#include "llvm/Instructions.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/Module.h"
+#include "llvm/Operator.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetLibraryInfo.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
using namespace llvm;
STATISTIC(NumMarked , "Number of globals marked constant");
+STATISTIC(NumUnnamed , "Number of globals marked unnamed_addr");
STATISTIC(NumSRA , "Number of aggregate globals broken into scalars");
STATISTIC(NumHeapSRA , "Number of heap objects SRA'd");
STATISTIC(NumSubstitute,"Number of globals with initializers stored into them");
STATISTIC(NumNestRemoved , "Number of nest attributes removed");
STATISTIC(NumAliasesResolved, "Number of global aliases resolved");
STATISTIC(NumAliasesRemoved, "Number of global aliases eliminated");
+STATISTIC(NumCXXDtorsRemoved, "Number of global C++ destructors removed");
namespace {
+ struct GlobalStatus;
struct GlobalOpt : public ModulePass {
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<TargetLibraryInfo>();
}
static char ID; // Pass identification, replacement for typeid
- GlobalOpt() : ModulePass(ID) {}
+ GlobalOpt() : ModulePass(ID) {
+ initializeGlobalOptPass(*PassRegistry::getPassRegistry());
+ }
bool runOnModule(Module &M);
bool OptimizeGlobalVars(Module &M);
bool OptimizeGlobalAliases(Module &M);
bool OptimizeGlobalCtorsList(GlobalVariable *&GCL);
- bool ProcessInternalGlobal(GlobalVariable *GV,Module::global_iterator &GVI);
+ bool ProcessGlobal(GlobalVariable *GV,Module::global_iterator &GVI);
+ bool ProcessInternalGlobal(GlobalVariable *GV,Module::global_iterator &GVI,
+ const SmallPtrSet<const PHINode*, 16> &PHIUsers,
+ const GlobalStatus &GS);
+ bool OptimizeEmptyGlobalCXXDtors(Function *CXAAtExitFn);
+
+ TargetData *TD;
+ TargetLibraryInfo *TLI;
};
}
char GlobalOpt::ID = 0;
-INITIALIZE_PASS(GlobalOpt, "globalopt",
- "Global Variable Optimizer", false, false);
+INITIALIZE_PASS_BEGIN(GlobalOpt, "globalopt",
+ "Global Variable Optimizer", false, false)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
+INITIALIZE_PASS_END(GlobalOpt, "globalopt",
+ "Global Variable Optimizer", false, false)
ModulePass *llvm::createGlobalOptimizerPass() { return new GlobalOpt(); }
/// about it. If we find out that the address of the global is taken, none of
/// this info will be accurate.
struct GlobalStatus {
+ /// isCompared - True if the global's address is used in a comparison.
+ bool isCompared;
+
/// isLoaded - True if the global is ever loaded. If the global isn't ever
/// loaded it can be deleted.
bool isLoaded;
/// HasPHIUser - Set to true if this global has a user that is a PHI node.
bool HasPHIUser;
-
- GlobalStatus() : isLoaded(false), StoredType(NotStored), StoredOnceValue(0),
- AccessingFunction(0), HasMultipleAccessingFunctions(false),
- HasNonInstructionUser(false), HasPHIUser(false) {}
+
+ /// AtomicOrdering - Set to the strongest atomic ordering requirement.
+ AtomicOrdering Ordering;
+
+ GlobalStatus() : isCompared(false), isLoaded(false), StoredType(NotStored),
+ StoredOnceValue(0), AccessingFunction(0),
+ HasMultipleAccessingFunctions(false),
+ HasNonInstructionUser(false), HasPHIUser(false),
+ Ordering(NotAtomic) {}
};
}
-// SafeToDestroyConstant - It is safe to destroy a constant iff it is only used
-// by constants itself. Note that constants cannot be cyclic, so this test is
-// pretty easy to implement recursively.
-//
+/// StrongerOrdering - Return the stronger of the two ordering. If the two
+/// orderings are acquire and release, then return AcquireRelease.
+///
+static AtomicOrdering StrongerOrdering(AtomicOrdering X, AtomicOrdering Y) {
+ if (X == Acquire && Y == Release) return AcquireRelease;
+ if (Y == Acquire && X == Release) return AcquireRelease;
+ return (AtomicOrdering)std::max(X, Y);
+}
+
+/// SafeToDestroyConstant - It is safe to destroy a constant iff it is only used
+/// by constants itself. Note that constants cannot be cyclic, so this test is
+/// pretty easy to implement recursively.
+///
static bool SafeToDestroyConstant(const Constant *C) {
if (isa<GlobalValue>(C)) return false;
const User *U = *UI;
if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) {
GS.HasNonInstructionUser = true;
+
+ // If the result of the constantexpr isn't pointer type, then we won't
+ // know to expect it in various places. Just reject early.
+ if (!isa<PointerType>(CE->getType())) return true;
+
if (AnalyzeGlobal(CE, GS, PHIUsers)) return true;
} else if (const Instruction *I = dyn_cast<Instruction>(U)) {
if (!GS.HasMultipleAccessingFunctions) {
}
if (const LoadInst *LI = dyn_cast<LoadInst>(I)) {
GS.isLoaded = true;
- if (LI->isVolatile()) return true; // Don't hack on volatile loads.
+ // Don't hack on volatile loads.
+ if (LI->isVolatile()) return true;
+ GS.Ordering = StrongerOrdering(GS.Ordering, LI->getOrdering());
} else if (const 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 (SI->isVolatile()) return true; // Don't hack on volatile stores.
+ // Don't hack on volatile stores.
+ if (SI->isVolatile()) return true;
+ GS.Ordering = StrongerOrdering(GS.Ordering, SI->getOrdering());
// 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
if (AnalyzeGlobal(I, GS, PHIUsers)) return true;
GS.HasPHIUser = true;
} else if (isa<CmpInst>(I)) {
- // Nothing to analyse.
- } else if (isa<MemTransferInst>(I)) {
- const MemTransferInst *MTI = cast<MemTransferInst>(I);
+ GS.isCompared = true;
+ } else if (const MemTransferInst *MTI = dyn_cast<MemTransferInst>(I)) {
+ if (MTI->isVolatile()) return true;
if (MTI->getArgOperand(0) == V)
GS.StoredType = GlobalStatus::isStored;
if (MTI->getArgOperand(1) == V)
GS.isLoaded = true;
- } else if (isa<MemSetInst>(I)) {
- assert(cast<MemSetInst>(I)->getArgOperand(0) == V &&
- "Memset only takes one pointer!");
+ } else if (const MemSetInst *MSI = dyn_cast<MemSetInst>(I)) {
+ assert(MSI->getArgOperand(0) == V && "Memset only takes one pointer!");
+ if (MSI->isVolatile()) return true;
GS.StoredType = GlobalStatus::isStored;
} else {
return true; // Any other non-load instruction might take address!
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) {
+static bool CleanupConstantGlobalUsers(Value *V, Constant *Init,
+ TargetData *TD, TargetLibraryInfo *TLI) {
bool Changed = false;
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;) {
User *U = *UI++;
Constant *SubInit = 0;
if (Init)
SubInit = ConstantFoldLoadThroughGEPConstantExpr(Init, CE);
- Changed |= CleanupConstantGlobalUsers(CE, SubInit);
- } else if (CE->getOpcode() == Instruction::BitCast &&
+ Changed |= CleanupConstantGlobalUsers(CE, SubInit, TD, TLI);
+ } else if (CE->getOpcode() == Instruction::BitCast &&
CE->getType()->isPointerTy()) {
// Pointer cast, delete any stores and memsets to the global.
- Changed |= CleanupConstantGlobalUsers(CE, 0);
+ Changed |= CleanupConstantGlobalUsers(CE, 0, TD, TLI);
}
if (CE->use_empty()) {
// and will invalidate our notion of what Init is.
Constant *SubInit = 0;
if (!isa<ConstantExpr>(GEP->getOperand(0))) {
- ConstantExpr *CE =
- dyn_cast_or_null<ConstantExpr>(ConstantFoldInstruction(GEP));
+ ConstantExpr *CE =
+ dyn_cast_or_null<ConstantExpr>(ConstantFoldInstruction(GEP, TD, TLI));
if (Init && CE && CE->getOpcode() == Instruction::GetElementPtr)
SubInit = ConstantFoldLoadThroughGEPConstantExpr(Init, CE);
}
- Changed |= CleanupConstantGlobalUsers(GEP, SubInit);
+ Changed |= CleanupConstantGlobalUsers(GEP, SubInit, TD, TLI);
if (GEP->use_empty()) {
GEP->eraseFromParent();
if (SafeToDestroyConstant(C)) {
C->destroyConstant();
// This could have invalidated UI, start over from scratch.
- CleanupConstantGlobalUsers(V, Init);
+ CleanupConstantGlobalUsers(V, Init, TD, TLI);
return true;
}
}
// We might have a dead and dangling constant hanging off of here.
if (Constant *C = dyn_cast<Constant>(V))
return SafeToDestroyConstant(C);
-
+
Instruction *I = dyn_cast<Instruction>(V);
if (!I) return false;
// Stores *to* the pointer are ok.
if (StoreInst *SI = dyn_cast<StoreInst>(I))
return SI->getOperand(0) != V;
-
+
// Otherwise, it must be a GEP.
GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I);
if (GEPI == 0) return false;
-
+
if (GEPI->getNumOperands() < 3 || !isa<Constant>(GEPI->getOperand(1)) ||
!cast<Constant>(GEPI->getOperand(1))->isNullValue())
return false;
-
+
for (Value::use_iterator I = GEPI->use_begin(), E = GEPI->use_end();
I != E; ++I)
if (!isSafeSROAElementUse(*I))
///
static bool IsUserOfGlobalSafeForSRA(User *U, GlobalValue *GV) {
// The user of the global must be a GEP Inst or a ConstantExpr GEP.
- if (!isa<GetElementPtrInst>(U) &&
- (!isa<ConstantExpr>(U) ||
+ if (!isa<GetElementPtrInst>(U) &&
+ (!isa<ConstantExpr>(U) ||
cast<ConstantExpr>(U)->getOpcode() != Instruction::GetElementPtr))
return false;
-
+
// Check to see if this ConstantExpr GEP is SRA'able. In particular, we
// don't like < 3 operand CE's, and we don't like non-constant integer
// indices. This enforces that all uses are 'gep GV, 0, C, ...' for some
gep_type_iterator GEPI = gep_type_begin(U), E = gep_type_end(U);
++GEPI; // Skip over the pointer index.
-
+
// If this is a use of an array allocation, do a bit more checking for sanity.
- if (
const ArrayType *AT = dyn_cast<ArrayType>(*GEPI)) {
+ if (ArrayType *AT = dyn_cast<ArrayType>(*GEPI)) {
uint64_t NumElements = AT->getNumElements();
ConstantInt *Idx = cast<ConstantInt>(U->getOperand(2));
-
+
// Check to make sure that index falls within the array. If not,
// something funny is going on, so we won't do the optimization.
