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switch the main 'ValueState' map from being an std::map to being

Browse Source 
a DenseMap.  Doing this required being aware of subtle iterator
invalidation issues, but it provides a big speedup.  In a 
release-asserts build, this sped up optimizing 403.gcc from
1.34s -> 0.79s (IPSCCP) and 1.11s -> 0.44s (SCCP).

This commit also conflates in a bunch of general cleanups, sorry.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85788 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2009-11-02 05:55:40 +00:00
parent 7baae87d8f
commit 2a0433beea
1 changed files with 280 additions and 310 deletions
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590
lib/Transforms/Scalar/SCCP.cpp
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@ -155,7 +155,7 @@ namespace {
///
class SCCPSolver : public InstVisitor<SCCPSolver> {
DenseSet<BasicBlock*> BBExecutable;// The basic blocks that are executable
std::map<Value*, LatticeVal> ValueState; // The state each value is in.
DenseMap<Value*, LatticeVal> ValueState; // The state each value is in.
/// 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
@ -246,7 +246,7 @@ public:
}
LatticeVal getLatticeValueFor(Value *V) const {
std::map<Value*, LatticeVal>::const_iterator I = ValueState.find(V);
DenseMap<Value*, LatticeVal>::const_iterator I = ValueState.find(V);
assert(I != ValueState.end() && "V is not in valuemap!");
return I->second;
}
@ -278,16 +278,17 @@ private:
InstWorkList.push_back(V);
}
void markForcedConstant(LatticeVal &IV, Value *V, Constant *C) {
IV.markForcedConstant(C);
DEBUG(errs() << "markForcedConstant: " << *C << ": " << *V << '\n');
InstWorkList.push_back(V);
}
void markConstant(Value *V, Constant *C) {
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);
}
// 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.
@ -303,7 +304,7 @@ private:
OverdefinedInstWorkList.push_back(V);
}
void mergeInValue(LatticeVal &IV, Value *V, LatticeVal &MergeWithV) {
void mergeInValue(LatticeVal &IV, Value *V, LatticeVal MergeWithV) {
if (IV.isOverdefined() || MergeWithV.isUndefined())
return; // Noop.
if (MergeWithV.isOverdefined())
@ -314,19 +315,16 @@ private:
markOverdefined(IV, V);
}
void mergeInValue(Value *V, LatticeVal &MergeWithV) {
void mergeInValue(Value *V, LatticeVal MergeWithV) {
mergeInValue(ValueState[V], V, MergeWithV);
}
// getValueState - Return the LatticeVal object that corresponds to the value.
// This function is necessary because not all values should start out in the
// underdefined state. Argument's should be overdefined, and
// constants should be marked as constants. If a value is not known to be an
// Instruction object, then use this accessor to get its value from the map.
//
/// getValueState - Return the LatticeVal object that corresponds to the
/// value. This function handles the case when the value hasn't been seen yet
/// by properly seeding constants etc.
LatticeVal &getValueState(Value *V) {
std::map<Value*, LatticeVal>::iterator I = ValueState.find(V);
DenseMap<Value*, LatticeVal>::iterator I = ValueState.find(V);
if (I != ValueState.end()) return I->second; // Common case, in the map
LatticeVal &LV = ValueState[V];
@ -341,9 +339,8 @@ private:
return LV;
}
// markEdgeExecutable - Mark a basic block as executable, adding it to the BB
// work list if it is not already executable.
//
/// 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!
@ -407,7 +404,7 @@ private:
void visitInsertValueInst(InsertValueInst &IVI);
// Instructions that cannot be folded away.
void visitStoreInst (Instruction &I);
void visitStoreInst (StoreInst &I);
void visitLoadInst (LoadInst &I);
void visitGetElementPtrInst(GetElementPtrInst &I);
void visitCallInst (CallInst &I) {
@ -448,7 +445,7 @@ void SCCPSolver::getFeasibleSuccessors(TerminatorInst &TI,
return;
}
LatticeVal &BCValue = getValueState(BI->getCondition());
LatticeVal BCValue = getValueState(BI->getCondition());
ConstantInt *CI = BCValue.getConstantInt();
if (CI == 0) {
// Overdefined condition variables, and branches on unfoldable constant
@ -470,7 +467,7 @@ void SCCPSolver::getFeasibleSuccessors(TerminatorInst &TI,
}
if (SwitchInst *SI = dyn_cast<SwitchInst>(&TI)) {
LatticeVal &SCValue = getValueState(SI->getCondition());
LatticeVal SCValue = getValueState(SI->getCondition());
ConstantInt *CI = SCValue.getConstantInt();
if (CI == 0) { // Overdefined or undefined condition?
