/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp

Bug Summary

File:	llvm/lib/Analysis/MemorySSA.cpp
Warning:	line 2055, column 5 Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name MemorySSA.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -fno-split-dwarf-inlining -debugger-tuning=gdb -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-12/lib/clang/12.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/build-llvm/lib/Analysis -I /build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis -I /build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/build-llvm/include -I /build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-12/lib/clang/12.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/build-llvm/lib/Analysis -fdebug-prefix-map=/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -o /tmp/scan-build-2020-12-17-211521-24385-1 -x c++ /build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp

/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp

→

1//===- MemorySSA.cpp - Memory SSA Builder ---------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements the MemorySSA class.
10//
11//===----------------------------------------------------------------------===//

13#include "llvm/Analysis/MemorySSA.h"
14#include "llvm/ADT/DenseMap.h"
15#include "llvm/ADT/DenseMapInfo.h"
16#include "llvm/ADT/DenseSet.h"
17#include "llvm/ADT/DepthFirstIterator.h"
18#include "llvm/ADT/Hashing.h"
19#include "llvm/ADT/None.h"
20#include "llvm/ADT/Optional.h"
21#include "llvm/ADT/STLExtras.h"
22#include "llvm/ADT/SmallPtrSet.h"
23#include "llvm/ADT/SmallVector.h"
24#include "llvm/ADT/iterator.h"
25#include "llvm/ADT/iterator_range.h"
26#include "llvm/Analysis/AliasAnalysis.h"
27#include "llvm/Analysis/CFGPrinter.h"
28#include "llvm/Analysis/IteratedDominanceFrontier.h"
29#include "llvm/Analysis/MemoryLocation.h"
30#include "llvm/Config/llvm-config.h"
31#include "llvm/IR/AssemblyAnnotationWriter.h"
32#include "llvm/IR/BasicBlock.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/InitializePasses.h"
43#include "llvm/Pass.h"
44#include "llvm/Support/AtomicOrdering.h"
45#include "llvm/Support/Casting.h"
46#include "llvm/Support/CommandLine.h"
47#include "llvm/Support/Compiler.h"
48#include "llvm/Support/Debug.h"
49#include "llvm/Support/ErrorHandling.h"
50#include "llvm/Support/FormattedStream.h"
51#include "llvm/Support/raw_ostream.h"
52#include <algorithm>
53#include <cassert>
54#include <cstdlib>
55#include <iterator>
56#include <memory>
57#include <utility>

59using namespace llvm;

61#define DEBUG_TYPE"memoryssa" "memoryssa"

63static cl::opt<std::string>
  DotCFGMSSA("dot-cfg-mssa",
             cl::value_desc("file name for generated dot file"),
             cl::desc("file name for generated dot file"), cl::init(""));

68INITIALIZE_PASS_BEGIN(MemorySSAWrapperPass, "memoryssa", "Memory SSA", false,static void *initializeMemorySSAWrapperPassPassOnce(PassRegistry
 &Registry) {
                    true)static void *initializeMemorySSAWrapperPassPassOnce(PassRegistry
 &Registry) {
70INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);
71INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)initializeAAResultsWrapperPassPass(Registry);
72INITIALIZE_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))
; }
                  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))
; }

75INITIALIZE_PASS_BEGIN(MemorySSAPrinterLegacyPass, "print-memoryssa",static void *initializeMemorySSAPrinterLegacyPassPassOnce(PassRegistry
 &Registry) {
                    "Memory SSA Printer", false, false)static void *initializeMemorySSAPrinterLegacyPassPassOnce(PassRegistry
 &Registry) {
77INITIALIZE_PASS_DEPENDENCY(MemorySSAWrapperPass)initializeMemorySSAWrapperPassPass(Registry);
78INITIALIZE_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
)); }
                  "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
)); }

81static cl::opt<unsigned> MaxCheckLimit(
  "memssa-check-limit", cl::Hidden, cl::init(100),
  cl::desc("The maximum number of stores/phis MemorySSA"
           "will consider trying to walk past (default = 100)"));

86// Always verify MemorySSA if expensive checking is enabled.
87#ifdef EXPENSIVE_CHECKS
88bool llvm::VerifyMemorySSA = true;
89#else
90bool llvm::VerifyMemorySSA = false;
91#endif
92/// Enables memory ssa as a dependency for loop passes in legacy pass manager.
93cl::opt<bool> llvm::EnableMSSALoopDependency(
  "enable-mssa-loop-dependency", cl::Hidden, cl::init(true),
  cl::desc("Enable MemorySSA dependency for loop pass manager"));

97static cl::opt<bool, true>
  VerifyMemorySSAX("verify-memoryssa", cl::location(VerifyMemorySSA),
                   cl::Hidden, cl::desc("Enable verification of MemorySSA."));

101namespace llvm {

103/// An assembly annotator class to print Memory SSA information in
104/// comments.
105class MemorySSAAnnotatedWriter : public AssemblyAnnotationWriter {
friend class MemorySSA;

const MemorySSA *MSSA;

110public:
MemorySSAAnnotatedWriter(const MemorySSA *M) : MSSA(M) {}

void emitBasicBlockStartAnnot(const BasicBlock *BB,
                              formatted_raw_ostream &OS) override {
  if (MemoryAccess *MA = MSSA->getMemoryAccess(BB))
    OS << "; " << *MA << "\n";
}

void emitInstructionAnnot(const Instruction *I,
                          formatted_raw_ostream &OS) override {
  if (MemoryAccess *MA = MSSA->getMemoryAccess(I))
    OS << "; " << *MA << "\n";
}
124};

126} // end namespace llvm

128namespace {

130/// Our current alias analysis API differentiates heavily between calls and
131/// non-calls, and functions called on one usually assert on the other.
132/// This class encapsulates the distinction to simplify other code that wants
133/// "Memory affecting instructions and related data" to use as a key.
134/// For example, this class is used as a densemap key in the use optimizer.
135class MemoryLocOrCall {
136public:
bool IsCall = false;

MemoryLocOrCall(MemoryUseOrDef *MUD)
    : MemoryLocOrCall(MUD->getMemoryInst()) {}
MemoryLocOrCall(const MemoryUseOrDef *MUD)
    : MemoryLocOrCall(MUD->getMemoryInst()) {}

MemoryLocOrCall(Instruction *Inst) {
  if (auto *C = dyn_cast<CallBase>(Inst)) {
    IsCall = true;
    Call = C;
  } else {
    IsCall = false;
    // There is no such thing as a memorylocation for a fence inst, and it is
    // unique in that regard.
    if (!isa<FenceInst>(Inst))
      Loc = MemoryLocation::get(Inst);
  }
}

explicit MemoryLocOrCall(const MemoryLocation &Loc) : Loc(Loc) {}

const CallBase *getCall() const {
  assert(IsCall)((IsCall) ? static_cast<void> (0) : __assert_fail ("IsCall"
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 160, __PRETTY_FUNCTION__));
  return Call;
}

MemoryLocation getLoc() const {
  assert(!IsCall)((!IsCall) ? static_cast<void> (0) : __assert_fail ("!IsCall"
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 165, __PRETTY_FUNCTION__));
  return Loc;
}

bool operator==(const MemoryLocOrCall &Other) const {
  if (IsCall != Other.IsCall)
    return false;

  if (!IsCall)
    return Loc == Other.Loc;

  if (Call->getCalledOperand() != Other.Call->getCalledOperand())
    return false;

  return Call->arg_size() == Other.Call->arg_size() &&
         std::equal(Call->arg_begin(), Call->arg_end(),
                    Other.Call->arg_begin());
}

184private:
union {
  const CallBase *Call;
  MemoryLocation Loc;
};
189};

191} // end anonymous namespace

193namespace llvm {

195template <> struct DenseMapInfo<MemoryLocOrCall> {
static inline MemoryLocOrCall getEmptyKey() {
  return MemoryLocOrCall(DenseMapInfo<MemoryLocation>::getEmptyKey());
}

static inline MemoryLocOrCall getTombstoneKey() {
  return MemoryLocOrCall(DenseMapInfo<MemoryLocation>::getTombstoneKey());
}

static unsigned getHashValue(const MemoryLocOrCall &MLOC) {
  if (!MLOC.IsCall)
    return hash_combine(
        MLOC.IsCall,
        DenseMapInfo<MemoryLocation>::getHashValue(MLOC.getLoc()));

  hash_code hash =
      hash_combine(MLOC.IsCall, DenseMapInfo<const Value *>::getHashValue(
                                    MLOC.getCall()->getCalledOperand()));

  for (const Value *Arg : MLOC.getCall()->args())
    hash = hash_combine(hash, DenseMapInfo<const Value *>::getHashValue(Arg));
  return hash;
}

static bool isEqual(const MemoryLocOrCall &LHS, const MemoryLocOrCall &RHS) {
  return LHS == RHS;
}
222};

224} // end namespace llvm

226/// This does one-way checks to see if Use could theoretically be hoisted above
227/// MayClobber. This will not check the other way around.
228///
229/// This assumes that, for the purposes of MemorySSA, Use comes directly after
230/// MayClobber, with no potentially clobbering operations in between them.
231/// (Where potentially clobbering ops are memory barriers, aliased stores, etc.)
232static bool areLoadsReorderable(const LoadInst *Use,
                              const LoadInst *MayClobber) {
bool VolatileUse = Use->isVolatile();
bool VolatileClobber = MayClobber->isVolatile();
// Volatile operations may never be reordered with other volatile operations.
if (VolatileUse && VolatileClobber)
  return false;
// Otherwise, volatile doesn't matter here. From the language reference:
// 'optimizers may change the order of volatile operations relative to
// non-volatile operations.'"

// If a load is seq_cst, it cannot be moved above other loads. If its ordering
// is weaker, it can be moved above other loads. We just need to be sure that
// MayClobber isn't an acquire load, because loads can't be moved above
// acquire loads.
//
// Note that this explicitly *does* allow the free reordering of monotonic (or
// weaker) loads of the same address.
bool SeqCstUse = Use->getOrdering() == AtomicOrdering::SequentiallyConsistent;
bool MayClobberIsAcquire = isAtLeastOrStrongerThan(MayClobber->getOrdering(),
                                                   AtomicOrdering::Acquire);
return !(SeqCstUse || MayClobberIsAcquire);
254}

256namespace {

258struct ClobberAlias {
bool IsClobber;
Optional<AliasResult> AR;
261};

263} // end anonymous namespace

265// Return a pair of {IsClobber (bool), AR (AliasResult)}. It relies on AR being
266// ignored if IsClobber = false.
267template <typename AliasAnalysisType>
268static ClobberAlias
269instructionClobbersQuery(const MemoryDef *MD, const MemoryLocation &UseLoc,
                       const Instruction *UseInst, AliasAnalysisType &AA) {
Instruction *DefInst = MD->getMemoryInst();
assert(DefInst && "Defining instruction not actually an instruction")((DefInst && "Defining instruction not actually an instruction"
) ? static_cast<void> (0) : __assert_fail ("DefInst && \"Defining instruction not actually an instruction\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 272, __PRETTY_FUNCTION__));
Optional<AliasResult> AR;

if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(DefInst)) {
  // These intrinsics will show up as affecting memory, but they are just
  // markers, mostly.
  //
  // FIXME: We probably don't actually want MemorySSA to model these at all
  // (including creating MemoryAccesses for them): we just end up inventing
  // clobbers where they don't really exist at all. Please see D43269 for
  // context.
  switch (II->getIntrinsicID()) {
  case Intrinsic::lifetime_end:
  case Intrinsic::invariant_start:
  case Intrinsic::invariant_end:
  case Intrinsic::assume:
    return {false, NoAlias};
  case Intrinsic::dbg_addr:
  case Intrinsic::dbg_declare:
  case Intrinsic::dbg_label:
  case Intrinsic::dbg_value:
    llvm_unreachable("debuginfo shouldn't have associated defs!")::llvm::llvm_unreachable_internal("debuginfo shouldn't have associated defs!"
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 293);
  default:
    break;
  }
}

if (auto *CB = dyn_cast_or_null<CallBase>(UseInst)) {
  ModRefInfo I = AA.getModRefInfo(DefInst, CB);
  AR = isMustSet(I) ? MustAlias : MayAlias;
  return {isModOrRefSet(I), AR};
}

if (auto *DefLoad = dyn_cast<LoadInst>(DefInst))
  if (auto *UseLoad = dyn_cast_or_null<LoadInst>(UseInst))
    return {!areLoadsReorderable(UseLoad, DefLoad), MayAlias};

ModRefInfo I = AA.getModRefInfo(DefInst, UseLoc);
AR = isMustSet(I) ? MustAlias : MayAlias;
return {isModSet(I), AR};
312}

314template <typename AliasAnalysisType>
315static ClobberAlias instructionClobbersQuery(MemoryDef *MD,
                                           const MemoryUseOrDef *MU,
                                           const MemoryLocOrCall &UseMLOC,
                                           AliasAnalysisType &AA) {
// FIXME: This is a temporary hack to allow a single instructionClobbersQuery
// to exist while MemoryLocOrCall is pushed through places.
if (UseMLOC.IsCall)
  return instructionClobbersQuery(MD, MemoryLocation(), MU->getMemoryInst(),
                                  AA);
return instructionClobbersQuery(MD, UseMLOC.getLoc(), MU->getMemoryInst(),
                                AA);
326}

328// Return true when MD may alias MU, return false otherwise.
329bool MemorySSAUtil::defClobbersUseOrDef(MemoryDef *MD, const MemoryUseOrDef *MU,
                                      AliasAnalysis &AA) {
return instructionClobbersQuery(MD, MU, MemoryLocOrCall(MU), AA).IsClobber;
332}

334namespace {

336struct UpwardsMemoryQuery {
// True if our original query started off as a call
bool IsCall = false;
// The pointer location we started the query with. This will be empty if
// IsCall is true.
MemoryLocation StartingLoc;
// This is the instruction we were querying about.
const Instruction *Inst = nullptr;
// The MemoryAccess we actually got called with, used to test local domination
const MemoryAccess *OriginalAccess = nullptr;
Optional<AliasResult> AR = MayAlias;
bool SkipSelfAccess = false;

UpwardsMemoryQuery() = default;

UpwardsMemoryQuery(const Instruction *Inst, const MemoryAccess *Access)
    : IsCall(isa<CallBase>(Inst)), Inst(Inst), OriginalAccess(Access) {
  if (!IsCall)
    StartingLoc = MemoryLocation::get(Inst);
}
356};

358} // end anonymous namespace

360static bool lifetimeEndsAt(MemoryDef *MD, const MemoryLocation &Loc,
                         BatchAAResults &AA) {
Instruction *Inst = MD->getMemoryInst();
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
  switch (II->getIntrinsicID()) {
  case Intrinsic::lifetime_end: {
    MemoryLocation ArgLoc = MemoryLocation::getAfter(II->getArgOperand(1));
    return AA.alias(ArgLoc, Loc) == MustAlias;
  }
  default:
    return false;
  }
}
return false;
374}

376template <typename AliasAnalysisType>
377static bool isUseTriviallyOptimizableToLiveOnEntry(AliasAnalysisType &AA,
                                                 const Instruction *I) {
// If the memory can't be changed, then loads of the memory can't be
// clobbered.
if (auto *LI = dyn_cast<LoadInst>(I))
  return I->hasMetadata(LLVMContext::MD_invariant_load) ||
         AA.pointsToConstantMemory(MemoryLocation::get(LI));
return false;
385}

387/// Verifies that `Start` is clobbered by `ClobberAt`, and that nothing
388/// inbetween `Start` and `ClobberAt` can clobbers `Start`.
389///
390/// This is meant to be as simple and self-contained as possible. Because it
391/// uses no cache, etc., it can be relatively expensive.
392///
393/// \param Start     The MemoryAccess that we want to walk from.
394/// \param ClobberAt A clobber for Start.
395/// \param StartLoc  The MemoryLocation for Start.
396/// \param MSSA      The MemorySSA instance that Start and ClobberAt belong to.
397/// \param Query     The UpwardsMemoryQuery we used for our search.
398/// \param AA        The AliasAnalysis we used for our search.
399/// \param AllowImpreciseClobber Always false, unless we do relaxed verify.

401template <typename AliasAnalysisType>
402LLVM_ATTRIBUTE_UNUSED__attribute__((__unused__)) static void
403checkClobberSanity(const MemoryAccess *Start, MemoryAccess *ClobberAt,
                 const MemoryLocation &StartLoc, const MemorySSA &MSSA,
                 const UpwardsMemoryQuery &Query, AliasAnalysisType &AA,
                 bool AllowImpreciseClobber = false) {
assert(MSSA.dominates(ClobberAt, Start) && "Clobber doesn't dominate start?")((MSSA.dominates(ClobberAt, Start) && "Clobber doesn't dominate start?"
) ? static_cast<void> (0) : __assert_fail ("MSSA.dominates(ClobberAt, Start) && \"Clobber doesn't dominate start?\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 407, __PRETTY_FUNCTION__));

if (MSSA.isLiveOnEntryDef(Start)) {
  assert(MSSA.isLiveOnEntryDef(ClobberAt) &&((MSSA.isLiveOnEntryDef(ClobberAt) && "liveOnEntry must clobber itself"
) ? static_cast<void> (0) : __assert_fail ("MSSA.isLiveOnEntryDef(ClobberAt) && \"liveOnEntry must clobber itself\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 411, __PRETTY_FUNCTION__))
         "liveOnEntry must clobber itself")((MSSA.isLiveOnEntryDef(ClobberAt) && "liveOnEntry must clobber itself"
) ? static_cast<void> (0) : __assert_fail ("MSSA.isLiveOnEntryDef(ClobberAt) && \"liveOnEntry must clobber itself\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 411, __PRETTY_FUNCTION__));
  return;
}

bool FoundClobber = false;
DenseSet<ConstMemoryAccessPair> VisitedPhis;
SmallVector<ConstMemoryAccessPair, 8> Worklist;
Worklist.emplace_back(Start, StartLoc);
// Walk all paths from Start to ClobberAt, while looking for clobbers. If one
// is found, complain.
while (!Worklist.empty()) {
  auto MAP = Worklist.pop_back_val();
  // All we care about is that nothing from Start to ClobberAt clobbers Start.
  // We learn nothing from revisiting nodes.
  if (!VisitedPhis.insert(MAP).second)
    continue;

  for (const auto *MA : def_chain(MAP.first)) {
    if (MA == ClobberAt) {
      if (const auto *MD = dyn_cast<MemoryDef>(MA)) {
        // instructionClobbersQuery isn't essentially free, so don't use `|=`,
        // since it won't let us short-circuit.
        //
        // Also, note that this can't be hoisted out of the `Worklist` loop,
        // since MD may only act as a clobber for 1 of N MemoryLocations.
        FoundClobber = FoundClobber || MSSA.isLiveOnEntryDef(MD);
        if (!FoundClobber) {
          ClobberAlias CA =
              instructionClobbersQuery(MD, MAP.second, Query.Inst, AA);
          if (CA.IsClobber) {
            FoundClobber = true;
            // Not used: CA.AR;
          }
        }
      }
      break;
    }

    // We should never hit liveOnEntry, unless it's the clobber.
    assert(!MSSA.isLiveOnEntryDef(MA) && "Hit liveOnEntry before clobber?")((!MSSA.isLiveOnEntryDef(MA) && "Hit liveOnEntry before clobber?"
) ? static_cast<void> (0) : __assert_fail ("!MSSA.isLiveOnEntryDef(MA) && \"Hit liveOnEntry before clobber?\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 450, __PRETTY_FUNCTION__));

    if (const auto *MD = dyn_cast<MemoryDef>(MA)) {
      // If Start is a Def, skip self.
      if (MD == Start)
        continue;

      assert(!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA)((!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA) .
IsClobber && "Found clobber before reaching ClobberAt!"
) ? static_cast<void> (0) : __assert_fail ("!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA) .IsClobber && \"Found clobber before reaching ClobberAt!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 459, __PRETTY_FUNCTION__))
                  .IsClobber &&((!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA) .
IsClobber && "Found clobber before reaching ClobberAt!"
) ? static_cast<void> (0) : __assert_fail ("!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA) .IsClobber && \"Found clobber before reaching ClobberAt!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 459, __PRETTY_FUNCTION__))
             "Found clobber before reaching ClobberAt!")((!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA) .
IsClobber && "Found clobber before reaching ClobberAt!"
) ? static_cast<void> (0) : __assert_fail ("!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA) .IsClobber && \"Found clobber before reaching ClobberAt!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 459, __PRETTY_FUNCTION__));
      continue;
    }

    if (const auto *MU = dyn_cast<MemoryUse>(MA)) {
      (void)MU;
      assert (MU == Start &&((MU == Start && "Can only find use in def chain if Start is a use"
) ? static_cast<void> (0) : __assert_fail ("MU == Start && \"Can only find use in def chain if Start is a use\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 466, __PRETTY_FUNCTION__))
              "Can only find use in def chain if Start is a use")((MU == Start && "Can only find use in def chain if Start is a use"
) ? static_cast<void> (0) : __assert_fail ("MU == Start && \"Can only find use in def chain if Start is a use\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 466, __PRETTY_FUNCTION__));
      continue;
    }

    assert(isa<MemoryPhi>(MA))((isa<MemoryPhi>(MA)) ? static_cast<void> (0) : __assert_fail
 ("isa<MemoryPhi>(MA)", "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 470, __PRETTY_FUNCTION__));

    // Add reachable phi predecessors
    for (auto ItB = upward_defs_begin(
                  {const_cast<MemoryAccess *>(MA), MAP.second},
                  MSSA.getDomTree()),
              ItE = upward_defs_end();
         ItB != ItE; ++ItB)
      if (MSSA.getDomTree().isReachableFromEntry(ItB.getPhiArgBlock()))
        Worklist.emplace_back(*ItB);
  }
}

// If the verify is done following an optimization, it's possible that
// ClobberAt was a conservative clobbering, that we can now infer is not a
// true clobbering access. Don't fail the verify if that's the case.
// We do have accesses that claim they're optimized, but could be optimized
// further. Updating all these can be expensive, so allow it for now (FIXME).
if (AllowImpreciseClobber)
  return;

// If ClobberAt is a MemoryPhi, we can assume something above it acted as a
// clobber. Otherwise, `ClobberAt` should've acted as a clobber at some point.
assert((isa<MemoryPhi>(ClobberAt) || FoundClobber) &&(((isa<MemoryPhi>(ClobberAt) || FoundClobber) &&
 "ClobberAt never acted as a clobber") ? static_cast<void>
 (0) : __assert_fail ("(isa<MemoryPhi>(ClobberAt) || FoundClobber) && \"ClobberAt never acted as a clobber\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 494, __PRETTY_FUNCTION__))
       "ClobberAt never acted as a clobber")(((isa<MemoryPhi>(ClobberAt) || FoundClobber) &&
 "ClobberAt never acted as a clobber") ? static_cast<void>
 (0) : __assert_fail ("(isa<MemoryPhi>(ClobberAt) || FoundClobber) && \"ClobberAt never acted as a clobber\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 494, __PRETTY_FUNCTION__));
495}

497namespace {

499/// Our algorithm for walking (and trying to optimize) clobbers, all wrapped up
500/// in one class.
501template <class AliasAnalysisType> class ClobberWalker {
/// Save a few bytes by using unsigned instead of size_t.
using ListIndex = unsigned;

/// Represents a span of contiguous MemoryDefs, potentially ending in a
/// MemoryPhi.
struct DefPath {
  MemoryLocation Loc;
  // Note that, because we always walk in reverse, Last will always dominate
  // First. Also note that First and Last are inclusive.
  MemoryAccess *First;
  MemoryAccess *Last;
  Optional<ListIndex> Previous;

  DefPath(const MemoryLocation &Loc, MemoryAccess *First, MemoryAccess *Last,
          Optional<ListIndex> Previous)
      : Loc(Loc), First(First), Last(Last), Previous(Previous) {}

  DefPath(const MemoryLocation &Loc, MemoryAccess *Init,
          Optional<ListIndex> Previous)
      : DefPath(Loc, Init, Init, Previous) {}
};

const MemorySSA &MSSA;
AliasAnalysisType &AA;
DominatorTree &DT;
UpwardsMemoryQuery *Query;
unsigned *UpwardWalkLimit;

// Phi optimization bookkeeping:
// List of DefPath to process during the current phi optimization walk.
SmallVector<DefPath, 32> Paths;
// List of visited <Access, Location> pairs; we can skip paths already
// visited with the same memory location.
DenseSet<ConstMemoryAccessPair> VisitedPhis;
// Record if phi translation has been performed during the current phi
// optimization walk, as merging alias results after phi translation can
// yield incorrect results. Context in PR46156.
bool PerformedPhiTranslation = false;

/// Find the nearest def or phi that `From` can legally be optimized to.
const MemoryAccess *getWalkTarget(const MemoryPhi *From) const {
  assert(From->getNumOperands() && "Phi with no operands?")((From->getNumOperands() && "Phi with no operands?"
) ? static_cast<void> (0) : __assert_fail ("From->getNumOperands() && \"Phi with no operands?\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 543, __PRETTY_FUNCTION__));

  BasicBlock *BB = From->getBlock();
  MemoryAccess *Result = MSSA.getLiveOnEntryDef();
  DomTreeNode *Node = DT.getNode(BB);
  while ((Node = Node->getIDom())) {
    auto *Defs = MSSA.getBlockDefs(Node->getBlock());
    if (Defs)
      return &*Defs->rbegin();
  }
  return Result;
}

