diff options
Diffstat (limited to 'contrib/llvm/lib/Transforms/IPO/GlobalOpt.cpp')
| -rw-r--r-- | contrib/llvm/lib/Transforms/IPO/GlobalOpt.cpp | 830 |
1 files changed, 491 insertions, 339 deletions
diff --git a/contrib/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/contrib/llvm/lib/Transforms/IPO/GlobalOpt.cpp index a77af54..d4cb712 100644 --- a/contrib/llvm/lib/Transforms/IPO/GlobalOpt.cpp +++ b/contrib/llvm/lib/Transforms/IPO/GlobalOpt.cpp @@ -40,6 +40,7 @@ using namespace llvm; STATISTIC(NumMarked , "Number of globals marked constant"); +STATISTIC(NumUnnamed , "Number of globals marked unnamed_addr"); STATISTIC(NumSRA , "Number of aggregate globals broken into scalars"); STATISTIC(NumHeapSRA , "Number of heap objects SRA'd"); STATISTIC(NumSubstitute,"Number of globals with initializers stored into them"); @@ -55,11 +56,14 @@ STATISTIC(NumAliasesResolved, "Number of global aliases resolved"); STATISTIC(NumAliasesRemoved, "Number of global aliases eliminated"); namespace { + struct GlobalStatus; struct GlobalOpt : public ModulePass { virtual void getAnalysisUsage(AnalysisUsage &AU) const { } static char ID; // Pass identification, replacement for typeid - GlobalOpt() : ModulePass(ID) {} + GlobalOpt() : ModulePass(ID) { + initializeGlobalOptPass(*PassRegistry::getPassRegistry()); + } bool runOnModule(Module &M); @@ -69,13 +73,16 @@ namespace { bool OptimizeGlobalVars(Module &M); bool OptimizeGlobalAliases(Module &M); bool OptimizeGlobalCtorsList(GlobalVariable *&GCL); - bool ProcessInternalGlobal(GlobalVariable *GV,Module::global_iterator &GVI); + bool ProcessGlobal(GlobalVariable *GV,Module::global_iterator &GVI); + bool ProcessInternalGlobal(GlobalVariable *GV,Module::global_iterator &GVI, + const SmallPtrSet<const PHINode*, 16> &PHIUsers, + const GlobalStatus &GS); }; } char GlobalOpt::ID = 0; INITIALIZE_PASS(GlobalOpt, "globalopt", - "Global Variable Optimizer", false, false); + "Global Variable Optimizer", false, false) ModulePass *llvm::createGlobalOptimizerPass() { return new GlobalOpt(); } @@ -85,6 +92,9 @@ namespace { /// about it. If we find out that the address of the global is taken, none of /// this info will be accurate. struct GlobalStatus { + /// isCompared - True if the global's address is used in a comparison. + bool isCompared; + /// isLoaded - True if the global is ever loaded. If the global isn't ever /// loaded it can be deleted. bool isLoaded; @@ -129,10 +139,11 @@ struct GlobalStatus { /// HasPHIUser - Set to true if this global has a user that is a PHI node. bool HasPHIUser; - - GlobalStatus() : isLoaded(false), StoredType(NotStored), StoredOnceValue(0), - AccessingFunction(0), HasMultipleAccessingFunctions(false), - HasNonInstructionUser(false), HasPHIUser(false) {} + + GlobalStatus() : isCompared(false), isLoaded(false), StoredType(NotStored), + StoredOnceValue(0), AccessingFunction(0), + HasMultipleAccessingFunctions(false), HasNonInstructionUser(false), + HasPHIUser(false) {} }; } @@ -165,6 +176,11 @@ static bool AnalyzeGlobal(const Value *V, GlobalStatus &GS, const User *U = *UI; if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) { GS.HasNonInstructionUser = true; + + // If the result of the constantexpr isn't pointer type, then we won't + // know to expect it in various places. Just reject early. + if (!isa<PointerType>(CE->getType())) return true; + if (AnalyzeGlobal(CE, GS, PHIUsers)) return true; } else if (const Instruction *I = dyn_cast<Instruction>(U)) { if (!GS.HasMultipleAccessingFunctions) { @@ -221,7 +237,7 @@ static bool AnalyzeGlobal(const Value *V, GlobalStatus &GS, if (AnalyzeGlobal(I, GS, PHIUsers)) return true; GS.HasPHIUser = true; } else if (isa<CmpInst>(I)) { - // Nothing to analyse. + GS.isCompared = true; } else if (isa<MemTransferInst>(I)) { const MemTransferInst *MTI = cast<MemTransferInst>(I); if (MTI->getArgOperand(0) == V) @@ -308,7 +324,7 @@ static bool CleanupConstantGlobalUsers(Value *V, Constant *Init) { if (Init) SubInit = ConstantFoldLoadThroughGEPConstantExpr(Init, CE); Changed |= CleanupConstantGlobalUsers(CE, SubInit); - } else if (CE->getOpcode() == Instruction::BitCast && + } else if (CE->getOpcode() == Instruction::BitCast && CE->getType()->isPointerTy()) { // Pointer cast, delete any stores and memsets to the global. Changed |= CleanupConstantGlobalUsers(CE, 0); @@ -324,7 +340,7 @@ static bool CleanupConstantGlobalUsers(Value *V, Constant *Init) { // and will invalidate our notion of what Init is. Constant *SubInit = 0; if (!isa<ConstantExpr>(GEP->getOperand(0))) { - ConstantExpr *CE = + ConstantExpr *CE = dyn_cast_or_null<ConstantExpr>(ConstantFoldInstruction(GEP)); if (Init && CE && CE->getOpcode() == Instruction::GetElementPtr) SubInit = ConstantFoldLoadThroughGEPConstantExpr(Init, CE); @@ -361,7 +377,7 @@ static bool isSafeSROAElementUse(Value *V) { // We might have a dead and dangling constant hanging off of here. if (Constant *C = dyn_cast<Constant>(V)) return SafeToDestroyConstant(C); - + Instruction *I = dyn_cast<Instruction>(V); if (!I) return false; @@ -371,15 +387,15 @@ static bool isSafeSROAElementUse(Value *V) { // Stores *to* the pointer are ok. if (StoreInst *SI = dyn_cast<StoreInst>(I)) return SI->getOperand(0) != V; - + // Otherwise, it must be a GEP. GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I); if (GEPI == 0) return false; - + if (GEPI->getNumOperands() < 3 || !isa<Constant>(GEPI->getOperand(1)) || !cast<Constant>(GEPI->getOperand(1))->isNullValue()) return false; - + for (Value::use_iterator I = GEPI->use_begin(), E = GEPI->use_end(); I != E; ++I) if (!isSafeSROAElementUse(*I)) @@ -393,11 +409,11 @@ static bool isSafeSROAElementUse(Value *V) { /// static bool IsUserOfGlobalSafeForSRA(User *U, GlobalValue *GV) { // The user of the global must be a GEP Inst or a ConstantExpr GEP. - if (!isa<GetElementPtrInst>(U) && - (!isa<ConstantExpr>(U) || + if (!isa<GetElementPtrInst>(U) && + (!isa<ConstantExpr>(U) || cast<ConstantExpr>(U)->getOpcode() != Instruction::GetElementPtr)) return false; - + // Check to see if this ConstantExpr GEP is SRA'able. In particular, we // don't like < 3 operand CE's, and we don't like non-constant integer // indices. This enforces that all uses are 'gep GV, 0, C, ...' for some @@ -409,18 +425,18 @@ static bool IsUserOfGlobalSafeForSRA(User *U, GlobalValue *GV) { gep_type_iterator GEPI = gep_type_begin(U), E = gep_type_end(U); ++GEPI; // Skip over the pointer index. - + // If this is a use of an array allocation, do a bit more checking for sanity. if (const ArrayType *AT = dyn_cast<ArrayType>(*GEPI)) { uint64_t NumElements = AT->getNumElements(); ConstantInt *Idx = cast<ConstantInt>(U->getOperand(2)); - + // Check to make sure that index falls within the array. If not, // something funny is going on, so we won't do the optimization. // if (Idx->getZExtValue() >= NumElements) return false; - + // We cannot scalar repl this level of the array unless any array // sub-indices are in-range constants. In particular, consider: // A[0][i]. We cannot know that the user isn't doing invalid things like @@ -441,7 +457,7 @@ static bool IsUserOfGlobalSafeForSRA(User *U, GlobalValue *GV) { "Indexed GEP type is not array, vector, or struct!"); continue; } - + ConstantInt *IdxVal = dyn_cast<ConstantInt>(GEPI.getOperand()); if (!IdxVal || IdxVal->getZExtValue() >= NumElements) return false; @@ -465,7 +481,7 @@ static bool GlobalUsersSafeToSRA(GlobalValue *GV) { } return true; } - + /// SRAGlobal - Perform scalar replacement of aggregates on the specified global /// variable. This opens the door for other optimizations by exposing the @@ -476,7 +492,7 @@ static GlobalVariable *SRAGlobal(GlobalVariable *GV, const TargetData &TD) { // Make sure this global only has simple uses that we can SRA. if (!GlobalUsersSafeToSRA(GV)) return 0; - + assert(GV->hasLocalLinkage() && !GV->isConstant()); Constant *Init = GV->getInitializer(); const Type *Ty = Init->getType(); @@ -488,7 +504,7 @@ static GlobalVariable *SRAGlobal(GlobalVariable *GV, const TargetData &TD) { unsigned StartAlignment = GV->getAlignment(); if (StartAlignment == 0) StartAlignment = TD.getABITypeAlignment(GV->getType()); - + if (const StructType *STy = dyn_cast<StructType>(Ty)) { NewGlobals.reserve(STy->getNumElements()); const StructLayout &Layout = *TD.getStructLayout(STy); @@ -503,7 +519,7 @@ static GlobalVariable *SRAGlobal(GlobalVariable *GV, const TargetData &TD) { GV->getType()->getAddressSpace()); Globals.insert(GV, NGV); NewGlobals.push_back(NGV); - + // Calculate the known alignment of the field. If the original aggregate // had 256 byte alignment for example, something might depend on that: // propagate info to each field. @@ -522,7 +538,7 @@ static GlobalVariable *SRAGlobal(GlobalVariable *GV, const TargetData &TD) { if (NumElements > 16 && GV->hasNUsesOrMore(16)) return 0; // It's not worth it. NewGlobals.reserve(NumElements); - + uint64_t EltSize = TD.getTypeAllocSize(STy->getElementType()); unsigned EltAlign = TD.getABITypeAlignment(STy->getElementType()); for (unsigned i = 0, e = NumElements; i != e; ++i) { @@ -537,7 +553,7 @@ static GlobalVariable *SRAGlobal(GlobalVariable *GV, const TargetData &TD) { GV->getType()->getAddressSpace()); Globals.insert(GV, NGV); NewGlobals.push_back(NGV); - + // Calculate the known alignment of the field. If the original aggregate // had 256 byte alignment for example, something might depend on that: // propagate info to each field. @@ -549,7 +565,7 @@ static GlobalVariable *SRAGlobal(GlobalVariable *GV, const TargetData &TD) { if (NewGlobals.empty()) return 0; - + DEBUG(dbgs() << "PERFORMING GLOBAL SRA ON: " << *GV); Constant *NullInt =Constant::getNullValue(Type::getInt32Ty(GV->getContext())); @@ -615,7 +631,7 @@ static GlobalVariable *SRAGlobal(GlobalVariable *GV, const TargetData &TD) { } /// AllUsesOfValueWillTrapIfNull - Return true if all users of the specified -/// value will trap if the value is dynamically null. PHIs keeps track of any +/// value will trap if the value is dynamically null. PHIs keeps track of any /// phi nodes we've seen to avoid reprocessing them. static bool AllUsesOfValueWillTrapIfNull(const Value *V, SmallPtrSet<const PHINode*, 8> &PHIs) { @@ -757,7 +773,7 @@ static bool OptimizeAwayTrappingUsesOfLoads(GlobalVariable *GV, Constant *LV) { // Keep track of whether we are able to remove all the uses of the global // other than the store that defines it. bool AllNonStoreUsesGone = true; - + // Replace all uses of loads with uses of uses of the stored value. for (Value::use_iterator GUI = GV->use_begin(), E = GV->use_end(); GUI != E;){ User *GlobalUser = *GUI++; @@ -830,7 +846,7 @@ static GlobalVariable *OptimizeGlobalAddressOfMalloc(GlobalVariable *GV, ConstantInt *NElements, TargetData* TD) { DEBUG(errs() << "PROMOTING GLOBAL: " << *GV << " CALL = " << *CI << '\n'); - + const Type *GlobalType; if (NElements->getZExtValue() == 1) GlobalType = AllocTy; @@ -840,14 +856,14 @@ static GlobalVariable *OptimizeGlobalAddressOfMalloc(GlobalVariable *GV, // Create the new global variable. The contents of the malloc'd memory is // undefined, so initialize with an undef value. - GlobalVariable *NewGV = new GlobalVariable(*GV->getParent(), + GlobalVariable *NewGV = new GlobalVariable(*GV->getParent(), GlobalType, false, GlobalValue::InternalLinkage, UndefValue::get(GlobalType), GV->getName()+".body", GV, GV->isThreadLocal()); - + // If there are bitcast users of the malloc (which is typical, usually we have // a malloc + bitcast) then replace them with uses of the new global. Update // other users to use the global as well. @@ -867,10 +883,10 @@ static GlobalVariable *OptimizeGlobalAddressOfMalloc(GlobalVariable *GV, User->replaceUsesOfWith(CI, TheBC); } } - + Constant *RepValue = NewGV; if (NewGV->getType() != GV->getType()->getElementType()) - RepValue = ConstantExpr::getBitCast(RepValue, + RepValue = ConstantExpr::getBitCast(RepValue, GV->getType()->getElementType()); // If there is a comparison against null, we will insert a global bool to @@ -890,7 +906,7 @@ static GlobalVariable *OptimizeGlobalAddressOfMalloc(GlobalVariable *GV, SI->eraseFromParent(); continue; } - + LoadInst *LI = cast<LoadInst>(GV->use_back()); while (!LI->use_empty()) { Use &LoadUse = LI->use_begin().getUse(); @@ -898,7 +914,7 @@ static GlobalVariable *OptimizeGlobalAddressOfMalloc(GlobalVariable *GV, LoadUse = RepValue; continue; } - + ICmpInst *ICI = cast<ICmpInst>(LoadUse.getUser()); // Replace the cmp X, 0 with a use of the bool value. Value *LV = new LoadInst(InitBool, InitBool->getName()+".val", ICI); @@ -963,20 +979,20 @@ static bool ValueIsOnlyUsedLocallyOrStoredToOneGlobal(const Instruction *V, if (isa<LoadInst>(Inst) || isa<CmpInst>(Inst)) { continue; // Fine, ignore. } - + if (const StoreInst *SI = dyn_cast<StoreInst>(Inst)) { if (SI->getOperand(0) == V && SI->getOperand(1) != GV) return false; // Storing the pointer itself... bad. continue; // Otherwise, storing through it, or storing into GV... fine. } - + // Must index into the array and into the struct. if (isa<GetElementPtrInst>(Inst) && Inst->getNumOperands() >= 3) { if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(Inst, GV, PHIs)) return false; continue; } - + if (const PHINode *PN = dyn_cast<PHINode>(Inst)) { // PHIs are ok if all uses are ok. Don't infinitely recurse through PHI // cycles. @@ -985,13 +1001,13 @@ static bool ValueIsOnlyUsedLocallyOrStoredToOneGlobal(const Instruction *V, return false; continue; } - + if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Inst)) { if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(BCI, GV, PHIs)) return false; continue; } - + return false; } return true; @@ -1000,9 +1016,9 @@ static bool ValueIsOnlyUsedLocallyOrStoredToOneGlobal(const Instruction *V, /// ReplaceUsesOfMallocWithGlobal - The Alloc pointer is stored into GV /// somewhere. Transform all uses of the allocation into loads from the /// global and uses of the resultant pointer. Further, delete the store into -/// GV. This assumes that these value pass the +/// GV. This assumes that these value pass the /// 'ValueIsOnlyUsedLocallyOrStoredToOneGlobal' predicate. -static void ReplaceUsesOfMallocWithGlobal(Instruction *Alloc, +static void ReplaceUsesOfMallocWithGlobal(Instruction *Alloc, GlobalVariable *GV) { while (!Alloc->use_empty()) { Instruction *U = cast<Instruction>(*Alloc->use_begin()); @@ -1035,7 +1051,7 @@ static void ReplaceUsesOfMallocWithGlobal(Instruction *Alloc, continue; } } - + // Insert a load from the global, and use it instead of the malloc. Value *NL = new LoadInst(GV, GV->getName()+".val", InsertPt); U->replaceUsesOfWith(Alloc, NL); @@ -1053,24 +1069,24 @@ static bool LoadUsesSimpleEnoughForHeapSRA(const Value *V, for (Value::const_use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI) { const Instruction *User = cast<Instruction>(*UI); - + // Comparison against null is ok. if (const ICmpInst *ICI = dyn_cast<ICmpInst>(User)) { if (!isa<ConstantPointerNull>(ICI->getOperand(1))) return false; continue; } - + // getelementptr is also ok, but only a simple form. if (const GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User)) { // Must index into the array and into the struct. if (GEPI->getNumOperands() < 3) return false; - + // Otherwise the GEP is ok. continue; } - + if (const PHINode *PN = dyn_cast<PHINode>(User)) { if (!LoadUsingPHIsPerLoad.insert(PN)) // This means some phi nodes are dependent on each other. @@ -1079,19 +1095,19 @@ static bool LoadUsesSimpleEnoughForHeapSRA(const Value *V, if (!LoadUsingPHIs.insert(PN)) // If we have already analyzed this PHI, then it is safe. continue; - + // Make sure all uses of the PHI are simple enough to transform. if (!LoadUsesSimpleEnoughForHeapSRA(PN, LoadUsingPHIs, LoadUsingPHIsPerLoad)) return false; - + continue; } - + // Otherwise we don't know what this is, not ok. return false; } - + return true; } @@ -1110,10 +1126,10 @@ static bool AllGlobalLoadUsesSimpleEnoughForHeapSRA(const GlobalVariable *GV, return false; LoadUsingPHIsPerLoad.clear(); } - + // If we reach here, we know that all uses of the loads and transitive uses // (through PHI nodes) are simple enough to transform. However, we don't know - // that all inputs the to the PHI nodes are in the same equivalence sets. + // that all inputs the to the PHI nodes are in the same equivalence sets. // Check to verify that all operands of the PHIs are either PHIS that can be // transformed, loads from GV, or MI itself. for (SmallPtrSet<const PHINode*, 32>::const_iterator I = LoadUsingPHIs.begin() @@ -1121,29 +1137,29 @@ static bool AllGlobalLoadUsesSimpleEnoughForHeapSRA(const GlobalVariable *GV, const PHINode *PN = *I; for (unsigned op = 0, e = PN->getNumIncomingValues(); op != e; ++op) { Value *InVal = PN->getIncomingValue(op); - + // PHI of the stored value itself is ok. if (InVal == StoredVal) continue; - + if (const PHINode *InPN = dyn_cast<PHINode>(InVal)) { // One of the PHIs in our set is (optimistically) ok. if (LoadUsingPHIs.count(InPN)) continue; return false; } - + // Load from GV is ok. if (const LoadInst *LI = dyn_cast<LoadInst>(InVal)) if (LI->getOperand(0) == GV) continue; - + // UNDEF? NULL? - + // Anything else is rejected. return false; } } - + return true; } @@ -1151,15 +1167,15 @@ static Value *GetHeapSROAValue(Value *V, unsigned FieldNo, DenseMap<Value*, std::vector<Value*> > &InsertedScalarizedValues, std::vector<std::pair<PHINode*, unsigned> > &PHIsToRewrite) { std::vector<Value*> &FieldVals = InsertedScalarizedValues[V]; - + if (FieldNo >= FieldVals.size()) FieldVals.resize(FieldNo+1); - + // If we already have this value, just reuse the previously scalarized // version. if (Value *FieldVal = FieldVals[FieldNo]) return FieldVal; - + // Depending on what instruction this is, we have several cases. Value *Result; if (LoadInst *LI = dyn_cast<LoadInst>(V)) { @@ -1172,9 +1188,9 @@ static Value *GetHeapSROAValue(Value *V, unsigned FieldNo, } else if (PHINode *PN = dyn_cast<PHINode>(V)) { // PN's type is pointer to struct. Make a new PHI of pointer to struct // field. - const StructType *ST = + const StructType *ST = cast<StructType>(cast<PointerType>(PN->getType())->getElementType()); - + Result = PHINode::Create(PointerType::getUnqual(ST->getElementType(FieldNo)), PN->getName()+".f"+Twine(FieldNo), PN); @@ -1183,13 +1199,13 @@ static Value *GetHeapSROAValue(Value *V, unsigned FieldNo, llvm_unreachable("Unknown usable value"); Result = 0; } - + return FieldVals[FieldNo] = Result; } /// RewriteHeapSROALoadUser - Given a load instruction and a value derived from /// the load, rewrite the derived value to use the HeapSRoA'd load. -static void RewriteHeapSROALoadUser(Instruction *LoadUser, +static void RewriteHeapSROALoadUser(Instruction *LoadUser, DenseMap<Value*, std::vector<Value*> > &InsertedScalarizedValues, std::vector<std::pair<PHINode*, unsigned> > &PHIsToRewrite) { // If this is a comparison against null, handle it. @@ -1199,30 +1215,30 @@ static void RewriteHeapSROALoadUser(Instruction *LoadUser, // field. Value *NPtr = GetHeapSROAValue(SCI->getOperand(0), 0, InsertedScalarizedValues, PHIsToRewrite); - + Value *New = new ICmpInst(SCI, SCI->getPredicate(), NPtr, - Constant::getNullValue(NPtr->getType()), + Constant::getNullValue(NPtr->getType()), SCI->getName()); SCI->replaceAllUsesWith(New); SCI->eraseFromParent(); return; } - + // Handle 'getelementptr Ptr, Idx, i32 FieldNo ...' if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(LoadUser)) { assert(GEPI->getNumOperands() >= 3 && isa<ConstantInt>(GEPI->getOperand(2)) && "Unexpected GEPI!"); - + // Load the pointer for this field. unsigned FieldNo = cast<ConstantInt>(GEPI->getOperand(2))->getZExtValue(); Value *NewPtr = GetHeapSROAValue(GEPI->getOperand(0), FieldNo, InsertedScalarizedValues, PHIsToRewrite); - + // Create the new GEP idx vector. SmallVector<Value*, 8> GEPIdx; GEPIdx.push_back(GEPI->getOperand(1)); GEPIdx.append(GEPI->op_begin()+3, GEPI->op_end()); - + Value *NGEPI = GetElementPtrInst::Create(NewPtr, GEPIdx.begin(), GEPIdx.end(), GEPI->getName(), GEPI); @@ -1243,7 +1259,7 @@ static void RewriteHeapSROALoadUser(Instruction *LoadUser, tie(InsertPos, Inserted) = InsertedScalarizedValues.insert(std::make_pair(PN, std::vector<Value*>())); if (!Inserted) return; - + // If this is the first time we've seen this PHI, recursively process all // users. for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end(); UI != E; ) { @@ -1256,7 +1272,7 @@ static void RewriteHeapSROALoadUser(Instruction *LoadUser, /// is a value loaded from the global. Eliminate all uses of Ptr, making them /// use FieldGlobals instead. All uses of loaded values satisfy /// AllGlobalLoadUsesSimpleEnoughForHeapSRA. -static void RewriteUsesOfLoadForHeapSRoA(LoadInst *Load, +static void RewriteUsesOfLoadForHeapSRoA(LoadInst *Load, DenseMap<Value*, std::vector<Value*> > &InsertedScalarizedValues, std::vector<std::pair<PHINode*, unsigned> > &PHIsToRewrite) { for (Value::use_iterator UI = Load->use_begin(), E = Load->use_end(); @@ -1264,7 +1280,7 @@ static void RewriteUsesOfLoadForHeapSRoA(LoadInst *Load, Instruction *User = cast<Instruction>(*UI++); RewriteHeapSROALoadUser(User, InsertedScalarizedValues, PHIsToRewrite); } - + if (Load->use_empty()) { Load->eraseFromParent(); InsertedScalarizedValues.erase(Load); @@ -1289,11 +1305,11 @@ static GlobalVariable *PerformHeapAllocSRoA(GlobalVariable *GV, CallInst *CI, // new mallocs at the same place as CI, and N globals. std::vector<Value*> FieldGlobals; std::vector<Value*> FieldMallocs; - + for (unsigned FieldNo = 0, e = STy->getNumElements(); FieldNo != e;++FieldNo){ const Type *FieldTy = STy->getElementType(FieldNo); const PointerType *PFieldTy = PointerType::getUnqual(FieldTy); - + GlobalVariable *NGV = new GlobalVariable(*GV->getParent(), PFieldTy, false, GlobalValue::InternalLinkage, @@ -1301,7 +1317,7 @@ static GlobalVariable *PerformHeapAllocSRoA(GlobalVariable *GV, CallInst *CI, GV->getName() + ".f" + Twine(FieldNo), GV, GV->isThreadLocal()); FieldGlobals.push_back(NGV); - + unsigned TypeSize = TD->getTypeAllocSize(FieldTy); if (const StructType *ST = dyn_cast<StructType>(FieldTy)) TypeSize = TD->getStructLayout(ST)->getSizeInBytes(); @@ -1313,7 +1329,7 @@ static GlobalVariable *PerformHeapAllocSRoA(GlobalVariable *GV, CallInst *CI, FieldMallocs.push_back(NMI); new StoreInst(NMI, NGV, CI); } - + // The tricky aspect of this transformation is handling the case when malloc // fails. In the original code, malloc failing would set the result pointer // of malloc to null. In this case, some mallocs could succeed and others @@ -1340,23 +1356,23 @@ static GlobalVariable *PerformHeapAllocSRoA(GlobalVariable *GV, CallInst *CI, // Split the basic block at the old malloc. BasicBlock *OrigBB = CI->getParent(); BasicBlock *ContBB = OrigBB->splitBasicBlock(CI, "malloc_cont"); - + // Create the block to check the first condition. Put all these blocks at the // end of the function as they are unlikely to be executed. BasicBlock *NullPtrBlock = BasicBlock::Create(OrigBB->getContext(), "malloc_ret_null", OrigBB->getParent()); - + // Remove the uncond branch from OrigBB to ContBB, turning it into a cond // branch on RunningOr. OrigBB->getTerminator()->eraseFromParent(); BranchInst::Create(NullPtrBlock, ContBB, RunningOr, OrigBB); - + // Within