#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"
/// 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;
}
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.
/// 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");
+ DEBUG(dbgs() << "Marking Block Executable: " << BB->getName() << "\n");
BBWorkList.push_back(BB); // Add the block to the work list!
return true;
}
/// 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();
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(!V->getType()->isStructTy() && "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
//
void markConstant(LatticeVal &IV, Value *V, Constant *C) {
if (!IV.markConstant(C)) return;
- DEBUG(errs() << "markConstant: " << *C << ": " << *V << '\n');
- InstWorkList.push_back(V);
+ DEBUG(dbgs() << "markConstant: " << *C << ": " << *V << '\n');
+ if (IV.isOverdefined())
+ OverdefinedInstWorkList.push_back(V);
+ else
+ InstWorkList.push_back(V);
}
void markConstant(Value *V, Constant *C) {
+ assert(!V->getType()->isStructTy() && "Should use other method");
markConstant(ValueState[V], V, C);
}
void markForcedConstant(Value *V, Constant *C) {
- ValueState[V].markForcedConstant(C);
- DEBUG(errs() << "markForcedConstant: " << *C << ": " << *V << '\n');
- InstWorkList.push_back(V);
+ assert(!V->getType()->isStructTy() && "Should use other method");
+ LatticeVal &IV = ValueState[V];
+ IV.markForcedConstant(C);
+ DEBUG(dbgs() << "markForcedConstant: " << *C << ": " << *V << '\n');
+ if (IV.isOverdefined())
+ OverdefinedInstWorkList.push_back(V);
+ else
+ InstWorkList.push_back(V);
}
void markOverdefined(LatticeVal &IV, Value *V) {
if (!IV.markOverdefined()) return;
- DEBUG(errs() << "markOverdefined: ";
+ DEBUG(dbgs() << "markOverdefined: ";
if (Function *F = dyn_cast<Function>(V))
- errs() << "Function '" << F->getName() << "'\n";
+ dbgs() << "Function '" << F->getName() << "'\n";
else
- errs() << *V << '\n');
+ dbgs() << *V << '\n');
// Only instructions go on the work list
OverdefinedInstWorkList.push_back(V);
}
}
void mergeInValue(Value *V, LatticeVal MergeWithV) {
+ assert(!V->getType()->isStructTy() && "Should use other method");
mergeInValue(ValueState[V], V, MergeWithV);
}
/// value. This function handles the case when the value hasn't been seen yet
/// by properly seeding constants etc.
LatticeVal &getValueState(Value *V) {
- DenseMap<Value*, LatticeVal>::iterator I = ValueState.find(V);
- if (I != ValueState.end()) return I->second; // Common case, in the map
+ assert(!V->getType()->isStructTy() && "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;
}
+ /// 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(V->getType()->isStructTy() && "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 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.
- DEBUG(errs() << "Marking Edge Executable: " << Source->getName()
+ DEBUG(dbgs() << "Marking Edge Executable: " << Source->getName()
<< " -> " << Dest->getName() << "\n");
PHINode *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
}
}
+ /// InsertInOverdefinedPHIs - Insert an entry in the UsersOfOverdefinedPHIS
+ /// map for I and PN, but if one is there already, do not create another.
+ /// (Duplicate entries do not break anything directly, but can lead to
+ /// exponential growth of the table in rare cases.)