/// Result of calling walkToPhiOrClobber.
struct UpwardsWalkResult {
  /// The "Result" of the walk. Either a clobber, the last thing we walked, or
  /// both. Include alias info when clobber found.
  MemoryAccess *Result;
  bool IsKnownClobber;
  Optional<AliasResult> AR;
};

/// Walk to the next Phi or Clobber in the def chain starting at Desc.Last.
/// This will update Desc.Last as it walks. It will (optionally) also stop at
/// StopAt.
///
/// This does not test for whether StopAt is a clobber
UpwardsWalkResult
walkToPhiOrClobber(DefPath &Desc, const MemoryAccess *StopAt = nullptr,
                   const MemoryAccess *SkipStopAt = nullptr) const {
  assert(!isa<MemoryUse>(Desc.Last) && "Uses don't exist in my world")((!isa<MemoryUse>(Desc.Last) && "Uses don't exist in my world"
) ? static_cast<void> (0) : __assert_fail ("!isa<MemoryUse>(Desc.Last) && \"Uses don't exist in my world\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 573, __PRETTY_FUNCTION__));
  assert(UpwardWalkLimit && "Need a valid walk limit")((UpwardWalkLimit && "Need a valid walk limit") ? static_cast
<void> (0) : __assert_fail ("UpwardWalkLimit && \"Need a valid walk limit\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 574, __PRETTY_FUNCTION__));
  bool LimitAlreadyReached = false;
  // (*UpwardWalkLimit) may be 0 here, due to the loop in tryOptimizePhi. Set
  // it to 1. This will not do any alias() calls. It either returns in the
  // first iteration in the loop below, or is set back to 0 if all def chains
  // are free of MemoryDefs.
  if (!*UpwardWalkLimit) {
    *UpwardWalkLimit = 1;
    LimitAlreadyReached = true;
  }

  for (MemoryAccess *Current : def_chain(Desc.Last)) {
    Desc.Last = Current;
    if (Current == StopAt || Current == SkipStopAt)
      return {Current, false, MayAlias};

    if (auto *MD = dyn_cast<MemoryDef>(Current)) {
      if (MSSA.isLiveOnEntryDef(MD))
        return {MD, true, MustAlias};

      if (!--*UpwardWalkLimit)
        return {Current, true, MayAlias};

      ClobberAlias CA =
          instructionClobbersQuery(MD, Desc.Loc, Query->Inst, AA);
      if (CA.IsClobber)
        return {MD, true, CA.AR};
    }
  }

  if (LimitAlreadyReached)
    *UpwardWalkLimit = 0;

  assert(isa<MemoryPhi>(Desc.Last) &&((isa<MemoryPhi>(Desc.Last) && "Ended at a non-clobber that's not a phi?"
) ? static_cast<void> (0) : __assert_fail ("isa<MemoryPhi>(Desc.Last) && \"Ended at a non-clobber that's not a phi?\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 608, __PRETTY_FUNCTION__))
         "Ended at a non-clobber that's not a phi?")((isa<MemoryPhi>(Desc.Last) && "Ended at a non-clobber that's not a phi?"
) ? static_cast<void> (0) : __assert_fail ("isa<MemoryPhi>(Desc.Last) && \"Ended at a non-clobber that's not a phi?\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 608, __PRETTY_FUNCTION__));
  return {Desc.Last, false, MayAlias};
}

void addSearches(MemoryPhi *Phi, SmallVectorImpl<ListIndex> &PausedSearches,
                 ListIndex PriorNode) {
  auto UpwardDefsBegin = upward_defs_begin({Phi, Paths[PriorNode].Loc}, DT,
                                           &PerformedPhiTranslation);
  auto UpwardDefs = make_range(UpwardDefsBegin, upward_defs_end());
  for (const MemoryAccessPair &P : UpwardDefs) {
    PausedSearches.push_back(Paths.size());
    Paths.emplace_back(P.second, P.first, PriorNode);
  }
}

/// Represents a search that terminated after finding a clobber. This clobber
/// may or may not be present in the path of defs from LastNode..SearchStart,
/// since it may have been retrieved from cache.
struct TerminatedPath {
  MemoryAccess *Clobber;
  ListIndex LastNode;
};

/// Get an access that keeps us from optimizing to the given phi.
///
/// PausedSearches is an array of indices into the Paths array. Its incoming
/// value is the indices of searches that stopped at the last phi optimization
/// target. It's left in an unspecified state.
///
/// If this returns None, NewPaused is a vector of searches that terminated
/// at StopWhere. Otherwise, NewPaused is left in an unspecified state.
Optional<TerminatedPath>
getBlockingAccess(const MemoryAccess *StopWhere,
                  SmallVectorImpl<ListIndex> &PausedSearches,
                  SmallVectorImpl<ListIndex> &NewPaused,
                  SmallVectorImpl<TerminatedPath> &Terminated) {
  assert(!PausedSearches.empty() && "No searches to continue?")((!PausedSearches.empty() && "No searches to continue?"
) ? static_cast<void> (0) : __assert_fail ("!PausedSearches.empty() && \"No searches to continue?\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 644, __PRETTY_FUNCTION__));

  // BFS vs DFS really doesn't make a difference here, so just do a DFS with
  // PausedSearches as our stack.
  while (!PausedSearches.empty()) {
    ListIndex PathIndex = PausedSearches.pop_back_val();
    DefPath &Node = Paths[PathIndex];

    // If we've already visited this path with this MemoryLocation, we don't
    // need to do so again.
    //
    // NOTE: That we just drop these paths on the ground makes caching
    // behavior sporadic. e.g. given a diamond:
    //  A
    // B C
    //  D
    //
    // ...If we walk D, B, A, C, we'll only cache the result of phi
    // optimization for A, B, and D; C will be skipped because it dies here.
    // This arguably isn't the worst thing ever, since:
    //   - We generally query things in a top-down order, so if we got below D
    //     without needing cache entries for {C, MemLoc}, then chances are
    //     that those cache entries would end up ultimately unused.
    //   - We still cache things for A, so C only needs to walk up a bit.
    // If this behavior becomes problematic, we can fix without a ton of extra
    // work.
    if (!VisitedPhis.insert({Node.Last, Node.Loc}).second) {
      if (PerformedPhiTranslation) {
        // If visiting this path performed Phi translation, don't continue,
        // since it may not be correct to merge results from two paths if one
        // relies on the phi translation.
        TerminatedPath Term{Node.Last, PathIndex};
        return Term;
      }
      continue;
    }

    const MemoryAccess *SkipStopWhere = nullptr;
    if (Query->SkipSelfAccess && Node.Loc == Query->StartingLoc) {
      assert(isa<MemoryDef>(Query->OriginalAccess))((isa<MemoryDef>(Query->OriginalAccess)) ? static_cast
<void> (0) : __assert_fail ("isa<MemoryDef>(Query->OriginalAccess)"
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 683, __PRETTY_FUNCTION__));
      SkipStopWhere = Query->OriginalAccess;
    }

    UpwardsWalkResult Res = walkToPhiOrClobber(Node,
                                               /*StopAt=*/StopWhere,
                                               /*SkipStopAt=*/SkipStopWhere);
    if (Res.IsKnownClobber) {
      assert(Res.Result != StopWhere && Res.Result != SkipStopWhere)((Res.Result != StopWhere && Res.Result != SkipStopWhere
) ? static_cast<void> (0) : __assert_fail ("Res.Result != StopWhere && Res.Result != SkipStopWhere"
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 691, __PRETTY_FUNCTION__));

      // If this wasn't a cache hit, we hit a clobber when walking. That's a
      // failure.
      TerminatedPath Term{Res.Result, PathIndex};
      if (!MSSA.dominates(Res.Result, StopWhere))
        return Term;

      // Otherwise, it's a valid thing to potentially optimize to.
      Terminated.push_back(Term);
      continue;
    }

    if (Res.Result == StopWhere || Res.Result == SkipStopWhere) {
      // We've hit our target. Save this path off for if we want to continue
      // walking. If we are in the mode of skipping the OriginalAccess, and
      // we've reached back to the OriginalAccess, do not save path, we've
      // just looped back to self.
      if (Res.Result != SkipStopWhere)
        NewPaused.push_back(PathIndex);
      continue;
    }

    assert(!MSSA.isLiveOnEntryDef(Res.Result) && "liveOnEntry is a clobber")((!MSSA.isLiveOnEntryDef(Res.Result) && "liveOnEntry is a clobber"
) ? static_cast<void> (0) : __assert_fail ("!MSSA.isLiveOnEntryDef(Res.Result) && \"liveOnEntry is a clobber\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 714, __PRETTY_FUNCTION__));
    addSearches(cast<MemoryPhi>(Res.Result), PausedSearches, PathIndex);
  }

  return None;
}

template <typename T, typename Walker>
struct generic_def_path_iterator
    : public iterator_facade_base<generic_def_path_iterator<T, Walker>,
                                  std::forward_iterator_tag, T *> {
  generic_def_path_iterator() {}
  generic_def_path_iterator(Walker *W, ListIndex N) : W(W), N(N) {}

  T &operator*() const { return curNode(); }

  generic_def_path_iterator &operator++() {
    N = curNode().Previous;
    return *this;
  }

  bool operator==(const generic_def_path_iterator &O) const {
    if (N.hasValue() != O.N.hasValue())
      return false;
    return !N.hasValue() || *N == *O.N;
  }

private:
  T &curNode() const { return W->Paths[*N]; }

  Walker *W = nullptr;
  Optional<ListIndex> N = None;
};

using def_path_iterator = generic_def_path_iterator<DefPath, ClobberWalker>;
using const_def_path_iterator =
    generic_def_path_iterator<const DefPath, const ClobberWalker>;

iterator_range<def_path_iterator> def_path(ListIndex From) {
  return make_range(def_path_iterator(this, From), def_path_iterator());
}

iterator_range<const_def_path_iterator> const_def_path(ListIndex From) const {
  return make_range(const_def_path_iterator(this, From),
                    const_def_path_iterator());
}

struct OptznResult {
  /// The path that contains our result.
  TerminatedPath PrimaryClobber;
  /// The paths that we can legally cache back from, but that aren't
  /// necessarily the result of the Phi optimization.
  SmallVector<TerminatedPath, 4> OtherClobbers;
};

ListIndex defPathIndex(const DefPath &N) const {
  // The assert looks nicer if we don't need to do &N
  const DefPath *NP = &N;
  assert(!Paths.empty() && NP >= &Paths.front() && NP <= &Paths.back() &&((!Paths.empty() && NP >= &Paths.front() &&
 NP <= &Paths.back() && "Out of bounds DefPath!"
) ? static_cast<void> (0) : __assert_fail ("!Paths.empty() && NP >= &Paths.front() && NP <= &Paths.back() && \"Out of bounds DefPath!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 773, __PRETTY_FUNCTION__))
         "Out of bounds DefPath!")((!Paths.empty() && NP >= &Paths.front() &&
 NP <= &Paths.back() && "Out of bounds DefPath!"
) ? static_cast<void> (0) : __assert_fail ("!Paths.empty() && NP >= &Paths.front() && NP <= &Paths.back() && \"Out of bounds DefPath!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 773, __PRETTY_FUNCTION__));
  return NP - &Paths.front();
}

/// Try to optimize a phi as best as we can. Returns a SmallVector of Paths
/// that act as legal clobbers. Note that this won't return *all* clobbers.
///
/// Phi optimization algorithm tl;dr:
///   - Find the earliest def/phi, A, we can optimize to
///   - Find if all paths from the starting memory access ultimately reach A
///     - If not, optimization isn't possible.
///     - Otherwise, walk from A to another clobber or phi, A'.
///       - If A' is a def, we're done.
///       - If A' is a phi, try to optimize it.
///
/// A path is a series of {MemoryAccess, MemoryLocation} pairs. A path
/// terminates when a MemoryAccess that clobbers said MemoryLocation is found.
OptznResult tryOptimizePhi(MemoryPhi *Phi, MemoryAccess *Start,
                           const MemoryLocation &Loc) {
  assert(Paths.empty() && VisitedPhis.empty() && !PerformedPhiTranslation &&((Paths.empty() && VisitedPhis.empty() && !PerformedPhiTranslation
 && "Reset the optimization state.") ? static_cast<
void> (0) : __assert_fail ("Paths.empty() && VisitedPhis.empty() && !PerformedPhiTranslation && \"Reset the optimization state.\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 793, __PRETTY_FUNCTION__))
         "Reset the optimization state.")((Paths.empty() && VisitedPhis.empty() && !PerformedPhiTranslation
 && "Reset the optimization state.") ? static_cast<
void> (0) : __assert_fail ("Paths.empty() && VisitedPhis.empty() && !PerformedPhiTranslation && \"Reset the optimization state.\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 793, __PRETTY_FUNCTION__));

  Paths.emplace_back(Loc, Start, Phi, None);
  // Stores how many "valid" optimization nodes we had prior to calling
  // addSearches/getBlockingAccess. Necessary for caching if we had a blocker.
  auto PriorPathsSize = Paths.size();

  SmallVector<ListIndex, 16> PausedSearches;
  SmallVector<ListIndex, 8> NewPaused;
  SmallVector<TerminatedPath, 4> TerminatedPaths;

  addSearches(Phi, PausedSearches, 0);

  // Moves the TerminatedPath with the "most dominated" Clobber to the end of
  // Paths.
  auto MoveDominatedPathToEnd = [&](SmallVectorImpl<TerminatedPath> &Paths) {
    assert(!Paths.empty() && "Need a path to move")((!Paths.empty() && "Need a path to move") ? static_cast
<void> (0) : __assert_fail ("!Paths.empty() && \"Need a path to move\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 809, __PRETTY_FUNCTION__));
    auto Dom = Paths.begin();
    for (auto I = std::next(Dom), E = Paths.end(); I != E; ++I)
      if (!MSSA.dominates(I->Clobber, Dom->Clobber))
        Dom = I;
    auto Last = Paths.end() - 1;
    if (Last != Dom)
      std::iter_swap(Last, Dom);
  };

  MemoryPhi *Current = Phi;
  while (true) {
    assert(!MSSA.isLiveOnEntryDef(Current) &&((!MSSA.isLiveOnEntryDef(Current) && "liveOnEntry wasn't treated as a clobber?"
) ? static_cast<void> (0) : __assert_fail ("!MSSA.isLiveOnEntryDef(Current) && \"liveOnEntry wasn't treated as a clobber?\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 822, __PRETTY_FUNCTION__))
           "liveOnEntry wasn't treated as a clobber?")((!MSSA.isLiveOnEntryDef(Current) && "liveOnEntry wasn't treated as a clobber?"
) ? static_cast<void> (0) : __assert_fail ("!MSSA.isLiveOnEntryDef(Current) && \"liveOnEntry wasn't treated as a clobber?\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 822, __PRETTY_FUNCTION__));

    const auto *Target = getWalkTarget(Current);
    // If a TerminatedPath doesn't dominate Target, then it wasn't a legal
    // optimization for the prior phi.
    assert(all_of(TerminatedPaths, [&](const TerminatedPath &P) {((all_of(TerminatedPaths, [&](const TerminatedPath &P
) { return MSSA.dominates(P.Clobber, Target); })) ? static_cast
<void> (0) : __assert_fail ("all_of(TerminatedPaths, [&](const TerminatedPath &P) { return MSSA.dominates(P.Clobber, Target); })"
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 829, __PRETTY_FUNCTION__))
      return MSSA.dominates(P.Clobber, Target);((all_of(TerminatedPaths, [&](const TerminatedPath &P
) { return MSSA.dominates(P.Clobber, Target); })) ? static_cast
<void> (0) : __assert_fail ("all_of(TerminatedPaths, [&](const TerminatedPath &P) { return MSSA.dominates(P.Clobber, Target); })"
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 829, __PRETTY_FUNCTION__))
    }))((all_of(TerminatedPaths, [&](const TerminatedPath &P
) { return MSSA.dominates(P.Clobber, Target); })) ? static_cast
<void> (0) : __assert_fail ("all_of(TerminatedPaths, [&](const TerminatedPath &P) { return MSSA.dominates(P.Clobber, Target); })"
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 829, __PRETTY_FUNCTION__));

    // FIXME: This is broken, because the Blocker may be reported to be
    // liveOnEntry, and we'll happily wait for that to disappear (read: never)
    // For the moment, this is fine, since we do nothing with blocker info.
    if (Optional<TerminatedPath> Blocker = getBlockingAccess(
            Target, PausedSearches, NewPaused, TerminatedPaths)) {

      // Find the node we started at. We can't search based on N->Last, since
      // we may have gone around a loop with a different MemoryLocation.
      auto Iter = find_if(def_path(Blocker->LastNode), [&](const DefPath &N) {
        return defPathIndex(N) < PriorPathsSize;
      });
      assert(Iter != def_path_iterator())((Iter != def_path_iterator()) ? static_cast<void> (0) :
 __assert_fail ("Iter != def_path_iterator()", "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 842, __PRETTY_FUNCTION__));

      DefPath &CurNode = *Iter;
      assert(CurNode.Last == Current)((CurNode.Last == Current) ? static_cast<void> (0) : __assert_fail
 ("CurNode.Last == Current", "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 845, __PRETTY_FUNCTION__));

      // Two things:
      // A. We can't reliably cache all of NewPaused back. Consider a case
      //    where we have two paths in NewPaused; one of which can't optimize
      //    above this phi, whereas the other can. If we cache the second path
      //    back, we'll end up with suboptimal cache entries. We can handle
      //    cases like this a bit better when we either try to find all
      //    clobbers that block phi optimization, or when our cache starts
      //    supporting unfinished searches.
      // B. We can't reliably cache TerminatedPaths back here without doing
      //    extra checks; consider a case like:
      //       T
      //      / \
      //     D   C
      //      \ /
      //       S
      //    Where T is our target, C is a node with a clobber on it, D is a
      //    diamond (with a clobber *only* on the left or right node, N), and
      //    S is our start. Say we walk to D, through the node opposite N
      //    (read: ignoring the clobber), and see a cache entry in the top
      //    node of D. That cache entry gets put into TerminatedPaths. We then
      //    walk up to C (N is later in our worklist), find the clobber, and
      //    quit. If we append TerminatedPaths to OtherClobbers, we'll cache
      //    the bottom part of D to the cached clobber, ignoring the clobber
      //    in N. Again, this problem goes away if we start tracking all
      //    blockers for a given phi optimization.
      TerminatedPath Result{CurNode.Last, defPathIndex(CurNode)};
      return {Result, {}};
    }

    // If there's nothing left to search, then all paths led to valid clobbers
    // that we got from our cache; pick the nearest to the start, and allow
    // the rest to be cached back.
    if (NewPaused.empty()) {
      MoveDominatedPathToEnd(TerminatedPaths);
      TerminatedPath Result = TerminatedPaths.pop_back_val();
      return {Result, std::move(TerminatedPaths)};
    }

    MemoryAccess *DefChainEnd = nullptr;
    SmallVector<TerminatedPath, 4> Clobbers;
    for (ListIndex Paused : NewPaused) {
      UpwardsWalkResult WR = walkToPhiOrClobber(Paths[Paused]);
      if (WR.IsKnownClobber)
        Clobbers.push_back({WR.Result, Paused});
      else
        // Micro-opt: If we hit the end of the chain, save it.
        DefChainEnd = WR.Result;
    }

    if (!TerminatedPaths.empty()) {
      // If we couldn't find the dominating phi/liveOnEntry in the above loop,
      // do it now.
      if (!DefChainEnd)
        for (auto *MA : def_chain(const_cast<MemoryAccess *>(Target)))
          DefChainEnd = MA;
      assert(DefChainEnd && "Failed to find dominating phi/liveOnEntry")((DefChainEnd && "Failed to find dominating phi/liveOnEntry"
) ? static_cast<void> (0) : __assert_fail ("DefChainEnd && \"Failed to find dominating phi/liveOnEntry\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 902, __PRETTY_FUNCTION__));

      // If any of the terminated paths don't dominate the phi we'll try to
      // optimize, we need to figure out what they are and quit.
      const BasicBlock *ChainBB = DefChainEnd->getBlock();
      for (const TerminatedPath &TP : TerminatedPaths) {
        // Because we know that DefChainEnd is as "high" as we can go, we
        // don't need local dominance checks; BB dominance is sufficient.
        if (DT.dominates(ChainBB, TP.Clobber->getBlock()))
          Clobbers.push_back(TP);
      }
    }

    // If we have clobbers in the def chain, find the one closest to Current
    // and quit.
    if (!Clobbers.empty()) {
      MoveDominatedPathToEnd(Clobbers);
      TerminatedPath Result = Clobbers.pop_back_val();
      return {Result, std::move(Clobbers)};
    }

    assert(all_of(NewPaused,((all_of(NewPaused, [&](ListIndex I) { return Paths[I].Last
 == DefChainEnd; })) ? static_cast<void> (0) : __assert_fail
 ("all_of(NewPaused, [&](ListIndex I) { return Paths[I].Last == DefChainEnd; })"
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 924, __PRETTY_FUNCTION__))
                  [&](ListIndex I) { return Paths[I].Last == DefChainEnd; }))((all_of(NewPaused, [&](ListIndex I) { return Paths[I].Last
 == DefChainEnd; })) ? static_cast<void> (0) : __assert_fail
 ("all_of(NewPaused, [&](ListIndex I) { return Paths[I].Last == DefChainEnd; })"
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 924, __PRETTY_FUNCTION__));

    // Because liveOnEntry is a clobber, this must be a phi.
    auto *DefChainPhi = cast<MemoryPhi>(DefChainEnd);

    PriorPathsSize = Paths.size();
    PausedSearches.clear();
    for (ListIndex I : NewPaused)
      addSearches(DefChainPhi, PausedSearches, I);
    NewPaused.clear();

    Current = DefChainPhi;
  }
}

void verifyOptResult(const OptznResult &R) const {
  assert(all_of(R.OtherClobbers, [&](const TerminatedPath &P) {((all_of(R.OtherClobbers, [&](const TerminatedPath &P
) { return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber
); })) ? static_cast<void> (0) : __assert_fail ("all_of(R.OtherClobbers, [&](const TerminatedPath &P) { return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber); })"
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 942, __PRETTY_FUNCTION__))
    return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber);((all_of(R.OtherClobbers, [&](const TerminatedPath &P
) { return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber
); })) ? static_cast<void> (0) : __assert_fail ("all_of(R.OtherClobbers, [&](const TerminatedPath &P) { return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber); })"
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 942, __PRETTY_FUNCTION__))
  }))((all_of(R.OtherClobbers, [&](const TerminatedPath &P
) { return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber
); })) ? static_cast<void> (0) : __assert_fail ("all_of(R.OtherClobbers, [&](const TerminatedPath &P) { return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber); })"
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 942, __PRETTY_FUNCTION__));
}

void resetPhiOptznState() {
  Paths.clear();
  VisitedPhis.clear();
  PerformedPhiTranslation = false;
}

951public:
ClobberWalker(const MemorySSA &MSSA, AliasAnalysisType &AA, DominatorTree &DT)
    : MSSA(MSSA), AA(AA), DT(DT) {}

AliasAnalysisType *getAA() { return &AA; }
/// Finds the nearest clobber for the given query, optimizing phis if
/// possible.
MemoryAccess *findClobber(MemoryAccess *Start, UpwardsMemoryQuery &Q,
                          unsigned &UpWalkLimit) {
  Query = &Q;
  UpwardWalkLimit = &UpWalkLimit;
  // Starting limit must be > 0.
  if (!UpWalkLimit)
    UpWalkLimit++;

  MemoryAccess *Current = Start;
  // This walker pretends uses don't exist. If we're handed one, silently grab
  // its def. (This has the nice side-effect of ensuring we never cache uses)
  if (auto *MU = dyn_cast<MemoryUse>(Start))
    Current = MU->getDefiningAccess();

  DefPath FirstDesc(Q.StartingLoc, Current, Current, None);
  // Fast path for the overly-common case (no crazy phi optimization
  // necessary)
  UpwardsWalkResult WalkResult = walkToPhiOrClobber(FirstDesc);
  MemoryAccess *Result;
  if (WalkResult.IsKnownClobber) {
    Result = WalkResult.Result;
    Q.AR = WalkResult.AR;
  } else {
    OptznResult OptRes = tryOptimizePhi(cast<MemoryPhi>(FirstDesc.Last),
                                        Current, Q.StartingLoc);
    verifyOptResult(OptRes);
    resetPhiOptznState();
    Result = OptRes.PrimaryClobber.Clobber;
  }

988#ifdef EXPENSIVE_CHECKS
  if (!Q.SkipSelfAccess && *UpwardWalkLimit > 0)
    checkClobberSanity(Current, Result, Q.StartingLoc, MSSA, Q, AA);
991#endif
  return Result;
}
994};

996struct RenamePassData {
DomTreeNode *DTN;
DomTreeNode::const_iterator ChildIt;
MemoryAccess *IncomingVal;

RenamePassData(DomTreeNode *D, DomTreeNode::const_iterator It,
               MemoryAccess *M)
    : DTN(D), ChildIt(It), IncomingVal(M) {}

void swap(RenamePassData &RHS) {
  std::swap(DTN, RHS.DTN);
  std::swap(ChildIt, RHS.ChildIt);
  std::swap(IncomingVal, RHS.IncomingVal);
}
1010};

1012} // end anonymous namespace

1014namespace llvm {

1016template <class AliasAnalysisType> class MemorySSA::ClobberWalkerBase {
ClobberWalker<AliasAnalysisType> Walker;
MemorySSA *MSSA;