//
if (Idx->getZExtValue() >= NumElements)
return false;
-
+
// We cannot scalar repl this level of the array unless any array
// sub-indices are in-range constants. In particular, consider:
// A[0][i]. We cannot know that the user isn't doing invalid things like
GEPI != E;
++GEPI) {
uint64_t NumElements;
- if (
const ArrayType *SubArrayTy = dyn_cast<ArrayType>(*GEPI))
+ if (ArrayType *SubArrayTy = dyn_cast<ArrayType>(*GEPI))
NumElements = SubArrayTy->getNumElements();
- else if (const VectorType *SubVectorTy = dyn_cast<VectorType>(*GEPI))
+ else if (VectorType *SubVectorTy = dyn_cast<VectorType>(*GEPI))
NumElements = SubVectorTy->getNumElements();
else {
assert((*GEPI)->isStructTy() &&
"Indexed GEP type is not array, vector, or struct!");
continue;
}
-
+
ConstantInt *IdxVal = dyn_cast<ConstantInt>(GEPI.getOperand());
if (!IdxVal || IdxVal->getZExtValue() >= NumElements)
return false;
}
return true;
}
-
+
/// SRAGlobal - Perform scalar replacement of aggregates on the specified global
/// variable. This opens the door for other optimizations by exposing the
// Make sure this global only has simple uses that we can SRA.
if (!GlobalUsersSafeToSRA(GV))
return 0;
-
+
assert(GV->hasLocalLinkage() && !GV->isConstant());
Constant *Init = GV->getInitializer();
- const Type *Ty = Init->getType();
+ Type *Ty = Init->getType();
std::vector<GlobalVariable*> NewGlobals;
Module::GlobalListType &Globals = GV->getParent()->getGlobalList();
unsigned StartAlignment = GV->getAlignment();
if (StartAlignment == 0)
StartAlignment = TD.getABITypeAlignment(GV->getType());
-
- if (const StructType *STy = dyn_cast<StructType>(Ty)) {
+
+ if (StructType *STy = dyn_cast<StructType>(Ty)) {
NewGlobals.reserve(STy->getNumElements());
const StructLayout &Layout = *TD.getStructLayout(STy);
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
- Constant *In = getAggregateConstantElement(Init,
- ConstantInt::get(Type::getInt32Ty(STy->getContext()), i));
+ Constant *In = Init->getAggregateElement(i);
assert(In && "Couldn't get element of initializer?");
GlobalVariable *NGV = new GlobalVariable(STy->getElementType(i), false,
GlobalVariable::InternalLinkage,
GV->getType()->getAddressSpace());
Globals.insert(GV, NGV);
NewGlobals.push_back(NGV);
-
+
// Calculate the known alignment of the field. If the original aggregate
// had 256 byte alignment for example, something might depend on that:
// propagate info to each field.
if (NewAlign > TD.getABITypeAlignment(STy->getElementType(i)))
NGV->setAlignment(NewAlign);
}
- } else if (const SequentialType *STy = dyn_cast<SequentialType>(Ty)) {
+ } else if (SequentialType *STy = dyn_cast<SequentialType>(Ty)) {
unsigned NumElements = 0;
- if (
const ArrayType *ATy = dyn_cast<ArrayType>(STy))
+ if (ArrayType *ATy = dyn_cast<ArrayType>(STy))
NumElements = ATy->getNumElements();
else
NumElements = cast<VectorType>(STy)->getNumElements();
if (NumElements > 16 && GV->hasNUsesOrMore(16))
return 0; // It's not worth it.
NewGlobals.reserve(NumElements);
-
+
uint64_t EltSize = TD.getTypeAllocSize(STy->getElementType());
unsigned EltAlign = TD.getABITypeAlignment(STy->getElementType());
for (unsigned i = 0, e = NumElements; i != e; ++i) {
- Constant *In = getAggregateConstantElement(Init,
- ConstantInt::get(Type::getInt32Ty(Init->getContext()), i));
+ Constant *In = Init->getAggregateElement(i);
assert(In && "Couldn't get element of initializer?");
GlobalVariable *NGV = new GlobalVariable(STy->getElementType(), false,
GV->getType()->getAddressSpace());
Globals.insert(GV, NGV);
NewGlobals.push_back(NGV);
-
+
// Calculate the known alignment of the field. If the original aggregate
// had 256 byte alignment for example, something might depend on that:
// propagate info to each field.
if (NewGlobals.empty())
return 0;
-
+
DEBUG(dbgs() << "PERFORMING GLOBAL SRA ON: " << *GV);
Constant *NullInt =Constant::getNullValue(Type::getInt32Ty(GV->getContext()));
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());
+ NewPtr = ConstantExpr::getGetElementPtr(cast<Constant>(NewPtr), Idxs);
} 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 = GetElementPtrInst::Create(NewPtr, Idxs.begin(), Idxs.end(),
+ NewPtr = GetElementPtrInst::Create(NewPtr, Idxs,
GEPI->getName()+"."+Twine(Val),GEPI);
}
}
}
/// AllUsesOfValueWillTrapIfNull - Return true if all users of the specified
-/// value will trap if the value is dynamically null. PHIs keeps track of any
+/// value will trap if the value is dynamically null. PHIs keeps track of any
/// phi nodes we've seen to avoid reprocessing them.
static bool AllUsesOfValueWillTrapIfNull(const Value *V,
SmallPtrSet<const PHINode*, 8> &PHIs) {
break;
if (Idxs.size() == GEPI->getNumOperands()-1)
Changed |= OptimizeAwayTrappingUsesOfValue(GEPI,
- ConstantExpr::getGetElementPtr(NewV, &Idxs[0],
- Idxs.size()));
+ ConstantExpr::getGetElementPtr(NewV, Idxs));
if (GEPI->use_empty()) {
Changed = true;
GEPI->eraseFromParent();
/// 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) {
+static bool OptimizeAwayTrappingUsesOfLoads(GlobalVariable *GV, Constant *LV,
+ TargetData *TD,
+ TargetLibraryInfo *TLI) {
bool Changed = false;
// Keep track of whether we are able to remove all the uses of the global
// other than the store that defines it.
bool AllNonStoreUsesGone = true;
-
+
// Replace all uses of loads with uses of uses of the stored value.
for (Value::use_iterator GUI = GV->use_begin(), E = GV->use_end(); GUI != E;){
User *GlobalUser = *GUI++;
// If we get here we could have other crazy uses that are transitively
// loaded.
assert((isa<PHINode>(GlobalUser) || isa<SelectInst>(GlobalUser) ||
- isa<ConstantExpr>(GlobalUser)) && "Only expect load and stores!");
+ isa<ConstantExpr>(GlobalUser) || isa<CmpInst>(GlobalUser)) &&
+ "Only expect load and stores!");
}
}
// nor is the global.
if (AllNonStoreUsesGone) {
DEBUG(dbgs() << " *** GLOBAL NOW DEAD!\n");
- CleanupConstantGlobalUsers(GV, 0);
+ CleanupConstantGlobalUsers(GV, 0, TD, TLI);
if (GV->use_empty()) {
GV->eraseFromParent();
++NumDeleted;
/// ConstantPropUsersOf - Walk the use list of V, constant folding all of the
/// instructions that are foldable.
-static void ConstantPropUsersOf(Value *V) {
+static void ConstantPropUsersOf(Value *V,
+ TargetData *TD, TargetLibraryInfo *TLI) {
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)) {
+ if (Constant *NewC = ConstantFoldInstruction(I, TD, TLI)) {
I->replaceAllUsesWith(NewC);
// Advance UI to the next non-I use to avoid invalidating it!
/// malloc into a global, and any loads of GV as uses of the new global.
static GlobalVariable *OptimizeGlobalAddressOfMalloc(GlobalVariable *GV,
CallInst *CI,
- const Type *AllocTy,
+ Type *AllocTy,
ConstantInt *NElements,
- TargetData* TD) {
+ TargetData *TD,
+ TargetLibraryInfo *TLI) {
DEBUG(errs() << "PROMOTING GLOBAL: " << *GV << " CALL = " << *CI << '\n');
-
- const Type *GlobalType;
+
+ Type *GlobalType;
if (NElements->getZExtValue() == 1)
GlobalType = AllocTy;
else
// Create the new global variable. The contents of the malloc'd memory is
// undefined, so initialize with an undef value.
- GlobalVariable *NewGV = new GlobalVariable(*GV->getParent(),
+ GlobalVariable *NewGV = new GlobalVariable(*GV->getParent(),
GlobalType, false,
GlobalValue::InternalLinkage,
UndefValue::get(GlobalType),
GV->getName()+".body",
GV,
GV->isThreadLocal());
-
+
// If there are bitcast users of the malloc (which is typical, usually we have
// a malloc + bitcast) then replace them with uses of the new global. Update
// other users to use the global as well.
User->replaceUsesOfWith(CI, TheBC);
}
}
-
+
Constant *RepValue = NewGV;
if (NewGV->getType() != GV->getType()->getElementType())
- RepValue = ConstantExpr::getBitCast(RepValue,
+ RepValue = ConstantExpr::getBitCast(RepValue,
GV->getType()->getElementType());
// If there is a comparison against null, we will insert a global bool to
while (!GV->use_empty()) {
if (StoreInst *SI = dyn_cast<StoreInst>(GV->use_back())) {
// The global is initialized when the store to it occurs.
- new StoreInst(ConstantInt::getTrue(GV->getContext()), InitBool, SI);
+ new StoreInst(ConstantInt::getTrue(GV->getContext()), InitBool, false, 0,
+ SI->getOrdering(), SI->getSynchScope(), SI);
SI->eraseFromParent();
continue;
}
-
+
LoadInst *LI = cast<LoadInst>(GV->use_back());
while (!LI->use_empty()) {
Use &LoadUse = LI->use_begin().getUse();
LoadUse = RepValue;
continue;
}
-
+
ICmpInst *ICI = cast<ICmpInst>(LoadUse.getUser());
// Replace the cmp X, 0 with a use of the bool value.
- Value *LV = new LoadInst(InitBool, InitBool->getName()+".val", ICI);
+ // Sink the load to where the compare was, if atomic rules allow us to.
+ Value *LV = new LoadInst(InitBool, InitBool->getName()+".val", false, 0,
+ LI->getOrdering(), LI->getSynchScope(),
+ LI->isUnordered() ? (Instruction*)ICI : LI);
InitBoolUsed = true;
switch (ICI->getPredicate()) {
default: llvm_unreachable("Unknown ICmp Predicate!");
// 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);
+ ConstantPropUsersOf(NewGV, TD, TLI);
if (RepValue != NewGV)
- ConstantPropUsersOf(RepValue);
+ ConstantPropUsersOf(RepValue, TD, TLI);
return NewGV;
}
if (isa<LoadInst>(Inst) || isa<CmpInst>(Inst)) {
continue; // Fine, ignore.
}
-
+
if (const StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
if (SI->getOperand(0) == V && SI->getOperand(1) != GV)
return false; // Storing the pointer itself... bad.
continue; // Otherwise, storing through it, or storing into GV... fine.
}
-
+
// Must index into the array and into the struct.
if (isa<GetElementPtrInst>(Inst) && Inst->getNumOperands() >= 3) {
if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(Inst, GV, PHIs))
return false;
continue;
}
-
+
if (const PHINode *PN = dyn_cast<PHINode>(Inst)) {
// PHIs are ok if all uses are ok. Don't infinitely recurse through PHI
// cycles.
return false;
continue;
}
-
+
if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Inst)) {
if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(BCI, GV, PHIs))
return false;
continue;
}
-
+
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
+/// GV. This assumes that these value pass the
/// 'ValueIsOnlyUsedLocallyOrStoredToOneGlobal' predicate.
-static void ReplaceUsesOfMallocWithGlobal(Instruction *Alloc,
+static void ReplaceUsesOfMallocWithGlobal(Instruction *Alloc,
GlobalVariable *GV) {
while (!Alloc->use_empty()) {
Instruction *U = cast<Instruction>(*Alloc->use_begin());
continue;
}
}
-
+
// Insert a load from the global, and use it instead of the malloc.
Value *NL = new LoadInst(GV, GV->getName()+".val", InsertPt);
U->replaceUsesOfWith(Alloc, NL);
for (Value::const_use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;
++UI) {
const Instruction *User = cast<Instruction>(*UI);
-
+
// Comparison against null is ok.
if (const ICmpInst *ICI = dyn_cast<ICmpInst>(User)) {
if (!isa<ConstantPointerNull>(ICI->getOperand(1)))
return false;
continue;
}
-
+
// getelementptr is also ok, but only a simple form.
if (const GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User)) {
// Must index into the array and into the struct.
if (GEPI->getNumOperands() < 3)
return false;
-
+
// Otherwise the GEP is ok.
continue;
}
-
+
if (const PHINode *PN = dyn_cast<PHINode>(User)) {
if (!LoadUsingPHIsPerLoad.insert(PN))
// This means some phi nodes are dependent on each other.
if (!LoadUsingPHIs.insert(PN))
// If we have already analyzed this PHI, then it is safe.
continue;
-
+
// Make sure all uses of the PHI are simple enough to transform.
if (!LoadUsesSimpleEnoughForHeapSRA(PN,
LoadUsingPHIs, LoadUsingPHIsPerLoad))
return false;
-
+
continue;
}
-
+
// Otherwise we don't know what this is, not ok.
return false;
}
-
+
return true;
}
return false;
LoadUsingPHIsPerLoad.clear();
}
-
+
// If we reach here, we know that all uses of the loads and transitive uses
// (through PHI nodes) are simple enough to transform. However, we don't know
- // that all inputs the to the PHI nodes are in the same equivalence sets.