+ void InsertInOverdefinedPHIs(Instruction *I, PHINode *PN) {
+ std::multimap<PHINode*, Instruction*>::iterator J, E;
+ bool found = false;
+ tie(J, E) = UsersOfOverdefinedPHIs.equal_range(PN);
+ for (; J != E; ++J)
+ if (J->second == I) {
+ found = true;
+ break;
+ }
+ if (!found)
+ UsersOfOverdefinedPHIs.insert(std::make_pair(PN, I));
+ }
+
private:
friend class InstVisitor<SCCPSolver>;
void visitLoadInst (LoadInst &I);
void visitGetElementPtrInst(GetElementPtrInst &I);
void visitCallInst (CallInst &I) {
- if (isFreeCall(&I))
- return;
- visitCallSite(CallSite::get(&I));
+ visitCallSite(&I);
}
void visitInvokeInst (InvokeInst &II) {
- visitCallSite(CallSite::get(&II));
+ visitCallSite(&II);
visitTerminatorInst(II);
}
void visitCallSite (CallSite CS);
void visitUnwindInst (TerminatorInst &I) { /*returns void*/ }
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
+ dbgs() << "SCCP: Don't know how to handle: " << I;
+ markAnythingOverdefined(&I); // Just in case
}
};
}
#ifndef NDEBUG
- errs() << "Unknown terminator instruction: " << TI << '\n';
+ dbgs() << "Unknown terminator instruction: " << TI << '\n';
#endif
llvm_unreachable("SCCP: Don't know how to handle this terminator!");
}
return true;
#ifndef NDEBUG
- errs() << "Unknown terminator instruction: " << *TI << '\n';
+ dbgs() << "Unknown terminator instruction: " << *TI << '\n';
#endif
llvm_unreachable(0);
}
// successors executable.
//
void SCCPSolver::visitPHINode(PHINode &PN) {
+ // 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 (PN.getType()->isStructTy())
+ 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
// and slow us down a lot. Just mark them overdefined.
if (PN.getNumIncomingValues() > 64)
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
markConstant(&PN, OperandVal); // Acquire operand value
}
+
+
+
void SCCPSolver::visitReturnInst(ReturnInst &I) {
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()) {
+ if (!TrackedRetVals.empty() && !ResultOp->getType()->isStructTy()) {
DenseMap<Function*, LatticeVal>::iterator TFRVI =
TrackedRetVals.find(F);
- if (TFRVI != TrackedRetVals.end() &&
- !TFRVI->second.isOverdefined()) {
- mergeInValue(TFRVI->second, F, getValueState(I.getOperand(0)));
+ if (TFRVI != TrackedRetVals.end()) {
+ mergeInValue(TFRVI->second, F, getValueState(ResultOp));
return;
}
}
// Handle functions that return multiple values.
- if (!TrackedMultipleRetVals.empty() &&
- 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));
+
}
}
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 (EVI.getType()->isStructTy())
+ 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 (AggVal->getType()->isStructTy()) {
+ 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 (Val->getType()->isStructTy())
+ // 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) {
+ // 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 (I.getType()->isStructTy())
+ return markAnythingOverdefined(&I);
+
LatticeVal CondValue = getValueState(I.getCondition());
if (CondValue.isUndefined())
return;
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));
+ // operands.
+ InsertInOverdefinedPHIs(&I, PN1);
+ InsertInOverdefinedPHIs(&I, PN2);
return;
}
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));
+ InsertInOverdefinedPHIs(&I, PN1);
+ InsertInOverdefinedPHIs(&I, PN2);
return;
}
}
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());
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());
}
void SCCPSolver::visitStoreInst(StoreInst &SI) {
+ // If this store is of a struct, ignore it.
+ if (SI.getOperand(0)->getType()->isStructTy())
+ return;
+
if (TrackedGlobals.empty() || !isa<GlobalVariable>(SI.getOperand(1)))
return;
// 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 (I.getType()->isStructTy())
+ return markAnythingOverdefined(&I);
+
LatticeVal PtrVal = getValueState(I.getOperand(0));
if (PtrVal.isUndefined()) return; // The pointer is not resolved yet!
// 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() && !I->getType()->isStructTy() &&
canConstantFoldCallTo(F)) {
SmallVector<Constant*, 8> Operands;
}
// 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.
- 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) {
- if (AI->hasByValAttr() && !F->onlyReadsMemory()) {
- markOverdefined(AI);
- continue;
- }
+ // 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.