1020public:
ClobberWalkerBase(MemorySSA *M, AliasAnalysisType *A, DominatorTree *D)
    : Walker(*M, *A, *D), MSSA(M) {}

MemoryAccess *getClobberingMemoryAccessBase(MemoryAccess *,
                                            const MemoryLocation &,
                                            unsigned &);
// Third argument (bool), defines whether the clobber search should skip the
// original queried access. If true, there will be a follow-up query searching
// for a clobber access past "self". Note that the Optimized access is not
// updated if a new clobber is found by this SkipSelf search. If this
// additional query becomes heavily used we may decide to cache the result.
// Walker instantiations will decide how to set the SkipSelf bool.
MemoryAccess *getClobberingMemoryAccessBase(MemoryAccess *, unsigned &, bool);
1034};

1036/// A MemorySSAWalker that does AA walks to disambiguate accesses. It no
1037/// longer does caching on its own, but the name has been retained for the
1038/// moment.
1039template <class AliasAnalysisType>
1040class MemorySSA::CachingWalker final : public MemorySSAWalker {
ClobberWalkerBase<AliasAnalysisType> *Walker;

1043public:
CachingWalker(MemorySSA *M, ClobberWalkerBase<AliasAnalysisType> *W)
    : MemorySSAWalker(M), Walker(W) {}
~CachingWalker() override = default;

using MemorySSAWalker::getClobberingMemoryAccess;

MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA, unsigned &UWL) {
  return Walker->getClobberingMemoryAccessBase(MA, UWL, false);
}
MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA,
                                        const MemoryLocation &Loc,
                                        unsigned &UWL) {
  return Walker->getClobberingMemoryAccessBase(MA, Loc, UWL);
}

MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA) override {
  unsigned UpwardWalkLimit = MaxCheckLimit;
  return getClobberingMemoryAccess(MA, UpwardWalkLimit);
}
MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA,
                                        const MemoryLocation &Loc) override {
  unsigned UpwardWalkLimit = MaxCheckLimit;
  return getClobberingMemoryAccess(MA, Loc, UpwardWalkLimit);
}

void invalidateInfo(MemoryAccess *MA) override {
  if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
    MUD->resetOptimized();
}
1073};

1075template <class AliasAnalysisType>
1076class MemorySSA::SkipSelfWalker final : public MemorySSAWalker {
ClobberWalkerBase<AliasAnalysisType> *Walker;

1079public:
SkipSelfWalker(MemorySSA *M, ClobberWalkerBase<AliasAnalysisType> *W)
    : MemorySSAWalker(M), Walker(W) {}
~SkipSelfWalker() override = default;

using MemorySSAWalker::getClobberingMemoryAccess;

MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA, unsigned &UWL) {
  return Walker->getClobberingMemoryAccessBase(MA, UWL, true);
}
MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA,
                                        const MemoryLocation &Loc,
                                        unsigned &UWL) {
  return Walker->getClobberingMemoryAccessBase(MA, Loc, UWL);
}

MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA) override {
  unsigned UpwardWalkLimit = MaxCheckLimit;
  return getClobberingMemoryAccess(MA, UpwardWalkLimit);
}
MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA,
                                        const MemoryLocation &Loc) override {
  unsigned UpwardWalkLimit = MaxCheckLimit;
  return getClobberingMemoryAccess(MA, Loc, UpwardWalkLimit);
}

void invalidateInfo(MemoryAccess *MA) override {
  if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
    MUD->resetOptimized();
}
1109};

1111} // end namespace llvm

1113void MemorySSA::renameSuccessorPhis(BasicBlock *BB, MemoryAccess *IncomingVal,
                                  bool RenameAllUses) {
// Pass through values to our successors
for (const BasicBlock *S : successors(BB)) {
  auto It = PerBlockAccesses.find(S);
  // Rename the phi nodes in our successor block
  if (It == PerBlockAccesses.end() || !isa<MemoryPhi>(It->second->front()))
    continue;
  AccessList *Accesses = It->second.get();
  auto *Phi = cast<MemoryPhi>(&Accesses->front());
  if (RenameAllUses) {
    bool ReplacementDone = false;
    for (unsigned I = 0, E = Phi->getNumIncomingValues(); I != E; ++I)
      if (Phi->getIncomingBlock(I) == BB) {
        Phi->setIncomingValue(I, IncomingVal);
        ReplacementDone = true;
      }
    (void) ReplacementDone;
    assert(ReplacementDone && "Incomplete phi during partial rename")((ReplacementDone && "Incomplete phi during partial rename"
) ? static_cast<void> (0) : __assert_fail ("ReplacementDone && \"Incomplete phi during partial rename\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1131, __PRETTY_FUNCTION__));
  } else
    Phi->addIncoming(IncomingVal, BB);
}
1135}

1137/// Rename a single basic block into MemorySSA form.
1138/// Uses the standard SSA renaming algorithm.
1139/// \returns The new incoming value.
1140MemoryAccess *MemorySSA::renameBlock(BasicBlock *BB, MemoryAccess *IncomingVal,
                                   bool RenameAllUses) {
auto It = PerBlockAccesses.find(BB);
// Skip most processing if the list is empty.
if (It != PerBlockAccesses.end()) {
  AccessList *Accesses = It->second.get();
  for (MemoryAccess &L : *Accesses) {
    if (MemoryUseOrDef *MUD = dyn_cast<MemoryUseOrDef>(&L)) {
      if (MUD->getDefiningAccess() == nullptr || RenameAllUses)
        MUD->setDefiningAccess(IncomingVal);
      if (isa<MemoryDef>(&L))
        IncomingVal = &L;
    } else {
      IncomingVal = &L;
    }
  }
}
return IncomingVal;
1158}

1160/// This is the standard SSA renaming algorithm.
1161///
1162/// We walk the dominator tree in preorder, renaming accesses, and then filling
1163/// in phi nodes in our successors.
1164void MemorySSA::renamePass(DomTreeNode *Root, MemoryAccess *IncomingVal,
                         SmallPtrSetImpl<BasicBlock *> &Visited,
                         bool SkipVisited, bool RenameAllUses) {
assert(Root && "Trying to rename accesses in an unreachable block")((Root && "Trying to rename accesses in an unreachable block"
) ? static_cast<void> (0) : __assert_fail ("Root && \"Trying to rename accesses in an unreachable block\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1167, __PRETTY_FUNCTION__));

SmallVector<RenamePassData, 32> WorkStack;
// Skip everything if we already renamed this block and we are skipping.
// Note: You can't sink this into the if, because we need it to occur
// regardless of whether we skip blocks or not.
bool AlreadyVisited = !Visited.insert(Root->getBlock()).second;
if (SkipVisited && AlreadyVisited)
  return;

IncomingVal = renameBlock(Root->getBlock(), IncomingVal, RenameAllUses);
renameSuccessorPhis(Root->getBlock(), IncomingVal, RenameAllUses);
WorkStack.push_back({Root, Root->begin(), IncomingVal});

while (!WorkStack.empty()) {
  DomTreeNode *Node = WorkStack.back().DTN;
  DomTreeNode::const_iterator ChildIt = WorkStack.back().ChildIt;
  IncomingVal = WorkStack.back().IncomingVal;

  if (ChildIt == Node->end()) {
    WorkStack.pop_back();
  } else {
    DomTreeNode *Child = *ChildIt;
    ++WorkStack.back().ChildIt;
    BasicBlock *BB = Child->getBlock();
    // Note: You can't sink this into the if, because we need it to occur
    // regardless of whether we skip blocks or not.
    AlreadyVisited = !Visited.insert(BB).second;
    if (SkipVisited && AlreadyVisited) {
      // We already visited this during our renaming, which can happen when
      // being asked to rename multiple blocks. Figure out the incoming val,
      // which is the last def.
      // Incoming value can only change if there is a block def, and in that
      // case, it's the last block def in the list.
      if (auto *BlockDefs = getWritableBlockDefs(BB))
        IncomingVal = &*BlockDefs->rbegin();
    } else
      IncomingVal = renameBlock(BB, IncomingVal, RenameAllUses);
    renameSuccessorPhis(BB, IncomingVal, RenameAllUses);
    WorkStack.push_back({Child, Child->begin(), IncomingVal});
  }
}
1209}

1211/// This handles unreachable block accesses by deleting phi nodes in
1212/// unreachable blocks, and marking all other unreachable MemoryAccess's as
1213/// being uses of the live on entry definition.
1214void MemorySSA::markUnreachableAsLiveOnEntry(BasicBlock *BB) {
assert(!DT->isReachableFromEntry(BB) &&((!DT->isReachableFromEntry(BB) && "Reachable block found while handling unreachable blocks"
) ? static_cast<void> (0) : __assert_fail ("!DT->isReachableFromEntry(BB) && \"Reachable block found while handling unreachable blocks\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1216, __PRETTY_FUNCTION__))
       "Reachable block found while handling unreachable blocks")((!DT->isReachableFromEntry(BB) && "Reachable block found while handling unreachable blocks"
) ? static_cast<void> (0) : __assert_fail ("!DT->isReachableFromEntry(BB) && \"Reachable block found while handling unreachable blocks\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1216, __PRETTY_FUNCTION__));

// Make sure phi nodes in our reachable successors end up with a
// LiveOnEntryDef for our incoming edge, even though our block is forward
// unreachable.  We could just disconnect these blocks from the CFG fully,
// but we do not right now.
for (const BasicBlock *S : successors(BB)) {
  if (!DT->isReachableFromEntry(S))
    continue;
  auto It = PerBlockAccesses.find(S);
  // Rename the phi nodes in our successor block
  if (It == PerBlockAccesses.end() || !isa<MemoryPhi>(It->second->front()))
    continue;
  AccessList *Accesses = It->second.get();
  auto *Phi = cast<MemoryPhi>(&Accesses->front());
  Phi->addIncoming(LiveOnEntryDef.get(), BB);
}

auto It = PerBlockAccesses.find(BB);
if (It == PerBlockAccesses.end())
  return;

auto &Accesses = It->second;
for (auto AI = Accesses->begin(), AE = Accesses->end(); AI != AE;) {
  auto Next = std::next(AI);
  // If we have a phi, just remove it. We are going to replace all
  // users with live on entry.
  if (auto *UseOrDef = dyn_cast<MemoryUseOrDef>(AI))
    UseOrDef->setDefiningAccess(LiveOnEntryDef.get());
  else
    Accesses->erase(AI);
  AI = Next;
}
1249}

1251MemorySSA::MemorySSA(Function &Func, AliasAnalysis *AA, DominatorTree *DT)
  : AA(nullptr), DT(DT), F(Func), LiveOnEntryDef(nullptr), Walker(nullptr),
    SkipWalker(nullptr), NextID(0) {
// Build MemorySSA using a batch alias analysis. This reuses the internal
// state that AA collects during an alias()/getModRefInfo() call. This is
// safe because there are no CFG changes while building MemorySSA and can
// significantly reduce the time spent by the compiler in AA, because we will
// make queries about all the instructions in the Function.
assert(AA && "No alias analysis?")((AA && "No alias analysis?") ? static_cast<void>
 (0) : __assert_fail ("AA && \"No alias analysis?\"",
 "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1259, __PRETTY_FUNCTION__));
BatchAAResults BatchAA(*AA);
buildMemorySSA(BatchAA);
// Intentionally leave AA to nullptr while building so we don't accidently
// use non-batch AliasAnalysis.
this->AA = AA;
// Also create the walker here.
getWalker();
1267}

1269MemorySSA::~MemorySSA() {
// Drop all our references
for (const auto &Pair : PerBlockAccesses)
  for (MemoryAccess &MA : *Pair.second)
    MA.dropAllReferences();
1274}

1276MemorySSA::AccessList *MemorySSA::getOrCreateAccessList(const BasicBlock *BB) {
auto Res = PerBlockAccesses.insert(std::make_pair(BB, nullptr));

if (Res.second)
  Res.first->second = std::make_unique<AccessList>();
return Res.first->second.get();
1282}

1284MemorySSA::DefsList *MemorySSA::getOrCreateDefsList(const BasicBlock *BB) {
auto Res = PerBlockDefs.insert(std::make_pair(BB, nullptr));

if (Res.second)
  Res.first->second = std::make_unique<DefsList>();
return Res.first->second.get();
1290}

1292namespace llvm {

1294/// This class is a batch walker of all MemoryUse's in the program, and points
1295/// their defining access at the thing that actually clobbers them.  Because it
1296/// is a batch walker that touches everything, it does not operate like the
1297/// other walkers.  This walker is basically performing a top-down SSA renaming
1298/// pass, where the version stack is used as the cache.  This enables it to be
1299/// significantly more time and memory efficient than using the regular walker,
1300/// which is walking bottom-up.
1301class MemorySSA::OptimizeUses {
1302public:
OptimizeUses(MemorySSA *MSSA, CachingWalker<BatchAAResults> *Walker,
             BatchAAResults *BAA, DominatorTree *DT)
    : MSSA(MSSA), Walker(Walker), AA(BAA), DT(DT) {}

void optimizeUses();

1309private:
/// This represents where a given memorylocation is in the stack.
struct MemlocStackInfo {
  // This essentially is keeping track of versions of the stack. Whenever
  // the stack changes due to pushes or pops, these versions increase.
  unsigned long StackEpoch;
  unsigned long PopEpoch;
  // This is the lower bound of places on the stack to check. It is equal to
  // the place the last stack walk ended.
  // Note: Correctness depends on this being initialized to 0, which densemap
  // does
  unsigned long LowerBound;
  const BasicBlock *LowerBoundBlock;
  // This is where the last walk for this memory location ended.
  unsigned long LastKill;
  bool LastKillValid;
  Optional<AliasResult> AR;
};

void optimizeUsesInBlock(const BasicBlock *, unsigned long &, unsigned long &,
                         SmallVectorImpl<MemoryAccess *> &,
                         DenseMap<MemoryLocOrCall, MemlocStackInfo> &);

MemorySSA *MSSA;
CachingWalker<BatchAAResults> *Walker;
BatchAAResults *AA;
DominatorTree *DT;
1336};

1338} // end namespace llvm

1340/// Optimize the uses in a given block This is basically the SSA renaming
1341/// algorithm, with one caveat: We are able to use a single stack for all
1342/// MemoryUses.  This is because the set of *possible* reaching MemoryDefs is
1343/// the same for every MemoryUse.  The *actual* clobbering MemoryDef is just
1344/// going to be some position in that stack of possible ones.
1345///
1346/// We track the stack positions that each MemoryLocation needs
1347/// to check, and last ended at.  This is because we only want to check the
1348/// things that changed since last time.  The same MemoryLocation should
1349/// get clobbered by the same store (getModRefInfo does not use invariantness or
1350/// things like this, and if they start, we can modify MemoryLocOrCall to
1351/// include relevant data)
1352void MemorySSA::OptimizeUses::optimizeUsesInBlock(
  const BasicBlock *BB, unsigned long &StackEpoch, unsigned long &PopEpoch,
  SmallVectorImpl<MemoryAccess *> &VersionStack,
  DenseMap<MemoryLocOrCall, MemlocStackInfo> &LocStackInfo) {

/// If no accesses, nothing to do.
MemorySSA::AccessList *Accesses = MSSA->getWritableBlockAccesses(BB);
if (Accesses == nullptr)
  return;

// Pop everything that doesn't dominate the current block off the stack,
// increment the PopEpoch to account for this.
while (true) {
  assert(((!VersionStack.empty() && "Version stack should have liveOnEntry sentinel dominating everything"
) ? static_cast<void> (0) : __assert_fail ("!VersionStack.empty() && \"Version stack should have liveOnEntry sentinel dominating everything\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1367, __PRETTY_FUNCTION__))
      !VersionStack.empty() &&((!VersionStack.empty() && "Version stack should have liveOnEntry sentinel dominating everything"
) ? static_cast<void> (0) : __assert_fail ("!VersionStack.empty() && \"Version stack should have liveOnEntry sentinel dominating everything\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1367, __PRETTY_FUNCTION__))
      "Version stack should have liveOnEntry sentinel dominating everything")((!VersionStack.empty() && "Version stack should have liveOnEntry sentinel dominating everything"
) ? static_cast<void> (0) : __assert_fail ("!VersionStack.empty() && \"Version stack should have liveOnEntry sentinel dominating everything\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1367, __PRETTY_FUNCTION__));
  BasicBlock *BackBlock = VersionStack.back()->getBlock();
  if (DT->dominates(BackBlock, BB))
    break;
  while (VersionStack.back()->getBlock() == BackBlock)
    VersionStack.pop_back();
  ++PopEpoch;
}

for (MemoryAccess &MA : *Accesses) {
  auto *MU = dyn_cast<MemoryUse>(&MA);
  if (!MU) {
    VersionStack.push_back(&MA);
    ++StackEpoch;
    continue;
  }

  if (isUseTriviallyOptimizableToLiveOnEntry(*AA, MU->getMemoryInst())) {
    MU->setDefiningAccess(MSSA->getLiveOnEntryDef(), true, None);
    continue;
  }

  MemoryLocOrCall UseMLOC(MU);
  auto &LocInfo = LocStackInfo[UseMLOC];
  // If the pop epoch changed, it means we've removed stuff from top of
  // stack due to changing blocks. We may have to reset the lower bound or
  // last kill info.
  if (LocInfo.PopEpoch != PopEpoch) {
    LocInfo.PopEpoch = PopEpoch;
    LocInfo.StackEpoch = StackEpoch;
    // If the lower bound was in something that no longer dominates us, we
    // have to reset it.
    // We can't simply track stack size, because the stack may have had
    // pushes/pops in the meantime.
    // XXX: This is non-optimal, but only is slower cases with heavily
    // branching dominator trees.  To get the optimal number of queries would
    // be to make lowerbound and lastkill a per-loc stack, and pop it until
    // the top of that stack dominates us.  This does not seem worth it ATM.
    // A much cheaper optimization would be to always explore the deepest
    // branch of the dominator tree first. This will guarantee this resets on
    // the smallest set of blocks.
    if (LocInfo.LowerBoundBlock && LocInfo.LowerBoundBlock != BB &&
        !DT->dominates(LocInfo.LowerBoundBlock, BB)) {
      // Reset the lower bound of things to check.
      // TODO: Some day we should be able to reset to last kill, rather than
      // 0.
      LocInfo.LowerBound = 0;
      LocInfo.LowerBoundBlock = VersionStack[0]->getBlock();
      LocInfo.LastKillValid = false;
    }
  } else if (LocInfo.StackEpoch != StackEpoch) {
    // If all that has changed is the StackEpoch, we only have to check the
    // new things on the stack, because we've checked everything before.  In
    // this case, the lower bound of things to check remains the same.
    LocInfo.PopEpoch = PopEpoch;
    LocInfo.StackEpoch = StackEpoch;
  }
  if (!LocInfo.LastKillValid) {
    LocInfo.LastKill = VersionStack.size() - 1;
    LocInfo.LastKillValid = true;
    LocInfo.AR = MayAlias;
  }

  // At this point, we should have corrected last kill and LowerBound to be
  // in bounds.
  assert(LocInfo.LowerBound < VersionStack.size() &&((LocInfo.LowerBound < VersionStack.size() && "Lower bound out of range"
) ? static_cast<void> (0) : __assert_fail ("LocInfo.LowerBound < VersionStack.size() && \"Lower bound out of range\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1433, __PRETTY_FUNCTION__))
         "Lower bound out of range")((LocInfo.LowerBound < VersionStack.size() && "Lower bound out of range"
) ? static_cast<void> (0) : __assert_fail ("LocInfo.LowerBound < VersionStack.size() && \"Lower bound out of range\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1433, __PRETTY_FUNCTION__));
  assert(LocInfo.LastKill < VersionStack.size() &&((LocInfo.LastKill < VersionStack.size() && "Last kill info out of range"
) ? static_cast<void> (0) : __assert_fail ("LocInfo.LastKill < VersionStack.size() && \"Last kill info out of range\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1435, __PRETTY_FUNCTION__))
         "Last kill info out of range")((LocInfo.LastKill < VersionStack.size() && "Last kill info out of range"
) ? static_cast<void> (0) : __assert_fail ("LocInfo.LastKill < VersionStack.size() && \"Last kill info out of range\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1435, __PRETTY_FUNCTION__));
  // In any case, the new upper bound is the top of the stack.
  unsigned long UpperBound = VersionStack.size() - 1;

  if (UpperBound - LocInfo.LowerBound > MaxCheckLimit) {
    LLVM_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)
                      << *(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)
                      << " because there are "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)
                      << 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)
                      << " 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);
    // Because we did not walk, LastKill is no longer valid, as this may
    // have been a kill.
    LocInfo.LastKillValid = false;
    continue;
  }
  bool FoundClobberResult = false;
  unsigned UpwardWalkLimit = MaxCheckLimit;
  while (UpperBound > LocInfo.LowerBound) {
    if (isa<MemoryPhi>(VersionStack[UpperBound])) {
      // For phis, use the walker, see where we ended up, go there
      MemoryAccess *Result =
          Walker->getClobberingMemoryAccess(MU, UpwardWalkLimit);
      // We are guaranteed to find it or something is wrong
      while (VersionStack[UpperBound] != Result) {
        assert(UpperBound != 0)((UpperBound != 0) ? static_cast<void> (0) : __assert_fail
 ("UpperBound != 0", "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1459, __PRETTY_FUNCTION__));
        --UpperBound;
      }
      FoundClobberResult = true;
      break;
    }

    MemoryDef *MD = cast<MemoryDef>(VersionStack[UpperBound]);
    // If the lifetime of the pointer ends at this instruction, it's live on
    // entry.
    if (!UseMLOC.IsCall && lifetimeEndsAt(MD, UseMLOC.getLoc(), *AA)) {
      // Reset UpperBound to liveOnEntryDef's place in the stack
      UpperBound = 0;
      FoundClobberResult = true;
      LocInfo.AR = MustAlias;
      break;
    }
    ClobberAlias CA = instructionClobbersQuery(MD, MU, UseMLOC, *AA);
    if (CA.IsClobber) {
      FoundClobberResult = true;
      LocInfo.AR = CA.AR;
      break;
    }
    --UpperBound;
  }

  // Note: Phis always have AliasResult AR set to MayAlias ATM.