+ // that all inputs the to the PHI nodes are in the same equivalence sets.
// Check to verify that all operands of the PHIs are either PHIS that can be
// transformed, loads from GV, or MI itself.
for (SmallPtrSet<const PHINode*, 32>::const_iterator I = LoadUsingPHIs.begin()
const PHINode *PN = *I;
for (unsigned op = 0, e = PN->getNumIncomingValues(); op != e; ++op) {
Value *InVal = PN->getIncomingValue(op);
-
+
// PHI of the stored value itself is ok.
if (InVal == StoredVal) continue;
-
+
if (const PHINode *InPN = dyn_cast<PHINode>(InVal)) {
// One of the PHIs in our set is (optimistically) ok.
if (LoadUsingPHIs.count(InPN))
continue;
return false;
}
-
+
// Load from GV is ok.
if (const LoadInst *LI = dyn_cast<LoadInst>(InVal))
if (LI->getOperand(0) == GV)
continue;
-
+
// UNDEF? NULL?
-
+
// Anything else is rejected.
return false;
}
}
-
+
return true;
}
DenseMap<Value*, std::vector<Value*> > &InsertedScalarizedValues,
std::vector<std::pair<PHINode*, unsigned> > &PHIsToRewrite) {
std::vector<Value*> &FieldVals = InsertedScalarizedValues[V];
-
+
if (FieldNo >= FieldVals.size())
FieldVals.resize(FieldNo+1);
-
+
// If we already have this value, just reuse the previously scalarized
// version.
if (Value *FieldVal = FieldVals[FieldNo])
return FieldVal;
-
+
// Depending on what instruction this is, we have several cases.
Value *Result;
if (LoadInst *LI = dyn_cast<LoadInst>(V)) {
} else if (PHINode *PN = dyn_cast<PHINode>(V)) {
// PN's type is pointer to struct. Make a new PHI of pointer to struct
// field.
- const StructType *ST =
+ StructType *ST =
cast<StructType>(cast<PointerType>(PN->getType())->getElementType());
-
- Result =
+
+ PHINode *NewPN =
PHINode::Create(PointerType::getUnqual(ST->getElementType(FieldNo)),
+ PN->getNumIncomingValues(),
PN->getName()+".f"+Twine(FieldNo), PN);
+ Result = NewPN;
PHIsToRewrite.push_back(std::make_pair(PN, FieldNo));
} else {
llvm_unreachable("Unknown usable value");
- Result = 0;
}
-
+
return FieldVals[FieldNo] = Result;
}
/// RewriteHeapSROALoadUser - Given a load instruction and a value derived from
/// the load, rewrite the derived value to use the HeapSRoA'd load.
-static void RewriteHeapSROALoadUser(Instruction *LoadUser,
+static void RewriteHeapSROALoadUser(Instruction *LoadUser,
DenseMap<Value*, std::vector<Value*> > &InsertedScalarizedValues,
std::vector<std::pair<PHINode*, unsigned> > &PHIsToRewrite) {
// If this is a comparison against null, handle it.
// field.
Value *NPtr = GetHeapSROAValue(SCI->getOperand(0), 0,
InsertedScalarizedValues, PHIsToRewrite);
-
+
Value *New = new ICmpInst(SCI, SCI->getPredicate(), NPtr,
- Constant::getNullValue(NPtr->getType()),
+ Constant::getNullValue(NPtr->getType()),
SCI->getName());
SCI->replaceAllUsesWith(New);
SCI->eraseFromParent();
return;
}
-
+
// Handle 'getelementptr Ptr, Idx, i32 FieldNo ...'
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(LoadUser)) {
assert(GEPI->getNumOperands() >= 3 && isa<ConstantInt>(GEPI->getOperand(2))
&& "Unexpected GEPI!");
-
+
// Load the pointer for this field.
unsigned FieldNo = cast<ConstantInt>(GEPI->getOperand(2))->getZExtValue();
Value *NewPtr = GetHeapSROAValue(GEPI->getOperand(0), FieldNo,
InsertedScalarizedValues, PHIsToRewrite);
-
+
// Create the new GEP idx vector.
SmallVector<Value*, 8> GEPIdx;
GEPIdx.push_back(GEPI->getOperand(1));
GEPIdx.append(GEPI->op_begin()+3, GEPI->op_end());
-
- Value *NGEPI = GetElementPtrInst::Create(NewPtr,
- GEPIdx.begin(), GEPIdx.end(),
+
+ Value *NGEPI = GetElementPtrInst::Create(NewPtr, GEPIdx,
GEPI->getName(), GEPI);
GEPI->replaceAllUsesWith(NGEPI);
GEPI->eraseFromParent();
// already been seen first by another load, so its uses have already been
// processed.
PHINode *PN = cast<PHINode>(LoadUser);
- bool Inserted;
- DenseMap<Value*, std::vector<Value*> >::iterator InsertPos;
- tie(InsertPos, Inserted) =
- InsertedScalarizedValues.insert(std::make_pair(PN, std::vector<Value*>()));
- if (!Inserted) return;
-
+ if (!InsertedScalarizedValues.insert(std::make_pair(PN,
+ std::vector<Value*>())).second)
+ return;
+
// If this is the first time we've seen this PHI, recursively process all
// users.
for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end(); UI != E; ) {
/// is a value loaded from the global. Eliminate all uses of Ptr, making them
/// use FieldGlobals instead. All uses of loaded values satisfy
/// AllGlobalLoadUsesSimpleEnoughForHeapSRA.
-static void RewriteUsesOfLoadForHeapSRoA(LoadInst *Load,
+static void RewriteUsesOfLoadForHeapSRoA(LoadInst *Load,
DenseMap<Value*, std::vector<Value*> > &InsertedScalarizedValues,
std::vector<std::pair<PHINode*, unsigned> > &PHIsToRewrite) {
for (Value::use_iterator UI = Load->use_begin(), E = Load->use_end();
Instruction *User = cast<Instruction>(*UI++);
RewriteHeapSROALoadUser(User, InsertedScalarizedValues, PHIsToRewrite);
}
-
+
if (Load->use_empty()) {
Load->eraseFromParent();
InsertedScalarizedValues.erase(Load);
/// PerformHeapAllocSRoA - CI is an allocation of an array of structures. Break
/// it up into multiple allocations of arrays of the fields.
static GlobalVariable *PerformHeapAllocSRoA(GlobalVariable *GV, CallInst *CI,
- Value* NElems, TargetData *TD) {
+ Value *NElems, TargetData *TD) {
DEBUG(dbgs() << "SROA HEAP ALLOC: " << *GV << " MALLOC = " << *CI << '\n');
- const Type* MAT = getMallocAllocatedType(CI);
- const StructType *STy = cast<StructType>(MAT);
+ Type *MAT = getMallocAllocatedType(CI);
+ StructType *STy = cast<StructType>(MAT);
// 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
// new mallocs at the same place as CI, and N globals.
std::vector<Value*> FieldGlobals;
std::vector<Value*> FieldMallocs;
-
+
for (unsigned FieldNo = 0, e = STy->getNumElements(); FieldNo != e;++FieldNo){
- const Type *FieldTy = STy->getElementType(FieldNo);
- const PointerType *PFieldTy = PointerType::getUnqual(FieldTy);
-
+ Type *FieldTy = STy->getElementType(FieldNo);
+ PointerType *PFieldTy = PointerType::getUnqual(FieldTy);
+
GlobalVariable *NGV =
new GlobalVariable(*GV->getParent(),
PFieldTy, false, GlobalValue::InternalLinkage,
GV->getName() + ".f" + Twine(FieldNo), GV,
GV->isThreadLocal());
FieldGlobals.push_back(NGV);
-
+
unsigned TypeSize = TD->getTypeAllocSize(FieldTy);
- if (const StructType *ST = dyn_cast<StructType>(FieldTy))
+ if (StructType *ST = dyn_cast<StructType>(FieldTy))
TypeSize = TD->getStructLayout(ST)->getSizeInBytes();
- const Type *IntPtrTy = TD->getIntPtrType(CI->getContext());
+ Type *IntPtrTy = TD->getIntPtrType(CI->getContext());
Value *NMI = CallInst::CreateMalloc(CI, IntPtrTy, FieldTy,
ConstantInt::get(IntPtrTy, TypeSize),
NElems, 0,
FieldMallocs.push_back(NMI);
new StoreInst(NMI, NGV, CI);
}
-
+
// The tricky aspect of this transformation is handling the case when malloc
// fails. In the original code, malloc failing would set the result pointer
// of malloc to null. In this case, some mallocs could succeed and others
// Split the basic block at the old malloc.
BasicBlock *OrigBB = CI->getParent();
BasicBlock *ContBB = OrigBB->splitBasicBlock(CI, "malloc_cont");
-
+
// Create the block to check the first condition. Put all these blocks at the
// end of the function as they are unlikely to be executed.
BasicBlock *NullPtrBlock = BasicBlock::Create(OrigBB->getContext(),
"malloc_ret_null",
OrigBB->getParent());
-
+
// Remove the uncond branch from OrigBB to ContBB, turning it into a cond
// branch on RunningOr.
OrigBB->getTerminator()->eraseFromParent();
BranchInst::Create(NullPtrBlock, ContBB, RunningOr, OrigBB);
-
+
// Within the NullPtrBlock, we need to emit a comparison and branch for each
// pointer, because some may be null while others are not.
for (unsigned i = 0, e = FieldGlobals.size(); i != e; ++i) {
Value *GVVal = new LoadInst(FieldGlobals[i], "tmp", NullPtrBlock);
- Value *Cmp = new ICmpInst(*NullPtrBlock, ICmpInst::ICMP_NE, GVVal,
- Constant::getNullValue(GVVal->getType()),
- "tmp");
+ Value *Cmp = new ICmpInst(*NullPtrBlock, ICmpInst::ICMP_NE, GVVal,
+ Constant::getNullValue(GVVal->getType()));
BasicBlock *FreeBlock = BasicBlock::Create(Cmp->getContext(), "free_it",
OrigBB->getParent());
BasicBlock *NextBlock = BasicBlock::Create(Cmp->getContext(), "next",
new StoreInst(Constant::getNullValue(GVVal->getType()), FieldGlobals[i],
FreeBlock);
BranchInst::Create(NextBlock, FreeBlock);
-
+
NullPtrBlock = NextBlock;
}
-
+
BranchInst::Create(ContBB, NullPtrBlock);
// CI is no longer needed, remove it.
/// inserted for a given load.
DenseMap<Value*, std::vector<Value*> > InsertedScalarizedValues;
InsertedScalarizedValues[GV] = FieldGlobals;
-
+
std::vector<std::pair<PHINode*, unsigned> > PHIsToRewrite;
-
+
// Okay, the malloc site is completely handled. All of the uses of GV are now
// loads, and all uses of those loads are simple. Rewrite them to use loads
// of the per-field globals instead.
for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end(); UI != E;) {
Instruction *User = cast<Instruction>(*UI++);
-
+
if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
RewriteUsesOfLoadForHeapSRoA(LI, InsertedScalarizedValues, PHIsToRewrite);
continue;
}
-
+
// Must be a store of null.
