#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"
Statistic<> NumLocalized("globalopt", "Number of globals localized");
Statistic<> NumShrunkToBool("globalopt",
"Number of global vars shrunk to booleans");
+ Statistic<> NumFastCallFns("globalopt",
+ "Number of functions converted to fastcc");
+ Statistic<> NumEmptyCtor ("globalopt", "Number of empty ctors removed");
+ Statistic<> NumCtorsEvaluated("globalopt","Number of static ctors evaluated");
struct GlobalOpt : public ModulePass {
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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);
};
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;
+
/// 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.
GlobalStatus() : isLoaded(false), StoredType(NotStored), StoredOnceValue(0),
AccessingFunction(0), HasMultipleAccessingFunctions(false),
- isNotSuitableForSRA(false) {}
+ HasNonInstructionUser(false), isNotSuitableForSRA(false) {}
};
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;
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 {
- // Otherwise must be a global or some other user.
+ GS.HasNonInstructionUser = true;
+ // Otherwise must be some other user.
return true;
}
return 0;
}
-static Constant *TraverseGEPInitializer(User *GEP, Constant *Init) {
- if (Init == 0) return 0;
- if (GEP->getNumOperands() == 1 ||
- !isa<Constant>(GEP->getOperand(1)) ||
- !cast<Constant>(GEP->getOperand(1))->isNullValue())
- return 0;
-
- for (unsigned i = 2, e = GEP->getNumOperands(); i != e; ++i) {
- ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(i));
- if (!Idx) return 0;
- Init = getAggregateConstantElement(Init, Idx);
- if (Init == 0) return 0;
- }
- return Init;
-}
/// CleanupConstantGlobalUsers - We just marked GV constant. Loop over all
/// users of the global, cleaning up the obvious ones. This is largely just a
Changed = true;
} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) {
if (CE->getOpcode() == Instruction::GetElementPtr) {
- Constant *SubInit = TraverseGEPInitializer(CE, Init);
+ Constant *SubInit = 0;
+ if (Init)
+ SubInit = ConstantFoldLoadThroughGEPConstantExpr(Init, CE);
Changed |= CleanupConstantGlobalUsers(CE, SubInit);
} else if (CE->getOpcode() == Instruction::Cast &&
isa<PointerType>(CE->getType())) {
Changed = true;
}
} else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(U)) {
- Constant *SubInit = TraverseGEPInitializer(GEP, Init);
+ Constant *SubInit = 0;
+ ConstantExpr *CE =
+ dyn_cast_or_null<ConstantExpr>(ConstantFoldInstruction(GEP));
+ if (CE && CE->getOpcode() == Instruction::GetElementPtr)
+ SubInit = ConstantFoldLoadThroughGEPConstantExpr(Init, CE);
Changed |= CleanupConstantGlobalUsers(GEP, SubInit);
if (GEP->use_empty()) {
// 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.AccessingFunction && !GS.HasNonInstructionUser &&
GV->getType()->getElementType()->isFirstClassType() &&
GS.AccessingFunction->getName() == "main" &&
GS.AccessingFunction->hasExternalLinkage()) {
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;
+}
-bool GlobalOpt::runOnModule(Module &M) {
+/// 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;
+}
- // As a prepass, delete functions that are trivially dead.
- bool LocalChange = true;
- while (LocalChange) {
- LocalChange = false;
- 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);
- LocalChange = true;
- ++NumFnDeleted;
+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::giterator 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::IntTy) 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->getRawValue() != 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(ConstantSInt::get(Type::IntTy, 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] = ConstantSInt::get(Type::IntTy, 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,
+ GCL->getName());
+ GCL->setName("");
+ GCL->getParent()->getGlobalList().insert(GCL, NGV);
+
+ // 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::getCast(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))
+ return !GV->isExternal(); // 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));
+ 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.
+ ConstantUInt *CU = cast<ConstantUInt>(Addr->getOperand(OpNo));
+ assert(CU->getValue() < STy->getNumElements() &&
+ "Struct index out of range!");
+ unsigned Idx = (unsigned)CU->getValue();
+ Elts[Idx] = EvaluateStoreInto(Elts[Idx], Val, Addr, OpNo+1);
+
+ // Return the modified struct.
+ return ConstantStruct::get(Elts);
+ } 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((uint64_t)CI->getRawValue() < ATy->getNumElements());
+ Elts[(uint64_t)CI->getRawValue()] =
+ EvaluateStoreInto(Elts[(uint64_t)CI->getRawValue()], 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.
+}
+
+/// EvaluateStaticConstructor - Evaluate static constructors in the function, if
+/// we can. Return true if we can, false otherwise.
+static bool EvaluateStaticConstructor(Function *F) {
+ /// Values - As we compute SSA register values, we store their contents here.