  // At the end of this loop, UpperBound is either a clobber, or lower bound
  // PHI walking may cause it to be < LowerBound, and in fact, < LastKill.
  if (FoundClobberResult || UpperBound < LocInfo.LastKill) {
    // We were last killed now by where we got to
    if (MSSA->isLiveOnEntryDef(VersionStack[UpperBound]))
      LocInfo.AR = None;
    MU->setDefiningAccess(VersionStack[UpperBound], true, LocInfo.AR);
    LocInfo.LastKill = UpperBound;
  } else {
    // Otherwise, we checked all the new ones, and now we know we can get to
    // LastKill.
    MU->setDefiningAccess(VersionStack[LocInfo.LastKill], true, LocInfo.AR);
  }
  LocInfo.LowerBound = VersionStack.size() - 1;
  LocInfo.LowerBoundBlock = BB;
}
1503}

1505/// Optimize uses to point to their actual clobbering definitions.
1506void MemorySSA::OptimizeUses::optimizeUses() {
SmallVector<MemoryAccess *, 16> VersionStack;
DenseMap<MemoryLocOrCall, MemlocStackInfo> LocStackInfo;
VersionStack.push_back(MSSA->getLiveOnEntryDef());

unsigned long StackEpoch = 1;
unsigned long PopEpoch = 1;
// We perform a non-recursive top-down dominator tree walk.
for (const auto *DomNode : depth_first(DT->getRootNode()))
  optimizeUsesInBlock(DomNode->getBlock(), StackEpoch, PopEpoch, VersionStack,
                      LocStackInfo);
1517}

1519void MemorySSA::placePHINodes(
  const SmallPtrSetImpl<BasicBlock *> &DefiningBlocks) {
// Determine where our MemoryPhi's should go
ForwardIDFCalculator IDFs(*DT);
IDFs.setDefiningBlocks(DefiningBlocks);
SmallVector<BasicBlock *, 32> IDFBlocks;
IDFs.calculate(IDFBlocks);

// Now place MemoryPhi nodes.
for (auto &BB : IDFBlocks)
  createMemoryPhi(BB);
1530}

1532void MemorySSA::buildMemorySSA(BatchAAResults &BAA) {
// We create an access to represent "live on entry", for things like
// arguments or users of globals, where the memory they use is defined before
// the beginning of the function. We do not actually insert it into the IR.
// We do not define a live on exit for the immediate uses, and thus our
// semantics do *not* imply that something with no immediate uses can simply
// be removed.
BasicBlock &StartingPoint = F.getEntryBlock();
LiveOnEntryDef.reset(new MemoryDef(F.getContext(), nullptr, nullptr,
                                   &StartingPoint, NextID++));

// We maintain lists of memory accesses per-block, trading memory for time. We
// could just look up the memory access for every possible instruction in the
// stream.
SmallPtrSet<BasicBlock *, 32> DefiningBlocks;
// Go through each block, figure out where defs occur, and chain together all
// the accesses.
for (BasicBlock &B : F) {
  bool InsertIntoDef = false;
  AccessList *Accesses = nullptr;
  DefsList *Defs = nullptr;
  for (Instruction &I : B) {
    MemoryUseOrDef *MUD = createNewAccess(&I, &BAA);
    if (!MUD)
      continue;

    if (!Accesses)
      Accesses = getOrCreateAccessList(&B);
    Accesses->push_back(MUD);
    if (isa<MemoryDef>(MUD)) {
      InsertIntoDef = true;
      if (!Defs)
        Defs = getOrCreateDefsList(&B);
      Defs->push_back(*MUD);
    }
  }
  if (InsertIntoDef)
    DefiningBlocks.insert(&B);
}
placePHINodes(DefiningBlocks);

// Now do regular SSA renaming on the MemoryDef/MemoryUse. Visited will get
// filled in with all blocks.
SmallPtrSet<BasicBlock *, 16> Visited;
renamePass(DT->getRootNode(), LiveOnEntryDef.get(), Visited);

ClobberWalkerBase<BatchAAResults> WalkerBase(this, &BAA, DT);
CachingWalker<BatchAAResults> WalkerLocal(this, &WalkerBase);
OptimizeUses(this, &WalkerLocal, &BAA, DT).optimizeUses();

// Mark the uses in unreachable blocks as live on entry, so that they go
// somewhere.
for (auto &BB : F)
  if (!Visited.count(&BB))
    markUnreachableAsLiveOnEntry(&BB);
1587}

1589MemorySSAWalker *MemorySSA::getWalker() { return getWalkerImpl(); }

1591MemorySSA::CachingWalker<AliasAnalysis> *MemorySSA::getWalkerImpl() {
if (Walker)
  return Walker.get();

if (!WalkerBase)
  WalkerBase =
      std::make_unique<ClobberWalkerBase<AliasAnalysis>>(this, AA, DT);

Walker =
    std::make_unique<CachingWalker<AliasAnalysis>>(this, WalkerBase.get());
return Walker.get();
1602}

1604MemorySSAWalker *MemorySSA::getSkipSelfWalker() {
if (SkipWalker)
  return SkipWalker.get();

if (!WalkerBase)
  WalkerBase =
      std::make_unique<ClobberWalkerBase<AliasAnalysis>>(this, AA, DT);

SkipWalker =
    std::make_unique<SkipSelfWalker<AliasAnalysis>>(this, WalkerBase.get());
return SkipWalker.get();
}


1618// This is a helper function used by the creation routines. It places NewAccess
1619// into the access and defs lists for a given basic block, at the given
1620// insertion point.
1621void MemorySSA::insertIntoListsForBlock(MemoryAccess *NewAccess,
                                      const BasicBlock *BB,
                                      InsertionPlace Point) {
auto *Accesses = getOrCreateAccessList(BB);
if (Point == Beginning) {
  // If it's a phi node, it goes first, otherwise, it goes after any phi
  // nodes.
  if (isa<MemoryPhi>(NewAccess)) {
    Accesses->push_front(NewAccess);
    auto *Defs = getOrCreateDefsList(BB);
    Defs->push_front(*NewAccess);
  } else {
    auto AI = find_if_not(
        *Accesses, [](const MemoryAccess &MA) { return isa<MemoryPhi>(MA); });
    Accesses->insert(AI, NewAccess);
    if (!isa<MemoryUse>(NewAccess)) {
      auto *Defs = getOrCreateDefsList(BB);
      auto DI = find_if_not(
          *Defs, [](const MemoryAccess &MA) { return isa<MemoryPhi>(MA); });
      Defs->insert(DI, *NewAccess);
    }
  }
} else {
  Accesses->push_back(NewAccess);
  if (!isa<MemoryUse>(NewAccess)) {
    auto *Defs = getOrCreateDefsList(BB);
    Defs->push_back(*NewAccess);
  }
}
BlockNumberingValid.erase(BB);
1651}

1653void MemorySSA::insertIntoListsBefore(MemoryAccess *What, const BasicBlock *BB,
                                    AccessList::iterator InsertPt) {
auto *Accesses = getWritableBlockAccesses(BB);
bool WasEnd = InsertPt == Accesses->end();
Accesses->insert(AccessList::iterator(InsertPt), What);
if (!isa<MemoryUse>(What)) {
  auto *Defs = getOrCreateDefsList(BB);
  // If we got asked to insert at the end, we have an easy job, just shove it
  // at the end. If we got asked to insert before an existing def, we also get
  // an iterator. If we got asked to insert before a use, we have to hunt for
  // the next def.
  if (WasEnd) {
    Defs->push_back(*What);
  } else if (isa<MemoryDef>(InsertPt)) {
    Defs->insert(InsertPt->getDefsIterator(), *What);
  } else {
    while (InsertPt != Accesses->end() && !isa<MemoryDef>(InsertPt))
      ++InsertPt;
    // Either we found a def, or we are inserting at the end
    if (InsertPt == Accesses->end())
      Defs->push_back(*What);
    else
      Defs->insert(InsertPt->getDefsIterator(), *What);
  }
}
BlockNumberingValid.erase(BB);
1679}

1681void MemorySSA::prepareForMoveTo(MemoryAccess *What, BasicBlock *BB) {
// Keep it in the lookup tables, remove from the lists
removeFromLists(What, false);

// Note that moving should implicitly invalidate the optimized state of a
// MemoryUse (and Phis can't be optimized). However, it doesn't do so for a
// MemoryDef.
if (auto *MD = dyn_cast<MemoryDef>(What))
  MD->resetOptimized();
What->setBlock(BB);
1691}

1693// Move What before Where in the IR.  The end result is that What will belong to
1694// the right lists and have the right Block set, but will not otherwise be
1695// correct. It will not have the right defining access, and if it is a def,
1696// things below it will not properly be updated.
1697void MemorySSA::moveTo(MemoryUseOrDef *What, BasicBlock *BB,
                     AccessList::iterator Where) {
prepareForMoveTo(What, BB);
insertIntoListsBefore(What, BB, Where);
1701}

1703void MemorySSA::moveTo(MemoryAccess *What, BasicBlock *BB,
                     InsertionPlace Point) {
if (isa<MemoryPhi>(What)) {
  assert(Point == Beginning &&((Point == Beginning && "Can only move a Phi at the beginning of the block"
) ? static_cast<void> (0) : __assert_fail ("Point == Beginning && \"Can only move a Phi at the beginning of the block\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1707, __PRETTY_FUNCTION__))
         "Can only move a Phi at the beginning of the block")((Point == Beginning && "Can only move a Phi at the beginning of the block"
) ? static_cast<void> (0) : __assert_fail ("Point == Beginning && \"Can only move a Phi at the beginning of the block\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1707, __PRETTY_FUNCTION__));
  // Update lookup table entry
  ValueToMemoryAccess.erase(What->getBlock());
  bool Inserted = ValueToMemoryAccess.insert({BB, What}).second;
  (void)Inserted;
  assert(Inserted && "Cannot move a Phi to a block that already has one")((Inserted && "Cannot move a Phi to a block that already has one"
) ? static_cast<void> (0) : __assert_fail ("Inserted && \"Cannot move a Phi to a block that already has one\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1712, __PRETTY_FUNCTION__));
}

prepareForMoveTo(What, BB);
insertIntoListsForBlock(What, BB, Point);
1717}

1719MemoryPhi *MemorySSA::createMemoryPhi(BasicBlock *BB) {
assert(!getMemoryAccess(BB) && "MemoryPhi already exists for this BB")((!getMemoryAccess(BB) && "MemoryPhi already exists for this BB"
) ? static_cast<void> (0) : __assert_fail ("!getMemoryAccess(BB) && \"MemoryPhi already exists for this BB\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1720, __PRETTY_FUNCTION__));
MemoryPhi *Phi = new MemoryPhi(BB->getContext(), BB, NextID++);
// Phi's always are placed at the front of the block.
insertIntoListsForBlock(Phi, BB, Beginning);
ValueToMemoryAccess[BB] = Phi;
return Phi;
1726}

1728MemoryUseOrDef *MemorySSA::createDefinedAccess(Instruction *I,
                                             MemoryAccess *Definition,
                                             const MemoryUseOrDef *Template,
                                             bool CreationMustSucceed) {
assert(!isa<PHINode>(I) && "Cannot create a defined access for a PHI")((!isa<PHINode>(I) && "Cannot create a defined access for a PHI"
) ? static_cast<void> (0) : __assert_fail ("!isa<PHINode>(I) && \"Cannot create a defined access for a PHI\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1732, __PRETTY_FUNCTION__));
MemoryUseOrDef *NewAccess = createNewAccess(I, AA, Template);
if (CreationMustSucceed)
  assert(NewAccess != nullptr && "Tried to create a memory access for a "((NewAccess != nullptr && "Tried to create a memory access for a "
 "non-memory touching instruction") ? static_cast<void>
 (0) : __assert_fail ("NewAccess != nullptr && \"Tried to create a memory access for a \" \"non-memory touching instruction\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1736, __PRETTY_FUNCTION__))
                                 "non-memory touching instruction")((NewAccess != nullptr && "Tried to create a memory access for a "
 "non-memory touching instruction") ? static_cast<void>
 (0) : __assert_fail ("NewAccess != nullptr && \"Tried to create a memory access for a \" \"non-memory touching instruction\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1736, __PRETTY_FUNCTION__));
if (NewAccess) {
  assert((!Definition || !isa<MemoryUse>(Definition)) &&(((!Definition || !isa<MemoryUse>(Definition)) &&
 "A use cannot be a defining access") ? static_cast<void>
 (0) : __assert_fail ("(!Definition || !isa<MemoryUse>(Definition)) && \"A use cannot be a defining access\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1739, __PRETTY_FUNCTION__))
         "A use cannot be a defining access")(((!Definition || !isa<MemoryUse>(Definition)) &&
 "A use cannot be a defining access") ? static_cast<void>
 (0) : __assert_fail ("(!Definition || !isa<MemoryUse>(Definition)) && \"A use cannot be a defining access\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1739, __PRETTY_FUNCTION__));
  NewAccess->setDefiningAccess(Definition);
}
return NewAccess;
1743}

1745// Return true if the instruction has ordering constraints.
1746// Note specifically that this only considers stores and loads
1747// because others are still considered ModRef by getModRefInfo.
1748static inline bool isOrdered(const Instruction *I) {
if (auto *SI = dyn_cast<StoreInst>(I)) {
  if (!SI->isUnordered())
    return true;
} else if (auto *LI = dyn_cast<LoadInst>(I)) {
  if (!LI->isUnordered())
    return true;
}
return false;
1757}

1759/// Helper function to create new memory accesses
1760template <typename AliasAnalysisType>
1761MemoryUseOrDef *MemorySSA::createNewAccess(Instruction *I,
                                         AliasAnalysisType *AAP,
                                         const MemoryUseOrDef *Template) {
// The assume intrinsic has a control dependency which we model by claiming
// that it writes arbitrarily. Debuginfo intrinsics may be considered
// clobbers when we have a nonstandard AA pipeline. Ignore these fake memory
// dependencies here.
// FIXME: Replace this special casing with a more accurate modelling of
// assume's control dependency.
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I))
  if (II->getIntrinsicID() == Intrinsic::assume)
    return nullptr;

// Using a nonstandard AA pipelines might leave us with unexpected modref
// results for I, so add a check to not model instructions that may not read
// from or write to memory. This is necessary for correctness.
if (!I->mayReadFromMemory() && !I->mayWriteToMemory())
  return nullptr;

bool Def, Use;
if (Template) {
  Def = dyn_cast_or_null<MemoryDef>(Template) != nullptr;
  Use = dyn_cast_or_null<MemoryUse>(Template) != nullptr;
1784#if !defined(NDEBUG)
  ModRefInfo ModRef = AAP->getModRefInfo(I, None);
  bool DefCheck, UseCheck;
  DefCheck = isModSet(ModRef) || isOrdered(I);
  UseCheck = isRefSet(ModRef);
  assert(Def == DefCheck && (Def || Use == UseCheck) && "Invalid template")((Def == DefCheck && (Def || Use == UseCheck) &&
 "Invalid template") ? static_cast<void> (0) : __assert_fail
 ("Def == DefCheck && (Def || Use == UseCheck) && \"Invalid template\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1789, __PRETTY_FUNCTION__));
1790#endif
} else {
  // Find out what affect this instruction has on memory.
  ModRefInfo ModRef = AAP->getModRefInfo(I, None);
  // The isOrdered check is used to ensure that volatiles end up as defs
  // (atomics end up as ModRef right now anyway).  Until we separate the
  // ordering chain from the memory chain, this enables people to see at least
  // some relative ordering to volatiles.  Note that getClobberingMemoryAccess
  // will still give an answer that bypasses other volatile loads.  TODO:
  // Separate memory aliasing and ordering into two different chains so that
  // we can precisely represent both "what memory will this read/write/is
  // clobbered by" and "what instructions can I move this past".
  Def = isModSet(ModRef) || isOrdered(I);
  Use = isRefSet(ModRef);
}

// It's possible for an instruction to not modify memory at all. During
// construction, we ignore them.
if (!Def && !Use)
  return nullptr;

MemoryUseOrDef *MUD;
if (Def)
  MUD = new MemoryDef(I->getContext(), nullptr, I, I->getParent(), NextID++);
else
  MUD = new MemoryUse(I->getContext(), nullptr, I, I->getParent());
ValueToMemoryAccess[I] = MUD;
return MUD;
1818}

1820/// Returns true if \p Replacer dominates \p Replacee .
1821bool MemorySSA::dominatesUse(const MemoryAccess *Replacer,
                           const MemoryAccess *Replacee) const {
if (isa<MemoryUseOrDef>(Replacee))
  return DT->dominates(Replacer->getBlock(), Replacee->getBlock());
const auto *MP = cast<MemoryPhi>(Replacee);
// For a phi node, the use occurs in the predecessor block of the phi node.
// Since we may occur multiple times in the phi node, we have to check each
// operand to ensure Replacer dominates each operand where Replacee occurs.
for (const Use &Arg : MP->operands()) {
  if (Arg.get() != Replacee &&
      !DT->dominates(Replacer->getBlock(), MP->getIncomingBlock(Arg)))
    return false;
}
return true;
1835}

1837/// Properly remove \p MA from all of MemorySSA's lookup tables.
1838void MemorySSA::removeFromLookups(MemoryAccess *MA) {
assert(MA->use_empty() &&((MA->use_empty() && "Trying to remove memory access that still has uses"
) ? static_cast<void> (0) : __assert_fail ("MA->use_empty() && \"Trying to remove memory access that still has uses\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1840, __PRETTY_FUNCTION__))
       "Trying to remove memory access that still has uses")((MA->use_empty() && "Trying to remove memory access that still has uses"
) ? static_cast<void> (0) : __assert_fail ("MA->use_empty() && \"Trying to remove memory access that still has uses\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1840, __PRETTY_FUNCTION__));
BlockNumbering.erase(MA);
if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
  MUD->setDefiningAccess(nullptr);
// Invalidate our walker's cache if necessary
if (!isa<MemoryUse>(MA))
  getWalker()->invalidateInfo(MA);

Value *MemoryInst;
if (const auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
  MemoryInst = MUD->getMemoryInst();
else
  MemoryInst = MA->getBlock();

auto VMA = ValueToMemoryAccess.find(MemoryInst);
if (VMA->second == MA)
  ValueToMemoryAccess.erase(VMA);
1857}

1859/// Properly remove \p MA from all of MemorySSA's lists.
1860///
1861/// Because of the way the intrusive list and use lists work, it is important to
1862/// do removal in the right order.
1863/// ShouldDelete defaults to true, and will cause the memory access to also be
1864/// deleted, not just removed.
1865void MemorySSA::removeFromLists(MemoryAccess *MA, bool ShouldDelete) {
BasicBlock *BB = MA->getBlock();
// The access list owns the reference, so we erase it from the non-owning list
// first.
if (!isa<MemoryUse>(MA)) {
  auto DefsIt = PerBlockDefs.find(BB);
  std::unique_ptr<DefsList> &Defs = DefsIt->second;
  Defs->remove(*MA);
  if (Defs->empty())
    PerBlockDefs.erase(DefsIt);
}

// The erase call here will delete it. If we don't want it deleted, we call
// remove instead.
auto AccessIt = PerBlockAccesses.find(BB);
std::unique_ptr<AccessList> &Accesses = AccessIt->second;
if (ShouldDelete)
  Accesses->erase(MA);
else
  Accesses->remove(MA);

if (Accesses->empty()) {
  PerBlockAccesses.erase(AccessIt);
  BlockNumberingValid.erase(BB);
}
1890}

1892void MemorySSA::print(raw_ostream &OS) const {
MemorySSAAnnotatedWriter Writer(this);
F.print(OS, &Writer);
1895}

1897#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1898LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void MemorySSA::dump() const { print(dbgs()); }
1899#endif

1901void MemorySSA::verifyMemorySSA() const {
verifyOrderingDominationAndDefUses(F);
4
←
Calling 'MemorySSA::verifyOrderingDominationAndDefUses'→
verifyDominationNumbers(F);
verifyPrevDefInPhis(F);
// Previously, the verification used to also verify that the clobberingAccess
// cached by MemorySSA is the same as the clobberingAccess found at a later
// query to AA. This does not hold true in general due to the current fragility
// of BasicAA which has arbitrary caps on the things it analyzes before giving
// up. As a result, transformations that are correct, will lead to BasicAA
// returning different Alias answers before and after that transformation.
// Invalidating MemorySSA is not an option, as the results in BasicAA can be so
// random, in the worst case we'd need to rebuild MemorySSA from scratch after
// every transformation, which defeats the purpose of using it. For such an
// example, see test4 added in D51960.
1915}

1917void MemorySSA::verifyPrevDefInPhis(Function &F) const {
1918#if !defined(NDEBUG) && defined(EXPENSIVE_CHECKS)
for (const BasicBlock &BB : F) {
  if (MemoryPhi *Phi = getMemoryAccess(&BB)) {
    for (unsigned I = 0, E = Phi->getNumIncomingValues(); I != E; ++I) {
      auto *Pred = Phi->getIncomingBlock(I);
      auto *IncAcc = Phi->getIncomingValue(I);
      // If Pred has no unreachable predecessors, get last def looking at
      // IDoms. If, while walkings IDoms, any of these has an unreachable
      // predecessor, then the incoming def can be any access.
      if (auto *DTNode = DT->getNode(Pred)) {
        while (DTNode) {
          if (auto *DefList = getBlockDefs(DTNode->getBlock())) {
            auto *LastAcc = &*(--DefList->end());
            assert(LastAcc == IncAcc &&((LastAcc == IncAcc && "Incorrect incoming access into phi."
) ? static_cast<void> (0) : __assert_fail ("LastAcc == IncAcc && \"Incorrect incoming access into phi.\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1932, __PRETTY_FUNCTION__))
                   "Incorrect incoming access into phi.")((LastAcc == IncAcc && "Incorrect incoming access into phi."
) ? static_cast<void> (0) : __assert_fail ("LastAcc == IncAcc && \"Incorrect incoming access into phi.\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1932, __PRETTY_FUNCTION__));
            break;
          }
          DTNode = DTNode->getIDom();
        }
      } else {
        // If Pred has unreachable predecessors, but has at least a Def, the
        // incoming access can be the last Def in Pred, or it could have been
        // optimized to LoE. After an update, though, the LoE may have been
        // replaced by another access, so IncAcc may be any access.
        // If Pred has unreachable predecessors and no Defs, incoming access
        // should be LoE; However, after an update, it may be any access.
      }
    }
  }
}
1948#endif
1949}

1951/// Verify that all of the blocks we believe to have valid domination numbers
1952/// actually have valid domination numbers.
1953void MemorySSA::verifyDominationNumbers(const Function &F) const {
1954#ifndef NDEBUG
if (BlockNumberingValid.empty())
  return;

SmallPtrSet<const BasicBlock *, 16> ValidBlocks = BlockNumberingValid;
for (const BasicBlock &BB : F) {
  if (!ValidBlocks.count(&BB))
    continue;

  ValidBlocks.erase(&BB);

  const AccessList *Accesses = getBlockAccesses(&BB);
  // It's correct to say an empty block has valid numbering.
  if (!Accesses)
    continue;

  // Block numbering starts at 1.
  unsigned long LastNumber = 0;
  for (const MemoryAccess &MA : *Accesses) {
    auto ThisNumberIter = BlockNumbering.find(&MA);
    assert(ThisNumberIter != BlockNumbering.end() &&((ThisNumberIter != BlockNumbering.end() && "MemoryAccess has no domination number in a valid block!"
) ? static_cast<void> (0) : __assert_fail ("ThisNumberIter != BlockNumbering.end() && \"MemoryAccess has no domination number in a valid block!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1975, __PRETTY_FUNCTION__))
           "MemoryAccess has no domination number in a valid block!")((ThisNumberIter != BlockNumbering.end() && "MemoryAccess has no domination number in a valid block!"
) ? static_cast<void> (0) : __assert_fail ("ThisNumberIter != BlockNumbering.end() && \"MemoryAccess has no domination number in a valid block!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1975, __PRETTY_FUNCTION__));

    unsigned long ThisNumber = ThisNumberIter->second;
    assert(ThisNumber > LastNumber &&((ThisNumber > LastNumber && "Domination numbers should be strictly increasing!"
) ? static_cast<void> (0) : __assert_fail ("ThisNumber > LastNumber && \"Domination numbers should be strictly increasing!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1979, __PRETTY_FUNCTION__))
           "Domination numbers should be strictly increasing!")((ThisNumber > LastNumber && "Domination numbers should be strictly increasing!"
) ? static_cast<void> (0) : __assert_fail ("ThisNumber > LastNumber && \"Domination numbers should be strictly increasing!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1979, __PRETTY_FUNCTION__));
    LastNumber = ThisNumber;
  }
}

assert(ValidBlocks.empty() &&((ValidBlocks.empty() && "All valid BasicBlocks should exist in F -- dangling pointers?"
) ? static_cast<void> (0) : __assert_fail ("ValidBlocks.empty() && \"All valid BasicBlocks should exist in F -- dangling pointers?\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1985, __PRETTY_FUNCTION__))
       "All valid BasicBlocks should exist in F -- dangling pointers?")((ValidBlocks.empty() && "All valid BasicBlocks should exist in F -- dangling pointers?"
) ? static_cast<void> (0) : __assert_fail ("ValidBlocks.empty() && \"All valid BasicBlocks should exist in F -- dangling pointers?\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 1985, __PRETTY_FUNCTION__));
1986#endif
1987}