StoreInst *SI = cast<StoreInst>(User);
assert(isa<ConstantPointerNull>(SI->getOperand(0)) &&
"Unexpected heap-sra user!");
-
+
// Insert a store of null into each global.
for (unsigned i = 0, e = FieldGlobals.size(); i != e; ++i) {
-
const PointerType *PT = cast<PointerType>(FieldGlobals[i]->getType());
+ PointerType *PT = cast<PointerType>(FieldGlobals[i]->getType());
Constant *Null = Constant::getNullValue(PT->getElementType());
new StoreInst(Null, FieldGlobals[i], SI);
}
FieldPN->addIncoming(InVal, PN->getIncomingBlock(i));
}
}
-
+
// Drop all inter-phi links and any loads that made it this far.
for (DenseMap<Value*, std::vector<Value*> >::iterator
I = InsertedScalarizedValues.begin(), E = InsertedScalarizedValues.end();
else if (LoadInst *LI = dyn_cast<LoadInst>(I->first))
LI->dropAllReferences();
}
-
+
// Delete all the phis and loads now that inter-references are dead.
for (DenseMap<Value*, std::vector<Value*> >::iterator
I = InsertedScalarizedValues.begin(), E = InsertedScalarizedValues.end();
else if (LoadInst *LI = dyn_cast<LoadInst>(I->first))
LI->eraseFromParent();
}
-
+
// The old global is now dead, remove it.
GV->eraseFromParent();
/// cast of malloc.
static bool TryToOptimizeStoreOfMallocToGlobal(GlobalVariable *GV,
CallInst *CI,
- const Type *AllocTy,
+ Type *AllocTy,
+ AtomicOrdering Ordering,
Module::global_iterator &GVI,
- TargetData *TD) {
+ TargetData *TD,
+ TargetLibraryInfo *TLI) {
if (!TD)
return false;
-
+
// If this is a malloc of an abstract type, don't touch it.
if (!AllocTy->isSized())
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
+ // malloc to be stored into the specified global, loaded icmp'd, and
// GEP'd. These are all things we could transform to using the global
// for.
SmallPtrSet<const PHINode*, 8> PHIs;
// (2048 bytes currently), as we don't want to introduce a 16M global or
// something.
if (NElements->getZExtValue() * TD->getTypeAllocSize(AllocTy) < 2048) {
- GVI = OptimizeGlobalAddressOfMalloc(GV, CI, AllocTy, NElements, TD);
+ GVI = OptimizeGlobalAddressOfMalloc(GV, CI, AllocTy, NElements, TD, TLI);
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 (Ordering != NotAtomic)
+ return false;
+
// If this is an allocation of a fixed size array of structs, analyze as a
// variable size array. malloc [100 x struct],1 -> malloc struct, 100
if (NElems == ConstantInt::get(CI->getArgOperand(0)->getType(), 1))
- if (
const ArrayType *AT = dyn_cast<ArrayType>(AllocTy))
+ if (ArrayType *AT = dyn_cast<ArrayType>(AllocTy))
AllocTy = AT->getElementType();
- const StructType *AllocSTy = dyn_cast<StructType>(AllocTy);
+ StructType *AllocSTy = dyn_cast<StructType>(AllocTy);
if (!AllocSTy)
return false;
// If this is a fixed size array, transform the Malloc to be an alloc of
// structs. malloc [100 x struct],1 -> malloc struct, 100
- if (
const ArrayType *AT = dyn_cast<ArrayType>(getMallocAllocatedType(CI))) {
- const Type *IntPtrTy = TD->getIntPtrType(CI->getContext());
+ if (ArrayType *AT = dyn_cast<ArrayType>(getMallocAllocatedType(CI))) {
+ Type *IntPtrTy = TD->getIntPtrType(CI->getContext());
unsigned TypeSize = TD->getStructLayout(AllocSTy)->getSizeInBytes();
Value *AllocSize = ConstantInt::get(IntPtrTy, TypeSize);
Value *NumElements = ConstantInt::get(IntPtrTy, AT->getNumElements());
CI = dyn_cast<BitCastInst>(Malloc) ?
extractMallocCallFromBitCast(Malloc) : cast<CallInst>(Malloc);
}
-
- GVI = PerformHeapAllocSRoA(GV, CI, getMallocArraySize(CI, TD, true),TD);
+
+ GVI = PerformHeapAllocSRoA(GV, CI, getMallocArraySize(CI, TD, true), TD);
return true;
}
-
+
return false;
-}
+}
// OptimizeOnceStoredGlobal - Try to optimize globals based on the knowledge
// that only one value (besides its initializer) is ever stored to the global.
static bool OptimizeOnceStoredGlobal(GlobalVariable *GV, Value *StoredOnceVal,
+ AtomicOrdering Ordering,
Module::global_iterator &GVI,
- TargetData *TD) {
+ TargetData *TD, TargetLibraryInfo *TLI) {
// Ignore no-op GEPs and bitcasts.
StoredOnceVal = StoredOnceVal->stripPointerCasts();
GV->getInitializer()->isNullValue()) {
if (Constant *SOVC = dyn_cast<Constant>(StoredOnceVal)) {
if (GV->getInitializer()->getType() != SOVC->getType())
- SOVC =
- ConstantExpr::getBitCast(SOVC, GV->getInitializer()->getType());
+ SOVC = ConstantExpr::getBitCast(SOVC, GV->getInitializer()->getType());
// Optimize away any trapping uses of the loaded value.
- if (OptimizeAwayTrappingUsesOfLoads(GV, SOVC))
+ if (OptimizeAwayTrappingUsesOfLoads(GV, SOVC, TD, TLI))
return true;
} else if (CallInst *CI = extractMallocCall(StoredOnceVal)) {
- const Type* MallocType = getMallocAllocatedType(CI);
- if (MallocType && TryToOptimizeStoreOfMallocToGlobal(GV, CI, MallocType,
- GVI, TD))
+ Type *MallocType = getMallocAllocatedType(CI);
+ if (MallocType &&
+ TryToOptimizeStoreOfMallocToGlobal(GV, CI, MallocType, Ordering, GVI,
+ TD, TLI))
return true;
}
}
/// can shrink the global into a boolean and select between the two values
/// whenever it is used. This exposes the values to other scalar optimizations.
static bool TryToShrinkGlobalToBoolean(GlobalVariable *GV, Constant *OtherVal) {
- const Type *GVElType = GV->getType()->getElementType();
-
+ Type *GVElType = GV->getType()->getElementType();
+
// If GVElType is already i1, it is already shrunk. If the type of the GV is
// an FP value, pointer or vector, don't do this optimization because a select
// between them is very expensive and unlikely to lead to later
}
DEBUG(dbgs() << " *** SHRINKING TO BOOL: " << *GV);
-
+
// Create the new global, initializing it to false.
GlobalVariable *NewGV = new GlobalVariable(Type::getInt1Ty(GV->getContext()),
false,
- GlobalValue::InternalLinkage,
+ GlobalValue::InternalLinkage,
ConstantInt::getFalse(GV->getContext()),
GV->getName()+".b",
GV->isThreadLocal());
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);
+ StoreVal = new LoadInst(NewGV, LI->getName()+".b", false, 0,
+ LI->getOrdering(), LI->getSynchScope(), LI);
} else {
assert((isa<CastInst>(StoredVal) || isa<SelectInst>(StoredVal)) &&
"This is not a form that we understand!");
assert(isa<LoadInst>(StoreVal) && "Not a load of NewGV!");
}
}
- new StoreInst(StoreVal, NewGV, SI);
+ new StoreInst(StoreVal, NewGV, false, 0,
+ SI->getOrdering(), SI->getSynchScope(), SI);
} else {
// 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);
+ LoadInst *NLI = new LoadInst(NewGV, LI->getName()+".b", false, 0,
+ LI->getOrdering(), LI->getSynchScope(), LI);
Value *NSI;
if (IsOneZero)
NSI = new ZExtInst(NLI, LI->getType(), "", LI);
}
-/// ProcessInternalGlobal - Analyze the specified global variable and optimize
-/// it if possible. If we make a change, return true.
-bool GlobalOpt::ProcessInternalGlobal(GlobalVariable *GV,
- Module::global_iterator &GVI) {
- SmallPtrSet<const PHINode*, 16> PHIUsers;
- GlobalStatus GS;
+/// ProcessGlobal - Analyze the specified global variable and optimize it if
+/// possible. If we make a change, return true.
+bool GlobalOpt::ProcessGlobal(GlobalVariable *GV,
+ Module::global_iterator &GVI) {
+ if (!GV->hasLocalLinkage())
+ return false;
+
+ // Do more involved optimizations if the global is internal.
GV->removeDeadConstantUsers();
if (GV->use_empty()) {
return true;
}
- if (!AnalyzeGlobal(GV, GS, PHIUsers)) {
-#if 0
- DEBUG(dbgs() << "Global: " << *GV);
- DEBUG(dbgs() << " isLoaded = " << GS.isLoaded << "\n");
- DEBUG(dbgs() << " StoredType = ");
- switch (GS.StoredType) {
- case GlobalStatus::NotStored: DEBUG(dbgs() << "NEVER STORED\n"); break;
- case GlobalStatus::isInitializerStored: DEBUG(dbgs() << "INIT STORED\n");
- break;
- case GlobalStatus::isStoredOnce: DEBUG(dbgs() << "STORED ONCE\n"); break;
- case GlobalStatus::isStored: DEBUG(dbgs() << "stored\n"); break;
- }
- if (GS.StoredType == GlobalStatus::isStoredOnce && GS.StoredOnceValue)
- DEBUG(dbgs() << " StoredOnceValue = " << *GS.StoredOnceValue << "\n");
- if (GS.AccessingFunction && !GS.HasMultipleAccessingFunctions)
- DEBUG(dbgs() << " AccessingFunction = "
- << GS.AccessingFunction->getName() << "\n");
- DEBUG(dbgs() << " HasMultipleAccessingFunctions = "
- << GS.HasMultipleAccessingFunctions << "\n");
- DEBUG(dbgs() << " HasNonInstructionUser = "
- << GS.HasNonInstructionUser<<"\n");
- DEBUG(dbgs() << "\n");
-#endif
-
- // If this is a first class global and has only one accessing function
- // and this function is main (which we know is not recursive we can make
- // this global a local variable) we replace the global with a local alloca
- // in this function.
- //
- // NOTE: It doesn't make sense to promote non single-value types since we
- // are just replacing static memory to stack memory.
- //
- // If the global is in different address space, don't bring it to stack.
- if (!GS.HasMultipleAccessingFunctions &&
- GS.AccessingFunction && !GS.HasNonInstructionUser &&
- GV->getType()->getElementType()->isSingleValueType() &&
- GS.AccessingFunction->getName() == "main" &&
- GS.AccessingFunction->hasExternalLinkage() &&
- GV->getType()->getAddressSpace() == 0) {
- DEBUG(dbgs() << "LOCALIZING GLOBAL: " << *GV);
- Instruction& FirstI = const_cast<Instruction&>(*GS.AccessingFunction
- ->getEntryBlock().begin());
- const Type* ElemTy = GV->getType()->getElementType();
- // FIXME: Pass Global's alignment when globals have alignment
- AllocaInst* Alloca = new AllocaInst(ElemTy, NULL, GV->getName(), &FirstI);
- if (!isa<UndefValue>(GV->getInitializer()))
- new StoreInst(GV->getInitializer(), Alloca, &FirstI);
-
- GV->replaceAllUsesWith(Alloca);
+ SmallPtrSet<const PHINode*, 16> PHIUsers;
+ GlobalStatus GS;
+
+ if (AnalyzeGlobal(GV, GS, PHIUsers))
+ return false;
+
+ if (!GS.isCompared && !GV->hasUnnamedAddr()) {
+ GV->setUnnamedAddr(true);
+ NumUnnamed++;
+ }
+
+ if (GV->isConstant() || !GV->hasInitializer())
+ return false;
+
+ return ProcessInternalGlobal(GV, GVI, PHIUsers, GS);
+}
+
+/// ProcessInternalGlobal - Analyze the specified global variable and optimize
+/// it if possible. If we make a change, return true.
