAccesses.size
() && "We don't have the same number of accesses in the block as on the "
"access list") ? void (0) : __assert_fail ("AL->size() == ActualAccesses.size() && \"We don't have the same number of accesses in the block as on the \" \"access list\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1652, __extension__ __PRETTY_FUNCTION__))
;
1653 assert((DL || ActualDefs.size() == 0) &&(static_cast <bool> ((DL || ActualDefs.size() == 0) &&
"Either we should have a defs list, or we should have no defs"
) ? void (0) : __assert_fail ("(DL || ActualDefs.size() == 0) && \"Either we should have a defs list, or we should have no defs\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1654, __extension__ __PRETTY_FUNCTION__))
1654 "Either we should have a defs list, or we should have no defs")(static_cast <bool> ((DL || ActualDefs.size() == 0) &&
"Either we should have a defs list, or we should have no defs"
) ? void (0) : __assert_fail ("(DL || ActualDefs.size() == 0) && \"Either we should have a defs list, or we should have no defs\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1654, __extension__ __PRETTY_FUNCTION__))
;
1655 assert((!DL || DL->size() == ActualDefs.size()) &&(static_cast <bool> ((!DL || DL->size() == ActualDefs
.size()) && "We don't have the same number of defs in the block as on the "
"def list") ? void (0) : __assert_fail ("(!DL || DL->size() == ActualDefs.size()) && \"We don't have the same number of defs in the block as on the \" \"def list\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1657, __extension__ __PRETTY_FUNCTION__))
1656 "We don't have the same number of defs in the block as on the "(static_cast <bool> ((!DL || DL->size() == ActualDefs
.size()) && "We don't have the same number of defs in the block as on the "
"def list") ? void (0) : __assert_fail ("(!DL || DL->size() == ActualDefs.size()) && \"We don't have the same number of defs in the block as on the \" \"def list\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1657, __extension__ __PRETTY_FUNCTION__))
1657 "def list")(static_cast <bool> ((!DL || DL->size() == ActualDefs
.size()) && "We don't have the same number of defs in the block as on the "
"def list") ? void (0) : __assert_fail ("(!DL || DL->size() == ActualDefs.size()) && \"We don't have the same number of defs in the block as on the \" \"def list\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1657, __extension__ __PRETTY_FUNCTION__))
;
1658 auto ALI = AL->begin();
1659 auto AAI = ActualAccesses.begin();
1660 while (ALI != AL->end() && AAI != ActualAccesses.end()) {
1661 assert(&*ALI == *AAI && "Not the same accesses in the same order")(static_cast <bool> (&*ALI == *AAI && "Not the same accesses in the same order"
) ? void (0) : __assert_fail ("&*ALI == *AAI && \"Not the same accesses in the same order\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1661, __extension__ __PRETTY_FUNCTION__))
;
1662 ++ALI;
1663 ++AAI;
1664 }
1665 ActualAccesses.clear();
1666 if (DL) {
1667 auto DLI = DL->begin();
1668 auto ADI = ActualDefs.begin();
1669 while (DLI != DL->end() && ADI != ActualDefs.end()) {
1670 assert(&*DLI == *ADI && "Not the same defs in the same order")(static_cast <bool> (&*DLI == *ADI && "Not the same defs in the same order"
) ? void (0) : __assert_fail ("&*DLI == *ADI && \"Not the same defs in the same order\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1670, __extension__ __PRETTY_FUNCTION__))
;
1671 ++DLI;
1672 ++ADI;
1673 }
1674 }
1675 ActualDefs.clear();
1676 }
1677}
1678
1679/// \brief Verify the domination properties of MemorySSA by checking that each
1680/// definition dominates all of its uses.
