//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "sccp"
#include "llvm/Transforms/Scalar.h"
-#include "llvm/Transforms/IPO.h"
-#include "llvm/Constants.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/Instructions.h"
-#include "llvm/Pass.h"
-#include "llvm/Analysis/ConstantFolding.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/Support/InstVisitor.h"
-#include "llvm/Support/raw_ostream.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"
+#include "llvm/Analysis/GlobalsModRef.h"
+#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/IR/CallSite.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/InstVisitor.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/Transforms/Utils/Local.h"
#include <algorithm>
-#include <map>
using namespace llvm;
+#define DEBUG_TYPE "sccp"
+
STATISTIC(NumInstRemoved, "Number of instructions removed");
STATISTIC(NumDeadBlocks , "Number of basic blocks unreachable");
enum LatticeValueTy {
/// undefined - This LLVM Value has no known value yet.
undefined,
-
+
/// constant - This LLVM Value has a specific constant value.
constant,
/// with another (different) constant, it goes to overdefined, instead of
/// asserting.
forcedconstant,
-
+
/// overdefined - This instruction is not known to be constant, and we know
/// it has a value.
overdefined
/// Val: This stores the current lattice value along with the Constant* for
/// the constant if this is a 'constant' or 'forcedconstant' value.
PointerIntPair<Constant *, 2, LatticeValueTy> Val;
-
+
LatticeValueTy getLatticeValue() const {
return Val.getInt();
}
-
+
public:
- LatticeVal() : Val(0, undefined) {}
-
+ LatticeVal() : Val(nullptr, undefined) {}
+
bool isUndefined() const { return getLatticeValue() == undefined; }
bool isConstant() const {
return getLatticeValue() == constant || getLatticeValue() == forcedconstant;
}
bool isOverdefined() const { return getLatticeValue() == overdefined; }
-
+
Constant *getConstant() const {
assert(isConstant() && "Cannot get the constant of a non-constant!");
return Val.getPointer();
}
-
+
/// markOverdefined - Return true if this is a change in status.
bool markOverdefined() {
if (isOverdefined())
return false;
-
+
Val.setInt(overdefined);
return true;
}
assert(getConstant() == V && "Marking constant with different value");
return false;
}
-
+
if (isUndefined()) {
Val.setInt(constant);
assert(V && "Marking constant with NULL");
Val.setPointer(V);
} else {
- assert(getLatticeValue() == forcedconstant &&
+ assert(getLatticeValue() == forcedconstant &&
"Cannot move from overdefined to constant!");
// Stay at forcedconstant if the constant is the same.
if (V == getConstant()) return false;
-
+
// Otherwise, we go to overdefined. Assumptions made based on the
// forced value are possibly wrong. Assuming this is another constant
// could expose a contradiction.
ConstantInt *getConstantInt() const {
if (isConstant())
return dyn_cast<ConstantInt>(getConstant());
- return 0;
+ return nullptr;
}
-
+
void markForcedConstant(Constant *V) {
assert(isUndefined() && "Can't force a defined value!");
Val.setInt(forcedconstant);
/// Constant Propagation.
///
class SCCPSolver : public InstVisitor<SCCPSolver> {
- const TargetData *TD;
- SmallPtrSet<BasicBlock*, 8> BBExecutable;// The BBs that are executable.
+ const DataLayout &DL;
+ const TargetLibraryInfo *TLI;
+ 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;
/// 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.
SmallVector<BasicBlock*, 64> BBWorkList; // The BasicBlock work list
- /// UsersOfOverdefinedPHIs - Keep track of any users of PHI nodes that are not
- /// overdefined, despite the fact that the PHI node is overdefined.
- std::multimap<PHINode*, Instruction*> UsersOfOverdefinedPHIs;
-
/// KnownFeasibleEdges - Entries in this set are edges which have already had
/// PHI nodes retriggered.
typedef std::pair<BasicBlock*, BasicBlock*> Edge;
DenseSet<Edge> KnownFeasibleEdges;
public:
- SCCPSolver(const TargetData *td) : TD(td) {}
+ SCCPSolver(const DataLayout &DL, const TargetLibraryInfo *tli)
+ : DL(DL), TLI(tli) {}
/// 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.
///
/// This returns true if the block was not considered live before.
bool MarkBlockExecutable(BasicBlock *BB) {
- if (!BBExecutable.insert(BB)) return false;
- DEBUG(dbgs() << "Marking Block Executable: " << BB->getName() << "\n");
+ if (!BBExecutable.insert(BB).second)
+ return false;
+ DEBUG(dbgs() << "Marking Block Executable: " << BB->getName() << '\n');
BBWorkList.push_back(BB); // Add the block to the work list!
return true;
}
/// this method must be called.
void AddTrackedFunction(Function *F) {
// Add an entry, F -> undef.
- if (const StructType *STy = dyn_cast<StructType>(F->getReturnType())) {
+ if (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),
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.