+bool GlobalOpt::ProcessInternalGlobal(GlobalVariable *GV,
+ Module::global_iterator &GVI,
+ const SmallPtrSet<const PHINode*, 16> &PHIUsers,
+ const GlobalStatus &GS) {
+ // If this is a first class global and has only one accessing function
+ // and this function is main (which we know is not recursive we can make
+ // this global a local variable) we replace the global with a local alloca
+ // in this function.
+ //
+ // NOTE: It doesn't make sense to promote non single-value types since we
+ // are just replacing static memory to stack memory.
+ //
+ // If the global is in different address space, don't bring it to stack.
+ if (!GS.HasMultipleAccessingFunctions &&
+ GS.AccessingFunction && !GS.HasNonInstructionUser &&
+ GV->getType()->getElementType()->isSingleValueType() &&
+ GS.AccessingFunction->getName() == "main" &&
+ GS.AccessingFunction->hasExternalLinkage() &&
+ GV->getType()->getAddressSpace() == 0) {
+ DEBUG(dbgs() << "LOCALIZING GLOBAL: " << *GV);
+ Instruction &FirstI = const_cast<Instruction&>(*GS.AccessingFunction
+ ->getEntryBlock().begin());
+ Type *ElemTy = GV->getType()->getElementType();
+ // FIXME: Pass Global's alignment when globals have alignment
+ AllocaInst *Alloca = new AllocaInst(ElemTy, NULL, GV->getName(), &FirstI);
+ if (!isa<UndefValue>(GV->getInitializer()))
+ new StoreInst(GV->getInitializer(), Alloca, &FirstI);
+
+ GV->replaceAllUsesWith(Alloca);
+ GV->eraseFromParent();
+ ++NumLocalized;
+ return true;
+ }
+
+ // If the global is never loaded (but may be stored to), it is dead.
+ // Delete it now.
+ if (!GS.isLoaded) {
+ DEBUG(dbgs() << "GLOBAL NEVER LOADED: " << *GV);
+
+ // Delete any stores we can find to the global. We may not be able to
+ // make it completely dead though.
+ bool Changed = CleanupConstantGlobalUsers(GV, GV->getInitializer(),
+ TD, TLI);
+
+ // If the global is dead now, delete it.
+ if (GV->use_empty()) {
GV->eraseFromParent();
- ++NumLocalized;
- return true;
+ ++NumDeleted;
+ Changed = true;
}
-
- // If the global is never loaded (but may be stored to), it is dead.
- // Delete it now.
- if (!GS.isLoaded) {
- DEBUG(dbgs() << "GLOBAL NEVER LOADED: " << *GV);
-
- // Delete any stores we can find to the global. We may not be able to
- // make it completely dead though.
- bool Changed = CleanupConstantGlobalUsers(GV, GV->getInitializer());
-
- // If the global is dead now, delete it.
- if (GV->use_empty()) {
- GV->eraseFromParent();
- ++NumDeleted;
- Changed = true;
- }
- return Changed;
+ return Changed;
+
+ } else if (GS.StoredType <= GlobalStatus::isInitializerStored) {
+ DEBUG(dbgs() << "MARKING CONSTANT: " << *GV);
+ GV->setConstant(true);
- } else if (GS.StoredType <= GlobalStatus::isInitializerStored) {
- DEBUG(dbgs() << "MARKING CONSTANT: " << *GV);
- GV->setConstant(true);
+ // Clean up any obviously simplifiable users now.
+ CleanupConstantGlobalUsers(GV, GV->getInitializer(), TD, TLI);
- // Clean up any obviously simplifiable users now.
- CleanupConstantGlobalUsers(GV, GV->getInitializer());
+ // If the global is dead now, just nuke it.
+ if (GV->use_empty()) {
+ DEBUG(dbgs() << " *** Marking constant allowed us to simplify "
+ << "all users and delete global!\n");
+ GV->eraseFromParent();
+ ++NumDeleted;
+ }
- // If the global is dead now, just nuke it.
- if (GV->use_empty()) {
- DEBUG(dbgs() << " *** Marking constant allowed us to simplify "
- << "all users and delete global!\n");
- GV->eraseFromParent();
- ++NumDeleted;
+ ++NumMarked;
+ return true;
+ } else if (!GV->getInitializer()->getType()->isSingleValueType()) {
+ if (TargetData *TD = getAnalysisIfAvailable<TargetData>())
+ if (GlobalVariable *FirstNewGV = SRAGlobal(GV, *TD)) {
+ GVI = FirstNewGV; // Don't skip the newly produced globals!
+ return true;
+ }
+ } else if (GS.StoredType == GlobalStatus::isStoredOnce) {
+ // If the initial value for the global was an undef value, and if only
+ // one other value was stored into it, we can just change the
+ // initializer to be the stored value, then delete all stores to the
+ // global. This allows us to mark it constant.
+ if (Constant *SOVConstant = dyn_cast<Constant>(GS.StoredOnceValue))
+ if (isa<UndefValue>(GV->getInitializer())) {
+ // Change the initial value here.
+ GV->setInitializer(SOVConstant);
+
+ // Clean up any obviously simplifiable users now.
+ CleanupConstantGlobalUsers(GV, GV->getInitializer(), TD, TLI);
+
+ if (GV->use_empty()) {
+ DEBUG(dbgs() << " *** Substituting initializer allowed us to "
+ << "simplify all users and delete global!\n");
+ GV->eraseFromParent();
+ ++NumDeleted;
+ } else {
+ GVI = GV;
+ }
+ ++NumSubstitute;
+ return true;
}
- ++NumMarked;
+ // Try to optimize globals based on the knowledge that only one value
+ // (besides its initializer) is ever stored to the global.
+ if (OptimizeOnceStoredGlobal(GV, GS.StoredOnceValue, GS.Ordering, GVI,
+ TD, TLI))
return true;
- } else if (!GV->getInitializer()->getType()->isSingleValueType()) {
- if (TargetData *TD = getAnalysisIfAvailable<TargetData>())
- if (GlobalVariable *FirstNewGV = SRAGlobal(GV, *TD)) {
- GVI = FirstNewGV; // Don't skip the newly produced globals!
- return true;
- }
- } else if (GS.StoredType == GlobalStatus::isStoredOnce) {
- // If the initial value for the global was an undef value, and if only
- // one other value was stored into it, we can just change the
- // initializer to be the stored value, then delete all stores to the
- // global. This allows us to mark it constant.
- if (Constant *SOVConstant = dyn_cast<Constant>(GS.StoredOnceValue))
- if (isa<UndefValue>(GV->getInitializer())) {
- // Change the initial value here.
- GV->setInitializer(SOVConstant);
-
- // Clean up any obviously simplifiable users now.
- CleanupConstantGlobalUsers(GV, GV->getInitializer());
-
- if (GV->use_empty()) {
- DEBUG(dbgs() << " *** Substituting initializer allowed us to "
- << "simplify all users and delete global!\n");
- GV->eraseFromParent();
- ++NumDeleted;
- } else {
- GVI = GV;
- }
- ++NumSubstitute;
- return true;
- }
- // Try to optimize globals based on the knowledge that only one value
- // (besides its initializer) is ever stored to the global.
- if (OptimizeOnceStoredGlobal(GV, GS.StoredOnceValue, GVI,
- getAnalysisIfAvailable<TargetData>()))
+ // Otherwise, if the global was not a boolean, we can shrink it to be a
+ // boolean.
+ if (Constant *SOVConstant = dyn_cast<Constant>(GS.StoredOnceValue))
+ if (TryToShrinkGlobalToBoolean(GV, SOVConstant)) {
+ ++NumShrunkToBool;
return true;
-
- // Otherwise, if the global was not a boolean, we can shrink it to be a
- // boolean.
- if (Constant *SOVConstant = dyn_cast<Constant>(GS.StoredOnceValue))
- if (TryToShrinkGlobalToBoolean(GV, SOVConstant)) {
- ++NumShrunkToBool;
- return true;
- }
- }
+ }
}
+
return false;
}
if (!F->hasName() && !F->isDeclaration())
F->setLinkage(GlobalValue::InternalLinkage);
F->removeDeadConstantUsers();
- if (F->use_empty() && (F->hasLocalLinkage() || F->hasLinkOnceLinkage())) {
+ if (F->isDefTriviallyDead()) {
F->eraseFromParent();
Changed = true;
++NumFnDeleted;
// Simplify the initializer.
if (GV->hasInitializer())
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(GV->getInitializer())) {
- TargetData *TD = getAnalysisIfAvailable<TargetData>();
- Constant *New = ConstantFoldConstantExpression(CE, TD);
+ Constant *New = ConstantFoldConstantExpression(CE, TD, TLI);
if (New && New != CE)
GV->setInitializer(New);
}
- // Do more involved optimizations if the global is internal.
- if (!GV->isConstant() && GV->hasLocalLinkage() &&
- GV->hasInitializer())
- Changed |= ProcessInternalGlobal(GV, GVI);
+
+ Changed |= ProcessGlobal(GV, GVI);
}
return Changed;
}
-/// FindGlobalCtors - Find the llvm.globalctors list, verifying that all
+/// FindGlobalCtors - Find the llvm.global_ctors list, verifying that all
/// initializers have an init priority of 65535.
GlobalVariable *GlobalOpt::FindGlobalCtors(Module &M) {
- for (Module::global_iterator I = M.global_begin(), E = M.global_end();
- I != E; ++I)
- if (I->getName() == "llvm.global_ctors") {
- // Found it, verify it's an array of { int, void()* }.
- const ArrayType *ATy =dyn_cast<ArrayType>(I->getType()->getElementType());
- if (!ATy) return 0;
- const StructType *STy = dyn_cast<StructType>(ATy->getElementType());
- if (!STy || STy->getNumElements() != 2 ||
- !STy->getElementType(0)->isIntegerTy(32)) return 0;
- const PointerType *PFTy = dyn_cast<PointerType>(STy->getElementType(1));
- if (!PFTy) return 0;
- const FunctionType *FTy = dyn_cast<FunctionType>(PFTy->getElementType());
- if (!FTy || !FTy->getReturnType()->isVoidTy() ||
- FTy->isVarArg() || FTy->getNumParams() != 0)
- return 0;
-
- // Verify that the initializer is simple enough for us to handle.
- if (!I->hasDefinitiveInitializer()) return 0;
- ConstantArray *CA = dyn_cast<ConstantArray>(I->getInitializer());
- if (!CA) return 0;
- for (User::op_iterator i = CA->op_begin(), e = CA->op_end(); i != e; ++i)
- if (ConstantStruct *CS = dyn_cast<ConstantStruct>(*i)) {
- if (isa<ConstantPointerNull>(CS->getOperand(1)))
- continue;
-
- // 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;
-}
+ GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
+ if (GV == 0) return 0;
+
+ // Verify that the initializer is simple enough for us to handle. We are
+ // only allowed to optimize the initializer if it is unique.
+ if (!GV->hasUniqueInitializer()) return 0;
-/// 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) {
+ if (isa<ConstantAggregateZero>(GV->getInitializer()))
+ return GV;
ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
- std::vector<Function*> Result;
- Result.reserve(CA->getNumOperands());
+
+ for (User::op_iterator i = CA->op_begin(), e = CA->op_end(); i != e; ++i) {
+ if (isa<ConstantAggregateZero>(*i))
+ continue;
+ ConstantStruct *CS = cast<ConstantStruct>(*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 = cast<ConstantInt>(CS->getOperand(0));
+ if (CI->getZExtValue() != 65535)
+ return 0;
+ }
+
+ return GV;
+}
+
+/// 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) {
+ if (GV->getInitializer()->isNullValue())
+ return std::vector<Function*>();
+ ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
+ std::vector<Function*> Result;
+ Result.reserve(CA->getNumOperands());
for (User::op_iterator i = CA->op_begin(), e = CA->op_end(); i != e; ++i) {
ConstantStruct *CS = cast<ConstantStruct>(*i);
Result.push_back(dyn_cast<Function>(CS->getOperand(1)));
/// InstallGlobalCtors - Given a specified llvm.global_ctors list, install the
/// specified array, returning the new global to use.
