//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "globalsmodref-aa"
#include "llvm/Analysis/Passes.h"
-#include "llvm/Module.h"
-#include "llvm/Pass.h"
-#include "llvm/Instructions.h"
-#include "llvm/Constants.h"
-#include "llvm/DerivedTypes.h"
+#include "llvm/ADT/SCCIterator.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/CallGraph.h"
#include "llvm/Analysis/MemoryBuiltins.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/InstIterator.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
-#include "llvm/Support/InstIterator.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/SCCIterator.h"
#include <set>
using namespace llvm;
+#define DEBUG_TYPE "globalsmodref-aa"
+
STATISTIC(NumNonAddrTakenGlobalVars,
"Number of global vars without address taken");
STATISTIC(NumNonAddrTakenFunctions,"Number of functions without address taken");
public:
static char ID;
- GlobalsModRef() : ModulePass(ID) {}
+ GlobalsModRef() : ModulePass(ID) {
+ initializeGlobalsModRefPass(*PassRegistry::getPassRegistry());
+ }
+
+ bool runOnModule(Module &M) override {
+ InitializeAliasAnalysis(this, &M.getDataLayout());
+
+ // Find non-addr taken globals.
+ AnalyzeGlobals(M);
- bool runOnModule(Module &M) {
- InitializeAliasAnalysis(this); // set up super class
- AnalyzeGlobals(M); // find non-addr taken globals
- AnalyzeCallGraph(getAnalysis<CallGraph>(), M); // Propagate on CG
+ // Propagate on CG.
+ AnalyzeCallGraph(getAnalysis<CallGraphWrapperPass>().getCallGraph(), M);
return false;
}
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
AliasAnalysis::getAnalysisUsage(AU);
- AU.addRequired<CallGraph>();
+ AU.addRequired<CallGraphWrapperPass>();
AU.setPreservesAll(); // Does not transform code
}
//------------------------------------------------
// Implement the AliasAnalysis API
//
- AliasResult alias(const Location &LocA, const Location &LocB);
+ AliasResult alias(const Location &LocA, const Location &LocB) override;
ModRefResult getModRefInfo(ImmutableCallSite CS,
- const Location &Loc);
+ const Location &Loc) override;
ModRefResult getModRefInfo(ImmutableCallSite CS1,
- ImmutableCallSite CS2) {
+ ImmutableCallSite CS2) override {
return AliasAnalysis::getModRefInfo(CS1, CS2);
}
/// getModRefBehavior - 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.
- ModRefBehavior getModRefBehavior(const Function *F) {
+ ModRefBehavior getModRefBehavior(const Function *F) override {
+ ModRefBehavior Min = UnknownModRefBehavior;
+
if (FunctionRecord *FR = getFunctionInfo(F)) {
if (FR->FunctionEffect == 0)
- return DoesNotAccessMemory;
+ Min = DoesNotAccessMemory;
else if ((FR->FunctionEffect & Mod) == 0)
- return OnlyReadsMemory;
+ Min = OnlyReadsMemory;
}
- return AliasAnalysis::getModRefBehavior(F);
+
+ return ModRefBehavior(AliasAnalysis::getModRefBehavior(F) & Min);
}
/// getModRefBehavior - 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.
- ModRefBehavior getModRefBehavior(ImmutableCallSite CS) {
- const Function* F = CS.getCalledFunction();
- if (!F) return AliasAnalysis::getModRefBehavior(CS);
- if (FunctionRecord *FR = getFunctionInfo(F)) {
- if (FR->FunctionEffect == 0)
- return DoesNotAccessMemory;
- else if ((FR->FunctionEffect & Mod) == 0)
- return OnlyReadsMemory;
- }
- return AliasAnalysis::getModRefBehavior(CS);
+ ModRefBehavior getModRefBehavior(ImmutableCallSite CS) override {
+ ModRefBehavior Min = UnknownModRefBehavior;
+
+ if (const Function* F = CS.getCalledFunction())
+ if (FunctionRecord *FR = getFunctionInfo(F)) {
+ if (FR->FunctionEffect == 0)
+ Min = DoesNotAccessMemory;
+ else if ((FR->FunctionEffect & Mod) == 0)
+ Min = OnlyReadsMemory;
+ }
+
+ return ModRefBehavior(AliasAnalysis::getModRefBehavior(CS) & Min);
}
- virtual void deleteValue(Value *V);
- virtual void copyValue(Value *From, Value *To);
+ void deleteValue(Value *V) override;
+ void copyValue(Value *From, Value *To) override;
+ void addEscapingUse(Use &U) 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.