@ -513,7 +510,7 @@ bool SCCPSolver::isEdgeFeasible(BasicBlock *From, BasicBlock *To) {
if (BI->isUnconditional())
return true;
LatticeVal &BCValue = getValueState(BI->getCondition());
LatticeVal BCValue = getValueState(BI->getCondition());
// Overdefined condition variables mean the branch could go either way,
// undef conditions mean that neither edge is feasible yet.
@ -530,7 +527,7 @@ bool SCCPSolver::isEdgeFeasible(BasicBlock *From, BasicBlock *To) {
return true;
if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
LatticeVal &SCValue = getValueState(SI->getCondition());
LatticeVal SCValue = getValueState(SI->getCondition());
ConstantInt *CI = SCValue.getConstantInt();
if (CI == 0)
@ -576,28 +573,27 @@ bool SCCPSolver::isEdgeFeasible(BasicBlock *From, BasicBlock *To) {
// successors executable.
//
void SCCPSolver::visitPHINode(PHINode &PN) {
LatticeVal &PNIV = getValueState(&PN);
if (PNIV.isOverdefined()) {
if (getValueState(&PN).isOverdefined()) {
// There may be instructions using this PHI node that are not overdefined
// themselves. If so, make sure that they know that the PHI node operand
// changed.
std::multimap<PHINode*, Instruction*>::iterator I, E;
tie(I, E) = UsersOfOverdefinedPHIs.equal_range(&PN);
if (I != E) {
SmallVector<Instruction*, 16> Users;
for (; I != E; ++I) Users.push_back(I->second);
while (!Users.empty()) {
visit(Users.back());
Users.pop_back();
}
}
if (I == E)
return;
SmallVector<Instruction*, 16> Users;
for (; I != E; ++I)
Users.push_back(I->second);
while (!Users.empty())
visit(Users.pop_back_val());
return; // Quick exit
}
// Super-extra-high-degree PHI nodes are unlikely to ever be marked constant,
// and slow us down a lot. Just mark them overdefined.
if (PN.getNumIncomingValues() > 64)
return markOverdefined(PNIV, &PN);
return markOverdefined(&PN);
// Look at all of the executable operands of the PHI node. If any of them
// are overdefined, the PHI becomes overdefined as well. If they are all
@ -607,7 +603,7 @@ void SCCPSolver::visitPHINode(PHINode &PN) {
//
Constant *OperandVal = 0;
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
LatticeVal &IV = getValueState(PN.getIncomingValue(i));
LatticeVal IV = getValueState(PN.getIncomingValue(i));
if (IV.isUndefined()) continue; // Doesn't influence PHI node.
if (!isEdgeFeasible(PN.getIncomingBlock(i), PN.getParent()))
@ -641,26 +637,25 @@ void SCCPSolver::visitPHINode(PHINode &PN) {
}
void SCCPSolver::visitReturnInst(ReturnInst &I) {
if (I.getNumOperands() == 0) return; // Ret void
if (I.getNumOperands() == 0) return; // ret void
Function *F = I.getParent()->getParent();
// If we are tracking the return value of this function, merge it in.
if (!F->hasLocalLinkage())
return;
if (!TrackedRetVals.empty() && I.getNumOperands() == 1) {
if (!TrackedRetVals.empty()) {
DenseMap<Function*, LatticeVal>::iterator TFRVI =
TrackedRetVals.find(F);
if (TFRVI != TrackedRetVals.end() &&
!TFRVI->second.isOverdefined()) {
LatticeVal &IV = getValueState(I.getOperand(0));
mergeInValue(TFRVI->second, F, IV);
mergeInValue(TFRVI->second, F, getValueState(I.getOperand(0)));
return;
}
}
// Handle functions that return multiple values.
