#include "llvm/Instructions.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/ConstantFolding.h"
-#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Target/TargetData.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/PointerIntPair.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"
/// markConstant - Return true if this is a change in status.
bool markConstant(Constant *V) {
- if (isConstant()) {
+ if (getLatticeValue() == constant) { // Constant but not forcedconstant.
assert(getConstant() == V && "Marking constant with different value");
return false;
}
/// Constant Propagation.
///
class SCCPSolver : public InstVisitor<SCCPSolver> {
- DenseSet<BasicBlock*> BBExecutable;// The basic blocks that are executable
- std::map<Value*, LatticeVal> ValueState; // The state each value is in.
+ const TargetData *TD;
+ SmallPtrSet<BasicBlock*, 8> BBExecutable;// The BBs that are executable.
+ DenseMap<Value*, LatticeVal> ValueState; // The state each value is in.
+ /// StructValueState - This maintains ValueState for values that have
+ /// StructType, for example for formal arguments, calls, insertelement, etc.
+ ///
+ DenseMap<std::pair<Value*, unsigned>, LatticeVal> StructValueState;
+
/// GlobalValue - If we are tracking any values for the contents of a global
/// variable, we keep a mapping from the constant accessor to the element of
/// the global, to the currently known value. If the value becomes
/// TrackedMultipleRetVals - Same as TrackedRetVals, but used for functions
/// that return multiple values.
DenseMap<std::pair<Function*, unsigned>, LatticeVal> TrackedMultipleRetVals;
-
+
+ /// MRVFunctionsTracked - Each function in TrackedMultipleRetVals is
+ /// represented here for efficient lookup.
+ SmallPtrSet<Function*, 16> MRVFunctionsTracked;
+
+ /// TrackingIncomingArguments - This is the set of functions for whose
+ /// arguments we make optimistic assumptions about and try to prove as
+ /// constants.
+ SmallPtrSet<Function*, 16> TrackingIncomingArguments;
+
/// The reason for two worklists is that overdefined is the lowest state
/// on the lattice, and moving things to overdefined as fast as possible
/// makes SCCP converge much faster.
typedef std::pair<BasicBlock*, BasicBlock*> Edge;
DenseSet<Edge> KnownFeasibleEdges;
public:
+ SCCPSolver(const TargetData *td) : TD(td) {}
/// MarkBlockExecutable - This method can be used by clients to mark all of
/// the blocks that are known to be intrinsically live in the processed unit.
- void MarkBlockExecutable(BasicBlock *BB) {
+ ///
+ /// This returns true if the block was not considered live before.
+ bool MarkBlockExecutable(BasicBlock *BB) {
+ if (!BBExecutable.insert(BB)) return false;
DEBUG(errs() << "Marking Block Executable: " << BB->getName() << "\n");
- BBExecutable.insert(BB); // Basic block is executable!
BBWorkList.push_back(BB); // Add the block to the work list!
+ return true;
}
/// TrackValueOfGlobalVariable - Clients can use this method to
/// specified global variable if it can. This is only legal to call if
/// performing Interprocedural SCCP.
void TrackValueOfGlobalVariable(GlobalVariable *GV) {
- const Type *ElTy = GV->getType()->getElementType();
- if (ElTy->isFirstClassType()) {
+ // We only track the contents of scalar globals.
+ if (GV->getType()->getElementType()->isSingleValueType()) {
LatticeVal &IV = TrackedGlobals[GV];
if (!isa<UndefValue>(GV->getInitializer()))
IV.markConstant(GV->getInitializer());
/// and out of the specified function (which cannot have its address taken),
/// this method must be called.
void AddTrackedFunction(Function *F) {
- assert(F->hasLocalLinkage() && "Can only track internal functions!");
// Add an entry, F -> undef.
if (const StructType *STy = dyn_cast<StructType>(F->getReturnType())) {
+ MRVFunctionsTracked.insert(F);
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
TrackedMultipleRetVals.insert(std::make_pair(std::make_pair(F, i),
LatticeVal()));
TrackedRetVals.insert(std::make_pair(F, LatticeVal()));
}
+ void AddArgumentTrackedFunction(Function *F) {
+ TrackingIncomingArguments.insert(F);
+ }
+
/// Solve - Solve for constants and executable blocks.
///
void Solve();
}
LatticeVal getLatticeValueFor(Value *V) const {
- std::map<Value*, LatticeVal>::const_iterator I = ValueState.find(V);
+ DenseMap<Value*, LatticeVal>::const_iterator I = ValueState.find(V);
assert(I != ValueState.end() && "V is not in valuemap!");
return I->second;
}
+
+ LatticeVal getStructLatticeValueFor(Value *V, unsigned i) const {
+ DenseMap<std::pair<Value*, unsigned>, LatticeVal>::const_iterator I =
+ StructValueState.find(std::make_pair(V, i));
+ assert(I != StructValueState.end() && "V is not in valuemap!");
+ return I->second;
+ }
/// getTrackedRetVals - Get the inferred return value map.
///
}
void markOverdefined(Value *V) {
+ assert(!isa<StructType>(V->getType()) && "Should use other method");
markOverdefined(ValueState[V], V);
}
+ /// markAnythingOverdefined - Mark the specified value overdefined. This
+ /// works with both scalars and structs.
+ void markAnythingOverdefined(Value *V) {
+ if (const StructType *STy = dyn_cast<StructType>(V->getType()))
+ for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
+ markOverdefined(getStructValueState(V, i), V);
+ else
+ markOverdefined(V);
+ }
+
private:
// markConstant - Make a value be marked as "constant". If the value
// is not already a constant, add it to the instruction work list so that
InstWorkList.push_back(V);
}
- void markForcedConstant(LatticeVal &IV, Value *V, Constant *C) {
- IV.markForcedConstant(C);
- DEBUG(errs() << "markForcedConstant: " << *C << ": " << *V << '\n');
- InstWorkList.push_back(V);
- }
-
void markConstant(Value *V, Constant *C) {
+ assert(!isa<StructType>(V->getType()) && "Should use other method");
markConstant(ValueState[V], V, C);
}
+ void markForcedConstant(Value *V, Constant *C) {
+ assert(!isa<StructType>(V->getType()) && "Should use other method");
+ ValueState[V].markForcedConstant(C);
+ DEBUG(errs() << "markForcedConstant: " << *C << ": " << *V << '\n');
+ InstWorkList.push_back(V);
+ }
+
+
// markOverdefined - Make a value be marked as "overdefined". If the
// value is not already overdefined, add it to the overdefined instruction
// work list so that the users of the instruction are updated later.
OverdefinedInstWorkList.push_back(V);
}
- void mergeInValue(LatticeVal &IV, Value *V, LatticeVal &MergeWithV) {
+ void mergeInValue(LatticeVal &IV, Value *V, LatticeVal MergeWithV) {
if (IV.isOverdefined() || MergeWithV.isUndefined())
return; // Noop.
if (MergeWithV.isOverdefined())
markOverdefined(IV, V);
}
- void mergeInValue(Value *V, LatticeVal &MergeWithV) {
+ void mergeInValue(Value *V, LatticeVal MergeWithV) {
+ assert(!isa<StructType>(V->getType()) && "Should use other method");
mergeInValue(ValueState[V], V, MergeWithV);
}
- // getValueState - Return the LatticeVal object that corresponds to the value.
- // This function is necessary because not all values should start out in the
- // underdefined state. Argument's should be overdefined, and
- // constants should be marked as constants. If a value is not known to be an
- // Instruction object, then use this accessor to get its value from the map.
- //
+ /// getValueState - Return the LatticeVal object that corresponds to the
+ /// value. This function handles the case when the value hasn't been seen yet
+ /// by properly seeding constants etc.
LatticeVal &getValueState(Value *V) {
- std::map<Value*, LatticeVal>::iterator I = ValueState.find(V);
- if (I != ValueState.end()) return I->second; // Common case, in the map
+ assert(!isa<StructType>(V->getType()) && "Should use getStructValueState");
+
+ std::pair<DenseMap<Value*, LatticeVal>::iterator, bool> I =
+ ValueState.insert(std::make_pair(V, LatticeVal()));
+ LatticeVal &LV = I.first->second;
- LatticeVal &LV = ValueState[V];
+ if (!I.second)
+ return LV; // Common case, already in the map.
if (Constant *C = dyn_cast<Constant>(V)) {
// Undef values remain undefined.
return LV;
}
- // markEdgeExecutable - Mark a basic block as executable, adding it to the BB
- // work list if it is not already executable.
