It's not necessary to do rounding for alloca operations when the requested
alignment is equal to the stack alignment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40004 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
new file mode 100644
index 0000000..520af87
--- /dev/null
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -0,0 +1,1988 @@
+//===- GlobalOpt.cpp - Optimize Global Variables --------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass transforms simple global variables that never have their address
+// taken. If obviously true, it marks read/write globals as constant, deletes
+// variables only stored to, etc.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "globalopt"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/CallingConv.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Instructions.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/Module.h"
+#include "llvm/Pass.h"
+#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/StringExtras.h"
+#include <algorithm>
+#include <set>
+using namespace llvm;
+
+STATISTIC(NumMarked , "Number of globals marked constant");
+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");
+STATISTIC(NumDeleted , "Number of globals deleted");
+STATISTIC(NumFnDeleted , "Number of functions deleted");
+STATISTIC(NumGlobUses , "Number of global uses devirtualized");
+STATISTIC(NumLocalized , "Number of globals localized");
+STATISTIC(NumShrunkToBool , "Number of global vars shrunk to booleans");
+STATISTIC(NumFastCallFns , "Number of functions converted to fastcc");
+STATISTIC(NumCtorsEvaluated, "Number of static ctors evaluated");
+
+namespace {
+ struct VISIBILITY_HIDDEN GlobalOpt : public ModulePass {
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<TargetData>();
+ }
+ static char ID; // Pass identification, replacement for typeid
+ GlobalOpt() : ModulePass((intptr_t)&ID) {}
+
+ bool runOnModule(Module &M);
+
+ private:
+ GlobalVariable *FindGlobalCtors(Module &M);
+ bool OptimizeFunctions(Module &M);
+ bool OptimizeGlobalVars(Module &M);
+ bool OptimizeGlobalCtorsList(GlobalVariable *&GCL);
+ bool ProcessInternalGlobal(GlobalVariable *GV,Module::global_iterator &GVI);
+ };
+
+ char GlobalOpt::ID = 0;
+ RegisterPass<GlobalOpt> X("globalopt", "Global Variable Optimizer");
+}
+
+ModulePass *llvm::createGlobalOptimizerPass() { return new GlobalOpt(); }
+
+/// GlobalStatus - As we analyze each global, keep track of some information
+/// about it. If we find out that the address of the global is taken, none of
+/// this info will be accurate.
+struct VISIBILITY_HIDDEN GlobalStatus {
+ /// isLoaded - True if the global is ever loaded. If the global isn't ever
+ /// loaded it can be deleted.
+ bool isLoaded;
+
+ /// StoredType - Keep track of what stores to the global look like.
+ ///
+ enum StoredType {
+ /// NotStored - There is no store to this global. It can thus be marked
+ /// constant.
+ NotStored,
+
+ /// isInitializerStored - This global is stored to, but the only thing
+ /// stored is the constant it was initialized with. This is only tracked
+ /// for scalar globals.
+ isInitializerStored,
+
+ /// isStoredOnce - This global is stored to, but only its initializer and
+ /// one other value is ever stored to it. If this global isStoredOnce, we
+ /// track the value stored to it in StoredOnceValue below. This is only
+ /// tracked for scalar globals.
+ isStoredOnce,
+
+ /// isStored - This global is stored to by multiple values or something else
+ /// that we cannot track.
+ isStored
+ } StoredType;
+
+ /// StoredOnceValue - If only one value (besides the initializer constant) is
+ /// ever stored to this global, keep track of what value it is.
+ Value *StoredOnceValue;
+
+ /// AccessingFunction/HasMultipleAccessingFunctions - These start out
+ /// null/false. When the first accessing function is noticed, it is recorded.
+ /// When a second different accessing function is noticed,
+ /// HasMultipleAccessingFunctions is set to true.
+ Function *AccessingFunction;
+ bool HasMultipleAccessingFunctions;
+
+ /// HasNonInstructionUser - Set to true if this global has a user that is not
+ /// an instruction (e.g. a constant expr or GV initializer).
+ bool HasNonInstructionUser;
+
+ /// HasPHIUser - Set to true if this global has a user that is a PHI node.
+ bool HasPHIUser;
+
+ /// isNotSuitableForSRA - Keep track of whether any SRA preventing users of
+ /// the global exist. Such users include GEP instruction with variable
+ /// indexes, and non-gep/load/store users like constant expr casts.
+ bool isNotSuitableForSRA;
+
+ GlobalStatus() : isLoaded(false), StoredType(NotStored), StoredOnceValue(0),
+ AccessingFunction(0), HasMultipleAccessingFunctions(false),
+ HasNonInstructionUser(false), HasPHIUser(false),
+ isNotSuitableForSRA(false) {}
+};
+
+
+
+/// ConstantIsDead - Return true if the specified constant is (transitively)
+/// dead. The constant may be used by other constants (e.g. constant arrays and
+/// constant exprs) as long as they are dead, but it cannot be used by anything
+/// else.
+static bool ConstantIsDead(Constant *C) {
+ if (isa<GlobalValue>(C)) return false;
+
+ for (Value::use_iterator UI = C->use_begin(), E = C->use_end(); UI != E; ++UI)
+ if (Constant *CU = dyn_cast<Constant>(*UI)) {
+ if (!ConstantIsDead(CU)) return false;
+ } else
+ return false;
+ return true;
+}
+
+
+/// AnalyzeGlobal - Look at all uses of the global and fill in the GlobalStatus
+/// structure. If the global has its address taken, return true to indicate we
+/// can't do anything with it.
+///
+static bool AnalyzeGlobal(Value *V, GlobalStatus &GS,
+ std::set<PHINode*> &PHIUsers) {
+ for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI)
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(*UI)) {
+ GS.HasNonInstructionUser = true;
+
+ if (AnalyzeGlobal(CE, GS, PHIUsers)) return true;
+ if (CE->getOpcode() != Instruction::GetElementPtr)
+ GS.isNotSuitableForSRA = true;
+ else if (!GS.isNotSuitableForSRA) {
+ // 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.
+ if (CE->getNumOperands() < 3 || !CE->getOperand(1)->isNullValue())
+ GS.isNotSuitableForSRA = true;
+ else {
+ for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
+ if (!isa<ConstantInt>(CE->getOperand(i))) {
+ GS.isNotSuitableForSRA = true;
+ break;
+ }
+ }
+ }
+
+ } else if (Instruction *I = dyn_cast<Instruction>(*UI)) {
+ if (!GS.HasMultipleAccessingFunctions) {
+ Function *F = I->getParent()->getParent();
+ if (GS.AccessingFunction == 0)
+ GS.AccessingFunction = F;
+ else if (GS.AccessingFunction != F)
+ GS.HasMultipleAccessingFunctions = true;
+ }
+ if (isa<LoadInst>(I)) {
+ GS.isLoaded = true;
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
+ // Don't allow a store OF the address, only stores TO the address.
+ if (SI->getOperand(0) == V) return true;
+
+ // If this is a direct store to the global (i.e., the global is a scalar
+ // value, not an aggregate), keep more specific information about
+ // stores.
+ if (GS.StoredType != GlobalStatus::isStored)
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(SI->getOperand(1))){
+ Value *StoredVal = SI->getOperand(0);
+ if (StoredVal == GV->getInitializer()) {
+ if (GS.StoredType < GlobalStatus::isInitializerStored)
+ GS.StoredType = GlobalStatus::isInitializerStored;
+ } else if (isa<LoadInst>(StoredVal) &&
+ cast<LoadInst>(StoredVal)->getOperand(0) == GV) {
+ // G = G
+ if (GS.StoredType < GlobalStatus::isInitializerStored)
+ GS.StoredType = GlobalStatus::isInitializerStored;
+ } else if (GS.StoredType < GlobalStatus::isStoredOnce) {
+ GS.StoredType = GlobalStatus::isStoredOnce;
+ GS.StoredOnceValue = StoredVal;
+ } else if (GS.StoredType == GlobalStatus::isStoredOnce &&
+ GS.StoredOnceValue == StoredVal) {
+ // noop.
+ } else {
+ GS.StoredType = GlobalStatus::isStored;
+ }
+ } else {
+ GS.StoredType = GlobalStatus::isStored;
+ }
+ } else if (isa<GetElementPtrInst>(I)) {
+ if (AnalyzeGlobal(I, GS, PHIUsers)) return true;
+
+ // If the first two indices are constants, this can be SRA'd.
+ if (isa<GlobalVariable>(I->getOperand(0))) {
+ if (I->getNumOperands() < 3 || !isa<Constant>(I->getOperand(1)) ||
+ !cast<Constant>(I->getOperand(1))->isNullValue() ||
+ !isa<ConstantInt>(I->getOperand(2)))
+ GS.isNotSuitableForSRA = true;
+ } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(I->getOperand(0))){
+ if (CE->getOpcode() != Instruction::GetElementPtr ||
+ CE->getNumOperands() < 3 || I->getNumOperands() < 2 ||
+ !isa<Constant>(I->getOperand(0)) ||
+ !cast<Constant>(I->getOperand(0))->isNullValue())
+ GS.isNotSuitableForSRA = true;
+ } else {
+ GS.isNotSuitableForSRA = true;
+ }
+ } else if (isa<SelectInst>(I)) {
+ if (AnalyzeGlobal(I, GS, PHIUsers)) return true;
+ GS.isNotSuitableForSRA = true;
+ } else if (PHINode *PN = dyn_cast<PHINode>(I)) {
+ // PHI nodes we can check just like select or GEP instructions, but we
+ // have to be careful about infinite recursion.