if (!TrackedMultipleRetVals.empty() && I.getNumOperands() > 1) {
if (0 && !TrackedMultipleRetVals.empty() && I.getNumOperands() > 1) {
for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i) {
DenseMap<std::pair<Function*, unsigned>, LatticeVal>::iterator
It = TrackedMultipleRetVals.find(std::make_pair(F, i));
@ -668,7 +663,7 @@ void SCCPSolver::visitReturnInst(ReturnInst &I) {
mergeInValue(It->second, F, getValueState(I.getOperand(i)));
}
} else if (!TrackedMultipleRetVals.empty() &&
I.getNumOperands() == 1 &&
/*I.getNumOperands() == 1 &&*/
isa<StructType>(I.getOperand(0)->getType())) {
for (unsigned i = 0, e = I.getOperand(0)->getType()->getNumContainedTypes();
i != e; ++i) {
@ -694,13 +689,12 @@ void SCCPSolver::visitTerminatorInst(TerminatorInst &TI) {
}
void SCCPSolver::visitCastInst(CastInst &I) {
Value *V = I.getOperand(0);
LatticeVal &VState = getValueState(V);
if (VState.isOverdefined()) // Inherit overdefinedness of operand
LatticeVal OpSt = getValueState(I.getOperand(0));
if (OpSt.isOverdefined()) // Inherit overdefinedness of operand
markOverdefined(&I);
else if (VState.isConstant()) // Propagate constant value
else if (OpSt.isConstant()) // Propagate constant value
markConstant(&I, ConstantExpr::getCast(I.getOpcode(),
VState.getConstant(), I.getType()));
OpSt.getConstant(), I.getType()));
}
void SCCPSolver::visitExtractValueInst(ExtractValueInst &EVI) {
@ -775,246 +769,230 @@ void SCCPSolver::visitInsertValueInst(InsertValueInst &IVI) {
}
void SCCPSolver::visitSelectInst(SelectInst &I) {
LatticeVal &CondValue = getValueState(I.getCondition());
LatticeVal CondValue = getValueState(I.getCondition());
if (CondValue.isUndefined())
return;
if (ConstantInt *CondCB = CondValue.getConstantInt()) {
mergeInValue(&I, getValueState(CondCB->getZExtValue() ? I.getTrueValue()
: I.getFalseValue()));
Value *OpVal = CondCB->isZero() ? I.getFalseValue() : I.getTrueValue();
mergeInValue(&I, getValueState(OpVal));
return;
}
// Otherwise, the condition is overdefined or a constant we can't evaluate.
// See if we can produce something better than overdefined based on the T/F
// value.
LatticeVal &TVal = getValueState(I.getTrueValue());
LatticeVal &FVal = getValueState(I.getFalseValue());
LatticeVal TVal = getValueState(I.getTrueValue());
LatticeVal FVal = getValueState(I.getFalseValue());
// select ?, C, C -> C.
if (TVal.isConstant() && FVal.isConstant() &&
TVal.getConstant() == FVal.getConstant())
return markConstant(&I, FVal.getConstant());
if (TVal.isUndefined()) { // select ?, undef, X -> X.
mergeInValue(&I, FVal);
} else if (FVal.isUndefined()) { // select ?, X, undef -> X.
mergeInValue(&I, TVal);
} else {
markOverdefined(&I);
}
if (TVal.isUndefined()) // select ?, undef, X -> X.
return mergeInValue(&I, FVal);
if (FVal.isUndefined()) // select ?, X, undef -> X.
return mergeInValue(&I, TVal);
markOverdefined(&I);
}
// Handle BinaryOperators and Shift Instructions.
// Handle Binary Operators.
void SCCPSolver::visitBinaryOperator(Instruction &I) {
LatticeVal V1State = getValueState(I.getOperand(0));
LatticeVal V2State = getValueState(I.getOperand(1));
LatticeVal &IV = ValueState[&I];
if (IV.isOverdefined()) return;
LatticeVal &V1State = getValueState(I.getOperand(0));
LatticeVal &V2State = getValueState(I.getOperand(1));
if (V1State.isConstant() && V2State.isConstant())
return markConstant(IV, &I,
ConstantExpr::get(I.getOpcode(), V1State.getConstant(),
V2State.getConstant()));
// If something is undef, wait for it to resolve.
if (!V1State.isOverdefined() && !V2State.isOverdefined())
return;
// Otherwise, one of our operands is overdefined. Try to produce something
// better than overdefined with some tricks.
