/// are lifetime markers.
bool onlyUsedByLifetimeMarkers(const Value *V);
+ /// isDereferenceablePointer - Return true if this is always a dereferenceable
+ /// pointer.
+ ///
+ /// Test if this value is always a pointer to allocated and suitably aligned
+ /// memory for a simple load or store.
+ bool isDereferenceablePointer(const Value *V, const DataLayout &DL);
+
/// isSafeToSpeculativelyExecute - Return true if the instruction does not
/// have any effects besides calculating the result and does not have
/// undefined behavior.
return const_cast<Value*>(this)->stripInBoundsOffsets();
}
- /// \brief Check if this is always a dereferenceable pointer.
- ///
- /// Test if this value is always a pointer to allocated and suitably aligned
- /// memory for a simple load or store.
- bool isDereferenceablePointer(const DataLayout &DL) const;
-
/// \brief Translate PHI node to its predecessor from the given basic block.
///
/// If this value is a PHI node with CurBB as its parent, return the value in
#include "llvm/Analysis/Passes.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/Analysis/MemoryDependenceAnalysis.h"
+#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/InstIterator.h"
for (auto &I: inst_range(F)) {
if (LoadInst *LI = dyn_cast<LoadInst>(&I)) {
Value *PO = LI->getPointerOperand();
- if (PO->isDereferenceablePointer(DL))
+ if (isDereferenceablePointer(PO, DL))
Vec.push_back(PO);
}
}
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/PatternMatch.h"
+#include "llvm/IR/Statepoint.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#include <cstring>
return true;
}
+static bool isDereferenceableFromAttribute(const Value *BV, APInt Offset,
+ Type *Ty, const DataLayout &DL) {
+ assert(Offset.isNonNegative() && "offset can't be negative");
+ assert(Ty->isSized() && "must be sized");
+
+ APInt DerefBytes(Offset.getBitWidth(), 0);
+ if (const Argument *A = dyn_cast<Argument>(BV)) {
+ DerefBytes = A->getDereferenceableBytes();
+ } else if (auto CS = ImmutableCallSite(BV)) {
+ DerefBytes = CS.getDereferenceableBytes(0);
+ }
+
+ if (DerefBytes.getBoolValue())
+ if (DerefBytes.uge(Offset + DL.getTypeStoreSize(Ty)))
+ return true;
+
+ return false;
+}
+
+static bool isDereferenceableFromAttribute(const Value *V,
+ const DataLayout &DL) {
+ Type *VTy = V->getType();
+ Type *Ty = VTy->getPointerElementType();
+ if (!Ty->isSized())
+ return false;
+
+ APInt Offset(DL.getTypeStoreSizeInBits(VTy), 0);
+ return isDereferenceableFromAttribute(V, Offset, Ty, DL);
+}
+
+/// Return true if Value is always a dereferenceable pointer.
+///
+/// Test if V is always a pointer to allocated and suitably aligned memory for
+/// a simple load or store.
+static bool isDereferenceablePointer(const Value *V, const DataLayout &DL,
+ SmallPtrSetImpl<const Value *> &Visited) {
+ // Note that it is not safe to speculate into a malloc'd region because
+ // malloc may return null.
+
+ // These are obviously ok.
+ if (isa<AllocaInst>(V)) return true;
+
+ // It's not always safe to follow a bitcast, for example:
+ // bitcast i8* (alloca i8) to i32*
+ // would result in a 4-byte load from a 1-byte alloca. However,
+ // if we're casting from a pointer from a type of larger size
+ // to a type of smaller size (or the same size), and the alignment
+ // is at least as large as for the resulting pointer type, then
+ // we can look through the bitcast.
+ if (const BitCastOperator *BC = dyn_cast<BitCastOperator>(V)) {
+ Type *STy = BC->getSrcTy()->getPointerElementType(),
+ *DTy = BC->getDestTy()->getPointerElementType();
+ if (STy->isSized() && DTy->isSized() &&
+ (DL.getTypeStoreSize(STy) >= DL.getTypeStoreSize(DTy)) &&
+ (DL.getABITypeAlignment(STy) >= DL.getABITypeAlignment(DTy)))
+ return isDereferenceablePointer(BC->getOperand(0), DL, Visited);
+ }
+
+ // Global variables which can't collapse to null are ok.
