LLVM  10.0.0svn
Loads.cpp
Go to the documentation of this file.
1 //===- Loads.cpp - Local load analysis ------------------------------------===//
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 defines simple local analyses for load instructions.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "llvm/Analysis/Loads.h"
15 #include "llvm/Analysis/LoopInfo.h"
19 #include "llvm/IR/DataLayout.h"
20 #include "llvm/IR/GlobalAlias.h"
21 #include "llvm/IR/GlobalVariable.h"
22 #include "llvm/IR/IntrinsicInst.h"
23 #include "llvm/IR/LLVMContext.h"
24 #include "llvm/IR/Module.h"
25 #include "llvm/IR/Operator.h"
26 #include "llvm/IR/Statepoint.h"
27 
28 using namespace llvm;
29 
30 static MaybeAlign getBaseAlign(const Value *Base, const DataLayout &DL) {
31  if (const MaybeAlign PA = Base->getPointerAlignment(DL))
32  return *PA;
33  Type *const Ty = Base->getType()->getPointerElementType();
34  if (!Ty->isSized())
35  return None;
36  return Align(DL.getABITypeAlignment(Ty));
37 }
38 
39 static bool isAligned(const Value *Base, const APInt &Offset, Align Alignment,
40  const DataLayout &DL) {
41  if (MaybeAlign BA = getBaseAlign(Base, DL)) {
42  const APInt APBaseAlign(Offset.getBitWidth(), BA->value());
43  const APInt APAlign(Offset.getBitWidth(), Alignment.value());
44  assert(APAlign.isPowerOf2() && "must be a power of 2!");
45  return APBaseAlign.uge(APAlign) && !(Offset & (APAlign - 1));
46  }
47  return false;
48 }
49 
50 /// Test if V is always a pointer to allocated and suitably aligned memory for
51 /// a simple load or store.
53  const Value *V, Align Alignment, const APInt &Size, const DataLayout &DL,
54  const Instruction *CtxI, const DominatorTree *DT,
56  // Already visited? Bail out, we've likely hit unreachable code.
57  if (!Visited.insert(V).second)
58  return false;
59 
60  // Note that it is not safe to speculate into a malloc'd region because
61  // malloc may return null.
62 
63  // bitcast instructions are no-ops as far as dereferenceability is concerned.
64  if (const BitCastOperator *BC = dyn_cast<BitCastOperator>(V))
65  return isDereferenceableAndAlignedPointer(BC->getOperand(0), Alignment,
66  Size, DL, CtxI, DT, Visited);
67 
68  bool CheckForNonNull = false;
69  APInt KnownDerefBytes(Size.getBitWidth(),
70  V->getPointerDereferenceableBytes(DL, CheckForNonNull));
71  if (KnownDerefBytes.getBoolValue() && KnownDerefBytes.uge(Size))
72  if (!CheckForNonNull || isKnownNonZero(V, DL, 0, nullptr, CtxI, DT)) {
73  // As we recursed through GEPs to get here, we've incrementally checked
74  // that each step advanced by a multiple of the alignment. If our base is
75  // properly aligned, then the original offset accessed must also be.
76  Type *Ty = V->getType();
77  assert(Ty->isSized() && "must be sized");
78  APInt Offset(DL.getTypeStoreSizeInBits(Ty), 0);
79  return isAligned(V, Offset, Alignment, DL);
80  }
81 
82  // For GEPs, determine if the indexing lands within the allocated object.
83  if (const GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
84  const Value *Base = GEP->getPointerOperand();
85 
86  APInt Offset(DL.getIndexTypeSizeInBits(GEP->getType()), 0);
87  if (!GEP->accumulateConstantOffset(DL, Offset) || Offset.isNegative() ||
88  !Offset.urem(APInt(Offset.getBitWidth(), Alignment.value()))
89  .isMinValue())
90  return false;
91 
92  // If the base pointer is dereferenceable for Offset+Size bytes, then the
93  // GEP (== Base + Offset) is dereferenceable for Size bytes. If the base
94  // pointer is aligned to Align bytes, and the Offset is divisible by Align
95  // then the GEP (== Base + Offset == k_0 * Align + k_1 * Align) is also
96  // aligned to Align bytes.