the NullPtrBlock, we need to emit a comparison and branch for each // pointer, because some may be null while others are not. for (unsigned i = 0, e = FieldGlobals.size(); i != e; ++i) { Value *GVVal = new LoadInst(FieldGlobals[i], "tmp", NullPtrBlock); - Value *Cmp = new ICmpInst(*NullPtrBlock, ICmpInst::ICMP_NE, GVVal, + Value *Cmp = new ICmpInst(*NullPtrBlock, ICmpInst::ICMP_NE, GVVal, Constant::getNullValue(GVVal->getType()), "tmp"); BasicBlock *FreeBlock = BasicBlock::Create(Cmp->getContext(), "free_it", @@ -1371,10 +1387,10 @@ static GlobalVariable *PerformHeapAllocSRoA(GlobalVariable *GV, CallInst *CI, new StoreInst(Constant::getNullValue(GVVal->getType()), FieldGlobals[i], FreeBlock); BranchInst::Create(NextBlock, FreeBlock); - + NullPtrBlock = NextBlock; } - + BranchInst::Create(ContBB, NullPtrBlock); // CI is no longer needed, remove it. @@ -1385,25 +1401,25 @@ static GlobalVariable *PerformHeapAllocSRoA(GlobalVariable *GV, CallInst *CI, /// inserted for a given load. DenseMap<Value*, std::vector<Value*> > InsertedScalarizedValues; InsertedScalarizedValues[GV] = FieldGlobals; - + std::vector<std::pair<PHINode*, unsigned> > PHIsToRewrite; - + // Okay, the malloc site is completely handled. All of the uses of GV are now // loads, and all uses of those loads are simple. Rewrite them to use loads // of the per-field globals instead. for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end(); UI != E;) { Instruction *User = cast<Instruction>(*UI++); - + if (LoadInst *LI = dyn_cast<LoadInst>(User)) { RewriteUsesOfLoadForHeapSRoA(LI, InsertedScalarizedValues, PHIsToRewrite); continue; } - + // Must be a store of null. StoreInst *SI = cast<StoreInst>(User); assert(isa<ConstantPointerNull>(SI->getOperand(0)) && "Unexpected heap-sra user!"); - + // Insert a store of null into each global. for (unsigned i = 0, e = FieldGlobals.size(); i != e; ++i) { const PointerType *PT = cast<PointerType>(FieldGlobals[i]->getType()); @@ -1430,7 +1446,7 @@ static GlobalVariable *PerformHeapAllocSRoA(GlobalVariable *GV, CallInst *CI, FieldPN->addIncoming(InVal, PN->getIncomingBlock(i)); } } - + // Drop all inter-phi links and any loads that made it this far. for (DenseMap<Value*, std::vector<Value*> >::iterator I = InsertedScalarizedValues.begin(), E = InsertedScalarizedValues.end(); @@ -1440,7 +1456,7 @@ static GlobalVariable *PerformHeapAllocSRoA(GlobalVariable *GV, CallInst *CI, else if (LoadInst *LI = dyn_cast<LoadInst>(I->first)) LI->dropAllReferences(); } - + // Delete all the phis and loads now that inter-references are dead. for (DenseMap<Value*, std::vector<Value*> >::iterator I = InsertedScalarizedValues.begin(), E = InsertedScalarizedValues.end(); @@ -1450,7 +1466,7 @@ static GlobalVariable *PerformHeapAllocSRoA(GlobalVariable *GV, CallInst *CI, else if (LoadInst *LI = dyn_cast<LoadInst>(I->first)) LI->eraseFromParent(); } - + // The old global is now dead, remove it. GV->eraseFromParent(); @@ -1468,7 +1484,7 @@ static bool TryToOptimizeStoreOfMallocToGlobal(GlobalVariable *GV, TargetData *TD) { if (!TD) return false; - + // If this is a malloc of an abstract type, don't touch it. if (!AllocTy->isSized()) return false; @@ -1508,7 +1524,7 @@ static bool TryToOptimizeStoreOfMallocToGlobal(GlobalVariable *GV, GVI = OptimizeGlobalAddressOfMalloc(GV, CI, AllocTy, NElements, TD); return true; } - + // If the allocation is an array of structures, consider transforming this // into multiple malloc'd arrays, one for each field. This is basically // SRoA for malloc'd memory. @@ -1544,13 +1560,13 @@ static bool TryToOptimizeStoreOfMallocToGlobal(GlobalVariable *GV, CI = dyn_cast<BitCastInst>(Malloc) ? extractMallocCallFromBitCast(Malloc) : cast<CallInst>(Malloc); } - + GVI = PerformHeapAllocSRoA(GV, CI, getMallocArraySize(CI, TD, true),TD); return true; } - + return false; -} +} // OptimizeOnceStoredGlobal - Try to optimize globals based on the knowledge // that only one value (besides its initializer) is ever stored to the global. @@ -1568,7 +1584,7 @@ static bool OptimizeOnceStoredGlobal(GlobalVariable *GV, Value *StoredOnceVal, GV->getInitializer()->isNullValue()) { if (Constant *SOVC = dyn_cast<Constant>(StoredOnceVal)) { if (GV->getInitializer()->getType() != SOVC->getType()) - SOVC = + SOVC = ConstantExpr::getBitCast(SOVC, GV->getInitializer()->getType()); // Optimize away any trapping uses of the loaded value. @@ -1576,7 +1592,7 @@ static bool OptimizeOnceStoredGlobal(GlobalVariable *GV, Value *StoredOnceVal, return true; } else if (CallInst *CI = extractMallocCall(StoredOnceVal)) { const Type* MallocType = getMallocAllocatedType(CI); - if (MallocType && TryToOptimizeStoreOfMallocToGlobal(GV, CI, MallocType, + if (MallocType && TryToOptimizeStoreOfMallocToGlobal(GV, CI, MallocType, GVI, TD)) return true; } @@ -1591,7 +1607,7 @@ static bool OptimizeOnceStoredGlobal(GlobalVariable *GV, Value *StoredOnceVal, /// whenever it is used. This exposes the values to other scalar optimizations. static bool TryToShrinkGlobalToBoolean(GlobalVariable *GV, Constant *OtherVal) { const Type *GVElType = GV->getType()->getElementType(); - + // If GVElType is already i1, it is already shrunk. If the type of the GV is // an FP value, pointer or vector, don't do this optimization because a select // between them is very expensive and unlikely to lead to later @@ -1611,11 +1627,11 @@ static bool TryToShrinkGlobalToBoolean(GlobalVariable *GV, Constant *OtherVal) { } DEBUG(dbgs() << " *** SHRINKING TO BOOL: " << *GV); - + // Create the new global, initializing it to false. GlobalVariable *NewGV = new GlobalVariable(Type::getInt1Ty(GV->getContext()), false, - GlobalValue::InternalLinkage, + GlobalValue::InternalLinkage, ConstantInt::getFalse(GV->getContext()), GV->getName()+".b", GV->isThreadLocal()); @@ -1684,10 +1700,12 @@ static bool TryToShrinkGlobalToBoolean(GlobalVariable *GV, Constant *OtherVal) { /// ProcessInternalGlobal - Analyze the specified global variable and optimize /// it if possible. If we make a change, return true. -bool GlobalOpt::ProcessInternalGlobal(GlobalVariable *GV, - Module::global_iterator &GVI) { - SmallPtrSet<const PHINode*, 16> PHIUsers; - GlobalStatus GS; +bool GlobalOpt::ProcessGlobal(GlobalVariable *GV, + Module::global_iterator &GVI) { + if (!GV->hasLocalLinkage()) + return false; + + // Do more involved optimizations if the global is internal. GV->removeDeadConstantUsers(); if (GV->use_empty()) { @@ -1697,140 +1715,139 @@ bool GlobalOpt::ProcessInternalGlobal(GlobalVariable *GV, return true; } - if (!AnalyzeGlobal(GV, GS, PHIUsers)) { -#if 0 - DEBUG(dbgs() << "Global: " << *GV); - DEBUG(dbgs() << " isLoaded = " << GS.isLoaded << "\n"); - DEBUG(dbgs() << " StoredType = "); - switch (GS.StoredType) { - case GlobalStatus::NotStored: DEBUG(dbgs() << "NEVER STORED\n"); break; - case GlobalStatus::isInitializerStored: DEBUG(dbgs() << "INIT STORED\n"); - break; - case GlobalStatus::isStoredOnce: DEBUG(dbgs() << "STORED ONCE\n"); break; - case GlobalStatus::isStored: DEBUG(dbgs() << "stored\n"); break; - } - if (GS.StoredType == GlobalStatus::isStoredOnce && GS.StoredOnceValue) - DEBUG(dbgs() << " StoredOnceValue = " << *GS.StoredOnceValue << "\n"); - if (GS.AccessingFunction && !GS.HasMultipleAccessingFunctions) - DEBUG(dbgs() << " AccessingFunction = " - << GS.AccessingFunction->getName() << "\n"); - DEBUG(dbgs() << " HasMultipleAccessingFunctions = " - << GS.HasMultipleAccessingFunctions << "\n"); - DEBUG(dbgs() << " HasNonInstructionUser = " - << GS.HasNonInstructionUser<<"\n"); - DEBUG(dbgs() << "\n"); -#endif - - // If this is a first class global and has only one accessing function - // and this function is main (which we know is not recursive we can make - // this global a local variable) we