// If this is an AND or OR with 0 or -1, it doesn't matter that the other
// operand is overdefined.
if (I.getOpcode() == Instruction::And || I.getOpcode() == Instruction::Or) {
LatticeVal *NonOverdefVal = 0;
if (!V1State.isOverdefined())
NonOverdefVal = &V1State;
else if (!V2State.isOverdefined())
NonOverdefVal = &V2State;
if (V1State.isOverdefined() || V2State.isOverdefined()) {
// If this is an AND or OR with 0 or -1, it doesn't matter that the other
// operand is overdefined.
if (I.getOpcode() == Instruction::And || I.getOpcode() == Instruction::Or) {
LatticeVal *NonOverdefVal = 0;
if (!V1State.isOverdefined()) {
NonOverdefVal = &V1State;
} else if (!V2State.isOverdefined()) {
NonOverdefVal = &V2State;
if (NonOverdefVal) {
if (NonOverdefVal->isUndefined()) {
// Could annihilate value.
if (I.getOpcode() == Instruction::And)
markConstant(IV, &I, Constant::getNullValue(I.getType()));
else if (const VectorType *PT = dyn_cast<VectorType>(I.getType()))
markConstant(IV, &I, Constant::getAllOnesValue(PT));
else
markConstant(IV, &I,
Constant::getAllOnesValue(I.getType()));
return;
}
if (NonOverdefVal) {
if (NonOverdefVal->isUndefined()) {
// Could annihilate value.
if (I.getOpcode() == Instruction::And)
markConstant(IV, &I, Constant::getNullValue(I.getType()));
else if (const VectorType *PT = dyn_cast<VectorType>(I.getType()))
markConstant(IV, &I, Constant::getAllOnesValue(PT));
else
markConstant(IV, &I,
Constant::getAllOnesValue(I.getType()));
return;
} else {
if (I.getOpcode() == Instruction::And) {
// X and 0 = 0
if (NonOverdefVal->getConstant()->isNullValue())
return markConstant(IV, &I, NonOverdefVal->getConstant());
} else {
if (ConstantInt *CI = NonOverdefVal->getConstantInt())
if (CI->isAllOnesValue()) // X or -1 = -1
return markConstant(IV, &I, NonOverdefVal->getConstant());
}
}
if (I.getOpcode() == Instruction::And) {
// X and 0 = 0
if (NonOverdefVal->getConstant()->isNullValue())
return markConstant(IV, &I, NonOverdefVal->getConstant());
} else {
if (ConstantInt *CI = NonOverdefVal->getConstantInt())
if (CI->isAllOnesValue()) // X or -1 = -1
return markConstant(IV, &I, NonOverdefVal->getConstant());
}
}
}
// If both operands are PHI nodes, it is possible that this instruction has
// a constant value, despite the fact that the PHI node doesn't. Check for
// this condition now.
if (PHINode *PN1 = dyn_cast<PHINode>(I.getOperand(0)))
if (PHINode *PN2 = dyn_cast<PHINode>(I.getOperand(1)))
if (PN1->getParent() == PN2->getParent()) {
// Since the two PHI nodes are in the same basic block, they must have
// entries for the same predecessors. Walk the predecessor list, and
// if all of the incoming values are constants, and the result of
// evaluating this expression with all incoming value pairs is the
// same, then this expression is a constant even though the PHI node
// is not a constant!
LatticeVal Result;
for (unsigned i = 0, e = PN1->getNumIncomingValues(); i != e; ++i) {
LatticeVal &In1 = getValueState(PN1->getIncomingValue(i));
BasicBlock *InBlock = PN1->getIncomingBlock(i);
LatticeVal &In2 =
getValueState(PN2->getIncomingValueForBlock(InBlock));
// If both operands are PHI nodes, it is possible that this instruction has
// a constant value, despite the fact that the PHI node doesn't. Check for
// this condition now.
if (PHINode *PN1 = dyn_cast<PHINode>(I.getOperand(0)))
if (PHINode *PN2 = dyn_cast<PHINode>(I.getOperand(1)))
if (PN1->getParent() == PN2->getParent()) {
// Since the two PHI nodes are in the same basic block, they must have
// entries for the same predecessors. Walk the predecessor list, and
// if all of the incoming values are constants, and the result of
// evaluating this expression with all incoming value pairs is the
// same, then this expression is a constant even though the PHI node
// is not a constant!
LatticeVal Result;
for (unsigned i = 0, e = PN1->getNumIncomingValues(); i != e; ++i) {
LatticeVal In1 = getValueState(PN1->getIncomingValue(i));
BasicBlock *InBlock = PN1->getIncomingBlock(i);
LatticeVal In2 =getValueState(PN2->getIncomingValueForBlock(InBlock));
if (In1.isOverdefined() || In2.isOverdefined()) {
if (In1.isOverdefined() || In2.isOverdefined()) {
Result.markOverdefined();
break; // Cannot fold this operation over the PHI nodes!