+ if (PHIUsers.insert(PN).second) // Not already visited.
+ if (AnalyzeGlobal(I, GS, PHIUsers)) return true;
+ GS.isNotSuitableForSRA = true;
+ GS.HasPHIUser = true;
+ } else if (isa<CmpInst>(I)) {
+ GS.isNotSuitableForSRA = true;
+ } else if (isa<MemCpyInst>(I) || isa<MemMoveInst>(I)) {
+ if (I->getOperand(1) == V)
+ GS.StoredType = GlobalStatus::isStored;
+ if (I->getOperand(2) == V)
+ GS.isLoaded = true;
+ GS.isNotSuitableForSRA = true;
+ } else if (isa<MemSetInst>(I)) {
+ assert(I->getOperand(1) == V && "Memset only takes one pointer!");
+ GS.StoredType = GlobalStatus::isStored;
+ GS.isNotSuitableForSRA = true;
+ } else {
+ return true; // Any other non-load instruction might take address!
+ }
+ } else if (Constant *C = dyn_cast<Constant>(*UI)) {
+ GS.HasNonInstructionUser = true;
+ // We might have a dead and dangling constant hanging off of here.
+ if (!ConstantIsDead(C))
+ return true;
+ } else {
+ GS.HasNonInstructionUser = true;
+ // Otherwise must be some other user.
+ return true;
+ }
+
+ return false;
+}
+
+static Constant *getAggregateConstantElement(Constant *Agg, Constant *Idx) {
+ ConstantInt *CI = dyn_cast<ConstantInt>(Idx);
+ if (!CI) return 0;
+ unsigned IdxV = CI->getZExtValue();
+
+ if (ConstantStruct *CS = dyn_cast<ConstantStruct>(Agg)) {
+ if (IdxV < CS->getNumOperands()) return CS->getOperand(IdxV);
+ } else if (ConstantArray *CA = dyn_cast<ConstantArray>(Agg)) {
+ if (IdxV < CA->getNumOperands()) return CA->getOperand(IdxV);
+ } else if (ConstantVector *CP = dyn_cast<ConstantVector>(Agg)) {
+ if (IdxV < CP->getNumOperands()) return CP->getOperand(IdxV);
+ } else if (isa<ConstantAggregateZero>(Agg)) {
+ if (const StructType *STy = dyn_cast<StructType>(Agg->getType())) {
+ if (IdxV < STy->getNumElements())
+ return Constant::getNullValue(STy->getElementType(IdxV));
+ } else if (const SequentialType *STy =
+ dyn_cast<SequentialType>(Agg->getType())) {
+ return Constant::getNullValue(STy->getElementType());
+ }
+ } else if (isa<UndefValue>(Agg)) {
+ if (const StructType *STy = dyn_cast<StructType>(Agg->getType())) {
+ if (IdxV < STy->getNumElements())
+ return UndefValue::get(STy->getElementType(IdxV));
+ } else if (const SequentialType *STy =
+ dyn_cast<SequentialType>(Agg->getType())) {
+ return UndefValue::get(STy->getElementType());
+ }
+ }
+ return 0;
+}
+
+
+/// CleanupConstantGlobalUsers - We just marked GV constant. Loop over all
+/// users of the global, cleaning up the obvious ones. This is largely just a
+/// quick scan over the use list to clean up the easy and obvious cruft. This
+/// returns true if it made a change.
+static bool CleanupConstantGlobalUsers(Value *V, Constant *Init) {
+ bool Changed = false;
+ for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;) {
+ User *U = *UI++;
+
+ if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
+ if (Init) {
+ // Replace the load with the initializer.
+ LI->replaceAllUsesWith(Init);
+ LI->eraseFromParent();
+ Changed = true;
+ }
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
+ // Store must be unreachable or storing Init into the global.
+ SI->eraseFromParent();
+ Changed = true;
+ } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) {
+ if (CE->getOpcode() == Instruction::GetElementPtr) {
+ Constant *SubInit = 0;
+ if (Init)
+ SubInit = ConstantFoldLoadThroughGEPConstantExpr(Init, CE);
+ Changed |= CleanupConstantGlobalUsers(CE, SubInit);
+ } else if (CE->getOpcode() == Instruction::BitCast &&
+ isa<PointerType>(CE->getType())) {
+ // Pointer cast, delete any stores and memsets to the global.
+ Changed |= CleanupConstantGlobalUsers(CE, 0);
+ }
+
+ if (CE->use_empty()) {
+ CE->destroyConstant();
+ Changed = true;
+ }
+ } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(U)) {
+ Constant *SubInit = 0;
+ ConstantExpr *CE =
+ dyn_cast_or_null<ConstantExpr>(ConstantFoldInstruction(GEP));
+ if (Init && CE && CE->getOpcode() == Instruction::GetElementPtr)
+ SubInit = ConstantFoldLoadThroughGEPConstantExpr(Init, CE);
+ Changed |= CleanupConstantGlobalUsers(GEP, SubInit);
+
+ if (GEP->use_empty()) {
+ GEP->eraseFromParent();
+ Changed = true;
+ }
+ } else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(U)) { // memset/cpy/mv
+ if (MI->getRawDest() == V) {
+ MI->eraseFromParent();
+ Changed = true;
+ }
+
+ } else if (Constant *C = dyn_cast<Constant>(U)) {
+ // If we have a chain of dead constantexprs or other things dangling from
+ // us, and if they are all dead, nuke them without remorse.
+ if (ConstantIsDead(C)) {
+ C->destroyConstant();
+ // This could have invalidated UI, start over from scratch.
+ CleanupConstantGlobalUsers(V, Init);
+ return true;
+ }
+ }
+ }
+ return Changed;
+}
+
+/// SRAGlobal - Perform scalar replacement of aggregates on the specified global
+/// variable. This opens the door for other optimizations by exposing the
+/// behavior of the program in a more fine-grained way. We have determined that
+/// this transformation is safe already. We return the first global variable we
+/// insert so that the caller can reprocess it.
+static GlobalVariable *SRAGlobal(GlobalVariable *GV) {
+ assert(GV->hasInternalLinkage() && !GV->isConstant());
+ Constant *Init = GV->getInitializer();
+ const Type *Ty = Init->getType();
+
+ std::vector<GlobalVariable*> NewGlobals;
+ Module::GlobalListType &Globals = GV->getParent()->getGlobalList();
+
+ if (const StructType *STy = dyn_cast<StructType>(Ty)) {
+ NewGlobals.reserve(STy->getNumElements());
+ for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
+ Constant *In = getAggregateConstantElement(Init,
+ ConstantInt::get(Type::Int32Ty, i));
+ assert(In && "Couldn't get element of initializer?");
+ GlobalVariable *NGV = new GlobalVariable(STy->getElementType(i), false,
+ GlobalVariable::InternalLinkage,
+ In, GV->getName()+"."+utostr(i),
+ (Module *)NULL,
+ GV->isThreadLocal());
+ Globals.insert(GV, NGV);
+ NewGlobals.push_back(NGV);
+ }
+ } else if (const SequentialType *STy = dyn_cast<SequentialType>(Ty)) {
+ unsigned NumElements = 0;
+ if (const ArrayType *ATy = dyn_cast<ArrayType>(STy))
+ NumElements = ATy->getNumElements();
+ else if (const VectorType *PTy = dyn_cast<VectorType>(STy))
+ NumElements = PTy->getNumElements();
+ else
+ assert(0 && "Unknown aggregate sequential type!");
+
+ if (NumElements > 16 && GV->hasNUsesOrMore(16))
+ return 0; // It's not worth it.
+ NewGlobals.reserve(NumElements);
+ for (unsigned i = 0, e = NumElements; i != e; ++i) {
+ Constant *In = getAggregateConstantElement(Init,
+ ConstantInt::get(Type::Int32Ty, i));
+ assert(In && "Couldn't get element of initializer?");
+
+ GlobalVariable *NGV = new GlobalVariable(STy->getElementType(), false,
+ GlobalVariable::InternalLinkage,
+ In, GV->getName()+"."+utostr(i),
+ (Module *)NULL,
+ GV->isThreadLocal());
+ Globals.insert(GV, NGV);
+ NewGlobals.push_back(NGV);
+ }
+ }
+
+ if (NewGlobals.empty())
+ return 0;
+
+ DOUT << "PERFORMING GLOBAL SRA ON: " << *GV;
+
+ Constant *NullInt = Constant::getNullValue(Type::Int32Ty);
+
+ // Loop over all of the uses of the global, replacing the constantexpr geps,
+ // with smaller constantexpr geps or direct references.
+ while (!GV->use_empty()) {
+ User *GEP = GV->use_back();
+ assert(((isa<ConstantExpr>(GEP) &&
+ cast<ConstantExpr>(GEP)->getOpcode()==Instruction::GetElementPtr)||
+ isa<GetElementPtrInst>(GEP)) && "NonGEP CE's are not SRAable!");
+
+ // Ignore the 1th operand, which has to be zero or else the program is quite
+ // broken (undefined). Get the 2nd operand, which is the structure or array
+ // index.
