#include "llvm/DerivedTypes.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/CallGraph.h"
-#include "llvm/Support/Compiler.h"
+#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/InstIterator.h"
#include "llvm/ADT/Statistic.h"
/// function in the program. Later, the entries for these functions are
/// removed if the function is found to call an external function (in which
/// case we know nothing about it.
- struct VISIBILITY_HIDDEN FunctionRecord {
+ struct FunctionRecord {
/// GlobalInfo - Maintain mod/ref info for all of the globals without
/// addresses taken that are read or written (transitively) by this
/// function.
- std::map<GlobalValue*, unsigned> GlobalInfo;
+ std::map<const GlobalValue*, unsigned> GlobalInfo;
- unsigned getInfoForGlobal(GlobalValue *GV) const {
- std::map<GlobalValue*, unsigned>::const_iterator I = GlobalInfo.find(GV);
+ /// MayReadAnyGlobal - May read global variables, but it is not known which.
+ bool MayReadAnyGlobal;
+
+ unsigned getInfoForGlobal(const GlobalValue *GV) const {
+ unsigned Effect = MayReadAnyGlobal ? AliasAnalysis::Ref : 0;
+ std::map<const GlobalValue*, unsigned>::const_iterator I =
+ GlobalInfo.find(GV);
if (I != GlobalInfo.end())
- return I->second;
- return 0;
+ Effect |= I->second;
+ return Effect;
}
/// FunctionEffect - Capture whether or not this function reads or writes to
/// ANY memory. If not, we can do a lot of aggressive analysis on it.
unsigned FunctionEffect;
- FunctionRecord() : FunctionEffect(0) {}
+ FunctionRecord() : MayReadAnyGlobal (false), FunctionEffect(0) {}
};
/// GlobalsModRef - The actual analysis pass.
- class VISIBILITY_HIDDEN GlobalsModRef
- : public ModulePass, public AliasAnalysis {
+ class GlobalsModRef : public ModulePass, public AliasAnalysis {
/// NonAddressTakenGlobals - The globals that do not have their addresses
/// taken.
- std::set<GlobalValue*> NonAddressTakenGlobals;
-
- /// ReadGlobals - The globals without addresses taken that are read by
- /// some function.
- std::set<GlobalValue*> ReadGlobals;
+ std::set<const GlobalValue*> NonAddressTakenGlobals;
/// IndirectGlobals - The memory pointed to by this global is known to be
/// 'owned' by the global.
- std::set<GlobalValue*> IndirectGlobals;
+ std::set<const GlobalValue*> IndirectGlobals;
/// AllocsForIndirectGlobals - If an instruction allocates memory for an
/// indirect global, this map indicates which one.
- std::map<Value*, GlobalValue*> AllocsForIndirectGlobals;
+ std::map<const Value*, const GlobalValue*> AllocsForIndirectGlobals;
/// FunctionInfo - For each function, keep track of what globals are
/// modified or read.
- std::map<Function*, FunctionRecord> FunctionInfo;
+ std::map<const Function*, FunctionRecord> FunctionInfo;
public:
static char ID;
- GlobalsModRef() : ModulePass(&ID) {}
+ GlobalsModRef() : ModulePass(ID) {}
bool runOnModule(Module &M) {
InitializeAliasAnalysis(this); // set up super class
//
AliasResult alias(const Value *V1, unsigned V1Size,
const Value *V2, unsigned V2Size);
- ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size);
- ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) {
- return AliasAnalysis::getModRefInfo(CS1,CS2);
+ ModRefResult getModRefInfo(ImmutableCallSite CS,
+ const Value *P, unsigned Size);
+ ModRefResult getModRefInfo(ImmutableCallSite CS1,
+ ImmutableCallSite CS2) {
+ return AliasAnalysis::getModRefInfo(CS1, CS2);
}
- bool hasNoModRefInfoForCalls() const { return false; }
/// 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.
- virtual ModRefBehavior getModRefBehavior(Function *F, CallSite CS,
- std::vector<PointerAccessInfo> *Info) {
+ ModRefBehavior getModRefBehavior(const Function *F) {
if (FunctionRecord *FR = getFunctionInfo(F)) {
if (FR->FunctionEffect == 0)
return DoesNotAccessMemory;
else if ((FR->FunctionEffect & Mod) == 0)
return OnlyReadsMemory;
}
- return AliasAnalysis::getModRefBehavior(F, CS, Info);
+ return AliasAnalysis::getModRefBehavior(F);
+ }
+
+ /// 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);
}
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(AnalysisID PI) {
+ if (PI == &AliasAnalysis::ID)
+ return (AliasAnalysis*)this;
+ return this;
+ }
+
private:
/// getFunctionInfo - Return the function info for the function, or null if
/// we don't have anything useful to say about it.