1989/// Verify ordering: the order and existence of MemoryAccesses matches the
1990/// order and existence of memory affecting instructions.
1991/// Verify domination: each definition dominates all of its uses.
1992/// Verify def-uses: the immediate use information - walk all the memory
1993/// accesses and verifying that, for each use, it appears in the appropriate
1994/// def's use list
1995void MemorySSA::verifyOrderingDominationAndDefUses(Function &F) const {
1996#if !defined(NDEBUG)
// Walk all the blocks, comparing what the lookups think and what the access
// lists think, as well as the order in the blocks vs the order in the access
// lists.
SmallVector<MemoryAccess *, 32> ActualAccesses;
SmallVector<MemoryAccess *, 32> ActualDefs;
for (BasicBlock &B : F) {
  const AccessList *AL = getBlockAccesses(&B);
5
←
Calling 'MemorySSA::getBlockAccesses'→
14
←
Returning from 'MemorySSA::getBlockAccesses'→
15
←
'AL' initialized here→
  const auto *DL = getBlockDefs(&B);
16
←
Calling 'MemorySSA::getBlockDefs'→
23
←
Returning from 'MemorySSA::getBlockDefs'→
  MemoryPhi *Phi = getMemoryAccess(&B);
24
←
Calling 'MemorySSA::getMemoryAccess'→
28
←
Returning from 'MemorySSA::getMemoryAccess'→
  if (Phi28.1
'Phi' is null
1
'Phi' is null
) {
29
←
Taking false branch→
    // Verify ordering.
    ActualAccesses.push_back(Phi);
    ActualDefs.push_back(Phi);
    // Verify domination
    for (const Use &U : Phi->uses())
      assert(dominates(Phi, U) && "Memory PHI does not dominate it's uses")((dominates(Phi, U) && "Memory PHI does not dominate it's uses"
) ? static_cast<void> (0) : __assert_fail ("dominates(Phi, U) && \"Memory PHI does not dominate it's uses\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2012, __PRETTY_FUNCTION__));
2013#if defined(EXPENSIVE_CHECKS)
    // Verify def-uses.
    assert(Phi->getNumOperands() == static_cast<unsigned>(std::distance(((Phi->getNumOperands() == static_cast<unsigned>(std
::distance( pred_begin(&B), pred_end(&B))) &&
 "Incomplete MemoryPhi Node") ? static_cast<void> (0) :
 __assert_fail ("Phi->getNumOperands() == static_cast<unsigned>(std::distance( pred_begin(&B), pred_end(&B))) && \"Incomplete MemoryPhi Node\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2017, __PRETTY_FUNCTION__))
                                        pred_begin(&B), pred_end(&B))) &&((Phi->getNumOperands() == static_cast<unsigned>(std
::distance( pred_begin(&B), pred_end(&B))) &&
 "Incomplete MemoryPhi Node") ? static_cast<void> (0) :
 __assert_fail ("Phi->getNumOperands() == static_cast<unsigned>(std::distance( pred_begin(&B), pred_end(&B))) && \"Incomplete MemoryPhi Node\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2017, __PRETTY_FUNCTION__))
           "Incomplete MemoryPhi Node")((Phi->getNumOperands() == static_cast<unsigned>(std
::distance( pred_begin(&B), pred_end(&B))) &&
 "Incomplete MemoryPhi Node") ? static_cast<void> (0) :
 __assert_fail ("Phi->getNumOperands() == static_cast<unsigned>(std::distance( pred_begin(&B), pred_end(&B))) && \"Incomplete MemoryPhi Node\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2017, __PRETTY_FUNCTION__));
    for (unsigned I = 0, E = Phi->getNumIncomingValues(); I != E; ++I) {
      verifyUseInDefs(Phi->getIncomingValue(I), Phi);
      assert(find(predecessors(&B), Phi->getIncomingBlock(I)) !=((find(predecessors(&B), Phi->getIncomingBlock(I)) != pred_end
(&B) && "Incoming phi block not a block predecessor"
) ? static_cast<void> (0) : __assert_fail ("find(predecessors(&B), Phi->getIncomingBlock(I)) != pred_end(&B) && \"Incoming phi block not a block predecessor\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2022, __PRETTY_FUNCTION__))
                 pred_end(&B) &&((find(predecessors(&B), Phi->getIncomingBlock(I)) != pred_end
(&B) && "Incoming phi block not a block predecessor"
) ? static_cast<void> (0) : __assert_fail ("find(predecessors(&B), Phi->getIncomingBlock(I)) != pred_end(&B) && \"Incoming phi block not a block predecessor\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2022, __PRETTY_FUNCTION__))
             "Incoming phi block not a block predecessor")((find(predecessors(&B), Phi->getIncomingBlock(I)) != pred_end
(&B) && "Incoming phi block not a block predecessor"
) ? static_cast<void> (0) : __assert_fail ("find(predecessors(&B), Phi->getIncomingBlock(I)) != pred_end(&B) && \"Incoming phi block not a block predecessor\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2022, __PRETTY_FUNCTION__));
    }
2024#endif
  }

  for (Instruction &I : B) {
    MemoryUseOrDef *MA = getMemoryAccess(&I);
    assert((!MA || (AL && (isa<MemoryUse>(MA) || DL))) &&(((!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") ? static_cast<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-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2032, __PRETTY_FUNCTION__))
           "We have memory affecting instructions "(((!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") ? static_cast<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-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2032, __PRETTY_FUNCTION__))
           "in this block but they are not in the "(((!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") ? static_cast<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-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2032, __PRETTY_FUNCTION__))
           "access list or defs list")(((!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") ? static_cast<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-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2032, __PRETTY_FUNCTION__));
    if (MA) {
      // Verify ordering.
      ActualAccesses.push_back(MA);
      if (MemoryAccess *MD = dyn_cast<MemoryDef>(MA)) {
        // Verify ordering.
        ActualDefs.push_back(MA);
        // Verify domination.
        for (const Use &U : MD->uses())
          assert(dominates(MD, U) &&((dominates(MD, U) && "Memory Def does not dominate it's uses"
) ? static_cast<void> (0) : __assert_fail ("dominates(MD, U) && \"Memory Def does not dominate it's uses\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2042, __PRETTY_FUNCTION__))
                 "Memory Def does not dominate it's uses")((dominates(MD, U) && "Memory Def does not dominate it's uses"
) ? static_cast<void> (0) : __assert_fail ("dominates(MD, U) && \"Memory Def does not dominate it's uses\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2042, __PRETTY_FUNCTION__));
      }
2044#if defined(EXPENSIVE_CHECKS)
      // Verify def-uses.
      verifyUseInDefs(MA->getDefiningAccess(), MA);
2047#endif
    }
  }
  // Either we hit the assert, really have no accesses, or we have both
  // accesses and an access list. Same with defs.
  if (!AL && !DL)
30
←
Assuming 'AL' is null→
31
←
Assuming pointer value is null→
32
←
Assuming 'DL' is non-null→
33
←
Taking false branch→
    continue;
  // Verify ordering.
  assert(AL->size() == ActualAccesses.size() &&((AL->size() == ActualAccesses.size() && "We don't have the same number of accesses in the block as on the "
 "access list") ? static_cast<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-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2057, __PRETTY_FUNCTION__))
34
←
Called C++ object pointer is null
         "We don't have the same number of accesses in the block as on the "((AL->size() == ActualAccesses.size() && "We don't have the same number of accesses in the block as on the "
 "access list") ? static_cast<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-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2057, __PRETTY_FUNCTION__))
         "access list")((AL->size() == ActualAccesses.size() && "We don't have the same number of accesses in the block as on the "
 "access list") ? static_cast<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-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2057, __PRETTY_FUNCTION__));
  assert((DL || ActualDefs.size() == 0) &&(((DL || ActualDefs.size() == 0) && "Either we should have a defs list, or we should have no defs"
) ? static_cast<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-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2059, __PRETTY_FUNCTION__))
         "Either we should have a defs list, or we should have no defs")(((DL || ActualDefs.size() == 0) && "Either we should have a defs list, or we should have no defs"
) ? static_cast<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-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2059, __PRETTY_FUNCTION__));
  assert((!DL || DL->size() == ActualDefs.size()) &&(((!DL || DL->size() == ActualDefs.size()) && "We don't have the same number of defs in the block as on the "
 "def list") ? static_cast<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-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2062, __PRETTY_FUNCTION__))
         "We don't have the same number of defs in the block as on the "(((!DL || DL->size() == ActualDefs.size()) && "We don't have the same number of defs in the block as on the "
 "def list") ? static_cast<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-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2062, __PRETTY_FUNCTION__))
         "def list")(((!DL || DL->size() == ActualDefs.size()) && "We don't have the same number of defs in the block as on the "
 "def list") ? static_cast<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-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2062, __PRETTY_FUNCTION__));
  auto ALI = AL->begin();
  auto AAI = ActualAccesses.begin();
  while (ALI != AL->end() && AAI != ActualAccesses.end()) {
    assert(&*ALI == *AAI && "Not the same accesses in the same order")((&*ALI == *AAI && "Not the same accesses in the same order"
) ? static_cast<void> (0) : __assert_fail ("&*ALI == *AAI && \"Not the same accesses in the same order\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2066, __PRETTY_FUNCTION__));
    ++ALI;
    ++AAI;
  }
  ActualAccesses.clear();
  if (DL) {
    auto DLI = DL->begin();
    auto ADI = ActualDefs.begin();
    while (DLI != DL->end() && ADI != ActualDefs.end()) {
      assert(&*DLI == *ADI && "Not the same defs in the same order")((&*DLI == *ADI && "Not the same defs in the same order"
) ? static_cast<void> (0) : __assert_fail ("&*DLI == *ADI && \"Not the same defs in the same order\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2075, __PRETTY_FUNCTION__));
      ++DLI;
      ++ADI;
    }
  }
  ActualDefs.clear();
}
2082#endif
2083}

2085/// Verify the def-use lists in MemorySSA, by verifying that \p Use
2086/// appears in the use list of \p Def.
2087void MemorySSA::verifyUseInDefs(MemoryAccess *Def, MemoryAccess *Use) const {
2088#ifndef NDEBUG
// The live on entry use may cause us to get a NULL def here
if (!Def)
  assert(isLiveOnEntryDef(Use) &&((isLiveOnEntryDef(Use) && "Null def but use not point to live on entry def"
) ? static_cast<void> (0) : __assert_fail ("isLiveOnEntryDef(Use) && \"Null def but use not point to live on entry def\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2092, __PRETTY_FUNCTION__))
         "Null def but use not point to live on entry def")((isLiveOnEntryDef(Use) && "Null def but use not point to live on entry def"
) ? static_cast<void> (0) : __assert_fail ("isLiveOnEntryDef(Use) && \"Null def but use not point to live on entry def\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2092, __PRETTY_FUNCTION__));
else
  assert(is_contained(Def->users(), Use) &&((is_contained(Def->users(), Use) && "Did not find use in def's use list"
) ? static_cast<void> (0) : __assert_fail ("is_contained(Def->users(), Use) && \"Did not find use in def's use list\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2095, __PRETTY_FUNCTION__))
         "Did not find use in def's use list")((is_contained(Def->users(), Use) && "Did not find use in def's use list"
) ? static_cast<void> (0) : __assert_fail ("is_contained(Def->users(), Use) && \"Did not find use in def's use list\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2095, __PRETTY_FUNCTION__));
2096#endif
2097}

2099/// Perform a local numbering on blocks so that instruction ordering can be
2100/// determined in constant time.
2101/// TODO: We currently just number in order.  If we numbered by N, we could
2102/// allow at least N-1 sequences of insertBefore or insertAfter (and at least
2103/// log2(N) sequences of mixed before and after) without needing to invalidate
2104/// the numbering.
2105void MemorySSA::renumberBlock(const BasicBlock *B) const {
// The pre-increment ensures the numbers really start at 1.
unsigned long CurrentNumber = 0;
const AccessList *AL = getBlockAccesses(B);
assert(AL != nullptr && "Asking to renumber an empty block")((AL != nullptr && "Asking to renumber an empty block"
) ? static_cast<void> (0) : __assert_fail ("AL != nullptr && \"Asking to renumber an empty block\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2109, __PRETTY_FUNCTION__));
for (const auto &I : *AL)
  BlockNumbering[&I] = ++CurrentNumber;
BlockNumberingValid.insert(B);
2113}

2115/// Determine, for two memory accesses in the same block,
2116/// whether \p Dominator dominates \p Dominatee.
2117/// \returns True if \p Dominator dominates \p Dominatee.
2118bool MemorySSA::locallyDominates(const MemoryAccess *Dominator,
                               const MemoryAccess *Dominatee) const {
const BasicBlock *DominatorBlock = Dominator->getBlock();

assert((DominatorBlock == Dominatee->getBlock()) &&(((DominatorBlock == Dominatee->getBlock()) && "Asking for local domination when accesses are in different blocks!"
) ? static_cast<void> (0) : __assert_fail ("(DominatorBlock == Dominatee->getBlock()) && \"Asking for local domination when accesses are in different blocks!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2123, __PRETTY_FUNCTION__))
       "Asking for local domination when accesses are in different blocks!")(((DominatorBlock == Dominatee->getBlock()) && "Asking for local domination when accesses are in different blocks!"
) ? static_cast<void> (0) : __assert_fail ("(DominatorBlock == Dominatee->getBlock()) && \"Asking for local domination when accesses are in different blocks!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2123, __PRETTY_FUNCTION__));
// A node dominates itself.
if (Dominatee == Dominator)
  return true;

// When Dominatee is defined on function entry, it is not dominated by another
// memory access.
if (isLiveOnEntryDef(Dominatee))
  return false;

// When Dominator is defined on function entry, it dominates the other memory
// access.
if (isLiveOnEntryDef(Dominator))
  return true;

if (!BlockNumberingValid.count(DominatorBlock))
  renumberBlock(DominatorBlock);

unsigned long DominatorNum = BlockNumbering.lookup(Dominator);
// All numbers start with 1
assert(DominatorNum != 0 && "Block was not numbered properly")((DominatorNum != 0 && "Block was not numbered properly"
) ? static_cast<void> (0) : __assert_fail ("DominatorNum != 0 && \"Block was not numbered properly\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2143, __PRETTY_FUNCTION__));
unsigned long DominateeNum = BlockNumbering.lookup(Dominatee);
assert(DominateeNum != 0 && "Block was not numbered properly")((DominateeNum != 0 && "Block was not numbered properly"
) ? static_cast<void> (0) : __assert_fail ("DominateeNum != 0 && \"Block was not numbered properly\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2145, __PRETTY_FUNCTION__));
return DominatorNum < DominateeNum;
2147}

2149bool MemorySSA::dominates(const MemoryAccess *Dominator,
                        const MemoryAccess *Dominatee) const {
if (Dominator == Dominatee)
  return true;

if (isLiveOnEntryDef(Dominatee))
  return false;

if (Dominator->getBlock() != Dominatee->getBlock())
  return DT->dominates(Dominator->getBlock(), Dominatee->getBlock());
return locallyDominates(Dominator, Dominatee);
2160}

2162bool MemorySSA::dominates(const MemoryAccess *Dominator,
                        const Use &Dominatee) const {
if (MemoryPhi *MP = dyn_cast<MemoryPhi>(Dominatee.getUser())) {
  BasicBlock *UseBB = MP->getIncomingBlock(Dominatee);
  // The def must dominate the incoming block of the phi.
  if (UseBB != Dominator->getBlock())
    return DT->dominates(Dominator->getBlock(), UseBB);
  // If the UseBB and the DefBB are the same, compare locally.
  return locallyDominates(Dominator, cast<MemoryAccess>(Dominatee));
}
// If it's not a PHI node use, the normal dominates can already handle it.
return dominates(Dominator, cast<MemoryAccess>(Dominatee.getUser()));
2174}

2176const static char LiveOnEntryStr[] = "liveOnEntry";

2178void MemoryAccess::print(raw_ostream &OS) const {
switch (getValueID()) {
case MemoryPhiVal: return static_cast<const MemoryPhi *>(this)->print(OS);
case MemoryDefVal: return static_cast<const MemoryDef *>(this)->print(OS);
case MemoryUseVal: return static_cast<const MemoryUse *>(this)->print(OS);
}
llvm_unreachable("invalid value id")::llvm::llvm_unreachable_internal("invalid value id", "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2184);
2185}

2187void MemoryDef::print(raw_ostream &OS) const {
MemoryAccess *UO = getDefiningAccess();

auto printID = [&OS](MemoryAccess *A) {
  if (A && A->getID())
    OS << A->getID();
  else
    OS << LiveOnEntryStr;
};

OS << getID() << " = MemoryDef(";
printID(UO);
OS << ")";

if (isOptimized()) {
  OS << "->";
  printID(getOptimized());

  if (Optional<AliasResult> AR = getOptimizedAccessType())
    OS << " " << *AR;
}
2208}

2210void MemoryPhi::print(raw_ostream &OS) const {
bool First = true;
OS << getID() << " = MemoryPhi(";
for (const auto &Op : operands()) {
  BasicBlock *BB = getIncomingBlock(Op);
  MemoryAccess *MA = cast<MemoryAccess>(Op);
  if (!First)
    OS << ',';
  else
    First = false;

  OS << '{';
  if (BB->hasName())
    OS << BB->getName();
  else
    BB->printAsOperand(OS, false);
  OS << ',';
  if (unsigned ID = MA->getID())
    OS << ID;
  else
    OS << LiveOnEntryStr;
  OS << '}';
}
OS << ')';
2234}

2236void MemoryUse::print(raw_ostream &OS) const {
MemoryAccess *UO = getDefiningAccess();
OS << "MemoryUse(";
if (UO && UO->getID())
  OS << UO->getID();
else
  OS << LiveOnEntryStr;
OS << ')';

if (Optional<AliasResult> AR = getOptimizedAccessType())
  OS << " " << *AR;
2247}

2249void MemoryAccess::dump() const {
2250// Cannot completely remove virtual function even in release mode.
2251#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
print(dbgs());
dbgs() << "\n";
2254#endif
2255}

2257char MemorySSAPrinterLegacyPass::ID = 0;

2259MemorySSAPrinterLegacyPass::MemorySSAPrinterLegacyPass() : FunctionPass(ID) {
initializeMemorySSAPrinterLegacyPassPass(*PassRegistry::getPassRegistry());
2261}

2263void MemorySSAPrinterLegacyPass::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<MemorySSAWrapperPass>();
2266}

2268class DOTFuncMSSAInfo {
2269private:
const Function &F;
MemorySSAAnnotatedWriter MSSAWriter;

2273public:
DOTFuncMSSAInfo(const Function &F, MemorySSA &MSSA)
    : F(F), MSSAWriter(&MSSA) {}

const Function *getFunction() { return &F; }
MemorySSAAnnotatedWriter &getWriter() { return MSSAWriter; }
2279};

2281namespace llvm {

2283template <>
2284struct GraphTraits<DOTFuncMSSAInfo *> : public GraphTraits<const BasicBlock *> {
static NodeRef getEntryNode(DOTFuncMSSAInfo *CFGInfo) {
  return &(CFGInfo->getFunction()->getEntryBlock());
}

// nodes_iterator/begin/end - Allow iteration over all nodes in the graph
using nodes_iterator = pointer_iterator<Function::const_iterator>;

static nodes_iterator nodes_begin(DOTFuncMSSAInfo *CFGInfo) {
  return nodes_iterator(CFGInfo->getFunction()->begin());
}

static nodes_iterator nodes_end(DOTFuncMSSAInfo *CFGInfo) {
  return nodes_iterator(CFGInfo->getFunction()->end());
}

static size_t size(DOTFuncMSSAInfo *CFGInfo) {
  return CFGInfo->getFunction()->size();
}
2303};

2305template <>
2306struct DOTGraphTraits<DOTFuncMSSAInfo *> : public DefaultDOTGraphTraits {

DOTGraphTraits(bool IsSimple = false) : DefaultDOTGraphTraits(IsSimple) {}

static std::string getGraphName(DOTFuncMSSAInfo *CFGInfo) {
  return "MSSA CFG for '" + CFGInfo->getFunction()->getName().str() +
         "' function";
}

std::string getNodeLabel(const BasicBlock *Node, DOTFuncMSSAInfo *CFGInfo) {
  return DOTGraphTraits<DOTFuncInfo *>::getCompleteNodeLabel(
      Node, nullptr,
      [CFGInfo](raw_string_ostream &OS, const BasicBlock &BB) -> void {
        BB.print(OS, &CFGInfo->getWriter(), true, true);
      },
      [](std::string &S, unsigned &I, unsigned Idx) -> void {
        std::string Str = S.substr(I, Idx - I);
        StringRef SR = Str;
        if (SR.count(" = MemoryDef(") || SR.count(" = MemoryPhi(") ||
            SR.count("MemoryUse("))
          return;
        DOTGraphTraits<DOTFuncInfo *>::eraseComment(S, I, Idx);
      });
}

static std::string getEdgeSourceLabel(const BasicBlock *Node,
                                      const_succ_iterator I) {
  return DOTGraphTraits<DOTFuncInfo *>::getEdgeSourceLabel(Node, I);
}

/// Display the raw branch weights from PGO.
std::string getEdgeAttributes(const BasicBlock *Node, const_succ_iterator I,
                              DOTFuncMSSAInfo *CFGInfo) {
  return "";
}

std::string getNodeAttributes(const BasicBlock *Node,
                              DOTFuncMSSAInfo *CFGInfo) {
  return getNodeLabel(Node, CFGInfo).find(';') != std::string::npos
             ? "style=filled, fillcolor=lightpink"
             : "";
}
2348};

2350} // namespace llvm

2352bool MemorySSAPrinterLegacyPass::runOnFunction(Function &F) {
auto &MSSA = getAnalysis<MemorySSAWrapperPass>().getMSSA();
if (DotCFGMSSA != "") {
  DOTFuncMSSAInfo CFGInfo(F, MSSA);
  WriteGraph(&CFGInfo, "", false, "MSSA", DotCFGMSSA);
} else
  MSSA.print(dbgs());

if (VerifyMemorySSA)
  MSSA.verifyMemorySSA();
return false;
2363}

2365AnalysisKey MemorySSAAnalysis::Key;

2367MemorySSAAnalysis::Result MemorySSAAnalysis::run(Function &F,
                                               FunctionAnalysisManager &AM) {
auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
auto &AA = AM.getResult<AAManager>(F);
return MemorySSAAnalysis::Result(std::make_unique<MemorySSA>(F, &AA, &DT));
2372}

2374bool MemorySSAAnalysis::Result::invalidate(
  Function &F, const PreservedAnalyses &PA,
  FunctionAnalysisManager::Invalidator &Inv) {
auto PAC = PA.getChecker<MemorySSAAnalysis>();
return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>()) ||
       Inv.invalidate<AAManager>(F, PA) ||
       Inv.invalidate<DominatorTreeAnalysis>(F, PA);
2381}

2383PreservedAnalyses MemorySSAPrinterPass::run(Function &F,
                                          FunctionAnalysisManager &AM) {
auto &MSSA = AM.getResult<MemorySSAAnalysis>(F).getMSSA();
if (DotCFGMSSA != "") {
  DOTFuncMSSAInfo CFGInfo(F, MSSA);
  WriteGraph(&CFGInfo, "", false, "MSSA", DotCFGMSSA);
} else {
  OS << "MemorySSA for function: " << F.getName() << "\n";
  MSSA.print(OS);
}

return PreservedAnalyses::all();
2395}

2397PreservedAnalyses MemorySSAVerifierPass::run(Function &F,
                                           FunctionAnalysisManager &AM) {
AM.getResult<MemorySSAAnalysis>(F).getMSSA().verifyMemorySSA();

return PreservedAnalyses::all();
2402}

2404char MemorySSAWrapperPass::ID = 0;

2406MemorySSAWrapperPass::MemorySSAWrapperPass() : FunctionPass(ID) {
initializeMemorySSAWrapperPassPass(*PassRegistry::getPassRegistry());
2408}

2410void MemorySSAWrapperPass::releaseMemory() { MSSA.reset(); }

2412void MemorySSAWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequiredTransitive<DominatorTreeWrapperPass>();
AU.addRequiredTransitive<AAResultsWrapperPass>();
2416}

2418bool MemorySSAWrapperPass::runOnFunction(Function &F) {
auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
auto &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
MSSA.reset(new MemorySSA(F, &AA, &DT));
return false;
2423}

2425void MemorySSAWrapperPass::verifyAnalysis() const {
if (VerifyMemorySSA)
1
Assuming 'VerifyMemorySSA' is true→
2
←
Taking true branch→
  MSSA->verifyMemorySSA();
3
←
Calling 'MemorySSA::verifyMemorySSA'→
2428}

2430void MemorySSAWrapperPass::print(raw_ostream &OS, const Module *M) const {
MSSA->print(OS);
2432}

2434MemorySSAWalker::MemorySSAWalker(MemorySSA *M) : MSSA(M) {}

2436/// Walk the use-def chains starting at \p StartingAccess and find
2437/// the MemoryAccess that actually clobbers Loc.
2438///
2439/// \returns our clobbering memory access
2440template <typename AliasAnalysisType>
2441MemoryAccess *
2442MemorySSA::ClobberWalkerBase<AliasAnalysisType>::getClobberingMemoryAccessBase(
  MemoryAccess *StartingAccess, const MemoryLocation &Loc,
  unsigned &UpwardWalkLimit) {
if (isa<MemoryPhi>(StartingAccess))
  return StartingAccess;

auto *StartingUseOrDef = cast<MemoryUseOrDef>(StartingAccess);
if (MSSA->isLiveOnEntryDef(StartingUseOrDef))
  return StartingUseOrDef;

Instruction *I = StartingUseOrDef->getMemoryInst();

// Conservatively, fences are always clobbers, so don't perform the walk if we
// hit a fence.
if (!isa<CallBase>(I) && I->isFenceLike())
  return StartingUseOrDef;

UpwardsMemoryQuery Q;
Q.OriginalAccess = StartingUseOrDef;
Q.StartingLoc = Loc;
Q.Inst = nullptr;
Q.IsCall = false;

// Unlike the other function, do not walk to the def of a def, because we are
// handed something we already believe is the clobbering access.
// We never set SkipSelf to true in Q in this method.
MemoryAccess *DefiningAccess = isa<MemoryUse>(StartingUseOrDef)
                                   ? StartingUseOrDef->getDefiningAccess()
                                   : StartingUseOrDef;

MemoryAccess *Clobber =
    Walker.findClobber(DefiningAccess, Q, UpwardWalkLimit);
LLVM_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);
LLVM_DEBUG(dbgs() << *StartingUseOrDef << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << *StartingUseOrDef << "\n"
; } } while (false);
LLVM_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);
LLVM_DEBUG(dbgs() << *Clobber << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << *Clobber << "\n"; } } while
 (false);
return Clobber;
2479}

2481template <typename AliasAnalysisType>
2482MemoryAccess *
2483MemorySSA::ClobberWalkerBase<AliasAnalysisType>::getClobberingMemoryAccessBase(
  MemoryAccess *MA, unsigned &UpwardWalkLimit, bool SkipSelf) {
auto *StartingAccess = dyn_cast<MemoryUseOrDef>(MA);
// If this is a MemoryPhi, we can't do anything.
if (!StartingAccess)
  return MA;

bool IsOptimized = false;

// If this is an already optimized use or def, return the optimized result.
// Note: Currently, we store the optimized def result in a separate field,
// since we can't use the defining access.
if (StartingAccess->isOptimized()) {
  if (!SkipSelf || !isa<MemoryDef>(StartingAccess))
    return StartingAccess->getOptimized();
  IsOptimized = true;
}

const Instruction *I = StartingAccess->getMemoryInst();
// We can't sanely do anything with a fence, since they conservatively clobber
// all memory, and have no locations to get pointers from to try to
// disambiguate.
if (!isa<CallBase>(I) && I->isFenceLike())
  return StartingAccess;

UpwardsMemoryQuery Q(I, StartingAccess);

if (isUseTriviallyOptimizableToLiveOnEntry(*Walker.getAA(), I)) {
  MemoryAccess *LiveOnEntry = MSSA->getLiveOnEntryDef();
  StartingAccess->setOptimized(LiveOnEntry);
  StartingAccess->setOptimizedAccessType(None);
  return LiveOnEntry;
}

MemoryAccess *OptimizedAccess;
if (!IsOptimized) {
  // Start with the thing we already think clobbers this location
  MemoryAccess *DefiningAccess = StartingAccess->getDefiningAccess();

  // At this point, DefiningAccess may be the live on entry def.
  // If it is, we will not get a better result.
  if (MSSA->isLiveOnEntryDef(DefiningAccess)) {
    StartingAccess->setOptimized(DefiningAccess);
    StartingAccess->setOptimizedAccessType(None);
    return DefiningAccess;
  }

