//===- SCCP.cpp - Sparse Conditional Constant Propagation -----------------===//
-//
+//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
-//
+//
//===----------------------------------------------------------------------===//
//
// This file implements sparse conditional constant propagation and merging:
namespace {
class LatticeVal {
- enum {
+ enum {
undefined, // This instruction has no known value
constant, // This instruction has a constant value
overdefined // This instruction has an unknown value
/// MarkBlockExecutable - This method can be used by clients to mark all of
/// the blocks that are known to be intrinsically live in the processed unit.
void MarkBlockExecutable(BasicBlock *BB) {
- DEBUG(std::cerr << "Marking Block Executable: " << BB->getName() << "\n");
+ DOUT << "Marking Block Executable: " << BB->getName() << "\n";
BBExecutable.insert(BB); // Basic block is executable!
BBWorkList.push_back(BB); // Add the block to the work list!
}
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
+ // is not already a constant, add it to the instruction work list so that
// the users of the instruction are updated later.
//
inline void markConstant(LatticeVal &IV, Value *V, Constant *C) {
if (IV.markConstant(C)) {
- DEBUG(std::cerr << "markConstant: " << *C << ": " << *V);
+ DOUT << "markConstant: " << *C << ": " << *V;
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
+ // value is not already overdefined, add it to the overdefined instruction
// work list so that the users of the instruction are updated later.
-
+
inline void markOverdefined(LatticeVal &IV, Value *V) {
if (IV.markOverdefined()) {
- DEBUG(std::cerr << "markOverdefined: ";
+ DEBUG(DOUT << "markOverdefined: ";
if (Function *F = dyn_cast<Function>(V))
- std::cerr << "Function '" << F->getName() << "'\n";
+ DOUT << "Function '" << F->getName() << "'\n";
else
- std::cerr << *V);
+ DOUT << *V);
// Only instructions go on the work list
OverdefinedInstWorkList.push_back(V);
}
else if (IV.getConstant() != MergeWithV.getConstant())
markOverdefined(IV, V);
}
+
+ inline void mergeInValue(Value *V, LatticeVal &MergeWithV) {
+ return mergeInValue(ValueState[V], V, MergeWithV);
+ }
+
// getValueState - Return the LatticeVal object that corresponds to the value.
// This function is necessary because not all values should start out in the
return ValueState[V];
}
- // markEdgeExecutable - Mark a basic block as executable, adding it to the BB
+ // markEdgeExecutable - Mark a basic block as executable, adding it to the BB
// work list if it is not already executable...
- //
+ //
void markEdgeExecutable(BasicBlock *Source, BasicBlock *Dest) {
if (!KnownFeasibleEdges.insert(Edge(Source, Dest)).second)
return; // This edge is already known to be executable!
if (BBExecutable.count(Dest)) {
- DEBUG(std::cerr << "Marking Edge Executable: " << Source->getName()
- << " -> " << Dest->getName() << "\n");
+ DOUT << "Marking Edge Executable: " << Source->getName()
+ << " -> " << Dest->getName() << "\n";
// The destination is already executable, but we just made an edge
// feasible that wasn't before. Revisit the PHI nodes in the block
private:
friend class InstVisitor<SCCPSolver>;
- // visit implementations - Something changed in this instruction... Either an
+ // visit implementations - Something changed in this instruction... Either an
// operand made a transition, or the instruction is newly executable. Change
// the value type of I to reflect these changes if appropriate.
//
void visitSelectInst(SelectInst &I);
void visitBinaryOperator(Instruction &I);
void visitShiftInst(ShiftInst &I) { visitBinaryOperator(I); }
+ void visitExtractElementInst(ExtractElementInst &I);
+ void visitInsertElementInst(InsertElementInst &I);
+ void visitShuffleVectorInst(ShuffleVectorInst &I);
// Instructions that cannot be folded away...
void visitStoreInst (Instruction &I);
void visitInstruction(Instruction &I) {
// If a new instruction is added to LLVM that we don't handle...