///
/// 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()))
+ if (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(dbgs() << "markConstant: " << *C << ": " << *V << '\n');
- InstWorkList.push_back(V);
+ 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) {
assert(!V->getType()->isStructTy() && "Should use other method");
- ValueState[V].markForcedConstant(C);
+ LatticeVal &IV = ValueState[V];
+ IV.markForcedConstant(C);
DEBUG(dbgs() << "markForcedConstant: " << *C << ": " << *V << '\n');
- InstWorkList.push_back(V);
+ if (IV.isOverdefined())
+ OverdefinedInstWorkList.push_back(V);
+ else
+ 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.
void markOverdefined(LatticeVal &IV, Value *V) {
if (!IV.markOverdefined()) return;
-
+
DEBUG(dbgs() << "markOverdefined: ";
if (Function *F = dyn_cast<Function>(V))
dbgs() << "Function '" << F->getName() << "'\n";
else if (IV.getConstant() != MergeWithV.getConstant())
markOverdefined(IV, V);
}
-
+
void mergeInValue(Value *V, LatticeVal MergeWithV) {
assert(!V->getType()->isStructTy() && "Should use other method");
mergeInValue(ValueState[V], V, MergeWithV);
if (!isa<UndefValue>(V))
LV.markConstant(C); // Constants are constant
}
-
+
// All others are underdefined by default.
return LV;
}
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
+ Constant *Elt = C->getAggregateElement(i);
+
+ if (!Elt)
LV.markOverdefined(); // Unknown sort of constant.
+ else if (isa<UndefValue>(Elt))
+ ; // Undef values remain undefined.
+ else
+ LV.markConstant(Elt); // Constants are 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.
// feasible that wasn't before. Revisit the PHI nodes in the block
// because they have potentially new operands.
DEBUG(dbgs() << "Marking Edge Executable: " << Source->getName()
- << " -> " << Dest->getName() << "\n");
+ << " -> " << Dest->getName() << '\n');
PHINode *PN;
for (BasicBlock::iterator I = Dest->begin();
// getFeasibleSuccessors - Return a vector of booleans to indicate which
// successors are reachable from a given terminator instruction.
//
- void getFeasibleSuccessors(TerminatorInst &TI, SmallVector<bool, 16> &Succs);
+ void getFeasibleSuccessors(TerminatorInst &TI, SmallVectorImpl<bool> &Succs);
// isEdgeFeasible - Return true if the control flow edge from the 'From' basic
// block to the 'To' basic block is currently feasible.
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:
friend class InstVisitor<SCCPSolver>;
void visitShuffleVectorInst(ShuffleVectorInst &I);
void visitExtractValueInst(ExtractValueInst &EVI);
void visitInsertValueInst(InsertValueInst &IVI);
+ void visitLandingPadInst(LandingPadInst &I) { markAnythingOverdefined(&I); }
+ void visitFuncletPadInst(FuncletPadInst &FPI) {
+ markAnythingOverdefined(&FPI);
+ }
+ void visitCatchSwitchInst(CatchSwitchInst &CPI) {
+ markAnythingOverdefined(&CPI);
+ visitTerminatorInst(CPI);
+ }
// Instructions that cannot be folded away.
void visitStoreInst (StoreInst &I);
void visitLoadInst (LoadInst &I);
void visitGetElementPtrInst(GetElementPtrInst &I);
void visitCallInst (CallInst &I) {
- 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 visitResumeInst (TerminatorInst &I) { /*returns void*/ }
void visitUnreachableInst(TerminatorInst &I) { /*returns void*/ }
+ void visitFenceInst (FenceInst &I) { /*returns void*/ }
+ void visitAtomicCmpXchgInst(AtomicCmpXchgInst &I) {
+ markAnythingOverdefined(&I);
+ }
+ void visitAtomicRMWInst (AtomicRMWInst &I) { markOverdefined(&I); }
void visitAllocaInst (Instruction &I) { markOverdefined(&I); }
- void visitVANextInst (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.
- dbgs() << "SCCP: Don't know how to handle: " << I;
+ dbgs() << "SCCP: Don't know how to handle: " << I << '\n';
markAnythingOverdefined(&I); // Just in case
}
};
// successors are reachable from a given terminator instruction.
//
void SCCPSolver::getFeasibleSuccessors(TerminatorInst &TI,
- SmallVector<bool, 16> &Succs) {
+ SmallVectorImpl<bool> &Succs) {
Succs.resize(TI.getNumSuccessors());
if (BranchInst *BI = dyn_cast<BranchInst>(&TI)) {
if (BI->isUnconditional()) {
Succs[0] = true;
return;
}
-
+
LatticeVal BCValue = getValueState(BI->getCondition());
ConstantInt *CI = BCValue.getConstantInt();
- if (CI == 0) {
+ if (!CI) {
// Overdefined condition variables, and branches on unfoldable constant
// conditions, mean the branch could go either way.
if (!BCValue.isUndefined())
Succs[0] = Succs[1] = true;
return;
}
-
+
// Constant condition variables mean the branch can only go a single way.
Succs[CI->isZero()] = true;
return;
}
-
- if (isa<InvokeInst>(TI)) {
- // Invoke instructions successors are always executable.
- Succs[0] = Succs[1] = true;
+
+ // Unwinding instructions successors are always executable.
+ if (TI.isExceptional()) {
+ Succs.assign(TI.getNumSuccessors(), true);
return;
}
-
+
if (SwitchInst *SI = dyn_cast<SwitchInst>(&TI)) {
+ if (!SI->getNumCases()) {
+ Succs[0] = true;
+ return;
+ }
LatticeVal SCValue = getValueState(SI->getCondition());
ConstantInt *CI = SCValue.getConstantInt();
-
- if (CI == 0) { // Overdefined or undefined condition?
+
+ if (!CI) { // Overdefined or undefined condition?
