#include "llvm/IR/Instruction.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
-#include "llvm/Pass.h"
+#include "llvm/IR/PassManager.h"
#include "llvm/Support/ErrorHandling.h"
namespace llvm {
+class AssumptionCache;
+class DominatorTree;
+class LoopInfo;
+
+/// This is the AA result object for the basic, local, and stateless alias
+/// analysis. It implements the AA query interface in an entirely stateless
+/// manner. As one consequence, it is never invalidated. While it does retain
+/// some storage, that is used as an optimization and not to preserve
+/// information from query to query.
+class BasicAAResult : public AAResultBase<BasicAAResult> {
+ friend AAResultBase<BasicAAResult>;
+
+ const DataLayout &DL;
+ AssumptionCache &AC;
+ DominatorTree *DT;
+ LoopInfo *LI;
+
+public:
+ BasicAAResult(const DataLayout &DL, const TargetLibraryInfo &TLI,
+ AssumptionCache &AC, DominatorTree *DT = nullptr,
+ LoopInfo *LI = nullptr)
+ : AAResultBase(TLI), DL(DL), AC(AC), DT(DT), LI(LI) {}
+
+ BasicAAResult(const BasicAAResult &Arg)
+ : AAResultBase(Arg), DL(Arg.DL), AC(Arg.AC), DT(Arg.DT), LI(Arg.LI) {}
+ BasicAAResult(BasicAAResult &&Arg)
+ : AAResultBase(std::move(Arg)), DL(Arg.DL), AC(Arg.AC), DT(Arg.DT),
+ LI(Arg.LI) {}
+
+ /// Handle invalidation events from the new pass manager.
+ ///
+ /// By definition, this result is stateless and so remains valid.
+ bool invalidate(Function &, const PreservedAnalyses &) { return false; }
-/// BasicAliasAnalysis - This is the primary alias analysis implementation.
-struct BasicAliasAnalysis : public ImmutablePass, public AliasAnalysis {
- static char ID; // Class identification, replacement for typeinfo
-
-#ifndef NDEBUG
- static const Function *getParent(const Value *V) {
- if (const Instruction *inst = dyn_cast<Instruction>(V))
- return inst->getParent()->getParent();
-
- if (const Argument *arg = dyn_cast<Argument>(V))
- return arg->getParent();
+ AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB);
- return nullptr;
- }
+ ModRefInfo getModRefInfo(ImmutableCallSite CS, const MemoryLocation &Loc);
- static bool notDifferentParent(const Value *O1, const Value *O2) {
+ ModRefInfo getModRefInfo(ImmutableCallSite CS1, ImmutableCallSite CS2);
- const Function *F1 = getParent(O1);
- const Function *F2 = getParent(O2);
+ /// Chases pointers until we find a (constant global) or not.
+ bool pointsToConstantMemory(const MemoryLocation &Loc, bool OrLocal);
- return !F1 || !F2 || F1 == F2;
- }
-#endif
+ /// Get the location associated with a pointer argument of a callsite.
+ ModRefInfo getArgModRefInfo(ImmutableCallSite CS, unsigned ArgIdx);
- BasicAliasAnalysis() : ImmutablePass(ID) {
- initializeBasicAliasAnalysisPass(*PassRegistry::getPassRegistry());
- }
-
- bool doInitialization(Module &M) override;
-
- void getAnalysisUsage(AnalysisUsage &AU) const override {
- AU.addRequired<AliasAnalysis>();
- AU.addRequired<AssumptionCacheTracker>();
- AU.addRequired<TargetLibraryInfoWrapperPass>();
- }
-
- AliasResult alias(const MemoryLocation &LocA,
- const MemoryLocation &LocB) override {
- assert(AliasCache.empty() && "AliasCache must be cleared after use!");
- assert(notDifferentParent(LocA.Ptr, LocB.Ptr) &&
- "BasicAliasAnalysis doesn't support interprocedural queries.");
- AliasResult Alias = aliasCheck(LocA.Ptr, LocA.Size, LocA.AATags, LocB.Ptr,
- LocB.Size, LocB.AATags);
- // AliasCache rarely has more than 1 or 2 elements, always use
- // shrink_and_clear so it quickly returns to the inline capacity of the
- // SmallDenseMap if it ever grows larger.
- // FIXME: This should really be shrink_to_inline_capacity_and_clear().