- mergeInValue(AI, getValueState(*CAI));
+ // 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);
}
}
while (!OverdefinedInstWorkList.empty()) {
Value *I = OverdefinedInstWorkList.pop_back_val();
- DEBUG(errs() << "\nPopped off OI-WL: " << *I << '\n');
+ DEBUG(dbgs() << "\nPopped off OI-WL: " << *I << '\n');
// "I" got into the work list because it either made the transition from
// bottom to constant
//
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.pop_back_val();
- DEBUG(errs() << "\nPopped off I-WL: " << *I << '\n');
+ DEBUG(dbgs() << "\nPopped off I-WL: " << *I << '\n');
// "I" got into the work list because it made the transition from undef to
// constant.
// 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 (I->getType()->isStructTy() || !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.
BasicBlock *BB = BBWorkList.back();
BBWorkList.pop_back();
- DEBUG(errs() << "\nPopped off BBWL: " << *BB << '\n');
+ DEBUG(dbgs() << "\nPopped off BBWL: " << *BB << '\n');
// Notify all instructions in this basic block that they are newly
// executable.
// 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 (I->getOperand(0)->getType()->isStructTy())
+ continue;
+
// Get the lattice values of the first two operands for use below.
LatticeVal Op0LV = getValueState(I->getOperand(0));
LatticeVal Op1LV;
if (I->getNumOperands() == 2) {
+ // No instructions using structs need disambiguation.
+ if (I->getOperand(1)->getType()->isStructTy())
+ 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.
+ case Instruction::SIToFP: // some FP values are not possible, just use 0.
+ case Instruction::UIToFP: // some FP values are not possible, just use 0.
markForcedConstant(I, Constant::getNullValue(ITy));
return true;
case Instruction::Mul:
}
}
+ // Check to see if we have a branch or switch on an undefined value. If so
+ // we force the branch to go one way or the other to make the successor
+ // values live. It doesn't really matter which way we force it.
TerminatorInst *TI = BB->getTerminator();
if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
if (!BI->isConditional()) continue;
if (!getValueState(BI->getCondition()).isUndefined())
continue;
- } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
+
+ // If the input to SCCP is actually branch on undef, fix the undef to
+ // false.
+ if (isa<UndefValue>(BI->getCondition())) {
+ BI->setCondition(ConstantInt::getFalse(BI->getContext()));
+ markEdgeExecutable(BB, TI->getSuccessor(1));
+ return true;
+ }
+
+ // Otherwise, it is a branch on a symbolic value which is currently
+ // considered to be undef. Handle this by forcing the input value to the
+ // branch to false.
+ markForcedConstant(BI->getCondition(),
+ ConstantInt::getFalse(TI->getContext()));
+ return true;
+ }
+
+ if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
if (SI->getNumSuccessors() < 2) // no cases
continue;
if (!getValueState(SI->getCondition()).isUndefined())
continue;
- } else {
- continue;
- }
-
- // If the edge to the second successor isn't thought to be feasible yet,
- // mark it so now. We pick the second one so that this goes to some
- // enumerated value in a switch instead of going to the default destination.
- if (KnownFeasibleEdges.count(Edge(BB, TI->getSuccessor(1))))
- continue;
-
- // Otherwise, it isn't already thought to be feasible. Mark it as such now
- // and return. This will make other blocks reachable, which will allow new
- // values to be discovered and existing ones to be moved in the lattice.
- markEdgeExecutable(BB, TI->getSuccessor(1));
-
- // This must be a conditional branch of switch on undef. At this point,
- // force the old terminator to branch to the first successor. This is
- // required because we are now influencing the dataflow of the function with
- // the assumption that this edge is taken. If we leave the branch condition
- // as undef, then further analysis could think the undef went another way
- // leading to an inconsistent set of conclusions.
- if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
- BI->setCondition(ConstantInt::getFalse(BI->getContext()));
- } else {
- SwitchInst *SI = cast<SwitchInst>(TI);
- SI->setCondition(SI->getCaseValue(1));
+
+ // If the input to SCCP is actually switch on undef, fix the undef to
+ // the first constant.