}
if (In1.isConstant() && In2.isConstant()) {
Constant *V = ConstantExpr::get(I.getOpcode(), In1.getConstant(),
In2.getConstant());
if (Result.isUndefined())
Result.markConstant(V);
else if (Result.isConstant() && Result.getConstant() != V) {
Result.markOverdefined();
break; // Cannot fold this operation over the PHI nodes!
break;
}
if (In1.isConstant() && In2.isConstant()) {
Constant *V =
ConstantExpr::get(I.getOpcode(), In1.getConstant(),
In2.getConstant());
if (Result.isUndefined())
Result.markConstant(V);
else if (Result.isConstant() && Result.getConstant() != V) {
Result.markOverdefined();
break;
}
}
}
// If we found a constant value here, then we know the instruction is
// constant despite the fact that the PHI nodes are overdefined.
if (Result.isConstant()) {
markConstant(IV, &I, Result.getConstant());
// Remember that this instruction is virtually using the PHI node
// operands.
UsersOfOverdefinedPHIs.insert(std::make_pair(PN1, &I));
UsersOfOverdefinedPHIs.insert(std::make_pair(PN2, &I));
return;
} else if (Result.isUndefined()) {
return;
}
// Okay, this really is overdefined now. Since we might have
// speculatively thought that this was not overdefined before, and
// added ourselves to the UsersOfOverdefinedPHIs list for the PHIs,
// make sure to clean out any entries that we put there, for
// efficiency.
std::multimap<PHINode*, Instruction*>::iterator It, E;
tie(It, E) = UsersOfOverdefinedPHIs.equal_range(PN1);
while (It != E) {
if (It->second == &I) {
UsersOfOverdefinedPHIs.erase(It++);
} else
++It;
}
tie(It, E) = UsersOfOverdefinedPHIs.equal_range(PN2);
while (It != E) {
if (It->second == &I) {
UsersOfOverdefinedPHIs.erase(It++);
} else
++It;
}
}
markOverdefined(IV, &I);
} else if (V1State.isConstant() && V2State.isConstant()) {
markConstant(IV, &I,
ConstantExpr::get(I.getOpcode(), V1State.getConstant(),
V2State.getConstant()));
}
// 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.
UsersOfOverdefinedPHIs.erase(PN1);
UsersOfOverdefinedPHIs.erase(PN2);
}
markOverdefined(&I);
}
// Handle ICmpInst instruction.
void SCCPSolver::visitCmpInst(CmpInst &I) {
LatticeVal V1State = getValueState(I.getOperand(0));
LatticeVal V2State = getValueState(I.getOperand(1));
LatticeVal &IV = ValueState[&I];
if (IV.isOverdefined()) return;
LatticeVal &V1State = getValueState(I.getOperand(0));
LatticeVal &V2State = getValueState(I.getOperand(1));
if (V1State.isConstant() && V2State.isConstant())
return markConstant(IV, &I, ConstantExpr::getCompare(I.getPredicate(),
V1State.getConstant(),
V2State.getConstant()));
// If operands are still undefined, wait for it to resolve.
if (!V1State.isOverdefined() && !V2State.isOverdefined())
return;
// If something is overdefined, use some tricks to avoid ending up and over
// defined if we can.
// If both operands are PHI nodes, it is possible that this instruction has
// a constant value, despite the fact that the PHI node doesn't. Check for
// this condition now.
if (PHINode *PN1 = dyn_cast<PHINode>(I.getOperand(0)))
if (PHINode *PN2 = dyn_cast<PHINode>(I.getOperand(1)))
if (PN1->getParent() == PN2->getParent()) {
// Since the two PHI nodes are in the same basic block, they must have
// entries for the same predecessors. Walk the predecessor list, and
// if all of the incoming values are constants, and the result of
// evaluating this expression with all incoming value pairs is the
// same, then this expression is a constant even though the PHI node
// is not a constant!
LatticeVal Result;
for (unsigned i = 0, e = PN1->getNumIncomingValues(); i != e; ++i) {
LatticeVal In1 = getValueState(PN1->getIncomingValue(i));
BasicBlock *InBlock = PN1->getIncomingBlock(i);
LatticeVal In2 =getValueState(PN2->getIncomingValueForBlock(InBlock));
if (V1State.isOverdefined() || V2State.isOverdefined()) {
// If both operands are PHI nodes, it is possible that this instruction has
// a constant value, despite the fact that the PHI node doesn't. Check for
// this condition now.
if (PHINode *PN1 = dyn_cast<PHINode>(I.getOperand(0)))
if (PHINode *PN2 = dyn_cast<PHINode>(I.getOperand(1)))
if (PN1->getParent() == PN2->getParent()) {
// Since the two PHI nodes are in the same basic block, they must have
// entries for the same predecessors. Walk the predecessor list, and
// if all of the incoming values are constants, and the result of
// evaluating this expression with all incoming value pairs is the
// same, then this expression is a constant even though the PHI node
// is not a constant!