- std::cerr << "SCCP: Don't know how to handle: " << I;
+ cerr << "SCCP: Don't know how to handle: " << I;
markOverdefined(&I); // Just in case
}
};
Succs[0] = Succs[1] = true;
} else if (BCValue.isConstant()) {
// Constant condition variables mean the branch can only go a single way
- Succs[BCValue.getConstant() == ConstantBool::False] = true;
+ Succs[BCValue.getConstant() == ConstantBool::getFalse()] = true;
}
}
- } else if (InvokeInst *II = dyn_cast<InvokeInst>(&TI)) {
+ } else if (isa<InvokeInst>(&TI)) {
// Invoke instructions successors are always executable.
Succs[0] = Succs[1] = true;
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(&TI)) {
Succs[0] = true;
}
} else {
- std::cerr << "SCCP: Don't know how to handle: " << TI;
+ cerr << "SCCP: Don't know how to handle: " << TI;
Succs.assign(TI.getNumSuccessors(), true);
}
}
// Make sure the source basic block is executable!!
if (!BBExecutable.count(From)) return false;
-
+
// Check to make sure this edge itself is actually feasible now...
TerminatorInst *TI = From->getTerminator();
if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
if (!isa<ConstantBool>(BCValue.getConstant())) return true;
// Constant condition variables mean the branch can only go a single way
- return BI->getSuccessor(BCValue.getConstant() ==
- ConstantBool::False) == To;
+ return BI->getSuccessor(BCValue.getConstant() ==
+ ConstantBool::getFalse()) == To;
}
return false;
}
- } else if (InvokeInst *II = dyn_cast<InvokeInst>(TI)) {
+ } else if (isa<InvokeInst>(TI)) {
// Invoke instructions successors are always executable.
return true;
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
}
return false;
} else {
- std::cerr << "Unknown terminator instruction: " << *TI;
+ cerr << "Unknown terminator instruction: " << *TI;
abort();
}
}
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())) {
if (IV.isOverdefined()) { // PHI node becomes overdefined!
markOverdefined(PNIV, &PN);
// 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 (IV.getConstant() != OperandVal) {
// Yes there is. This means the PHI node is not constant.
void SCCPSolver::visitSelectInst(SelectInst &I) {
LatticeVal &CondValue = getValueState(I.getCondition());
- if (CondValue.isOverdefined())
+ if (CondValue.isUndefined())
+ return;
+ if (CondValue.isConstant()) {
+ if (ConstantBool *CondCB = dyn_cast<ConstantBool>(CondValue.getConstant())){
+ mergeInValue(&I, getValueState(CondCB->getValue() ? I.getTrueValue()
+ : I.getFalseValue()));
+ 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() &&
+ TVal.getConstant() == FVal.getConstant()) {
+ markConstant(&I, FVal.getConstant());
+ return;
+ }
+
+ if (TVal.isUndefined()) { // select ?, undef, X -> X.
+ mergeInValue(&I, FVal);
+ } else if (FVal.isUndefined()) { // select ?, X, undef -> X.
+ mergeInValue(&I, TVal);
+ } else {
markOverdefined(&I);
- else if (CondValue.isConstant()) {
- if (CondValue.getConstant() == ConstantBool::True) {
- LatticeVal &Val = getValueState(I.getTrueValue());
- if (Val.isOverdefined())
- markOverdefined(&I);
- else if (Val.isConstant())
- markConstant(&I, Val.getConstant());
- } else if (CondValue.getConstant() == ConstantBool::False) {
- LatticeVal &Val = getValueState(I.getFalseValue());
- if (Val.isOverdefined())
- markOverdefined(&I);
- else if (Val.isConstant())
- markConstant(&I, Val.getConstant());
- } else
- markOverdefined(&I);
}
}
}
}
+void SCCPSolver::visitExtractElementInst(ExtractElementInst &I) {
+ // FIXME : SCCP does not handle vectors properly.
+ markOverdefined(&I);
+ return;
+
+#if 0
+ LatticeVal &ValState = getValueState(I.getOperand(0));
+ LatticeVal &IdxState = getValueState(I.getOperand(1));
+
+ if (ValState.isOverdefined() || IdxState.isOverdefined())
+ markOverdefined(&I);
+ else if(ValState.isConstant() && IdxState.isConstant())
+ markConstant(&I, ConstantExpr::getExtractElement(ValState.getConstant(),
+ IdxState.getConstant()));
+#endif
+}
+
+void SCCPSolver::visitInsertElementInst(InsertElementInst &I) {
+ // FIXME : SCCP does not handle vectors properly.