97 
98  // Offset and Size may have different bit widths if we have visited an
99  // addrspacecast, so we can't do arithmetic directly on the APInt values.
101  Base, Alignment, Offset + Size.sextOrTrunc(Offset.getBitWidth()), DL,
102  CtxI, DT, Visited);
103  }
104 
105  // For gc.relocate, look through relocations
106  if (const GCRelocateInst *RelocateInst = dyn_cast<GCRelocateInst>(V))
108  RelocateInst->getDerivedPtr(), Alignment, Size, DL, CtxI, DT, Visited);
109 
110  if (const AddrSpaceCastInst *ASC = dyn_cast<AddrSpaceCastInst>(V))
111  return isDereferenceableAndAlignedPointer(ASC->getOperand(0), Alignment,
112  Size, DL, CtxI, DT, Visited);
113 
114  if (const auto *Call = dyn_cast<CallBase>(V))
115  if (auto *RP = getArgumentAliasingToReturnedPointer(Call, true))
116  return isDereferenceableAndAlignedPointer(RP, Alignment, Size, DL, CtxI,
117  DT, Visited);
118 
119  // If we don't know, assume the worst.
120  return false;
121 }
122 
124  const APInt &Size,
125  const DataLayout &DL,
126  const Instruction *CtxI,
127  const DominatorTree *DT) {
128  // Note: At the moment, Size can be zero. This ends up being interpreted as
129  // a query of whether [Base, V] is dereferenceable and V is aligned (since
130  // that's what the implementation happened to do). It's unclear if this is
131  // the desired semantic, but at least SelectionDAG does exercise this case.
132 
134  return ::isDereferenceableAndAlignedPointer(V, Alignment, Size, DL, CtxI, DT,
135  Visited);
136 }
137 
139  MaybeAlign MA,
140  const DataLayout &DL,
141  const Instruction *CtxI,
142  const DominatorTree *DT) {
143  if (!Ty->isSized())
144  return false;
145 
146  // When dereferenceability information is provided by a dereferenceable
147  // attribute, we know exactly how many bytes are dereferenceable. If we can
148  // determine the exact offset to the attributed variable, we can use that
149  // information here.
150 
151  // Require ABI alignment for loads without alignment specification
152  const Align Alignment = DL.getValueOrABITypeAlignment(MA, Ty);
153  APInt AccessSize(DL.getIndexTypeSizeInBits(V->getType()),
154  DL.getTypeStoreSize(Ty));
155  return isDereferenceableAndAlignedPointer(V, Alignment, AccessSize, DL, CtxI,
156  DT);
157 }
158 
160  const DataLayout &DL,
161  const Instruction *CtxI,
162  const DominatorTree *DT) {
163  return isDereferenceableAndAlignedPointer(V, Ty, Align::None(), DL, CtxI, DT);
164 }
165 
166 /// Test if A and B will obviously have the same value.
167 ///
168 /// This includes recognizing that %t0 and %t1 will have the same
169 /// value in code like this:
170 /// \code
171 /// %t0 = getelementptr \@a, 0, 3
172 /// store i32 0, i32* %t0
173 /// %t1 = getelementptr \@a, 0, 3
174 /// %t2 = load i32* %t1
175 /// \endcode
176 ///
177 static bool AreEquivalentAddressValues(const Value *A, const Value *B) {
178  // Test if the values are trivially equivalent.
179  if (A == B)
180  return true;
181 
182  // Test if the values come from identical arithmetic instructions.
183  // Use isIdenticalToWhenDefined instead of isIdenticalTo because
184  // this function is only used when one address use dominates the
185  // other, which means that they'll always either have the same
186  // value or one of them will have an undefined value.
187  if (isa<BinaryOperator>(A) || isa<CastInst>(A) || isa<PHINode>(A) ||
188  isa<GetElementPtrInst>(A))
189  if (const Instruction *BI = dyn_cast<Instruction>(B))
190  if (cast<Instruction>(A)->isIdenticalToWhenDefined(BI))
191  return true;
192 
193  // Otherwise they may not be equivalent.