- virtual void *getAdjustedAnalysisPointer(AnalysisID PI) {
+ void *getAdjustedAnalysisPointer(AnalysisID PI) override {
if (PI == &AliasAnalysis::ID)
return (AliasAnalysis*)this;
return this;
FunctionInfo.find(F);
if (I != FunctionInfo.end())
return &I->second;
- return 0;
+ return nullptr;
}
void AnalyzeGlobals(Module &M);
void AnalyzeCallGraph(CallGraph &CG, Module &M);
bool AnalyzeUsesOfPointer(Value *V, std::vector<Function*> &Readers,
std::vector<Function*> &Writers,
- GlobalValue *OkayStoreDest = 0);
+ GlobalValue *OkayStoreDest = nullptr);
bool AnalyzeIndirectGlobalMemory(GlobalValue *GV);
};
}
char GlobalsModRef::ID = 0;
-INITIALIZE_AG_PASS(GlobalsModRef, AliasAnalysis,
+INITIALIZE_AG_PASS_BEGIN(GlobalsModRef, AliasAnalysis,
"globalsmodref-aa", "Simple mod/ref analysis for globals",
- false, true, false);
+ false, true, false)
+INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
+INITIALIZE_AG_PASS_END(GlobalsModRef, AliasAnalysis,
+ "globalsmodref-aa", "Simple mod/ref analysis for globals",
+ false, true, false)
Pass *llvm::createGlobalsModRefPass() { return new GlobalsModRef(); }
GlobalValue *OkayStoreDest) {
if (!V->getType()->isPointerTy()) return true;
- for (Value::use_iterator UI = V->use_begin(), E=V->use_end(); UI != E; ++UI) {
- User *U = *UI;
- if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
+ for (Use &U : V->uses()) {
+ User *I = U.getUser();
+ if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
Readers.push_back(LI->getParent()->getParent());
- } else if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
if (V == SI->getOperand(1)) {
Writers.push_back(SI->getParent()->getParent());
} else if (SI->getOperand(1) != OkayStoreDest) {
return true; // Storing the pointer
}
- } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(U)) {
- if (AnalyzeUsesOfPointer(GEP, Readers, Writers)) return true;
- } else if (BitCastInst *BCI = dyn_cast<BitCastInst>(U)) {
- if (AnalyzeUsesOfPointer(BCI, Readers, Writers, OkayStoreDest))
+ } else if (Operator::getOpcode(I) == Instruction::GetElementPtr) {
+ if (AnalyzeUsesOfPointer(I, Readers, Writers))
return true;
- } else if (isFreeCall(U)) {
- Writers.push_back(cast<Instruction>(U)->getParent()->getParent());
- } else if (CallInst *CI = dyn_cast<CallInst>(U)) {
- // Make sure that this is just the function being called, not that it is
- // passing into the function.
- for (unsigned i = 0, e = CI->getNumArgOperands(); i != e; ++i)
- if (CI->getArgOperand(i) == V) return true;
- } else if (InvokeInst *II = dyn_cast<InvokeInst>(U)) {
+ } else if (Operator::getOpcode(I) == Instruction::BitCast) {
+ if (AnalyzeUsesOfPointer(I, Readers, Writers, OkayStoreDest))
+ return true;
+ } else if (auto CS = CallSite(I)) {
// Make sure that this is just the function being called, not that it is
// passing into the function.