replace the global with a local alloca - // in this function. - // - // NOTE: It doesn't make sense to promote non single-value types since we - // are just replacing static memory to stack memory. - // - // If the global is in different address space, don't bring it to stack. - if (!GS.HasMultipleAccessingFunctions && - GS.AccessingFunction && !GS.HasNonInstructionUser && - GV->getType()->getElementType()->isSingleValueType() && - GS.AccessingFunction->getName() == "main" && - GS.AccessingFunction->hasExternalLinkage() && - GV->getType()->getAddressSpace() == 0) { - DEBUG(dbgs() << "LOCALIZING GLOBAL: " << *GV); - Instruction& FirstI = const_cast<Instruction&>(*GS.AccessingFunction - ->getEntryBlock().begin()); - const Type* ElemTy = GV->getType()->getElementType(); - // FIXME: Pass Global's alignment when globals have alignment - AllocaInst* Alloca = new AllocaInst(ElemTy, NULL, GV->getName(), &FirstI); - if (!isa<UndefValue>(GV->getInitializer())) - new StoreInst(GV->getInitializer(), Alloca, &FirstI); - - GV->replaceAllUsesWith(Alloca); + SmallPtrSet<const PHINode*, 16> PHIUsers; + GlobalStatus GS; + + if (AnalyzeGlobal(GV, GS, PHIUsers)) + return false; + + if (!GS.isCompared && !GV->hasUnnamedAddr()) { + GV->setUnnamedAddr(true); + NumUnnamed++; + } + + if (GV->isConstant() || !GV->hasInitializer()) + return false; + + return ProcessInternalGlobal(GV, GVI, PHIUsers, GS); +} + +/// ProcessInternalGlobal - Analyze the specified global variable and optimize +/// it if possible. If we make a change, return true. +bool GlobalOpt::ProcessInternalGlobal(GlobalVariable *GV, + Module::global_iterator &GVI, + const SmallPtrSet<const PHINode*, 16> &PHIUsers, + const GlobalStatus &GS) { + // If this is a first class global and has only one accessing function + // and this function is main (which we know is not recursive we can make + // this global a local variable) we replace the global with a local alloca + // in this function. + // + // NOTE: It doesn't make sense to promote non single-value types since we + // are just replacing static memory to stack memory. + // + // If the global is in different address space, don't bring it to stack. + if (!GS.HasMultipleAccessingFunctions && + GS.AccessingFunction && !GS.HasNonInstructionUser && + GV->getType()->getElementType()->isSingleValueType() && + GS.AccessingFunction->getName() == "main" && + GS.AccessingFunction->hasExternalLinkage() && + GV->getType()->getAddressSpace() == 0) { + DEBUG(dbgs() << "LOCALIZING GLOBAL: " << *GV); + Instruction& FirstI = const_cast<Instruction&>(*GS.AccessingFunction + ->getEntryBlock().begin()); + const Type* ElemTy = GV->getType()->getElementType(); + // FIXME: Pass Global's alignment when globals have alignment + AllocaInst* Alloca = new AllocaInst(ElemTy, NULL, GV->getName(), &FirstI); + if (!isa<UndefValue>(GV->getInitializer())) + new StoreInst(GV->getInitializer(), Alloca, &FirstI); + + GV->replaceAllUsesWith(Alloca); + GV->eraseFromParent(); + ++NumLocalized; + return true; + } + + // If the global is never loaded (but may be stored to), it is dead. + // Delete it now. + if (!GS.isLoaded) { + DEBUG(dbgs() << "GLOBAL NEVER LOADED: " << *GV); + + // Delete any stores we can find to the global. We may not be able to + // make it completely dead though. + bool Changed = CleanupConstantGlobalUsers(GV, GV->getInitializer()); + + // If the global is dead now, delete it. + if (GV->use_empty()) { GV->eraseFromParent(); - ++NumLocalized; - return true; + ++NumDeleted; + Changed = true; } - - // If the global is never loaded (but may be stored to), it is dead. - // Delete it now. - if (!GS.isLoaded) { - DEBUG(dbgs() << "GLOBAL NEVER LOADED: " << *GV); - - // Delete any stores we can find to the global. We may not be able to - // make it completely dead though. - bool Changed = CleanupConstantGlobalUsers(GV, GV->getInitializer()); - - // If the global is dead now, delete it. - if (GV->use_empty()) { - GV->eraseFromParent(); - ++NumDeleted; - Changed = true; - } - return Changed; + return Changed; - } else if (GS.StoredType <= GlobalStatus::isInitializerStored) { - DEBUG(dbgs() << "MARKING CONSTANT: " << *GV); - GV->setConstant(true); + } else if (GS.StoredType <= GlobalStatus::isInitializerStored) { + DEBUG(dbgs() << "MARKING CONSTANT: " << *GV); + GV->setConstant(true); - // Clean up any obviously simplifiable users now. - CleanupConstantGlobalUsers(GV, GV->getInitializer()); + // Clean up any obviously simplifiable users now. + CleanupConstantGlobalUsers(GV, GV->getInitializer()); - // If the global is dead now, just nuke it. - if (GV->use_empty()) { - DEBUG(dbgs() << " *** Marking constant allowed us to simplify " - << "all users and delete global!\n"); - GV->eraseFromParent(); - ++NumDeleted; + // If the global is dead now, just nuke it. + if (GV->use_empty()) { + DEBUG(dbgs() << " *** Marking constant allowed us to simplify " + << "all users and delete global!\n"); + GV->eraseFromParent(); + ++NumDeleted; + } + + ++NumMarked; + return true; + } else if (!GV->getInitializer()->getType()->isSingleValueType()) { + if (TargetData *TD = getAnalysisIfAvailable<TargetData>()) + if (GlobalVariable *FirstNewGV = SRAGlobal(GV, *TD)) { + GVI = FirstNewGV; // Don't skip the newly produced globals! + return true; + } + } else if (GS.StoredType == GlobalStatus::isStoredOnce) { + // If the initial value for the global was an undef value, and if only + // one other value was stored into it, we can just change the + // initializer to be the stored value, then delete all stores to the + // global. This allows us to mark it constant. + if (Constant *SOVConstant = dyn_cast<Constant>(GS.StoredOnceValue)) + if (isa<UndefValue>(GV->getInitializer())) { + // Change the initial value here. + GV->setInitializer(SOVConstant); + + // Clean up any obviously simplifiable users now. + CleanupConstantGlobalUsers(GV, GV->getInitializer()); + + if (GV->use_empty()) { + DEBUG(dbgs() << " *** Substituting initializer allowed us to " + << "simplify all users and delete global!\n"); + GV->eraseFromParent(); + ++NumDeleted; + } else { + GVI = GV; + } + ++NumSubstitute; + return true; } - ++NumMarked; + // Try to optimize globals based on the knowledge that only one value + // (besides its initializer) is ever stored to the global. + if (OptimizeOnceStoredGlobal(GV, GS.StoredOnceValue, GVI, + getAnalysisIfAvailable<TargetData>())) return true; - } else if (!GV->getInitializer()->getType()->isSingleValueType()) { - if (TargetData *TD = getAnalysisIfAvailable<TargetData>()) - if (GlobalVariable *FirstNewGV = SRAGlobal(GV, *TD)) { - GVI = FirstNewGV; // Don't skip the newly produced globals! - return true; - } - } else if (GS.StoredType == GlobalStatus::isStoredOnce) { - // If the initial value for the global was an undef value, and if only - // one other value was stored into it, we can just change the - // initializer to be the stored value, then delete all stores to the - // global. This allows us to mark it constant. - if (Constant *SOVConstant = dyn_cast<Constant>(GS.StoredOnceValue)) - if (isa<UndefValue>(GV->getInitializer())) { - // Change the initial value here. - GV->setInitializer(SOVConstant); - - // Clean up any obviously simplifiable users now. - CleanupConstantGlobalUsers(GV, GV->getInitializer()); - - if (GV->use_empty()) { - DEBUG(dbgs() << " *** Substituting initializer allowed us to " - << "simplify all users and delete global!