194  return false;
195 }
196 
198  ScalarEvolution &SE,
199  DominatorTree &DT) {
200  auto &DL = LI->getModule()->getDataLayout();
201  Value *Ptr = LI->getPointerOperand();
202 
203  APInt EltSize(DL.getIndexTypeSizeInBits(Ptr->getType()),
204  DL.getTypeStoreSize(LI->getType()));
205  const Align Alignment = DL.getValueOrABITypeAlignment(
206  MaybeAlign(LI->getAlignment()), LI->getType());
207 
208  Instruction *HeaderFirstNonPHI = L->getHeader()->getFirstNonPHI();
209 
210  // If given a uniform (i.e. non-varying) address, see if we can prove the
211  // access is safe within the loop w/o needing predication.
212  if (L->isLoopInvariant(Ptr))
213  return isDereferenceableAndAlignedPointer(Ptr, Alignment, EltSize, DL,
214  HeaderFirstNonPHI, &DT);
215 
216  // Otherwise, check to see if we have a repeating access pattern where we can
217  // prove that all accesses are well aligned and dereferenceable.
218  auto *AddRec = dyn_cast<SCEVAddRecExpr>(SE.getSCEV(Ptr));
219  if (!AddRec || AddRec->getLoop() != L || !AddRec->isAffine())
220  return false;
221  auto* Step = dyn_cast<SCEVConstant>(AddRec->getStepRecurrence(SE));
222  if (!Step)
223  return false;
224  // TODO: generalize to access patterns which have gaps
225  if (Step->getAPInt() != EltSize)
226  return false;
227 
228  // TODO: If the symbolic trip count has a small bound (max count), we might
229  // be able to prove safety.
230  auto TC = SE.getSmallConstantTripCount(L);
231  if (!TC)
232  return false;
233 
234  const APInt AccessSize = TC * EltSize;
235 
236  auto *StartS = dyn_cast<SCEVUnknown>(AddRec->getStart());
237  if (!StartS)
238  return false;
239  assert(SE.isLoopInvariant(StartS, L) && "implied by addrec definition");
240  Value *Base = StartS->getValue();
241 
242  // For the moment, restrict ourselves to the case where the access size is a
243  // multiple of the requested alignment and the base is aligned.
244  // TODO: generalize if a case found which warrants
245  if (EltSize.urem(Alignment.value()) != 0)
246  return false;
247  return isDereferenceableAndAlignedPointer(Base, Alignment, AccessSize, DL,
248  HeaderFirstNonPHI, &DT);
249 }
250 
251 /// Check if executing a load of this pointer value cannot trap.
252 ///
253 /// If DT and ScanFrom are specified this method performs context-sensitive
254 /// analysis and returns true if it is safe to load immediately before ScanFrom.
255 ///
256 /// If it is not obviously safe to load from the specified pointer, we do
257 /// a quick local scan of the basic block containing \c ScanFrom, to determine
258 /// if the address is already accessed.
259 ///
260 /// This uses the pointee type to determine how many bytes need to be safe to
261 /// load from the pointer.
263  const DataLayout &DL,
264  Instruction *ScanFrom,
265  const DominatorTree *DT) {
266  // Zero alignment means that the load has the ABI alignment for the target
267  const Align Alignment =
269 
270  // If DT is not specified we can't make context-sensitive query
271  const Instruction* CtxI = DT ? ScanFrom : nullptr;
272  if (isDereferenceableAndAlignedPointer(V, Alignment, Size, DL, CtxI, DT))
273  return true;
274 
275  if (!ScanFrom)
276  return false;
277 
278  if (Size.getBitWidth() > 64)
279  return false;
280  const uint64_t LoadSize = Size.getZExtValue();
281 
282  // Otherwise, be a little bit aggressive by scanning the local block where we
283  // want to check to see if the pointer is already being loaded or stored
284  // from/to. If so, the previous load or store would have already trapped,
285  // so there is no harm doing an extra load (also, CSE will later eliminate
286  // the load entirely).
287  BasicBlock::iterator BBI = ScanFrom->getIterator(),
288  E = ScanFrom->getParent()->begin();
289 
290  // We can at least always strip pointer casts even though we can't use the
291  // base here.
292  V = V->stripPointerCasts();
293 
294  while (BBI != E) {
295  --BBI;
296 
297  // If we see a free or a call which may write to memory (i.e. which might do
298  // a free) the pointer could be marked invalid.