- for (unsigned i = 0, e = II->getNumArgOperands(); i != e; ++i)
- if (II->getArgOperand(i) == V) return true;
- } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) {
- if (CE->getOpcode() == Instruction::GetElementPtr ||
- CE->getOpcode() == Instruction::BitCast) {
- if (AnalyzeUsesOfPointer(CE, Readers, Writers))
- return true;
- } else {
- return true;
+ if (!CS.isCallee(&U)) {
+ // Detect calls to free.
+ if (isFreeCall(I, TLI))
+ Writers.push_back(CS->getParent()->getParent());
+ else
+ return true; // Argument of an unknown call.
}
- } else if (ICmpInst *ICI = dyn_cast<ICmpInst>(U)) {
+ } else if (ICmpInst *ICI = dyn_cast<ICmpInst>(I)) {
if (!isa<ConstantPointerNull>(ICI->getOperand(1)))
return true; // Allow comparison against null.
} else {
// Walk the user list of the global. If we find anything other than a direct
// load or store, bail out.
- for (Value::use_iterator I = GV->use_begin(), E = GV->use_end(); I != E; ++I){
- User *U = *I;
+ for (User *U : GV->users()) {
if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
// The pointer loaded from the global can only be used in simple ways:
// we allow addressing of it and loading storing to it. We do *not* allow
continue;
// Check the value being stored.
- Value *Ptr = SI->getOperand(0)->getUnderlyingObject();
-
- if (isMalloc(Ptr)) {
- // Okay, easy case.
- } else if (CallInst *CI = dyn_cast<CallInst>(Ptr)) {
- Function *F = CI->getCalledFunction();
- if (!F || !F->isDeclaration()) return false; // Too hard to analyze.
- if (F->getName() != "calloc") return false; // Not calloc.
- } else {
+ Value *Ptr = GetUnderlyingObject(SI->getOperand(0),
+ GV->getParent()->getDataLayout());
+
+ if (!isAllocLikeFn(Ptr, TLI))
return false; // Too hard to analyze.
- }
// Analyze all uses of the allocation. If any of them are used in a
// non-simple way (e.g. stored to another global) bail out.
void GlobalsModRef::AnalyzeCallGraph(CallGraph &CG, Module &M) {
// We do a bottom-up SCC traversal of the call graph. In other words, we
// visit all callees before callers (leaf-first).
- for (scc_iterator<CallGraph*> I = scc_begin(&CG), E = scc_end(&CG); I != E;
- ++I) {
- std::vector<CallGraphNode *> &SCC = *I;
+ for (scc_iterator<CallGraph*> I = scc_begin(&CG); !I.isAtEnd(); ++I) {
+ const std::vector<CallGraphNode *> &SCC = *I;
assert(!SCC.empty() && "SCC with no functions?");
if (!SCC[0]->getFunction()) {
FunctionEffect |= CalleeFR->FunctionEffect;
// Incorporate callee's effects on globals into our info.
- for (std::map<const GlobalValue*, unsigned>::iterator GI =
- CalleeFR->GlobalInfo.begin(), E = CalleeFR->GlobalInfo.end();
- GI != E; ++GI)
- FR.GlobalInfo[GI->first] |= GI->second;
+ for (const auto &G : CalleeFR->GlobalInfo)
+ FR.GlobalInfo[G.first] |= G.second;
FR.MayReadAnyGlobal |= CalleeFR->MayReadAnyGlobal;
} else {
// Can't say anything about it. However, if it is inside our SCC,
for (inst_iterator II = inst_begin(SCC[i]->getFunction()),
E = inst_end(SCC[i]->getFunction());
II != E && FunctionEffect != ModRef; ++II)
- if (isa<LoadInst>(*II)) {
+ if (LoadInst *LI = dyn_cast<LoadInst>(&*II)) {
FunctionEffect |= Ref;
- if (cast<LoadInst>(*II).isVolatile())
+ if (LI->isVolatile())
// Volatile loads may have side-effects, so mark them as writing
// memory (for example, a flag inside the processor).