// All destinations are executable!
if (!SCValue.isUndefined())
Succs.assign(TI.getNumSuccessors(), true);
return;
}
-
- Succs[SI->findCaseValue(CI)] = true;
+
+ Succs[SI->findCaseValue(CI).getSuccessorIndex()] = true;
return;
}
-
+
// TODO: This could be improved if the operand is a [cast of a] BlockAddress.
if (isa<IndirectBrInst>(&TI)) {
// Just mark all destinations executable!
Succs.assign(TI.getNumSuccessors(), true);
return;
}
-
+
#ifndef NDEBUG
dbgs() << "Unknown terminator instruction: " << TI << '\n';
#endif
if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
if (BI->isUnconditional())
return true;
-
+
LatticeVal BCValue = getValueState(BI->getCondition());
// Overdefined condition variables mean the branch could go either way,
// undef conditions mean that neither edge is feasible yet.
ConstantInt *CI = BCValue.getConstantInt();
- if (CI == 0)
+ if (!CI)
return !BCValue.isUndefined();
-
+
// Constant condition variables mean the branch can only go a single way.
return BI->getSuccessor(CI->isZero()) == To;
}
-
- // Invoke instructions successors are always executable.
- if (isa<InvokeInst>(TI))
+
+ // Unwinding instructions successors are always executable.
+ if (TI->isExceptional())
return true;
-
+
if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
+ if (SI->getNumCases() < 1)
+ return true;
+
LatticeVal SCValue = getValueState(SI->getCondition());
ConstantInt *CI = SCValue.getConstantInt();
-
- if (CI == 0)
- return !SCValue.isUndefined();
- // Make sure to skip the "default value" which isn't a value
- for (unsigned i = 1, E = SI->getNumSuccessors(); i != E; ++i)
- if (SI->getSuccessorValue(i) == CI) // Found the taken branch.
- return SI->getSuccessor(i) == To;
+ if (!CI)
+ return !SCValue.isUndefined();
- // If the constant value is not equal to any of the branches, we must
- // execute default branch.
- return SI->getDefaultDest() == To;
+ return SI->findCaseValue(CI).getCaseSuccessor() == To;
}
-
+
// Just mark all destinations executable!
// TODO: This could be improved if the operand is a [cast of a] BlockAddress.
- if (isa<IndirectBrInst>(&TI))
+ if (isa<IndirectBrInst>(TI))
return true;
-
+
#ifndef NDEBUG
dbgs() << "Unknown terminator instruction: " << *TI << '\n';
#endif
- llvm_unreachable(0);
+ llvm_unreachable("SCCP: Don't know how to handle this terminator!");
}
// visit Implementations - Something changed in this instruction, either an
// 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
- // changed.
- std::multimap<PHINode*, Instruction*>::iterator I, E;
- tie(I, E) = UsersOfOverdefinedPHIs.equal_range(&PN);
- 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());
+
+ if (getValueState(&PN).isOverdefined())
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(&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. If they are constant and don't agree, the PHI is overdefined.
// If there are no executable operands, the PHI remains undefined.
//
- Constant *OperandVal = 0;
+ Constant *OperandVal = nullptr;
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
LatticeVal IV = getValueState(PN.getIncomingValue(i));
if (IV.isUndefined()) continue; // Doesn't influence PHI node.
if (!isEdgeFeasible(PN.getIncomingBlock(i), PN.getParent()))
continue;
-
+
if (IV.isOverdefined()) // PHI node becomes overdefined!
return markOverdefined(&PN);
- if (OperandVal == 0) { // Grab the first value.
+ if (!OperandVal) { // Grab the first value.
OperandVal = IV.getConstant();
continue;
}
-
+
// There is already a reachable operand. If we conflict with it,
// then the PHI node becomes overdefined. If we agree with it, we
// can continue on.
-
+
// Check to see if there are two different constants merging, if so, the PHI
// node is overdefined.
if (IV.getConstant() != OperandVal)
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 (!TrackedRetVals.empty() && !ResultOp->getType()->isStructTy()) {
DenseMap<Function*, LatticeVal>::iterator TFRVI =
return;
}
}
-
+
// Handle functions that return multiple values.
if (!TrackedMultipleRetVals.empty()) {
- if (const StructType *STy = dyn_cast<StructType>(ResultOp->getType()))
+ if (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));
-
+
}
}
if (OpSt.isOverdefined()) // Inherit overdefinedness of operand
markOverdefined(&I);
else if (OpSt.isConstant()) // Propagate constant value
- markConstant(&I, ConstantExpr::getCast(I.getOpcode(),
+ markConstant(&I, ConstantExpr::getCast(I.getOpcode(),
OpSt.getConstant(), I.getType()));
}
// 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);
}
void SCCPSolver::visitInsertValueInst(InsertValueInst &IVI) {
- const StructType *STy = dyn_cast<StructType>(IVI.getType());
- if (STy == 0)
+ StructType *STy = dyn_cast<StructType>(IVI.getType());
+ if (!STy)
return 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.
mergeInValue(getStructValueState(&IVI, i), &IVI, EltVal);
continue;
}
-
+
Value *Val = IVI.getInsertedValueOperand();
if (Val->getType()->isStructTy())
// We don't track structs in structs.
// 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 (ConstantInt *CondCB = CondValue.getConstantInt()) {
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());
-
+
// select ?, C, C -> C.