- FunctionRecord *getFunctionInfo(Function *F) {
- std::map<Function*, FunctionRecord>::iterator I = FunctionInfo.find(F);
+ FunctionRecord *getFunctionInfo(const Function *F) {
+ std::map<const Function*, FunctionRecord>::iterator I =
+ FunctionInfo.find(F);
if (I != FunctionInfo.end())
return &I->second;
return 0;
}
char GlobalsModRef::ID = 0;
-static RegisterPass<GlobalsModRef>
-X("globalsmodref-aa", "Simple mod/ref analysis for globals", false, true);
-static RegisterAnalysisGroup<AliasAnalysis> Y(X);
+INITIALIZE_AG_PASS(GlobalsModRef, AliasAnalysis,
+ "globalsmodref-aa", "Simple mod/ref analysis for globals",
+ false, true, false);
Pass *llvm::createGlobalsModRefPass() { return new GlobalsModRef(); }
-/// getUnderlyingObject - This traverses the use chain to figure out what object
-/// the specified value points to. If the value points to, or is derived from,
-/// a global object, return it.
-static Value *getUnderlyingObject(Value *V) {
- if (!isa<PointerType>(V->getType())) return V;
-
- // If we are at some type of object... return it.
- if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) return GV;
-
- // Traverse through different addressing mechanisms.
- if (Instruction *I = dyn_cast<Instruction>(V)) {
- if (isa<BitCastInst>(I) || isa<GetElementPtrInst>(I))
- return getUnderlyingObject(I->getOperand(0));
- } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
- if (CE->getOpcode() == Instruction::BitCast ||
- CE->getOpcode() == Instruction::GetElementPtr)
- return getUnderlyingObject(CE->getOperand(0));
- }
-
- // Otherwise, we don't know what this is, return it as the base pointer.
- return V;
-}
-
/// AnalyzeGlobals - Scan through the users of all of the internal
/// GlobalValue's in the program. If none of them have their "address taken"
/// (really, their address passed to something nontrivial), record this fact,
void GlobalsModRef::AnalyzeGlobals(Module &M) {
std::vector<Function*> Readers, Writers;
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
- if (I->hasInternalLinkage()) {
+ if (I->hasLocalLinkage()) {
if (!AnalyzeUsesOfPointer(I, Readers, Writers)) {
// Remember that we are tracking this global.
NonAddressTakenGlobals.insert(I);
for (Module::global_iterator I = M.global_begin(), E = M.global_end();
I != E; ++I)
- if (I->hasInternalLinkage()) {
+ if (I->hasLocalLinkage()) {
if (!AnalyzeUsesOfPointer(I, Readers, Writers)) {
// Remember that we are tracking this global, and the mod/ref fns
NonAddressTakenGlobals.insert(I);
- if (!Readers.empty())
- // Some function read this global - remember that.
- ReadGlobals.insert(I);
-
for (unsigned i = 0, e = Readers.size(); i != e; ++i)
FunctionInfo[Readers[i]].GlobalInfo[I] |= Ref;
++NumNonAddrTakenGlobalVars;
// If this global holds a pointer type, see if it is an indirect global.
- if (isa<PointerType>(I->getType()->getElementType()) &&
+ if (I->getType()->getElementType()->isPointerTy() &&
AnalyzeIndirectGlobalMemory(I))
++NumIndirectGlobalVars;
}
std::vector<Function*> &Readers,
std::vector<Function*> &Writers,
GlobalValue *OkayStoreDest) {
- if (!isa<PointerType>(V->getType())) return true;
+ if (!V->getType()->isPointerTy()) return true;
- for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI)
- if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
+ 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)) {
Readers.push_back(LI->getParent()->getParent());
- } else if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
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>(*UI)) {
+ } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(U)) {
if (AnalyzeUsesOfPointer(GEP, Readers, Writers)) return true;
- } else if (CallInst *CI = dyn_cast<CallInst>(*UI)) {
+ } else if (BitCastInst *BCI = dyn_cast<BitCastInst>(U)) {
+ if (AnalyzeUsesOfPointer(BCI, Readers, Writers, OkayStoreDest))
+ 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 = 1, e = CI->getNumOperands(); i != e; ++i)
- if (CI->getOperand(i) == V) return true;
- } else if (InvokeInst *II = dyn_cast<InvokeInst>(*UI)) {
+ 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)) {
// Make sure that this is just the function being called, not that it is
// passing into the function.