FunctionEffect |= Mod;
- } else if (isa<StoreInst>(*II)) {
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(&*II)) {
FunctionEffect |= Mod;
- if (cast<StoreInst>(*II).isVolatile())
+ if (SI->isVolatile())
// Treat volatile stores as reading memory somewhere.
FunctionEffect |= Ref;
- } else if (isMalloc(&cast<Instruction>(*II)) ||
- isFreeCall(&cast<Instruction>(*II))) {
+ } else if (isAllocationFn(&*II, TLI) || isFreeCall(&*II, TLI)) {
FunctionEffect |= ModRef;
+ } else if (IntrinsicInst *Intrinsic = dyn_cast<IntrinsicInst>(&*II)) {
+ // The callgraph doesn't include intrinsic calls.
+ Function *Callee = Intrinsic->getCalledFunction();
+ ModRefBehavior Behaviour = AliasAnalysis::getModRefBehavior(Callee);
+ FunctionEffect |= (Behaviour & ModRef);
}
if ((FunctionEffect & Mod) == 0)
GlobalsModRef::alias(const Location &LocA,
const Location &LocB) {
// Get the base object these pointers point to.
- const Value *UV1 = LocA.Ptr->getUnderlyingObject();
- const Value *UV2 = LocB.Ptr->getUnderlyingObject();
+ const Value *UV1 = GetUnderlyingObject(LocA.Ptr, *DL);
+ const Value *UV2 = GetUnderlyingObject(LocB.Ptr, *DL);
// If either of the underlying values is a global, they may be non-addr-taken
// globals, which we can answer queries about.
if (GV1 || GV2) {
// If the global's address is taken, pretend we don't know it's a pointer to
// the global.
- if (GV1 && !NonAddressTakenGlobals.count(GV1)) GV1 = 0;
- if (GV2 && !NonAddressTakenGlobals.count(GV2)) GV2 = 0;
+ if (GV1 && !NonAddressTakenGlobals.count(GV1)) GV1 = nullptr;
+ if (GV2 && !NonAddressTakenGlobals.count(GV2)) GV2 = nullptr;
// If the two pointers are derived from two different non-addr-taken
// globals, or if one is and the other isn't, we know these can't alias.
// These pointers may be based on the memory owned by an indirect global. If
// so, we may be able to handle this. First check to see if the base pointer
// is a direct load from an indirect global.
- GV1 = GV2 = 0;
+ GV1 = GV2 = nullptr;
if (const LoadInst *LI = dyn_cast<LoadInst>(UV1))
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0)))
if (IndirectGlobals.count(GV))
// If we are asking for mod/ref info of a direct call with a pointer to a
// global we are tracking, return information if we have it.
+ const DataLayout &DL = CS.getCaller()->getParent()->getDataLayout();
if (const GlobalValue *GV =
- dyn_cast<GlobalValue>(Loc.Ptr->getUnderlyingObject()))
+ dyn_cast<GlobalValue>(GetUnderlyingObject(Loc.Ptr, DL)))
if (GV->hasLocalLinkage())
if (const Function *F = CS.getCalledFunction())
if (NonAddressTakenGlobals.count(GV))
void GlobalsModRef::copyValue(Value *From, Value *To) {
AliasAnalysis::copyValue(From, To);
}
+
+void GlobalsModRef::addEscapingUse(Use &U) {
+ // For the purposes of this analysis, it is conservatively correct to treat
+ // a newly escaping value equivalently to a deleted one. We could perhaps
+ // be more precise by processing the new use and attempting to update our
+ // saved analysis results to accommodate it.
+ deleteValue(U);
+
+ AliasAnalysis::addEscapingUse(U);
+}
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