- if (TVal.isConstant() && FVal.isConstant() &&
+ if (TVal.isConstant() && FVal.isConstant() &&
TVal.getConstant() == FVal.getConstant())
return markConstant(&I, FVal.getConstant());
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;
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;
+ LatticeVal *NonOverdefVal = nullptr;
if (!V1State.isOverdefined())
NonOverdefVal = &V1State;
else if (!V2State.isOverdefined())
// 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()))
+ else if (VectorType *PT = dyn_cast<VectorType>(I.getType()))
markConstant(IV, &I, Constant::getAllOnesValue(PT));
else
markConstant(IV, &I,
Constant::getAllOnesValue(I.getType()));
return;
}
-
+
if (I.getOpcode() == Instruction::And) {
// X and 0 = 0
if (NonOverdefVal->getConstant()->isNullValue())
}
- // 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;
- }
- }
- }
-
- // 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;
-
- // 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);
}
if (IV.isOverdefined()) return;
if (V1State.isConstant() && V2State.isConstant())
- return markConstant(IV, &I, ConstantExpr::getCompare(I.getPredicate(),
- V1State.getConstant(),
+ 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;
- }
- }
- }
-
- // 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;
-
- // 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);
}
EltState.getConstant(),
IdxState.getConstant()));
else if (ValState.isUndefined() && EltState.isConstant() &&
- IdxState.isConstant())
+ IdxState.isConstant())
markConstant(&I,ConstantExpr::getInsertElement(UndefValue::get(I.getType()),
EltState.getConstant(),
IdxState.getConstant()));
if (MaskState.isUndefined() ||
(V1State.isUndefined() && V2State.isUndefined()))
return; // Undefined output if mask or both inputs undefined.
-
+
if (V1State.isOverdefined() || V2State.isOverdefined() ||
MaskState.isOverdefined()) {
markOverdefined(&I);
} else {
// A mix of constant/undef inputs.
- Constant *V1 = V1State.isConstant() ?
+ Constant *V1 = V1State.isConstant() ?
V1State.getConstant() : UndefValue::get(I.getType());
- Constant *V2 = V2State.isConstant() ?
+ Constant *V2 = V2State.isConstant() ?
V2State.getConstant() : UndefValue::get(I.getType());
- Constant *Mask = MaskState.isConstant() ?
+ Constant *Mask = MaskState.isConstant() ?
MaskState.getConstant() : UndefValue::get(I.getOperand(2)->getType());
markConstant(&I, ConstantExpr::getShuffleVector(V1, V2, Mask));
}
LatticeVal State = getValueState(I.getOperand(i));
if (State.isUndefined())
return; // Operands are not resolved yet.
-
+
if (State.isOverdefined())
return markOverdefined(&I);
}
Constant *Ptr = Operands[0];
- markConstant(&I, ConstantExpr::getGetElementPtr(Ptr, &Operands[0]+1,
- Operands.size()-1));
+ auto Indices = makeArrayRef(Operands.begin() + 1, Operands.end());
+ markConstant(&I, ConstantExpr::getGetElementPtr(I.getSourceElementType(), Ptr,
+ Indices));
}
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;
-
+
GlobalVariable *GV = cast<GlobalVariable>(SI.getOperand(1));
DenseMap<GlobalVariable*, LatticeVal>::iterator I = TrackedGlobals.find(GV);
if (I == TrackedGlobals.end() || I->second.isOverdefined()) return;
// 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!
-
+
LatticeVal &IV = ValueState[&I];
if (IV.isOverdefined()) return;
if (!PtrVal.isConstant() || I.isVolatile())
return markOverdefined(IV, &I);
-
+
Constant *Ptr = PtrVal.getConstant();
- // load null -> null
+ // load null is undefined.
if (isa<ConstantPointerNull>(Ptr) && I.getPointerAddressSpace() == 0)
- return markConstant(IV, &I, Constant::getNullValue(I.getType()));
-
+ return;
+
// Transform load (constant global) into the value loaded.
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Ptr)) {
if (!TrackedGlobals.empty()) {
}
// Transform load from a constant into a constant if possible.
- if (Constant *C = ConstantFoldLoadFromConstPtr(Ptr, TD))
+ if (Constant *C = ConstantFoldLoadFromConstPtr(Ptr, DL))
return markConstant(IV, &I, C);
// Otherwise we cannot say for certain what value this load will produce.
void SCCPSolver::visitCallSite(CallSite CS) {
Function *F = CS.getCalledFunction();
Instruction *I = CS.getInstruction();
-
+
// 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->isDeclaration()) {
+ if (!F || 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 (F && F->isDeclaration() && !I->getType()->isStructTy() &&
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);
-
+
if (State.isUndefined())
return; // Operands are not resolved yet.
if (State.isOverdefined())
assert(State.isConstant() && "Unknown state!");
Operands.push_back(State.getConstant());
}
-
+
+ if (getValueState(I).isOverdefined())
+ return;
+
// If we can constant fold this, mark the result of the call as a
// constant.