LatticeVal Result;
for (unsigned i = 0, e = PN1->getNumIncomingValues(); i != e; ++i) {
LatticeVal &In1 = getValueState(PN1->getIncomingValue(i));
BasicBlock *InBlock = PN1->getIncomingBlock(i);
LatticeVal &In2 =
getValueState(PN2->getIncomingValueForBlock(InBlock));
if (In1.isOverdefined() || In2.isOverdefined()) {
if (In1.isOverdefined() || In2.isOverdefined()) {
Result.markOverdefined();
break; // Cannot fold this operation over the PHI nodes!
}
if (In1.isConstant() && In2.isConstant()) {
Constant *V = ConstantExpr::getCompare(I.getPredicate(),
In1.getConstant(),
In2.getConstant());
if (Result.isUndefined())
Result.markConstant(V);
else if (Result.isConstant() && Result.getConstant() != V) {
Result.markOverdefined();
break; // Cannot fold this operation over the PHI nodes!
} else if (In1.isConstant() && In2.isConstant()) {
Constant *V = ConstantExpr::getCompare(I.getPredicate(),
In1.getConstant(),
In2.getConstant());
if (Result.isUndefined())
Result.markConstant(V);
else if (Result.isConstant() && Result.getConstant() != V) {
Result.markOverdefined();
break;
}
break;
}
}
// If we found a constant value here, then we know the instruction is
// constant despite the fact that the PHI nodes are overdefined.
if (Result.isConstant()) {
markConstant(IV, &I, Result.getConstant());
// Remember that this instruction is virtually using the PHI node
// operands.
UsersOfOverdefinedPHIs.insert(std::make_pair(PN1, &I));
UsersOfOverdefinedPHIs.insert(std::make_pair(PN2, &I));
return;
} else if (Result.isUndefined()) {
return;
}
// Okay, this really is overdefined now. Since we might have
// speculatively thought that this was not overdefined before, and
// added ourselves to the UsersOfOverdefinedPHIs list for the PHIs,
// make sure to clean out any entries that we put there, for
// efficiency.
std::multimap<PHINode*, Instruction*>::iterator It, E;
tie(It, E) = UsersOfOverdefinedPHIs.equal_range(PN1);
while (It != E) {
if (It->second == &I) {
UsersOfOverdefinedPHIs.erase(It++);
} else
++It;
}
tie(It, E) = UsersOfOverdefinedPHIs.equal_range(PN2);
while (It != E) {
if (It->second == &I) {
UsersOfOverdefinedPHIs.erase(It++);
} else
++It;
}
}
markOverdefined(IV, &I);
} else if (V1State.isConstant() && V2State.isConstant()) {
markConstant(IV, &I, ConstantExpr::getCompare(I.getPredicate(),
V1State.getConstant(),
V2State.getConstant()));
}
// 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.
UsersOfOverdefinedPHIs.erase(PN1);
UsersOfOverdefinedPHIs.erase(PN2);
}
markOverdefined(&I);
}
void SCCPSolver::visitExtractElementInst(ExtractElementInst &I) {
@ -1096,7 +1074,7 @@ void SCCPSolver::visitGetElementPtrInst(GetElementPtrInst &I) {
Operands.reserve(I.getNumOperands());
for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i) {
LatticeVal &State = getValueState(I.getOperand(i));
LatticeVal State = getValueState(I.getOperand(i));
if (State.isUndefined())
return; // Operands are not resolved yet.
@ -1108,23 +1086,20 @@ void SCCPSolver::visitGetElementPtrInst(GetElementPtrInst &I) {
}
Constant *Ptr = Operands[0];
Operands.erase(Operands.begin()); // Erase the pointer from idx list.
markConstant(IV, &I, ConstantExpr::getGetElementPtr(Ptr, &Operands[0],
Operands.size()));
markConstant(&I, ConstantExpr::getGetElementPtr(Ptr, &Operands[0]+1,
Operands.size()-1));
}
void SCCPSolver::visitStoreInst(Instruction &SI) {
void SCCPSolver::visitStoreInst(StoreInst &SI) {
if (TrackedGlobals.empty() || !isa<GlobalVariable>(SI.getOperand(1)))
return;
GlobalVariable *GV = cast<GlobalVariable>(SI.getOperand(1));
DenseMap<GlobalVariable*, LatticeVal>::iterator I = TrackedGlobals.find(GV);
if (I == TrackedGlobals.end() || I->second.isOverdefined()) return;
// Get the value we are storing into the global.