299  if (isa<CallInst>(BBI) && BBI->mayWriteToMemory() &&
300  !isa<DbgInfoIntrinsic>(BBI))
301  return false;
302 
303  Value *AccessedPtr;
304  MaybeAlign MaybeAccessedAlign;
305  if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
306  // Ignore volatile loads. The execution of a volatile load cannot
307  // be used to prove an address is backed by regular memory; it can,
308  // for example, point to an MMIO register.
309  if (LI->isVolatile())
310  continue;
311  AccessedPtr = LI->getPointerOperand();
312  MaybeAccessedAlign = MaybeAlign(LI->getAlignment());
313  } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) {
314  // Ignore volatile stores (see comment for loads).
315  if (SI->isVolatile())
316  continue;
317  AccessedPtr = SI->getPointerOperand();
318  MaybeAccessedAlign = MaybeAlign(SI->getAlignment());
319  } else
320  continue;
321 
322  Type *AccessedTy = AccessedPtr->getType()->getPointerElementType();
323 
324  const Align AccessedAlign =
325  DL.getValueOrABITypeAlignment(MaybeAccessedAlign, AccessedTy);
326  if (AccessedAlign < Alignment)
327  continue;
328 
329  // Handle trivial cases.
330  if (AccessedPtr == V &&
331  LoadSize <= DL.getTypeStoreSize(AccessedTy))
332  return true;
333 
334  if (AreEquivalentAddressValues(AccessedPtr->stripPointerCasts(), V) &&
335  LoadSize <= DL.getTypeStoreSize(AccessedTy))
336  return true;
337  }
338  return false;
339 }
340 
342  const DataLayout &DL,
343  Instruction *ScanFrom,
344  const DominatorTree *DT) {
346  return isSafeToLoadUnconditionally(V, Alignment, Size, DL, ScanFrom, DT);
347 }
348 
349  /// DefMaxInstsToScan - the default number of maximum instructions
350 /// to scan in the block, used by FindAvailableLoadedValue().
351 /// FindAvailableLoadedValue() was introduced in r60148, to improve jump
352 /// threading in part by eliminating partially redundant loads.
353 /// At that point, the value of MaxInstsToScan was already set to '6'
354 /// without documented explanation.
356 llvm::DefMaxInstsToScan("available-load-scan-limit", cl::init(6), cl::Hidden,
357  cl::desc("Use this to specify the default maximum number of instructions "
358  "to scan backward from a given instruction, when searching for "
359  "available loaded value"));
360 
362  BasicBlock *ScanBB,
363  BasicBlock::iterator &ScanFrom,
364  unsigned MaxInstsToScan,
365  AliasAnalysis *AA, bool *IsLoad,
366  unsigned *NumScanedInst) {
367  // Don't CSE load that is volatile or anything stronger than unordered.
368  if (!Load->isUnordered())
369  return nullptr;
370 
372  Load->getPointerOperand(), Load->getType(), Load->isAtomic(), ScanBB,
373  ScanFrom, MaxInstsToScan, AA, IsLoad, NumScanedInst);
374 }
375 
377  bool AtLeastAtomic, BasicBlock *ScanBB,
378  BasicBlock::iterator &ScanFrom,
379  unsigned MaxInstsToScan,
380  AliasAnalysis *AA, bool *IsLoadCSE,
381  unsigned *NumScanedInst) {
382  if (MaxInstsToScan == 0)
383  MaxInstsToScan = ~0U;
384 
385  const DataLayout &DL = ScanBB->getModule()->getDataLayout();
386 
387  // Try to get the store size for the type.
388  auto AccessSize = LocationSize::precise(DL.getTypeStoreSize(AccessTy));
389 
390  Value *StrippedPtr = Ptr->stripPointerCasts();
391 
392  while (ScanFrom != ScanBB->begin()) {
393  // We must ignore debug info directives when counting (otherwise they
394  // would affect codegen).
395  Instruction *Inst = &*--ScanFrom;
396  if (isa<DbgInfoIntrinsic>(Inst))
397  continue;
398 
399  // Restore ScanFrom to expected value in case next test succeeds
400  ScanFrom++;
401 
402  if (NumScanedInst)
403  ++(*NumScanedInst);
404 
405  // Don't scan huge blocks.