1681void MemorySSA::verifyDomination(Function &F) const {
1682#ifndef NDEBUG
1683 for (BasicBlock &B : F) {
1684 // Phi nodes are attached to basic blocks
1685 if (MemoryPhi *MP = getMemoryAccess(&B))
1686 for (const Use &U : MP->uses())
1687 assert(dominates(MP, U) && "Memory PHI does not dominate it's uses")(static_cast <bool> (dominates(MP, U) && "Memory PHI does not dominate it's uses"
) ? void (0) : __assert_fail ("dominates(MP, U) && \"Memory PHI does not dominate it's uses\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1687, __extension__ __PRETTY_FUNCTION__))
;
1688
1689 for (Instruction &I : B) {
1690 MemoryAccess *MD = dyn_cast_or_null<MemoryDef>(getMemoryAccess(&I));
1691 if (!MD)
1692 continue;
1693
1694 for (const Use &U : MD->uses())
1695 assert(dominates(MD, U) && "Memory Def does not dominate it's uses")(static_cast <bool> (dominates(MD, U) && "Memory Def does not dominate it's uses"
) ? void (0) : __assert_fail ("dominates(MD, U) && \"Memory Def does not dominate it's uses\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1695, __extension__ __PRETTY_FUNCTION__))
;
1696 }
1697 }
1698#endif
1699}
1700
1701/// \brief Verify the def-use lists in MemorySSA, by verifying that \p Use
1702/// appears in the use list of \p Def.
1703void MemorySSA::verifyUseInDefs(MemoryAccess *Def, MemoryAccess *Use) const {
1704#ifndef NDEBUG
1705 // The live on entry use may cause us to get a NULL def here
1706 if (!Def)
1707 assert(isLiveOnEntryDef(Use) &&(static_cast <bool> (isLiveOnEntryDef(Use) && "Null def but use not point to live on entry def"
) ? void (0) : __assert_fail ("isLiveOnEntryDef(Use) && \"Null def but use not point to live on entry def\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1708, __extension__ __PRETTY_FUNCTION__))
1708 "Null def but use not point to live on entry def")(static_cast <bool> (isLiveOnEntryDef(Use) && "Null def but use not point to live on entry def"
) ? void (0) : __assert_fail ("isLiveOnEntryDef(Use) && \"Null def but use not point to live on entry def\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1708, __extension__ __PRETTY_FUNCTION__))
;
1709 else
1710 assert(is_contained(Def->users(), Use) &&(static_cast <bool> (is_contained(Def->users(), Use)
&& "Did not find use in def's use list") ? void (0) :
__assert_fail ("is_contained(Def->users(), Use) && \"Did not find use in def's use list\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1711, __extension__ __PRETTY_FUNCTION__))
1711 "Did not find use in def's use list")(static_cast <bool> (is_contained(Def->users(), Use)
&& "Did not find use in def's use list") ? void (0) :
__assert_fail ("is_contained(Def->users(), Use) && \"Did not find use in def's use list\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1711, __extension__ __PRETTY_FUNCTION__))
;
1712#endif
1713}
1714
1715/// \brief Verify the immediate use information, by walking all the memory
1716/// accesses and verifying that, for each use, it appears in the
1717/// appropriate def's use list
1718void MemorySSA::verifyDefUses(Function &F) const {
1719 for (BasicBlock &B : F) {
1720 // Phi nodes are attached to basic blocks
1721 if (MemoryPhi *Phi = getMemoryAccess(&B)) {
1722 assert(Phi->getNumOperands() == static_cast<unsigned>(std::distance((static_cast <bool> (Phi->getNumOperands() == static_cast
<unsigned>(std::distance( pred_begin(&B), pred_end(
&B))) && "Incomplete MemoryPhi Node") ? void (0) :
__assert_fail ("Phi->getNumOperands() == static_cast<unsigned>(std::distance( pred_begin(&B), pred_end(&B))) && \"Incomplete MemoryPhi Node\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1724, __extension__ __PRETTY_FUNCTION__))
1723 pred_begin(&B), pred_end(&B))) &&(static_cast <bool> (Phi->getNumOperands() == static_cast
