-//===- BasicAliasAnalysis.cpp - Local Alias Analysis Impl -----------------===//
+//===- BasicAliasAnalysis.cpp - Stateless Alias Analysis Impl -------------===//
//
// The LLVM Compiler Infrastructure
//
//
//===----------------------------------------------------------------------===//
//
-// This file defines the default implementation of the Alias Analysis interface
-// that simply implements a few identities (two different globals cannot alias,
-// etc), but otherwise does no analysis.
+// This file defines the primary stateless implementation of the
+// Alias Analysis interface that implements identities (two different
+// globals cannot alias, etc), but does no stateful analysis.
//
//===----------------------------------------------------------------------===//
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
+#include "llvm/GlobalAlias.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Instructions.h"
#include "llvm/IntrinsicInst.h"
+#include "llvm/LLVMContext.h"
#include "llvm/Operator.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/CaptureTracking.h"
#include "llvm/Analysis/MemoryBuiltins.h"
+#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Target/TargetData.h"
#include "llvm/ADT/SmallPtrSet.h"
/// isObjectSmallerThan - Return true if we can prove that the object specified
/// by V is smaller than Size.
-static bool isObjectSmallerThan(const Value *V, unsigned Size,
+static bool isObjectSmallerThan(const Value *V, uint64_t Size,
const TargetData &TD) {
const Type *AccessTy;
if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
}
//===----------------------------------------------------------------------===//
-// NoAA Pass
+// GetElementPtr Instruction Decomposition and Analysis
//===----------------------------------------------------------------------===//
namespace {
- /// NoAA - This class implements the -no-aa pass, which always returns "I
- /// don't know" for alias queries. NoAA is unlike other alias analysis
- /// implementations, in that it does not chain to a previous analysis. As
- /// such it doesn't follow many of the rules that other alias analyses must.
- ///
- struct NoAA : public ImmutablePass, public AliasAnalysis {
- static char ID; // Class identification, replacement for typeinfo
- NoAA() : ImmutablePass(ID) {}
- explicit NoAA(char &PID) : ImmutablePass(PID) { }
-
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- }
-
- virtual void initializePass() {
- TD = getAnalysisIfAvailable<TargetData>();
- }
-
- virtual AliasResult alias(const Value *V1, unsigned V1Size,
- const Value *V2, unsigned V2Size) {
- return MayAlias;
- }
-
- virtual ModRefBehavior getModRefBehavior(ImmutableCallSite CS) {
- return UnknownModRefBehavior;
- }
- virtual ModRefBehavior getModRefBehavior(const Function *F) {
- return UnknownModRefBehavior;
- }
-
- virtual bool pointsToConstantMemory(const Value *P) { return false; }
- virtual ModRefResult getModRefInfo(ImmutableCallSite CS,
- const Value *P, unsigned Size) {
- return ModRef;
- }
- virtual ModRefResult getModRefInfo(ImmutableCallSite CS1,
- ImmutableCallSite CS2) {
- return ModRef;
- }
-
- virtual void deleteValue(Value *V) {}
- virtual void copyValue(Value *From, Value *To) {}
-
- /// getAdjustedAnalysisPointer - This method is used when a pass implements
- /// an analysis interface through multiple inheritance. If needed, it
- /// should override this to adjust the this pointer as needed for the
- /// specified pass info.
- virtual void *getAdjustedAnalysisPointer(const void *ID) {
- if (ID == &AliasAnalysis::ID)
- return (AliasAnalysis*)this;
- return this;
- }
+ enum ExtensionKind {
+ EK_NotExtended,
+ EK_SignExt,
+ EK_ZeroExt
};
-} // End of anonymous namespace
-
-// Register this pass...
-char NoAA::ID = 0;
-INITIALIZE_AG_PASS(NoAA, AliasAnalysis, "no-aa",
- "No Alias Analysis (always returns 'may' alias)",
- true, true, false);
-
-ImmutablePass *llvm::createNoAAPass() { return new NoAA(); }
-
-//===----------------------------------------------------------------------===//
-// GetElementPtr Instruction Decomposition and Analysis
-//===----------------------------------------------------------------------===//
+
+ struct VariableGEPIndex {
+ const Value *V;
+ ExtensionKind Extension;
+ int64_t Scale;
+ };
+}
/// GetLinearExpression - Analyze the specified value as a linear expression:
/// "A*V + B", where A and B are constant integers. Return the scale and offset
-/// values as APInts and return V as a Value*. The incoming Value is known to
-/// have IntegerType. Note that this looks through extends, so the high bits
-/// may not be represented in the result.
+/// values as APInts and return V as a Value*, and return whether we looked
+/// through any sign or zero extends. The incoming Value is known to have
+/// IntegerType and it may already be sign or zero extended.
+///
+/// Note that this looks through extends, so the high bits may not be
+/// represented in the result.
static Value *GetLinearExpression(Value *V, APInt &Scale, APInt &Offset,
- const TargetData *TD, unsigned Depth) {
+ ExtensionKind &Extension,
+ const TargetData &TD, unsigned Depth) {
assert(V->getType()->isIntegerTy() && "Not an integer value");
// Limit our recursion depth.
case Instruction::Or:
// X|C == X+C if all the bits in C are unset in X. Otherwise we can't
// analyze it.