- //
+ /// getStructValueState - Return the LatticeVal object that corresponds to the
+ /// value/field pair. This function handles the case when the value hasn't
+ /// been seen yet by properly seeding constants etc.
+ LatticeVal &getStructValueState(Value *V, unsigned i) {
+ assert(isa<StructType>(V->getType()) && "Should use getValueState");
+ assert(i < cast<StructType>(V->getType())->getNumElements() &&
+ "Invalid element #");
+
+ std::pair<DenseMap<std::pair<Value*, unsigned>, LatticeVal>::iterator,
+ bool> I = StructValueState.insert(
+ std::make_pair(std::make_pair(V, i), LatticeVal()));
+ LatticeVal &LV = I.first->second;
+
+ if (!I.second)
+ return LV; // Common case, already in the map.
+
+ if (Constant *C = dyn_cast<Constant>(V)) {
+ if (isa<UndefValue>(C))
+ ; // Undef values remain undefined.
+ else if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C))
+ LV.markConstant(CS->getOperand(i)); // Constants are constant.
+ else if (isa<ConstantAggregateZero>(C)) {
+ const Type *FieldTy = cast<StructType>(V->getType())->getElementType(i);
+ LV.markConstant(Constant::getNullValue(FieldTy));
+ } else
+ LV.markOverdefined(); // Unknown sort of constant.
+ }
+
+ // All others are underdefined by default.
+ return LV;
+ }
+
+
+ /// markEdgeExecutable - Mark a basic block as executable, adding it to the BB
+ /// work list if it is not already executable.
void markEdgeExecutable(BasicBlock *Source, BasicBlock *Dest) {
if (!KnownFeasibleEdges.insert(Edge(Source, Dest)).second)
return; // This edge is already known to be executable!
- if (BBExecutable.count(Dest)) {
- DEBUG(errs() << "Marking Edge Executable: " << Source->getName()
- << " -> " << Dest->getName() << "\n");
-
- // The destination is already executable, but we just made an edge
+ if (!MarkBlockExecutable(Dest)) {
+ // If the destination is already executable, we just made an *edge*
// feasible that wasn't before. Revisit the PHI nodes in the block
// because they have potentially new operands.
- for (BasicBlock::iterator I = Dest->begin(); isa<PHINode>(I); ++I)
- visitPHINode(*cast<PHINode>(I));
+ DEBUG(errs() << "Marking Edge Executable: " << Source->getName()
+ << " -> " << Dest->getName() << "\n");
- } else {
- MarkBlockExecutable(Dest);
+ PHINode *PN;
+ for (BasicBlock::iterator I = Dest->begin();
+ (PN = dyn_cast<PHINode>(I)); ++I)
+ visitPHINode(*PN);
}
}
// instruction that was just changed state somehow. Based on this
// information, we need to update the specified user of this instruction.
//
- void OperandChangedState(User *U) {
- // Only instructions use other variable values!
- Instruction &I = cast<Instruction>(*U);
- if (BBExecutable.count(I.getParent())) // Inst is executable?
- visit(I);
+ void OperandChangedState(Instruction *I) {
+ if (BBExecutable.count(I->getParent())) // Inst is executable?
+ visit(*I);
+ }
+
+ /// RemoveFromOverdefinedPHIs - If I has any entries in the
+ /// UsersOfOverdefinedPHIs map for PN, remove them now.
+ void RemoveFromOverdefinedPHIs(Instruction *I, PHINode *PN) {
+ if (UsersOfOverdefinedPHIs.empty()) return;
+ std::multimap<PHINode*, Instruction*>::iterator It, E;
+ tie(It, E) = UsersOfOverdefinedPHIs.equal_range(PN);
+ while (It != E) {
+ if (It->second == I)
+ UsersOfOverdefinedPHIs.erase(It++);
+ else
+ ++It;
+ }
}
private:
void visitInsertValueInst(InsertValueInst &IVI);
// Instructions that cannot be folded away.
- void visitStoreInst (Instruction &I);
+ void visitStoreInst (StoreInst &I);
void visitLoadInst (LoadInst &I);
void visitGetElementPtrInst(GetElementPtrInst &I);
void visitCallInst (CallInst &I) {
- if (isFreeCall(&I))
- return;
visitCallSite(CallSite::get(&I));
}
void visitInvokeInst (InvokeInst &II) {
void visitUnreachableInst(TerminatorInst &I) { /*returns void*/ }
void visitAllocaInst (Instruction &I) { markOverdefined(&I); }
void visitVANextInst (Instruction &I) { markOverdefined(&I); }
- void visitVAArgInst (Instruction &I) { markOverdefined(&I); }
+ void visitVAArgInst (Instruction &I) { markAnythingOverdefined(&I); }
void visitInstruction(Instruction &I) {
// If a new instruction is added to LLVM that we don't handle.
errs() << "SCCP: Don't know how to handle: " << I;
- markOverdefined(&I); // Just in case
+ markAnythingOverdefined(&I); // Just in case
}
};
return;
}
- LatticeVal &BCValue = getValueState(BI->getCondition());
+ LatticeVal BCValue = getValueState(BI->getCondition());
ConstantInt *CI = BCValue.getConstantInt();
if (CI == 0) {
// Overdefined condition variables, and branches on unfoldable constant
}
if (SwitchInst *SI = dyn_cast<SwitchInst>(&TI)) {
- LatticeVal &SCValue = getValueState(SI->getCondition());
+ LatticeVal SCValue = getValueState(SI->getCondition());
ConstantInt *CI = SCValue.getConstantInt();
if (CI == 0) { // Overdefined or undefined condition?
if (BI->isUnconditional())
return true;
- LatticeVal &BCValue = getValueState(BI->getCondition());
+ LatticeVal BCValue = getValueState(BI->getCondition());
// Overdefined condition variables mean the branch could go either way,
// undef conditions mean that neither edge is feasible yet.
return true;
if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
- LatticeVal &SCValue = getValueState(SI->getCondition());
+ LatticeVal SCValue = getValueState(SI->getCondition());
ConstantInt *CI = SCValue.getConstantInt();
if (CI == 0)
// successors executable.
//
void SCCPSolver::visitPHINode(PHINode &PN) {
- LatticeVal &PNIV = getValueState(&PN);
- if (PNIV.isOverdefined()) {
+ // If this PN returns a struct, just mark the result overdefined.
+ // TODO: We could do a lot better than this if code actually uses this.
+ if (isa<StructType>(PN.getType()))
+ return markAnythingOverdefined(&PN);
+
+ if (getValueState(&PN).isOverdefined()) {
// There may be instructions using this PHI node that are not overdefined
// themselves. If so, make sure that they know that the PHI node operand
// changed.
std::multimap<PHINode*, Instruction*>::iterator I, E;
tie(I, E) = UsersOfOverdefinedPHIs.equal_range(&PN);
- if (I != E) {
- SmallVector<Instruction*, 16> Users;
- for (; I != E; ++I) Users.push_back(I->second);
- while (!Users.empty()) {
- visit(Users.back());
- Users.pop_back();
- }
- }
+ if (I == E)
+ return;
+
+ SmallVector<Instruction*, 16> Users;
+ for (; I != E; ++I)
+ Users.push_back(I->second);
+ while (!Users.empty())
+ visit(Users.pop_back_val());
return; // Quick exit
}
// Super-extra-high-degree PHI nodes are unlikely to ever be marked constant,
// and slow us down a lot. Just mark them overdefined.
if (PN.getNumIncomingValues() > 64)
- return markOverdefined(PNIV, &PN);
-
+ return markOverdefined(&PN);
+
// Look at all of the executable operands of the PHI node. If any of them
// are overdefined, the PHI becomes overdefined as well. If they are all
// constant, and they agree with each other, the PHI becomes the identical
//
Constant *OperandVal = 0;
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
- LatticeVal &IV = getValueState(PN.getIncomingValue(i));
+ LatticeVal IV = getValueState(PN.getIncomingValue(i));
if (IV.isUndefined()) continue; // Doesn't influence PHI node.
if (!isEdgeFeasible(PN.getIncomingBlock(i), PN.getParent()))
markConstant(&PN, OperandVal); // Acquire operand value
}
+
+
+
void SCCPSolver::visitReturnInst(ReturnInst &I) {
- if (I.getNumOperands() == 0) return; // Ret void
+ if (I.getNumOperands() == 0) return; // ret void
Function *F = I.getParent()->getParent();
+ Value *ResultOp = I.getOperand(0);
+
// If we are tracking the return value of this function, merge it in.