+ markOverdefined(&I);
+ return;
+#if 0
+ LatticeVal &ValState = getValueState(I.getOperand(0));
+ LatticeVal &EltState = getValueState(I.getOperand(1));
+ LatticeVal &IdxState = getValueState(I.getOperand(2));
+
+ if (ValState.isOverdefined() || EltState.isOverdefined() ||
+ IdxState.isOverdefined())
+ markOverdefined(&I);
+ else if(ValState.isConstant() && EltState.isConstant() &&
+ IdxState.isConstant())
+ markConstant(&I, ConstantExpr::getInsertElement(ValState.getConstant(),
+ EltState.getConstant(),
+ IdxState.getConstant()));
+ else if (ValState.isUndefined() && EltState.isConstant() &&
+ IdxState.isConstant())
+ markConstant(&I, ConstantExpr::getInsertElement(UndefValue::get(I.getType()),
+ EltState.getConstant(),
+ IdxState.getConstant()));
+#endif
+}
+
+void SCCPSolver::visitShuffleVectorInst(ShuffleVectorInst &I) {
+ // FIXME : SCCP does not handle vectors properly.
+ markOverdefined(&I);
+ return;
+#if 0
+ LatticeVal &V1State = getValueState(I.getOperand(0));
+ LatticeVal &V2State = getValueState(I.getOperand(1));
+ LatticeVal &MaskState = getValueState(I.getOperand(2));
+
+ 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() ?
+ V1State.getConstant() : UndefValue::get(I.getType());
+ Constant *V2 = V2State.isConstant() ?
+ V2State.getConstant() : UndefValue::get(I.getType());
+ Constant *Mask = MaskState.isConstant() ?
+ MaskState.getConstant() : UndefValue::get(I.getOperand(2)->getType());
+ markConstant(&I, ConstantExpr::getShuffleVector(V1, V2, Mask));
+ }
+#endif
+}
+
// Handle getelementptr instructions... if all operands are constants then we
// can turn this into a getelementptr ConstantExpr.
//
Constant *Ptr = Operands[0];
Operands.erase(Operands.begin()); // Erase the pointer from idx list...
- markConstant(IV, &I, ConstantExpr::getGetElementPtr(Ptr, Operands));
-}
-
-/// GetGEPGlobalInitializer - Given a constant and a getelementptr constantexpr,
-/// return the constant value being addressed by the constant expression, or
-/// null if something is funny.
-///
-static Constant *GetGEPGlobalInitializer(Constant *C, ConstantExpr *CE) {
- if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
- return 0; // Do not allow stepping over the value!
-
- // Loop over all of the operands, tracking down which value we are
- // addressing...
- for (unsigned i = 2, e = CE->getNumOperands(); i != e; ++i)
- if (ConstantUInt *CU = dyn_cast<ConstantUInt>(CE->getOperand(i))) {
- ConstantStruct *CS = dyn_cast<ConstantStruct>(C);
- if (CS == 0) return 0;
- if (CU->getValue() >= CS->getNumOperands()) return 0;
- C = CS->getOperand((unsigned)CU->getValue());
- } else if (ConstantSInt *CS = dyn_cast<ConstantSInt>(CE->getOperand(i))) {
- ConstantArray *CA = dyn_cast<ConstantArray>(C);
- if (CA == 0) return 0;
- if ((uint64_t)CS->getValue() >= CA->getNumOperands()) return 0;
- C = CA->getOperand((unsigned)CS->getValue());
- } else
- return 0;
- return C;
+ markConstant(IV, &I, ConstantExpr::getGetElementPtr(Ptr, Operands));
}
void SCCPSolver::visitStoreInst(Instruction &SI) {
markConstant(IV, &I, Constant::getNullValue(I.getType()));
return;
}
-
+
// Transform load (constant global) into the value loaded.
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Ptr)) {
if (GV->isConstant()) {
// Transform load (constantexpr_GEP global, 0, ...) into the value loaded.