- if (!MaskedValueIsZero(BOp->getOperand(0), RHSC->getValue(), TD))
+ if (!MaskedValueIsZero(BOp->getOperand(0), RHSC->getValue(), &TD))
break;
// FALL THROUGH.
case Instruction::Add:
- V = GetLinearExpression(BOp->getOperand(0), Scale, Offset, TD, Depth+1);
+ V = GetLinearExpression(BOp->getOperand(0), Scale, Offset, Extension,
+ TD, Depth+1);
Offset += RHSC->getValue();
return V;
case Instruction::Mul:
- V = GetLinearExpression(BOp->getOperand(0), Scale, Offset, TD, Depth+1);
+ V = GetLinearExpression(BOp->getOperand(0), Scale, Offset, Extension,
+ TD, Depth+1);
Offset *= RHSC->getValue();
Scale *= RHSC->getValue();
return V;
case Instruction::Shl:
- V = GetLinearExpression(BOp->getOperand(0), Scale, Offset, TD, Depth+1);
+ V = GetLinearExpression(BOp->getOperand(0), Scale, Offset, Extension,
+ TD, Depth+1);
Offset <<= RHSC->getValue().getLimitedValue();
Scale <<= RHSC->getValue().getLimitedValue();
return V;
}
// Since GEP indices are sign extended anyway, we don't care about the high
- // bits of a sign extended value - just scales and offsets.
- if (isa<SExtInst>(V)) {
+ // bits of a sign or zero extended value - just scales and offsets. The
+ // extensions have to be consistent though.
+ if ((isa<SExtInst>(V) && Extension != EK_ZeroExt) ||
+ (isa<ZExtInst>(V) && Extension != EK_SignExt)) {
Value *CastOp = cast<CastInst>(V)->getOperand(0);
unsigned OldWidth = Scale.getBitWidth();
unsigned SmallWidth = CastOp->getType()->getPrimitiveSizeInBits();
- Scale.trunc(SmallWidth);
- Offset.trunc(SmallWidth);
- Value *Result = GetLinearExpression(CastOp, Scale, Offset, TD, Depth+1);
- Scale.zext(OldWidth);
- Offset.zext(OldWidth);
+ Scale = Scale.trunc(SmallWidth);
+ Offset = Offset.trunc(SmallWidth);
+ Extension = isa<SExtInst>(V) ? EK_SignExt : EK_ZeroExt;
+
+ Value *Result = GetLinearExpression(CastOp, Scale, Offset, Extension,
+ TD, Depth+1);
+ Scale = Scale.zext(OldWidth);
+ Offset = Offset.zext(OldWidth);
+
return Result;
}
/// the gep cannot necessarily be reconstructed from its decomposed form.
///
/// When TargetData is around, this function is capable of analyzing everything
-/// that Value::getUnderlyingObject() can look through. When not, it just looks
+/// that GetUnderlyingObject can look through. When not, it just looks
/// through pointer casts.
///
static const Value *
DecomposeGEPExpression(const Value *V, int64_t &BaseOffs,
- SmallVectorImpl<std::pair<const Value*, int64_t> > &VarIndices,
+ SmallVectorImpl<VariableGEPIndex> &VarIndices,
const TargetData *TD) {
// Limit recursion depth to limit compile time in crazy cases.
unsigned MaxLookup = 6;
BaseOffs = 0;
do {
- // Look through global aliases and bitcasts.
- V = V->stripPointerCasts();
+ // See if this is a bitcast or GEP.
+ const Operator *Op = dyn_cast<Operator>(V);
+ if (Op == 0) {
+ // The only non-operator case we can handle are GlobalAliases.
+ if (const GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
+ if (!GA->mayBeOverridden()) {
+ V = GA->getAliasee();
+ continue;
+ }
+ }
+ return V;
+ }
+
+ if (Op->getOpcode() == Instruction::BitCast) {
+ V = Op->getOperand(0);
+ continue;
+ }
+
+ if (const Instruction *I = dyn_cast<Instruction>(V))
+ // TODO: Get a DominatorTree and use it here.
+ if (const Value *Simplified =
+ SimplifyInstruction(const_cast<Instruction *>(I), TD)) {
+ V = Simplified;
+ continue;
+ }
- const GEPOperator *GEPOp = dyn_cast<GEPOperator>(V);
+ const GEPOperator *GEPOp = dyn_cast<GEPOperator>(Op);
if (GEPOp == 0)
return V;
// If we are lacking TargetData information, we can't compute the offets of
// elements computed by GEPs. However, we can handle bitcast equivalent
// GEPs.
- if (!TD) {
+ if (TD == 0) {
if (!GEPOp->hasAllZeroIndices())
return V;
V = GEPOp->getOperand(0);
}
uint64_t Scale = TD->getTypeAllocSize(*GTI);
+ ExtensionKind Extension = EK_NotExtended;
- // Use GetLinearExpression to decompose the index into a C1*V+C2 form.