- if (!F->hasLocalLinkage())
- return;
-
- if (!TrackedRetVals.empty() && I.getNumOperands() == 1) {
+ if (!TrackedRetVals.empty() && !isa<StructType>(ResultOp->getType())) {
DenseMap<Function*, LatticeVal>::iterator TFRVI =
TrackedRetVals.find(F);
- if (TFRVI != TrackedRetVals.end() &&
- !TFRVI->second.isOverdefined()) {
- LatticeVal &IV = getValueState(I.getOperand(0));
- mergeInValue(TFRVI->second, F, IV);
+ if (TFRVI != TrackedRetVals.end()) {
+ mergeInValue(TFRVI->second, F, getValueState(ResultOp));
return;
}
}
// Handle functions that return multiple values.
- if (!TrackedMultipleRetVals.empty() && I.getNumOperands() > 1) {
- for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i) {
- DenseMap<std::pair<Function*, unsigned>, LatticeVal>::iterator
- It = TrackedMultipleRetVals.find(std::make_pair(F, i));
- if (It == TrackedMultipleRetVals.end()) break;
- mergeInValue(It->second, F, getValueState(I.getOperand(i)));
- }
- } else if (!TrackedMultipleRetVals.empty() &&
- I.getNumOperands() == 1 &&
- isa<StructType>(I.getOperand(0)->getType())) {
- for (unsigned i = 0, e = I.getOperand(0)->getType()->getNumContainedTypes();
- i != e; ++i) {
- DenseMap<std::pair<Function*, unsigned>, LatticeVal>::iterator
- It = TrackedMultipleRetVals.find(std::make_pair(F, i));
- if (It == TrackedMultipleRetVals.end()) break;
- if (Value *Val = FindInsertedValue(I.getOperand(0), i, I.getContext()))
- mergeInValue(It->second, F, getValueState(Val));
- }
+ if (!TrackedMultipleRetVals.empty()) {
+ if (const StructType *STy = dyn_cast<StructType>(ResultOp->getType()))
+ if (MRVFunctionsTracked.count(F))
+ for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
+ mergeInValue(TrackedMultipleRetVals[std::make_pair(F, i)], F,
+ getStructValueState(ResultOp, i));
+
}
}
}
void SCCPSolver::visitCastInst(CastInst &I) {
- Value *V = I.getOperand(0);
- LatticeVal &VState = getValueState(V);
- if (VState.isOverdefined()) // Inherit overdefinedness of operand
+ LatticeVal OpSt = getValueState(I.getOperand(0));
+ if (OpSt.isOverdefined()) // Inherit overdefinedness of operand
markOverdefined(&I);
- else if (VState.isConstant()) // Propagate constant value
+ else if (OpSt.isConstant()) // Propagate constant value
markConstant(&I, ConstantExpr::getCast(I.getOpcode(),
- VState.getConstant(), I.getType()));
+ OpSt.getConstant(), I.getType()));
}
-void SCCPSolver::visitExtractValueInst(ExtractValueInst &EVI) {
- Value *Aggr = EVI.getAggregateOperand();
- // If the operand to the extractvalue is an undef, the result is undef.
- if (isa<UndefValue>(Aggr))
- return;
-
- // Currently only handle single-index extractvalues.
+void SCCPSolver::visitExtractValueInst(ExtractValueInst &EVI) {
+ // If this returns a struct, mark all elements over defined, we don't track
+ // structs in structs.
+ if (isa<StructType>(EVI.getType()))
+ return markAnythingOverdefined(&EVI);
+
+ // If this is extracting from more than one level of struct, we don't know.
if (EVI.getNumIndices() != 1)
return markOverdefined(&EVI);
-
- Function *F = 0;
- if (CallInst *CI = dyn_cast<CallInst>(Aggr))
- F = CI->getCalledFunction();
- else if (InvokeInst *II = dyn_cast<InvokeInst>(Aggr))
- F = II->getCalledFunction();
-
- // TODO: If IPSCCP resolves the callee of this function, we could propagate a
- // result back!
- if (F == 0 || TrackedMultipleRetVals.empty())
- return markOverdefined(&EVI);
-
- // See if we are tracking the result of the callee. If not tracking this
- // function (for example, it is a declaration) just move to overdefined.
- if (!TrackedMultipleRetVals.count(std::make_pair(F, *EVI.idx_begin())))
+
+ Value *AggVal = EVI.getAggregateOperand();
+ if (isa<StructType>(AggVal->getType())) {
+ unsigned i = *EVI.idx_begin();
+ LatticeVal EltVal = getStructValueState(AggVal, i);
+ mergeInValue(getValueState(&EVI), &EVI, EltVal);
+ } else {
+ // Otherwise, must be extracting from an array.
return markOverdefined(&EVI);
-
- // Otherwise, the value will be merged in here as a result of CallSite
- // handling.
+ }
}
void SCCPSolver::visitInsertValueInst(InsertValueInst &IVI) {
- Value *Aggr = IVI.getAggregateOperand();
- Value *Val = IVI.getInsertedValueOperand();
-
- // If the operands to the insertvalue are undef, the result is undef.
- if (isa<UndefValue>(Aggr) && isa<UndefValue>(Val))
- return;
-
- // Currently only handle single-index insertvalues.
- if (IVI.getNumIndices() != 1)
+ const StructType *STy = dyn_cast<StructType>(IVI.getType());
+ if (STy == 0)
return markOverdefined(&IVI);
-
- // Currently only handle insertvalue instructions that are in a single-use
- // chain that builds up a return value.
- for (const InsertValueInst *TmpIVI = &IVI; ; ) {
- if (!TmpIVI->hasOneUse())
- return markOverdefined(&IVI);
-
- const Value *V = *TmpIVI->use_begin();
- if (isa<ReturnInst>(V))
- break;
- TmpIVI = dyn_cast<InsertValueInst>(V);
- if (!TmpIVI)
- return markOverdefined(&IVI);
- }
- // See if we are tracking the result of the callee.
- Function *F = IVI.getParent()->getParent();
- DenseMap<std::pair<Function*, unsigned>, LatticeVal>::iterator
- It = TrackedMultipleRetVals.find(std::make_pair(F, *IVI.idx_begin()));
-
- // Merge in the inserted member value.
- if (It != TrackedMultipleRetVals.end())
- mergeInValue(It->second, F, getValueState(Val));
-
- // Mark the aggregate result of the IVI overdefined; any tracking that we do
- // will be done on the individual member values.
- markOverdefined(&IVI);
+ // If this has more than one index, we can't handle it, drive all results to
+ // undef.
+ if (IVI.getNumIndices() != 1)
+ return markAnythingOverdefined(&IVI);
+
+ Value *Aggr = IVI.getAggregateOperand();
+ unsigned Idx = *IVI.idx_begin();
+
+ // Compute the result based on what we're inserting.
+ for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
+ // This passes through all values that aren't the inserted element.
+ if (i != Idx) {
+ LatticeVal EltVal = getStructValueState(Aggr, i);
+ mergeInValue(getStructValueState(&IVI, i), &IVI, EltVal);
+ continue;
+ }
+
+ Value *Val = IVI.getInsertedValueOperand();
+ if (isa<StructType>(Val->getType()))
+ // We don't track structs in structs.
+ markOverdefined(getStructValueState(&IVI, i), &IVI);
+ else {
+ LatticeVal InVal = getValueState(Val);
+ mergeInValue(getStructValueState(&IVI, i), &IVI, InVal);
+ }
+ }
}
void SCCPSolver::visitSelectInst(SelectInst &I) {
- LatticeVal &CondValue = getValueState(I.getCondition());
+ // If this select returns a struct, just mark the result overdefined.
+ // TODO: We could do a lot better than this if code actually uses this.