- for (unsigned i = 3, e = II->getNumOperands(); i != e; ++i)
- if (II->getOperand(i) == V) return true;
- } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(*UI)) {
+ 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))
} else {
return true;
}
- } else if (ICmpInst *ICI = dyn_cast<ICmpInst>(*UI)) {
+ } else if (ICmpInst *ICI = dyn_cast<ICmpInst>(U)) {
if (!isa<ConstantPointerNull>(ICI->getOperand(1)))
return true; // Allow comparison against null.
- } else if (FreeInst *F = dyn_cast<FreeInst>(*UI)) {
- Writers.push_back(F->getParent()->getParent());
} else {
return true;
}
+ }
+
return false;
}
// 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){
- if (LoadInst *LI = dyn_cast<LoadInst>(*I)) {
+ User *U = *I;
+ 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
// storing the loaded pointer somewhere else or passing to a function.
if (AnalyzeUsesOfPointer(LI, ReadersWriters, ReadersWriters))
return false; // Loaded pointer escapes.
// TODO: Could try some IP mod/ref of the loaded pointer.
- } else if (StoreInst *SI = dyn_cast<StoreInst>(*I)) {
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
// Storing the global itself.
if (SI->getOperand(0) == GV) return false;
continue;
// Check the value being stored.
- Value *Ptr = getUnderlyingObject(SI->getOperand(0));
+ Value *Ptr = SI->getOperand(0)->getUnderlyingObject();
- if (isa<MallocInst>(Ptr)) {
+ if (isMalloc(Ptr)) {
// Okay, easy case.
} else if (CallInst *CI = dyn_cast<CallInst>(Ptr)) {
Function *F = CI->getCalledFunction();
for (scc_iterator<CallGraph*> I = scc_begin(&CG), E = scc_end(&CG); I != E;
++I) {
std::vector<CallGraphNode *> &SCC = *I;
+ assert(!SCC.empty() && "SCC with no functions?");
- FunctionRecord *FR = 0;
- // Find a function record from the SCC (it doesn't matter which one).
- for (unsigned i = 0, e = SCC.size(); i != e; ++i)
- if (Function *F = SCC[i]->getFunction()) {
- FR = &FunctionInfo[F];
- break;
- }
-
- if (!FR)
- // Nothing to do.
+ if (!SCC[0]->getFunction()) {
+ // Calls externally - can't say anything useful. Remove any existing
+ // function records (may have been created when scanning globals).
+ for (unsigned i = 0, e = SCC.size(); i != e; ++i)
+ FunctionInfo.erase(SCC[i]->getFunction());
continue;
+ }
+
+ FunctionRecord &FR = FunctionInfo[SCC[0]->getFunction()];
bool KnowNothing = false;
unsigned FunctionEffect = 0;
// Can't do better than that!
} else if (F->onlyReadsMemory()) {
FunctionEffect |= Ref;
- // This function might call back into the module and read a global, so
- // mark all globals read somewhere as being read by this function.
- for (std::set<GlobalValue*>::iterator GI = ReadGlobals.begin(),
- E = ReadGlobals.end(); GI != E; ++GI)
- FR->GlobalInfo[*GI] |= Ref;
+ if (!F->isIntrinsic())
+ // This function might call back into the module and read a global -
+ // consider every global as possibly being read by this function.
+ FR.MayReadAnyGlobal = true;
} else {
- // Can't say anything useful.
- KnowNothing = true;
+ FunctionEffect |= ModRef;
+ // Can't say anything useful unless it's an intrinsic - they don't
+ // read or write global variables of the kind considered here.
+ KnowNothing = !F->isIntrinsic();
}
continue;
}
for (CallGraphNode::iterator CI = SCC[i]->begin(), E = SCC[i]->end();
- CI != E; ++CI)
+ CI != E && !KnowNothing; ++CI)
if (Function *Callee = CI->second->getFunction()) {
if (FunctionRecord *CalleeFR = getFunctionInfo(Callee)) {
// Propagate function effect up.
FunctionEffect |= CalleeFR->FunctionEffect;
// Incorporate callee's effects on globals into our info.