+ // If the integer type is smaller than the pointer size, it is implicitly
+ // sign extended to pointer size.
unsigned Width = cast<IntegerType>(Index->getType())->getBitWidth();
+ if (TD->getPointerSizeInBits() > Width)
+ Extension = EK_SignExt;
+
+ // Use GetLinearExpression to decompose the index into a C1*V+C2 form.
APInt IndexScale(Width, 0), IndexOffset(Width, 0);
- Index = GetLinearExpression(Index, IndexScale, IndexOffset, TD, 0);
+ Index = GetLinearExpression(Index, IndexScale, IndexOffset, Extension,
+ *TD, 0);
// The GEP index scale ("Scale") scales C1*V+C2, yielding (C1*V+C2)*Scale.
// This gives us an aggregate computation of (C1*Scale)*V + C2*Scale.
- BaseOffs += IndexOffset.getZExtValue()*Scale;
- Scale *= IndexScale.getZExtValue();
+ BaseOffs += IndexOffset.getSExtValue()*Scale;
+ Scale *= IndexScale.getSExtValue();
// If we already had an occurrance of this index variable, merge this
// A[x][x] -> x*16 + x*4 -> x*20
// This also ensures that 'x' only appears in the index list once.
for (unsigned i = 0, e = VarIndices.size(); i != e; ++i) {
- if (VarIndices[i].first == Index) {
- Scale += VarIndices[i].second;
+ if (VarIndices[i].V == Index &&
+ VarIndices[i].Extension == Extension) {
+ Scale += VarIndices[i].Scale;
VarIndices.erase(VarIndices.begin()+i);
break;
}
// pointer size.
if (unsigned ShiftBits = 64-TD->getPointerSizeInBits()) {
Scale <<= ShiftBits;
- Scale >>= ShiftBits;
+ Scale = (int64_t)Scale >> ShiftBits;
}
- if (Scale)
- VarIndices.push_back(std::make_pair(Index, Scale));
+ if (Scale) {
+ VariableGEPIndex Entry = {Index, Extension, Scale};
+ VarIndices.push_back(Entry);
+ }
}
// Analyze the base pointer next.
/// decomposed GetElementPtr instructions GEP1 and GEP2 which have common base
/// pointers. Subtract the GEP2 indices from GEP1 to find the symbolic
/// difference between the two pointers.
-static void GetIndexDifference(
- SmallVectorImpl<std::pair<const Value*, int64_t> > &Dest,
- const SmallVectorImpl<std::pair<const Value*, int64_t> > &Src) {
+static void GetIndexDifference(SmallVectorImpl<VariableGEPIndex> &Dest,
+ const SmallVectorImpl<VariableGEPIndex> &Src) {
if (Src.empty()) return;
for (unsigned i = 0, e = Src.size(); i != e; ++i) {
- const Value *V = Src[i].first;
- int64_t Scale = Src[i].second;
+ const Value *V = Src[i].V;
+ ExtensionKind Extension = Src[i].Extension;
+ int64_t Scale = Src[i].Scale;
// Find V in Dest. This is N^2, but pointer indices almost never have more
// than a few variable indexes.
for (unsigned j = 0, e = Dest.size(); j != e; ++j) {
- if (Dest[j].first != V) continue;
+ if (Dest[j].V != V || Dest[j].Extension != Extension) continue;
// If we found it, subtract off Scale V's from the entry in Dest. If it
// goes to zero, remove the entry.
- if (Dest[j].second != Scale)
- Dest[j].second -= Scale;
+ if (Dest[j].Scale != Scale)
+ Dest[j].Scale -= Scale;
else
Dest.erase(Dest.begin()+j);
Scale = 0;
}
// If we didn't consume this entry, add it to the end of the Dest list.
- if (Scale)
- Dest.push_back(std::make_pair(V, -Scale));
+ if (Scale) {
+ VariableGEPIndex Entry = { V, Extension, -Scale };
+ Dest.push_back(Entry);
+ }
}
}
#endif
namespace {
- /// BasicAliasAnalysis - This is the default alias analysis implementation.
- /// Because it doesn't chain to a previous alias analysis (like -no-aa), it
- /// derives from the NoAA class.
- struct BasicAliasAnalysis : public NoAA {
+ /// BasicAliasAnalysis - This is the primary alias analysis implementation.
+ struct BasicAliasAnalysis : public ImmutablePass, public AliasAnalysis {
static char ID; // Class identification, replacement for typeinfo
- BasicAliasAnalysis() : NoAA(ID) {}
+ BasicAliasAnalysis() : ImmutablePass(ID) {
+ initializeBasicAliasAnalysisPass(*PassRegistry::getPassRegistry());
+ }
+
+ virtual void initializePass() {
+ InitializeAliasAnalysis(this);
+ }
- virtual AliasResult alias(const Value *V1, unsigned V1Size,
- const Value *V2, unsigned V2Size) {
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<AliasAnalysis>();
+ }
+
+ virtual AliasResult alias(const Location &LocA,
+ const Location &LocB) {
assert(Visited.empty() && "Visited must be cleared after use!");
- assert(notDifferentParent(V1, V2) &&
+ assert(notDifferentParent(LocA.Ptr, LocB.Ptr) &&
"BasicAliasAnalysis doesn't support interprocedural queries.");
- AliasResult Alias = aliasCheck(V1, V1Size, V2, V2Size);
+ AliasResult Alias = aliasCheck(LocA.Ptr, LocA.Size, LocA.TBAATag,
+ LocB.Ptr, LocB.Size, LocB.TBAATag);
Visited.clear();
return Alias;
}
virtual ModRefResult getModRefInfo(ImmutableCallSite CS,
- const Value *P, unsigned Size);
+ const Location &Loc);
virtual ModRefResult getModRefInfo(ImmutableCallSite CS1,
ImmutableCallSite CS2) {
/// pointsToConstantMemory - Chase pointers until we find a (constant
/// global) or not.