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
if (CE->getOpcode() == Instruction::GetElementPtr)
- if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
- if (GV->isConstant() && !GV->isExternal())
- if (Constant *V =
- GetGEPGlobalInitializer(GV->getInitializer(), CE)) {
- markConstant(IV, &I, V);
- return;
- }
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
+ if (GV->isConstant() && !GV->isExternal())
+ if (Constant *V =
+ ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE)) {
+ markConstant(IV, &I, V);
+ return;
+ }
}
// Otherwise we cannot say for certain what value this load will produce.
hash_map<Function*, LatticeVal>::iterator TFRVI =TrackedFunctionRetVals.end();
if (F && F->hasInternalLinkage())
TFRVI = TrackedFunctionRetVals.find(F);
-
+
if (TFRVI != TrackedFunctionRetVals.end()) {
// If this is the first call to the function hit, mark its entry block
// executable.
MarkBlockExecutable(F->begin());
CallSite::arg_iterator CAI = CS.arg_begin();
- for (Function::aiterator AI = F->abegin(), E = F->aend();
+ for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
AI != E; ++AI, ++CAI) {
LatticeVal &IV = ValueState[AI];
if (!IV.isOverdefined())
mergeInValue(IV, I, TFRVI->second);
return;
}
-
+
if (F == 0 || !F->isExternal() || !canConstantFoldCallTo(F)) {
markOverdefined(IV, I);
return;
void SCCPSolver::Solve() {
// Process the work lists until they are empty!
- while (!BBWorkList.empty() || !InstWorkList.empty() ||
- !OverdefinedInstWorkList.empty()) {
+ while (!BBWorkList.empty() || !InstWorkList.empty() ||
+ !OverdefinedInstWorkList.empty()) {
// Process the instruction work list...
while (!OverdefinedInstWorkList.empty()) {
Value *I = OverdefinedInstWorkList.back();
OverdefinedInstWorkList.pop_back();
- DEBUG(std::cerr << "\nPopped off OI-WL: " << *I);
-
+ DOUT << "\nPopped off OI-WL: " << *I;
+
// "I" got into the work list because it either made the transition from
// bottom to constant
//
Value *I = InstWorkList.back();
InstWorkList.pop_back();
- DEBUG(std::cerr << "\nPopped off I-WL: " << *I);
-
+ DOUT << "\nPopped off I-WL: " << *I;
+
// "I" got into the work list because it either made the transition from
// bottom to constant
//
UI != E; ++UI)
OperandChangedState(*UI);
}
-
+
// Process the basic block work list...
while (!BBWorkList.empty()) {
BasicBlock *BB = BBWorkList.back();
BBWorkList.pop_back();
-
- DEBUG(std::cerr << "\nPopped off BBWL: " << *BB);
-
+
+ DOUT << "\nPopped off BBWL: " << *BB;
+
// Notify all instructions in this basic block that they are newly
// executable.
visit(BB);
/// However, this is not a safe assumption. After we solve dataflow, this
/// method should be use to handle this. If this returns true, the solver
/// should be rerun.
+///
+/// This method handles this by finding an unresolved branch and marking it one
+/// of the edges from the block as being feasible, even though the condition
+/// doesn't say it would otherwise be. This allows SCCP to find the rest of the
+/// CFG and only slightly pessimizes the analysis results (by marking one,
+/// potentially unfeasible, edge feasible). This cannot usefully modify the
+/// constraints on the condition of the branch, as that would impact other users
+/// of the value.
bool SCCPSolver::ResolveBranchesIn(Function &F) {
- bool BranchesResolved = false;
- for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
- if (BBExecutable.count(BB)) {
- TerminatorInst *TI = BB->getTerminator();
- if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
- if (BI->isConditional()) {
- LatticeVal &BCValue = getValueState(BI->getCondition());
- if (BCValue.isUndefined()) {
- BI->setCondition(ConstantBool::True);
- BranchesResolved = true;
- visit(BI);
- }
- }
- } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
- LatticeVal &SCValue = getValueState(SI->getCondition());
- if (SCValue.isUndefined()) {
- const Type *CondTy = SI->getCondition()->getType();
- SI->setCondition(Constant::getNullValue(CondTy));
- BranchesResolved = true;
- visit(SI);
- }
- }
+ for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
+ if (!BBExecutable.count(BB))
+ continue;
+
+ 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 (!getValueState(SI->getCondition()).isUndefined())
+ continue;
+ } else {
+ continue;
}
+
+ // If the edge to the first successor isn't thought to be feasible yet, mark
+ // it so now.