- AliasCache.shrink_and_clear();
- VisitedPhiBBs.clear();
- return Alias;
- }
-
- ModRefInfo getModRefInfo(ImmutableCallSite CS,
- const MemoryLocation &Loc) override;
-
- ModRefInfo getModRefInfo(ImmutableCallSite CS1,
- ImmutableCallSite CS2) override;
-
- /// pointsToConstantMemory - Chase pointers until we find a (constant
- /// global) or not.
- bool pointsToConstantMemory(const MemoryLocation &Loc, bool OrLocal) override;
+ /// Returns the behavior when calling the given call site.
+ FunctionModRefBehavior getModRefBehavior(ImmutableCallSite CS);
- /// Get the location associated with a pointer argument of a callsite.
- ModRefInfo getArgModRefInfo(ImmutableCallSite CS, unsigned ArgIdx) override;
-
- /// getModRefBehavior - Return the behavior when calling the given
- /// call site.
- FunctionModRefBehavior getModRefBehavior(ImmutableCallSite CS) override;
-
- /// getModRefBehavior - Return the behavior when calling the given function.
- /// For use when the call site is not known.
- FunctionModRefBehavior getModRefBehavior(const Function *F) override;
-
- /// 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.
- void *getAdjustedAnalysisPointer(const void *ID) override {
- if (ID == &AliasAnalysis::ID)
- return (AliasAnalysis *)this;
- return this;
- }
+ /// Returns the behavior when calling the given function. For use when the
+ /// call site is not known.
+ FunctionModRefBehavior getModRefBehavior(const Function *F);
private:
- enum ExtensionKind { EK_NotExtended, EK_SignExt, EK_ZeroExt };
-
+ // A linear transformation of a Value; this class represents ZExt(SExt(V,
+ // SExtBits), ZExtBits) * Scale + Offset.
struct VariableGEPIndex {
+
+ // An opaque Value - we can't decompose this further.
const Value *V;
- ExtensionKind Extension;
+
+ // We need to track what extensions we've done as we consider the same Value
+ // with different extensions as different variables in a GEP's linear
+ // expression;
+ // e.g.: if V == -1, then sext(x) != zext(x).
+ unsigned ZExtBits;
+ unsigned SExtBits;
+
int64_t Scale;
bool operator==(const VariableGEPIndex &Other) const {
- return V == Other.V && Extension == Other.Extension &&
- Scale == Other.Scale;
+ return V == Other.V && ZExtBits == Other.ZExtBits &&
+ SExtBits == Other.SExtBits && Scale == Other.Scale;
}
bool operator!=(const VariableGEPIndex &Other) const {
}
};
- // AliasCache - Track alias queries to guard against recursion.
+ /// Track alias queries to guard against recursion.
typedef std::pair<MemoryLocation, MemoryLocation> LocPair;
typedef SmallDenseMap<LocPair, AliasResult, 8> AliasCacheTy;
AliasCacheTy AliasCache;
- /// \brief Track phi nodes we have visited. When interpret "Value" pointer
- /// equality as value equality we need to make sure that the "Value" is not
- /// part of a cycle. Otherwise, two uses could come from different
- /// "iterations" of a cycle and see different values for the same "Value"
- /// pointer.
+ /// Tracks phi nodes we have visited.
+ ///
+ /// When interpret "Value" pointer equality as value equality we need to make
+ /// sure that the "Value" is not part of a cycle. Otherwise, two uses could
+ /// come from different "iterations" of a cycle and see different values for
+ /// the same "Value" pointer.
+ ///
/// The following example shows the problem:
/// %p = phi(%alloca1, %addr2)
/// %l = load %ptr
/// store %l, ...
SmallPtrSet<const BasicBlock *, 8> VisitedPhiBBs;
- // Visited - Track instructions visited by pointsToConstantMemory.
+ /// Tracks instructions visited by pointsToConstantMemory.