- if (Constant *C = ConstantFoldCall(F, Operands.data(), Operands.size()))
+ if (Constant *C = ConstantFoldCall(F, Operands, TLI))
return markConstant(I, C);
}
// 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());
-
+ MarkBlockExecutable(&F->front());
+
// 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();
// 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);
+ markOverdefined(&*AI);
continue;
}
-
- if (const StructType *STy = dyn_cast<StructType>(AI->getType())) {
+
+ if (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);
+ mergeInValue(getStructValueState(&*AI, i), &*AI, CallArg);
}
} else {
- mergeInValue(AI, getValueState(*CAI));
+ mergeInValue(&*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 (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,
+ 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);
}
DEBUG(dbgs() << "\nPopped off OI-WL: " << *I << '\n');
// "I" got into the work list because it either made the transition from
- // bottom to constant
+ // bottom to constant, or to overdefined.
//
// 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.
//
- for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
- UI != E; ++UI)
- if (Instruction *I = dyn_cast<Instruction>(*UI))
- OperandChangedState(I);
+ for (User *U : I->users())
+ if (Instruction *UI = dyn_cast<Instruction>(U))
+ OperandChangedState(UI);
}
-
+
// Process the instruction work list.
while (!InstWorkList.empty()) {
Value *I = InstWorkList.pop_back_val();
// Update all of the users of this instruction's value.
//
if (I->getType()->isStructTy() || !getValueState(I).isOverdefined())
- for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
- UI != E; ++UI)
- if (Instruction *I = dyn_cast<Instruction>(*UI))
- OperandChangedState(I);
+ for (User *U : I->users())
+ if (Instruction *UI = dyn_cast<Instruction>(U))
+ OperandChangedState(UI);
}
// Process the basic block work list.
/// even if X isn't defined.
bool SCCPSolver::ResolvedUndefsIn(Function &F) {
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
- if (!BBExecutable.count(BB))
+ if (!BBExecutable.count(&*BB))
continue;
-
- for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
+
+ for (Instruction &I : *BB) {
// 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);
- }
+ if (I.getType()->isVoidTy()) continue;
+
+ if (StructType *STy = dyn_cast<StructType>(I.getType())) {
+ // Only a few things that can be structs matter for undef.
+
+ // Tracked calls must never be marked overdefined in ResolvedUndefsIn.
+ if (CallSite CS = CallSite(&I))
+ if (Function *F = CS.getCalledFunction())
+ if (MRVFunctionsTracked.count(F))
+ continue;
+
+ // extractvalue and insertvalue don't need to be marked; they are
+ // tracked as precisely as their operands.
+ if (isa<ExtractValueInst>(I) || isa<InsertValueInst>(I))
+ continue;
+
+ // Send the results of everything else to overdefined. We could be
+ // more precise than this but it isn't worth bothering.
+ 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);
+
+ LatticeVal &LV = getValueState(&I);
if (!LV.isUndefined()) continue;
- // No instructions using structs need disambiguation.
- if (I->getOperand(0)->getType()->isStructTy())
+ // extractvalue is safe; check here because the argument is a struct.
+ if (isa<ExtractValueInst>(I))
continue;
- // Get the lattice values of the first two operands for use below.
- LatticeVal Op0LV = getValueState(I->getOperand(0));
+ // Compute the operand LatticeVals, for convenience below.
+ // Anything taking a struct is conservatively assumed to require
+ // overdefined markings.
+ if (I.getOperand(0)->getType()->isStructTy()) {
+ markOverdefined(&I);
+ return true;
+ }
+ 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));
- if (Op0LV.isUndefined() && Op1LV.isUndefined())
- continue;
+ if (I.getNumOperands() == 2) {
+ if (I.getOperand(1)->getType()->isStructTy()) {
+ markOverdefined(&I);
+ return true;
+ }
+
+ Op1LV = getValueState(I.getOperand(1));
}
-
// If this is an instructions whose result is defined even if the input is
// not fully defined, propagate the information.
- const Type *ITy = I->getType();
- switch (I->getOpcode()) {
- default: break; // Leave the instruction as an undef.
+ Type *ITy = I.getType();
+ switch (I.getOpcode()) {
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Trunc:
+ case Instruction::FPTrunc:
+ case Instruction::BitCast:
+ break; // Any undef -> undef
+ case Instruction::FSub:
+ case Instruction::FAdd:
+ case Instruction::FMul:
+ case Instruction::FDiv:
+ case Instruction::FRem:
+ // Floating-point binary operation: be conservative.
+ if (Op0LV.isUndefined() && Op1LV.isUndefined())
+ markForcedConstant(&I, Constant::getNullValue(ITy));
+ else
+ markOverdefined(&I);
+ return true;
case Instruction::ZExt:
- // 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.
- markForcedConstant(I, Constant::getNullValue(ITy));
+ case Instruction::SExt:
+ case Instruction::FPToUI:
+ case Instruction::FPToSI:
+ case Instruction::FPExt:
+ case Instruction::PtrToInt:
+ case Instruction::IntToPtr:
+ case Instruction::SIToFP:
+ case Instruction::UIToFP:
+ // undef -> 0; some outputs are impossible
+ markForcedConstant(&I, Constant::getNullValue(ITy));
return true;
case Instruction::Mul:
case Instruction::And:
+ // Both operands undef -> undef
+ if (Op0LV.isUndefined() && Op1LV.isUndefined())
+ break;
// undef * X -> 0. X could be zero.
// undef & X -> 0. X could be zero.
- markForcedConstant(I, Constant::getNullValue(ITy));
+ markForcedConstant(&I, Constant::getNullValue(ITy));
return true;
case Instruction::Or:
+ // Both operands undef -> undef
+ if (Op0LV.isUndefined() && Op1LV.isUndefined())
+ break;
// undef | X -> -1. X could be -1.