+ unsigned Val = cast<ConstantInt>(GEP->getOperand(2))->getZExtValue();
+ if (Val >= NewGlobals.size()) Val = 0; // Out of bound array access.
+
+ Value *NewPtr = NewGlobals[Val];
+
+ // Form a shorter GEP if needed.
+ if (GEP->getNumOperands() > 3)
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(GEP)) {
+ SmallVector<Constant*, 8> Idxs;
+ Idxs.push_back(NullInt);
+ for (unsigned i = 3, e = CE->getNumOperands(); i != e; ++i)
+ Idxs.push_back(CE->getOperand(i));
+ NewPtr = ConstantExpr::getGetElementPtr(cast<Constant>(NewPtr),
+ &Idxs[0], Idxs.size());
+ } else {
+ GetElementPtrInst *GEPI = cast<GetElementPtrInst>(GEP);
+ SmallVector<Value*, 8> Idxs;
+ Idxs.push_back(NullInt);
+ for (unsigned i = 3, e = GEPI->getNumOperands(); i != e; ++i)
+ Idxs.push_back(GEPI->getOperand(i));
+ NewPtr = new GetElementPtrInst(NewPtr, &Idxs[0], Idxs.size(),
+ GEPI->getName()+"."+utostr(Val), GEPI);
+ }
+ GEP->replaceAllUsesWith(NewPtr);
+
+ if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(GEP))
+ GEPI->eraseFromParent();
+ else
+ cast<ConstantExpr>(GEP)->destroyConstant();
+ }
+
+ // Delete the old global, now that it is dead.
+ Globals.erase(GV);
+ ++NumSRA;
+
+ // Loop over the new globals array deleting any globals that are obviously
+ // dead. This can arise due to scalarization of a structure or an array that
+ // has elements that are dead.
+ unsigned FirstGlobal = 0;
+ for (unsigned i = 0, e = NewGlobals.size(); i != e; ++i)
+ if (NewGlobals[i]->use_empty()) {
+ Globals.erase(NewGlobals[i]);
+ if (FirstGlobal == i) ++FirstGlobal;
+ }
+
+ return FirstGlobal != NewGlobals.size() ? NewGlobals[FirstGlobal] : 0;
+}
+
+/// AllUsesOfValueWillTrapIfNull - Return true if all users of the specified
+/// value will trap if the value is dynamically null.
+static bool AllUsesOfValueWillTrapIfNull(Value *V) {
+ for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI)
+ if (isa<LoadInst>(*UI)) {
+ // Will trap.
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
+ if (SI->getOperand(0) == V) {
+ //cerr << "NONTRAPPING USE: " << **UI;
+ return false; // Storing the value.
+ }
+ } else if (CallInst *CI = dyn_cast<CallInst>(*UI)) {
+ if (CI->getOperand(0) != V) {
+ //cerr << "NONTRAPPING USE: " << **UI;
+ return false; // Not calling the ptr
+ }
+ } else if (InvokeInst *II = dyn_cast<InvokeInst>(*UI)) {
+ if (II->getOperand(0) != V) {
+ //cerr << "NONTRAPPING USE: " << **UI;
+ return false; // Not calling the ptr
+ }
+ } else if (CastInst *CI = dyn_cast<CastInst>(*UI)) {
+ if (!AllUsesOfValueWillTrapIfNull(CI)) return false;
+ } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(*UI)) {
+ if (!AllUsesOfValueWillTrapIfNull(GEPI)) return false;
+ } else if (isa<ICmpInst>(*UI) &&
+ isa<ConstantPointerNull>(UI->getOperand(1))) {
+ // Ignore setcc X, null
+ } else {
+ //cerr << "NONTRAPPING USE: " << **UI;
+ return false;
+ }
+ return true;
+}
+
+/// AllUsesOfLoadedValueWillTrapIfNull - Return true if all uses of any loads
+/// from GV will trap if the loaded value is null. Note that this also permits
+/// comparisons of the loaded value against null, as a special case.
+static bool AllUsesOfLoadedValueWillTrapIfNull(GlobalVariable *GV) {
+ for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end(); UI!=E; ++UI)
+ if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
+ if (!AllUsesOfValueWillTrapIfNull(LI))
+ return false;
+ } else if (isa<StoreInst>(*UI)) {
+ // Ignore stores to the global.
+ } else {
+ // We don't know or understand this user, bail out.
+ //cerr << "UNKNOWN USER OF GLOBAL!: " << **UI;
+ return false;
+ }
+
+ return true;
+}
+
+static bool OptimizeAwayTrappingUsesOfValue(Value *V, Constant *NewV) {
+ bool Changed = false;
+ for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ) {
+ Instruction *I = cast<Instruction>(*UI++);
+ if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
+ LI->setOperand(0, NewV);
+ Changed = true;
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
+ if (SI->getOperand(1) == V) {
+ SI->setOperand(1, NewV);
+ Changed = true;
+ }
+ } else if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
+ if (I->getOperand(0) == V) {
+ // Calling through the pointer! Turn into a direct call, but be careful
+ // that the pointer is not also being passed as an argument.
+ I->setOperand(0, NewV);
+ Changed = true;
+ bool PassedAsArg = false;
+ for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i)
+ if (I->getOperand(i) == V) {
+ PassedAsArg = true;
+ I->setOperand(i, NewV);
+ }
+
+ if (PassedAsArg) {
+ // Being passed as an argument also. Be careful to not invalidate UI!
+ UI = V->use_begin();
+ }
+ }
+ } else if (CastInst *CI = dyn_cast<CastInst>(I)) {
+ Changed |= OptimizeAwayTrappingUsesOfValue(CI,
+ ConstantExpr::getCast(CI->getOpcode(),
+ NewV, CI->getType()));
+ if (CI->use_empty()) {
+ Changed = true;
+ CI->eraseFromParent();
+ }
+ } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
+ // Should handle GEP here.
+ SmallVector<Constant*, 8> Idxs;
+ Idxs.reserve(GEPI->getNumOperands()-1);
+ for (unsigned i = 1, e = GEPI->getNumOperands(); i != e; ++i)
+ if (Constant *C = dyn_cast<Constant>(GEPI->getOperand(i)))
+ Idxs.push_back(C);
+ else
+ break;
+ if (Idxs.size() == GEPI->getNumOperands()-1)
+ Changed |= OptimizeAwayTrappingUsesOfValue(GEPI,
+ ConstantExpr::getGetElementPtr(NewV, &Idxs[0],
+ Idxs.size()));
+ if (GEPI->use_empty()) {
+ Changed = true;
+ GEPI->eraseFromParent();
+ }
+ }
+ }
+
+ return Changed;
+}
+
+
+/// OptimizeAwayTrappingUsesOfLoads - The specified global has only one non-null
+/// value stored into it. If there are uses of the loaded value that would trap
+/// if the loaded value is dynamically null, then we know that they cannot be
+/// reachable with a null optimize away the load.
+static bool OptimizeAwayTrappingUsesOfLoads(GlobalVariable *GV, Constant *LV) {
+ std::vector<LoadInst*> Loads;
+ bool Changed = false;
+
+ // 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; ++GUI)
+ if (LoadInst *LI = dyn_cast<LoadInst>(*GUI)) {
+ Loads.push_back(LI);
+ Changed |= OptimizeAwayTrappingUsesOfValue(LI, LV);
+ } else {
+ // If we get here we could have stores, selects, or phi nodes whose values
+ // are loaded.
+ assert((isa<StoreInst>(*GUI) || isa<PHINode>(*GUI) ||
+ isa<SelectInst>(*GUI)) &&
+ "Only expect load and stores!");
+ }
+
+ if (Changed) {
+ DOUT << "OPTIMIZED LOADS FROM STORED ONCE POINTER: " << *GV;
+ ++NumGlobUses;
+ }
+
+ // Delete all of the loads we can, keeping track of whether we nuked them all!
+ bool AllLoadsGone = true;
+ while (!Loads.empty()) {
+ LoadInst *L = Loads.back();
+ if (L->use_empty()) {
+ L->eraseFromParent();
+ Changed = true;
+ } else {
+ AllLoadsGone = false;
+ }
+ Loads.pop_back();
+ }
+
+ // If we nuked all of the loads, then none of the stores are needed either,
+ // nor is the global.
+ if (AllLoadsGone) {
+ DOUT << " *** GLOBAL NOW DEAD!\n";
+ CleanupConstantGlobalUsers(GV, 0);
+ if (GV->use_empty()) {
+ GV->eraseFromParent();
+ ++NumDeleted;
+ }
+ Changed = true;
+ }
+ return Changed;
+}
+
+/// ConstantPropUsersOf - Walk the use list of V, constant folding all of the
+/// instructions that are foldable.
+static void ConstantPropUsersOf(Value *V) {
+ for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; )
+ if (Instruction *I = dyn_cast<Instruction>(*UI++))
+ if (Constant *NewC = ConstantFoldInstruction(I)) {
+ I->replaceAllUsesWith(NewC);
+
+ // Advance UI to the next non-I use to avoid invalidating it!