+ if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
+ return !GV->hasExternalWeakLinkage();
+
+ // byval arguments are okay.
+ if (const Argument *A = dyn_cast<Argument>(V))
+ if (A->hasByValAttr())
+ return true;
+
+ if (isDereferenceableFromAttribute(V, DL))
+ return true;
+
+ // For GEPs, determine if the indexing lands within the allocated object.
+ if (const GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
+ // Conservatively require that the base pointer be fully dereferenceable.
+ if (!Visited.insert(GEP->getOperand(0)).second)
+ return false;
+ if (!isDereferenceablePointer(GEP->getOperand(0), DL, Visited))
+ return false;
+ // Check the indices.
+ gep_type_iterator GTI = gep_type_begin(GEP);
+ for (User::const_op_iterator I = GEP->op_begin()+1,
+ E = GEP->op_end(); I != E; ++I) {
+ Value *Index = *I;
+ Type *Ty = *GTI++;
+ // Struct indices can't be out of bounds.
+ if (isa<StructType>(Ty))
+ continue;
+ ConstantInt *CI = dyn_cast<ConstantInt>(Index);
+ if (!CI)
+ return false;
+ // Zero is always ok.
+ if (CI->isZero())
+ continue;
+ // Check to see that it's within the bounds of an array.
+ ArrayType *ATy = dyn_cast<ArrayType>(Ty);
+ if (!ATy)
+ return false;
+ if (CI->getValue().getActiveBits() > 64)
+ return false;
+ if (CI->getZExtValue() >= ATy->getNumElements())
+ return false;
+ }
+ // Indices check out; this is dereferenceable.
+ return true;
+ }
+
+ // For gc.relocate, look through relocations
+ if (const IntrinsicInst *I = dyn_cast<IntrinsicInst>(V))
+ if (I->getIntrinsicID() == Intrinsic::experimental_gc_relocate) {
+ GCRelocateOperands RelocateInst(I);
+ return isDereferenceablePointer(RelocateInst.derivedPtr(), DL, Visited);
+ }
+
+ if (const AddrSpaceCastInst *ASC = dyn_cast<AddrSpaceCastInst>(V))
+ return isDereferenceablePointer(ASC->getOperand(0), DL, Visited);
+
+ // If we don't know, assume the worst.
+ return false;
+}
+
+bool llvm::isDereferenceablePointer(const Value *V, const DataLayout &DL) {
+ // When dereferenceability information is provided by a dereferenceable
+ // attribute, we know exactly how many bytes are dereferenceable. If we can
+ // determine the exact offset to the attributed variable, we can use that
+ // information here.
+ Type *VTy = V->getType();
+ Type *Ty = VTy->getPointerElementType();
+ if (Ty->isSized()) {
+ APInt Offset(DL.getTypeStoreSizeInBits(VTy), 0);
+ const Value *BV = V->stripAndAccumulateInBoundsConstantOffsets(DL, Offset);
+
+ if (Offset.isNonNegative())
+ if (isDereferenceableFromAttribute(BV, Offset, Ty, DL))
+ return true;
+ }
+
+ SmallPtrSet<const Value *, 32> Visited;
+ return ::isDereferenceablePointer(V, DL, Visited);
+}
+
bool llvm::isSafeToSpeculativelyExecute(const Value *V) {
const Operator *Inst = dyn_cast<Operator>(V);
if (!Inst)
LI->getParent()->getParent()->hasFnAttribute(Attribute::SanitizeThread))
return false;
const DataLayout &DL = LI->getModule()->getDataLayout();
- return LI->getPointerOperand()->isDereferenceablePointer(DL);
+ return isDereferenceablePointer(LI->getPointerOperand(), DL);
}
case Instruction::Call: {
if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
return stripPointerCastsAndOffsets<PSK_InBounds>(this);
}
-/// \brief Check if Value is always a dereferenceable pointer.
-///
-/// Test if V is always a pointer to allocated and suitably aligned memory for
-/// a simple load or store.