<unsigned>(std::distance( pred_begin(&B), pred_end(
&B))) && "Incomplete MemoryPhi Node") ? void (0) :
__assert_fail ("Phi->getNumOperands() == static_cast<unsigned>(std::distance( pred_begin(&B), pred_end(&B))) && \"Incomplete MemoryPhi Node\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1724, __extension__ __PRETTY_FUNCTION__))
1724 "Incomplete MemoryPhi Node")(static_cast <bool> (Phi->getNumOperands() == static_cast
<unsigned>(std::distance( pred_begin(&B), pred_end(
&B))) && "Incomplete MemoryPhi Node") ? void (0) :
__assert_fail ("Phi->getNumOperands() == static_cast<unsigned>(std::distance( pred_begin(&B), pred_end(&B))) && \"Incomplete MemoryPhi Node\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1724, __extension__ __PRETTY_FUNCTION__))
;
1725 for (unsigned I = 0, E = Phi->getNumIncomingValues(); I != E; ++I)
1726 verifyUseInDefs(Phi->getIncomingValue(I), Phi);
1727 }
1728
1729 for (Instruction &I : B) {
1730 if (MemoryUseOrDef *MA = getMemoryAccess(&I)) {
1731 verifyUseInDefs(MA->getDefiningAccess(), MA);
1732 }
1733 }
1734 }
1735}
1736
1737MemoryUseOrDef *MemorySSA::getMemoryAccess(const Instruction *I) const {
1738 return cast_or_null<MemoryUseOrDef>(ValueToMemoryAccess.lookup(I));
1739}
1740
1741MemoryPhi *MemorySSA::getMemoryAccess(const BasicBlock *BB) const {
1742 return cast_or_null<MemoryPhi>(ValueToMemoryAccess.lookup(cast<Value>(BB)));
1743}
1744
1745/// Perform a local numbering on blocks so that instruction ordering can be
1746/// determined in constant time.
1747/// TODO: We currently just number in order. If we numbered by N, we could
1748/// allow at least N-1 sequences of insertBefore or insertAfter (and at least
1749/// log2(N) sequences of mixed before and after) without needing to invalidate
1750/// the numbering.
1751void MemorySSA::renumberBlock(const BasicBlock *B) const {
1752 // The pre-increment ensures the numbers really start at 1.
1753 unsigned long CurrentNumber = 0;
1754 const AccessList *AL = getBlockAccesses(B);
1755 assert(AL != nullptr && "Asking to renumber an empty block")(static_cast <bool> (AL != nullptr && "Asking to renumber an empty block"
) ? void (0) : __assert_fail ("AL != nullptr && \"Asking to renumber an empty block\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1755, __extension__ __PRETTY_FUNCTION__))
;
1756 for (const auto &I : *AL)
1757 BlockNumbering[&I] = ++CurrentNumber;
1758 BlockNumberingValid.insert(B);
1759}
1760
1761/// \brief Determine, for two memory accesses in the same block,
1762/// whether \p Dominator dominates \p Dominatee.
1763/// \returns True if \p Dominator dominates \p Dominatee.
1764bool MemorySSA::locallyDominates(const MemoryAccess *Dominator,
1765 const MemoryAccess *Dominatee) const {
1766 const BasicBlock *DominatorBlock = Dominator->getBlock();
1767
1768 assert((DominatorBlock == Dominatee->getBlock()) &&(static_cast <bool> ((DominatorBlock == Dominatee->getBlock
()) && "Asking for local domination when accesses are in different blocks!"
) ? void (0) : __assert_fail ("(DominatorBlock == Dominatee->getBlock()) && \"Asking for local domination when accesses are in different blocks!\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1769, __extension__ __PRETTY_FUNCTION__))
1769 "Asking for local domination when accesses are in different blocks!")(static_cast <bool> ((DominatorBlock == Dominatee->getBlock
()) && "Asking for local domination when accesses are in different blocks!"
) ? void (0) : __assert_fail ("(DominatorBlock == Dominatee->getBlock()) && \"Asking for local domination when accesses are in different blocks!\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1769, __extension__ __PRETTY_FUNCTION__))
;
1770 // A node dominates itself.
