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//===- GlobalsModRef.h - Simple Mod/Ref AA for Globals ----------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
/// \file
/// This is the interface for a simple mod/ref and alias analysis over globals.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_GLOBALSMODREF_H
#define LLVM_ANALYSIS_GLOBALSMODREF_H
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/IR/PassManager.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/Pass.h"
#include <list>
namespace llvm {
class CallGraph;
class Function;
/// An alias analysis result set for globals.
///
/// This focuses on handling aliasing properties of globals and interprocedural
/// function call mod/ref information.
class GlobalsAAResult : public AAResultBase {
class FunctionInfo;
const DataLayout &DL;
std::function<const TargetLibraryInfo &(Function &F)> GetTLI;
/// The globals that do not have their addresses taken.
SmallPtrSet<const GlobalValue *, 8> NonAddressTakenGlobals;
/// Are there functions with local linkage that may modify globals.
bool UnknownFunctionsWithLocalLinkage = false;
/// IndirectGlobals - The memory pointed to by this global is known to be
/// 'owned' by the global.
SmallPtrSet<const GlobalValue *, 8> IndirectGlobals;
/// AllocsForIndirectGlobals - If an instruction allocates memory for an
/// indirect global, this map indicates which one.
DenseMap<const Value *, const GlobalValue *> AllocsForIndirectGlobals;
/// For each function, keep track of what globals are modified or read.
DenseMap<const Function *, FunctionInfo> FunctionInfos;
/// A map of functions to SCC. The SCCs are described by a simple integer
/// ID that is only useful for comparing for equality (are two functions
/// in the same SCC or not?)
DenseMap<const Function *, unsigned> FunctionToSCCMap;
/// Handle to clear this analysis on deletion of values.
struct DeletionCallbackHandle final : CallbackVH {
GlobalsAAResult *GAR;
std::list<DeletionCallbackHandle>::iterator I;
DeletionCallbackHandle(GlobalsAAResult &GAR, Value *V)
: CallbackVH(V), GAR(&GAR) {}
void deleted() override;
};
/// List of callbacks for globals being tracked by this analysis. Note that
/// these objects are quite large, but we only anticipate having one per
/// global tracked by this analysis. There are numerous optimizations we
/// could perform to the memory utilization here if this becomes a problem.
std::list<DeletionCallbackHandle> Handles;
explicit GlobalsAAResult(
const DataLayout &DL,
std::function<const TargetLibraryInfo &(Function &F)> GetTLI);
friend struct RecomputeGlobalsAAPass;
public:
GlobalsAAResult(GlobalsAAResult &&Arg);
~GlobalsAAResult();
bool invalidate(Module &M, const PreservedAnalyses &PA,
ModuleAnalysisManager::Invalidator &);
static GlobalsAAResult
analyzeModule(Module &M,
std::function<const TargetLibraryInfo &(Function &F)> GetTLI,
CallGraph &CG);
//------------------------------------------------
// Implement the AliasAnalysis API
//
AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB,
AAQueryInfo &AAQI, const Instruction *CtxI);
using AAResultBase::getModRefInfo;
ModRefInfo getModRefInfo(const CallBase *Call, const MemoryLocation &Loc,
AAQueryInfo &AAQI);
using AAResultBase::getMemoryEffects;
/// getMemoryEffects - Return the behavior of the specified function if
/// called from the specified call site. The call site may be null in which
/// case the most generic behavior of this function should be returned.
MemoryEffects getMemoryEffects(const Function *F);
private:
FunctionInfo *getFunctionInfo(const Function *F);
void AnalyzeGlobals(Module &M);
void AnalyzeCallGraph(CallGraph &CG, Module &M);
bool AnalyzeUsesOfPointer(Value *V,
SmallPtrSetImpl<Function *> *Readers = nullptr,
SmallPtrSetImpl<Function *> *Writers = nullptr,
GlobalValue *OkayStoreDest = nullptr);
bool AnalyzeIndirectGlobalMemory(GlobalVariable *GV);
void CollectSCCMembership(CallGraph &CG);
bool isNonEscapingGlobalNoAlias(const GlobalValue *GV, const Value *V);
ModRefInfo getModRefInfoForArgument(const CallBase *Call,
const GlobalValue *GV, AAQueryInfo &AAQI);
};
/// Analysis pass providing a never-invalidated alias analysis result.
class GlobalsAA : public AnalysisInfoMixin<GlobalsAA> {
friend AnalysisInfoMixin<GlobalsAA>;
static AnalysisKey Key;
public:
typedef GlobalsAAResult Result;
GlobalsAAResult run(Module &M, ModuleAnalysisManager &AM);
};
struct RecomputeGlobalsAAPass : PassInfoMixin<RecomputeGlobalsAAPass> {
PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
};
/// Legacy wrapper pass to provide the GlobalsAAResult object.
class GlobalsAAWrapperPass : public ModulePass {
std::unique_ptr<GlobalsAAResult> Result;
public:
static char ID;
GlobalsAAWrapperPass();
GlobalsAAResult &getResult() { return *Result; }
const GlobalsAAResult &getResult() const { return *Result; }
bool runOnModule(Module &M) override;
bool doFinalization(Module &M) override;
void getAnalysisUsage(AnalysisUsage &AU) const override;
};
//===--------------------------------------------------------------------===//
//
// createGlobalsAAWrapperPass - This pass provides alias and mod/ref info for
// global values that do not have their addresses taken.
//
ModulePass *createGlobalsAAWrapperPass();
}
#endif
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