\n"); - GV->eraseFromParent(); - ++NumDeleted; - } else { - GVI = GV; - } - ++NumSubstitute; - return true; - } - // Try to optimize globals based on the knowledge that only one value - // (besides its initializer) is ever stored to the global. - if (OptimizeOnceStoredGlobal(GV, GS.StoredOnceValue, GVI, - getAnalysisIfAvailable<TargetData>())) + // Otherwise, if the global was not a boolean, we can shrink it to be a + // boolean. + if (Constant *SOVConstant = dyn_cast<Constant>(GS.StoredOnceValue)) + if (TryToShrinkGlobalToBoolean(GV, SOVConstant)) { + ++NumShrunkToBool; return true; - - // Otherwise, if the global was not a boolean, we can shrink it to be a - // boolean. - if (Constant *SOVConstant = dyn_cast<Constant>(GS.StoredOnceValue)) - if (TryToShrinkGlobalToBoolean(GV, SOVConstant)) { - ++NumShrunkToBool; - return true; - } - } + } } + return false; } @@ -1917,10 +1934,8 @@ bool GlobalOpt::OptimizeGlobalVars(Module &M) { if (New && New != CE) GV->setInitializer(New); } - // Do more involved optimizations if the global is internal. - if (!GV->isConstant() && GV->hasLocalLinkage() && - GV->hasInitializer()) - Changed |= ProcessInternalGlobal(GV, GVI); + + Changed |= ProcessGlobal(GV, GVI); } return Changed; } @@ -1928,46 +1943,47 @@ bool GlobalOpt::OptimizeGlobalVars(Module &M) { /// FindGlobalCtors - Find the llvm.globalctors list, verifying that all /// initializers have an init priority of 65535. GlobalVariable *GlobalOpt::FindGlobalCtors(Module &M) { - for (Module::global_iterator I = M.global_begin(), E = M.global_end(); - I != E; ++I) - if (I->getName() == "llvm.global_ctors") { - // Found it, verify it's an array of { int, void()* }. - const ArrayType *ATy =dyn_cast<ArrayType>(I->getType()->getElementType()); - if (!ATy) return 0; - const StructType *STy = dyn_cast<StructType>(ATy->getElementType()); - if (!STy || STy->getNumElements() != 2 || - !STy->getElementType(0)->isIntegerTy(32)) return 0; - const PointerType *PFTy = dyn_cast<PointerType>(STy->getElementType(1)); - if (!PFTy) return 0; - const FunctionType *FTy = dyn_cast<FunctionType>(PFTy->getElementType()); - if (!FTy || !FTy->getReturnType()->isVoidTy() || - FTy->isVarArg() || FTy->getNumParams() != 0) - return 0; - - // Verify that the initializer is simple enough for us to handle. - if (!I->hasDefinitiveInitializer()) return 0; - ConstantArray *CA = dyn_cast<ConstantArray>(I->getInitializer()); - if (!CA) return 0; - for (User::op_iterator i = CA->op_begin(), e = CA->op_end(); i != e; ++i) - if (ConstantStruct *CS = dyn_cast<ConstantStruct>(*i)) { - if (isa<ConstantPointerNull>(CS->getOperand(1))) - continue; + GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors"); + if (GV == 0) return 0; + + // Found it, verify it's an array of { int, void()* }. + const ArrayType *ATy =dyn_cast<ArrayType>(GV->getType()->getElementType()); + if (!ATy) return 0; + const StructType *STy = dyn_cast<StructType>(ATy->getElementType()); + if (!STy || STy->getNumElements() != 2 || + !STy->getElementType(0)->isIntegerTy(32)) return 0; + const PointerType *PFTy = dyn_cast<PointerType>(STy->getElementType(1)); + if (!PFTy) return 0; + const FunctionType *FTy = dyn_cast<FunctionType>(PFTy->getElementType()); + if (!FTy || !FTy->getReturnType()->isVoidTy() || + FTy->isVarArg() || FTy->getNumParams() != 0) + return 0; - // Must have a function or null ptr. - if (!isa<Function>(CS->getOperand(1))) - return 0; - - // Init priority must be standard. - ConstantInt *CI = dyn_cast<ConstantInt>(CS->getOperand(0)); - if (!CI || CI->getZExtValue() != 65535) - return 0; - } else { - return 0; - } - - return I; - } - return 0; + // Verify that the initializer is simple enough for us to handle. We are + // only allowed to optimize the initializer if it is unique. + if (!GV->hasUniqueInitializer()) return 0; + + ConstantArray *CA = dyn_cast<ConstantArray>(GV->getInitializer()); + if (!CA) return 0; + + for (User::op_iterator i = CA->op_begin(), e = CA->op_end(); i != e; ++i) { + ConstantStruct *CS = dyn_cast<ConstantStruct>(*i); + if (CS == 0) return 0; + + if (isa<ConstantPointerNull>(CS->getOperand(1))) + continue; + + // Must have a function or null ptr. + if (!isa<Function>(CS->getOperand(1))) + return 0; + + // Init priority must be standard. + ConstantInt *CI = dyn_cast<ConstantInt>(CS->getOperand(0)); + if (!CI || CI->getZExtValue() != 65535) + return 0; + } + + return GV; } /// ParseGlobalCtors - Given a llvm.global_ctors list that we can understand, @@ -1985,13 +2001,13 @@ static std::vector<Function*> ParseGlobalCtors(GlobalVariable *GV) { /// InstallGlobalCtors - Given a specified llvm.global_ctors list, install the /// specified array, returning the new global to use. -static GlobalVariable *InstallGlobalCtors(GlobalVariable *GCL, +static GlobalVariable *InstallGlobalCtors(GlobalVariable *GCL, const std::vector<Function*> &Ctors) { // If we made a change, reassemble the initializer list. std::vector<Constant*> CSVals; CSVals.push_back(ConstantInt::get(Type::getInt32Ty(GCL->getContext()),65535)); CSVals.push_back(0); - + // Create the new init list. std::vector<Constant*> CAList; for (unsigned i = 0, e = Ctors.size(); i != e; ++i) { @@ -2007,26 +2023,26 @@ static GlobalVariable *InstallGlobalCtors(GlobalVariable *GCL, } CAList.push_back(ConstantStruct::get(GCL->getContext(), CSVals, false)); } - + // Create the array initializer. const Type *StructTy = cast<ArrayType>(GCL->getType()->getElementType())->getElementType(); - Constant *CA = ConstantArray::get(ArrayType::get(StructTy, + Constant *CA = ConstantArray::get(ArrayType::get(StructTy, CAList.size()), CAList); - + // If we didn't change the number of elements, don't create a new GV. if (CA->getType() == GCL->getInitializer()->getType()) { GCL->setInitializer(CA); return GCL; } - + // Create the new global and insert it next to the existing list. GlobalVariable *NGV = new GlobalVariable(CA->getType(), GCL->isConstant(), GCL->getLinkage(), CA, "", GCL->isThreadLocal()); GCL->getParent()->getGlobalList().insert(GCL, NGV); NGV->takeName(GCL); - + // Nuke the old list, replacing any uses with the new one. if (!GCL->use_empty()) { Constant *V = NGV; @@ -2035,7 +2051,7 @@ static GlobalVariable *InstallGlobalCtors(GlobalVariable *GCL, GCL->replaceAllUsesWith(V); } GCL->eraseFromParent(); - + if (Ctors.size()) return NGV; else @@ -2043,17 +2059,86 @@ static GlobalVariable *InstallGlobalCtors(GlobalVariable *GCL, } -static Constant *getVal(DenseMap<Value*, Constant*> &ComputedValues, - Value *V) { +static Constant *getVal(DenseMap<Value*, Constant*> &ComputedValues, Value *V) { if (Constant *CV = dyn_cast<Constant>(V)) return CV; Constant *R = ComputedValues[V]; assert(R && "Reference to an uncomputed value!"); return R; } +static inline bool +isSimpleEnoughValueToCommit(Constant *C, + SmallPtrSet<Constant*, 8> &SimpleConstants); + + +/// isSimpleEnoughValueToCommit - Return true if the specified constant can be +/// handled by the code generator. We don't want to generate something like: +/// void *X = &X/42; +/// because the code generator doesn't have a relocation that can handle that. +/// +/// This function should be called if C was not found (but just got inserted) +/// in SimpleConstants to avoid having to rescan the same constants all the +/// time. +static bool isSimpleEnoughValueToCommitHelper(Constant *C, + SmallPtrSet<Constant*, 8> &SimpleConstants) { + // Simple integer, undef, constant aggregate zero, global addresses, etc are + // all supported. + if (C->getNumOperands() == 0 || isa<BlockAddress>(C) || + isa<GlobalValue>(C)) + return true; + + // Aggregate values are safe if all their elements are. + if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) || + isa<ConstantVector>(C)) { + for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i) { + Constant *Op = cast<Constant>(C->getOperand(i)); + if (!isSimpleEnoughValueToCommit(Op, SimpleConstants)) + return false; + } + return true; + } + + // We don't know exactly what relocations are allowed in constant expressions, + // so we allow &global+constantoffset, which is safe and uniformly