1771 if (Dominatee == Dominator)
1772 return true;
1773
1774 // When Dominatee is defined on function entry, it is not dominated by another
1775 // memory access.
1776 if (isLiveOnEntryDef(Dominatee))
1777 return false;
1778
1779 // When Dominator is defined on function entry, it dominates the other memory
1780 // access.
1781 if (isLiveOnEntryDef(Dominator))
1782 return true;
1783
1784 if (!BlockNumberingValid.count(DominatorBlock))
1785 renumberBlock(DominatorBlock);
1786
1787 unsigned long DominatorNum = BlockNumbering.lookup(Dominator);
1788 // All numbers start with 1
1789 assert(DominatorNum != 0 && "Block was not numbered properly")(static_cast <bool> (DominatorNum != 0 && "Block was not numbered properly"
) ? void (0) : __assert_fail ("DominatorNum != 0 && \"Block was not numbered properly\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1789, __extension__ __PRETTY_FUNCTION__))
;
1790 unsigned long DominateeNum = BlockNumbering.lookup(Dominatee);
1791 assert(DominateeNum != 0 && "Block was not numbered properly")(static_cast <bool> (DominateeNum != 0 && "Block was not numbered properly"
) ? void (0) : __assert_fail ("DominateeNum != 0 && \"Block was not numbered properly\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1791, __extension__ __PRETTY_FUNCTION__))
;
1792 return DominatorNum < DominateeNum;
1793}
1794
1795bool MemorySSA::dominates(const MemoryAccess *Dominator,
1796 const MemoryAccess *Dominatee) const {
1797 if (Dominator == Dominatee)
1798 return true;
1799
1800 if (isLiveOnEntryDef(Dominatee))
1801 return false;
1802
1803 if (Dominator->getBlock() != Dominatee->getBlock())
1804 return DT->dominates(Dominator->getBlock(), Dominatee->getBlock());
1805 return locallyDominates(Dominator, Dominatee);
1806}
1807
1808bool MemorySSA::dominates(const MemoryAccess *Dominator,
1809 const Use &Dominatee) const {
1810 if (MemoryPhi *MP = dyn_cast<MemoryPhi>(Dominatee.getUser())) {
1811 BasicBlock *UseBB = MP->getIncomingBlock(Dominatee);
1812 // The def must dominate the incoming block of the phi.
1813 if (UseBB != Dominator->getBlock())
1814 return DT->dominates(Dominator->getBlock(), UseBB);
1815 // If the UseBB and the DefBB are the same, compare locally.
1816 return locallyDominates(Dominator, cast<MemoryAccess>(Dominatee));
1817 }
1818 // If it's not a PHI node use, the normal dominates can already handle it.
1819 return dominates(Dominator, cast<MemoryAccess>(Dominatee.getUser()));
1820}
1821
1822const static char LiveOnEntryStr[] = "liveOnEntry";
1823
1824void MemoryAccess::print(raw_ostream &OS) const {
1825 switch (getValueID()) {
1826 case MemoryPhiVal: return static_cast<const MemoryPhi *>(this)->print(OS);
1827 case MemoryDefVal: return static_cast<const MemoryDef *>(this)->print(OS);
1828 case MemoryUseVal: return static_cast<const MemoryUse *>(this)->print(OS);
1829 }
1830 llvm_unreachable("invalid value id")::llvm::llvm_unreachable_internal("invalid value id", "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1830)
;
1831}
1832
1833void MemoryDef::print(raw_ostream &OS) const {
1834 MemoryAccess *UO = getDefiningAccess();
1835
1836 OS << getID() << " = MemoryDef(";
1837 if (UO && UO->getID())
1838 OS << UO->getID();
1839 else
1840 OS << LiveOnEntryStr;
1841 OS << ')';
1842}
1843
1844void MemoryPhi::print(raw_ostream &OS) const {
1845 bool First = true;
1846 OS << getID() << " = MemoryPhi(";
1847 for (const auto &Op : operands()) {
1848 BasicBlock *BB = getIncomingBlock(Op);
1849 MemoryAccess *MA = cast<MemoryAccess>(Op);
1850 if (!First)
1851 OS << ',';
1852 else
1853 First = false;
1854
1855 OS << '{';
1856 if (BB->hasName())
1857 OS << BB->getName();
1858 else
1859 BB->printAsOperand(OS, false);
1860 OS << ',';
1861 if (unsigned ID = MA->getID())
1862 OS << ID;
1863 else
1864 OS << LiveOnEntryStr;
1865 OS << '}';
1866 }
1867 OS << ')';
1868}
1869
1870void MemoryUse::print(raw_ostream &OS) const {
1871 MemoryAccess *UO = getDefiningAccess();
1872 OS << "MemoryUse(";
1873 if (UO && UO->getID())
1874 OS << UO->getID();
1875 else
1876 OS << LiveOnEntryStr;
1877 OS << ')';
1878}
1879
1880void MemoryAccess::dump() const {
1881// Cannot completely remove virtual function even in release mode.