+ if (isa<StructType>(I.getType()))
+ return markAnythingOverdefined(&I);
+
+ LatticeVal CondValue = getValueState(I.getCondition());
if (CondValue.isUndefined())
return;
if (ConstantInt *CondCB = CondValue.getConstantInt()) {
- mergeInValue(&I, getValueState(CondCB->getZExtValue() ? I.getTrueValue()
- : I.getFalseValue()));
+ Value *OpVal = CondCB->isZero() ? I.getFalseValue() : I.getTrueValue();
+ mergeInValue(&I, getValueState(OpVal));
return;
}
// Otherwise, the condition is overdefined or a constant we can't evaluate.
// See if we can produce something better than overdefined based on the T/F
// value.
- LatticeVal &TVal = getValueState(I.getTrueValue());
- LatticeVal &FVal = getValueState(I.getFalseValue());
+ LatticeVal TVal = getValueState(I.getTrueValue());
+ LatticeVal FVal = getValueState(I.getFalseValue());
// select ?, C, C -> C.
if (TVal.isConstant() && FVal.isConstant() &&
TVal.getConstant() == FVal.getConstant())
return markConstant(&I, FVal.getConstant());
- if (TVal.isUndefined()) { // select ?, undef, X -> X.
- mergeInValue(&I, FVal);
- } else if (FVal.isUndefined()) { // select ?, X, undef -> X.
- mergeInValue(&I, TVal);
- } else {
- markOverdefined(&I);
- }
+ if (TVal.isUndefined()) // select ?, undef, X -> X.
+ return mergeInValue(&I, FVal);
+ if (FVal.isUndefined()) // select ?, X, undef -> X.
+ return mergeInValue(&I, TVal);
+ markOverdefined(&I);
}
-// Handle BinaryOperators and Shift Instructions.
+// Handle Binary Operators.
void SCCPSolver::visitBinaryOperator(Instruction &I) {
+ LatticeVal V1State = getValueState(I.getOperand(0));
+ LatticeVal V2State = getValueState(I.getOperand(1));
+
LatticeVal &IV = ValueState[&I];
if (IV.isOverdefined()) return;
- LatticeVal &V1State = getValueState(I.getOperand(0));
- LatticeVal &V2State = getValueState(I.getOperand(1));
-
- if (V1State.isOverdefined() || V2State.isOverdefined()) {
- // If this is an AND or OR with 0 or -1, it doesn't matter that the other
- // operand is overdefined.
- if (I.getOpcode() == Instruction::And || I.getOpcode() == Instruction::Or) {
- LatticeVal *NonOverdefVal = 0;
- if (!V1State.isOverdefined()) {
- NonOverdefVal = &V1State;
- } else if (!V2State.isOverdefined()) {
- NonOverdefVal = &V2State;
+ if (V1State.isConstant() && V2State.isConstant())
+ return markConstant(IV, &I,
+ ConstantExpr::get(I.getOpcode(), V1State.getConstant(),
+ V2State.getConstant()));
+
+ // If something is undef, wait for it to resolve.
+ if (!V1State.isOverdefined() && !V2State.isOverdefined())
+ return;
+
+ // Otherwise, one of our operands is overdefined. Try to produce something
+ // better than overdefined with some tricks.
+
+ // If this is an AND or OR with 0 or -1, it doesn't matter that the other
+ // operand is overdefined.
+ if (I.getOpcode() == Instruction::And || I.getOpcode() == Instruction::Or) {
+ LatticeVal *NonOverdefVal = 0;
+ if (!V1State.isOverdefined())
+ NonOverdefVal = &V1State;
+ else if (!V2State.isOverdefined())
+ NonOverdefVal = &V2State;
+
+ if (NonOverdefVal) {
+ if (NonOverdefVal->isUndefined()) {
+ // Could annihilate value.
+ if (I.getOpcode() == Instruction::And)
+ markConstant(IV, &I, Constant::getNullValue(I.getType()));
+ else if (const VectorType *PT = dyn_cast<VectorType>(I.getType()))
+ markConstant(IV, &I, Constant::getAllOnesValue(PT));
+ else
+ markConstant(IV, &I,
+ Constant::getAllOnesValue(I.getType()));
+ return;
}
-
- if (NonOverdefVal) {
- if (NonOverdefVal->isUndefined()) {
- // Could annihilate value.
- if (I.getOpcode() == Instruction::And)
- markConstant(IV, &I, Constant::getNullValue(I.getType()));
- else if (const VectorType *PT = dyn_cast<VectorType>(I.getType()))
- markConstant(IV, &I, Constant::getAllOnesValue(PT));
- else
- markConstant(IV, &I,
- Constant::getAllOnesValue(I.getType()));
- return;
- } else {
- if (I.getOpcode() == Instruction::And) {
- // X and 0 = 0
- if (NonOverdefVal->getConstant()->isNullValue())
- return markConstant(IV, &I, NonOverdefVal->getConstant());
- } else {
- if (ConstantInt *CI = NonOverdefVal->getConstantInt())
- if (CI->isAllOnesValue()) // X or -1 = -1
- return markConstant(IV, &I, NonOverdefVal->getConstant());
- }
- }
+
+ if (I.getOpcode() == Instruction::And) {
+ // X and 0 = 0
+ if (NonOverdefVal->getConstant()->isNullValue())
+ return markConstant(IV, &I, NonOverdefVal->getConstant());
+ } else {
+ if (ConstantInt *CI = NonOverdefVal->getConstantInt())
+ if (CI->isAllOnesValue()) // X or -1 = -1
+ return markConstant(IV, &I, NonOverdefVal->getConstant());
}
}
+ }
- // If both operands are PHI nodes, it is possible that this instruction has
- // a constant value, despite the fact that the PHI node doesn't. Check for
- // this condition now.
- if (PHINode *PN1 = dyn_cast<PHINode>(I.getOperand(0)))
- if (PHINode *PN2 = dyn_cast<PHINode>(I.getOperand(1)))
- if (PN1->getParent() == PN2->getParent()) {
- // Since the two PHI nodes are in the same basic block, they must have
- // entries for the same predecessors. Walk the predecessor list, and
- // if all of the incoming values are constants, and the result of
- // evaluating this expression with all incoming value pairs is the
- // same, then this expression is a constant even though the PHI node
- // is not a constant!
- LatticeVal Result;
- for (unsigned i = 0, e = PN1->getNumIncomingValues(); i != e; ++i) {
- LatticeVal &In1 = getValueState(PN1->getIncomingValue(i));
- BasicBlock *InBlock = PN1->getIncomingBlock(i);
- LatticeVal &In2 =
- getValueState(PN2->getIncomingValueForBlock(InBlock));
-
- if (In1.isOverdefined() || In2.isOverdefined()) {
+ // If both operands are PHI nodes, it is possible that this instruction has
+ // a constant value, despite the fact that the PHI node doesn't. Check for
+ // this condition now.
+ if (PHINode *PN1 = dyn_cast<PHINode>(I.getOperand(0)))
+ if (PHINode *PN2 = dyn_cast<PHINode>(I.getOperand(1)))
+ if (PN1->getParent() == PN2->getParent()) {
+ // Since the two PHI nodes are in the same basic block, they must have
+ // entries for the same predecessors. Walk the predecessor list, and
+ // if all of the incoming values are constants, and the result of
+ // evaluating this expression with all incoming value pairs is the
+ // same, then this expression is a constant even though the PHI node
+ // is not a constant!
+ LatticeVal Result;
+ for (unsigned i = 0, e = PN1->getNumIncomingValues(); i != e; ++i) {
+ LatticeVal In1 = getValueState(PN1->getIncomingValue(i));
+ BasicBlock *InBlock = PN1->getIncomingBlock(i);
+ LatticeVal In2 =getValueState(PN2->getIncomingValueForBlock(InBlock));
+
+ if (In1.isOverdefined() || In2.isOverdefined()) {
+ Result.markOverdefined();
+ break; // Cannot fold this operation over the PHI nodes!
+ }
+
+ if (In1.isConstant() && In2.isConstant()) {
+ Constant *V = ConstantExpr::get(I.getOpcode(), In1.getConstant(),
+ In2.getConstant());
+ if (Result.isUndefined())
+ Result.markConstant(V);
+ else if (Result.isConstant() && Result.getConstant() != V) {
Result.markOverdefined();
- break; // Cannot fold this operation over the PHI nodes!