- markForcedConstant(I, Constant::getAllOnesValue(ITy));
+ markForcedConstant(&I, Constant::getAllOnesValue(ITy));
return true;
+ case Instruction::Xor:
+ // undef ^ undef -> 0; strictly speaking, this is not strictly
+ // necessary, but we try to be nice to people who expect this
+ // behavior in simple cases
+ if (Op0LV.isUndefined() && Op1LV.isUndefined()) {
+ markForcedConstant(&I, Constant::getNullValue(ITy));
+ return true;
+ }
+ // undef ^ X -> undef
+ break;
+
case Instruction::SDiv:
case Instruction::UDiv:
case Instruction::SRem:
// X / undef -> undef. No change.
// X % undef -> undef. No change.
if (Op1LV.isUndefined()) break;
-
+
// undef / X -> 0. X could be maxint.
// undef % X -> 0. X could be 1.
- markForcedConstant(I, Constant::getNullValue(ITy));
+ markForcedConstant(&I, Constant::getNullValue(ITy));
return true;
-
+
case Instruction::AShr:
- // undef >>s X -> undef. No change.
- if (Op0LV.isUndefined()) break;
-
- // X >>s undef -> X. X could be 0, X could have the high-bit known set.
- if (Op0LV.isConstant())
- markForcedConstant(I, Op0LV.getConstant());
- else
- markOverdefined(I);
+ // X >>a undef -> undef.
+ if (Op1LV.isUndefined()) break;
+
+ // undef >>a X -> all ones
+ markForcedConstant(&I, Constant::getAllOnesValue(ITy));
return true;
case Instruction::LShr:
case Instruction::Shl:
- // undef >> X -> undef. No change.
- // undef << X -> undef. No change.
- if (Op0LV.isUndefined()) break;
-
- // X >> undef -> 0. X could be 0.
- // X << undef -> 0. X could be 0.
- markForcedConstant(I, Constant::getNullValue(ITy));
+ // X << undef -> undef.
+ // X >> undef -> undef.
+ if (Op1LV.isUndefined()) break;
+
+ // undef << X -> 0
+ // undef >> X -> 0
+ markForcedConstant(&I, Constant::getNullValue(ITy));
return true;
case Instruction::Select:
+ Op1LV = getValueState(I.getOperand(1));
// undef ? X : Y -> X or Y. There could be commonality between X/Y.
if (Op0LV.isUndefined()) {
if (!Op1LV.isConstant()) // Pick the constant one if there is any.
- Op1LV = getValueState(I->getOperand(2));
+ Op1LV = getValueState(I.getOperand(2));
} else if (Op1LV.isUndefined()) {
// c ? undef : undef -> undef. No change.
- Op1LV = getValueState(I->getOperand(2));
+ Op1LV = getValueState(I.getOperand(2));
if (Op1LV.isUndefined())
break;
// Otherwise, c ? undef : x -> x.
} else {
// Leave Op1LV as Operand(1)'s LatticeValue.
}
-
+
if (Op1LV.isConstant())
- markForcedConstant(I, Op1LV.getConstant());
+ markForcedConstant(&I, Op1LV.getConstant());
else
- markOverdefined(I);
+ markOverdefined(&I);
+ return true;
+ case Instruction::Load:
+ // A load here means one of two things: a load of undef from a global,
+ // a load from an unknown pointer. Either way, having it return undef
+ // is okay.
+ break;
+ case Instruction::ICmp:
+ // X == undef -> undef. Other comparisons get more complicated.
+ if (cast<ICmpInst>(&I)->isEquality())
+ break;
+ 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
+ case Instruction::Invoke: {
+ // There are two reasons a call can have an undef result
+ // 1. It could be tracked.
+ // 2. It could be constant-foldable.
+ // Because of the way we solve return values, tracked calls must
+ // never be marked overdefined in ResolvedUndefsIn.
+ if (Function *F = CallSite(&I).getCalledFunction())
+ if (TrackedRetVals.count(F))
+ break;
+
+ // If the call is constant-foldable, we mark it overdefined because
+ // we do not know what return values are valid.
+ markOverdefined(&I);
+ return true;
+ }
+ default:
+ // If we don't know what should happen here, conservatively mark it
// overdefined.
- markOverdefined(I);
+ markOverdefined(&I);
return true;
}
}
-
+
+ // 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 (SI->getNumSuccessors() < 2) // no cases
+
+ // 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->getNumCases())
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->case_begin().getCaseValue());
+ markEdgeExecutable(&*BB, SI->case_begin().getCaseSuccessor());
+ return true;
+ }
+
+ markForcedConstant(SI->getCondition(), SI->case_begin().getCaseValue());
+ return true;
}
-
- return true;
}
return false;
/// Sparse Conditional Constant Propagator.
///
struct SCCP : public FunctionPass {
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.addRequired<TargetLibraryInfoWrapperPass>();
+ AU.addPreserved<GlobalsAAWrapperPass>();
+ }
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.
//
- bool runOnFunction(Function &F);
-
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.setPreservesCFG();
- }
+ bool runOnFunction(Function &F) override;
};
} // 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(dbgs() << " BasicBlock Dead:" << *BB);
++NumDeadBlocks;
-
- // Delete the instructions backwards, as it has a reduced likelihood of
- // having to update as many def-use and use-def chains.