LatticeVal &PtrVal = getValueState(SI.getOperand(0));
mergeInValue(I->second, GV, PtrVal);
// Get the value we are storing into the global, then merge it.
mergeInValue(I->second, GV, getValueState(SI.getOperand(0)));
if (I->second.isOverdefined())
TrackedGlobals.erase(I); // No need to keep tracking this!
}
@ -1133,46 +1108,48 @@ void SCCPSolver::visitStoreInst(Instruction &SI) {
// 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) {
LatticeVal PtrVal = getValueState(I.getOperand(0));
LatticeVal &IV = ValueState[&I];
if (IV.isOverdefined()) return;
LatticeVal &PtrVal = getValueState(I.getOperand(0));
if (PtrVal.isUndefined()) return; // The pointer is not resolved yet!
if (PtrVal.isConstant() && !I.isVolatile()) {
Value *Ptr = PtrVal.getConstant();
// TODO: Consider a target hook for valid address spaces for this xform.
if (isa<ConstantPointerNull>(Ptr) && I.getPointerAddressSpace() == 0) {
// load null -> null
return markConstant(IV, &I, Constant::getNullValue(I.getType()));
}
if (!PtrVal.isConstant() || I.isVolatile())
return markOverdefined(IV, &I);
Value *Ptr = PtrVal.getConstant();
// Transform load (constant global) into the value loaded.
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Ptr)) {
if (GV->isConstant()) {
if (GV->hasDefinitiveInitializer())
return markConstant(IV, &I, GV->getInitializer());
} else if (!TrackedGlobals.empty()) {
// If we are tracking this global, merge in the known value for it.
DenseMap<GlobalVariable*, LatticeVal>::iterator It =
TrackedGlobals.find(GV);
if (It != TrackedGlobals.end()) {
mergeInValue(IV, &I, It->second);
return;
}
// load null -> null
if (isa<ConstantPointerNull>(Ptr) && I.getPointerAddressSpace() == 0)
return markConstant(IV, &I, Constant::getNullValue(I.getType()));
// Transform load (constant global) into the value loaded.
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Ptr)) {
if (GV->isConstant()) {
if (GV->hasDefinitiveInitializer())
return markConstant(IV, &I, GV->getInitializer());
} else if (!TrackedGlobals.empty()) {
// If we are tracking this global, merge in the known value for it.
DenseMap<GlobalVariable*, LatticeVal>::iterator It =
TrackedGlobals.find(GV);
if (It != TrackedGlobals.end()) {
mergeInValue(IV, &I, It->second);
return;
}
}
// Transform load (constantexpr_GEP global, 0, ...) into the value loaded.
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
if (CE->getOpcode() == Instruction::GetElementPtr)
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
if (GV->isConstant() && GV->hasDefinitiveInitializer())
if (Constant *V =
ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
return markConstant(IV, &I, V);
}
// Transform load (constantexpr_GEP global, 0, ...) into the value loaded.
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
if (CE->getOpcode() == Instruction::GetElementPtr)
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
if (GV->isConstant() && GV->hasDefinitiveInitializer())
if (Constant *V =
ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
return markConstant(IV, &I, V);
// Otherwise we cannot say for certain what value this load will produce.
// Bail out.
markOverdefined(IV, &I);
@ -1198,7 +1175,7 @@ CallOverdefined:
SmallVector<Constant*, 8> Operands;
for (CallSite::arg_iterator AI = CS.arg_begin(), E = CS.arg_end();
AI != E; ++AI) {
LatticeVal &State = getValueState(*AI);
LatticeVal State = getValueState(*AI);
if (State.isUndefined())
return; // Operands are not resolved yet.