+ if (KnownFeasibleEdges.count(Edge(BB, TI->getSuccessor(0))))
+ 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(0));
+ return true;
+ }
- return BranchesResolved;
+ return false;
}
namespace {
- Statistic<> NumInstRemoved("sccp", "Number of instructions removed");
- Statistic<> NumDeadBlocks ("sccp", "Number of basic blocks unreachable");
+ Statistic NumInstRemoved("sccp", "Number of instructions removed");
+ Statistic NumDeadBlocks ("sccp", "Number of basic blocks unreachable");
//===--------------------------------------------------------------------===//
//
// algorithm, and return true if the function was modified.
//
bool runOnFunction(Function &F);
-
+
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
}
};
- RegisterOpt<SCCP> X("sccp", "Sparse Conditional Constant Propagation");
+ RegisterPass<SCCP> X("sccp", "Sparse Conditional Constant Propagation");
} // end anonymous namespace
// and return true if the function was modified.
//
bool SCCP::runOnFunction(Function &F) {
- DEBUG(std::cerr << "SCCP on function '" << F.getName() << "'\n");
+ DOUT << "SCCP on function '" << F.getName() << "'\n";
SCCPSolver Solver;
// Mark the first block of the function as being executable.
// Mark all arguments to the function as being overdefined.
hash_map<Value*, LatticeVal> &Values = Solver.getValueMapping();
- for (Function::aiterator AI = F.abegin(), E = F.aend(); AI != E; ++AI)
+ for (Function::arg_iterator AI = F.arg_begin(), E = F.arg_end(); AI != E; ++AI)
Values[AI].markOverdefined();
// Solve for constants.
bool ResolvedBranches = true;
while (ResolvedBranches) {
Solver.Solve();
- DEBUG(std::cerr << "RESOLVING UNDEF BRANCHES\n");
+ DOUT << "RESOLVING UNDEF BRANCHES\n";
ResolvedBranches = Solver.ResolveBranchesIn(F);
}
std::set<BasicBlock*> &ExecutableBBs = Solver.getExecutableBlocks();
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
if (!ExecutableBBs.count(BB)) {
- DEBUG(std::cerr << " BasicBlock Dead:" << *BB);
+ DOUT << " BasicBlock Dead:" << *BB;
++NumDeadBlocks;
// Delete the instructions backwards, as it has a reduced likelihood of
!isa<TerminatorInst>(Inst)) {
Constant *Const = IV.isConstant()
? IV.getConstant() : UndefValue::get(Inst->getType());
- DEBUG(std::cerr << " Constant: " << *Const << " = " << *Inst);
-
+ DOUT << " Constant: " << *Const << " = " << *Inst;
+
// Replaces all of the uses of a variable with uses of the constant.
Inst->replaceAllUsesWith(Const);
-
+
// Delete the instruction.
BB->getInstList().erase(Inst);
-
+
// Hey, we just changed something!
MadeChanges = true;
++NumInstRemoved;
}
namespace {
- Statistic<> IPNumInstRemoved("ipsccp", "Number of instructions removed");
- Statistic<> IPNumDeadBlocks ("ipsccp", "Number of basic blocks unreachable");
- Statistic<> IPNumArgsElimed ("ipsccp",
+ Statistic IPNumInstRemoved("ipsccp", "Number of instructions removed");
+ Statistic IPNumDeadBlocks ("ipsccp", "Number of basic blocks unreachable");
+ Statistic IPNumArgsElimed ("ipsccp",
"Number of arguments constant propagated");
- Statistic<> IPNumGlobalConst("ipsccp",
+ Statistic IPNumGlobalConst("ipsccp",
"Number of globals found to be constant");
//===--------------------------------------------------------------------===//
bool runOnModule(Module &M);
};
- RegisterOpt<IPSCCP>
+ RegisterPass<IPSCCP>
Y("ipsccp", "Interprocedural Sparse Conditional Constant Propagation");
} // end anonymous namespace
static bool AddressIsTaken(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)) {
if (!F->hasInternalLinkage() || AddressIsTaken(F)) {
if (!F->isExternal())
Solver.MarkBlockExecutable(F->begin());
- for (Function::aiterator AI = F->abegin(), E = F->aend(); AI != E; ++AI)
+ for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
+ AI != E; ++AI)
Values[AI].markOverdefined();
} else {
Solver.AddTrackedFunction(F);
// 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::giterator G = M.gbegin(), E = M.gend(); G != E; ++G)
+ for (Module::global_iterator G = M.global_begin(), E = M.global_end();
+ G != E; ++G)
if (!G->isConstant() && G->hasInternalLinkage() && !AddressIsTaken(G))
Solver.TrackValueOfGlobalVariable(G);
while (ResolvedBranches) {
Solver.Solve();
- DEBUG(std::cerr << "RESOLVING UNDEF BRANCHES\n");
+ DOUT << "RESOLVING UNDEF BRANCHES\n";
ResolvedBranches = false;
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F)
ResolvedBranches |= Solver.ResolveBranchesIn(*F);
//
std::set<BasicBlock*> &ExecutableBBs = Solver.getExecutableBlocks();
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
- for (Function::aiterator AI = F->abegin(), E = F->aend(); AI != E; ++AI)
+ for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
+ AI != E; ++AI)
if (!AI->use_empty()) {
LatticeVal &IV = Values[AI];
if (IV.isConstant() || IV.isUndefined()) {
Constant *CST = IV.isConstant() ?