  OptimizedAccess = Walker.findClobber(DefiningAccess, Q, UpwardWalkLimit);
  StartingAccess->setOptimized(OptimizedAccess);
  if (MSSA->isLiveOnEntryDef(OptimizedAccess))
    StartingAccess->setOptimizedAccessType(None);
  else if (Q.AR == MustAlias)
    StartingAccess->setOptimizedAccessType(MustAlias);
} else
  OptimizedAccess = StartingAccess->getOptimized();

LLVM_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);
LLVM_DEBUG(dbgs() << *StartingAccess << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << *StartingAccess << "\n"
; } } while (false);
LLVM_DEBUG(dbgs() << "Optimized Memory SSA clobber for " << *I << " is ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "Optimized Memory SSA clobber for "
 << *I << " is "; } } while (false);
LLVM_DEBUG(dbgs() << *OptimizedAccess << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << *OptimizedAccess << "\n"
; } } while (false);

MemoryAccess *Result;
if (SkipSelf && isa<MemoryPhi>(OptimizedAccess) &&
    isa<MemoryDef>(StartingAccess) && UpwardWalkLimit) {
  assert(isa<MemoryDef>(Q.OriginalAccess))((isa<MemoryDef>(Q.OriginalAccess)) ? static_cast<void
> (0) : __assert_fail ("isa<MemoryDef>(Q.OriginalAccess)"
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/lib/Analysis/MemorySSA.cpp"
, 2547, __PRETTY_FUNCTION__));
  Q.SkipSelfAccess = true;
  Result = Walker.findClobber(OptimizedAccess, Q, UpwardWalkLimit);
} else
  Result = OptimizedAccess;

LLVM_DEBUG(dbgs() << "Result Memory SSA clobber [SkipSelf = " << SkipSelf)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "Result Memory SSA clobber [SkipSelf = "
 << SkipSelf; } } while (false);
LLVM_DEBUG(dbgs() << "] for " << *I << " is " << *Result << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "] for " << *I <<
 " is " << *Result << "\n"; } } while (false);

return Result;
2557}

2559MemoryAccess *
2560DoNothingMemorySSAWalker::getClobberingMemoryAccess(MemoryAccess *MA) {
if (auto *Use = dyn_cast<MemoryUseOrDef>(MA))
  return Use->getDefiningAccess();
return MA;
2564}

2566MemoryAccess *DoNothingMemorySSAWalker::getClobberingMemoryAccess(
  MemoryAccess *StartingAccess, const MemoryLocation &) {
if (auto *Use = dyn_cast<MemoryUseOrDef>(StartingAccess))
  return Use->getDefiningAccess();
return StartingAccess;
2571}

2573void MemoryPhi::deleteMe(DerivedUser *Self) {
delete static_cast<MemoryPhi *>(Self);
2575}

2577void MemoryDef::deleteMe(DerivedUser *Self) {
delete static_cast<MemoryDef *>(Self);
2579}

2581void MemoryUse::deleteMe(DerivedUser *Self) {
delete static_cast<MemoryUse *>(Self);
2583}