- for (std::map<GlobalValue*, unsigned>::iterator GI =
+ for (std::map<const GlobalValue*, unsigned>::iterator GI =
CalleeFR->GlobalInfo.begin(), E = CalleeFR->GlobalInfo.end();
GI != E; ++GI)
- FR->GlobalInfo[GI->first] |= GI->second;
+ FR.GlobalInfo[GI->first] |= GI->second;
+ FR.MayReadAnyGlobal |= CalleeFR->MayReadAnyGlobal;
} else {
// Can't say anything about it. However, if it is inside our SCC,
// then nothing needs to be done.
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 (isa<LoadInst>(*II)) {
FunctionEffect |= Ref;
- else if (isa<StoreInst>(*II))
+ if (cast<LoadInst>(*II).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)) {
FunctionEffect |= Mod;
- else if (isa<MallocInst>(*II) || isa<FreeInst>(*II))
+ if (cast<StoreInst>(*II).isVolatile())
+ // Treat volatile stores as reading memory somewhere.
+ FunctionEffect |= Ref;
+ } else if (isMalloc(&cast<Instruction>(*II)) ||
+ isFreeCall(&cast<Instruction>(*II))) {
FunctionEffect |= ModRef;
+ }
if ((FunctionEffect & Mod) == 0)
++NumReadMemFunctions;
if (FunctionEffect == 0)
++NumNoMemFunctions;
- FR->FunctionEffect = FunctionEffect;
+ FR.FunctionEffect = FunctionEffect;
// Finally, now that we know the full effect on this SCC, clone the
// information to each function in the SCC.
for (unsigned i = 1, e = SCC.size(); i != e; ++i)
- FunctionInfo[SCC[i]->getFunction()] = *FR;
+ FunctionInfo[SCC[i]->getFunction()] = FR;
}
}
GlobalsModRef::alias(const Value *V1, unsigned V1Size,
const Value *V2, unsigned V2Size) {
// Get the base object these pointers point to.
- Value *UV1 = getUnderlyingObject(const_cast<Value*>(V1));
- Value *UV2 = getUnderlyingObject(const_cast<Value*>(V2));
+ const Value *UV1 = V1->getUnderlyingObject();
+ const Value *UV2 = V2->getUnderlyingObject();
// If either of the underlying values is a global, they may be non-addr-taken
// globals, which we can answer queries about.
- GlobalValue *GV1 = dyn_cast<GlobalValue>(UV1);
- GlobalValue *GV2 = dyn_cast<GlobalValue>(UV2);
+ const GlobalValue *GV1 = dyn_cast<GlobalValue>(UV1);
+ const GlobalValue *GV2 = dyn_cast<GlobalValue>(UV2);
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 the the two pointers are derived from two different non-addr-taken
+ // 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.
if ((GV1 || GV2) && GV1 != GV2)
return NoAlias;
// 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;
- if (LoadInst *LI = dyn_cast<LoadInst>(UV1))
+ if (const LoadInst *LI = dyn_cast<LoadInst>(UV1))
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0)))
if (IndirectGlobals.count(GV))
GV1 = GV;
- if (LoadInst *LI = dyn_cast<LoadInst>(UV2))
- if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0)))
+ if (const LoadInst *LI = dyn_cast<LoadInst>(UV2))
+ if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0)))
if (IndirectGlobals.count(GV))
GV2 = GV;
}
AliasAnalysis::ModRefResult
-GlobalsModRef::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
+GlobalsModRef::getModRefInfo(ImmutableCallSite CS,
+ const Value *P, unsigned Size) {
unsigned Known = ModRef;
// 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.
- if (GlobalValue *GV = dyn_cast<GlobalValue>(getUnderlyingObject(P)))
- if (GV->hasInternalLinkage())
- if (Function *F = CS.getCalledFunction())
+ if (const GlobalValue *GV = dyn_cast<GlobalValue>(P->getUnderlyingObject()))
+ if (GV->hasLocalLinkage())
+ if (const Function *F = CS.getCalledFunction())
if (NonAddressTakenGlobals.count(GV))
- if (FunctionRecord *FR = getFunctionInfo(F))
+ if (const FunctionRecord *FR = getFunctionInfo(F))
Known = FR->getInfoForGlobal(GV);
if (Known == NoModRef)
// any AllocRelatedValues for it.
if (IndirectGlobals.erase(GV)) {
// Remove any entries in AllocsForIndirectGlobals for this global.
- for (std::map<Value*, GlobalValue*>::iterator
+ for (std::map<const Value*, const GlobalValue*>::iterator
I = AllocsForIndirectGlobals.begin(),
E = AllocsForIndirectGlobals.end(); I != E; ) {
if (I->second == GV) {
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