+ if (isa<UndefValue>(SI->getCondition())) {
+ SI->setCondition(SI->getCaseValue(1));
+ markEdgeExecutable(BB, TI->getSuccessor(1));
+ return true;
+ }
+
+ markForcedConstant(SI->getCondition(), SI->getCaseValue(1));
+ return true;
}
-
- return true;
}
return false;
///
struct SCCP : public FunctionPass {
static char ID; // Pass identification, replacement for typeid
- SCCP() : FunctionPass(&ID) {}
+ SCCP() : FunctionPass(ID) {
+ initializeSCCPPass(*PassRegistry::getPassRegistry());
+ }
// runOnFunction - Run the Sparse Conditional Constant Propagation
// algorithm, and return true if the function was modified.
} // end anonymous namespace
char SCCP::ID = 0;
-static RegisterPass<SCCP>
-X("sccp", "Sparse Conditional Constant Propagation");
+INITIALIZE_PASS(SCCP, "sccp",
+ "Sparse Conditional Constant Propagation", false, false)
// createSCCPPass - This is the public interface to this file.
FunctionPass *llvm::createSCCPPass() {
}
static void DeleteInstructionInBlock(BasicBlock *BB) {
- DEBUG(errs() << " BasicBlock Dead:" << *BB);
+ DEBUG(dbgs() << " BasicBlock Dead:" << *BB);
++NumDeadBlocks;
// Delete the instructions backwards, as it has a reduced likelihood of
// and return true if the function was modified.
//
bool SCCP::runOnFunction(Function &F) {
- DEBUG(errs() << "SCCP on function '" << F.getName() << "'\n");
+ DEBUG(dbgs() << "SCCP on function '" << F.getName() << "'\n");
SCCPSolver Solver(getAnalysisIfAvailable<TargetData>());
// Mark the first block of the function as being executable.
// 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;
while (ResolvedUndefs) {
Solver.Solve();
- DEBUG(errs() << "RESOLVING UNDEFs\n");
+ DEBUG(dbgs() << "RESOLVING UNDEFs\n");
ResolvedUndefs = Solver.ResolvedUndefsIn(F);
}
if (Inst->getType()->isVoidTy() || isa<TerminatorInst>(Inst))
continue;
+ // TODO: Reconstruct structs from their elements.
+ if (Inst->getType()->isStructTy())
+ continue;
+
LatticeVal IV = Solver.getLatticeValueFor(Inst);
if (IV.isOverdefined())
continue;
Constant *Const = IV.isConstant()
? IV.getConstant() : UndefValue::get(Inst->getType());
- DEBUG(errs() << " Constant: " << *Const << " = " << *Inst);
+ DEBUG(dbgs() << " Constant: " << *Const << " = " << *Inst);
// Replaces all of the uses of a variable with uses of the constant.
Inst->replaceAllUsesWith(Const);
///
struct IPSCCP : public ModulePass {
static char ID;
- IPSCCP() : ModulePass(&ID) {}
+ IPSCCP() : ModulePass(ID) {
+ initializeIPSCCPPass(*PassRegistry::getPassRegistry());
+ }
bool runOnModule(Module &M);
};
} // end anonymous namespace
char IPSCCP::ID = 0;
-static RegisterPass<IPSCCP>
-Y("ipsccp", "Interprocedural Sparse Conditional Constant Propagation");
+INITIALIZE_PASS(IPSCCP, "ipsccp",
+ "Interprocedural Sparse Conditional Constant Propagation",
+ false, false)
// createIPSCCPPass - This is the public interface to this file.
ModulePass *llvm::createIPSCCPPass() {
}
-static bool AddressIsTaken(GlobalValue *GV) {
+static bool AddressIsTaken(const GlobalValue *GV) {
// Delete any dead constantexpr klingons.
GV->removeDeadConstantUsers();
- for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end();
- UI != E; ++UI)
- if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
+ for (Value::const_use_iterator UI = GV->use_begin(), E = GV->use_end();
+ UI != E; ++UI) {
+ const User *U = *UI;
+ if (const StoreInst *SI = dyn_cast<StoreInst>(U)) {
if (SI->getOperand(0) == GV || SI->isVolatile())
return true; // Storing addr of GV.