←

/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h

1//===- MemorySSA.h - Build Memory SSA ---------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9/// \file
10/// This file exposes an interface to building/using memory SSA to
11/// walk memory instructions using a use/def graph.
12///
13/// Memory SSA class builds an SSA form that links together memory access
14/// instructions such as loads, stores, atomics, and calls. Additionally, it
15/// does a trivial form of "heap versioning" Every time the memory state changes
16/// in the program, we generate a new heap version. It generates
17/// MemoryDef/Uses/Phis that are overlayed on top of the existing instructions.
18///
19/// As a trivial example,
20/// define i32 @main() #0 {
21/// entry:
22///   %call = call noalias i8* @_Znwm(i64 4) #2
23///   %0 = bitcast i8* %call to i32*
24///   %call1 = call noalias i8* @_Znwm(i64 4) #2
25///   %1 = bitcast i8* %call1 to i32*
26///   store i32 5, i32* %0, align 4
27///   store i32 7, i32* %1, align 4
28///   %2 = load i32* %0, align 4
29///   %3 = load i32* %1, align 4
30///   %add = add nsw i32 %2, %3
31///   ret i32 %add
32/// }
33///
34/// Will become
35/// define i32 @main() #0 {
36/// entry:
37///   ; 1 = MemoryDef(0)
38///   %call = call noalias i8* @_Znwm(i64 4) #3
39///   %2 = bitcast i8* %call to i32*
40///   ; 2 = MemoryDef(1)
41///   %call1 = call noalias i8* @_Znwm(i64 4) #3
42///   %4 = bitcast i8* %call1 to i32*
43///   ; 3 = MemoryDef(2)
44///   store i32 5, i32* %2, align 4
45///   ; 4 = MemoryDef(3)
46///   store i32 7, i32* %4, align 4
47///   ; MemoryUse(3)
48///   %7 = load i32* %2, align 4
49///   ; MemoryUse(4)
50///   %8 = load i32* %4, align 4
51///   %add = add nsw i32 %7, %8
52///   ret i32 %add
53/// }
54///
55/// Given this form, all the stores that could ever effect the load at %8 can be
56/// gotten by using the MemoryUse associated with it, and walking from use to
57/// def until you hit the top of the function.
58///
59/// Each def also has a list of users associated with it, so you can walk from
60/// both def to users, and users to defs. Note that we disambiguate MemoryUses,
61/// but not the RHS of MemoryDefs. You can see this above at %7, which would
62/// otherwise be a MemoryUse(4). Being disambiguated means that for a given
63/// store, all the MemoryUses on its use lists are may-aliases of that store
64/// (but the MemoryDefs on its use list may not be).
65///
66/// MemoryDefs are not disambiguated because it would require multiple reaching
67/// definitions, which would require multiple phis, and multiple memoryaccesses
68/// per instruction.
69//
70//===----------------------------------------------------------------------===//
71 
72#ifndef LLVM_ANALYSIS_MEMORYSSA_H
73#define LLVM_ANALYSIS_MEMORYSSA_H
74 
75#include "llvm/ADT/DenseMap.h"
76#include "llvm/ADT/GraphTraits.h"
77#include "llvm/ADT/SmallPtrSet.h"
78#include "llvm/ADT/SmallVector.h"
79#include "llvm/ADT/ilist.h"
80#include "llvm/ADT/ilist_node.h"
81#include "llvm/ADT/iterator.h"
82#include "llvm/ADT/iterator_range.h"
83#include "llvm/ADT/simple_ilist.h"
84#include "llvm/Analysis/AliasAnalysis.h"
85#include "llvm/Analysis/MemoryLocation.h"
86#include "llvm/Analysis/PHITransAddr.h"
87#include "llvm/IR/BasicBlock.h"
88#include "llvm/IR/DerivedUser.h"
89#include "llvm/IR/Dominators.h"
90#include "llvm/IR/Module.h"
91#include "llvm/IR/Operator.h"
92#include "llvm/IR/Type.h"
93#include "llvm/IR/Use.h"
94#include "llvm/IR/User.h"
95#include "llvm/IR/Value.h"
96#include "llvm/IR/ValueHandle.h"
97#include "llvm/Pass.h"
98#include "llvm/Support/Casting.h"
99#include "llvm/Support/CommandLine.h"
100#include <algorithm>
101#include <cassert>
102#include <cstddef>
103#include <iterator>
104#include <memory>
105#include <utility>
106 
107namespace llvm {
108 
109/// Enables memory ssa as a dependency for loop passes.
110extern cl::opt<bool> EnableMSSALoopDependency;
111 
112class Function;
113class Instruction;
114class MemoryAccess;
115class MemorySSAWalker;
116class LLVMContext;
117class raw_ostream;
118 
119namespace MSSAHelpers {
120 
121struct AllAccessTag {};
122struct DefsOnlyTag {};
123 
124} // end namespace MSSAHelpers
125 
126enum : unsigned {
127  // Used to signify what the default invalid ID is for MemoryAccess's
128  // getID()
129  INVALID_MEMORYACCESS_ID = -1U
130};
131 
132template <class T> class memoryaccess_def_iterator_base;
133using memoryaccess_def_iterator = memoryaccess_def_iterator_base<MemoryAccess>;
134using const_memoryaccess_def_iterator =
135    memoryaccess_def_iterator_base<const MemoryAccess>;
136 
137// The base for all memory accesses. All memory accesses in a block are
138// linked together using an intrusive list.
139class MemoryAccess
140    : public DerivedUser,
141      public ilist_node<MemoryAccess, ilist_tag<MSSAHelpers::AllAccessTag>>,
142      public ilist_node<MemoryAccess, ilist_tag<MSSAHelpers::DefsOnlyTag>> {
143public:
144  using AllAccessType =
145      ilist_node<MemoryAccess, ilist_tag<MSSAHelpers::AllAccessTag>>;
146  using DefsOnlyType =
147      ilist_node<MemoryAccess, ilist_tag<MSSAHelpers::DefsOnlyTag>>;
148 
149  MemoryAccess(const MemoryAccess &) = delete;
150  MemoryAccess &operator=(const MemoryAccess &) = delete;
151 
152  void *operator new(size_t) = delete;
153 
154  // Methods for support type inquiry through isa, cast, and
155  // dyn_cast
156  static bool classof(const Value *V) {
157    unsigned ID = V->getValueID();
158    return ID == MemoryUseVal || ID == MemoryPhiVal || ID == MemoryDefVal;
159  }
160 
161  BasicBlock *getBlock() const { return Block; }
162 
163  void print(raw_ostream &OS) const;
164  void dump() const;
165 
166  /// The user iterators for a memory access
167  using iterator = user_iterator;
168  using const_iterator = const_user_iterator;
169 
170  /// This iterator walks over all of the defs in a given
171  /// MemoryAccess. For MemoryPhi nodes, this walks arguments. For
172  /// MemoryUse/MemoryDef, this walks the defining access.
173  memoryaccess_def_iterator defs_begin();
174  const_memoryaccess_def_iterator defs_begin() const;
175  memoryaccess_def_iterator defs_end();
176  const_memoryaccess_def_iterator defs_end() const;
177 
178  /// Get the iterators for the all access list and the defs only list
179  /// We default to the all access list.
180  AllAccessType::self_iterator getIterator() {
181    return this->AllAccessType::getIterator();
182  }
183  AllAccessType::const_self_iterator getIterator() const {
184    return this->AllAccessType::getIterator();
185  }
186  AllAccessType::reverse_self_iterator getReverseIterator() {
187    return this->AllAccessType::getReverseIterator();
188  }
189  AllAccessType::const_reverse_self_iterator getReverseIterator() const {
190    return this->AllAccessType::getReverseIterator();
191  }
192  DefsOnlyType::self_iterator getDefsIterator() {
193    return this->DefsOnlyType::getIterator();
194  }
195  DefsOnlyType::const_self_iterator getDefsIterator() const {
196    return this->DefsOnlyType::getIterator();
197  }
198  DefsOnlyType::reverse_self_iterator getReverseDefsIterator() {
199    return this->DefsOnlyType::getReverseIterator();
200  }
201  DefsOnlyType::const_reverse_self_iterator getReverseDefsIterator() const {
202    return this->DefsOnlyType::getReverseIterator();
203  }
204 
205protected:
206  friend class MemoryDef;
207  friend class MemoryPhi;
208  friend class MemorySSA;
209  friend class MemoryUse;
210  friend class MemoryUseOrDef;
211 
212  /// Used by MemorySSA to change the block of a MemoryAccess when it is
213  /// moved.
214  void setBlock(BasicBlock *BB) { Block = BB; }
215 
216  /// Used for debugging and tracking things about MemoryAccesses.
217  /// Guaranteed unique among MemoryAccesses, no guarantees otherwise.
218  inline unsigned getID() const;
219 
220  MemoryAccess(LLVMContext &C, unsigned Vty, DeleteValueTy DeleteValue,
221               BasicBlock *BB, unsigned NumOperands)
222      : DerivedUser(Type::getVoidTy(C), Vty, nullptr, NumOperands, DeleteValue),
223        Block(BB) {}
224 
225  // Use deleteValue() to delete a generic MemoryAccess.
226  ~MemoryAccess() = default;
227 
228private:
229  BasicBlock *Block;
230};
231 
232template <>
233struct ilist_alloc_traits<MemoryAccess> {
234  static void deleteNode(MemoryAccess *MA) { MA->deleteValue(); }
235};
236 
237inline raw_ostream &operator<<(raw_ostream &OS, const MemoryAccess &MA) {
238  MA.print(OS);
239  return OS;
240}
241 
242/// Class that has the common methods + fields of memory uses/defs. It's
243/// a little awkward to have, but there are many cases where we want either a
244/// use or def, and there are many cases where uses are needed (defs aren't
245/// acceptable), and vice-versa.
246///
247/// This class should never be instantiated directly; make a MemoryUse or
248/// MemoryDef instead.
249class MemoryUseOrDef : public MemoryAccess {
250public:
251  void *operator new(size_t) = delete;
252 
253  DECLARE_TRANSPARENT_OPERAND_ACCESSORS(MemoryAccess)public: inline MemoryAccess *getOperand(unsigned) const; inline
 void setOperand(unsigned, MemoryAccess*); inline op_iterator
 op_begin(); inline const_op_iterator op_begin() const; inline
 op_iterator op_end(); inline const_op_iterator op_end() const
; protected: template <int> inline Use &Op(); template
 <int> inline const Use &Op() const; public: inline
 unsigned getNumOperands() const;
254 
255  /// Get the instruction that this MemoryUse represents.
256  Instruction *getMemoryInst() const { return MemoryInstruction; }
257 
258  /// Get the access that produces the memory state used by this Use.
259  MemoryAccess *getDefiningAccess() const { return getOperand(0); }
260 
261  static bool classof(const Value *MA) {
262    return MA->getValueID() == MemoryUseVal || MA->getValueID() == MemoryDefVal;
263  }
264 
265  // Sadly, these have to be public because they are needed in some of the
266  // iterators.
267  inline bool isOptimized() const;
268  inline MemoryAccess *getOptimized() const;
269  inline void setOptimized(MemoryAccess *);
270 
271  // Retrieve AliasResult type of the optimized access. Ideally this would be
272  // returned by the caching walker and may go away in the future.
273  Optional<AliasResult> getOptimizedAccessType() const {
274    return isOptimized() ? OptimizedAccessAlias : None;
275  }
276 
277  /// Reset the ID of what this MemoryUse was optimized to, causing it to
278  /// be rewalked by the walker if necessary.
279  /// This really should only be called by tests.
280  inline void resetOptimized();
281 
282protected:
283  friend class MemorySSA;
284  friend class MemorySSAUpdater;
285 
286  MemoryUseOrDef(LLVMContext &C, MemoryAccess *DMA, unsigned Vty,
287                 DeleteValueTy DeleteValue, Instruction *MI, BasicBlock *BB,
288                 unsigned NumOperands)
289      : MemoryAccess(C, Vty, DeleteValue, BB, NumOperands),
290        MemoryInstruction(MI), OptimizedAccessAlias(MayAlias) {
291    setDefiningAccess(DMA);
292  }
293 
294  // Use deleteValue() to delete a generic MemoryUseOrDef.
295  ~MemoryUseOrDef() = default;
296 
297  void setOptimizedAccessType(Optional<AliasResult> AR) {
298    OptimizedAccessAlias = AR;
299  }
300 
301  void setDefiningAccess(MemoryAccess *DMA, bool Optimized = false,
302                         Optional<AliasResult> AR = MayAlias) {
303    if (!Optimized) {
304      setOperand(0, DMA);
305      return;
306    }
307    setOptimized(DMA);
308    setOptimizedAccessType(AR);
309  }
310 
311private:
312  Instruction *MemoryInstruction;
313  Optional<AliasResult> OptimizedAccessAlias;
314};
315 
316/// Represents read-only accesses to memory
317///
318/// In particular, the set of Instructions that will be represented by
319/// MemoryUse's is exactly the set of Instructions for which
320/// AliasAnalysis::getModRefInfo returns "Ref".
321class MemoryUse final : public MemoryUseOrDef {
322public:
323  DECLARE_TRANSPARENT_OPERAND_ACCESSORS(MemoryAccess)public: inline MemoryAccess *getOperand(unsigned) const; inline
 void setOperand(unsigned, MemoryAccess*); inline op_iterator
 op_begin(); inline const_op_iterator op_begin() const; inline
 op_iterator op_end(); inline const_op_iterator op_end() const
; protected: template <int> inline Use &Op(); template
 <int> inline const Use &Op() const; public: inline
 unsigned getNumOperands() const;
324 
325  MemoryUse(LLVMContext &C, MemoryAccess *DMA, Instruction *MI, BasicBlock *BB)
326      : MemoryUseOrDef(C, DMA, MemoryUseVal, deleteMe, MI, BB,
327                       /*NumOperands=*/1) {}
328 
329  // allocate space for exactly one operand
330  void *operator new(size_t s) { return User::operator new(s, 1); }
331 
332  static bool classof(const Value *MA) {
333    return MA->getValueID() == MemoryUseVal;
334  }
335 
336  void print(raw_ostream &OS) const;
337 
338  void setOptimized(MemoryAccess *DMA) {
339    OptimizedID = DMA->getID();
340    setOperand(0, DMA);
341  }
342 
343  bool isOptimized() const {
344    return getDefiningAccess() && OptimizedID == getDefiningAccess()->getID();
345  }
346 
347  MemoryAccess *getOptimized() const {
348    return getDefiningAccess();
349  }
350 
351  void resetOptimized() {
352    OptimizedID = INVALID_MEMORYACCESS_ID;
353  }
354 
355protected:
356  friend class MemorySSA;
357 
358private:
359  static void deleteMe(DerivedUser *Self);
360 
361  unsigned OptimizedID = INVALID_MEMORYACCESS_ID;
362};
363 
364template <>
365struct OperandTraits<MemoryUse> : public FixedNumOperandTraits<MemoryUse, 1> {};
366DEFINE_TRANSPARENT_OPERAND_ACCESSORS(MemoryUse, MemoryAccess)MemoryUse::op_iterator MemoryUse::op_begin() { return OperandTraits
<MemoryUse>::op_begin(this); } MemoryUse::const_op_iterator
 MemoryUse::op_begin() const { return OperandTraits<MemoryUse
>::op_begin(const_cast<MemoryUse*>(this)); } MemoryUse
::op_iterator MemoryUse::op_end() { return OperandTraits<MemoryUse
>::op_end(this); } MemoryUse::const_op_iterator MemoryUse::
op_end() const { return OperandTraits<MemoryUse>::op_end
(const_cast<MemoryUse*>(this)); } MemoryAccess *MemoryUse
::getOperand(unsigned i_nocapture) const { ((i_nocapture <
 OperandTraits<MemoryUse>::operands(this) && "getOperand() out of range!"
) ? static_cast<void> (0) : __assert_fail ("i_nocapture < OperandTraits<MemoryUse>::operands(this) && \"getOperand() out of range!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 366, __PRETTY_FUNCTION__)); return cast_or_null<MemoryAccess
>( OperandTraits<MemoryUse>::op_begin(const_cast<
MemoryUse*>(this))[i_nocapture].get()); } void MemoryUse::
setOperand(unsigned i_nocapture, MemoryAccess *Val_nocapture)
 { ((i_nocapture < OperandTraits<MemoryUse>::operands
(this) && "setOperand() out of range!") ? static_cast
<void> (0) : __assert_fail ("i_nocapture < OperandTraits<MemoryUse>::operands(this) && \"setOperand() out of range!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 366, __PRETTY_FUNCTION__)); OperandTraits<MemoryUse>::
op_begin(this)[i_nocapture] = Val_nocapture; } unsigned MemoryUse
::getNumOperands() const { return OperandTraits<MemoryUse>
::operands(this); } template <int Idx_nocapture> Use &
MemoryUse::Op() { return this->OpFrom<Idx_nocapture>
(this); } template <int Idx_nocapture> const Use &MemoryUse
::Op() const { return this->OpFrom<Idx_nocapture>(this
); }
367 
368/// Represents a read-write access to memory, whether it is a must-alias,
369/// or a may-alias.
370///
371/// In particular, the set of Instructions that will be represented by
372/// MemoryDef's is exactly the set of Instructions for which
373/// AliasAnalysis::getModRefInfo returns "Mod" or "ModRef".
374/// Note that, in order to provide def-def chains, all defs also have a use
375/// associated with them. This use points to the nearest reaching
376/// MemoryDef/MemoryPhi.
377class MemoryDef final : public MemoryUseOrDef {
378public:
379  friend class MemorySSA;
380 
381  DECLARE_TRANSPARENT_OPERAND_ACCESSORS(MemoryAccess)public: inline MemoryAccess *getOperand(unsigned) const; inline
 void setOperand(unsigned, MemoryAccess*); inline op_iterator
 op_begin(); inline const_op_iterator op_begin() const; inline
 op_iterator op_end(); inline const_op_iterator op_end() const
; protected: template <int> inline Use &Op(); template
 <int> inline const Use &Op() const; public: inline
 unsigned getNumOperands() const;
382 
383  MemoryDef(LLVMContext &C, MemoryAccess *DMA, Instruction *MI, BasicBlock *BB,
384            unsigned Ver)
385      : MemoryUseOrDef(C, DMA, MemoryDefVal, deleteMe, MI, BB,
386                       /*NumOperands=*/2),
387        ID(Ver) {}
388 
389  // allocate space for exactly two operands
390  void *operator new(size_t s) { return User::operator new(s, 2); }
391 
392  static bool classof(const Value *MA) {
393    return MA->getValueID() == MemoryDefVal;
394  }
395 
396  void setOptimized(MemoryAccess *MA) {
397    setOperand(1, MA);
398    OptimizedID = MA->getID();
399  }
400 
401  MemoryAccess *getOptimized() const {
402    return cast_or_null<MemoryAccess>(getOperand(1));
403  }
404 
405  bool isOptimized() const {
406    return getOptimized() && OptimizedID == getOptimized()->getID();
407  }
408 
409  void resetOptimized() {
410    OptimizedID = INVALID_MEMORYACCESS_ID;
411    setOperand(1, nullptr);
412  }
413 
414  void print(raw_ostream &OS) const;
415 
416  unsigned getID() const { return ID; }
417 
418private:
419  static void deleteMe(DerivedUser *Self);
420 
421  const unsigned ID;
422  unsigned OptimizedID = INVALID_MEMORYACCESS_ID;
423};
424 
425template <>
426struct OperandTraits<MemoryDef> : public FixedNumOperandTraits<MemoryDef, 2> {};
427DEFINE_TRANSPARENT_OPERAND_ACCESSORS(MemoryDef, MemoryAccess)MemoryDef::op_iterator MemoryDef::op_begin() { return OperandTraits
<MemoryDef>::op_begin(this); } MemoryDef::const_op_iterator
 MemoryDef::op_begin() const { return OperandTraits<MemoryDef
>::op_begin(const_cast<MemoryDef*>(this)); } MemoryDef
::op_iterator MemoryDef::op_end() { return OperandTraits<MemoryDef
>::op_end(this); } MemoryDef::const_op_iterator MemoryDef::
op_end() const { return OperandTraits<MemoryDef>::op_end
(const_cast<MemoryDef*>(this)); } MemoryAccess *MemoryDef
::getOperand(unsigned i_nocapture) const { ((i_nocapture <
 OperandTraits<MemoryDef>::operands(this) && "getOperand() out of range!"
) ? static_cast<void> (0) : __assert_fail ("i_nocapture < OperandTraits<MemoryDef>::operands(this) && \"getOperand() out of range!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 427, __PRETTY_FUNCTION__)); return cast_or_null<MemoryAccess
>( OperandTraits<MemoryDef>::op_begin(const_cast<
MemoryDef*>(this))[i_nocapture].get()); } void MemoryDef::
setOperand(unsigned i_nocapture, MemoryAccess *Val_nocapture)
 { ((i_nocapture < OperandTraits<MemoryDef>::operands
(this) && "setOperand() out of range!") ? static_cast
<void> (0) : __assert_fail ("i_nocapture < OperandTraits<MemoryDef>::operands(this) && \"setOperand() out of range!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 427, __PRETTY_FUNCTION__)); OperandTraits<MemoryDef>::
op_begin(this)[i_nocapture] = Val_nocapture; } unsigned MemoryDef
::getNumOperands() const { return OperandTraits<MemoryDef>
::operands(this); } template <int Idx_nocapture> Use &
MemoryDef::Op() { return this->OpFrom<Idx_nocapture>
(this); } template <int Idx_nocapture> const Use &MemoryDef
::Op() const { return this->OpFrom<Idx_nocapture>(this
); }
428 
429template <>
430struct OperandTraits<MemoryUseOrDef> {
431  static Use *op_begin(MemoryUseOrDef *MUD) {
432    if (auto *MU = dyn_cast<MemoryUse>(MUD))
433      return OperandTraits<MemoryUse>::op_begin(MU);
434    return OperandTraits<MemoryDef>::op_begin(cast<MemoryDef>(MUD));
435  }
436 
437  static Use *op_end(MemoryUseOrDef *MUD) {
438    if (auto *MU = dyn_cast<MemoryUse>(MUD))
439      return OperandTraits<MemoryUse>::op_end(MU);
440    return OperandTraits<MemoryDef>::op_end(cast<MemoryDef>(MUD));
441  }
442 
443  static unsigned operands(const MemoryUseOrDef *MUD) {
444    if (const auto *MU = dyn_cast<MemoryUse>(MUD))
445      return OperandTraits<MemoryUse>::operands(MU);
446    return OperandTraits<MemoryDef>::operands(cast<MemoryDef>(MUD));
447  }
448};
449DEFINE_TRANSPARENT_OPERAND_ACCESSORS(MemoryUseOrDef, MemoryAccess)MemoryUseOrDef::op_iterator MemoryUseOrDef::op_begin() { return
 OperandTraits<MemoryUseOrDef>::op_begin(this); } MemoryUseOrDef
::const_op_iterator MemoryUseOrDef::op_begin() const { return
 OperandTraits<MemoryUseOrDef>::op_begin(const_cast<
MemoryUseOrDef*>(this)); } MemoryUseOrDef::op_iterator MemoryUseOrDef
::op_end() { return OperandTraits<MemoryUseOrDef>::op_end
(this); } MemoryUseOrDef::const_op_iterator MemoryUseOrDef::op_end
() const { return OperandTraits<MemoryUseOrDef>::op_end
(const_cast<MemoryUseOrDef*>(this)); } MemoryAccess *MemoryUseOrDef
::getOperand(unsigned i_nocapture) const { ((i_nocapture <
 OperandTraits<MemoryUseOrDef>::operands(this) &&
 "getOperand() out of range!") ? static_cast<void> (0) :
 __assert_fail ("i_nocapture < OperandTraits<MemoryUseOrDef>::operands(this) && \"getOperand() out of range!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 449, __PRETTY_FUNCTION__)); return cast_or_null<MemoryAccess
>( OperandTraits<MemoryUseOrDef>::op_begin(const_cast
<MemoryUseOrDef*>(this))[i_nocapture].get()); } void MemoryUseOrDef
::setOperand(unsigned i_nocapture, MemoryAccess *Val_nocapture
) { ((i_nocapture < OperandTraits<MemoryUseOrDef>::operands
(this) && "setOperand() out of range!") ? static_cast
<void> (0) : __assert_fail ("i_nocapture < OperandTraits<MemoryUseOrDef>::operands(this) && \"setOperand() out of range!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 449, __PRETTY_FUNCTION__)); OperandTraits<MemoryUseOrDef
>::op_begin(this)[i_nocapture] = Val_nocapture; } unsigned
 MemoryUseOrDef::getNumOperands() const { return OperandTraits
<MemoryUseOrDef>::operands(this); } template <int Idx_nocapture
> Use &MemoryUseOrDef::Op() { return this->OpFrom<
Idx_nocapture>(this); } template <int Idx_nocapture>
 const Use &MemoryUseOrDef::Op() const { return this->
OpFrom<Idx_nocapture>(this); }
450 
451/// Represents phi nodes for memory accesses.
452///
453/// These have the same semantic as regular phi nodes, with the exception that
454/// only one phi will ever exist in a given basic block.
455/// Guaranteeing one phi per block means guaranteeing there is only ever one
456/// valid reaching MemoryDef/MemoryPHI along each path to the phi node.
457/// This is ensured by not allowing disambiguation of the RHS of a MemoryDef or
458/// a MemoryPhi's operands.
459/// That is, given
460/// if (a) {
461///   store %a
462///   store %b
463/// }
464/// it *must* be transformed into
465/// if (a) {
466///    1 = MemoryDef(liveOnEntry)
467///    store %a
468///    2 = MemoryDef(1)
469///    store %b
470/// }
471/// and *not*
472/// if (a) {
473///    1 = MemoryDef(liveOnEntry)
474///    store %a
475///    2 = MemoryDef(liveOnEntry)
476///    store %b
477/// }
478/// even if the two stores do not conflict. Otherwise, both 1 and 2 reach the
479/// end of the branch, and if there are not two phi nodes, one will be
480/// disconnected completely from the SSA graph below that point.
481/// Because MemoryUse's do not generate new definitions, they do not have this
482/// issue.
483class MemoryPhi final : public MemoryAccess {
484  // allocate space for exactly zero operands
485  void *operator new(size_t s) { return User::operator new(s); }
486 
487public:
488  /// Provide fast operand accessors
489  DECLARE_TRANSPARENT_OPERAND_ACCESSORS(MemoryAccess)public: inline MemoryAccess *getOperand(unsigned) const; inline
 void setOperand(unsigned, MemoryAccess*); inline op_iterator
 op_begin(); inline const_op_iterator op_begin() const; inline
 op_iterator op_end(); inline const_op_iterator op_end() const
; protected: template <int> inline Use &Op(); template
 <int> inline const Use &Op() const; public: inline
 unsigned getNumOperands() const;
490 
491  MemoryPhi(LLVMContext &C, BasicBlock *BB, unsigned Ver, unsigned NumPreds = 0)
492      : MemoryAccess(C, MemoryPhiVal, deleteMe, BB, 0), ID(Ver),
493        ReservedSpace(NumPreds) {
494    allocHungoffUses(ReservedSpace);
495  }
496 
497  // Block iterator interface. This provides access to the list of incoming
498  // basic blocks, which parallels the list of incoming values.
499  using block_iterator = BasicBlock **;
500  using const_block_iterator = BasicBlock *const *;
501 
502  block_iterator block_begin() {
503    return reinterpret_cast<block_iterator>(op_begin() + ReservedSpace);
504  }
505 
506  const_block_iterator block_begin() const {
507    return reinterpret_cast<const_block_iterator>(op_begin() + ReservedSpace);
508  }
509 
510  block_iterator block_end() { return block_begin() + getNumOperands(); }
511 
512  const_block_iterator block_end() const {
513    return block_begin() + getNumOperands();
514  }
515 
516  iterator_range<block_iterator> blocks() {
517    return make_range(block_begin(), block_end());
518  }
519 
520  iterator_range<const_block_iterator> blocks() const {
521    return make_range(block_begin(), block_end());
522  }
523 
524  op_range incoming_values() { return operands(); }
525 
526  const_op_range incoming_values() const { return operands(); }
527 
528  /// Return the number of incoming edges
529  unsigned getNumIncomingValues() const { return getNumOperands(); }
530 
531  /// Return incoming value number x
532  MemoryAccess *getIncomingValue(unsigned I) const { return getOperand(I); }
533  void setIncomingValue(unsigned I, MemoryAccess *V) {
534    assert(V && "PHI node got a null value!")((V && "PHI node got a null value!") ? static_cast<
void> (0) : __assert_fail ("V && \"PHI node got a null value!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 534, __PRETTY_FUNCTION__));
535    setOperand(I, V);
536  }
537 
538  static unsigned getOperandNumForIncomingValue(unsigned I) { return I; }
539  static unsigned getIncomingValueNumForOperand(unsigned I) { return I; }
540 
541  /// Return incoming basic block number @p i.
542  BasicBlock *getIncomingBlock(unsigned I) const { return block_begin()[I]; }
543 
544  /// Return incoming basic block corresponding
545  /// to an operand of the PHI.
546  BasicBlock *getIncomingBlock(const Use &U) const {
547    assert(this == U.getUser() && "Iterator doesn't point to PHI's Uses?")((this == U.getUser() && "Iterator doesn't point to PHI's Uses?"
) ? static_cast<void> (0) : __assert_fail ("this == U.getUser() && \"Iterator doesn't point to PHI's Uses?\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 547, __PRETTY_FUNCTION__));
548    return getIncomingBlock(unsigned(&U - op_begin()));
549  }
550 
551  /// Return incoming basic block corresponding
552  /// to value use iterator.
553  BasicBlock *getIncomingBlock(MemoryAccess::const_user_iterator I) const {
554    return getIncomingBlock(I.getUse());
555  }
556 
557  void setIncomingBlock(unsigned I, BasicBlock *BB) {
558    assert(BB && "PHI node got a null basic block!")((BB && "PHI node got a null basic block!") ? static_cast
<void> (0) : __assert_fail ("BB && \"PHI node got a null basic block!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 558, __PRETTY_FUNCTION__));
559    block_begin()[I] = BB;
560  }
561 
562  /// Add an incoming value to the end of the PHI list
563  void addIncoming(MemoryAccess *V, BasicBlock *BB) {
564    if (getNumOperands() == ReservedSpace)
565      growOperands(); // Get more space!
566    // Initialize some new operands.
567    setNumHungOffUseOperands(getNumOperands() + 1);
568    setIncomingValue(getNumOperands() - 1, V);
569    setIncomingBlock(getNumOperands() - 1, BB);
570  }
571 
572  /// Return the first index of the specified basic
573  /// block in the value list for this PHI.  Returns -1 if no instance.
574  int getBasicBlockIndex(const BasicBlock *BB) const {
575    for (unsigned I = 0, E = getNumOperands(); I != E; ++I)
576      if (block_begin()[I] == BB)
577        return I;
578    return -1;
579  }
580 
581  MemoryAccess *getIncomingValueForBlock(const BasicBlock *BB) const {
582    int Idx = getBasicBlockIndex(BB);
583    assert(Idx >= 0 && "Invalid basic block argument!")((Idx >= 0 && "Invalid basic block argument!") ? static_cast
<void> (0) : __assert_fail ("Idx >= 0 && \"Invalid basic block argument!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 583, __PRETTY_FUNCTION__));
584    return getIncomingValue(Idx);
585  }
586 
587  // After deleting incoming position I, the order of incoming may be changed.
588  void unorderedDeleteIncoming(unsigned I) {
589    unsigned E = getNumOperands();
590    assert(I < E && "Cannot remove out of bounds Phi entry.")((I < E && "Cannot remove out of bounds Phi entry."
) ? static_cast<void> (0) : __assert_fail ("I < E && \"Cannot remove out of bounds Phi entry.\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 590, __PRETTY_FUNCTION__));
591    // MemoryPhi must have at least two incoming values, otherwise the MemoryPhi
592    // itself should be deleted.
593    assert(E >= 2 && "Cannot only remove incoming values in MemoryPhis with "((E >= 2 && "Cannot only remove incoming values in MemoryPhis with "
 "at least 2 values.") ? static_cast<void> (0) : __assert_fail
 ("E >= 2 && \"Cannot only remove incoming values in MemoryPhis with \" \"at least 2 values.\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 594, __PRETTY_FUNCTION__))
594                     "at least 2 values.")((E >= 2 && "Cannot only remove incoming values in MemoryPhis with "
 "at least 2 values.") ? static_cast<void> (0) : __assert_fail
 ("E >= 2 && \"Cannot only remove incoming values in MemoryPhis with \" \"at least 2 values.\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 594, __PRETTY_FUNCTION__));
595    setIncomingValue(I, getIncomingValue(E - 1));
596    setIncomingBlock(I, block_begin()[E - 1]);
597    setOperand(E - 1, nullptr);
598    block_begin()[E - 1] = nullptr;
599    setNumHungOffUseOperands(getNumOperands() - 1);
600  }
601 
602  // After deleting entries that satisfy Pred, remaining entries may have
603  // changed order.
604  template <typename Fn> void unorderedDeleteIncomingIf(Fn &&Pred) {
605    for (unsigned I = 0, E = getNumOperands(); I != E; ++I)
606      if (Pred(getIncomingValue(I), getIncomingBlock(I))) {
607        unorderedDeleteIncoming(I);
608        E = getNumOperands();
609        --I;
610      }
611    assert(getNumOperands() >= 1 &&((getNumOperands() >= 1 && "Cannot remove all incoming blocks in a MemoryPhi."
) ? static_cast<void> (0) : __assert_fail ("getNumOperands() >= 1 && \"Cannot remove all incoming blocks in a MemoryPhi.\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 612, __PRETTY_FUNCTION__))
612           "Cannot remove all incoming blocks in a MemoryPhi.")((getNumOperands() >= 1 && "Cannot remove all incoming blocks in a MemoryPhi."
) ? static_cast<void> (0) : __assert_fail ("getNumOperands() >= 1 && \"Cannot remove all incoming blocks in a MemoryPhi.\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 612, __PRETTY_FUNCTION__));
613  }
614 
615  // After deleting incoming block BB, the incoming blocks order may be changed.
616  void unorderedDeleteIncomingBlock(const BasicBlock *BB) {
617    unorderedDeleteIncomingIf(
618        [&](const MemoryAccess *, const BasicBlock *B) { return BB == B; });
619  }
620 
621  // After deleting incoming memory access MA, the incoming accesses order may
622  // be changed.
623  void unorderedDeleteIncomingValue(const MemoryAccess *MA) {
624    unorderedDeleteIncomingIf(
625        [&](const MemoryAccess *M, const BasicBlock *) { return MA == M; });
626  }
627 
628  static bool classof(const Value *V) {
629    return V->getValueID() == MemoryPhiVal;
630  }
631 
632  void print(raw_ostream &OS) const;
633 
634  unsigned getID() const { return ID; }
635 
636protected:
637  friend class MemorySSA;
638 
639  /// this is more complicated than the generic
640  /// User::allocHungoffUses, because we have to allocate Uses for the incoming
641  /// values and pointers to the incoming blocks, all in one allocation.
642  void allocHungoffUses(unsigned N) {
643    User::allocHungoffUses(N, /* IsPhi */ true);
644  }
645 
646private:
647  // For debugging only
648  const unsigned ID;
649  unsigned ReservedSpace;
650 
651  /// This grows the operand list in response to a push_back style of
652  /// operation.  This grows the number of ops by 1.5 times.
653  void growOperands() {
654    unsigned E = getNumOperands();
655    // 2 op PHI nodes are VERY common, so reserve at least enough for that.
656    ReservedSpace = std::max(E + E / 2, 2u);
657    growHungoffUses(ReservedSpace, /* IsPhi */ true);
658  }
659 
660  static void deleteMe(DerivedUser *Self);
661};
662 
663inline unsigned MemoryAccess::getID() const {
664  assert((isa<MemoryDef>(this) || isa<MemoryPhi>(this)) &&(((isa<MemoryDef>(this) || isa<MemoryPhi>(this)) &&
 "only memory defs and phis have ids") ? static_cast<void>
 (0) : __assert_fail ("(isa<MemoryDef>(this) || isa<MemoryPhi>(this)) && \"only memory defs and phis have ids\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 665, __PRETTY_FUNCTION__))
665         "only memory defs and phis have ids")(((isa<MemoryDef>(this) || isa<MemoryPhi>(this)) &&
 "only memory defs and phis have ids") ? static_cast<void>
 (0) : __assert_fail ("(isa<MemoryDef>(this) || isa<MemoryPhi>(this)) && \"only memory defs and phis have ids\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 665, __PRETTY_FUNCTION__));
666  if (const auto *MD = dyn_cast<MemoryDef>(this))
667    return MD->getID();
668  return cast<MemoryPhi>(this)->getID();
669}
670 
671inline bool MemoryUseOrDef::isOptimized() const {
672  if (const auto *MD = dyn_cast<MemoryDef>(this))
673    return MD->isOptimized();
674  return cast<MemoryUse>(this)->isOptimized();
675}
676 