-static GlobalVariable *InstallGlobalCtors(GlobalVariable *GCL,
+static GlobalVariable *InstallGlobalCtors(GlobalVariable *GCL,
const std::vector<Function*> &Ctors) {
// If we made a change, reassemble the initializer list.
- std::vector<Constant*> CSVals;
- CSVals.push_back(ConstantInt::get(Type::getInt32Ty(GCL->getContext()),65535));
- CSVals.push_back(0);
-
+ Constant *CSVals[2];
+ CSVals[0] = ConstantInt::get(Type::getInt32Ty(GCL->getContext()), 65535);
+ CSVals[1] = 0;
+
+ StructType *StructTy =
+ cast <StructType>(
+ cast<ArrayType>(GCL->getType()->getElementType())->getElementType());
+
// 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::getVoidTy(GCL->getContext()),
+ Type *FTy = FunctionType::get(Type::getVoidTy(GCL->getContext()),
false);
- const PointerType *PFTy = PointerType::getUnqual(FTy);
+ PointerType *PFTy = PointerType::getUnqual(FTy);
CSVals[1] = Constant::getNullValue(PFTy);
CSVals[0] = ConstantInt::get(Type::getInt32Ty(GCL->getContext()),
- 2147483647);
+ 0x7fffffff);
}
- CAList.push_back(ConstantStruct::get(GCL->getContext(), CSVals, false));
+ CAList.push_back(ConstantStruct::get(StructTy, CSVals));
}
-
+
// Create the array initializer.
- const Type *StructTy =
- cast<ArrayType>(GCL->getType()->getElementType())->getElementType();
- Constant *CA = ConstantArray::get(ArrayType::get(StructTy,
+ Constant *CA = ConstantArray::get(ArrayType::get(StructTy,
CAList.size()), CAList);
-
+
// If we didn't change the number of elements, don't create a new GV.
if (CA->getType() == GCL->getInitializer()->getType()) {
GCL->setInitializer(CA);
return GCL;
}
-
+
// Create the new global and insert it next to the existing list.
GlobalVariable *NGV = new GlobalVariable(CA->getType(), GCL->isConstant(),
GCL->getLinkage(), CA, "",
GCL->isThreadLocal());
GCL->getParent()->getGlobalList().insert(GCL, NGV);
NGV->takeName(GCL);
-
+
// Nuke the old list, replacing any uses with the new one.
if (!GCL->use_empty()) {
Constant *V = NGV;
GCL->replaceAllUsesWith(V);
}
GCL->eraseFromParent();
-
+
if (Ctors.size())
return NGV;
else
}
-static Constant *getVal(DenseMap<Value*, Constant*> &ComputedValues,
- Value *V) {
- if (Constant *CV = dyn_cast<Constant>(V)) return CV;
- Constant *R = ComputedValues[V];
- assert(R && "Reference to an uncomputed value!");
- return R;
+static inline bool
+isSimpleEnoughValueToCommit(Constant *C,
+ SmallPtrSet<Constant*, 8> &SimpleConstants,
+ const TargetData *TD);
+
+
+/// isSimpleEnoughValueToCommit - Return true if the specified constant can be
+/// handled by the code generator. We don't want to generate something like:
+/// void *X = &X/42;
+/// because the code generator doesn't have a relocation that can handle that.
+///
+/// This function should be called if C was not found (but just got inserted)
+/// in SimpleConstants to avoid having to rescan the same constants all the
+/// time.
+static bool isSimpleEnoughValueToCommitHelper(Constant *C,
+ SmallPtrSet<Constant*, 8> &SimpleConstants,
+ const TargetData *TD) {
+ // Simple integer, undef, constant aggregate zero, global addresses, etc are
+ // all supported.
+ if (C->getNumOperands() == 0 || isa<BlockAddress>(C) ||
+ isa<GlobalValue>(C))
+ return true;
+
+ // Aggregate values are safe if all their elements are.
+ if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
+ isa<ConstantVector>(C)) {
+ for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i) {
+ Constant *Op = cast<Constant>(C->getOperand(i));
+ if (!isSimpleEnoughValueToCommit(Op, SimpleConstants, TD))
+ return false;
+ }
+ return true;
+ }
+
+ // We don't know exactly what relocations are allowed in constant expressions,
+ // so we allow &global+constantoffset, which is safe and uniformly supported
+ // across targets.
+ ConstantExpr *CE = cast<ConstantExpr>(C);
+ switch (CE->getOpcode()) {
+ case Instruction::BitCast:
+ // Bitcast is fine if the casted value is fine.
+ return isSimpleEnoughValueToCommit(CE->getOperand(0), SimpleConstants, TD);
+
+ case Instruction::IntToPtr:
+ case Instruction::PtrToInt:
+ // int <=> ptr is fine if the int type is the same size as the
+ // pointer type.
+ if (!TD || TD->getTypeSizeInBits(CE->getType()) !=
+ TD->getTypeSizeInBits(CE->getOperand(0)->getType()))
+ return false;
+ return isSimpleEnoughValueToCommit(CE->getOperand(0), SimpleConstants, TD);
+
+ // GEP is fine if it is simple + constant offset.
+ case Instruction::GetElementPtr:
+ for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
+ if (!isa<ConstantInt>(CE->getOperand(i)))
+ return false;
+ return isSimpleEnoughValueToCommit(CE->getOperand(0), SimpleConstants, TD);
+
+ case Instruction::Add:
+ // We allow simple+cst.
+ if (!isa<ConstantInt>(CE->getOperand(1)))
+ return false;
+ return isSimpleEnoughValueToCommit(CE->getOperand(0), SimpleConstants, TD);
+ }
+ return false;
+}
+
+static inline bool
+isSimpleEnoughValueToCommit(Constant *C,
+ SmallPtrSet<Constant*, 8> &SimpleConstants,
+ const TargetData *TD) {
+ // If we already checked this constant, we win.
+ if (!SimpleConstants.insert(C)) return true;
+ // Check the constant.
+ return isSimpleEnoughValueToCommitHelper(C, SimpleConstants, TD);
}
+
/// isSimpleEnoughPointerToCommit - Return true if this constant is simple
-/// enough for us to understand. In particular, if it is a cast of something,
-/// we punt. We basically just support direct accesses to globals and GEP's of
+/// enough for us to understand. In particular, if it is a cast to anything
+/// other than from one pointer type to another pointer type, we punt.
+/// We basically just support direct accesses to globals and GEP's of
/// globals. This should be kept up to date with CommitValueTo.
static bool isSimpleEnoughPointerToCommit(Constant *C) {
// Conservatively, avoid aggregate types. This is because we don't
return false;
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C))
- // Do not allow weak/linkonce/dllimport/dllexport linkage or
+ // Do not allow weak/*_odr/linkonce/dllimport/dllexport linkage or
// external globals.
- return GV->hasDefinitiveInitializer();
+ return GV->hasUniqueInitializer();
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
// Handle a constantexpr gep.
if (CE->getOpcode() == Instruction::GetElementPtr &&
isa<GlobalVariable>(CE->getOperand(0)) &&
cast<GEPOperator>(CE)->isInBounds()) {
GlobalVariable *GV = cast<GlobalVariable>(CE->getOperand(0));
- // Do not allow weak/linkonce/dllimport/dllexport linkage or
+ // Do not allow weak/*_odr/linkonce/dllimport/dllexport linkage or
// external globals.
- if (!GV->hasDefinitiveInitializer())
+ if (!GV->hasUniqueInitializer())
return false;
// The first index must be zero.
return false;
return ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE);
+
+ // A constantexpr bitcast from a pointer to another pointer is a no-op,
+ // and we know how to evaluate it by moving the bitcast from the pointer
+ // operand to the value operand.
+ } else if (CE->getOpcode() == Instruction::BitCast &&
+ isa<GlobalVariable>(CE->getOperand(0))) {
+ // Do not allow weak/*_odr/linkonce/dllimport/dllexport linkage or
+ // external globals.
+ return cast<GlobalVariable>(CE->getOperand(0))->hasUniqueInitializer();
}
+ }
+
return false;
}
assert(Val->getType() == Init->getType() && "Type mismatch!");
return Val;
}
-
- std::vector<Constant*> Elts;
- if (const StructType *STy = dyn_cast<StructType>(Init->getType())) {
+ SmallVector<Constant*, 32> Elts;
+ if (StructType *STy = dyn_cast<StructType>(Init->getType())) {
// Break up the constant into its elements.
- if (ConstantStruct *CS = dyn_cast<ConstantStruct>(Init)) {
- for (User::op_iterator i = CS->op_begin(), e = CS->op_end(); i != e; ++i)
- Elts.push_back(cast<Constant>(*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 {
- llvm_unreachable("This code is out of sync with "
- " ConstantFoldLoadThroughGEPConstantExpr");
- }
-
+ for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
+ Elts.push_back(Init->getAggregateElement(i));
+
// Replace the element that we are supposed to.
ConstantInt *CU = cast<ConstantInt>(Addr->getOperand(OpNo));
unsigned Idx = CU->getZExtValue();
assert(Idx < STy->getNumElements() && "Struct index out of range!");
Elts[Idx] = EvaluateStoreInto(Elts[Idx], Val, Addr, OpNo+1);
-
+
// Return the modified struct.
- return ConstantStruct::get(Init->getContext(), &Elts[0], Elts.size(),
- STy->isPacked());
- } else {
- ConstantInt *CI = cast<ConstantInt>(Addr->getOperand(OpNo));
- const SequentialType *InitTy = cast<SequentialType>(Init->getType());
+ return ConstantStruct::get(STy, Elts);
+ }
+
+ ConstantInt *CI = cast<ConstantInt>(Addr->getOperand(OpNo));
+ SequentialType *InitTy = cast<SequentialType>(Init->getType());
- uint64_t NumElts;
- if (const ArrayType *ATy = dyn_cast<ArrayType>(InitTy))
- NumElts = ATy->getNumElements();
- else
- NumElts = cast<VectorType>(InitTy)->getNumElements();
-
-
- // Break up the array into elements.
- if (ConstantArray *CA = dyn_cast<ConstantArray>(Init)) {
- for (User::op_iterator i = CA->op_begin(), e = CA->op_end(); i != e; ++i)
- Elts.push_back(cast<Constant>(*i));
- } else if (ConstantVector *CV = dyn_cast<ConstantVector>(Init)) {
- for (User::op_iterator i = CV->op_begin(), e = CV->op_end(); i != e; ++i)
- Elts.push_back(cast<Constant>(*i));
- } else if (isa<ConstantAggregateZero>(Init)) {
- Elts.assign(NumElts, Constant::getNullValue(InitTy->getElementType()));
- } else {
- assert(isa<UndefValue>(Init) && "This code is out of sync with "
- " ConstantFoldLoadThroughGEPConstantExpr");
- Elts.assign(NumElts, UndefValue::get(InitTy->getElementType()));
- }
-
- assert(CI->getZExtValue() < NumElts);
- Elts[CI->getZExtValue()] =
- EvaluateStoreInto(Elts[CI->getZExtValue()], Val, Addr, OpNo+1);
-
- if (Init->getType()->isArrayTy())
- return ConstantArray::get(cast<ArrayType>(InitTy), Elts);
- else
- return ConstantVector::get(&Elts[0], Elts.size());
- }
+ uint64_t NumElts;
+ if (ArrayType *ATy = dyn_cast<ArrayType>(InitTy))
+ NumElts = ATy->getNumElements();
+ else
+ NumElts = InitTy->getVectorNumElements();
+
+ // Break up the array into elements.