supported + // across targets. + ConstantExpr *CE = cast<ConstantExpr>(C); + switch (CE->getOpcode()) { + case Instruction::BitCast: + case Instruction::IntToPtr: + case Instruction::PtrToInt: + // These casts are always fine if the casted value is. + return isSimpleEnoughValueToCommit(CE->getOperand(0), SimpleConstants); + + // GEP is fine if it is simple + constant offset. + case Instruction::GetElementPtr: + for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i) + if (!isa<ConstantInt>(CE->getOperand(i))) + return false; + return isSimpleEnoughValueToCommit(CE->getOperand(0), SimpleConstants); + + case Instruction::Add: + // We allow simple+cst. + if (!isa<ConstantInt>(CE->getOperand(1))) + return false; + return isSimpleEnoughValueToCommit(CE->getOperand(0), SimpleConstants); + } + return false; +} + +static inline bool +isSimpleEnoughValueToCommit(Constant *C, + SmallPtrSet<Constant*, 8> &SimpleConstants) { + // If we already checked this constant, we win. + if (!SimpleConstants.insert(C)) return true; + // Check the constant. + return isSimpleEnoughValueToCommitHelper(C, SimpleConstants); +} + + /// isSimpleEnoughPointerToCommit - Return true if this constant is simple -/// enough for us to understand. In particular, if it is a cast of something, -/// we punt. We basically just support direct accesses to globals and GEP's of +/// enough for us to understand. In particular, if it is a cast to anything +/// other than from one pointer type to another pointer type, we punt. +/// We basically just support direct accesses to globals and GEP's of /// globals. This should be kept up to date with CommitValueTo. static bool isSimpleEnoughPointerToCommit(Constant *C) { // Conservatively, avoid aggregate types. This is because we don't @@ -2062,19 +2147,19 @@ static bool isSimpleEnoughPointerToCommit(Constant *C) { return false; if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) - // Do not allow weak/linkonce/dllimport/dllexport linkage or + // Do not allow weak/*_odr/linkonce/dllimport/dllexport linkage or // external globals. - return GV->hasDefinitiveInitializer(); + return GV->hasUniqueInitializer(); - if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) + if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) { // Handle a constantexpr gep. if (CE->getOpcode() == Instruction::GetElementPtr && isa<GlobalVariable>(CE->getOperand(0)) && cast<GEPOperator>(CE)->isInBounds()) { GlobalVariable *GV = cast<GlobalVariable>(CE->getOperand(0)); - // Do not allow weak/linkonce/dllimport/dllexport linkage or + // Do not allow weak/*_odr/linkonce/dllimport/dllexport linkage or // external globals. - if (!GV->hasDefinitiveInitializer()) + if (!GV->hasUniqueInitializer()) return false; // The first index must be zero. @@ -2087,7 +2172,18 @@ static bool isSimpleEnoughPointerToCommit(Constant *C) { return false; return ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE); + + // A constantexpr bitcast from a pointer to another pointer is a no-op, + // and we know how to evaluate it by moving the bitcast from the pointer + // operand to the value operand. + } else if (CE->getOpcode() == Instruction::BitCast && + isa<GlobalVariable>(CE->getOperand(0))) { + // Do not allow weak/*_odr/linkonce/dllimport/dllexport linkage or + // external globals. + return cast<GlobalVariable>(CE->getOperand(0))->hasUniqueInitializer(); } + } + return false; } @@ -2101,7 +2197,7 @@ static Constant *EvaluateStoreInto(Constant *Init, Constant *Val, assert(Val->getType() == Init->getType() && "Type mismatch!"); return Val; } - + std::vector<Constant*> Elts; if (const StructType *STy = dyn_cast<StructType>(Init->getType())) { @@ -2119,13 +2215,13 @@ static Constant *EvaluateStoreInto(Constant *Init, Constant *Val, llvm_unreachable("This code is out of sync with " " ConstantFoldLoadThroughGEPConstantExpr"); } - + // Replace the element that we are supposed to. ConstantInt *CU = cast<ConstantInt>(Addr->getOperand(OpNo)); unsigned Idx = CU->getZExtValue(); assert(Idx < STy->getNumElements() && "Struct index out of range!"); Elts[Idx] = EvaluateStoreInto(Elts[Idx], Val, Addr, OpNo+1); - + // Return the modified struct. return ConstantStruct::get(Init->getContext(), &Elts[0], Elts.size(), STy->isPacked()); @@ -2138,8 +2234,8 @@ static Constant *EvaluateStoreInto(Constant *Init, Constant *Val, NumElts = ATy->getNumElements(); else NumElts = cast<VectorType>(InitTy)->getNumElements(); - - + + // Break up the array into elements. if (ConstantArray *CA = dyn_cast<ConstantArray>(Init)) { for (User::op_iterator i = CA->op_begin(), e = CA->op_end(); i != e; ++i) @@ -2154,16 +2250,15 @@ static Constant *EvaluateStoreInto(Constant *Init, Constant *Val, " ConstantFoldLoadThroughGEPConstantExpr"); Elts.assign(NumElts, UndefValue::get(InitTy->getElementType())); } - + assert(CI->getZExtValue() < NumElts); Elts[CI->getZExtValue()] = EvaluateStoreInto(Elts[CI->getZExtValue()], Val, Addr, OpNo+1); - + if (Init->getType()->isArrayTy()) return ConstantArray::get(cast<ArrayType>(InitTy), Elts); - else - return ConstantVector::get(&Elts[0], Elts.size()); - } + return ConstantVector::get(Elts); + } } /// CommitValueTo - We have decided that Addr (which satisfies the predicate @@ -2189,14 +2284,14 @@ static Constant *ComputeLoadResult(Constant *P, // is the most up-to-date. DenseMap<Constant*, Constant*>::const_iterator I = Memory.find(P); if (I != Memory.end()) return I->second; - + // Access it. if (GlobalVariable *GV = dyn_cast<GlobalVariable>(P)) { if (GV->hasDefinitiveInitializer()) return GV->getInitializer(); return 0; } - + // Handle a constantexpr getelementptr. if (ConstantExpr *CE = dyn_cast<ConstantExpr>(P)) if (CE->getOpcode() == Instruction::GetElementPtr && @@ -2216,17 +2311,19 @@ static bool EvaluateFunction(Function *F, Constant *&RetVal, const SmallVectorImpl<Constant*> &ActualArgs, std::vector<Function*> &CallStack, DenseMap<Constant*, Constant*> &MutatedMemory, - std::vector<GlobalVariable*> &AllocaTmps) { + std::vector<GlobalVariable*> &AllocaTmps, + SmallPtrSet<Constant*, 8> &SimpleConstants, + const TargetData *TD) { // Check to see if this function is already executing (recursion). If so, // bail out. TODO: we might want to accept limited recursion. if (std::find(CallStack.begin(), CallStack.end(), F) != CallStack.end()) return false; - + CallStack.push_back(F); - + /// Values - As we compute SSA register values, we store their contents here. DenseMap<Value*, Constant*> Values; - + // Initialize arguments to the incoming values specified. unsigned ArgNo = 0; for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); AI != E; @@ -2237,21 +2334,65 @@ static bool EvaluateFunction(Function *F, Constant *&RetVal, /// we can only evaluate any one basic block at most once. This set keeps /// track of what we have executed so we can detect recursive cases etc. SmallPtrSet<BasicBlock*, 32> ExecutedBlocks; - + // CurInst - The current instruction we're evaluating. BasicBlock::iterator CurInst = F->begin()->begin(); - + // This is the main evaluation loop. while (1) { Constant *InstResult = 0; - + if (StoreInst *SI = dyn_cast<StoreInst>(CurInst)) { if (SI->isVolatile()) return false; // no volatile accesses. Constant *Ptr = getVal(Values, SI->getOperand(1)); if (!isSimpleEnoughPointerToCommit(Ptr)) // If this is too complex for us to commit, reject it. return false; + Constant *Val = getVal(Values, SI->getOperand(0)); + + // If this might be too difficult for the backend to handle (e.g. the addr + // of one global variable divided by another) then we can't commit it. + if (!isSimpleEnoughValueToCommit(Val, SimpleConstants)) + return false; + + if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr)) + if (CE->getOpcode() == Instruction::BitCast) { + // If