+ // Instructions could multiply use V.
+ while (UI != E && *UI == I)
+ ++UI;
+ I->eraseFromParent();
+ }
+}
+
+/// OptimizeGlobalAddressOfMalloc - This function takes the specified global
+/// variable, and transforms the program as if it always contained the result of
+/// the specified malloc. Because it is always the result of the specified
+/// malloc, there is no reason to actually DO the malloc. Instead, turn the
+/// malloc into a global, and any loads of GV as uses of the new global.
+static GlobalVariable *OptimizeGlobalAddressOfMalloc(GlobalVariable *GV,
+ MallocInst *MI) {
+ DOUT << "PROMOTING MALLOC GLOBAL: " << *GV << " MALLOC = " << *MI;
+ ConstantInt *NElements = cast<ConstantInt>(MI->getArraySize());
+
+ if (NElements->getZExtValue() != 1) {
+ // If we have an array allocation, transform it to a single element
+ // allocation to make the code below simpler.
+ Type *NewTy = ArrayType::get(MI->getAllocatedType(),
+ NElements->getZExtValue());
+ MallocInst *NewMI =
+ new MallocInst(NewTy, Constant::getNullValue(Type::Int32Ty),
+ MI->getAlignment(), MI->getName(), MI);
+ Value* Indices[2];
+ Indices[0] = Indices[1] = Constant::getNullValue(Type::Int32Ty);
+ Value *NewGEP = new GetElementPtrInst(NewMI, Indices, 2,
+ NewMI->getName()+".el0", MI);
+ MI->replaceAllUsesWith(NewGEP);
+ MI->eraseFromParent();
+ MI = NewMI;
+ }
+
+ // Create the new global variable. The contents of the malloc'd memory is
+ // undefined, so initialize with an undef value.
+ Constant *Init = UndefValue::get(MI->getAllocatedType());
+ GlobalVariable *NewGV = new GlobalVariable(MI->getAllocatedType(), false,
+ GlobalValue::InternalLinkage, Init,
+ GV->getName()+".body",
+ (Module *)NULL,
+ GV->isThreadLocal());
+ GV->getParent()->getGlobalList().insert(GV, NewGV);
+
+ // Anything that used the malloc now uses the global directly.
+ MI->replaceAllUsesWith(NewGV);
+
+ Constant *RepValue = NewGV;
+ if (NewGV->getType() != GV->getType()->getElementType())
+ RepValue = ConstantExpr::getBitCast(RepValue,
+ GV->getType()->getElementType());
+
+ // If there is a comparison against null, we will insert a global bool to
+ // keep track of whether the global was initialized yet or not.
+ GlobalVariable *InitBool =
+ new GlobalVariable(Type::Int1Ty, false, GlobalValue::InternalLinkage,
+ ConstantInt::getFalse(), GV->getName()+".init",
+ (Module *)NULL, GV->isThreadLocal());
+ bool InitBoolUsed = false;
+
+ // Loop over all uses of GV, processing them in turn.
+ std::vector<StoreInst*> Stores;
+ while (!GV->use_empty())
+ if (LoadInst *LI = dyn_cast<LoadInst>(GV->use_back())) {
+ while (!LI->use_empty()) {
+ Use &LoadUse = LI->use_begin().getUse();
+ if (!isa<ICmpInst>(LoadUse.getUser()))
+ LoadUse = RepValue;
+ else {
+ ICmpInst *CI = cast<ICmpInst>(LoadUse.getUser());
+ // Replace the cmp X, 0 with a use of the bool value.
+ Value *LV = new LoadInst(InitBool, InitBool->getName()+".val", CI);
+ InitBoolUsed = true;
+ switch (CI->getPredicate()) {
+ default: assert(0 && "Unknown ICmp Predicate!");
+ case ICmpInst::ICMP_ULT:
+ case ICmpInst::ICMP_SLT:
+ LV = ConstantInt::getFalse(); // X < null -> always false
+ break;
+ case ICmpInst::ICMP_ULE:
+ case ICmpInst::ICMP_SLE:
+ case ICmpInst::ICMP_EQ:
+ LV = BinaryOperator::createNot(LV, "notinit", CI);
+ break;
+ case ICmpInst::ICMP_NE:
+ case ICmpInst::ICMP_UGE:
+ case ICmpInst::ICMP_SGE:
+ case ICmpInst::ICMP_UGT:
+ case ICmpInst::ICMP_SGT:
+ break; // no change.
+ }
+ CI->replaceAllUsesWith(LV);
+ CI->eraseFromParent();
+ }
+ }
+ LI->eraseFromParent();
+ } else {
+ StoreInst *SI = cast<StoreInst>(GV->use_back());
+ // The global is initialized when the store to it occurs.
+ new StoreInst(ConstantInt::getTrue(), InitBool, SI);
+ SI->eraseFromParent();
+ }
+
+ // If the initialization boolean was used, insert it, otherwise delete it.
+ if (!InitBoolUsed) {
+ while (!InitBool->use_empty()) // Delete initializations
+ cast<Instruction>(InitBool->use_back())->eraseFromParent();
+ delete InitBool;
+ } else
+ GV->getParent()->getGlobalList().insert(GV, InitBool);
+
+
+ // Now the GV is dead, nuke it and the malloc.
+ GV->eraseFromParent();
+ MI->eraseFromParent();
+
+ // To further other optimizations, loop over all users of NewGV and try to
+ // constant prop them. This will promote GEP instructions with constant
+ // indices into GEP constant-exprs, which will allow global-opt to hack on it.
+ ConstantPropUsersOf(NewGV);
+ if (RepValue != NewGV)
+ ConstantPropUsersOf(RepValue);
+
+ return NewGV;
+}
+
+/// ValueIsOnlyUsedLocallyOrStoredToOneGlobal - Scan the use-list of V checking
+/// to make sure that there are no complex uses of V. We permit simple things
+/// like dereferencing the pointer, but not storing through the address, unless
+/// it is to the specified global.
+static bool ValueIsOnlyUsedLocallyOrStoredToOneGlobal(Instruction *V,
+ GlobalVariable *GV) {
+ for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI)
+ if (isa<LoadInst>(*UI) || isa<CmpInst>(*UI)) {
+ // Fine, ignore.
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
+ if (SI->getOperand(0) == V && SI->getOperand(1) != GV)
+ return false; // Storing the pointer itself... bad.
+ // Otherwise, storing through it, or storing into GV... fine.
+ } else if (isa<GetElementPtrInst>(*UI) || isa<SelectInst>(*UI)) {
+ if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(cast<Instruction>(*UI),GV))
+ return false;
+ } else {
+ return false;
+ }
+ return true;
+}
+
+/// 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
+/// 'ValueIsOnlyUsedLocallyOrStoredToOneGlobal' predicate.
+static void ReplaceUsesOfMallocWithGlobal(Instruction *Alloc,
+ GlobalVariable *GV) {
+ while (!Alloc->use_empty()) {
+ Instruction *U = Alloc->use_back();
+ if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
+ // If this is the store of the allocation into the global, remove it.
+ if (SI->getOperand(1) == GV) {
+ SI->eraseFromParent();
+ continue;
+ }
+ }
+
+ // Insert a load from the global, and use it instead of the malloc.
+ Value *NL = new LoadInst(GV, GV->getName()+".val", U);
+ U->replaceUsesOfWith(Alloc, NL);
+ }
+}
+
+/// GlobalLoadUsesSimpleEnoughForHeapSRA - If all users of values loaded from
+/// GV are simple enough to perform HeapSRA, return true.
+static bool GlobalLoadUsesSimpleEnoughForHeapSRA(GlobalVariable *GV) {
+ for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end(); UI != E;
+ ++UI)
+ if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
+ // We permit two users of the load: setcc comparing against the null
+ // pointer, and a getelementptr of a specific form.
+ for (Value::use_iterator UI = LI->use_begin(), E = LI->use_end(); UI != E;
+ ++UI) {
+ // Comparison against null is ok.
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(*UI)) {
+ if (!isa<ConstantPointerNull>(ICI->getOperand(1)))
+ return false;
+ continue;
+ }
+
+ // getelementptr is also ok, but only a simple form.
+ GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(*UI);
+ if (!GEPI) return false;
+
+ // Must index into the array and into the struct.
+ if (GEPI->getNumOperands() < 3)
+ return false;
+
+ // Otherwise the GEP is ok.
+ continue;
+ }
+ }
+ return true;
+}
+
+/// RewriteUsesOfLoadForHeapSRoA - We are performing Heap SRoA on a global. Ptr
+/// is a value loaded from the global. Eliminate all uses of Ptr, making them
+/// use FieldGlobals instead. All uses of loaded values satisfy
+/// GlobalLoadUsesSimpleEnoughForHeapSRA.
+static void RewriteUsesOfLoadForHeapSRoA(LoadInst *Ptr,
+ const std::vector<GlobalVariable*> &FieldGlobals) {
+ std::vector<Value *> InsertedLoadsForPtr;
+ //InsertedLoadsForPtr.resize(FieldGlobals.size());
+ while (!Ptr->use_empty()) {
+ Instruction *User = Ptr->use_back();
+
+ // If this is a comparison against null, handle it.