+ for (uint64_t i = 0, e = NumElts; i != e; ++i)
+ Elts.push_back(Init->getAggregateElement(i));
+
+ assert(CI->getZExtValue() < NumElts);
+ Elts[CI->getZExtValue()] =
+ EvaluateStoreInto(Elts[CI->getZExtValue()], Val, Addr, OpNo+1);
+
+ if (Init->getType()->isArrayTy())
+ return ConstantArray::get(cast<ArrayType>(InitTy), Elts);
+ return ConstantVector::get(Elts);
}
/// CommitValueTo - We have decided that Addr (which satisfies the predicate
GV->setInitializer(EvaluateStoreInto(GV->getInitializer(), Val, CE, 2));
}
+namespace {
+
+/// Evaluator - This class evaluates LLVM IR, producing the Constant
+/// representing each SSA instruction. Changes to global variables are stored
+/// in a mapping that can be iterated over after the evaluation is complete.
+/// Once an evaluation call fails, the evaluation object should not be reused.
+class Evaluator {
+public:
+ Evaluator(const TargetData *TD, const TargetLibraryInfo *TLI)
+ : TD(TD), TLI(TLI) {
+ ValueStack.push_back(new DenseMap<Value*, Constant*>);
+ }
+
+ ~Evaluator() {
+ DeleteContainerPointers(ValueStack);
+ 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;
+ }
+ }
+
+ /// 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.
+ bool EvaluateFunction(Function *F, Constant *&RetVal,
+ const SmallVectorImpl<Constant*> &ActualArgs);
+
+ /// EvaluateBlock - Evaluate all instructions in block BB, returning true if
+ /// successful, false if we can't evaluate it. NewBB returns the next BB that
+ /// control flows into, or null upon return.
+ bool EvaluateBlock(BasicBlock::iterator CurInst, BasicBlock *&NextBB);
+
+ Constant *getVal(Value *V) {
+ if (Constant *CV = dyn_cast<Constant>(V)) return CV;
+ Constant *R = ValueStack.back()->lookup(V);
+ assert(R && "Reference to an uncomputed value!");
+ return R;
+ }
+
+ void setVal(Value *V, Constant *C) {
+ ValueStack.back()->operator[](V) = C;
+ }
+
+ const DenseMap<Constant*, Constant*> &getMutatedMemory() const {
+ return MutatedMemory;
+ }
+
+ const SmallPtrSet<GlobalVariable*, 8> &getInvariants() const {
+ return Invariants;
+ }
+
+private:
+ Constant *ComputeLoadResult(Constant *P);
+
+ /// ValueStack - As we compute SSA register values, we store their contents
+ /// here. The back of the vector contains the current function and the stack
+ /// contains the values in the calling frames.
+ SmallVector<DenseMap<Value*, Constant*>*, 4> ValueStack;
+
+ /// CallStack - This is used to detect recursion. In pathological situations
+ /// we could hit exponential behavior, but at least there is nothing
+ /// unbounded.
+ SmallVector<Function*, 4> CallStack;
+
+ /// 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.
+ DenseMap<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.
+ SmallVector<GlobalVariable*, 32> AllocaTmps;
+
+ /// Invariants - These global variables have been marked invariant by the
+ /// static constructor.
+ SmallPtrSet<GlobalVariable*, 8> Invariants;
+
+ /// SimpleConstants - These are constants we have checked and know to be
+ /// simple enough to live in a static initializer of a global.
+ SmallPtrSet<Constant*, 8> SimpleConstants;
+
+ const TargetData *TD;
+ const TargetLibraryInfo *TLI;
+};
+
+} // anonymous namespace
+
/// 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 DenseMap<Constant*, Constant*> &Memory) {
+Constant *Evaluator::ComputeLoadResult(Constant *P) {
// If this memory location has been recently stored, use the stored value: it
// is the most up-to-date.
- DenseMap<Constant*, Constant*>::const_iterator I = Memory.find(P);
- if (I != Memory.end()) return I->second;
-
+ DenseMap<Constant*, Constant*>::const_iterator I = MutatedMemory.find(P);
+ if (I != MutatedMemory.end()) return I->second;
+
// Access it.
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(P)) {
if (GV->hasDefinitiveInitializer())
return GV->getInitializer();
return 0;
}
-
+
// Handle a constantexpr getelementptr.
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(P))
if (CE->getOpcode() == Instruction::GetElementPtr &&
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 SmallVectorImpl<Constant*> &ActualArgs,
- std::vector<Function*> &CallStack,
- DenseMap<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.
- DenseMap<Value*, Constant*> Values;
-
- // Initialize arguments to the incoming values specified.
- unsigned ArgNo = 0;
- for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); AI != E;
- ++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.
- SmallPtrSet<BasicBlock*, 32> ExecutedBlocks;
-
- // CurInst - The current instruction we're evaluating.
- BasicBlock::iterator CurInst = F->begin()->begin();
-
+/// EvaluateBlock - Evaluate all instructions in block BB, returning true if
+/// successful, false if we can't evaluate it. NewBB returns the next BB that
+/// control flows into, or null upon return.
+bool Evaluator::EvaluateBlock(BasicBlock::iterator CurInst,
+ BasicBlock *&NextBB) {
// 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 (!SI->isSimple()) return false; // no volatile/atomic accesses.
+ Constant *Ptr = getVal(SI->getOperand(1));
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
+ Ptr = ConstantFoldConstantExpression(CE, TD, TLI);
if (!isSimpleEnoughPointerToCommit(Ptr))
// If this is too complex for us to commit, reject it.
return false;
- Constant *Val = getVal(Values, SI->getOperand(0));
+
+ Constant *Val = getVal(SI->getOperand(0));
+
+ // If this might be too difficult for the backend to handle (e.g. the addr
+ // of one global variable divided by another) then we can't commit it.
+ if (!isSimpleEnoughValueToCommit(Val, SimpleConstants, TD))
+ return false;
+
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
+ if (CE->getOpcode() == Instruction::BitCast) {
+ // If we're evaluating a store through a bitcast, then we need
+ // to pull the bitcast off the pointer type and push it onto the
+ // stored value.
+ Ptr = CE->getOperand(0);
+
+ Type *NewTy = cast<PointerType>(Ptr->getType())->getElementType();
+
+ // In order to push the bitcast onto the stored value, a bitcast
+ // from NewTy to Val's type must be legal. If it's not, we can try
+ // introspecting NewTy to find a legal conversion.
+ while (!Val->getType()->canLosslesslyBitCastTo(NewTy)) {
+ // If NewTy is a struct, we can convert the pointer to the struct
+ // into a pointer to its first member.
+ // FIXME: This could be extended to support arrays as well.
+ if (StructType *STy = dyn_cast<StructType>(NewTy)) {
+ NewTy = STy->getTypeAtIndex(0U);
+
+ IntegerType *IdxTy = IntegerType::get(NewTy->getContext(), 32);
+ Constant *IdxZero = ConstantInt::get(IdxTy, 0, false);
+ Constant * const IdxList[] = {IdxZero, IdxZero};
+
+ Ptr = ConstantExpr::getGetElementPtr(Ptr, IdxList);
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
+ Ptr = ConstantFoldConstantExpression(CE, TD, TLI);
+
+ // If we can't improve the situation by introspecting NewTy,
+ // we have to give up.
+ } else {
+ return false;
+ }
+ }
+
+ // If we found compatible types, go ahead and push the bitcast
+ // onto the stored value.
+ Val = ConstantExpr::getBitCast(Val, NewTy);
+ }
+
MutatedMemory[Ptr] = Val;
} else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(CurInst)) {
InstResult = ConstantExpr::get(BO->getOpcode(),
- getVal(Values, BO->getOperand(0)),
- getVal(Values, BO->getOperand(1)));
+ getVal(BO->getOperand(0)),
+ getVal(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)));
+ getVal(CI->getOperand(0)),
+ getVal(CI->getOperand(1)));
} else if (CastInst *CI = dyn_cast<CastInst>(CurInst)) {
InstResult = ConstantExpr::getCast(CI->getOpcode(),
- getVal(Values, CI->getOperand(0)),
+ getVal(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)));
+ InstResult = ConstantExpr::getSelect(getVal(SI->getOperand(0)),
+ getVal(SI->getOperand(1)),
+ getVal(SI->getOperand(2)));
} else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(CurInst)) {
- Constant *P = getVal(Values, GEP->getOperand(0));
+ Constant *P = getVal(GEP->getOperand(0));
SmallVector<Constant*, 8> GEPOps;
for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end();
i != e; ++i)
- GEPOps.push_back(getVal(Values, *i));
- InstResult = cast<GEPOperator>(GEP)->isInBounds() ?
- ConstantExpr::getInBoundsGetElementPtr(P, &GEPOps[0], GEPOps.size()) :
- ConstantExpr::getGetElementPtr(P, &GEPOps[0], GEPOps.size());
+ GEPOps.push_back(getVal(*i));
+ InstResult =
+ ConstantExpr::getGetElementPtr(P, GEPOps,
+ cast<GEPOperator>(GEP)->isInBounds());
} 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 (!LI->isSimple()) return false; // no volatile/atomic accesses.
+ Constant *Ptr = getVal(LI->getOperand(0));
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
+ Ptr = ConstantFoldConstantExpression(CE, TD, TLI);
+ InstResult = ComputeLoadResult(Ptr);
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();
+ 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)) {
+ InstResult = AllocaTmps.back();
+ } else if (isa<CallInst>(CurInst) || isa<InvokeInst>(CurInst)) {
+ CallSite CS(CurInst);
// Debug info can safely be ignored here.
- if (isa<DbgInfoIntrinsic>(CI)) {
+ if (isa<DbgInfoIntrinsic>(CS.getInstruction())) {
++CurInst;
continue;
}
// Cannot handle inline asm.
- if (isa<InlineAsm>(CI->getCalledValue())) return false;
+ if (isa<InlineAsm>(CS.getCalledValue())) return false;
+
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CS.getInstruction())) {
+ if (MemSetInst *MSI = dyn_cast<MemSetInst>(II)) {
+ if (MSI->isVolatile()) return false;
+ Constant *Ptr = getVal(MSI->getDest());
+ Constant *Val = getVal(MSI->getValue());
+ Constant *DestVal = ComputeLoadResult(getVal(Ptr));
+ if (Val->isNullValue() && DestVal && DestVal->isNullValue()) {
+ // This memset is a no-op.
+ ++CurInst;
+ continue;
+ }
+ }
+
+ if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
+ II->getIntrinsicID() == Intrinsic::lifetime_end) {
+ ++CurInst;
+ continue;
+ }
+
+ if (II->getIntrinsicID() == Intrinsic::invariant_start) {
+ // We don't insert an entry into Values, as it doesn't have a
+ // meaningful return value.
+ if (!II->use_empty())
+ return false;
+ ConstantInt *Size = cast<ConstantInt>(II->getArgOperand(0));
+ Value *PtrArg = getVal(II->getArgOperand(1));
+ Value *Ptr = PtrArg->stripPointerCasts();
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Ptr)) {
+ Type *ElemTy = cast<PointerType>(GV->getType())->getElementType();
+ if (!Size->isAllOnesValue() &&
+ Size->getValue().getLimitedValue() >=
+ TD->getTypeStoreSize(ElemTy))
+ Invariants.insert(GV);
+ }
+ // Continue even if we do nothing.
+ ++CurInst;
+ continue;
+ }
+ return false;
+ }
// Resolve function pointers.
- Function *Callee = dyn_cast<Function>(getVal(Values,
- CI->getCalledValue()));
- if (!Callee) return false; // Cannot resolve.
+ Function *Callee = dyn_cast<Function>(getVal(CS.getCalledValue()));
+ if (!Callee || Callee->mayBeOverridden())
+ return false; // Cannot resolve.
SmallVector<Constant*, 8> Formals;
- CallSite CS(CI);
- for (User::op_iterator i = CS.arg_begin(), e = CS.arg_end();
- i != e; ++i)
- Formals.push_back(getVal(Values, *i));
+ for (User::op_iterator i = CS.arg_begin(), e = CS.arg_end(); i != e; ++i)
+ Formals.push_back(getVal(*i));
if (Callee->isDeclaration()) {
// If this is a function we can constant fold, do it.