SmallPtrSet<const Value *, 16> Visited;
- static Value *GetLinearExpression(Value *V, APInt &Scale, APInt &Offset,
- ExtensionKind &Extension,
- const DataLayout &DL, unsigned Depth,
- AssumptionCache *AC, DominatorTree *DT);
+ static const Value *
+ GetLinearExpression(const Value *V, APInt &Scale, APInt &Offset,
+ unsigned &ZExtBits, unsigned &SExtBits,
+ const DataLayout &DL, unsigned Depth, AssumptionCache *AC,
+ DominatorTree *DT, bool &NSW, bool &NUW);
static const Value *
DecomposeGEPExpression(const Value *V, int64_t &BaseOffs,
SmallVectorImpl<VariableGEPIndex> &VarIndices,
bool &MaxLookupReached, const DataLayout &DL,
AssumptionCache *AC, DominatorTree *DT);
-
- /// \brief Check whether two Values can be considered equivalent.
+ /// \brief A Heuristic for aliasGEP that searches for a constant offset
+ /// between the variables.
///
- /// In addition to pointer equivalence of \p V1 and \p V2 this checks
- /// whether they can not be part of a cycle in the value graph by looking at
- /// all visited phi nodes an making sure that the phis cannot reach the
- /// value. We have to do this because we are looking through phi nodes (That
- /// is we say noalias(V, phi(VA, VB)) if noalias(V, VA) and noalias(V, VB).
+ /// GetLinearExpression has some limitations, as generally zext(%x + 1)
+ /// != zext(%x) + zext(1) if the arithmetic overflows. GetLinearExpression
+ /// will therefore conservatively refuse to decompose these expressions.
+ /// However, we know that, for all %x, zext(%x) != zext(%x + 1), even if
+ /// the addition overflows.
+ bool
+ constantOffsetHeuristic(const SmallVectorImpl<VariableGEPIndex> &VarIndices,
+ uint64_t V1Size, uint64_t V2Size, int64_t BaseOffset,
+ AssumptionCache *AC, DominatorTree *DT);
+
bool isValueEqualInPotentialCycles(const Value *V1, const Value *V2);
- /// \brief Dest and Src are the variable indices from two 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.
void GetIndexDifference(SmallVectorImpl<VariableGEPIndex> &Dest,
const SmallVectorImpl<VariableGEPIndex> &Src);
- // aliasGEP - Provide a bunch of ad-hoc rules to disambiguate a GEP
- // instruction against another.
AliasResult aliasGEP(const GEPOperator *V1, uint64_t V1Size,
const AAMDNodes &V1AAInfo, const Value *V2,
uint64_t V2Size, const AAMDNodes &V2AAInfo,
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, uint64_t PNSize,
const AAMDNodes &PNAAInfo, const Value *V2,
uint64_t V2Size, const AAMDNodes &V2AAInfo);
- /// aliasSelect - Disambiguate a Select instruction against another value.
AliasResult aliasSelect(const SelectInst *SI, uint64_t SISize,
const AAMDNodes &SIAAInfo, const Value *V2,
uint64_t V2Size, const AAMDNodes &V2AAInfo);
const Value *V2, uint64_t V2Size, AAMDNodes V2AATag);
};
-//===--------------------------------------------------------------------===//
-//
-// createBasicAliasAnalysisPass - This pass implements the stateless alias
-// analysis.
-//
-ImmutablePass *createBasicAliasAnalysisPass();
+/// Analysis pass providing a never-invalidated alias analysis result.
+class BasicAA {
+public:
+ typedef BasicAAResult Result;
+
+ /// \brief Opaque, unique identifier for this analysis pass.
+ static void *ID() { return (void *)&PassID; }
+
+ BasicAAResult run(Function &F, AnalysisManager<Function> *AM);
+
+ /// \brief Provide access to a name for this pass for debugging purposes.
+ static StringRef name() { return "BasicAliasAnalysis"; }
+
+private:
+ static char PassID;
+};
+
+/// Legacy wrapper pass to provide the BasicAAResult object.
+class BasicAAWrapperPass : public FunctionPass {
+ std::unique_ptr<BasicAAResult> Result;
+
+ virtual void anchor();
+
+public:
+ static char ID;
+
+ BasicAAWrapperPass();
+
+ BasicAAResult &getResult() { return *Result; }
+ const BasicAAResult &getResult() const { return *Result; }
+
+ bool runOnFunction(Function &F) override;
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+};
+
+FunctionPass *createBasicAAWrapperPass();
+/// A helper for the legacy pass manager to create a \c BasicAAResult object
+/// populated to the best of our ability for a particular function when inside
+/// of a \c ModulePass or a \c CallGraphSCCPass.
+BasicAAResult createLegacyPMBasicAAResult(Pass &P, Function &F);
}
#endif
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