+ if (ICmpInst *SCI = dyn_cast<ICmpInst>(User)) {
+ assert(isa<ConstantPointerNull>(SCI->getOperand(1)));
+ // If we have a setcc of the loaded pointer, we can use a setcc of any
+ // field.
+ Value *NPtr;
+ if (InsertedLoadsForPtr.empty()) {
+ NPtr = new LoadInst(FieldGlobals[0], Ptr->getName()+".f0", Ptr);
+ InsertedLoadsForPtr.push_back(Ptr);
+ } else {
+ NPtr = InsertedLoadsForPtr.back();
+ }
+
+ Value *New = new ICmpInst(SCI->getPredicate(), NPtr,
+ Constant::getNullValue(NPtr->getType()),
+ SCI->getName(), SCI);
+ SCI->replaceAllUsesWith(New);
+ SCI->eraseFromParent();
+ continue;
+ }
+
+ // Otherwise, this should be: 'getelementptr Ptr, Idx, uint FieldNo ...'
+ GetElementPtrInst *GEPI = cast<GetElementPtrInst>(User);
+ 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();
+ if (InsertedLoadsForPtr.size() <= FieldNo)
+ InsertedLoadsForPtr.resize(FieldNo+1);
+ if (InsertedLoadsForPtr[FieldNo] == 0)
+ InsertedLoadsForPtr[FieldNo] = new LoadInst(FieldGlobals[FieldNo],
+ Ptr->getName()+".f" +
+ utostr(FieldNo), Ptr);
+ Value *NewPtr = InsertedLoadsForPtr[FieldNo];
+
+ // 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 = new GetElementPtrInst(NewPtr, &GEPIdx[0], GEPIdx.size(),
+ GEPI->getName(), GEPI);
+ GEPI->replaceAllUsesWith(NGEPI);
+ GEPI->eraseFromParent();
+ }
+}
+
+/// PerformHeapAllocSRoA - MI is an allocation of an array of structures. Break
+/// it up into multiple allocations of arrays of the fields.
+static GlobalVariable *PerformHeapAllocSRoA(GlobalVariable *GV, MallocInst *MI){
+ DOUT << "SROA HEAP ALLOC: " << *GV << " MALLOC = " << *MI;
+ const StructType *STy = cast<StructType>(MI->getAllocatedType());
+
+ // There is guaranteed to be at least one use of the malloc (storing
+ // it into GV). If there are other uses, change them to be uses of
+ // the global to simplify later code. This also deletes the store
+ // into GV.
+ ReplaceUsesOfMallocWithGlobal(MI, GV);
+
+ // Okay, at this point, there are no users of the malloc. Insert N
+ // new mallocs at the same place as MI, and N globals.
+ std::vector<GlobalVariable*> FieldGlobals;
+ std::vector<MallocInst*> FieldMallocs;
+
+ for (unsigned FieldNo = 0, e = STy->getNumElements(); FieldNo != e;++FieldNo){
+ const Type *FieldTy = STy->getElementType(FieldNo);
+ const Type *PFieldTy = PointerType::get(FieldTy);
+
+ GlobalVariable *NGV =
+ new GlobalVariable(PFieldTy, false, GlobalValue::InternalLinkage,
+ Constant::getNullValue(PFieldTy),
+ GV->getName() + ".f" + utostr(FieldNo), GV,
+ GV->isThreadLocal());
+ FieldGlobals.push_back(NGV);
+
+ MallocInst *NMI = new MallocInst(FieldTy, MI->getArraySize(),
+ MI->getName() + ".f" + utostr(FieldNo),MI);
+ FieldMallocs.push_back(NMI);
+ new StoreInst(NMI, NGV, MI);
+ }
+
+ // 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
+ // could fail. As such, we emit code that looks like this:
+ // F0 = malloc(field0)
+ // F1 = malloc(field1)
+ // F2 = malloc(field2)
+ // if (F0 == 0 || F1 == 0 || F2 == 0) {
+ // if (F0) { free(F0); F0 = 0; }
+ // if (F1) { free(F1); F1 = 0; }
+ // if (F2) { free(F2); F2 = 0; }
+ // }
+ Value *RunningOr = 0;
+ for (unsigned i = 0, e = FieldMallocs.size(); i != e; ++i) {
+ Value *Cond = new ICmpInst(ICmpInst::ICMP_EQ, FieldMallocs[i],
+ Constant::getNullValue(FieldMallocs[i]->getType()),
+ "isnull", MI);
+ if (!RunningOr)
+ RunningOr = Cond; // First seteq
+ else
+ RunningOr = BinaryOperator::createOr(RunningOr, Cond, "tmp", MI);
+ }
+
+ // Split the basic block at the old malloc.
+ BasicBlock *OrigBB = MI->getParent();
+ BasicBlock *ContBB = OrigBB->splitBasicBlock(MI, "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 = new BasicBlock("malloc_ret_null",
+ OrigBB->getParent());
+
+ // Remove the uncond branch from OrigBB to ContBB, turning it into a cond
+ // branch on RunningOr.
+ OrigBB->getTerminator()->eraseFromParent();
+ new BranchInst(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(ICmpInst::ICMP_NE, GVVal,
+ Constant::getNullValue(GVVal->getType()),
+ "tmp", NullPtrBlock);
+ BasicBlock *FreeBlock = new BasicBlock("free_it", OrigBB->getParent());
+ BasicBlock *NextBlock = new BasicBlock("next", OrigBB->getParent());
+ new BranchInst(FreeBlock, NextBlock, Cmp, NullPtrBlock);
+
+ // Fill in FreeBlock.
+ new FreeInst(GVVal, FreeBlock);
+ new StoreInst(Constant::getNullValue(GVVal->getType()), FieldGlobals[i],
+ FreeBlock);
+ new BranchInst(NextBlock, FreeBlock);
+
+ NullPtrBlock = NextBlock;
+ }
+
+ new BranchInst(ContBB, NullPtrBlock);
+
+
+ // MI is no longer needed, remove it.
+ MI->eraseFromParent();
+
+
+ // 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.
+ while (!GV->use_empty()) {
+ if (LoadInst *LI = dyn_cast<LoadInst>(GV->use_back())) {
+ RewriteUsesOfLoadForHeapSRoA(LI, FieldGlobals);
+ LI->eraseFromParent();
+ } else {
+ // Must be a store of null.
+ StoreInst *SI = cast<StoreInst>(GV->use_back());
+ assert(isa<Constant>(SI->getOperand(0)) &&
+ cast<Constant>(SI->getOperand(0))->isNullValue() &&
+ "Unexpected heap-sra user!");
+
+ // Insert a store of null into each global.
+ for (unsigned i = 0, e = FieldGlobals.size(); i != e; ++i) {
+ Constant *Null =
+ Constant::getNullValue(FieldGlobals[i]->getType()->getElementType());
+ new StoreInst(Null, FieldGlobals[i], SI);
+ }
+ // Erase the original store.
+ SI->eraseFromParent();
+ }
+ }
+
+ // The old global is now dead, remove it.
+ GV->eraseFromParent();
+
+ ++NumHeapSRA;
+ return FieldGlobals[0];
+}
+
+
+// OptimizeOnceStoredGlobal - Try to optimize globals based on the knowledge
+// that only one value (besides its initializer) is ever stored to the global.
+static bool OptimizeOnceStoredGlobal(GlobalVariable *GV, Value *StoredOnceVal,
+ Module::global_iterator &GVI,
+ TargetData &TD) {
+ if (CastInst *CI = dyn_cast<CastInst>(StoredOnceVal))
+ StoredOnceVal = CI->getOperand(0);
+ else if (GetElementPtrInst *GEPI =dyn_cast<GetElementPtrInst>(StoredOnceVal)){
+ // "getelementptr Ptr, 0, 0, 0" is really just a cast.
+ bool IsJustACast = true;
+ for (unsigned i = 1, e = GEPI->getNumOperands(); i != e; ++i)
+ if (!isa<Constant>(GEPI->getOperand(i)) ||
+ !cast<Constant>(GEPI->getOperand(i))->isNullValue()) {
+ IsJustACast = false;
+ break;
+ }
+ if (IsJustACast)
+ StoredOnceVal = GEPI->getOperand(0);
+ }
+
+ // If we are dealing with a pointer global that is initialized to null and
+ // only has one (non-null) value stored into it, then we can optimize any
+ // users of the loaded value (often calls and loads) that would trap if the
+ // value was null.
+ if (isa<PointerType>(GV->getInitializer()->getType()) &&
+ GV->getInitializer()->isNullValue()) {
+ if (Constant *SOVC = dyn_cast<Constant>(StoredOnceVal)) {
+ if (GV->getInitializer()->getType() != SOVC->getType())
+ SOVC = ConstantExpr::getBitCast(SOVC, GV->getInitializer()->getType());
+
+ // Optimize away any trapping uses of the loaded value.
+ if (OptimizeAwayTrappingUsesOfLoads(GV, SOVC))
+ return true;
+ } else if (MallocInst *MI = dyn_cast<MallocInst>(StoredOnceVal)) {
+ // If this is a malloc of an abstract type, don't touch it.