- if (Constant *C = ConstantFoldCall(Callee, Formals.data(),
- Formals.size())) {
+ if (Constant *C = ConstantFoldCall(Callee, Formals, TLI)) {
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))
+ ValueStack.push_back(new DenseMap<Value*, Constant*>);
+ if (!EvaluateFunction(Callee, RetVal, Formals))
return false;
+ ValueStack.pop_back();
InstResult = RetVal;
+
+ if (InvokeInst *II = dyn_cast<InvokeInst>(CurInst)) {
+ NextBB = II->getNormalDest();
+ return true;
+ }
}
} else if (isa<TerminatorInst>(CurInst)) {
- BasicBlock *NewBB = 0;
if (BranchInst *BI = dyn_cast<BranchInst>(CurInst)) {
if (BI->isUnconditional()) {
- NewBB = BI->getSuccessor(0);
+ NextBB = BI->getSuccessor(0);
} else {
ConstantInt *Cond =
- dyn_cast<ConstantInt>(getVal(Values, BI->getCondition()));
+ dyn_cast<ConstantInt>(getVal(BI->getCondition()));
if (!Cond) return false; // Cannot determine.
- NewBB = BI->getSuccessor(!Cond->getZExtValue());
+ NextBB = BI->getSuccessor(!Cond->getZExtValue());
}
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(CurInst)) {
ConstantInt *Val =
- dyn_cast<ConstantInt>(getVal(Values, SI->getCondition()));
+ dyn_cast<ConstantInt>(getVal(SI->getCondition()));
if (!Val) return false; // Cannot determine.
- NewBB = SI->getSuccessor(SI->findCaseValue(Val));
+ unsigned ValTISucc = SI->resolveSuccessorIndex(SI->findCaseValue(Val));
+ NextBB = SI->getSuccessor(ValTISucc);
} else if (IndirectBrInst *IBI = dyn_cast<IndirectBrInst>(CurInst)) {
- Value *Val = getVal(Values, IBI->getAddress())->stripPointerCasts();
+ Value *Val = getVal(IBI->getAddress())->stripPointerCasts();
if (BlockAddress *BA = dyn_cast<BlockAddress>(Val))
- NewBB = BA->getBasicBlock();
+ NextBB = BA->getBasicBlock();
else
return false; // Cannot determine.
- } 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 if (isa<ReturnInst>(CurInst)) {
+ NextBB = 0;
} else {
- // invoke, unwind, unreachable.
+ // invoke, unwind, resume, unreachable.
return false; // Cannot handle this terminator.
}
-
- // Okay, we succeeded in evaluating this control flow. See if we have
- // executed the new block before. If so, we have a looping function,
- // which we cannot evaluate in reasonable time.
- if (!ExecutedBlocks.insert(NewBB))
- return false; // looped!
-
- // Okay, we have never been in this block before. Check to see if there
- // are any PHI nodes. If so, evaluate them with information about where
- // we came from.
- 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;
+
+ // We succeeded at evaluating this block!
+ return true;
} else {
// Did not know how to evaluate this!
return false;
}
-
- if (!CurInst->use_empty())
- Values[CurInst] = InstResult;
-
+
+ if (!CurInst->use_empty()) {
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(InstResult))
+ InstResult = ConstantFoldConstantExpression(CE, TD, TLI);
+
+ setVal(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.
- DenseMap<Constant*, Constant*> MutatedMemory;
+/// 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.
+bool Evaluator::EvaluateFunction(Function *F, Constant *&RetVal,
+ const SmallVectorImpl<Constant*> &ActualArgs) {
+ // 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;
- /// 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;
+ CallStack.push_back(F);
+ // 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)
+ setVal(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.
+ SmallPtrSet<BasicBlock*, 32> ExecutedBlocks;
+
+ // CurBB - The current basic block we're evaluating.
+ BasicBlock *CurBB = F->begin();
+
+ BasicBlock::iterator CurInst = CurBB->begin();
+
+ while (1) {
+ BasicBlock *NextBB = 0; // Initialized to avoid compiler warnings.
+ if (!EvaluateBlock(CurInst, NextBB))
+ return false;
+
+ if (NextBB == 0) {
+ // Successfully running until there's no next block means that we found
+ // the return. Fill it the return value and pop the call stack.
+ ReturnInst *RI = cast<ReturnInst>(CurBB->getTerminator());
+ if (RI->getNumOperands())
+ RetVal = getVal(RI->getOperand(0));
+ CallStack.pop_back();
+ return true;
+ }
+
+ // 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(NextBB))
+ 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.
+ PHINode *PN = 0;
+ for (CurInst = NextBB->begin();
+ (PN = dyn_cast<PHINode>(CurInst)); ++CurInst)
+ setVal(PN, getVal(PN->getIncomingValueForBlock(CurBB)));
+
+ // Advance to the next block.
+ CurBB = NextBB;
+ }
+}
+
+/// EvaluateStaticConstructor - Evaluate static constructors in the function, if
+/// we can. Return true if we can, false otherwise.
+static bool EvaluateStaticConstructor(Function *F, const TargetData *TD,
+ const TargetLibraryInfo *TLI) {
// Call the function.
+ Evaluator Eval(TD, TLI);
Constant *RetValDummy;
- bool EvalSuccess = EvaluateFunction(F, RetValDummy,
- SmallVector<Constant*, 0>(), CallStack,
- MutatedMemory, AllocaTmps);
+ bool EvalSuccess = Eval.EvaluateFunction(F, RetValDummy,
+ SmallVector<Constant*, 0>());
+
if (EvalSuccess) {
// We succeeded at evaluation: commit the result.
DEBUG(dbgs() << "FULLY EVALUATED GLOBAL CTOR FUNCTION '"
- << F->getName() << "' to " << MutatedMemory.size()
+ << F->getName() << "' to " << Eval.getMutatedMemory().size()
<< " stores.\n");
- for (DenseMap<Constant*, Constant*>::iterator I = MutatedMemory.begin(),
- E = MutatedMemory.end(); I != E; ++I)
+ for (DenseMap<Constant*, Constant*>::const_iterator I =
+ Eval.getMutatedMemory().begin(), E = Eval.getMutatedMemory().end();
+ I != E; ++I)
CommitValueTo(I->second, I->first);
+ for (SmallPtrSet<GlobalVariable*, 8>::const_iterator I =
+ Eval.getInvariants().begin(), E = Eval.getInvariants().end();
+ I != E; ++I)
+ (*I)->setConstant(true);
}
-
- // 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];
}
break;
}
-
+
// We cannot simplify external ctor functions.
if (F->empty()) continue;
-
+
// If we can evaluate the ctor at compile time, do.
- if (EvaluateStaticConstructor(F)) {
+ if (EvaluateStaticConstructor(F, TD, TLI)) {
Ctors.erase(Ctors.begin()+i);
MadeChange = true;
--i;
continue;
}
}
-
+
if (!MadeChange) return false;
-
+
GCL = InstallGlobalCtors(GCL, Ctors);
return true;
}
return Changed;
}
+static Function *FindCXAAtExit(Module &M, TargetLibraryInfo *TLI) {
+ if (!TLI->has(LibFunc::cxa_atexit))
+ return 0;
+
+ Function *Fn = M.getFunction(TLI->getName(LibFunc::cxa_atexit));
+
+ if (!Fn)
+ return 0;
+
+ FunctionType *FTy = Fn->getFunctionType();
+
+ // Checking that the function has the right return type, the right number of
+ // parameters and that they all have pointer types should be enough.
+ if (!FTy->getReturnType()->isIntegerTy() ||
+ FTy->getNumParams() != 3 ||
+ !FTy->getParamType(0)->isPointerTy() ||
+ !FTy->getParamType(1)->isPointerTy() ||
+ !FTy->getParamType(2)->isPointerTy())
+ return 0;
+
+ return Fn;
+}
+
+/// cxxDtorIsEmpty - Returns whether the given function is an empty C++
+/// destructor and can therefore be eliminated.
+/// Note that we assume that other optimization passes have already simplified
+/// the code so we only look for a function with a single basic block, where
+/// the only allowed instructions are 'ret', 'call' to an empty C++ dtor and
+/// other side-effect free instructions.
+static bool cxxDtorIsEmpty(const Function &Fn,
+ SmallPtrSet<const Function *, 8> &CalledFunctions) {
+ // FIXME: We could eliminate C++ destructors if they're readonly/readnone and
+ // nounwind, but that doesn't seem worth doing.
+ if (Fn.isDeclaration())
+ return false;
+
+ if (++Fn.begin() != Fn.end())
+ return false;
+
+ const BasicBlock &EntryBlock = Fn.getEntryBlock();
+ for (BasicBlock::const_iterator I = EntryBlock.begin(), E = EntryBlock.end();
+ I != E; ++I) {
+ if (const CallInst *CI = dyn_cast<CallInst>(I)) {
+ // Ignore debug intrinsics.
+ if (isa<DbgInfoIntrinsic>(CI))
+ continue;
+
+ const Function *CalledFn = CI->getCalledFunction();
+
+ if (!CalledFn)
+ return false;
+
+ SmallPtrSet<const Function *, 8> NewCalledFunctions(CalledFunctions);
+
+ // Don't treat recursive functions as empty.
+ if (!NewCalledFunctions.insert(CalledFn))
+ return false;
+
+ if (!cxxDtorIsEmpty(*CalledFn, NewCalledFunctions))
+ return false;
+ } else if (isa<ReturnInst>(*I))
+ return true; // We're done.
+ else if (I->mayHaveSideEffects())
+ return false; // Destructor with side effects, bail.
+ }
+
+ return false;
+}
+
+bool GlobalOpt::OptimizeEmptyGlobalCXXDtors(Function *CXAAtExitFn) {
+ /// Itanium C++ ABI p3.3.5:
+ ///
+ /// After constructing a global (or local static) object, that will require
+ /// destruction on exit, a termination function is registered as follows:
+ ///
+ /// extern "C" int __cxa_atexit ( void (*f)(void *), void *p, void *d );
+ ///
+ /// This registration, e.g. __cxa_atexit(f,p,d), is intended to cause the
+ /// call f(p) when DSO d is unloaded, before all such termination calls
+ /// registered before this one. It returns zero if registration is
+ /// successful, nonzero on failure.
+
+ // This pass will look for calls to __cxa_atexit where the function is trivial
+ // and remove them.
+ bool Changed = false;
+
+ for (Function::use_iterator I = CXAAtExitFn->use_begin(),
+ E = CXAAtExitFn->use_end(); I != E;) {
+ // We're only interested in calls. Theoretically, we could handle invoke
+ // instructions as well, but neither llvm-gcc nor clang generate invokes
+ // to __cxa_atexit.
+ CallInst *CI = dyn_cast<CallInst>(*I++);
+ if (!CI)
+ continue;
+
+ Function *DtorFn =
+ dyn_cast<Function>(CI->getArgOperand(0)->stripPointerCasts());
+ if (!DtorFn)
+ continue;
+
+ SmallPtrSet<const Function *, 8> CalledFunctions;
+ if (!cxxDtorIsEmpty(*DtorFn, CalledFunctions))
+ continue;
+
+ // Just remove the call.
+ CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
+ CI->eraseFromParent();
+
+ ++NumCXXDtorsRemoved;
+
+ Changed |= true;
+ }
+
+ return Changed;
+}
+
bool GlobalOpt::runOnModule(Module &M) {
bool Changed = false;
-
+
+ TD = getAnalysisIfAvailable<TargetData>();
+ TLI = &getAnalysis<TargetLibraryInfo>();
+
// Try to find the llvm.globalctors list.
GlobalVariable *GlobalCtors = FindGlobalCtors(M);
+ Function *CXAAtExitFn = FindCXAAtExit(M, TLI);
+
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);
// Resolve aliases, when possible.
LocalChange |= OptimizeGlobalAliases(M);
+
+ // Try to remove trivial global destructors.
+ if (CXAAtExitFn)
+ LocalChange |= OptimizeEmptyGlobalCXXDtors(CXAAtExitFn);
+
Changed |= LocalChange;
}
-
+
// TODO: Move all global ctors functions to the end of the module for code
// layout.
-
+
return Changed;
}
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