-static bool isDereferenceablePointer(const Value *V, const DataLayout &DL,
- SmallPtrSetImpl<const Value *> &Visited) {
- // Note that it is not safe to speculate into a malloc'd region because
- // malloc may return null.
-
- // These are obviously ok.
- if (isa<AllocaInst>(V)) return true;
-
- // It's not always safe to follow a bitcast, for example:
- // bitcast i8* (alloca i8) to i32*
- // would result in a 4-byte load from a 1-byte alloca. However,
- // if we're casting from a pointer from a type of larger size
- // to a type of smaller size (or the same size), and the alignment
- // is at least as large as for the resulting pointer type, then
- // we can look through the bitcast.
- if (const BitCastOperator *BC = dyn_cast<BitCastOperator>(V)) {
- Type *STy = BC->getSrcTy()->getPointerElementType(),
- *DTy = BC->getDestTy()->getPointerElementType();
- if (STy->isSized() && DTy->isSized() &&
- (DL.getTypeStoreSize(STy) >= DL.getTypeStoreSize(DTy)) &&
- (DL.getABITypeAlignment(STy) >= DL.getABITypeAlignment(DTy)))
- return isDereferenceablePointer(BC->getOperand(0), DL, Visited);
- }
-
- // Global variables which can't collapse to null are ok.
- if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
- return !GV->hasExternalWeakLinkage();
-
- // byval arguments are okay. Arguments specifically marked as
- // dereferenceable are okay too.
- if (const Argument *A = dyn_cast<Argument>(V)) {
- if (A->hasByValAttr())
- return true;
- else if (uint64_t Bytes = A->getDereferenceableBytes()) {
- Type *Ty = V->getType()->getPointerElementType();
- if (Ty->isSized() && DL.getTypeStoreSize(Ty) <= Bytes)
- return true;
- }
-
- return false;
- }
-
- // Return values from call sites specifically marked as dereferenceable are
- // also okay.
- if (auto CS = ImmutableCallSite(V)) {
- if (uint64_t Bytes = CS.getDereferenceableBytes(0)) {
- Type *Ty = V->getType()->getPointerElementType();
- if (Ty->isSized() && DL.getTypeStoreSize(Ty) <= Bytes)
- return true;
- }
- }
-
- // For GEPs, determine if the indexing lands within the allocated object.
- if (const GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
- // Conservatively require that the base pointer be fully dereferenceable.
- if (!Visited.insert(GEP->getOperand(0)).second)
- return false;
- if (!isDereferenceablePointer(GEP->getOperand(0), DL, Visited))
- return false;
- // Check the indices.
- gep_type_iterator GTI = gep_type_begin(GEP);
- for (User::const_op_iterator I = GEP->op_begin()+1,
- E = GEP->op_end(); I != E; ++I) {
- Value *Index = *I;
- Type *Ty = *GTI++;
- // Struct indices can't be out of bounds.
- if (isa<StructType>(Ty))
- continue;
- ConstantInt *CI = dyn_cast<ConstantInt>(Index);
- if (!CI)
- return false;
- // Zero is always ok.
- if (CI->isZero())
- continue;
- // Check to see that it's within the bounds of an array.
- ArrayType *ATy = dyn_cast<ArrayType>(Ty);
- if (!ATy)
- return false;
- if (CI->getValue().getActiveBits() > 64)
- return false;
- if (CI->getZExtValue() >= ATy->getNumElements())
- return false;
- }
- // Indices check out; this is dereferenceable.
- return true;
- }
-
- // For gc.relocate, look through relocations
- if (const IntrinsicInst *I = dyn_cast<IntrinsicInst>(V))
- if (I->getIntrinsicID() == Intrinsic::experimental_gc_relocate) {
- GCRelocateOperands RelocateInst(I);
- return isDereferenceablePointer(RelocateInst.derivedPtr(), DL, Visited);
- }
-
- if (const AddrSpaceCastInst *ASC = dyn_cast<AddrSpaceCastInst>(V))
- return isDereferenceablePointer(ASC->getOperand(0), DL, Visited);
-
- // If we don't know, assume the worst.