- virtual bool pointsToConstantMemory(const Value *P);
+ virtual bool pointsToConstantMemory(const Location &Loc, bool OrLocal);
/// getModRefBehavior - Return the behavior when calling the given
/// call site.
// aliasGEP - Provide a bunch of ad-hoc rules to disambiguate a GEP
// instruction against another.
- AliasResult aliasGEP(const GEPOperator *V1, unsigned V1Size,
- const Value *V2, unsigned V2Size,
+ AliasResult aliasGEP(const GEPOperator *V1, uint64_t V1Size,
+ const Value *V2, uint64_t V2Size,
+ const MDNode *V2TBAAInfo,
const Value *UnderlyingV1, const Value *UnderlyingV2);
// aliasPHI - Provide a bunch of ad-hoc rules to disambiguate a PHI
// instruction against another.
- AliasResult aliasPHI(const PHINode *PN, unsigned PNSize,
- const Value *V2, unsigned V2Size);
+ AliasResult aliasPHI(const PHINode *PN, uint64_t PNSize,
+ const MDNode *PNTBAAInfo,
+ const Value *V2, uint64_t V2Size,
+ const MDNode *V2TBAAInfo);
/// aliasSelect - Disambiguate a Select instruction against another value.
- AliasResult aliasSelect(const SelectInst *SI, unsigned SISize,
- const Value *V2, unsigned V2Size);
-
- AliasResult aliasCheck(const Value *V1, unsigned V1Size,
- const Value *V2, unsigned V2Size);
+ AliasResult aliasSelect(const SelectInst *SI, uint64_t SISize,
+ const MDNode *SITBAAInfo,
+ const Value *V2, uint64_t V2Size,
+ const MDNode *V2TBAAInfo);
+
+ AliasResult aliasCheck(const Value *V1, uint64_t V1Size,
+ const MDNode *V1TBAATag,
+ const Value *V2, uint64_t V2Size,
+ const MDNode *V2TBAATag);
};
} // End of anonymous namespace
// Register this pass...
char BasicAliasAnalysis::ID = 0;
INITIALIZE_AG_PASS(BasicAliasAnalysis, AliasAnalysis, "basicaa",
- "Basic Alias Analysis (default AA impl)",
- false, true, true);
+ "Basic Alias Analysis (stateless AA impl)",
+ false, true, false)
ImmutablePass *llvm::createBasicAliasAnalysisPass() {
return new BasicAliasAnalysis();
}
+/// pointsToConstantMemory - Returns whether the given pointer value
+/// points to memory that is local to the function, with global constants being
+/// considered local to all functions.
+bool
+BasicAliasAnalysis::pointsToConstantMemory(const Location &Loc, bool OrLocal) {
+ assert(Visited.empty() && "Visited must be cleared after use!");
+
+ unsigned MaxLookup = 8;
+ SmallVector<const Value *, 16> Worklist;
+ Worklist.push_back(Loc.Ptr);
+ do {
+ const Value *V = GetUnderlyingObject(Worklist.pop_back_val());
+ if (!Visited.insert(V)) {
+ Visited.clear();
+ return AliasAnalysis::pointsToConstantMemory(Loc, OrLocal);
+ }
+
+ // An alloca instruction defines local memory.
+ if (OrLocal && isa<AllocaInst>(V))
+ continue;
+
+ // A global constant counts as local memory for our purposes.
+ if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
+ // Note: this doesn't require GV to be "ODR" because it isn't legal for a
+ // global to be marked constant in some modules and non-constant in
+ // others. GV may even be a declaration, not a definition.
+ if (!GV->isConstant()) {
+ Visited.clear();
+ return AliasAnalysis::pointsToConstantMemory(Loc, OrLocal);
+ }
+ continue;
+ }
+
+ // If both select values point to local memory, then so does the select.
+ if (const SelectInst *SI = dyn_cast<SelectInst>(V)) {
+ Worklist.push_back(SI->getTrueValue());
+ Worklist.push_back(SI->getFalseValue());
+ continue;
+ }
-/// pointsToConstantMemory - Chase pointers until we find a (constant
-/// global) or not.
-bool BasicAliasAnalysis::pointsToConstantMemory(const Value *P) {
- if (const GlobalVariable *GV =
- dyn_cast<GlobalVariable>(P->getUnderlyingObject()))
- // Note: this doesn't require GV to be "ODR" because it isn't legal for a
- // global to be marked constant in some modules and non-constant in others.
- // GV may even be a declaration, not a definition.
- return GV->isConstant();
+ // If all values incoming to a phi node point to local memory, then so does
+ // the phi.