406  if (MaxInstsToScan-- == 0)
407  return nullptr;
408 
409  --ScanFrom;
410  // If this is a load of Ptr, the loaded value is available.
411  // (This is true even if the load is volatile or atomic, although
412  // those cases are unlikely.)
413  if (LoadInst *LI = dyn_cast<LoadInst>(Inst))
415  LI->getPointerOperand()->stripPointerCasts(), StrippedPtr) &&
416  CastInst::isBitOrNoopPointerCastable(LI->getType(), AccessTy, DL)) {
417 
418  // We can value forward from an atomic to a non-atomic, but not the
419  // other way around.
420  if (LI->isAtomic() < AtLeastAtomic)
421  return nullptr;
422 
423  if (IsLoadCSE)
424  *IsLoadCSE = true;
425  return LI;
426  }
427 
428  if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
429  Value *StorePtr = SI->getPointerOperand()->stripPointerCasts();
430  // If this is a store through Ptr, the value is available!
431  // (This is true even if the store is volatile or atomic, although
432  // those cases are unlikely.)
433  if (AreEquivalentAddressValues(StorePtr, StrippedPtr) &&
434  CastInst::isBitOrNoopPointerCastable(SI->getValueOperand()->getType(),
435  AccessTy, DL)) {
436 
437  // We can value forward from an atomic to a non-atomic, but not the
438  // other way around.
439  if (SI->isAtomic() < AtLeastAtomic)
440  return nullptr;
441 
442  if (IsLoadCSE)
443  *IsLoadCSE = false;
444  return SI->getOperand(0);
445  }
446 
447  // If both StrippedPtr and StorePtr reach all the way to an alloca or
448  // global and they are different, ignore the store. This is a trivial form
449  // of alias analysis that is important for reg2mem'd code.
450  if ((isa<AllocaInst>(StrippedPtr) || isa<GlobalVariable>(StrippedPtr)) &&
451  (isa<AllocaInst>(StorePtr) || isa<GlobalVariable>(StorePtr)) &&
452  StrippedPtr != StorePtr)
453  continue;
454 
455  // If we have alias analysis and it says the store won't modify the loaded
456  // value, ignore the store.
457  if (AA && !isModSet(AA->getModRefInfo(SI, StrippedPtr, AccessSize)))
458  continue;
459 
460  // Otherwise the store that may or may not alias the pointer, bail out.
461  ++ScanFrom;
462  return nullptr;
463  }
464 
465  // If this is some other instruction that may clobber Ptr, bail out.
466  if (Inst->mayWriteToMemory()) {
467  // If alias analysis claims that it really won't modify the load,
468  // ignore it.
469  if (AA && !isModSet(AA->getModRefInfo(Inst, StrippedPtr, AccessSize)))
470  continue;
471 
472  // May modify the pointer, bail out.
473  ++ScanFrom;
474  return nullptr;
475  }
476  }
477 
478  // Got to the start of the block, we didn't find it, but are done for this
479  // block.
480  return nullptr;
481 }
const NoneType None
Definition: None.h:23
unsigned getSmallConstantTripCount(const Loop *L)
Returns the maximum trip count of the loop if it is a single-exit loop and we can compute a small max...
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:111
constexpr char Align[]
Key for Kernel::Arg::Metadata::mAlign.
uint64_t getZExtValue() const
Get zero extended value.
Definition: APInt.h:1571
This class represents lattice values for constants.
Definition: AllocatorList.h:23
bool isSafeToLoadUnconditionally(Value *V, MaybeAlign Alignment, APInt &Size, const DataLayout &DL, Instruction *ScanFrom=nullptr, const DominatorTree *DT=nullptr)
Return true if we know that executing a load from this value cannot trap.
Definition: Loads.cpp:262
bool isAtomic() const
Return true if this instruction has an AtomicOrdering of unordered or higher.
bool isSized(SmallPtrSetImpl< Type *> *Visited=nullptr) const
Return true if it makes sense to take the size of this type.