1882#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1883 print(dbgs());
1884 dbgs() << "\n";
1885#endif
1886}
1887
1888char MemorySSAPrinterLegacyPass::ID = 0;
1889
1890MemorySSAPrinterLegacyPass::MemorySSAPrinterLegacyPass() : FunctionPass(ID) {
1891 initializeMemorySSAPrinterLegacyPassPass(*PassRegistry::getPassRegistry());
1892}
1893
1894void MemorySSAPrinterLegacyPass::getAnalysisUsage(AnalysisUsage &AU) const {
1895 AU.setPreservesAll();
1896 AU.addRequired<MemorySSAWrapperPass>();
1897}
1898
1899bool MemorySSAPrinterLegacyPass::runOnFunction(Function &F) {
1900 auto &MSSA = getAnalysis<MemorySSAWrapperPass>().getMSSA();
1901 MSSA.print(dbgs());
1902 if (VerifyMemorySSA)
1903 MSSA.verifyMemorySSA();
1904 return false;
1905}
1906
1907AnalysisKey MemorySSAAnalysis::Key;
1908
1909MemorySSAAnalysis::Result MemorySSAAnalysis::run(Function &F,
1910 FunctionAnalysisManager &AM) {
1911 auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
1912 auto &AA = AM.getResult<AAManager>(F);
1913 return MemorySSAAnalysis::Result(llvm::make_unique<MemorySSA>(F, &AA, &DT));
1914}
1915
1916PreservedAnalyses MemorySSAPrinterPass::run(Function &F,
1917 FunctionAnalysisManager &AM) {
1918 OS << "MemorySSA for function: " << F.getName() << "\n";
1919 AM.getResult<MemorySSAAnalysis>(F).getMSSA().print(OS);
1920
1921 return PreservedAnalyses::all();
1922}
1923
1924PreservedAnalyses MemorySSAVerifierPass::run(Function &F,
1925 FunctionAnalysisManager &AM) {
1926 AM.getResult<MemorySSAAnalysis>(F).getMSSA().verifyMemorySSA();
1927
1928 return PreservedAnalyses::all();
1929}
1930
1931char MemorySSAWrapperPass::ID = 0;
1932
1933MemorySSAWrapperPass::MemorySSAWrapperPass() : FunctionPass(ID) {
1934 initializeMemorySSAWrapperPassPass(*PassRegistry::getPassRegistry());
1935}
1936
1937void MemorySSAWrapperPass::releaseMemory() { MSSA.reset(); }
1938
1939void MemorySSAWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
1940 AU.setPreservesAll();
1941 AU.addRequiredTransitive<DominatorTreeWrapperPass>();
1942 AU.addRequiredTransitive<AAResultsWrapperPass>();
1943}
1944
1945bool MemorySSAWrapperPass::runOnFunction(Function &F) {
1946 auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1947 auto &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
1948 MSSA.reset(new MemorySSA(F, &AA, &DT));
1949 return false;
1950}
1951
1952void MemorySSAWrapperPass::verifyAnalysis() const { MSSA->verifyMemorySSA(); }
1953
1954void MemorySSAWrapperPass::print(raw_ostream &OS, const Module *M) const {
1955 MSSA->print(OS);
1956}
1957
1958MemorySSAWalker::MemorySSAWalker(MemorySSA *M) : MSSA(M) {}
1959
1960MemorySSA::CachingWalker::CachingWalker(MemorySSA *M, AliasAnalysis *A,
1961 DominatorTree *D)
1962 : MemorySSAWalker(M), Walker(*M, *A, *D) {}
1963
1964void MemorySSA::CachingWalker::invalidateInfo(MemoryAccess *MA) {
1965 if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
1966 MUD->resetOptimized();
1967}
1968
1969/// \brief Walk the use-def chains starting at \p MA and find
1970/// the MemoryAccess that actually clobbers Loc.