+ if (const PHINode *PN = dyn_cast<PHINode>(V)) {
+ // Don't bother inspecting phi nodes with many operands.
+ if (PN->getNumIncomingValues() > MaxLookup) {
+ Visited.clear();
+ return AliasAnalysis::pointsToConstantMemory(Loc, OrLocal);
+ }
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+ Worklist.push_back(PN->getIncomingValue(i));
+ continue;
+ }
+
+ // Otherwise be conservative.
+ Visited.clear();
+ return AliasAnalysis::pointsToConstantMemory(Loc, OrLocal);
+
+ } while (!Worklist.empty() && --MaxLookup);
- return NoAA::pointsToConstantMemory(P);
+ Visited.clear();
+ return Worklist.empty();
}
/// getModRefBehavior - Return the behavior when calling the given call site.
Min = OnlyReadsMemory;
// The AliasAnalysis base class has some smarts, lets use them.
- return std::min(AliasAnalysis::getModRefBehavior(CS), Min);
+ return ModRefBehavior(AliasAnalysis::getModRefBehavior(CS) & Min);
}
/// getModRefBehavior - Return the behavior when calling the given function.
/// For use when the call site is not known.
AliasAnalysis::ModRefBehavior
BasicAliasAnalysis::getModRefBehavior(const Function *F) {
+ // If the function declares it doesn't access memory, we can't do better.
if (F->doesNotAccessMemory())
- // Can't do better than this.
return DoesNotAccessMemory;
+
+ // For intrinsics, we can check the table.
+ if (unsigned iid = F->getIntrinsicID()) {
+#define GET_INTRINSIC_MODREF_BEHAVIOR
+#include "llvm/Intrinsics.gen"
+#undef GET_INTRINSIC_MODREF_BEHAVIOR
+ }
+
+ ModRefBehavior Min = UnknownModRefBehavior;
+
+ // If the function declares it only reads memory, go with that.
if (F->onlyReadsMemory())
- return OnlyReadsMemory;
- if (unsigned id = F->getIntrinsicID())
- return getIntrinsicModRefBehavior(id);
+ Min = OnlyReadsMemory;
- return NoAA::getModRefBehavior(F);
+ // Otherwise be conservative.
+ return ModRefBehavior(AliasAnalysis::getModRefBehavior(F) & Min);
}
/// getModRefInfo - Check to see if the specified callsite can clobber the
/// simple "address taken" analysis on local objects.
AliasAnalysis::ModRefResult
BasicAliasAnalysis::getModRefInfo(ImmutableCallSite CS,
- const Value *P, unsigned Size) {
- assert(notDifferentParent(CS.getInstruction(), P) &&
+ const Location &Loc) {
+ assert(notDifferentParent(CS.getInstruction(), Loc.Ptr) &&
"AliasAnalysis query involving multiple functions!");
- const Value *Object = P->getUnderlyingObject();
+ const Value *Object = GetUnderlyingObject(Loc.Ptr);
- // If this is a tail call and P points to a stack location, we know that
+ // If this is a tail call and Loc.Ptr points to a stack location, we know that
// the tail call cannot access or modify the local stack.
// We cannot exclude byval arguments here; these belong to the caller of
// the current function not to the current function, and a tail callee
!CS.paramHasAttr(ArgNo+1, Attribute::NoCapture))
continue;
- // If this is a no-capture pointer argument, see if we can tell that it
+ // If this is a no-capture pointer argument, see if we can tell that it
// is impossible to alias the pointer we're checking. If not, we have to
// assume that the call could touch the pointer, even though it doesn't
// escape.
- if (!isNoAlias(cast<Value>(CI), UnknownSize, P, UnknownSize)) {
+ if (!isNoAlias(Location(cast<Value>(CI)), Loc)) {
PassedAsArg = true;
break;
}
return NoModRef;
}
+ ModRefResult Min = ModRef;
+
// Finally, handle specific knowledge of intrinsics.
const IntrinsicInst *II = dyn_cast<IntrinsicInst>(CS.getInstruction());
if (II != 0)
default: break;
case Intrinsic::memcpy:
case Intrinsic::memmove: {
- unsigned Len = UnknownSize;
+ uint64_t Len = UnknownSize;
if (ConstantInt *LenCI = dyn_cast<ConstantInt>(II->getArgOperand(2)))
Len = LenCI->getZExtValue();
Value *Dest = II->getArgOperand(0);
Value *Src = II->getArgOperand(1);
- if (isNoAlias(Dest, Len, P, Size)) {
- if (isNoAlias(Src, Len, P, Size))
+ // If it can't overlap the source dest, then it doesn't modref the loc.
+ if (isNoAlias(Location(Dest, Len), Loc)) {
+ if (isNoAlias(Location(Src, Len), Loc))
return NoModRef;
- return Ref;
+ // If it can't overlap the dest, then worst case it reads the loc.
+ Min = Ref;
+ } else if (isNoAlias(Location(Src, Len), Loc)) {
+ // If it can't overlap the source, then worst case it mutates the loc.