- while (!isa<TerminatorInst>(BB->begin())) {
- Instruction *I = --BasicBlock::iterator(BB->getTerminator());
-
- if (!I->use_empty())
- I->replaceAllUsesWith(UndefValue::get(I->getType()));
- BB->getInstList().erase(I);
+
+ // Check to see if there are non-terminating instructions to delete.
+ if (isa<TerminatorInst>(BB->begin()))
+ return;
+
+ // Delete the instructions backwards, as it has a reduced likelihood of having
+ // to update as many def-use and use-def chains.
+ Instruction *EndInst = BB->getTerminator(); // Last not to be deleted.
+ while (EndInst != BB->begin()) {
+ // Delete the next to last instruction.
+ Instruction *Inst = &*--EndInst->getIterator();
+ if (!Inst->use_empty())
+ Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
+ if (Inst->isEHPad()) {
+ EndInst = Inst;
+ continue;
+ }
+ BB->getInstList().erase(Inst);
++NumInstRemoved;
}
}
// and return true if the function was modified.
//
bool SCCP::runOnFunction(Function &F) {
+ if (skipOptnoneFunction(F))
+ return false;
+
DEBUG(dbgs() << "SCCP on function '" << F.getName() << "'\n");
- SCCPSolver Solver(getAnalysisIfAvailable<TargetData>());
+ const DataLayout &DL = F.getParent()->getDataLayout();
+ const TargetLibraryInfo *TLI =
+ &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
+ SCCPSolver Solver(DL, TLI);
// Mark the first block of the function as being executable.
- Solver.MarkBlockExecutable(F.begin());
+ Solver.MarkBlockExecutable(&F.front());
// 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.markAnythingOverdefined(AI);
+ for (Argument &AI : F.args())
+ Solver.markAnythingOverdefined(&AI);
// Solve for constants.
bool ResolvedUndefs = true;
// as we cannot modify the CFG of the function.
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
- if (!Solver.isBlockExecutable(BB)) {
- DeleteInstructionInBlock(BB);
+ if (!Solver.isBlockExecutable(&*BB)) {
+ DeleteInstructionInBlock(&*BB);
MadeChanges = true;
continue;
}
-
+
// Iterate over all of the instructions in a function, replacing them with
// constants if we have found them to be of constant values.
//
for (BasicBlock::iterator BI = BB->begin(), E = BB->end(); BI != E; ) {
- Instruction *Inst = BI++;
+ Instruction *Inst = &*BI++;
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(dbgs() << " Constant: " << *Const << " = " << *Inst);
+ DEBUG(dbgs() << " Constant: " << *Const << " = " << *Inst << '\n');
// Replaces all of the uses of a variable with uses of the constant.
Inst->replaceAllUsesWith(Const);
-
+
// Delete the instruction.
Inst->eraseFromParent();
-
+
// Hey, we just changed something!
MadeChanges = true;
++NumInstRemoved;
/// Constant Propagation.
///
struct IPSCCP : public ModulePass {
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.addRequired<TargetLibraryInfoWrapperPass>();
+ }
static char ID;
- IPSCCP() : ModulePass(&ID) {}
- bool runOnModule(Module &M);
+ IPSCCP() : ModulePass(ID) {
+ initializeIPSCCPPass(*PassRegistry::getPassRegistry());
+ }
+ bool runOnModule(Module &M) override;
};
} // end anonymous namespace
char IPSCCP::ID = 0;
-static RegisterPass<IPSCCP>
-Y("ipsccp", "Interprocedural Sparse Conditional Constant Propagation");
+INITIALIZE_PASS_BEGIN(IPSCCP, "ipsccp",
+ "Interprocedural Sparse Conditional Constant Propagation",
+ false, false)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
+INITIALIZE_PASS_END(IPSCCP, "ipsccp",
+ "Interprocedural Sparse Conditional Constant Propagation",
+ false, false)
// createIPSCCPPass - This is the public interface to this file.
ModulePass *llvm::createIPSCCPPass() {
// Delete any dead constantexpr klingons.
GV->removeDeadConstantUsers();
- for (Value::use_const_iterator UI = GV->use_begin(), E = GV->use_end();
- UI != E; ++UI) {
- const User *U = *UI;
- if (const StoreInst *SI = dyn_cast<StoreInst>(U)) {
+ for (const Use &U : GV->uses()) {
+ const User *UR = U.getUser();
+ if (const StoreInst *SI = dyn_cast<StoreInst>(UR)) {
if (SI->getOperand(0) == GV || SI->isVolatile())
return true; // Storing addr of GV.
- } else if (isa<InvokeInst>(U) || isa<CallInst>(U)) {
+ } else if (isa<InvokeInst>(UR) || isa<CallInst>(UR)) {
// Make sure we are calling the function, not passing the address.
- if (UI.getOperandNo() != 0)
+ ImmutableCallSite CS(cast<Instruction>(UR));
+ if (!CS.isCallee(&U))
return true;
- } else if (const LoadInst *LI = dyn_cast<LoadInst>(U)) {
+ } else if (const LoadInst *LI = dyn_cast<LoadInst>(UR)) {
if (LI->isVolatile())
return true;
- } else if (isa<BlockAddress>(U)) {
+ } else if (isa<BlockAddress>(UR)) {
// blockaddress doesn't take the address of the function, it takes addr
// of label.