Definition: Type.h:265
The main scalar evolution driver.
cl::opt< unsigned > DefMaxInstsToScan
The default number of maximum instructions to scan in the block, used by FindAvailableLoadedValue().
bool mayWriteToMemory() const
Return true if this instruction may modify memory.
bool isDereferenceableAndAlignedPointer(const Value *V, Type *Ty, MaybeAlign Alignment, const DataLayout &DL, const Instruction *CtxI=nullptr, const DominatorTree *DT=nullptr)
Returns true if V is always a dereferenceable pointer with alignment greater or equal than requested...
Definition: Loads.cpp:138
static LocationSize precise(uint64_t Value)
bool isLoopInvariant(const SCEV *S, const Loop *L)
Return true if the value of the given SCEV is unchanging in the specified loop.
Value * FindAvailablePtrLoadStore(Value *Ptr, Type *AccessTy, bool AtLeastAtomic, BasicBlock *ScanBB, BasicBlock::iterator &ScanFrom, unsigned MaxInstsToScan, AliasAnalysis *AA, bool *IsLoad, unsigned *NumScanedInst)
Scan backwards to see if we have the value of the given pointer available locally within a small numb...
Definition: Loads.cpp:376
An instruction for reading from memory.
Definition: Instructions.h:169
Hexagon Common GEP
unsigned getBitWidth() const
Return the number of bits in the APInt.
Definition: APInt.h:1517
static bool isBitOrNoopPointerCastable(Type *SrcTy, Type *DestTy, const DataLayout &DL)
Check whether a bitcast, inttoptr, or ptrtoint cast between these types is valid and a no-op...
iterator begin()
Instruction iterator methods.
Definition: BasicBlock.h:273
const Module * getModule() const
Return the module owning the function this basic block belongs to, or nullptr if the function does no...
Definition: BasicBlock.cpp:140
This class represents a conversion between pointers from one address space to another.
Type * getPointerElementType() const
Definition: Type.h:381
const DataLayout & getDataLayout() const
Get the data layout for the module&#39;s target platform.
Definition: Module.cpp:369
Value * FindAvailableLoadedValue(LoadInst *Load, BasicBlock *ScanBB, BasicBlock::iterator &ScanFrom, unsigned MaxInstsToScan=DefMaxInstsToScan, AliasAnalysis *AA=nullptr, bool *IsLoadCSE=nullptr, unsigned *NumScanedInst=nullptr)
Scan backwards to see if we have the value of the given load available locally within a small number ...
Definition: Loads.cpp:361
BlockT * getHeader() const
Definition: LoopInfo.h:105
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:246
This node represents a polynomial recurrence on the trip count of the specified loop.
TypeSize getTypeStoreSize(Type *Ty) const
Returns the maximum number of bytes that may be overwritten by storing the specified type...
Definition: DataLayout.h:454
APInt sextOrTrunc(unsigned width) const
Sign extend or truncate to width.
Definition: APInt.cpp:938
An instruction for storing to memory.
Definition: Instructions.h:325
Align getValueOrABITypeAlignment(MaybeAlign Alignment, Type *Ty) const
Helper function to return Alignment if it&#39;s set or the result of getABITypeAlignment(Ty), in any case the result is a valid alignment.
Definition: DataLayout.h:508
uint64_t value() const
This is a hole in the type system and should not be abused.
Definition: Alignment.h:86
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:144
bool isNegative() const
Determine sign of this APInt.
Definition: APInt.h:363
This means that we are dealing with an entirely unknown SCEV value, and only represent it as its LLVM...
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:432
const Instruction * getFirstNonPHI() const
Returns a pointer to the first instruction in this block that is not a PHINode instruction.
Definition: BasicBlock.cpp:196
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
APInt urem(const APInt &RHS) const
Unsigned remainder operation.
Definition: APInt.cpp:1669
LLVM Basic Block Representation.
Definition: BasicBlock.h:57
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
std::pair< iterator, bool > insert(PtrType Ptr)
Inserts Ptr if and only if there is no element in the container equal to Ptr.
Definition: SmallPtrSet.h:370
MaybeAlign getPointerAlignment(const DataLayout &DL) const
Returns an alignment of the pointer value.
Definition: Value.cpp:674
bool isUnordered() const
Definition: Instructions.h:283
Value * getPointerOperand()
Definition: Instructions.h:289
self_iterator getIterator()
Definition: ilist_node.h:81
unsigned getIndexTypeSizeInBits(Type *Ty) const
Layout size of the index used in GEP calculation.