+ if (!MI->getAllocatedType()->isSized())
+ return false;
+
+ // We can't optimize this global unless all uses of it are *known* to be
+ // of the malloc value, not of the null initializer value (consider a use
+ // that compares the global's value against zero to see if the malloc has
+ // been reached). To do this, we check to see if all uses of the global
+ // would trap if the global were null: this proves that they must all
+ // happen after the malloc.
+ if (!AllUsesOfLoadedValueWillTrapIfNull(GV))
+ return false;
+
+ // We can't optimize this if the malloc itself is used in a complex way,
+ // for example, being stored into multiple globals. This allows the
+ // malloc to be stored into the specified global, loaded setcc'd, and
+ // GEP'd. These are all things we could transform to using the global
+ // for.
+ if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(MI, GV))
+ return false;
+
+
+ // If we have a global that is only initialized with a fixed size malloc,
+ // transform the program to use global memory instead of malloc'd memory.
+ // This eliminates dynamic allocation, avoids an indirection accessing the
+ // data, and exposes the resultant global to further GlobalOpt.
+ if (ConstantInt *NElements = dyn_cast<ConstantInt>(MI->getArraySize())) {
+ // Restrict this transformation to only working on small allocations
+ // (2048 bytes currently), as we don't want to introduce a 16M global or
+ // something.
+ if (NElements->getZExtValue()*
+ TD.getTypeSize(MI->getAllocatedType()) < 2048) {
+ GVI = OptimizeGlobalAddressOfMalloc(GV, MI);
+ 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.
+ if (const StructType *AllocTy =
+ dyn_cast<StructType>(MI->getAllocatedType())) {
+ // This the structure has an unreasonable number of fields, leave it
+ // alone.
+ if (AllocTy->getNumElements() <= 16 && AllocTy->getNumElements() > 0 &&
+ GlobalLoadUsesSimpleEnoughForHeapSRA(GV)) {
+ GVI = PerformHeapAllocSRoA(GV, MI);
+ return true;
+ }
+ }
+ }
+ }
+
+ return false;
+}
+
+/// ShrinkGlobalToBoolean - At this point, we have learned that the only two
+/// values ever stored into GV are its initializer and OtherVal.
+static void ShrinkGlobalToBoolean(GlobalVariable *GV, Constant *OtherVal) {
+ // Create the new global, initializing it to false.
+ GlobalVariable *NewGV = new GlobalVariable(Type::Int1Ty, false,
+ GlobalValue::InternalLinkage, ConstantInt::getFalse(),
+ GV->getName()+".b",
+ (Module *)NULL,
+ GV->isThreadLocal());
+ GV->getParent()->getGlobalList().insert(GV, NewGV);
+
+ Constant *InitVal = GV->getInitializer();
+ assert(InitVal->getType() != Type::Int1Ty && "No reason to shrink to bool!");
+
+ // If initialized to zero and storing one into the global, we can use a cast
+ // instead of a select to synthesize the desired value.
+ bool IsOneZero = false;
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal))
+ IsOneZero = InitVal->isNullValue() && CI->isOne();
+
+ while (!GV->use_empty()) {
+ Instruction *UI = cast<Instruction>(GV->use_back());
+ if (StoreInst *SI = dyn_cast<StoreInst>(UI)) {
+ // Change the store into a boolean store.
+ bool StoringOther = SI->getOperand(0) == OtherVal;
+ // Only do this if we weren't storing a loaded value.
+ Value *StoreVal;
+ if (StoringOther || SI->getOperand(0) == InitVal)
+ StoreVal = ConstantInt::get(Type::Int1Ty, StoringOther);
+ else {
+ // Otherwise, we are storing a previously loaded copy. To do this,
+ // change the copy from copying the original value to just copying the
+ // bool.
+ Instruction *StoredVal = cast<Instruction>(SI->getOperand(0));
+
+ // If we're already replaced the input, StoredVal will be a cast or
+ // select instruction. If not, it will be a load of the original
+ // global.
+ if (LoadInst *LI = dyn_cast<LoadInst>(StoredVal)) {
+ assert(LI->getOperand(0) == GV && "Not a copy!");
+ // Insert a new load, to preserve the saved value.
+ StoreVal = new LoadInst(NewGV, LI->getName()+".b", LI);
+ } else {
+ assert((isa<CastInst>(StoredVal) || isa<SelectInst>(StoredVal)) &&
+ "This is not a form that we understand!");
+ StoreVal = StoredVal->getOperand(0);
+ assert(isa<LoadInst>(StoreVal) && "Not a load of NewGV!");
+ }
+ }
+ new StoreInst(StoreVal, NewGV, SI);
+ } else if (!UI->use_empty()) {
+ // Change the load into a load of bool then a select.
+ LoadInst *LI = cast<LoadInst>(UI);
+ LoadInst *NLI = new LoadInst(NewGV, LI->getName()+".b", LI);
+ Value *NSI;
+ if (IsOneZero)
+ NSI = new ZExtInst(NLI, LI->getType(), "", LI);
+ else
+ NSI = new SelectInst(NLI, OtherVal, InitVal, "", LI);
+ NSI->takeName(LI);
+ LI->replaceAllUsesWith(NSI);
+ }
+ UI->eraseFromParent();
+ }
+
+ GV->eraseFromParent();
+}
+
+
+/// 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) {
+ std::set<PHINode*> PHIUsers;
+ GlobalStatus GS;
+ GV->removeDeadConstantUsers();
+
+ if (GV->use_empty()) {
+ DOUT << "GLOBAL DEAD: " << *GV;
+ GV->eraseFromParent();
+ ++NumDeleted;
+ return true;
+ }
+
+ if (!AnalyzeGlobal(GV, GS, PHIUsers)) {
+#if 0
+ cerr << "Global: " << *GV;
+ cerr << " isLoaded = " << GS.isLoaded << "\n";
+ cerr << " StoredType = ";
+ switch (GS.StoredType) {
+ case GlobalStatus::NotStored: cerr << "NEVER STORED\n"; break;
+ case GlobalStatus::isInitializerStored: cerr << "INIT STORED\n"; break;
+ case GlobalStatus::isStoredOnce: cerr << "STORED ONCE\n"; break;
+ case GlobalStatus::isStored: cerr << "stored\n"; break;
+ }
+ if (GS.StoredType == GlobalStatus::isStoredOnce && GS.StoredOnceValue)
+ cerr << " StoredOnceValue = " << *GS.StoredOnceValue << "\n";
+ if (GS.AccessingFunction && !GS.HasMultipleAccessingFunctions)
+ cerr << " AccessingFunction = " << GS.AccessingFunction->getName()
+ << "\n";
+ cerr << " HasMultipleAccessingFunctions = "
+ << GS.HasMultipleAccessingFunctions << "\n";
+ cerr << " HasNonInstructionUser = " << GS.HasNonInstructionUser<<"\n";
+ cerr << " isNotSuitableForSRA = " << GS.isNotSuitableForSRA << "\n";
+ cerr << "\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 first class types since we
+ // are just replacing static memory to stack memory.
+ if (!GS.HasMultipleAccessingFunctions &&
+ GS.AccessingFunction && !GS.HasNonInstructionUser &&
+ GV->getType()->getElementType()->isFirstClassType() &&
+ GS.AccessingFunction->getName() == "main" &&
+ GS.AccessingFunction->hasExternalLinkage()) {
+ DOUT << "LOCALIZING GLOBAL: " << *GV;
+ Instruction* FirstI = 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) {
+ DOUT << "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;
+
+ } else if (GS.StoredType <= GlobalStatus::isInitializerStored) {
+ DOUT << "MARKING CONSTANT: " << *GV;
+ GV->setConstant(true);
+
+ // Clean up any obviously simplifiable users now.
+ CleanupConstantGlobalUsers(GV, GV->getInitializer());
+
+ // If the global is dead now, just nuke it.
+ if (GV->use_empty()) {
+ DOUT << " *** Marking constant allowed us to simplify "
+ << "all users and delete global!\n";
+ GV->eraseFromParent();
+ ++NumDeleted;
+ }
+
+ ++NumMarked;
+ return true;
+ } else if (!GS.isNotSuitableForSRA &&
+ !GV->getInitializer()->getType()->isFirstClassType()) {
+ if (GlobalVariable *FirstNewGV = SRAGlobal(GV)) {
+ 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 an undef 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()) {
+ DOUT << " *** 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,
+ getAnalysis<TargetData>()))
+ 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 (GV->getType()->getElementType() != Type::Int1Ty &&
+ !GV->getType()->getElementType()->isFloatingPoint() &&
+ !isa<VectorType>(GV->getType()->getElementType()) &&
+ !GS.HasPHIUser && !GS.isNotSuitableForSRA) {
+ DOUT << " *** SHRINKING TO BOOL: " << *GV;
+ ShrinkGlobalToBoolean(GV, SOVConstant);
+ ++NumShrunkToBool;
+ return true;
+ }
+ }
+ }
+ return false;
+}
+
+/// OnlyCalledDirectly - Return true if the specified function is only called
+/// directly. In other words, its address is never taken.