} else {
}
bool IPSCCP::runOnModule(Module &M) {
- SCCPSolver Solver(getAnalysisIfAvailable<TargetData>());
+ const DataLayout &DL = M.getDataLayout();
+ const TargetLibraryInfo *TLI =
+ &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
+ SCCPSolver Solver(DL, TLI);
+
+ // 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->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);
-
+ 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;
+ if (F->hasLocalLinkage()) {
+ if (AddressIsTaken(&*F))
+ AddressTakenFunctions.insert(&*F);
+ else {
+ Solver.AddArgumentTrackedFunction(&*F);
+ continue;
+ }
}
// Assume the function is called.
- Solver.MarkBlockExecutable(F->begin());
-
+ Solver.MarkBlockExecutable(&F->front());
+
// Assume nothing about the incoming arguments.
- for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
- AI != E; ++AI)
- Solver.markAnythingOverdefined(AI);
+ for (Argument &AI : F->args())
+ 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.
- for (Module::global_iterator G = M.global_begin(), E = M.global_end();
- G != E; ++G)
- if (!G->isConstant() && G->hasLocalLinkage() && !AddressIsTaken(G))
- Solver.TrackValueOfGlobalVariable(G);
+ for (GlobalVariable &G : M.globals())
+ if (!G.isConstant() && G.hasLocalLinkage() && !AddressIsTaken(&G))
+ Solver.TrackValueOfGlobalVariable(&G);
// Solve for constants.
bool ResolvedUndefs = true;
SmallVector<BasicBlock*, 512> BlocksToErase;
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
- if (Solver.isBlockExecutable(F->begin())) {
+ if (F->isDeclaration())
+ continue;
+
+ if (Solver.isBlockExecutable(&F->front())) {
for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
AI != E; ++AI) {
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);
+ LatticeVal IV = Solver.getLatticeValueFor(&*AI);
if (IV.isOverdefined()) continue;
-
+
Constant *CST = IV.isConstant() ?
IV.getConstant() : UndefValue::get(AI->getType());
DEBUG(dbgs() << "*** Arg " << *AI << " = " << *CST <<"\n");
-
+
// Replaces all of the uses of a variable with uses of the
// constant.
AI->replaceAllUsesWith(CST);
}
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
- if (!Solver.isBlockExecutable(BB)) {
- DeleteInstructionInBlock(BB);
+ if (!Solver.isBlockExecutable(&*BB)) {
+ DeleteInstructionInBlock(&*BB);
MadeChanges = true;
TerminatorInst *TI = BB->getTerminator();
- for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) {
- BasicBlock *Succ = TI->getSuccessor(i);
+ for (BasicBlock *Succ : TI->successors()) {
if (!Succ->empty() && isa<PHINode>(Succ->begin()))
- TI->getSuccessor(i)->removePredecessor(BB);
+ Succ->removePredecessor(&*BB);
}
if (!TI->use_empty())
TI->replaceAllUsesWith(UndefValue::get(TI->getType()));
TI->eraseFromParent();
+ new UnreachableInst(M.getContext(), &*BB);
if (&*BB != &F->front())
- BlocksToErase.push_back(BB);
- else
- new UnreachableInst(M.getContext(), BB);
+ BlocksToErase.push_back(&*BB);
continue;
}
-
+
for (BasicBlock::iterator BI = BB->begin(), E = BB->end(); BI != E; ) {
- Instruction *Inst = BI++;
+ Instruction *Inst = &*BI++;
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(dbgs() << " Constant: " << *Const << " = " << *Inst);
+ DEBUG(dbgs() << " Constant: " << *Const << " = " << *Inst << '\n');
// Replaces all of the uses of a variable with uses of the
// constant.
Inst->replaceAllUsesWith(Const);
-
+
// Delete the instruction.
if (!isa<CallInst>(Inst) && !isa<TerminatorInst>(Inst))
Inst->eraseFromParent();
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];
- for (Value::use_iterator UI = DeadBB->use_begin(), UE = DeadBB->use_end();
- UI != UE; ) {
+ for (Value::user_iterator UI = DeadBB->user_begin(),
+ UE = DeadBB->user_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);
llvm_unreachable("Didn't fold away reference to block!");
}
#endif
-
+
// Make this an uncond branch to the first successor.
TerminatorInst *TI = I->getParent()->getTerminator();
BranchInst::Create(TI->getSuccessor(0), TI);
-
+
// Remove entries in successor phi nodes to remove edges.
for (unsigned i = 1, e = TI->getNumSuccessors(); i != e; ++i)
TI->getSuccessor(i)->removePredecessor(TI->getParent());
-
+
// Remove the old terminator.
TI->eraseFromParent();
}
// 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(),
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))
+ 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)))
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.
+
+ // If we inferred 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();
for (DenseMap<GlobalVariable*, LatticeVal>::const_iterator I = TG.begin(),
E = TG.end(); I != E; ++I) {
"Overdefined values should have been taken out of the map!");
DEBUG(dbgs() << "Found that GV '" << GV->getName() << "' is constant!\n");
while (!GV->use_empty()) {
- StoreInst *SI = cast<StoreInst>(GV->use_back());
+ StoreInst *SI = cast<StoreInst>(GV->user_back());
SI->eraseFromParent();
}
M.getGlobalList().erase(GV);
projects / oota-llvm.git / blobdiff