+ break;
}
-
- if (In1.isConstant() && In2.isConstant()) {
- Constant *V =
- ConstantExpr::get(I.getOpcode(), In1.getConstant(),
- In2.getConstant());
- if (Result.isUndefined())
- Result.markConstant(V);
- else if (Result.isConstant() && Result.getConstant() != V) {
- Result.markOverdefined();
- break;
- }
- }
- }
-
- // If we found a constant value here, then we know the instruction is
- // constant despite the fact that the PHI nodes are overdefined.
- if (Result.isConstant()) {
- markConstant(IV, &I, Result.getConstant());
- // Remember that this instruction is virtually using the PHI node
- // operands.
- UsersOfOverdefinedPHIs.insert(std::make_pair(PN1, &I));
- UsersOfOverdefinedPHIs.insert(std::make_pair(PN2, &I));
- return;
- } else if (Result.isUndefined()) {
- return;
}
+ }
- // Okay, this really is overdefined now. Since we might have
- // speculatively thought that this was not overdefined before, and
- // added ourselves to the UsersOfOverdefinedPHIs list for the PHIs,
- // make sure to clean out any entries that we put there, for
- // efficiency.
- std::multimap<PHINode*, Instruction*>::iterator It, E;
- tie(It, E) = UsersOfOverdefinedPHIs.equal_range(PN1);
- while (It != E) {
- if (It->second == &I) {
- UsersOfOverdefinedPHIs.erase(It++);
- } else
- ++It;
- }
- tie(It, E) = UsersOfOverdefinedPHIs.equal_range(PN2);
- while (It != E) {
- if (It->second == &I) {
- UsersOfOverdefinedPHIs.erase(It++);
- } else
- ++It;
- }
+ // If we found a constant value here, then we know the instruction is
+ // constant despite the fact that the PHI nodes are overdefined.
+ if (Result.isConstant()) {
+ markConstant(IV, &I, Result.getConstant());
+ // Remember that this instruction is virtually using the PHI node
+ // operands.
+ UsersOfOverdefinedPHIs.insert(std::make_pair(PN1, &I));
+ UsersOfOverdefinedPHIs.insert(std::make_pair(PN2, &I));
+ return;
}
+
+ if (Result.isUndefined())
+ return;
- markOverdefined(IV, &I);
- } else if (V1State.isConstant() && V2State.isConstant()) {
- markConstant(IV, &I,
- ConstantExpr::get(I.getOpcode(), V1State.getConstant(),
- V2State.getConstant()));
- }
+ // Okay, this really is overdefined now. Since we might have
+ // speculatively thought that this was not overdefined before, and
+ // added ourselves to the UsersOfOverdefinedPHIs list for the PHIs,
+ // make sure to clean out any entries that we put there, for
+ // efficiency.
+ RemoveFromOverdefinedPHIs(&I, PN1);
+ RemoveFromOverdefinedPHIs(&I, PN2);
+ }
+
+ markOverdefined(&I);
}
// Handle ICmpInst instruction.
void SCCPSolver::visitCmpInst(CmpInst &I) {
+ LatticeVal V1State = getValueState(I.getOperand(0));
+ LatticeVal V2State = getValueState(I.getOperand(1));
+
LatticeVal &IV = ValueState[&I];
if (IV.isOverdefined()) return;
- LatticeVal &V1State = getValueState(I.getOperand(0));
- LatticeVal &V2State = getValueState(I.getOperand(1));
-
- if (V1State.isOverdefined() || V2State.isOverdefined()) {
- // If both operands are PHI nodes, it is possible that this instruction has
- // a constant value, despite the fact that the PHI node doesn't. Check for
- // this condition now.
- if (PHINode *PN1 = dyn_cast<PHINode>(I.getOperand(0)))
- if (PHINode *PN2 = dyn_cast<PHINode>(I.getOperand(1)))
- if (PN1->getParent() == PN2->getParent()) {
- // Since the two PHI nodes are in the same basic block, they must have
- // entries for the same predecessors. Walk the predecessor list, and
- // if all of the incoming values are constants, and the result of
- // evaluating this expression with all incoming value pairs is the
- // same, then this expression is a constant even though the PHI node
- // is not a constant!
- LatticeVal Result;
- for (unsigned i = 0, e = PN1->getNumIncomingValues(); i != e; ++i) {
- LatticeVal &In1 = getValueState(PN1->getIncomingValue(i));
- BasicBlock *InBlock = PN1->getIncomingBlock(i);
- LatticeVal &In2 =
- getValueState(PN2->getIncomingValueForBlock(InBlock));
-
- if (In1.isOverdefined() || In2.isOverdefined()) {
+ if (V1State.isConstant() && V2State.isConstant())
+ return markConstant(IV, &I, ConstantExpr::getCompare(I.getPredicate(),
+ V1State.getConstant(),
+ V2State.getConstant()));
+
+ // If operands are still undefined, wait for it to resolve.
+ if (!V1State.isOverdefined() && !V2State.isOverdefined())
+ return;
+
+ // If something is overdefined, use some tricks to avoid ending up and over
+ // defined if we can.
+
+ // If both operands are PHI nodes, it is possible that this instruction has
+ // a constant value, despite the fact that the PHI node doesn't. Check for
+ // this condition now.
+ if (PHINode *PN1 = dyn_cast<PHINode>(I.getOperand(0)))
+ if (PHINode *PN2 = dyn_cast<PHINode>(I.getOperand(1)))
+ if (PN1->getParent() == PN2->getParent()) {
+ // Since the two PHI nodes are in the same basic block, they must have
+ // entries for the same predecessors. Walk the predecessor list, and
+ // if all of the incoming values are constants, and the result of
+ // evaluating this expression with all incoming value pairs is the
+ // same, then this expression is a constant even though the PHI node
+ // is not a constant!
+ LatticeVal Result;
+ for (unsigned i = 0, e = PN1->getNumIncomingValues(); i != e; ++i) {
+ LatticeVal In1 = getValueState(PN1->getIncomingValue(i));
+ BasicBlock *InBlock = PN1->getIncomingBlock(i);
+ LatticeVal In2 =getValueState(PN2->getIncomingValueForBlock(InBlock));
+
+ if (In1.isOverdefined() || In2.isOverdefined()) {
+ Result.markOverdefined();
+ break; // Cannot fold this operation over the PHI nodes!
+ }
+
+ if (In1.isConstant() && In2.isConstant()) {
+ Constant *V = ConstantExpr::getCompare(I.getPredicate(),
+ In1.getConstant(),
+ In2.getConstant());
+ if (Result.isUndefined())
+ Result.markConstant(V);
+ else if (Result.isConstant() && Result.getConstant() != V) {
Result.markOverdefined();
- break; // Cannot fold this operation over the PHI nodes!
- } else if (In1.isConstant() && In2.isConstant()) {
- Constant *V = ConstantExpr::getCompare(I.getPredicate(),
- In1.getConstant(),
- In2.getConstant());
- if (Result.isUndefined())
- Result.markConstant(V);
- else if (Result.isConstant() && Result.getConstant() != V) {
- Result.markOverdefined();
- break;
- }
+ break;
}
}
+ }
- // If we found a constant value here, then we know the instruction is
- // constant despite the fact that the PHI nodes are overdefined.
- if (Result.isConstant()) {
- markConstant(IV, &I, Result.getConstant());
- // Remember that this instruction is virtually using the PHI node
- // operands.
- UsersOfOverdefinedPHIs.insert(std::make_pair(PN1, &I));
- UsersOfOverdefinedPHIs.insert(std::make_pair(PN2, &I));
- return;
- } else if (Result.isUndefined()) {
- return;
- }
-
- // Okay, this really is overdefined now. Since we might have
- // speculatively thought that this was not overdefined before, and
- // added ourselves to the UsersOfOverdefinedPHIs list for the PHIs,
- // make sure to clean out any entries that we put there, for
- // efficiency.
- std::multimap<PHINode*, Instruction*>::iterator It, E;
- tie(It, E) = UsersOfOverdefinedPHIs.equal_range(PN1);
- while (It != E) {
- if (It->second == &I) {
- UsersOfOverdefinedPHIs.erase(It++);
- } else
- ++It;
- }
- tie(It, E) = UsersOfOverdefinedPHIs.equal_range(PN2);
- while (It != E) {
- if (It->second == &I) {
- UsersOfOverdefinedPHIs.erase(It++);
- } else
- ++It;
- }
+ // If we found a constant value here, then we know the instruction is
+ // constant despite the fact that the PHI nodes are overdefined.