+static bool OnlyCalledDirectly(Function *F) {
+ for (Value::use_iterator UI = F->use_begin(), E = F->use_end(); UI != E;++UI){
+ Instruction *User = dyn_cast<Instruction>(*UI);
+ if (!User) return false;
+ if (!isa<CallInst>(User) && !isa<InvokeInst>(User)) return false;
+
+ // See if the function address is passed as an argument.
+ for (unsigned i = 1, e = User->getNumOperands(); i != e; ++i)
+ if (User->getOperand(i) == F) return false;
+ }
+ return true;
+}
+
+/// ChangeCalleesToFastCall - Walk all of the direct calls of the specified
+/// function, changing them to FastCC.
+static void ChangeCalleesToFastCall(Function *F) {
+ for (Value::use_iterator UI = F->use_begin(), E = F->use_end(); UI != E;++UI){
+ Instruction *User = cast<Instruction>(*UI);
+ if (CallInst *CI = dyn_cast<CallInst>(User))
+ CI->setCallingConv(CallingConv::Fast);
+ else
+ cast<InvokeInst>(User)->setCallingConv(CallingConv::Fast);
+ }
+}
+
+bool GlobalOpt::OptimizeFunctions(Module &M) {
+ bool Changed = false;
+ // Optimize functions.
+ for (Module::iterator FI = M.begin(), E = M.end(); FI != E; ) {
+ Function *F = FI++;
+ F->removeDeadConstantUsers();
+ if (F->use_empty() && (F->hasInternalLinkage() ||
+ F->hasLinkOnceLinkage())) {
+ M.getFunctionList().erase(F);
+ Changed = true;
+ ++NumFnDeleted;
+ } else if (F->hasInternalLinkage() &&
+ F->getCallingConv() == CallingConv::C && !F->isVarArg() &&
+ OnlyCalledDirectly(F)) {
+ // If this function has C calling conventions, is not a varargs
+ // function, and is only called directly, promote it to use the Fast
+ // calling convention.
+ F->setCallingConv(CallingConv::Fast);
+ ChangeCalleesToFastCall(F);
+ ++NumFastCallFns;
+ Changed = true;
+ }
+ }
+ return Changed;
+}
+
+bool GlobalOpt::OptimizeGlobalVars(Module &M) {
+ bool Changed = false;
+ for (Module::global_iterator GVI = M.global_begin(), E = M.global_end();
+ GVI != E; ) {
+ GlobalVariable *GV = GVI++;
+ if (!GV->isConstant() && GV->hasInternalLinkage() &&
+ GV->hasInitializer())
+ Changed |= ProcessInternalGlobal(GV, GVI);
+ }
+ return Changed;
+}
+
+/// 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) != Type::Int32Ty) 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() != Type::VoidTy || FTy->isVarArg() ||
+ FTy->getNumParams() != 0)
+ return 0;
+
+ // Verify that the initializer is simple enough for us to handle.
+ if (!I->hasInitializer()) return 0;
+ ConstantArray *CA = dyn_cast<ConstantArray>(I->getInitializer());
+ if (!CA) return 0;
+ for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i)
+ if (ConstantStruct *CS = dyn_cast<ConstantStruct>(CA->getOperand(i))) {
+ 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;
+ } else {
+ return 0;
+ }
+
+ return I;
+ }
+ return 0;
+}
+
+/// ParseGlobalCtors - Given a llvm.global_ctors list that we can understand,
+/// return a list of the functions and null terminator as a vector.
+static std::vector<Function*> ParseGlobalCtors(GlobalVariable *GV) {
+ ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
+ std::vector<Function*> Result;
+ Result.reserve(CA->getNumOperands());
+ for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i) {
+ ConstantStruct *CS = cast<ConstantStruct>(CA->getOperand(i));
+ Result.push_back(dyn_cast<Function>(CS->getOperand(1)));
+ }
+ return Result;
+}
+
+/// InstallGlobalCtors - Given a specified llvm.global_ctors list, install the
+/// specified array, returning the new global to use.
+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::Int32Ty, 65535));
+ CSVals.push_back(0);
+
+ // Create the new init list.
+ std::vector<Constant*> CAList;
+ for (unsigned i = 0, e = Ctors.size(); i != e; ++i) {
+ if (Ctors[i]) {
+ CSVals[1] = Ctors[i];
+ } else {
+ const Type *FTy = FunctionType::get(Type::VoidTy,
+ std::vector<const Type*>(), false);
+ const PointerType *PFTy = PointerType::get(FTy);
+ CSVals[1] = Constant::getNullValue(PFTy);
+ CSVals[0] = ConstantInt::get(Type::Int32Ty, 2147483647);
+ }
+ CAList.push_back(ConstantStruct::get(CSVals));
+ }
+
+ // Create the array initializer.
+ const Type *StructTy =
+ cast<ArrayType>(GCL->getType()->getElementType())->getElementType();
+ 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, "",
+ (Module *)NULL,
+ 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;
+ if (V->getType() != GCL->getType())
+ V = ConstantExpr::getBitCast(V, GCL->getType());
+ GCL->replaceAllUsesWith(V);
+ }
+ GCL->eraseFromParent();
+
+ if (Ctors.size())
+ return NGV;
+ else
+ return 0;
+}
+
+
+static Constant *getVal(std::map<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;
+}
+
+/// 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
+/// globals. This should be kept up to date with CommitValueTo.
+static bool isSimpleEnoughPointerToCommit(Constant *C) {
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) {
+ if (!GV->hasExternalLinkage() && !GV->hasInternalLinkage())
+ return false; // do not allow weak/linkonce/dllimport/dllexport linkage.
+ return !GV->isDeclaration(); // reject external globals.
+ }
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
+ // Handle a constantexpr gep.
+ if (CE->getOpcode() == Instruction::GetElementPtr &&
+ isa<GlobalVariable>(CE->getOperand(0))) {
+ GlobalVariable *GV = cast<GlobalVariable>(CE->getOperand(0));
+ if (!GV->hasExternalLinkage() && !GV->hasInternalLinkage())
+ return false; // do not allow weak/linkonce/dllimport/dllexport linkage.
+ return GV->hasInitializer() &&
+ ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE);
+ }
+ return false;
+}
+
+/// EvaluateStoreInto - Evaluate a piece of a constantexpr store into a global
+/// initializer. This returns 'Init' modified to reflect 'Val' stored into it.
+/// At this point, the GEP operands of Addr [0, OpNo) have been stepped into.
+static Constant *EvaluateStoreInto(Constant *Init, Constant *Val,
+ ConstantExpr *Addr, unsigned OpNo) {
+ // Base case of the recursion.
+ if (OpNo == Addr->getNumOperands()) {
+ assert(Val->getType() == Init->getType() && "Type mismatch!");
+ return Val;
+ }
+
+ if (const StructType *STy = dyn_cast<StructType>(Init->getType())) {
+ std::vector<Constant*> Elts;
+
+ // Break up the constant into its elements.
+ if (ConstantStruct *CS = dyn_cast<ConstantStruct>(Init)) {
+ for (unsigned i = 0, e = CS->getNumOperands(); i != e; ++i)
+ Elts.push_back(CS->getOperand(i));
+ } else if (isa<ConstantAggregateZero>(Init)) {
+ for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
+ Elts.push_back(Constant::getNullValue(STy->getElementType(i)));
+ } else if (isa<UndefValue>(Init)) {
+ for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
+ Elts.push_back(UndefValue::get(STy->getElementType(i)));
+ } else {
+ assert(0 && "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(&Elts[0], Elts.size(), STy->isPacked());
+ } else {
+ ConstantInt *CI = cast<ConstantInt>(Addr->getOperand(OpNo));
+ const ArrayType *ATy = cast<ArrayType>(Init->getType());
+
+ // Break up the array into elements.
+ std::vector<Constant*> Elts;
+ if (ConstantArray *CA = dyn_cast<ConstantArray>(Init)) {
+ for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i)
+ Elts.push_back(CA->getOperand(i));
+ } else if (isa<ConstantAggregateZero>(Init)) {
+ Constant *Elt = Constant::getNullValue(ATy->getElementType());
+ Elts.assign(ATy->getNumElements(), Elt);
+ } else if (isa<UndefValue>(Init)) {
+ Constant *Elt = UndefValue::get(ATy->getElementType());
+ Elts.assign(ATy->getNumElements(), Elt);
+ } else {
+ assert(0 && "This code is out of sync with "
+ " ConstantFoldLoadThroughGEPConstantExpr");
+ }
+
+ assert(CI->getZExtValue() < ATy->getNumElements());
+ Elts[CI->getZExtValue()] =
+ EvaluateStoreInto(Elts[CI->getZExtValue()], Val, Addr, OpNo+1);
+ return ConstantArray::get(ATy, Elts);
+ }
+}
+
+/// CommitValueTo - We have decided that Addr (which satisfies the predicate
+/// isSimpleEnoughPointerToCommit) should get Val as its value. Make it happen.
+static void CommitValueTo(Constant *Val, Constant *Addr) {
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
+ assert(GV->hasInitializer());
+ GV->setInitializer(Val);
+ return;
+ }
+
+ ConstantExpr *CE = cast<ConstantExpr>(Addr);
+ GlobalVariable *GV = cast<GlobalVariable>(CE->getOperand(0));
+
+ Constant *Init = GV->getInitializer();
+ Init = EvaluateStoreInto(Init, Val, CE, 2);
+ GV->setInitializer(Init);
+}
+
+/// ComputeLoadResult - Return the value that would be computed by a load from
+/// P after the stores reflected by 'memory' have been performed. If we can't
+/// decide, return null.