+ Min = Mod;
}
break;
}
// Since memset is 'accesses arguments' only, the AliasAnalysis base class
// will handle it for the variable length case.
if (ConstantInt *LenCI = dyn_cast<ConstantInt>(II->getArgOperand(2))) {
- unsigned Len = LenCI->getZExtValue();
+ uint64_t Len = LenCI->getZExtValue();
Value *Dest = II->getArgOperand(0);
- if (isNoAlias(Dest, Len, P, Size))
+ if (isNoAlias(Location(Dest, Len), Loc))
return NoModRef;
}
+ // We know that memset doesn't load anything.
+ Min = Mod;
break;
case Intrinsic::atomic_cmp_swap:
case Intrinsic::atomic_swap:
case Intrinsic::atomic_load_umin:
if (TD) {
Value *Op1 = II->getArgOperand(0);
- unsigned Op1Size = TD->getTypeStoreSize(Op1->getType());
- if (isNoAlias(Op1, Op1Size, P, Size))
+ uint64_t Op1Size = TD->getTypeStoreSize(Op1->getType());
+ MDNode *Tag = II->getMetadata(LLVMContext::MD_tbaa);
+ if (isNoAlias(Location(Op1, Op1Size, Tag), Loc))
return NoModRef;
}
break;
case Intrinsic::lifetime_start:
case Intrinsic::lifetime_end:
case Intrinsic::invariant_start: {
- unsigned PtrSize =
+ uint64_t PtrSize =
cast<ConstantInt>(II->getArgOperand(0))->getZExtValue();
- if (isNoAlias(II->getArgOperand(1), PtrSize, P, Size))
+ if (isNoAlias(Location(II->getArgOperand(1),
+ PtrSize,
+ II->getMetadata(LLVMContext::MD_tbaa)),
+ Loc))
return NoModRef;
break;
}
case Intrinsic::invariant_end: {
- unsigned PtrSize =
+ uint64_t PtrSize =
cast<ConstantInt>(II->getArgOperand(1))->getZExtValue();
- if (isNoAlias(II->getArgOperand(2), PtrSize, P, Size))
+ if (isNoAlias(Location(II->getArgOperand(2),
+ PtrSize,
+ II->getMetadata(LLVMContext::MD_tbaa)),
+ Loc))
return NoModRef;
break;
}
}
// The AliasAnalysis base class has some smarts, lets use them.
- return AliasAnalysis::getModRefInfo(CS, P, Size);
+ return ModRefResult(AliasAnalysis::getModRefInfo(CS, Loc) & Min);
}
-
/// aliasGEP - Provide a bunch of ad-hoc rules to disambiguate a GEP instruction
/// against another pointer. We know that V1 is a GEP, but we don't know
-/// anything about V2. UnderlyingV1 is GEP1->getUnderlyingObject(),
+/// anything about V2. UnderlyingV1 is GetUnderlyingObject(GEP1),
/// UnderlyingV2 is the same for V2.
///
AliasAnalysis::AliasResult
-BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, unsigned V1Size,
- const Value *V2, unsigned V2Size,
+BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size,
+ const Value *V2, uint64_t V2Size,
+ const MDNode *V2TBAAInfo,
const Value *UnderlyingV1,
const Value *UnderlyingV2) {
// If this GEP has been visited before, we're on a use-def cycle.
return MayAlias;
int64_t GEP1BaseOffset;
- SmallVector<std::pair<const Value*, int64_t>, 4> GEP1VariableIndices;
+ SmallVector<VariableGEPIndex, 4> GEP1VariableIndices;
// If we have two gep instructions with must-alias'ing base pointers, figure
// out if the indexes to the GEP tell us anything about the derived pointer.
if (const GEPOperator *GEP2 = dyn_cast<GEPOperator>(V2)) {
// Do the base pointers alias?
- AliasResult BaseAlias = aliasCheck(UnderlyingV1, UnknownSize,
- UnderlyingV2, UnknownSize);
+ AliasResult BaseAlias = aliasCheck(UnderlyingV1, UnknownSize, 0,
+ UnderlyingV2, UnknownSize, 0);
// If we get a No or May, then return it immediately, no amount of analysis
// will improve this situation.
DecomposeGEPExpression(GEP1, GEP1BaseOffset, GEP1VariableIndices, TD);
int64_t GEP2BaseOffset;
- SmallVector<std::pair<const Value*, int64_t>, 4> GEP2VariableIndices;
+ SmallVector<VariableGEPIndex, 4> GEP2VariableIndices;
const Value *GEP2BasePtr =
DecomposeGEPExpression(GEP2, GEP2BaseOffset, GEP2VariableIndices, TD);
// to handle without it.
if (GEP1BasePtr != UnderlyingV1 || GEP2BasePtr != UnderlyingV2) {
assert(TD == 0 &&
- "DecomposeGEPExpression and getUnderlyingObject disagree!");
+ "DecomposeGEPExpression and GetUnderlyingObject disagree!");
return MayAlias;
}
if (V1Size == UnknownSize && V2Size == UnknownSize)
return MayAlias;
- AliasResult R = aliasCheck(UnderlyingV1, UnknownSize, V2, V2Size);
+ AliasResult R = aliasCheck(UnderlyingV1, UnknownSize, 0,
+ V2, V2Size, V2TBAAInfo);
if (R != MustAlias)
// If V2 may alias GEP base pointer, conservatively returns MayAlias.