@ -1266,13 +1243,12 @@ CallOverdefined:
CallSite::arg_iterator CAI = CS.arg_begin();
for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
AI != E; ++AI, ++CAI) {
LatticeVal &IV = ValueState[AI];
if (AI->hasByValAttr() && !F->onlyReadsMemory()) {
IV.markOverdefined();
markOverdefined(AI);
continue;
}
if (!IV.isOverdefined())
mergeInValue(IV, AI, getValueState(*CAI));
mergeInValue(AI, getValueState(*CAI));
}
}
@ -1280,10 +1256,10 @@ void SCCPSolver::Solve() {
// Process the work lists until they are empty!
while (!BBWorkList.empty() || !InstWorkList.empty() ||
!OverdefinedInstWorkList.empty()) {
// Process the instruction work list.
// Process the overdefined instruction's work list first, which drives other
// things to overdefined more quickly.
while (!OverdefinedInstWorkList.empty()) {
Value *I = OverdefinedInstWorkList.back();
OverdefinedInstWorkList.pop_back();
Value *I = OverdefinedInstWorkList.pop_back_val();
DEBUG(errs() << "\nPopped off OI-WL: " << *I << '\n');
@ -1301,13 +1277,12 @@ void SCCPSolver::Solve() {
// Process the instruction work list.
while (!InstWorkList.empty()) {
Value *I = InstWorkList.back();
InstWorkList.pop_back();
Value *I = InstWorkList.pop_back_val();
DEBUG(errs() << "\nPopped off I-WL: " << *I << '\n');
// "I" got into the work list because it either made the transition from
// bottom to constant
// "I" got into the work list because it made the transition from undef to
// constant.
//
// Anything on this worklist that is overdefined need not be visited
// since all of its users will have already been marked as overdefined.
@ -1364,7 +1339,7 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
if (!LV.isUndefined()) continue;
// Get the lattice values of the first two operands for use below.
LatticeVal &Op0LV = getValueState(I->getOperand(0));
LatticeVal Op0LV = getValueState(I->getOperand(0));
LatticeVal Op1LV;
if (I->getNumOperands() == 2) {
// If this is a two-operand instruction, and if both operands are
@ -1383,23 +1358,18 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
// After a zero extend, we know the top part is zero. SExt doesn't have
// to be handled here, because we don't know whether the top part is 1's
// or 0's.
assert(Op0LV.isUndefined());
markForcedConstant(LV, I, Constant::getNullValue(ITy));
markForcedConstant(I, Constant::getNullValue(ITy));
return true;
case Instruction::Mul:
case Instruction::And:
// undef * X -> 0. X could be zero.
// undef & X -> 0. X could be zero.
markForcedConstant(LV, I, Constant::getNullValue(ITy));
markForcedConstant(I, Constant::getNullValue(ITy));
return true;
case Instruction::Or:
// undef | X -> -1. X could be -1.
if (const VectorType *PTy = dyn_cast<VectorType>(ITy))
markForcedConstant(LV, I,
Constant::getAllOnesValue(PTy));
else
markForcedConstant(LV, I, Constant::getAllOnesValue(ITy));
markForcedConstant(I, Constant::getAllOnesValue(ITy));
return true;
case Instruction::SDiv:
@ -1412,7 +1382,7 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
// undef / X -> 0. X could be maxint.
// undef % X -> 0. X could be 1.
markForcedConstant(LV, I, Constant::getNullValue(ITy));
markForcedConstant(I, Constant::getNullValue(ITy));
return true;
case Instruction::AShr:
@ -1421,9 +1391,9 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
// X >>s undef -> X. X could be 0, X could have the high-bit known set.
if (Op0LV.isConstant())
markForcedConstant(LV, I, Op0LV.getConstant());
markForcedConstant(I, Op0LV.getConstant());
else
markOverdefined(LV, I);
markOverdefined(I);
return true;
case Instruction::LShr:
case Instruction::Shl:
@ -1433,7 +1403,7 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
// X >> undef -> 0. X could be 0.
// X << undef -> 0. X could be 0.
markForcedConstant(LV, I, Constant::getNullValue(ITy));
markForcedConstant(I, Constant::getNullValue(ITy));
return true;
case Instruction::Select:
// undef ? X : Y -> X or Y. There could be commonality between X/Y.
@ -1451,15 +1421,15 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
}
if (Op1LV.isConstant())
markForcedConstant(LV, I, Op1LV.getConstant());
markForcedConstant(I, Op1LV.getConstant());
else
markOverdefined(LV, I);
markOverdefined(I);
return true;
case Instruction::Call:
// If a call has an undef result, it is because it is constant foldable
// but one of the inputs was undef. Just force the result to
// overdefined.
markOverdefined(LV, I);
markOverdefined(I);
return true;
}
}