we're evaluating a store through a bitcast, then we need + // to pull the bitcast off the pointer type and push it onto the + // stored value. + Ptr = CE->getOperand(0); + + const Type *NewTy=cast<PointerType>(Ptr->getType())->getElementType(); + + // In order to push the bitcast onto the stored value, a bitcast + // from NewTy to Val's type must be legal. If it's not, we can try + // introspecting NewTy to find a legal conversion. + while (!Val->getType()->canLosslesslyBitCastTo(NewTy)) { + // If NewTy is a struct, we can convert the pointer to the struct + // into a pointer to its first member. + // FIXME: This could be extended to support arrays as well. + if (const StructType *STy = dyn_cast<StructType>(NewTy)) { + NewTy = STy->getTypeAtIndex(0U); + + const IntegerType *IdxTy =IntegerType::get(NewTy->getContext(), 32); + Constant *IdxZero = ConstantInt::get(IdxTy, 0, false); + Constant * const IdxList[] = {IdxZero, IdxZero}; + + Ptr = ConstantExpr::getGetElementPtr(Ptr, IdxList, 2); + + // If we can't improve the situation by introspecting NewTy, + // we have to give up. + } else { + return 0; + } + } + + // If we found compatible types, go ahead and push the bitcast + // onto the stored value. + Val = ConstantExpr::getBitCast(Val, NewTy); + } + MutatedMemory[Ptr] = Val; } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(CurInst)) { InstResult = ConstantExpr::get(BO->getOpcode(), @@ -2290,7 +2431,7 @@ static bool EvaluateFunction(Function *F, Constant *&RetVal, GlobalValue::InternalLinkage, UndefValue::get(Ty), AI->getName())); - InstResult = AllocaTmps.back(); + InstResult = AllocaTmps.back(); } else if (CallInst *CI = dyn_cast<CallInst>(CurInst)) { // Debug info can safely be ignored here. @@ -2324,11 +2465,11 @@ static bool EvaluateFunction(Function *F, Constant *&RetVal, } else { if (Callee->getFunctionType()->isVarArg()) return false; - + Constant *RetVal; // Execute the call, if successful, use the return value. if (!EvaluateFunction(Callee, RetVal, Formals, CallStack, - MutatedMemory, AllocaTmps)) + MutatedMemory, AllocaTmps, SimpleConstants, TD)) return false; InstResult = RetVal; } @@ -2342,7 +2483,7 @@ static bool EvaluateFunction(Function *F, Constant *&RetVal, dyn_cast<ConstantInt>(getVal(Values, BI->getCondition())); if (!Cond) return false; // Cannot determine. - NewBB = BI->getSuccessor(!Cond->getZExtValue()); + NewBB = BI->getSuccessor(!Cond->getZExtValue()); } } else if (SwitchInst *SI = dyn_cast<SwitchInst>(CurInst)) { ConstantInt *Val = @@ -2358,20 +2499,20 @@ static bool EvaluateFunction(Function *F, Constant *&RetVal, } else if (ReturnInst *RI = dyn_cast<ReturnInst>(CurInst)) { if (RI->getNumOperands()) RetVal = getVal(Values, RI->getOperand(0)); - + CallStack.pop_back(); // return from fn. return true; // We succeeded at evaluating this ctor! } else { // invoke, unwind, unreachable. return false; // Cannot handle this terminator. } - + // Okay, we succeeded in evaluating this control flow. See if we have // executed the new block before. If so, we have a looping function, // which we cannot evaluate in reasonable time. if (!ExecutedBlocks.insert(NewBB)) return false; // looped! - + // Okay, we have never been in this block before. Check to see if there // are any PHI nodes. If so, evaluate them with information about where // we came from. @@ -2387,10 +2528,14 @@ static bool EvaluateFunction(Function *F, Constant *&RetVal, // Did not know how to evaluate this! return false; } - - if (!CurInst->use_empty()) + + if (!CurInst->use_empty()) { + if (ConstantExpr *CE = dyn_cast<ConstantExpr>(InstResult)) + InstResult = ConstantFoldConstantExpression(CE, TD); + Values[CurInst] = InstResult; - + } + // Advance program counter. ++CurInst; } @@ -2398,7 +2543,7 @@ static bool EvaluateFunction(Function *F, Constant *&RetVal, /// EvaluateStaticConstructor - Evaluate static constructors in the function, if /// we can. Return true if we can, false otherwise. -static bool EvaluateStaticConstructor(Function *F) { +static bool EvaluateStaticConstructor(Function *F, const TargetData *TD) { /// MutatedMemory - For each store we execute, we update this map. Loads /// check this to get the most up-to-date value. If evaluation is successful, /// this state is committed to the process. @@ -2408,17 +2553,23 @@ static bool EvaluateStaticConstructor(Function *F) { /// to represent its body. This vector is needed so we can delete the /// temporary globals when we are done. std::vector<GlobalVariable*> AllocaTmps; - + /// CallStack - This is used to detect recursion. In pathological situations /// we could hit exponential behavior, but at least there is nothing /// unbounded. std::vector<Function*> CallStack; + /// SimpleConstants - These are constants we have checked and know to be + /// simple enough to live in a static initializer of a global. + SmallPtrSet<Constant*, 8> SimpleConstants; + // Call the function. Constant *RetValDummy; bool EvalSuccess = EvaluateFunction(F, RetValDummy, SmallVector<Constant*, 0>(), CallStack, - MutatedMemory, AllocaTmps); + MutatedMemory, AllocaTmps, + SimpleConstants, TD); + if (EvalSuccess) { // We succeeded at evaluation: commit the result. DEBUG(dbgs() << "FULLY EVALUATED GLOBAL CTOR FUNCTION '" @@ -2428,13 +2579,13 @@ static bool EvaluateStaticConstructor(Function *F) { E = MutatedMemory.end(); I != E; ++I) CommitValueTo(I->second, I->first); } - + // At this point, we are done interpreting. If we created any 'alloca' // temporaries, release them now. while (!AllocaTmps.empty()) { GlobalVariable *Tmp = AllocaTmps.back(); AllocaTmps.pop_back(); - + // If there are still users of the alloca, the program is doing something // silly, e.g. storing the address of the alloca somewhere and using it // later. Since this is undefined, we'll just make it be null. @@ -2442,7 +2593,7 @@ static bool EvaluateStaticConstructor(Function *F) { Tmp->replaceAllUsesWith(Constant::getNullValue(Tmp->getType())); delete Tmp; } - + return EvalSuccess; } @@ -2454,7 +2605,8 @@ bool GlobalOpt::OptimizeGlobalCtorsList(GlobalVariable *&GCL) { std::vector<Function*> Ctors = ParseGlobalCtors(GCL); bool MadeChange = false; if (Ctors.empty()) return false; - + + const TargetData *TD = getAnalysisIfAvailable<TargetData>(); // Loop over global ctors, optimizing them when we can. for (unsigned i = 0; i != Ctors.size(); ++i) { Function *F = Ctors[i]; @@ -2467,12 +2619,12 @@ bool GlobalOpt::OptimizeGlobalCtorsList(GlobalVariable *&GCL) { } break; } - + // We cannot simplify external ctor functions. if (F->empty()) continue; - + // If we can evaluate the ctor at compile time, do. - if (EvaluateStaticConstructor(F)) { + if (EvaluateStaticConstructor(F, TD)) { Ctors.erase(Ctors.begin()+i); MadeChange = true; --i; @@ -2480,9 +2632,9 @@ bool GlobalOpt::OptimizeGlobalCtorsList(GlobalVariable *&GCL) { continue; } } - + if (!MadeChange) return false; - + GCL = InstallGlobalCtors(GCL, Ctors); return true; } @@ -2546,21 +2698,21 @@ bool GlobalOpt::OptimizeGlobalAliases(Module &M) { bool GlobalOpt::runOnModule(Module &M) { bool Changed = false; - + // Try to find the llvm.globalctors list. GlobalVariable *GlobalCtors = FindGlobalCtors(M); bool LocalChange = true; while (LocalChange) { LocalChange = false; - + // Delete functions that are trivially dead, ccc -> fastcc LocalChange |= OptimizeFunctions(M); - + // Optimize global_ctors list. if (GlobalCtors) LocalChange |= OptimizeGlobalCtorsList(GlobalCtors); - + // Optimize non-address-taken globals. LocalChange |= OptimizeGlobalVars(M); @@ -2568,9 +2720,9 @@ bool GlobalOpt::runOnModule(Module &M) { LocalChange |= OptimizeGlobalAliases(M); Changed |= LocalChange; } - + // TODO: Move all global ctors functions to the end of the module for code // layout. - + return Changed; } |