1971///
1972/// \returns our clobbering memory access
1973MemoryAccess *MemorySSA::CachingWalker::getClobberingMemoryAccess(
1974 MemoryAccess *StartingAccess, UpwardsMemoryQuery &Q) {
1975 MemoryAccess *New = Walker.findClobber(StartingAccess, Q);
1976#ifdef EXPENSIVE_CHECKS
1977 MemoryAccess *NewNoCache = Walker.findClobber(StartingAccess, Q);
1978 assert(NewNoCache == New && "Cache made us hand back a different result?")(static_cast <bool> (NewNoCache == New && "Cache made us hand back a different result?"
) ? void (0) : __assert_fail ("NewNoCache == New && \"Cache made us hand back a different result?\""
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/Analysis/MemorySSA.cpp"
, 1978, __extension__ __PRETTY_FUNCTION__))
;
1979 (void)NewNoCache;
1980#endif
1981 if (AutoResetWalker)
1982 resetClobberWalker();
1983 return New;
1984}
1985
1986MemoryAccess *MemorySSA::CachingWalker::getClobberingMemoryAccess(
1987 MemoryAccess *StartingAccess, const MemoryLocation &Loc) {
1988 if (isa<MemoryPhi>(StartingAccess))
1989 return StartingAccess;
1990
1991 auto *StartingUseOrDef = cast<MemoryUseOrDef>(StartingAccess);
1992 if (MSSA->isLiveOnEntryDef(StartingUseOrDef))
1993 return StartingUseOrDef;
1994
1995 Instruction *I = StartingUseOrDef->getMemoryInst();
1996
1997 // Conservatively, fences are always clobbers, so don't perform the walk if we
1998 // hit a fence.
1999 if (!ImmutableCallSite(I) && I->isFenceLike())
2000 return StartingUseOrDef;
2001
2002 UpwardsMemoryQuery Q;
2003 Q.OriginalAccess = StartingUseOrDef;
2004 Q.StartingLoc = Loc;
2005 Q.Inst = I;
2006 Q.IsCall = false;
2007
2008 // Unlike the other function, do not walk to the def of a def, because we are
2009 // handed something we already believe is the clobbering access.
2010 MemoryAccess *DefiningAccess = isa<MemoryUse>(StartingUseOrDef)
2011 ? StartingUseOrDef->getDefiningAccess()
2012 : StartingUseOrDef;
2013
2014 MemoryAccess *Clobber = getClobberingMemoryAccess(DefiningAccess, Q);
2015 DEBUG(dbgs() << "Starting Memory SSA clobber for " << *I << " is ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "Starting Memory SSA clobber for "
<< *I << " is "; } } while (false)
;
2016 DEBUG(dbgs() << *StartingUseOrDef << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << *StartingUseOrDef << "\n"
; } } while (false)
;
2017 DEBUG(dbgs() << "Final Memory SSA clobber for " << *I << " is ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "Final Memory SSA clobber for "
<< *I << " is "; } } while (false)
;
2018 DEBUG(dbgs() << *Clobber << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << *Clobber << "\n"; } } while
(false)
;
2019 return Clobber;
2020}
2021
2022MemoryAccess *
2023MemorySSA::CachingWalker::getClobberingMemoryAccess(MemoryAccess *MA) {
2024 auto *StartingAccess = dyn_cast<MemoryUseOrDef>(MA);
2025 // If this is a MemoryPhi, we can't do anything.