+ if (Result.isConstant()) {
+ markConstant(&I, Result.getConstant());
+ // Remember that this instruction is virtually using the PHI node
+ // operands.
+ UsersOfOverdefinedPHIs.insert(std::make_pair(PN1, &I));
+ UsersOfOverdefinedPHIs.insert(std::make_pair(PN2, &I));
+ return;
}
+
+ if (Result.isUndefined())
+ return;
- markOverdefined(IV, &I);
- } else if (V1State.isConstant() && V2State.isConstant()) {
- markConstant(IV, &I, ConstantExpr::getCompare(I.getPredicate(),
- V1State.getConstant(),
- V2State.getConstant()));
- }
+ // Okay, this really is overdefined now. Since we might have
+ // speculatively thought that this was not overdefined before, and
+ // added ourselves to the UsersOfOverdefinedPHIs list for the PHIs,
+ // make sure to clean out any entries that we put there, for
+ // efficiency.
+ RemoveFromOverdefinedPHIs(&I, PN1);
+ RemoveFromOverdefinedPHIs(&I, PN2);
+ }
+
+ markOverdefined(&I);
}
void SCCPSolver::visitExtractElementInst(ExtractElementInst &I) {
- // FIXME : SCCP does not handle vectors properly.
+ // TODO : SCCP does not handle vectors properly.
return markOverdefined(&I);
#if 0
}
void SCCPSolver::visitInsertElementInst(InsertElementInst &I) {
- // FIXME : SCCP does not handle vectors properly.
+ // TODO : SCCP does not handle vectors properly.
return markOverdefined(&I);
#if 0
LatticeVal &ValState = getValueState(I.getOperand(0));
}
void SCCPSolver::visitShuffleVectorInst(ShuffleVectorInst &I) {
- // FIXME : SCCP does not handle vectors properly.
+ // TODO : SCCP does not handle vectors properly.
return markOverdefined(&I);
#if 0
LatticeVal &V1State = getValueState(I.getOperand(0));
// can turn this into a getelementptr ConstantExpr.
//
void SCCPSolver::visitGetElementPtrInst(GetElementPtrInst &I) {
- LatticeVal &IV = ValueState[&I];
- if (IV.isOverdefined()) return;
+ if (ValueState[&I].isOverdefined()) return;
SmallVector<Constant*, 8> Operands;
Operands.reserve(I.getNumOperands());
for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i) {
- LatticeVal &State = getValueState(I.getOperand(i));
+ LatticeVal State = getValueState(I.getOperand(i));
if (State.isUndefined())
return; // Operands are not resolved yet.
if (State.isOverdefined())
- return markOverdefined(IV, &I);
+ return markOverdefined(&I);
assert(State.isConstant() && "Unknown state!");
Operands.push_back(State.getConstant());
}
Constant *Ptr = Operands[0];
- Operands.erase(Operands.begin()); // Erase the pointer from idx list.
-
- markConstant(IV, &I, ConstantExpr::getGetElementPtr(Ptr, &Operands[0],
- Operands.size()));
+ markConstant(&I, ConstantExpr::getGetElementPtr(Ptr, &Operands[0]+1,
+ Operands.size()-1));
}
-void SCCPSolver::visitStoreInst(Instruction &SI) {
+void SCCPSolver::visitStoreInst(StoreInst &SI) {
+ // If this store is of a struct, ignore it.
+ if (isa<StructType>(SI.getOperand(0)->getType()))
+ return;
+
if (TrackedGlobals.empty() || !isa<GlobalVariable>(SI.getOperand(1)))
return;
+
GlobalVariable *GV = cast<GlobalVariable>(SI.getOperand(1));
DenseMap<GlobalVariable*, LatticeVal>::iterator I = TrackedGlobals.find(GV);
if (I == TrackedGlobals.end() || I->second.isOverdefined()) return;
- // Get the value we are storing into the global.
- LatticeVal &PtrVal = getValueState(SI.getOperand(0));
-
- mergeInValue(I->second, GV, PtrVal);
+ // Get the value we are storing into the global, then merge it.
+ mergeInValue(I->second, GV, getValueState(SI.getOperand(0)));
if (I->second.isOverdefined())
TrackedGlobals.erase(I); // No need to keep tracking this!
}
// Handle load instructions. If the operand is a constant pointer to a constant
// global, we can replace the load with the loaded constant value!
void SCCPSolver::visitLoadInst(LoadInst &I) {
+ // If this load is of a struct, just mark the result overdefined.
+ if (isa<StructType>(I.getType()))
+ return markAnythingOverdefined(&I);
+
+ LatticeVal PtrVal = getValueState(I.getOperand(0));
+ if (PtrVal.isUndefined()) return; // The pointer is not resolved yet!
+
LatticeVal &IV = ValueState[&I];
if (IV.isOverdefined()) return;
- LatticeVal &PtrVal = getValueState(I.getOperand(0));
- if (PtrVal.isUndefined()) return; // The pointer is not resolved yet!
- if (PtrVal.isConstant() && !I.isVolatile()) {
- Value *Ptr = PtrVal.getConstant();
- // TODO: Consider a target hook for valid address spaces for this xform.
- if (isa<ConstantPointerNull>(Ptr) && I.getPointerAddressSpace() == 0) {
- // load null -> null
- return markConstant(IV, &I, Constant::getNullValue(I.getType()));
- }
+ if (!PtrVal.isConstant() || I.isVolatile())
+ return markOverdefined(IV, &I);
+
+ Constant *Ptr = PtrVal.getConstant();
- // Transform load (constant global) into the value loaded.
- if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Ptr)) {
- if (GV->isConstant()) {
- if (GV->hasDefinitiveInitializer())
- return markConstant(IV, &I, GV->getInitializer());
-
- } else if (!TrackedGlobals.empty()) {
- // If we are tracking this global, merge in the known value for it.
- DenseMap<GlobalVariable*, LatticeVal>::iterator It =
- TrackedGlobals.find(GV);
- if (It != TrackedGlobals.end()) {
- mergeInValue(IV, &I, It->second);
- return;
- }
+ // load null -> null
+ if (isa<ConstantPointerNull>(Ptr) && I.getPointerAddressSpace() == 0)
+ return markConstant(IV, &I, Constant::getNullValue(I.getType()));
+
+ // Transform load (constant global) into the value loaded.
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Ptr)) {
+ if (!TrackedGlobals.empty()) {
+ // If we are tracking this global, merge in the known value for it.
+ DenseMap<GlobalVariable*, LatticeVal>::iterator It =
+ TrackedGlobals.find(GV);
+ if (It != TrackedGlobals.end()) {
+ mergeInValue(IV, &I, It->second);
+ return;
}
}
-
- // Transform load (constantexpr_GEP global, 0, ...) into the value loaded.
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
- if (CE->getOpcode() == Instruction::GetElementPtr)
- if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
- if (GV->isConstant() && GV->hasDefinitiveInitializer())
- if (Constant *V =
- ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
- return markConstant(IV, &I, V);
}
+ // Transform load from a constant into a constant if possible.
+ if (Constant *C = ConstantFoldLoadFromConstPtr(Ptr, TD))
+ return markConstant(IV, &I, C);
+
// Otherwise we cannot say for certain what value this load will produce.
// Bail out.
markOverdefined(IV, &I);
// The common case is that we aren't tracking the callee, either because we
// are not doing interprocedural analysis or the callee is indirect, or is
// external. Handle these cases first.
- if (F == 0 || !F->hasLocalLinkage()) {
+ if (F == 0 || F->isDeclaration()) {
CallOverdefined:
// Void return and not tracking callee, just bail.
if (I->getType()->isVoidTy()) return;
// Otherwise, if we have a single return value case, and if the function is
// a declaration, maybe we can constant fold it.
- if (!isa<StructType>(I->getType()) && F && F->isDeclaration() &&
+ if (F && F->isDeclaration() && !isa<StructType>(I->getType()) &&
canConstantFoldCallTo(F)) {
SmallVector<Constant*, 8> Operands;
for (CallSite::arg_iterator AI = CS.arg_begin(), E = CS.arg_end();
AI != E; ++AI) {
- LatticeVal &State = getValueState(*AI);
+ LatticeVal State = getValueState(*AI);
if (State.isUndefined())
return; // Operands are not resolved yet.