677inline MemoryAccess *MemoryUseOrDef::getOptimized() const {
678  if (const auto *MD = dyn_cast<MemoryDef>(this))
679    return MD->getOptimized();
680  return cast<MemoryUse>(this)->getOptimized();
681}
682 
683inline void MemoryUseOrDef::setOptimized(MemoryAccess *MA) {
684  if (auto *MD = dyn_cast<MemoryDef>(this))
685    MD->setOptimized(MA);
686  else
687    cast<MemoryUse>(this)->setOptimized(MA);
688}
689 
690inline void MemoryUseOrDef::resetOptimized() {
691  if (auto *MD = dyn_cast<MemoryDef>(this))
692    MD->resetOptimized();
693  else
694    cast<MemoryUse>(this)->resetOptimized();
695}
696 
697template <> struct OperandTraits<MemoryPhi> : public HungoffOperandTraits<2> {};
698DEFINE_TRANSPARENT_OPERAND_ACCESSORS(MemoryPhi, MemoryAccess)MemoryPhi::op_iterator MemoryPhi::op_begin() { return OperandTraits
<MemoryPhi>::op_begin(this); } MemoryPhi::const_op_iterator
 MemoryPhi::op_begin() const { return OperandTraits<MemoryPhi
>::op_begin(const_cast<MemoryPhi*>(this)); } MemoryPhi
::op_iterator MemoryPhi::op_end() { return OperandTraits<MemoryPhi
>::op_end(this); } MemoryPhi::const_op_iterator MemoryPhi::
op_end() const { return OperandTraits<MemoryPhi>::op_end
(const_cast<MemoryPhi*>(this)); } MemoryAccess *MemoryPhi
::getOperand(unsigned i_nocapture) const { ((i_nocapture <
 OperandTraits<MemoryPhi>::operands(this) && "getOperand() out of range!"
) ? static_cast<void> (0) : __assert_fail ("i_nocapture < OperandTraits<MemoryPhi>::operands(this) && \"getOperand() out of range!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 698, __PRETTY_FUNCTION__)); return cast_or_null<MemoryAccess
>( OperandTraits<MemoryPhi>::op_begin(const_cast<
MemoryPhi*>(this))[i_nocapture].get()); } void MemoryPhi::
setOperand(unsigned i_nocapture, MemoryAccess *Val_nocapture)
 { ((i_nocapture < OperandTraits<MemoryPhi>::operands
(this) && "setOperand() out of range!") ? static_cast
<void> (0) : __assert_fail ("i_nocapture < OperandTraits<MemoryPhi>::operands(this) && \"setOperand() out of range!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 698, __PRETTY_FUNCTION__)); OperandTraits<MemoryPhi>::
op_begin(this)[i_nocapture] = Val_nocapture; } unsigned MemoryPhi
::getNumOperands() const { return OperandTraits<MemoryPhi>
::operands(this); } template <int Idx_nocapture> Use &
MemoryPhi::Op() { return this->OpFrom<Idx_nocapture>
(this); } template <int Idx_nocapture> const Use &MemoryPhi
::Op() const { return this->OpFrom<Idx_nocapture>(this
); }
699 
700/// Encapsulates MemorySSA, including all data associated with memory
701/// accesses.
702class MemorySSA {
703public:
704  MemorySSA(Function &, AliasAnalysis *, DominatorTree *);
705 
706  // MemorySSA must remain where it's constructed; Walkers it creates store
707  // pointers to it.
708  MemorySSA(MemorySSA &&) = delete;
709 
710  ~MemorySSA();
711 
712  MemorySSAWalker *getWalker();
713  MemorySSAWalker *getSkipSelfWalker();
714 
715  /// Given a memory Mod/Ref'ing instruction, get the MemorySSA
716  /// access associated with it. If passed a basic block gets the memory phi
717  /// node that exists for that block, if there is one. Otherwise, this will get
718  /// a MemoryUseOrDef.
719  MemoryUseOrDef *getMemoryAccess(const Instruction *I) const {
720    return cast_or_null<MemoryUseOrDef>(ValueToMemoryAccess.lookup(I));
721  }
722 
723  MemoryPhi *getMemoryAccess(const BasicBlock *BB) const {
724    return cast_or_null<MemoryPhi>(ValueToMemoryAccess.lookup(cast<Value>(BB)));
25
←
'BB' is a 'Value'→
26
←
Assuming null pointer is passed into cast→
27
←
Returning null pointer, which participates in a condition later→
725  }
726 
727  DominatorTree &getDomTree() const { return *DT; }
728 
729  void dump() const;
730  void print(raw_ostream &) const;
731 
732  /// Return true if \p MA represents the live on entry value
733  ///
734  /// Loads and stores from pointer arguments and other global values may be
735  /// defined by memory operations that do not occur in the current function, so
736  /// they may be live on entry to the function. MemorySSA represents such
737  /// memory state by the live on entry definition, which is guaranteed to occur
738  /// before any other memory access in the function.
739  inline bool isLiveOnEntryDef(const MemoryAccess *MA) const {
740    return MA == LiveOnEntryDef.get();
741  }
742 
743  inline MemoryAccess *getLiveOnEntryDef() const {
744    return LiveOnEntryDef.get();
745  }
746 
747  // Sadly, iplists, by default, owns and deletes pointers added to the
748  // list. It's not currently possible to have two iplists for the same type,
749  // where one owns the pointers, and one does not. This is because the traits
750  // are per-type, not per-tag.  If this ever changes, we should make the
751  // DefList an iplist.
752  using AccessList = iplist<MemoryAccess, ilist_tag<MSSAHelpers::AllAccessTag>>;
753  using DefsList =
754      simple_ilist<MemoryAccess, ilist_tag<MSSAHelpers::DefsOnlyTag>>;
755 
756  /// Return the list of MemoryAccess's for a given basic block.
757  ///
758  /// This list is not modifiable by the user.
759  const AccessList *getBlockAccesses(const BasicBlock *BB) const {
760    return getWritableBlockAccesses(BB);
6
←
Calling 'MemorySSA::getWritableBlockAccesses'→
11
←
Returning from 'MemorySSA::getWritableBlockAccesses'→
12
←
Returning pointer, which participates in a condition later→
13
←
Returning pointer→
761  }
762 
763  /// Return the list of MemoryDef's and MemoryPhi's for a given basic
764  /// block.
765  ///
766  /// This list is not modifiable by the user.
767  const DefsList *getBlockDefs(const BasicBlock *BB) const {
768    return getWritableBlockDefs(BB);
17
←
Calling 'MemorySSA::getWritableBlockDefs'→
21
←
Returning from 'MemorySSA::getWritableBlockDefs'→
22
←
Returning pointer, which participates in a condition later→
769  }
770 
771  /// Given two memory accesses in the same basic block, determine
772  /// whether MemoryAccess \p A dominates MemoryAccess \p B.
773  bool locallyDominates(const MemoryAccess *A, const MemoryAccess *B) const;
774 
775  /// Given two memory accesses in potentially different blocks,
776  /// determine whether MemoryAccess \p A dominates MemoryAccess \p B.
777  bool dominates(const MemoryAccess *A, const MemoryAccess *B) const;
778 
779  /// Given a MemoryAccess and a Use, determine whether MemoryAccess \p A
780  /// dominates Use \p B.
781  bool dominates(const MemoryAccess *A, const Use &B) const;
782 
783  /// Verify that MemorySSA is self consistent (IE definitions dominate
784  /// all uses, uses appear in the right places).  This is used by unit tests.
785  void verifyMemorySSA() const;
786 
787  /// Used in various insertion functions to specify whether we are talking
788  /// about the beginning or end of a block.
789  enum InsertionPlace { Beginning, End, BeforeTerminator };
790 
791protected:
792  // Used by Memory SSA annotater, dumpers, and wrapper pass
793  friend class MemorySSAAnnotatedWriter;
794  friend class MemorySSAPrinterLegacyPass;
795  friend class MemorySSAUpdater;
796 
797  void verifyOrderingDominationAndDefUses(Function &F) const;
798  void verifyDominationNumbers(const Function &F) const;
799  void verifyPrevDefInPhis(Function &F) const;
800 
801  // This is used by the use optimizer and updater.
802  AccessList *getWritableBlockAccesses(const BasicBlock *BB) const {
803    auto It = PerBlockAccesses.find(BB);
804    return It == PerBlockAccesses.end() ? nullptr : It->second.get();
7
←
Assuming the condition is false→
8
←
'?' condition is false→
9
←
Returning pointer, which participates in a condition later→
10
←
Returning pointer→
805  }
806 
807  // This is used by the use optimizer and updater.
808  DefsList *getWritableBlockDefs(const BasicBlock *BB) const {
809    auto It = PerBlockDefs.find(BB);
810    return It == PerBlockDefs.end() ? nullptr : It->second.get();
18
←
Assuming the condition is false→
19
←
'?' condition is false→
20
←
Returning pointer, which participates in a condition later→
811  }
812 
813  // These is used by the updater to perform various internal MemorySSA
814  // machinsations.  They do not always leave the IR in a correct state, and
815  // relies on the updater to fixup what it breaks, so it is not public.
816 
817  void moveTo(MemoryUseOrDef *What, BasicBlock *BB, AccessList::iterator Where);
818  void moveTo(MemoryAccess *What, BasicBlock *BB, InsertionPlace Point);
819 
820  // Rename the dominator tree branch rooted at BB.
821  void renamePass(BasicBlock *BB, MemoryAccess *IncomingVal,
822                  SmallPtrSetImpl<BasicBlock *> &Visited) {
823    renamePass(DT->getNode(BB), IncomingVal, Visited, true, true);
824  }
825 
826  void removeFromLookups(MemoryAccess *);
827  void removeFromLists(MemoryAccess *, bool ShouldDelete = true);
828  void insertIntoListsForBlock(MemoryAccess *, const BasicBlock *,
829                               InsertionPlace);
830  void insertIntoListsBefore(MemoryAccess *, const BasicBlock *,
831                             AccessList::iterator);
832  MemoryUseOrDef *createDefinedAccess(Instruction *, MemoryAccess *,
833                                      const MemoryUseOrDef *Template = nullptr,
834                                      bool CreationMustSucceed = true);
835 
836private:
837  template <class AliasAnalysisType> class ClobberWalkerBase;
838  template <class AliasAnalysisType> class CachingWalker;
839  template <class AliasAnalysisType> class SkipSelfWalker;
840  class OptimizeUses;
841 
842  CachingWalker<AliasAnalysis> *getWalkerImpl();
843  void buildMemorySSA(BatchAAResults &BAA);
844 
845  void prepareForMoveTo(MemoryAccess *, BasicBlock *);
846  void verifyUseInDefs(MemoryAccess *, MemoryAccess *) const;
847 
848  using AccessMap = DenseMap<const BasicBlock *, std::unique_ptr<AccessList>>;
849  using DefsMap = DenseMap<const BasicBlock *, std::unique_ptr<DefsList>>;
850 
851  void markUnreachableAsLiveOnEntry(BasicBlock *BB);
852  bool dominatesUse(const MemoryAccess *, const MemoryAccess *) const;
853  MemoryPhi *createMemoryPhi(BasicBlock *BB);
854  template <typename AliasAnalysisType>
855  MemoryUseOrDef *createNewAccess(Instruction *, AliasAnalysisType *,
856                                  const MemoryUseOrDef *Template = nullptr);
857  void placePHINodes(const SmallPtrSetImpl<BasicBlock *> &);
858  MemoryAccess *renameBlock(BasicBlock *, MemoryAccess *, bool);
859  void renameSuccessorPhis(BasicBlock *, MemoryAccess *, bool);
860  void renamePass(DomTreeNode *, MemoryAccess *IncomingVal,
861                  SmallPtrSetImpl<BasicBlock *> &Visited,
862                  bool SkipVisited = false, bool RenameAllUses = false);
863  AccessList *getOrCreateAccessList(const BasicBlock *);
864  DefsList *getOrCreateDefsList(const BasicBlock *);
865  void renumberBlock(const BasicBlock *) const;
866  AliasAnalysis *AA;
867  DominatorTree *DT;
868  Function &F;
869 
870  // Memory SSA mappings
871  DenseMap<const Value *, MemoryAccess *> ValueToMemoryAccess;
872 
873  // These two mappings contain the main block to access/def mappings for
874  // MemorySSA. The list contained in PerBlockAccesses really owns all the
875  // MemoryAccesses.
876  // Both maps maintain the invariant that if a block is found in them, the
877  // corresponding list is not empty, and if a block is not found in them, the
878  // corresponding list is empty.
879  AccessMap PerBlockAccesses;
880  DefsMap PerBlockDefs;
881  std::unique_ptr<MemoryAccess, ValueDeleter> LiveOnEntryDef;
882 
883  // Domination mappings
884  // Note that the numbering is local to a block, even though the map is
885  // global.
886  mutable SmallPtrSet<const BasicBlock *, 16> BlockNumberingValid;
887  mutable DenseMap<const MemoryAccess *, unsigned long> BlockNumbering;
888 
889  // Memory SSA building info
890  std::unique_ptr<ClobberWalkerBase<AliasAnalysis>> WalkerBase;
891  std::unique_ptr<CachingWalker<AliasAnalysis>> Walker;
892  std::unique_ptr<SkipSelfWalker<AliasAnalysis>> SkipWalker;
893  unsigned NextID;
894};
895 
896// Internal MemorySSA utils, for use by MemorySSA classes and walkers
897class MemorySSAUtil {
898protected:
899  friend class GVNHoist;
900  friend class MemorySSAWalker;
901 
902  // This function should not be used by new passes.
903  static bool defClobbersUseOrDef(MemoryDef *MD, const MemoryUseOrDef *MU,
904                                  AliasAnalysis &AA);
905};
906 
907// This pass does eager building and then printing of MemorySSA. It is used by
908// the tests to be able to build, dump, and verify Memory SSA.
909class MemorySSAPrinterLegacyPass : public FunctionPass {
910public:
911  MemorySSAPrinterLegacyPass();
912 
913  bool runOnFunction(Function &) override;
914  void getAnalysisUsage(AnalysisUsage &AU) const override;
915 
916  static char ID;
917};
918 
919/// An analysis that produces \c MemorySSA for a function.
920///
921class MemorySSAAnalysis : public AnalysisInfoMixin<MemorySSAAnalysis> {
922  friend AnalysisInfoMixin<MemorySSAAnalysis>;
923 
924  static AnalysisKey Key;
925 
926public:
927  // Wrap MemorySSA result to ensure address stability of internal MemorySSA
928  // pointers after construction.  Use a wrapper class instead of plain
929  // unique_ptr<MemorySSA> to avoid build breakage on MSVC.
930  struct Result {
931    Result(std::unique_ptr<MemorySSA> &&MSSA) : MSSA(std::move(MSSA)) {}
932 
933    MemorySSA &getMSSA() { return *MSSA.get(); }
934 
935    std::unique_ptr<MemorySSA> MSSA;
936 
937    bool invalidate(Function &F, const PreservedAnalyses &PA,
938                    FunctionAnalysisManager::Invalidator &Inv);
939  };
940 
941  Result run(Function &F, FunctionAnalysisManager &AM);
942};
943 
944/// Printer pass for \c MemorySSA.
945class MemorySSAPrinterPass : public PassInfoMixin<MemorySSAPrinterPass> {
946  raw_ostream &OS;
947 
948public:
949  explicit MemorySSAPrinterPass(raw_ostream &OS) : OS(OS) {}
950 
951  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
952};
953 
954/// Verifier pass for \c MemorySSA.
955struct MemorySSAVerifierPass : PassInfoMixin<MemorySSAVerifierPass> {
956  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
957};
958 
959/// Legacy analysis pass which computes \c MemorySSA.
960class MemorySSAWrapperPass : public FunctionPass {
961public:
962  MemorySSAWrapperPass();
963 
964  static char ID;
965 
966  bool runOnFunction(Function &) override;
967  void releaseMemory() override;
968  MemorySSA &getMSSA() { return *MSSA; }
969  const MemorySSA &getMSSA() const { return *MSSA; }
970 
971  void getAnalysisUsage(AnalysisUsage &AU) const override;
972 
973  void verifyAnalysis() const override;
974  void print(raw_ostream &OS, const Module *M = nullptr) const override;
975 
976private:
977  std::unique_ptr<MemorySSA> MSSA;
978};
979 
980/// This is the generic walker interface for walkers of MemorySSA.
981/// Walkers are used to be able to further disambiguate the def-use chains
982/// MemorySSA gives you, or otherwise produce better info than MemorySSA gives
983/// you.
984/// In particular, while the def-use chains provide basic information, and are
985/// guaranteed to give, for example, the nearest may-aliasing MemoryDef for a
986/// MemoryUse as AliasAnalysis considers it, a user mant want better or other
987/// information. In particular, they may want to use SCEV info to further
988/// disambiguate memory accesses, or they may want the nearest dominating
989/// may-aliasing MemoryDef for a call or a store. This API enables a
990/// standardized interface to getting and using that info.
991class MemorySSAWalker {
992public:
993  MemorySSAWalker(MemorySSA *);
994  virtual ~MemorySSAWalker() = default;
995 
996  using MemoryAccessSet = SmallVector<MemoryAccess *, 8>;
997 
998  /// Given a memory Mod/Ref/ModRef'ing instruction, calling this
999  /// will give you the nearest dominating MemoryAccess that Mod's the location
1000  /// the instruction accesses (by skipping any def which AA can prove does not
1001  /// alias the location(s) accessed by the instruction given).
1002  ///
1003  /// Note that this will return a single access, and it must dominate the
1004  /// Instruction, so if an operand of a MemoryPhi node Mod's the instruction,
1005  /// this will return the MemoryPhi, not the operand. This means that
1006  /// given:
1007  /// if (a) {
1008  ///   1 = MemoryDef(liveOnEntry)
1009  ///   store %a
1010  /// } else {
1011  ///   2 = MemoryDef(liveOnEntry)
1012  ///   store %b
1013  /// }
1014  /// 3 = MemoryPhi(2, 1)
1015  /// MemoryUse(3)
1016  /// load %a
1017  ///
1018  /// calling this API on load(%a) will return the MemoryPhi, not the MemoryDef
1019  /// in the if (a) branch.
1020  MemoryAccess *getClobberingMemoryAccess(const Instruction *I) {
1021    MemoryAccess *MA = MSSA->getMemoryAccess(I);
1022    assert(MA && "Handed an instruction that MemorySSA doesn't recognize?")((MA && "Handed an instruction that MemorySSA doesn't recognize?"
) ? static_cast<void> (0) : __assert_fail ("MA && \"Handed an instruction that MemorySSA doesn't recognize?\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 1022, __PRETTY_FUNCTION__));
1023    return getClobberingMemoryAccess(MA);
1024  }
1025 
1026  /// Does the same thing as getClobberingMemoryAccess(const Instruction *I),
1027  /// but takes a MemoryAccess instead of an Instruction.
1028  virtual MemoryAccess *getClobberingMemoryAccess(MemoryAccess *) = 0;
1029 
1030  /// Given a potentially clobbering memory access and a new location,
1031  /// calling this will give you the nearest dominating clobbering MemoryAccess
1032  /// (by skipping non-aliasing def links).
1033  ///
1034  /// This version of the function is mainly used to disambiguate phi translated
1035  /// pointers, where the value of a pointer may have changed from the initial
1036  /// memory access. Note that this expects to be handed either a MemoryUse,
1037  /// or an already potentially clobbering access. Unlike the above API, if
1038  /// given a MemoryDef that clobbers the pointer as the starting access, it
1039  /// will return that MemoryDef, whereas the above would return the clobber
1040  /// starting from the use side of  the memory def.
1041  virtual MemoryAccess *getClobberingMemoryAccess(MemoryAccess *,
1042                                                  const MemoryLocation &) = 0;
1043 
1044  /// Given a memory access, invalidate anything this walker knows about
1045  /// that access.
1046  /// This API is used by walkers that store information to perform basic cache
1047  /// invalidation.  This will be called by MemorySSA at appropriate times for
1048  /// the walker it uses or returns.
1049  virtual void invalidateInfo(MemoryAccess *) {}
1050 
1051protected:
1052  friend class MemorySSA; // For updating MSSA pointer in MemorySSA move
1053                          // constructor.
1054  MemorySSA *MSSA;
1055};
1056 
1057/// A MemorySSAWalker that does no alias queries, or anything else. It
1058/// simply returns the links as they were constructed by the builder.
1059class DoNothingMemorySSAWalker final : public MemorySSAWalker {
1060public:
1061  // Keep the overrides below from hiding the Instruction overload of
1062  // getClobberingMemoryAccess.
1063  using MemorySSAWalker::getClobberingMemoryAccess;
1064 
1065  MemoryAccess *getClobberingMemoryAccess(MemoryAccess *) override;
1066  MemoryAccess *getClobberingMemoryAccess(MemoryAccess *,
1067                                          const MemoryLocation &) override;
1068};
1069 
1070using MemoryAccessPair = std::pair<MemoryAccess *, MemoryLocation>;
1071using ConstMemoryAccessPair = std::pair<const MemoryAccess *, MemoryLocation>;
1072 
1073/// Iterator base class used to implement const and non-const iterators
1074/// over the defining accesses of a MemoryAccess.
1075template <class T>
1076class memoryaccess_def_iterator_base
1077    : public iterator_facade_base<memoryaccess_def_iterator_base<T>,
1078                                  std::forward_iterator_tag, T, ptrdiff_t, T *,
1079                                  T *> {
1080  using BaseT = typename memoryaccess_def_iterator_base::iterator_facade_base;
1081 
1082public:
1083  memoryaccess_def_iterator_base(T *Start) : Access(Start) {}
1084  memoryaccess_def_iterator_base() = default;
1085 
1086  bool operator==(const memoryaccess_def_iterator_base &Other) const {
1087    return Access == Other.Access && (!Access || ArgNo == Other.ArgNo);
1088  }
1089 
1090  // This is a bit ugly, but for MemoryPHI's, unlike PHINodes, you can't get the
1091  // block from the operand in constant time (In a PHINode, the uselist has
1092  // both, so it's just subtraction). We provide it as part of the
1093  // iterator to avoid callers having to linear walk to get the block.
1094  // If the operation becomes constant time on MemoryPHI's, this bit of
1095  // abstraction breaking should be removed.
1096  BasicBlock *getPhiArgBlock() const {
1097    MemoryPhi *MP = dyn_cast<MemoryPhi>(Access);
1098    assert(MP && "Tried to get phi arg block when not iterating over a PHI")((MP && "Tried to get phi arg block when not iterating over a PHI"
) ? static_cast<void> (0) : __assert_fail ("MP && \"Tried to get phi arg block when not iterating over a PHI\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 1098, __PRETTY_FUNCTION__));
1099    return MP->getIncomingBlock(ArgNo);
1100  }
1101 
1102  typename BaseT::iterator::pointer operator*() const {
1103    assert(Access && "Tried to access past the end of our iterator")((Access && "Tried to access past the end of our iterator"
) ? static_cast<void> (0) : __assert_fail ("Access && \"Tried to access past the end of our iterator\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 1103, __PRETTY_FUNCTION__));
1104    // Go to the first argument for phis, and the defining access for everything
1105    // else.
1106    if (const MemoryPhi *MP = dyn_cast<MemoryPhi>(Access))
1107      return MP->getIncomingValue(ArgNo);
1108    return cast<MemoryUseOrDef>(Access)->getDefiningAccess();
1109  }
1110 
1111  using BaseT::operator++;
1112  memoryaccess_def_iterator_base &operator++() {
1113    assert(Access && "Hit end of iterator")((Access && "Hit end of iterator") ? static_cast<void
> (0) : __assert_fail ("Access && \"Hit end of iterator\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 1113, __PRETTY_FUNCTION__));
1114    if (const MemoryPhi *MP = dyn_cast<MemoryPhi>(Access)) {
1115      if (++ArgNo >= MP->getNumIncomingValues()) {
1116        ArgNo = 0;
1117        Access = nullptr;
1118      }
1119    } else {
1120      Access = nullptr;
1121    }
1122    return *this;
1123  }
1124 
1125private:
1126  T *Access = nullptr;
1127  unsigned ArgNo = 0;
1128};
1129 
1130inline memoryaccess_def_iterator MemoryAccess::defs_begin() {
1131  return memoryaccess_def_iterator(this);
1132}
1133 
1134inline const_memoryaccess_def_iterator MemoryAccess::defs_begin() const {
1135  return const_memoryaccess_def_iterator(this);
1136}
1137 
1138inline memoryaccess_def_iterator MemoryAccess::defs_end() {
1139  return memoryaccess_def_iterator();
1140}
1141 
1142inline const_memoryaccess_def_iterator MemoryAccess::defs_end() const {
1143  return const_memoryaccess_def_iterator();
1144}
1145 
1146/// GraphTraits for a MemoryAccess, which walks defs in the normal case,
1147/// and uses in the inverse case.
1148template <> struct GraphTraits<MemoryAccess *> {
1149  using NodeRef = MemoryAccess *;
1150  using ChildIteratorType = memoryaccess_def_iterator;
1151 
1152  static NodeRef getEntryNode(NodeRef N) { return N; }
1153  static ChildIteratorType child_begin(NodeRef N) { return N->defs_begin(); }
1154  static ChildIteratorType child_end(NodeRef N) { return N->defs_end(); }
1155};
1156 
1157template <> struct GraphTraits<Inverse<MemoryAccess *>> {
1158  using NodeRef = MemoryAccess *;
1159  using ChildIteratorType = MemoryAccess::iterator;
1160 
1161  static NodeRef getEntryNode(NodeRef N) { return N; }
1162  static ChildIteratorType child_begin(NodeRef N) { return N->user_begin(); }
1163  static ChildIteratorType child_end(NodeRef N) { return N->user_end(); }
1164};
1165 
1166/// Provide an iterator that walks defs, giving both the memory access,
1167/// and the current pointer location, updating the pointer location as it
1168/// changes due to phi node translation.
1169///
1170/// This iterator, while somewhat specialized, is what most clients actually
1171/// want when walking upwards through MemorySSA def chains. It takes a pair of
1172/// <MemoryAccess,MemoryLocation>, and walks defs, properly translating the
1173/// memory location through phi nodes for the user.
1174class upward_defs_iterator
1175    : public iterator_facade_base<upward_defs_iterator,
1176                                  std::forward_iterator_tag,
1177                                  const MemoryAccessPair> {
1178  using BaseT = upward_defs_iterator::iterator_facade_base;
1179 
1180public:
1181  upward_defs_iterator(const MemoryAccessPair &Info, DominatorTree *DT,
1182                       bool *PerformedPhiTranslation = nullptr)
1183      : DefIterator(Info.first), Location(Info.second),
1184        OriginalAccess(Info.first), DT(DT),
1185        PerformedPhiTranslation(PerformedPhiTranslation) {
1186    CurrentPair.first = nullptr;
1187 
1188    WalkingPhi = Info.first && isa<MemoryPhi>(Info.first);
1189    fillInCurrentPair();
1190  }
1191 
1192  upward_defs_iterator() { CurrentPair.first = nullptr; }
1193 
1194  bool operator==(const upward_defs_iterator &Other) const {
1195    return DefIterator == Other.DefIterator;
1196  }
1197 
1198  BaseT::iterator::reference operator*() const {
1199    assert(DefIterator != OriginalAccess->defs_end() &&((DefIterator != OriginalAccess->defs_end() && "Tried to access past the end of our iterator"
) ? static_cast<void> (0) : __assert_fail ("DefIterator != OriginalAccess->defs_end() && \"Tried to access past the end of our iterator\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 1200, __PRETTY_FUNCTION__))
1200           "Tried to access past the end of our iterator")((DefIterator != OriginalAccess->defs_end() && "Tried to access past the end of our iterator"
) ? static_cast<void> (0) : __assert_fail ("DefIterator != OriginalAccess->defs_end() && \"Tried to access past the end of our iterator\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 1200, __PRETTY_FUNCTION__));
1201    return CurrentPair;
1202  }
1203 
1204  using BaseT::operator++;
1205  upward_defs_iterator &operator++() {
1206    assert(DefIterator != OriginalAccess->defs_end() &&((DefIterator != OriginalAccess->defs_end() && "Tried to access past the end of the iterator"
) ? static_cast<void> (0) : __assert_fail ("DefIterator != OriginalAccess->defs_end() && \"Tried to access past the end of the iterator\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 1207, __PRETTY_FUNCTION__))
1207           "Tried to access past the end of the iterator")((DefIterator != OriginalAccess->defs_end() && "Tried to access past the end of the iterator"
) ? static_cast<void> (0) : __assert_fail ("DefIterator != OriginalAccess->defs_end() && \"Tried to access past the end of the iterator\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 1207, __PRETTY_FUNCTION__));
1208    ++DefIterator;
1209    if (DefIterator != OriginalAccess->defs_end())
1210      fillInCurrentPair();
1211    return *this;
1212  }
1213 
1214  BasicBlock *getPhiArgBlock() const { return DefIterator.getPhiArgBlock(); }
1215 
1216private:
1217  /// Returns true if \p Ptr is guaranteed to be loop invariant for any possible
1218  /// loop. In particular, this guarantees that it only references a single
1219  /// MemoryLocation during execution of the containing function.
1220  bool IsGuaranteedLoopInvariant(Value *Ptr) const {
1221    auto IsGuaranteedLoopInvariantBase = [](Value *Ptr) {
1222      Ptr = Ptr->stripPointerCasts();
1223      if (!isa<Instruction>(Ptr))
1224        return true;
1225      return isa<AllocaInst>(Ptr);
1226    };
1227 
1228    Ptr = Ptr->stripPointerCasts();
1229    if (auto *GEP = dyn_cast<GEPOperator>(Ptr)) {
1230      return IsGuaranteedLoopInvariantBase(GEP->getPointerOperand()) &&
1231             GEP->hasAllConstantIndices();
1232    }
1233    return IsGuaranteedLoopInvariantBase(Ptr);
1234  }
1235 
1236  void fillInCurrentPair() {
1237    CurrentPair.first = *DefIterator;
1238    CurrentPair.second = Location;
1239    if (WalkingPhi && Location.Ptr) {
1240      // Mark size as unknown, if the location is not guaranteed to be
1241      // loop-invariant for any possible loop in the function. Setting the size
1242      // to unknown guarantees that any memory accesses that access locations
1243      // after the pointer are considered as clobbers, which is important to
1244      // catch loop carried dependences.
1245      if (Location.Ptr &&
1246          !IsGuaranteedLoopInvariant(const_cast<Value *>(Location.Ptr)))
1247        CurrentPair.second =
1248            Location.getWithNewSize(LocationSize::beforeOrAfterPointer());
1249      PHITransAddr Translator(
1250          const_cast<Value *>(Location.Ptr),
1251          OriginalAccess->getBlock()->getModule()->getDataLayout(), nullptr);
1252 
1253      if (!Translator.PHITranslateValue(OriginalAccess->getBlock(),
1254                                        DefIterator.getPhiArgBlock(), DT,
1255                                        true)) {
1256        Value *TransAddr = Translator.getAddr();
1257        if (TransAddr != Location.Ptr) {
1258          CurrentPair.second = CurrentPair.second.getWithNewPtr(TransAddr);
1259 
1260          if (TransAddr &&
1261              !IsGuaranteedLoopInvariant(const_cast<Value *>(TransAddr)))
1262            CurrentPair.second = CurrentPair.second.getWithNewSize(
1263                LocationSize::beforeOrAfterPointer());
1264 
1265          if (PerformedPhiTranslation)
1266            *PerformedPhiTranslation = true;
1267        }
1268      }
1269    }
1270  }
1271 
1272  MemoryAccessPair CurrentPair;
1273  memoryaccess_def_iterator DefIterator;
1274  MemoryLocation Location;
1275  MemoryAccess *OriginalAccess = nullptr;
1276  DominatorTree *DT = nullptr;
1277  bool WalkingPhi = false;
1278  bool *PerformedPhiTranslation = nullptr;
1279};
1280 
1281inline upward_defs_iterator
1282upward_defs_begin(const MemoryAccessPair &Pair, DominatorTree &DT,
1283                  bool *PerformedPhiTranslation = nullptr) {
1284  return upward_defs_iterator(Pair, &DT, PerformedPhiTranslation);
1285}
1286 
1287inline upward_defs_iterator upward_defs_end() { return upward_defs_iterator(); }
1288 
1289inline iterator_range<upward_defs_iterator>
1290upward_defs(const MemoryAccessPair &Pair, DominatorTree &DT) {
1291  return make_range(upward_defs_begin(Pair, DT), upward_defs_end());
1292}
1293 
1294/// Walks the defining accesses of MemoryDefs. Stops after we hit something that
1295/// has no defining use (e.g. a MemoryPhi or liveOnEntry). Note that, when
1296/// comparing against a null def_chain_iterator, this will compare equal only
1297/// after walking said Phi/liveOnEntry.
1298///
1299/// The UseOptimizedChain flag specifies whether to walk the clobbering
1300/// access chain, or all the accesses.
1301///
1302/// Normally, MemoryDef are all just def/use linked together, so a def_chain on
1303/// a MemoryDef will walk all MemoryDefs above it in the program until it hits
1304/// a phi node.  The optimized chain walks the clobbering access of a store.
1305/// So if you are just trying to find, given a store, what the next
1306/// thing that would clobber the same memory is, you want the optimized chain.
1307template <class T, bool UseOptimizedChain = false>
1308struct def_chain_iterator
1309    : public iterator_facade_base<def_chain_iterator<T, UseOptimizedChain>,
1310                                  std::forward_iterator_tag, MemoryAccess *> {
1311  def_chain_iterator() : MA(nullptr) {}
1312  def_chain_iterator(T MA) : MA(MA) {}
1313 
1314  T operator*() const { return MA; }
1315 
1316  def_chain_iterator &operator++() {
1317    // N.B. liveOnEntry has a null defining access.
1318    if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA)) {
1319      if (UseOptimizedChain && MUD->isOptimized())
1320        MA = MUD->getOptimized();
1321      else
1322        MA = MUD->getDefiningAccess();
1323    } else {
1324      MA = nullptr;
1325    }
1326 
1327    return *this;
1328  }
1329 
1330  bool operator==(const def_chain_iterator &O) const { return MA == O.MA; }
1331 
1332private:
1333  T MA;
1334};
1335 
1336template <class T>
1337inline iterator_range<def_chain_iterator<T>>
1338def_chain(T MA, MemoryAccess *UpTo = nullptr) {
1339#ifdef EXPENSIVE_CHECKS
1340  assert((!UpTo || find(def_chain(MA), UpTo) != def_chain_iterator<T>()) &&(((!UpTo || find(def_chain(MA), UpTo) != def_chain_iterator<
T>()) && "UpTo isn't in the def chain!") ? static_cast
<void> (0) : __assert_fail ("(!UpTo || find(def_chain(MA), UpTo) != def_chain_iterator<T>()) && \"UpTo isn't in the def chain!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 1341, __PRETTY_FUNCTION__))
1341         "UpTo isn't in the def chain!")(((!UpTo || find(def_chain(MA), UpTo) != def_chain_iterator<
T>()) && "UpTo isn't in the def chain!") ? static_cast
<void> (0) : __assert_fail ("(!UpTo || find(def_chain(MA), UpTo) != def_chain_iterator<T>()) && \"UpTo isn't in the def chain!\""
, "/build/llvm-toolchain-snapshot-12~++20201217111122+722247c8124/llvm/include/llvm/Analysis/MemorySSA.h"
, 1341, __PRETTY_FUNCTION__));
1342#endif
1343  return make_range(def_chain_iterator<T>(MA), def_chain_iterator<T>(UpTo));
1344}
1345 
1346template <class T>
1347inline iterator_range<def_chain_iterator<T, true>> optimized_def_chain(T MA) {
1348  return make_range(def_chain_iterator<T, true>(MA),
1349                    def_chain_iterator<T, true>(nullptr));
1350}
1351 
1352} // end namespace llvm
1353 
1354#endif // LLVM_ANALYSIS_MEMORYSSA_H