// If V2 is known not to alias GEP base pointer, then the two values
// to handle without it.
if (GEP1BasePtr != UnderlyingV1) {
assert(TD == 0 &&
- "DecomposeGEPExpression and getUnderlyingObject disagree!");
+ "DecomposeGEPExpression and GetUnderlyingObject disagree!");
return MayAlias;
}
}
if (GEP1BaseOffset == 0 && GEP1VariableIndices.empty())
return MustAlias;
+ // If there is a difference betwen the pointers, but the difference is
+ // less than the size of the associated memory object, then we know
+ // that the objects are partially overlapping.
+ if (GEP1BaseOffset != 0 && GEP1VariableIndices.empty()) {
+ if (GEP1BaseOffset >= 0 ?
+ (V2Size != UnknownSize && (uint64_t)GEP1BaseOffset < V2Size) :
+ (V1Size != UnknownSize && -(uint64_t)GEP1BaseOffset < V1Size &&
+ GEP1BaseOffset != INT64_MIN))
+ return PartialAlias;
+ }
+
// If we have a known constant offset, see if this offset is larger than the
// access size being queried. If so, and if no variable indices can remove
// pieces of this constant, then we know we have a no-alias. For example,
// provides an offset of 4 bytes (assuming a <= 4 byte access).
for (unsigned i = 0, e = GEP1VariableIndices.size();
i != e && GEP1BaseOffset;++i)
- if (int64_t RemovedOffset = GEP1BaseOffset/GEP1VariableIndices[i].second)
- GEP1BaseOffset -= RemovedOffset*GEP1VariableIndices[i].second;
+ if (int64_t RemovedOffset = GEP1BaseOffset/GEP1VariableIndices[i].Scale)
+ GEP1BaseOffset -= RemovedOffset*GEP1VariableIndices[i].Scale;
// If our known offset is bigger than the access size, we know we don't have
// an alias.
if (GEP1BaseOffset) {
- if (GEP1BaseOffset >= (int64_t)V2Size ||
- GEP1BaseOffset <= -(int64_t)V1Size)
+ if (GEP1BaseOffset >= 0 ?
+ (V2Size != UnknownSize && (uint64_t)GEP1BaseOffset >= V2Size) :
+ (V1Size != UnknownSize && -(uint64_t)GEP1BaseOffset >= V1Size &&
+ GEP1BaseOffset != INT64_MIN))
return NoAlias;
}
/// aliasSelect - Provide a bunch of ad-hoc rules to disambiguate a Select
/// instruction against another.
AliasAnalysis::AliasResult
-BasicAliasAnalysis::aliasSelect(const SelectInst *SI, unsigned SISize,
- const Value *V2, unsigned V2Size) {
+BasicAliasAnalysis::aliasSelect(const SelectInst *SI, uint64_t SISize,
+ const MDNode *SITBAAInfo,
+ const Value *V2, uint64_t V2Size,
+ const MDNode *V2TBAAInfo) {
// If this select has been visited before, we're on a use-def cycle.
// Such cycles are only valid when PHI nodes are involved or in unreachable
// code. The visitPHI function catches cycles containing PHIs, but there
if (const SelectInst *SI2 = dyn_cast<SelectInst>(V2))
if (SI->getCondition() == SI2->getCondition()) {
AliasResult Alias =
- aliasCheck(SI->getTrueValue(), SISize,
- SI2->getTrueValue(), V2Size);
+ aliasCheck(SI->getTrueValue(), SISize, SITBAAInfo,
+ SI2->getTrueValue(), V2Size, V2TBAAInfo);
if (Alias == MayAlias)
return MayAlias;
AliasResult ThisAlias =
- aliasCheck(SI->getFalseValue(), SISize,
- SI2->getFalseValue(), V2Size);
+ aliasCheck(SI->getFalseValue(), SISize, SITBAAInfo,
+ SI2->getFalseValue(), V2Size, V2TBAAInfo);
if (ThisAlias != Alias)
return MayAlias;
return Alias;
// If both arms of the Select node NoAlias or MustAlias V2, then returns
// NoAlias / MustAlias. Otherwise, returns MayAlias.
AliasResult Alias =
- aliasCheck(V2, V2Size, SI->getTrueValue(), SISize);
+ aliasCheck(V2, V2Size, V2TBAAInfo, SI->getTrueValue(), SISize, SITBAAInfo);
if (Alias == MayAlias)
return MayAlias;
Visited.erase(V2);
AliasResult ThisAlias =
- aliasCheck(V2, V2Size, SI->getFalseValue(), SISize);
+ aliasCheck(V2, V2Size, V2TBAAInfo, SI->getFalseValue(), SISize, SITBAAInfo);
if (ThisAlias != Alias)
return MayAlias;
return Alias;
// aliasPHI - Provide a bunch of ad-hoc rules to disambiguate a PHI instruction
// against another.