+ std::map<Value*, Constant*> Values;
+
+ /// 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;
+
+ /// 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;
+
+ /// AllocaTmps - To 'execute' an alloca, we create a temporary global variable
+ /// to represent its body. This allows us to delete the temporary globals
+ /// when we are done.
+ std::vector<GlobalVariable*> AllocaTmps;
+
+ // CurInst - The current instruction we're evaluating.
+ BasicBlock::iterator CurInst = F->begin()->begin();
+ ExecutedBlocks.insert(F->begin());
+
+ bool EvaluationSuccessful = false;
+
+ // This is the main evaluation loop.
+ while (1) {
+ Constant *InstResult = 0;
+
+ if (StoreInst *SI = dyn_cast<StoreInst>(CurInst)) {
+ if (SI->isVolatile()) break; // no volatile accesses.
+ Constant *Ptr = getVal(Values, SI->getOperand(1));
+ if (!isSimpleEnoughPointerToCommit(Ptr))
+ // If this is too complex for us to commit, reject it.
+ break;
+ 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 (ShiftInst *SI = dyn_cast<ShiftInst>(CurInst)) {
+ InstResult = ConstantExpr::get(SI->getOpcode(),
+ getVal(Values, SI->getOperand(0)),
+ getVal(Values, SI->getOperand(1)));
+ } else if (CastInst *CI = dyn_cast<CastInst>(CurInst)) {
+ InstResult = ConstantExpr::getCast(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));
+ std::vector<Constant*> GEPOps;
+ for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
+ GEPOps.push_back(getVal(Values, GEP->getOperand(i)));
+ InstResult = ConstantExpr::getGetElementPtr(P, GEPOps);
+ } else if (LoadInst *LI = dyn_cast<LoadInst>(CurInst)) {
+ if (LI->isVolatile()) break; // no volatile accesses.
+ InstResult = ComputeLoadResult(getVal(Values, LI->getOperand(0)),
+ MutatedMemory);
+ if (InstResult == 0) break; // Could not evaluate load.
+ } else if (AllocaInst *AI = dyn_cast<AllocaInst>(CurInst)) {
+ if (AI->isArrayAllocation()) break; // 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 (TerminatorInst *TI = dyn_cast<TerminatorInst>(CurInst)) {
+ BasicBlock *NewBB = 0;
+ if (BranchInst *BI = dyn_cast<BranchInst>(CurInst)) {
+ if (BI->isUnconditional()) {
+ NewBB = BI->getSuccessor(0);
+ } else {
+ ConstantBool *Cond =
+ dyn_cast<ConstantBool>(getVal(Values, BI->getCondition()));
+ if (!Cond) break; // Cannot determine.
+ NewBB = BI->getSuccessor(!Cond->getValue());
+ }
+ } else if (SwitchInst *SI = dyn_cast<SwitchInst>(CurInst)) {
+ ConstantInt *Val =
+ dyn_cast<ConstantInt>(getVal(Values, SI->getCondition()));
+ if (!Val) break; // Cannot determine.
+ NewBB = SI->getSuccessor(SI->findCaseValue(Val));
+ } else if (ReturnInst *RI = dyn_cast<ReturnInst>(CurInst)) {
+ assert(RI->getNumOperands() == 0);
+ EvaluationSuccessful = true;
+ break; // We succeeded at evaluating this ctor!
+ } else {
+ // unwind, unreachable.
+ break; // 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 or recursive
+ // function, which we cannot evaluate in reasonable time.
+ if (!ExecutedBlocks.insert(NewBB).second)
+ break; // Recursed/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 {
+ // TODO: use ConstantFoldCall for function calls.
+
+ // Did not know how to evaluate this!
+ break;
}
- Changed |= LocalChange;
+
+ if (!CurInst->use_empty())
+ Values[CurInst] = InstResult;
+
+ // Advance program counter.
+ ++CurInst;
+ }
+
+ if (EvaluationSuccessful) {
+ // We succeeded at evaluation: commit the result.
+ DEBUG(std::cerr << "FULLY EVALUATED GLOBAL CTOR FUNCTION '" <<
+ F->getName() << "'\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 EvaluationSuccessful;
+}
+
- LocalChange = true;
+/// 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 the function is empty, just remove it from the ctor list.
+ if (isa<ReturnInst>(F->begin()->getTerminator()) &&
+ &F->begin()->front() == F->begin()->getTerminator()) {
+ Ctors.erase(Ctors.begin()+i);
+ MadeChange = true;
+ --i;
+ ++NumEmptyCtor;
+ 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;
- for (Module::global_iterator GVI = M.global_begin(), E = M.global_end(); GVI != E;) {
- GlobalVariable *GV = GVI++;
- if (!GV->isConstant() && GV->hasInternalLinkage() &&
- GV->hasInitializer())
- LocalChange |= ProcessInternalGlobal(GV, GVI);
- }
+
+ // 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;
}
projects / oota-llvm.git / blobdiff