- } else if (isa<InvokeInst>(*UI) || isa<CallInst>(*UI)) {
+ } else if (isa<InvokeInst>(U) || isa<CallInst>(U)) {
// Make sure we are calling the function, not passing the address.
- if (UI.getOperandNo() != 0)
+ ImmutableCallSite CS(cast<Instruction>(U));
+ if (!CS.isCallee(UI))
return true;
- } else if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
+ } else if (const LoadInst *LI = dyn_cast<LoadInst>(U)) {
if (LI->isVolatile())
return true;
- } else if (isa<BlockAddress>(*UI)) {
+ } else if (isa<BlockAddress>(U)) {
// blockaddress doesn't take the address of the function, it takes addr
// of label.
} else {
return true;
}
+ }
return false;
}
bool IPSCCP::runOnModule(Module &M) {
SCCPSolver Solver(getAnalysisIfAvailable<TargetData>());
+ // AddressTakenFunctions - This set keeps track of the address-taken functions
+ // that are in the input. As IPSCCP runs through and simplifies code,
+ // functions that were address taken can end up losing their
+ // address-taken-ness. Because of this, we keep track of their addresses from
+ // the first pass so we can use them for the later simplification pass.
+ SmallPtrSet<Function*, 32> AddressTakenFunctions;
+
// 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()) {
+ if (AddressIsTaken(F))
+ AddressTakenFunctions.insert(F);
+ else {
+ 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.
while (ResolvedUndefs) {
Solver.Solve();
- DEBUG(errs() << "RESOLVING UNDEFS\n");
+ DEBUG(dbgs() << "RESOLVING UNDEFS\n");
ResolvedUndefs = false;
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F)
ResolvedUndefs |= Solver.ResolvedUndefsIn(*F);
if (Solver.isBlockExecutable(F->begin())) {
for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
AI != E; ++AI) {
- if (AI->use_empty()) continue;
+ if (AI->use_empty() || AI->getType()->isStructTy()) 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");
+ DEBUG(dbgs() << "*** Arg " << *AI << " = " << *CST <<"\n");
// Replaces all of the uses of a variable with uses of the
// constant.
for (BasicBlock::iterator BI = BB->begin(), E = BB->end(); BI != E; ) {
Instruction *Inst = BI++;
- if (Inst->getType()->isVoidTy())
+ if (Inst->getType()->isVoidTy() || Inst->getType()->isStructTy())
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;
Constant *Const = IV.isConstant()
? IV.getConstant() : UndefValue::get(Inst->getType());
- DEBUG(errs() << " Constant: " << *Const << " = " << *Inst);
+ DEBUG(dbgs() << " Constant: " << *Const << " = " << *Inst);
// Replaces all of the uses of a variable with uses of the
// constant.
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
// all call uses with the inferred value. This means we don't need to bother
// actually returning anything from the function. Replace all return
// instructions with return undef.
+ //
+ // Do this in two stages: first identify the functions we should process, then
+ // actually zap their returns. This is important because we can only do this
+ // if the address of the function isn't taken. In cases where a return is the
+ // last use of a function, the order of processing functions would affect
+ // whether other functions are optimizable.
+ SmallVector<ReturnInst*, 8> ReturnsToZap;
+
// 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() || AddressTakenFunctions.count(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)))
+ ReturnsToZap.push_back(RI);
+ }
+ // Zap all returns which we've identified as zap to change.
+ for (unsigned i = 0, e = ReturnsToZap.size(); i != e; ++i) {
+ Function *F = ReturnsToZap[i]->getParent()->getParent();
+ ReturnsToZap[i]->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();
GlobalVariable *GV = I->first;
assert(!I->second.isOverdefined() &&
"Overdefined values should have been taken out of the map!");
- DEBUG(errs() << "Found that GV '" << GV->getName() << "' is constant!\n");
+ DEBUG(dbgs() << "Found that GV '" << GV->getName() << "' is constant!\n");
while (!GV->use_empty()) {
StoreInst *SI = cast<StoreInst>(GV->use_back());
SI->eraseFromParent();
projects / oota-llvm.git / blobdiff