IV.getConstant() : UndefValue::get(AI->getType());
- DEBUG(std::cerr << "*** Arg " << *AI << " = " << *CST <<"\n");
-
+ DOUT << "*** Arg " << *AI << " = " << *CST <<"\n";
+
// Replaces all of the uses of a variable with uses of the
// constant.
AI->replaceAllUsesWith(CST);
std::vector<BasicBlock*> BlocksToErase;
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
if (!ExecutableBBs.count(BB)) {
- DEBUG(std::cerr << " BasicBlock Dead:" << *BB);
+ DOUT << " BasicBlock Dead:" << *BB;
++IPNumDeadBlocks;
// Delete the instructions backwards, as it has a reduced likelihood of
MadeChanges = true;
++IPNumInstRemoved;
}
-
+
for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) {
BasicBlock *Succ = TI->getSuccessor(i);
if (Succ->begin() != Succ->end() && isa<PHINode>(Succ->begin()))
!isa<TerminatorInst>(Inst)) {
Constant *Const = IV.isConstant()
? IV.getConstant() : UndefValue::get(Inst->getType());
- DEBUG(std::cerr << " Constant: " << *Const << " = " << *Inst);
-
+ DOUT << " Constant: " << *Const << " = " << *Inst;
+
// Replaces all of the uses of a variable with uses of the
// constant.
Inst->replaceAllUsesWith(Const);
-
+
// Delete the instruction.
if (!isa<TerminatorInst>(Inst) && !isa<CallInst>(Inst))
BB->getInstList().erase(Inst);
while (!DeadBB->use_empty()) {
Instruction *I = cast<Instruction>(DeadBB->use_back());
bool Folded = ConstantFoldTerminator(I->getParent());
- assert(Folded && "Didn't fold away reference to block!");
+ if (!Folded) {
+ // The constant folder may not have been able to fold the termiantor
+ // if this is a branch or switch on undef. Fold it manually as a
+ // branch to the first successor.
+ if (BranchInst *BI = dyn_cast<BranchInst>(I)) {
+ assert(BI->isConditional() && isa<UndefValue>(BI->getCondition()) &&
+ "Branch should be foldable!");
+ } else if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
+ assert(isa<UndefValue>(SI->getCondition()) && "Switch should fold");
+ } else {
+ assert(0 && "Didn't fold away reference to block!");
+ }
+
+ // Make this an uncond branch to the first successor.
+ TerminatorInst *TI = I->getParent()->getTerminator();
+ new BranchInst(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();
+ }
}
-
+
// Finally, delete the basic block.
F->getBasicBlockList().erase(DeadBB);
}
GlobalVariable *GV = I->first;
assert(!I->second.isOverdefined() &&
"Overdefined values should have been taken out of the map!");
- DEBUG(std::cerr << "Found that GV '" << GV->getName()<< "' is constant!\n");
+ DOUT << "Found that GV '" << GV->getName()<< "' is constant!\n";
while (!GV->use_empty()) {
StoreInst *SI = cast<StoreInst>(GV->use_back());
SI->eraseFromParent();
M.getGlobalList().erase(GV);
++IPNumGlobalConst;
}
-
+
return MadeChanges;
}
projects / oota-llvm.git / blobdiff