2026 if (!StartingAccess)
2027 return MA;
2028
2029 // If this is an already optimized use or def, return the optimized result.
2030 // Note: Currently, we do not store the optimized def result because we'd need
2031 // a separate field, since we can't use it as the defining access.
2032 if (auto *MUD = dyn_cast<MemoryUseOrDef>(StartingAccess))
2033 if (MUD->isOptimized())
2034 return MUD->getOptimized();
2035
2036 const Instruction *I = StartingAccess->getMemoryInst();
2037 UpwardsMemoryQuery Q(I, StartingAccess);
2038 // We can't sanely do anything with a fences, they conservatively
2039 // clobber all memory, and have no locations to get pointers from to
2040 // try to disambiguate.
2041 if (!Q.IsCall && I->isFenceLike())
2042 return StartingAccess;
2043
2044 if (isUseTriviallyOptimizableToLiveOnEntry(*MSSA->AA, I)) {
2045 MemoryAccess *LiveOnEntry = MSSA->getLiveOnEntryDef();
2046 if (auto *MUD = dyn_cast<MemoryUseOrDef>(StartingAccess))
2047 MUD->setOptimized(LiveOnEntry);
2048 return LiveOnEntry;
2049 }
2050
2051 // Start with the thing we already think clobbers this location
2052 MemoryAccess *DefiningAccess = StartingAccess->getDefiningAccess();
2053
2054 // At this point, DefiningAccess may be the live on entry def.
2055 // If it is, we will not get a better result.
2056 if (MSSA->isLiveOnEntryDef(DefiningAccess))
2057 return DefiningAccess;
2058
2059 MemoryAccess *Result = getClobberingMemoryAccess(DefiningAccess, Q);
2060 DEBUG(dbgs() << "Starting Memory SSA clobber for " << *I << " is ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "Starting Memory SSA clobber for "
<< *I << " is "; } } while (false)
;
2061 DEBUG(dbgs() << *DefiningAccess << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << *DefiningAccess << "\n"
; } } while (false)
;
2062 DEBUG(dbgs() << "Final Memory SSA clobber for " << *I << " is ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "Final Memory SSA clobber for "
<< *I << " is "; } } while (false)
;
2063 DEBUG(dbgs() << *Result << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << *Result << "\n"; } } while
(false)
;
2064 if (auto *MUD = dyn_cast<MemoryUseOrDef>(StartingAccess))
2065 MUD->setOptimized(Result);
2066
2067 return Result;
2068}
2069
2070MemoryAccess *
2071DoNothingMemorySSAWalker::getClobberingMemoryAccess(MemoryAccess *MA) {
2072 if (auto *Use = dyn_cast<MemoryUseOrDef>(MA))
2073 return Use->getDefiningAccess();
2074 return MA;
2075}
2076
2077MemoryAccess *DoNothingMemorySSAWalker::getClobberingMemoryAccess(
2078 MemoryAccess *StartingAccess, const MemoryLocation &) {
2079 if (auto *Use = dyn_cast<MemoryUseOrDef>(StartingAccess))
2080 return Use->getDefiningAccess();
2081 return StartingAccess;
2082}
2083
2084void MemoryPhi::deleteMe(DerivedUser *Self) {
2085 delete static_cast<MemoryPhi *>(Self);
2086}
2087
2088void MemoryDef::deleteMe(DerivedUser *Self) {
2089 delete static_cast<MemoryDef *>(Self);
2090}
2091
2092void MemoryUse::deleteMe(DerivedUser *Self) {
2093 delete static_cast<MemoryUse *>(Self);
2094}