AliasAnalysis::AliasResult
-BasicAliasAnalysis::aliasPHI(const PHINode *PN, unsigned PNSize,
- const Value *V2, unsigned V2Size) {
+BasicAliasAnalysis::aliasPHI(const PHINode *PN, uint64_t PNSize,
+ const MDNode *PNTBAAInfo,
+ const Value *V2, uint64_t V2Size,
+ const MDNode *V2TBAAInfo) {
// The PHI node has already been visited, avoid recursion any further.
if (!Visited.insert(PN))
return MayAlias;
if (const PHINode *PN2 = dyn_cast<PHINode>(V2))
if (PN2->getParent() == PN->getParent()) {
AliasResult Alias =
- aliasCheck(PN->getIncomingValue(0), PNSize,
+ aliasCheck(PN->getIncomingValue(0), PNSize, PNTBAAInfo,
PN2->getIncomingValueForBlock(PN->getIncomingBlock(0)),
- V2Size);
+ V2Size, V2TBAAInfo);
if (Alias == MayAlias)
return MayAlias;
for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) {
AliasResult ThisAlias =
- aliasCheck(PN->getIncomingValue(i), PNSize,
+ aliasCheck(PN->getIncomingValue(i), PNSize, PNTBAAInfo,
PN2->getIncomingValueForBlock(PN->getIncomingBlock(i)),
- V2Size);
+ V2Size, V2TBAAInfo);
if (ThisAlias != Alias)
return MayAlias;
}
V1Srcs.push_back(PV1);
}
- AliasResult Alias = aliasCheck(V2, V2Size, V1Srcs[0], PNSize);
+ AliasResult Alias = aliasCheck(V2, V2Size, V2TBAAInfo,
+ V1Srcs[0], PNSize, PNTBAAInfo);
// Early exit if the check of the first PHI source against V2 is MayAlias.
// Other results are not possible.
if (Alias == MayAlias)
// don't need to assume that V2 is being visited recursively.
Visited.erase(V2);
- AliasResult ThisAlias = aliasCheck(V2, V2Size, V, PNSize);
+ AliasResult ThisAlias = aliasCheck(V2, V2Size, V2TBAAInfo,
+ V, PNSize, PNTBAAInfo);
if (ThisAlias != Alias || ThisAlias == MayAlias)
return MayAlias;
}
// such as array references.
//
AliasAnalysis::AliasResult
-BasicAliasAnalysis::aliasCheck(const Value *V1, unsigned V1Size,
- const Value *V2, unsigned V2Size) {
+BasicAliasAnalysis::aliasCheck(const Value *V1, uint64_t V1Size,
+ const MDNode *V1TBAAInfo,
+ const Value *V2, uint64_t V2Size,
+ const MDNode *V2TBAAInfo) {
// If either of the memory references is empty, it doesn't matter what the
// pointer values are.
if (V1Size == 0 || V2Size == 0)
return NoAlias; // Scalars cannot alias each other
// Figure out what objects these things are pointing to if we can.
- const Value *O1 = V1->getUnderlyingObject();
- const Value *O2 = V2->getUnderlyingObject();
+ const Value *O1 = GetUnderlyingObject(V1);
+ const Value *O2 = GetUnderlyingObject(V2);
// Null values in the default address space don't point to any object, so they
// don't alias any other pointer.
std::swap(V1Size, V2Size);
std::swap(O1, O2);
}
- if (const GEPOperator *GV1 = dyn_cast<GEPOperator>(V1))
- return aliasGEP(GV1, V1Size, V2, V2Size, O1, O2);
+ if (const GEPOperator *GV1 = dyn_cast<GEPOperator>(V1)) {
+ AliasResult Result = aliasGEP(GV1, V1Size, V2, V2Size, V2TBAAInfo, O1, O2);
+ if (Result != MayAlias) return Result;
+ }
if (isa<PHINode>(V2) && !isa<PHINode>(V1)) {
std::swap(V1, V2);
std::swap(V1Size, V2Size);
}
- if (const PHINode *PN = dyn_cast<PHINode>(V1))
- return aliasPHI(PN, V1Size, V2, V2Size);
+ if (const PHINode *PN = dyn_cast<PHINode>(V1)) {
+ AliasResult Result = aliasPHI(PN, V1Size, V1TBAAInfo,
+ V2, V2Size, V2TBAAInfo);
+ if (Result != MayAlias) return Result;
+ }
if (isa<SelectInst>(V2) && !isa<SelectInst>(V1)) {
std::swap(V1, V2);
std::swap(V1Size, V2Size);
}
- if (const SelectInst *S1 = dyn_cast<SelectInst>(V1))
- return aliasSelect(S1, V1Size, V2, V2Size);
+ if (const SelectInst *S1 = dyn_cast<SelectInst>(V1)) {
+ AliasResult Result = aliasSelect(S1, V1Size, V1TBAAInfo,
+ V2, V2Size, V2TBAAInfo);
+ if (Result != MayAlias) return Result;
+ }
- return NoAA::alias(V1, V1Size, V2, V2Size);
+ return AliasAnalysis::alias(Location(V1, V1Size, V1TBAAInfo),
+ Location(V2, V2Size, V2TBAAInfo));
}
-
-// Make sure that anything that uses AliasAnalysis pulls in this file.
-DEFINING_FILE_FOR(BasicAliasAnalysis)
projects / oota-llvm.git / blobdiff