}
// Otherwise, we don't know anything about this call, mark it overdefined.
- return markOverdefined(I);
+ return markAnythingOverdefined(I);
}
- // If this is a single/zero retval case, see if we're tracking the function.
- DenseMap<Function*, LatticeVal>::iterator TFRVI = TrackedRetVals.find(F);
- if (TFRVI != TrackedRetVals.end()) {
- // If so, propagate the return value of the callee into this call result.
- mergeInValue(I, TFRVI->second);
- } else if (isa<StructType>(I->getType())) {
- // Check to see if we're tracking this callee, if not, handle it in the
- // common path above.
- DenseMap<std::pair<Function*, unsigned>, LatticeVal>::iterator
- TMRVI = TrackedMultipleRetVals.find(std::make_pair(F, 0));
- if (TMRVI == TrackedMultipleRetVals.end())
- goto CallOverdefined;
-
- // Need to mark as overdefined, otherwise it stays undefined which
- // creates extractvalue undef, <idx>
- markOverdefined(I);
+ // If this is a local function that doesn't have its address taken, mark its
+ // entry block executable and merge in the actual arguments to the call into
+ // the formal arguments of the function.
+ if (!TrackingIncomingArguments.empty() && TrackingIncomingArguments.count(F)){
+ MarkBlockExecutable(F->begin());
- // If we are tracking this callee, propagate the return values of the call
- // into this call site. We do this by walking all the uses. Single-index
- // ExtractValueInst uses can be tracked; anything more complicated is
- // currently handled conservatively.
- for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
- UI != E; ++UI) {
- if (ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(*UI)) {
- if (EVI->getNumIndices() == 1) {
- mergeInValue(EVI,
- TrackedMultipleRetVals[std::make_pair(F, *EVI->idx_begin())]);
- continue;
+ // Propagate information from this call site into the callee.
+ CallSite::arg_iterator CAI = CS.arg_begin();
+ for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
+ AI != E; ++AI, ++CAI) {
+ // If this argument is byval, and if the function is not readonly, there
+ // will be an implicit copy formed of the input aggregate.
+ if (AI->hasByValAttr() && !F->onlyReadsMemory()) {
+ markOverdefined(AI);
+ continue;
+ }
+
+ if (const StructType *STy = dyn_cast<StructType>(AI->getType())) {
+ for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
+ LatticeVal CallArg = getStructValueState(*CAI, i);
+ mergeInValue(getStructValueState(AI, i), AI, CallArg);
}
+ } else {
+ mergeInValue(AI, getValueState(*CAI));
}
- // The aggregate value is used in a way not handled here. Assume nothing.
- markOverdefined(*UI);
}
- } else {
- // Otherwise we're not tracking this callee, so handle it in the
- // common path above.
- goto CallOverdefined;
}
-
- // Finally, if this is the first call to the function hit, mark its entry
- // block executable.
- if (!BBExecutable.count(F->begin()))
- MarkBlockExecutable(F->begin());
- // Propagate information from this call site into the callee.
- CallSite::arg_iterator CAI = CS.arg_begin();
- for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
- AI != E; ++AI, ++CAI) {
- LatticeVal &IV = ValueState[AI];
- if (AI->hasByValAttr() && !F->onlyReadsMemory()) {
- IV.markOverdefined();
- continue;
- }
- if (!IV.isOverdefined())
- mergeInValue(IV, AI, getValueState(*CAI));
+ // If this is a single/zero retval case, see if we're tracking the function.
+ if (const StructType *STy = dyn_cast<StructType>(F->getReturnType())) {
+ if (!MRVFunctionsTracked.count(F))
+ goto CallOverdefined; // Not tracking this callee.
+
+ // If we are tracking this callee, propagate the result of the function
+ // into this call site.
+ for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
+ mergeInValue(getStructValueState(I, i), I,
+ TrackedMultipleRetVals[std::make_pair(F, i)]);
+ } else {
+ DenseMap<Function*, LatticeVal>::iterator TFRVI = TrackedRetVals.find(F);
+ if (TFRVI == TrackedRetVals.end())
+ goto CallOverdefined; // Not tracking this callee.
+
+ // If so, propagate the return value of the callee into this call result.
+ mergeInValue(I, TFRVI->second);
}
}
// Process the work lists until they are empty!
while (!BBWorkList.empty() || !InstWorkList.empty() ||
!OverdefinedInstWorkList.empty()) {
- // Process the instruction work list.
+ // Process the overdefined instruction's work list first, which drives other
+ // things to overdefined more quickly.
while (!OverdefinedInstWorkList.empty()) {
- Value *I = OverdefinedInstWorkList.back();
- OverdefinedInstWorkList.pop_back();
+ Value *I = OverdefinedInstWorkList.pop_back_val();
DEBUG(errs() << "\nPopped off OI-WL: " << *I << '\n');
//
for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
UI != E; ++UI)
- OperandChangedState(*UI);
+ if (Instruction *I = dyn_cast<Instruction>(*UI))
+ OperandChangedState(I);
}
// Process the instruction work list.
while (!InstWorkList.empty()) {
- Value *I = InstWorkList.back();
- InstWorkList.pop_back();
+ Value *I = InstWorkList.pop_back_val();
DEBUG(errs() << "\nPopped off I-WL: " << *I << '\n');
- // "I" got into the work list because it either made the transition from
- // bottom to constant
+ // "I" got into the work list because it made the transition from undef to
+ // constant.
//
// Anything on this worklist that is overdefined need not be visited
// since all of its users will have already been marked as overdefined.
// Update all of the users of this instruction's value.
//
- if (!getValueState(I).isOverdefined())
+ if (isa<StructType>(I->getType()) || !getValueState(I).isOverdefined())
for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
UI != E; ++UI)
- OperandChangedState(*UI);
+ if (Instruction *I = dyn_cast<Instruction>(*UI))
+ OperandChangedState(I);
}
// Process the basic block work list.
// Look for instructions which produce undef values.
if (I->getType()->isVoidTy()) continue;
+ if (const StructType *STy = dyn_cast<StructType>(I->getType())) {
+ // Only a few things that can be structs matter for undef. Just send
+ // all their results to overdefined. We could be more precise than this
+ // but it isn't worth bothering.
+ if (isa<CallInst>(I) || isa<SelectInst>(I)) {
+ for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
+ LatticeVal &LV = getStructValueState(I, i);
+ if (LV.isUndefined())
+ markOverdefined(LV, I);
+ }
+ }
+ continue;
+ }
+
LatticeVal &LV = getValueState(I);
if (!LV.isUndefined()) continue;
+ // No instructions using structs need disambiguation.
+ if (isa<StructType>(I->getOperand(0)->getType()))
+ continue;
+
// Get the lattice values of the first two operands for use below.
- LatticeVal &Op0LV = getValueState(I->getOperand(0));
+ LatticeVal Op0LV = getValueState(I->getOperand(0));
LatticeVal Op1LV;
if (I->getNumOperands() == 2) {
+ // No instructions using structs need disambiguation.
+ if (isa<StructType>(I->getOperand(1)->getType()))
+ continue;
+
// If this is a two-operand instruction, and if both operands are
// undefs, the result stays undef.
Op1LV = getValueState(I->getOperand(1));
// After a zero extend, we know the top part is zero. SExt doesn't have
// to be handled here, because we don't know whether the top part is 1's
// or 0's.
- assert(Op0LV.isUndefined());
- markForcedConstant(LV, I, Constant::getNullValue(ITy));
+ markForcedConstant(I, Constant::getNullValue(ITy));
return true;
case Instruction::Mul:
case Instruction::And:
// undef * X -> 0. X could be zero.
// undef & X -> 0. X could be zero.
- markForcedConstant(LV, I, Constant::getNullValue(ITy));
+ markForcedConstant(I, Constant::getNullValue(ITy));
return true;
case Instruction::Or:
// undef | X -> -1. X could be -1.
- if (const VectorType *PTy = dyn_cast<VectorType>(ITy))
- markForcedConstant(LV, I,
- Constant::getAllOnesValue(PTy));
- else
- markForcedConstant(LV, I, Constant::getAllOnesValue(ITy));
+ markForcedConstant(I, Constant::getAllOnesValue(ITy));
return true;
case Instruction::SDiv:
// undef / X -> 0. X could be maxint.