+static Constant *ComputeLoadResult(Constant *P,
+ const std::map<Constant*, Constant*> &Memory) {
+ // If this memory location has been recently stored, use the stored value: it
+ // is the most up-to-date.
+ std::map<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->hasInitializer())
+ return GV->getInitializer();
+ return 0;
+ }
+
+ // Handle a constantexpr getelementptr.
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(P))
+ if (CE->getOpcode() == Instruction::GetElementPtr &&
+ isa<GlobalVariable>(CE->getOperand(0))) {
+ GlobalVariable *GV = cast<GlobalVariable>(CE->getOperand(0));
+ if (GV->hasInitializer())
+ return ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE);
+ }
+
+ return 0; // don't know how to evaluate.
+}
+
+/// EvaluateFunction - Evaluate a call to function F, returning true if
+/// successful, false if we can't evaluate it. ActualArgs contains the formal
+/// arguments for the function.
+static bool EvaluateFunction(Function *F, Constant *&RetVal,
+ const std::vector<Constant*> &ActualArgs,
+ std::vector<Function*> &CallStack,
+ std::map<Constant*, Constant*> &MutatedMemory,
+ std::vector<GlobalVariable*> &AllocaTmps) {
+ // 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.
+ std::map<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;
+ ++AI, ++ArgNo)
+ Values[AI] = ActualArgs[ArgNo];
+
+ /// ExecutedBlocks - We only handle non-looping, non-recursive code. As such,
+ /// 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.
+ std::set<BasicBlock*> 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));
+ MutatedMemory[Ptr] = Val;
+ } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(CurInst)) {
+ InstResult = ConstantExpr::get(BO->getOpcode(),
+ getVal(Values, BO->getOperand(0)),
+ getVal(Values, BO->getOperand(1)));
+ } else if (CmpInst *CI = dyn_cast<CmpInst>(CurInst)) {
+ InstResult = ConstantExpr::getCompare(CI->getPredicate(),
+ getVal(Values, CI->getOperand(0)),
+ getVal(Values, CI->getOperand(1)));
+ } else if (CastInst *CI = dyn_cast<CastInst>(CurInst)) {
+ InstResult = ConstantExpr::getCast(CI->getOpcode(),
+ getVal(Values, CI->getOperand(0)),
+ CI->getType());
+ } else if (SelectInst *SI = dyn_cast<SelectInst>(CurInst)) {
+ InstResult = ConstantExpr::getSelect(getVal(Values, SI->getOperand(0)),
+ getVal(Values, SI->getOperand(1)),
+ getVal(Values, SI->getOperand(2)));
+ } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(CurInst)) {
+ Constant *P = getVal(Values, GEP->getOperand(0));
+ SmallVector<Constant*, 8> GEPOps;
+ for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
+ GEPOps.push_back(getVal(Values, GEP->getOperand(i)));
+ InstResult = ConstantExpr::getGetElementPtr(P, &GEPOps[0], GEPOps.size());
+ } else if (LoadInst *LI = dyn_cast<LoadInst>(CurInst)) {
+ if (LI->isVolatile()) return false; // no volatile accesses.
+ InstResult = ComputeLoadResult(getVal(Values, LI->getOperand(0)),
+ MutatedMemory);
+ if (InstResult == 0) return false; // Could not evaluate load.
+ } else if (AllocaInst *AI = dyn_cast<AllocaInst>(CurInst)) {
+ if (AI->isArrayAllocation()) return false; // Cannot handle array allocs.
+ const Type *Ty = AI->getType()->getElementType();
+ AllocaTmps.push_back(new GlobalVariable(Ty, false,
+ GlobalValue::InternalLinkage,
+ UndefValue::get(Ty),
+ AI->getName()));
+ InstResult = AllocaTmps.back();
+ } else if (CallInst *CI = dyn_cast<CallInst>(CurInst)) {
+ // Cannot handle inline asm.
+ if (isa<InlineAsm>(CI->getOperand(0))) return false;
+
+ // Resolve function pointers.
+ Function *Callee = dyn_cast<Function>(getVal(Values, CI->getOperand(0)));
+ if (!Callee) return false; // Cannot resolve.
+
+ std::vector<Constant*> Formals;
+ for (unsigned i = 1, e = CI->getNumOperands(); i != e; ++i)
+ Formals.push_back(getVal(Values, CI->getOperand(i)));
+
+ if (Callee->isDeclaration()) {
+ // If this is a function we can constant fold, do it.
+ if (Constant *C = ConstantFoldCall(Callee, &Formals[0],
+ Formals.size())) {
+ InstResult = C;
+ } else {
+ return false;
+ }
+ } 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))
+ return false;
+ InstResult = RetVal;
+ }
+ } else if (isa<TerminatorInst>(CurInst)) {
+ BasicBlock *NewBB = 0;
+ if (BranchInst *BI = dyn_cast<BranchInst>(CurInst)) {
+ if (BI->isUnconditional()) {
+ NewBB = BI->getSuccessor(0);
+ } else {
+ ConstantInt *Cond =
+ dyn_cast<ConstantInt>(getVal(Values, BI->getCondition()));
+ if (!Cond) return false; // Cannot determine.
+
+ NewBB = BI->getSuccessor(!Cond->getZExtValue());
+ }
+ } else if (SwitchInst *SI = dyn_cast<SwitchInst>(CurInst)) {
+ ConstantInt *Val =
+ dyn_cast<ConstantInt>(getVal(Values, SI->getCondition()));
+ if (!Val) return false; // Cannot determine.
+ NewBB = SI->getSuccessor(SI->findCaseValue(Val));
+ } 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).second)
+ 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.
+ BasicBlock *OldBB = CurInst->getParent();
+ CurInst = NewBB->begin();
+ PHINode *PN;
+ for (; (PN = dyn_cast<PHINode>(CurInst)); ++CurInst)
+ Values[PN] = getVal(Values, PN->getIncomingValueForBlock(OldBB));
+
+ // Do NOT increment CurInst. We know that the terminator had no value.
+ continue;
+ } else {
+ // Did not know how to evaluate this!
+ return false;
+ }
+
+ if (!CurInst->use_empty())
+ Values[CurInst] = InstResult;
+
+ // Advance program counter.
+ ++CurInst;
+ }
+}
+
+/// EvaluateStaticConstructor - Evaluate static constructors in the function, if
+/// we can. Return true if we can, false otherwise.
+static bool EvaluateStaticConstructor(Function *F) {
+ /// 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.
+ std::map<Constant*, Constant*> MutatedMemory;
+
+ /// AllocaTmps - To 'execute' an alloca, we create a temporary global variable
+ /// 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;
+
+ // Call the function.
+ Constant *RetValDummy;
+ bool EvalSuccess = EvaluateFunction(F, RetValDummy, std::vector<Constant*>(),
+ CallStack, MutatedMemory, AllocaTmps);
+ if (EvalSuccess) {
+ // We succeeded at evaluation: commit the result.
+ DOUT << "FULLY EVALUATED GLOBAL CTOR FUNCTION '"
+ << F->getName() << "' to " << MutatedMemory.size()
+ << " stores.\n";
+ for (std::map<Constant*, Constant*>::iterator I = MutatedMemory.begin(),
+ 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.
+ if (!Tmp->use_empty())
+ Tmp->replaceAllUsesWith(Constant::getNullValue(Tmp->getType()));
+ delete Tmp;
+ }
+
+ return EvalSuccess;
+}
+
+
+
+/// OptimizeGlobalCtorsList - Simplify and evaluation global ctors if possible.
+/// Return true if anything changed.
+bool GlobalOpt::OptimizeGlobalCtorsList(GlobalVariable *&GCL) {
+ std::vector<Function*> Ctors = ParseGlobalCtors(GCL);
+ bool MadeChange = false;
+ if (Ctors.empty()) return false;
+
+ // Loop over global ctors, optimizing them when we can.
+ for (unsigned i = 0; i != Ctors.size(); ++i) {
+ Function *F = Ctors[i];
+ // Found a null terminator in the middle of the list, prune off the rest of
+ // the list.
+ if (F == 0) {
+ if (i != Ctors.size()-1) {
+ Ctors.resize(i+1);
+ MadeChange = true;
+ }
+ break;
+ }
+
+ // We cannot simplify external ctor functions.
+ if (F->empty()) continue;
+
+ // If we can evaluate the ctor at compile time, do.
+ if (EvaluateStaticConstructor(F)) {
+ Ctors.erase(Ctors.begin()+i);
+ MadeChange = true;
+ --i;
+ ++NumCtorsEvaluated;
+ continue;
+ }
+ }
+
+ if (!MadeChange) return false;
+
+ GCL = InstallGlobalCtors(GCL, Ctors);
+ return true;
+}
+
+
+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);
+ Changed |= LocalChange;
+ }
+
+ // TODO: Move all global ctors functions to the end of the module for code
+ // layout.
+
+ return Changed;
+}