- return false;
-}
-
-bool Value::isDereferenceablePointer(const DataLayout &DL) const {
- // When dereferenceability information is provided by a dereferenceable
- // attribute, we know exactly how many bytes are dereferenceable. If we can
- // determine the exact offset to the attributed variable, we can use that
- // information here.
- Type *Ty = getType()->getPointerElementType();
- if (Ty->isSized()) {
- APInt Offset(DL.getTypeStoreSizeInBits(getType()), 0);
- const Value *BV = stripAndAccumulateInBoundsConstantOffsets(DL, Offset);
-
- APInt DerefBytes(Offset.getBitWidth(), 0);
- if (const Argument *A = dyn_cast<Argument>(BV))
- DerefBytes = A->getDereferenceableBytes();
- else if (auto CS = ImmutableCallSite(BV))
- DerefBytes = CS.getDereferenceableBytes(0);
-
- if (DerefBytes.getBoolValue() && Offset.isNonNegative()) {
- if (DerefBytes.uge(Offset + DL.getTypeStoreSize(Ty)))
- return true;
- }
- }
-
- SmallPtrSet<const Value *, 32> Visited;
- return ::isDereferenceablePointer(this, DL, Visited);
-}
-
Value *Value::DoPHITranslation(const BasicBlock *CurBB,
const BasicBlock *PredBB) {
PHINode *PN = dyn_cast<PHINode>(this);
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/CallGraph.h"
#include "llvm/Analysis/CallGraphSCCPass.h"
+#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Constants.h"
CallSite CS(U);
assert(CS && "Should only have direct calls!");
- if (!CS.getArgument(ArgNo)->isDereferenceablePointer(DL))
+ if (!isDereferenceablePointer(CS.getArgument(ArgNo), DL))
return false;
}
return true;
II->addAttribute(AttributeSet::ReturnIndex, Attribute::NonNull);
// isDereferenceablePointer -> deref attribute
- if (DerivedPtr->isDereferenceablePointer(DL)) {
+ if (isDereferenceablePointer(DerivedPtr, DL)) {
if (Argument *A = dyn_cast<Argument>(DerivedPtr)) {
uint64_t Bytes = A->getDereferenceableBytes();
II->addDereferenceableAttr(AttributeSet::ReturnIndex, Bytes);
// If this pointer is always safe to load, or if we can prove that there
// is already a load in the block, then we can move the load to the pred
// block.
- if (InVal->isDereferenceablePointer(DL) ||
+ if (isDereferenceablePointer(InVal, DL) ||
isSafeToLoadUnconditionally(InVal, TI, MaxAlign))
continue;
Value *TValue = SI.getTrueValue();
Value *FValue = SI.getFalseValue();
const DataLayout &DL = SI.getModule()->getDataLayout();
- bool TDerefable = TValue->isDereferenceablePointer(DL);
- bool FDerefable = FValue->isDereferenceablePointer(DL);
+ bool TDerefable = isDereferenceablePointer(TValue, DL);
+ bool FDerefable = isDereferenceablePointer(FValue, DL);
for (User *U : SI.users()) {
LoadInst *LI = dyn_cast<LoadInst>(U);
/// the select can be loaded unconditionally.
static bool isSafeSelectToSpeculate(SelectInst *SI) {
const DataLayout &DL = SI->getModule()->getDataLayout();
- bool TDerefable = SI->getTrueValue()->isDereferenceablePointer(DL);
- bool FDerefable = SI->getFalseValue()->isDereferenceablePointer(DL);
+ bool TDerefable = isDereferenceablePointer(SI->getTrueValue(), DL);
+ bool FDerefable = isDereferenceablePointer(SI->getFalseValue(), DL);
for (User *U : SI->users()) {
LoadInst *LI = dyn_cast<LoadInst>(U);
// If this pointer is always safe to load, or if we can prove that there is
// already a load in the block, then we can move the load to the pred block.
- if (InVal->isDereferenceablePointer(DL) ||
+ if (isDereferenceablePointer(InVal, DL) ||
isSafeToLoadUnconditionally(InVal, Pred->getTerminator(), MaxAlign))
continue;
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