// undef % X -> 0. X could be 1.
- markForcedConstant(LV, I, Constant::getNullValue(ITy));
+ markForcedConstant(I, Constant::getNullValue(ITy));
return true;
case Instruction::AShr:
// X >>s undef -> X. X could be 0, X could have the high-bit known set.
if (Op0LV.isConstant())
- markForcedConstant(LV, I, Op0LV.getConstant());
+ markForcedConstant(I, Op0LV.getConstant());
else
- markOverdefined(LV, I);
+ markOverdefined(I);
return true;
case Instruction::LShr:
case Instruction::Shl:
// X >> undef -> 0. X could be 0.
// X << undef -> 0. X could be 0.
- markForcedConstant(LV, I, Constant::getNullValue(ITy));
+ markForcedConstant(I, Constant::getNullValue(ITy));
return true;
case Instruction::Select:
// undef ? X : Y -> X or Y. There could be commonality between X/Y.
}
if (Op1LV.isConstant())
- markForcedConstant(LV, I, Op1LV.getConstant());
+ markForcedConstant(I, Op1LV.getConstant());
else
- markOverdefined(LV, I);
+ markOverdefined(I);
return true;
case Instruction::Call:
// If a call has an undef result, it is because it is constant foldable
// but one of the inputs was undef. Just force the result to
// overdefined.
- markOverdefined(LV, I);
+ markOverdefined(I);
return true;
}
}
//
bool SCCP::runOnFunction(Function &F) {
DEBUG(errs() << "SCCP on function '" << F.getName() << "'\n");
- SCCPSolver Solver;
+ SCCPSolver Solver(getAnalysisIfAvailable<TargetData>());
// Mark the first block of the function as being executable.
Solver.MarkBlockExecutable(F.begin());
// Mark all arguments to the function as being overdefined.
for (Function::arg_iterator AI = F.arg_begin(), E = F.arg_end(); AI != E;++AI)
- Solver.markOverdefined(AI);
+ Solver.markAnythingOverdefined(AI);
// Solve for constants.
bool ResolvedUndefs = true;
if (Inst->getType()->isVoidTy() || isa<TerminatorInst>(Inst))
continue;
+ // TODO: Reconstruct structs from their elements.
+ if (isa<StructType>(Inst->getType()))
+ continue;
+
LatticeVal IV = Solver.getLatticeValueFor(Inst);
if (IV.isOverdefined())
continue;
}
bool IPSCCP::runOnModule(Module &M) {
- SCCPSolver Solver;
+ SCCPSolver Solver(getAnalysisIfAvailable<TargetData>());
// Loop over all functions, marking arguments to those with their addresses
// taken or that are external as overdefined.
//
- for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F)
- if (!F->hasLocalLinkage() || AddressIsTaken(F)) {
- if (!F->isDeclaration())
- Solver.MarkBlockExecutable(F->begin());
- for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
- AI != E; ++AI)
- Solver.markOverdefined(AI);
- } else {
+ for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
+ if (F->isDeclaration())
+ continue;
+
+ // If this is a strong or ODR definition of this function, then we can
+ // propagate information about its result into callsites of it.
+ if (!F->mayBeOverridden())
Solver.AddTrackedFunction(F);
+
+ // If this function only has direct calls that we can see, we can track its
+ // arguments and return value aggressively, and can assume it is not called
+ // unless we see evidence to the contrary.
+ if (F->hasLocalLinkage() && !AddressIsTaken(F)) {
+ Solver.AddArgumentTrackedFunction(F);
+ continue;
}
+ // Assume the function is called.
+ Solver.MarkBlockExecutable(F->begin());
+
+ // Assume nothing about the incoming arguments.
+ for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
+ AI != E; ++AI)
+ Solver.markAnythingOverdefined(AI);
+ }
+
// Loop over global variables. We inform the solver about any internal global
// variables that do not have their 'addresses taken'. If they don't have
// their addresses taken, we can propagate constants through them.
SmallVector<BasicBlock*, 512> BlocksToErase;
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
- for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
- AI != E; ++AI) {
- if (AI->use_empty()) continue;
-
- LatticeVal IV = Solver.getLatticeValueFor(AI);
- if (IV.isOverdefined()) continue;
-
- Constant *CST = IV.isConstant() ?
- IV.getConstant() : UndefValue::get(AI->getType());
- DEBUG(errs() << "*** Arg " << *AI << " = " << *CST <<"\n");
-
- // Replaces all of the uses of a variable with uses of the
- // constant.
- AI->replaceAllUsesWith(CST);
- ++IPNumArgsElimed;
+ if (Solver.isBlockExecutable(F->begin())) {
+ for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
+ AI != E; ++AI) {
+ if (AI->use_empty() || isa<StructType>(AI->getType())) continue;
+
+ // TODO: Could use getStructLatticeValueFor to find out if the entire
+ // result is a constant and replace it entirely if so.
+
+ LatticeVal IV = Solver.getLatticeValueFor(AI);
+ if (IV.isOverdefined()) continue;
+
+ Constant *CST = IV.isConstant() ?
+ IV.getConstant() : UndefValue::get(AI->getType());
+ DEBUG(errs() << "*** Arg " << *AI << " = " << *CST <<"\n");
+
+ // Replaces all of the uses of a variable with uses of the
+ // constant.
+ AI->replaceAllUsesWith(CST);
+ ++IPNumArgsElimed;
+ }
}
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
for (BasicBlock::iterator BI = BB->begin(), E = BB->end(); BI != E; ) {
Instruction *Inst = BI++;
- if (Inst->getType()->isVoidTy())
+ if (Inst->getType()->isVoidTy() || isa<StructType>(Inst->getType()))
continue;
+ // TODO: Could use getStructLatticeValueFor to find out if the entire
+ // result is a constant and replace it entirely if so.
+
LatticeVal IV = Solver.getLatticeValueFor(Inst);
if (IV.isOverdefined())
continue;
for (unsigned i = 0, e = BlocksToErase.size(); i != e; ++i) {
// If there are any PHI nodes in this successor, drop entries for BB now.
BasicBlock *DeadBB = BlocksToErase[i];
- while (!DeadBB->use_empty()) {
- Instruction *I = cast<Instruction>(DeadBB->use_back());
+ for (Value::use_iterator UI = DeadBB->use_begin(), UE = DeadBB->use_end();
+ UI != UE; ) {
+ // Grab the user and then increment the iterator early, as the user
+ // will be deleted. Step past all adjacent uses from the same user.
+ Instruction *I = dyn_cast<Instruction>(*UI);
+ do { ++UI; } while (UI != UE && *UI == I);
+
+ // Ignore blockaddress users; BasicBlock's dtor will handle them.
+ if (!I) continue;
+
bool Folded = ConstantFoldTerminator(I->getParent());
if (!Folded) {
// The constant folder may not have been able to fold the terminator
// TODO: Process multiple value ret instructions also.
const DenseMap<Function*, LatticeVal> &RV = Solver.getTrackedRetVals();
for (DenseMap<Function*, LatticeVal>::const_iterator I = RV.begin(),
- E = RV.end(); I != E; ++I)
- if (!I->second.isOverdefined() &&
- !I->first->getReturnType()->isVoidTy()) {
- Function *F = I->first;
- for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
- if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator()))
- if (!isa<UndefValue>(RI->getOperand(0)))
- RI->setOperand(0, UndefValue::get(F->getReturnType()));
- }
-
+ E = RV.end(); I != E; ++I) {
+ Function *F = I->first;
+ if (I->second.isOverdefined() || F->getReturnType()->isVoidTy())
+ continue;
+
+ // We can only do this if we know that nothing else can call the function.
+ if (!F->hasLocalLinkage() || AddressIsTaken(F))
+ continue;
+
+ for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
+ if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator()))
+ if (!isa<UndefValue>(RI->getOperand(0)))
+ RI->setOperand(0, UndefValue::get(F->getReturnType()));
+ }
+
// If we infered constant or undef values for globals variables, we can delete
// the global and any stores that remain to it.
const DenseMap<GlobalVariable*, LatticeVal> &TG = Solver.getTrackedGlobals();
projects / oota-llvm.git / blobdiff