Definition: DataLayout.cpp:687
static constexpr const Align None()
Returns a default constructed Align which corresponds to no alignment.
Definition: Alignment.h:93
const Value * stripPointerCasts() const
Strip off pointer casts, all-zero GEPs and address space casts.
Definition: Value.cpp:529
This struct is a compact representation of a valid (non-zero power of two) alignment.
Definition: Alignment.h:40
bool isLoopInvariant(const Value *V) const
Return true if the specified value is loop invariant.
Definition: LoopInfo.cpp:61
SmallPtrSet - This class implements a set which is optimized for holding SmallSize or less elements...
Definition: SmallPtrSet.h:417
const Value * getArgumentAliasingToReturnedPointer(const CallBase *Call, bool MustPreserveNullness)
This function returns call pointer argument that is considered the same by aliasing rules...
bool isDereferenceablePointer(const Value *V, Type *Ty, const DataLayout &DL, const Instruction *CtxI=nullptr, const DominatorTree *DT=nullptr)
Return true if this is always a dereferenceable pointer.
Definition: Loads.cpp:159
This struct is a compact representation of a valid (power of two) or undefined (0) alignment...
Definition: Alignment.h:117
Module.h This file contains the declarations for the Module class.
unsigned getABITypeAlignment(Type *Ty) const
Returns the minimum ABI-required alignment for the specified type.
Definition: DataLayout.cpp:755
uint64_t getPointerDereferenceableBytes(const DataLayout &DL, bool &CanBeNull) const
Returns the number of bytes known to be dereferenceable for the pointer value.
Definition: Value.cpp:608
bool isAligned(Align Lhs, uint64_t SizeInBytes)
Checks that SizeInBytes is a multiple of the alignment.
Definition: Alignment.h:146
static bool AreEquivalentAddressValues(const Value *A, const Value *B)
Test if A and B will obviously have the same value.
Definition: Loads.cpp:177
const Module * getModule() const
Return the module owning the function this instruction belongs to or nullptr it the function does not...
Definition: Instruction.cpp:55
Class for arbitrary precision integers.
Definition: APInt.h:69
bool isKnownNonZero(const Value *V, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, bool UseInstrInfo=true)
Return true if the given value is known to be non-zero when defined.
InstListType::iterator iterator
Instruction iterators...
Definition: BasicBlock.h:89
bool isDereferenceableAndAlignedInLoop(LoadInst *LI, Loop *L, ScalarEvolution &SE, DominatorTree &DT)
Return true if we can prove that the given load (which is assumed to be within the specified loop) wo...
Definition: Loads.cpp:197
LLVM_NODISCARD bool isModSet(const ModRefInfo MRI)
unsigned getAlignment() const
Return the alignment of the access that is being performed.
Definition: Instructions.h:242
Represents a single loop in the control flow graph.
Definition: LoopInfo.h:509
static GCRegistry::Add< ErlangGC > A("erlang", "erlang-compatible garbage collector")
static bool isDereferenceableAndAlignedPointer(const Value *V, Align Alignment, const APInt &Size, const DataLayout &DL, const Instruction *CtxI, const DominatorTree *DT, SmallPtrSetImpl< const Value *> &Visited)
Test if V is always a pointer to allocated and suitably aligned memory for a simple load or store...
Definition: Loads.cpp:52
LLVM_NODISCARD std::enable_if<!is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type >::type dyn_cast(const Y &Val)
Definition: Casting.h:332
uint32_t Size
Definition: Profile.cpp:46
bool isMinValue() const
Determine if this is the smallest unsigned value.
Definition: APInt.h:436
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
Represents calls to the gc.relocate intrinsic.
Definition: Statepoint.h:360
LLVM Value Representation.
Definition: Value.h:74
const SCEV * getSCEV(Value *V)
Return a SCEV expression for the full generality of the specified expression.
static MaybeAlign getBaseAlign(const Value *Base, const DataLayout &DL)
Definition: Loads.cpp:30
ModRefInfo getModRefInfo(const CallBase *Call, const MemoryLocation &Loc)
getModRefInfo (for call sites) - Return information about whether a particular call site modifies or ...
const BasicBlock * getParent() const
Definition: Instruction.h:66
This class represents a constant integer value.