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[SCCP] Rename undefined -> unknown. 

In the solver, isUndefined() does really mean "we don't know the
value yet" rather than "this is an UndefinedValue". Discussed with
Eli Friedman.

Differential Revision:  http://reviews.llvm.org/D22192

llvm-svn: 275004
This commit is contained in:
Davide Italiano 2016-07-10 00:35:15 +00:00
parent 89c3762a7a
commit 0f03ce0c88
1 changed files with 40 additions and 40 deletions
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80
llvm/lib/Transforms/Scalar/SCCP.cpp
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@ -59,8 +59,8 @@ namespace {
///
class LatticeVal {
enum LatticeValueTy {
/// undefined - This LLVM Value has no known value yet.
undefined,
/// unknown - This LLVM Value has no known value yet.
unknown,
/// constant - This LLVM Value has a specific constant value.
constant,
@ -85,9 +85,9 @@ class LatticeVal {
}
public:
LatticeVal() : Val(nullptr, undefined) {}
LatticeVal() : Val(nullptr, unknown) {}
bool isUndefined() const { return getLatticeValue() == undefined; }
bool isUnknown() const { return getLatticeValue() == unknown; }
bool isConstant() const {
return getLatticeValue() == constant || getLatticeValue() == forcedconstant;
}
@ -114,7 +114,7 @@ public:
return false;
}
if (isUndefined()) {
if (isUnknown()) {
Val.setInt(constant);
assert(V && "Marking constant with NULL");
Val.setPointer(V);
@ -141,7 +141,7 @@ public:
}
void markForcedConstant(Constant *V) {
assert(isUndefined() && "Can't force a defined value!");
assert(isUnknown() && "Can't force a defined value!");
Val.setInt(forcedconstant);
Val.setPointer(V);
}
@ -350,11 +350,11 @@ private:
}
void mergeInValue(LatticeVal &IV, Value *V, LatticeVal MergeWithV) {
if (IV.isOverdefined() || MergeWithV.isUndefined())
if (IV.isOverdefined() || MergeWithV.isUnknown())
return; // Noop.
if (MergeWithV.isOverdefined())
markOverdefined(IV, V);
else if (IV.isUndefined())
else if (IV.isUnknown())
markConstant(IV, V, MergeWithV.getConstant());
else if (IV.getConstant() != MergeWithV.getConstant())
markOverdefined(IV, V);
@ -380,7 +380,7 @@ private:
return LV; // Common case, already in the map.
if (Constant *C = dyn_cast<Constant>(V)) {
// Undef values remain undefined.
// Undef values remain unknown.
if (!isa<UndefValue>(V))
LV.markConstant(C); // Constants are constant
}
@ -411,7 +411,7 @@ private:
if (!Elt)
LV.markOverdefined(); // Unknown sort of constant.
else if (isa<UndefValue>(Elt))
; // Undef values remain undefined.
; // Undef values remain unknown.
else
LV.markConstant(Elt); // Constants are constant.
}
@ -539,7 +539,7 @@ void SCCPSolver::getFeasibleSuccessors(TerminatorInst &TI,
if (!CI) {
// Overdefined condition variables, and branches on unfoldable constant
// conditions, mean the branch could go either way.
if (!BCValue.isUndefined())
if (!BCValue.isUnknown())
Succs[0] = Succs[1] = true;
return;
}
@ -563,9 +563,9 @@ void SCCPSolver::getFeasibleSuccessors(TerminatorInst &TI,
LatticeVal SCValue = getValueState(SI->getCondition());
ConstantInt *CI = SCValue.getConstantInt();
if (!CI) { // Overdefined or undefined condition?
if (!CI) { // Overdefined or unknown condition?
// All destinations are executable!
if (!SCValue.isUndefined())
if (!SCValue.isUnknown())
Succs.assign(TI.getNumSuccessors(), true);
return;
}
@ -609,7 +609,7 @@ bool SCCPSolver::isEdgeFeasible(BasicBlock *From, BasicBlock *To) {
// undef conditions mean that neither edge is feasible yet.
ConstantInt *CI = BCValue.getConstantInt();
if (!CI)
return !BCValue.isUndefined();
return !BCValue.isUnknown();
// Constant condition variables mean the branch can only go a single way.
return BI->getSuccessor(CI->isZero()) == To;
@ -627,7 +627,7 @@ bool SCCPSolver::isEdgeFeasible(BasicBlock *From, BasicBlock *To) {
ConstantInt *CI = SCValue.getConstantInt();
if (!CI)
return !SCValue.isUndefined();
return !SCValue.isUnknown();
return SI->findCaseValue(CI).getCaseSuccessor() == To;
}
@ -679,12 +679,12 @@ void SCCPSolver::visitPHINode(PHINode &PN) {
// 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.
// If there are no executable operands, the PHI remains unknown.
//
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 (IV.isUnknown()) continue; // Doesn't influence PHI node.
if (!isEdgeFeasible(PN.getIncomingBlock(i), PN.getParent()))
continue;
@ -710,7 +710,7 @@ void SCCPSolver::visitPHINode(PHINode &PN) {
// If we exited the loop, this means that the PHI node only has constant
// arguments that agree with each other(and OperandVal is the constant) or
// OperandVal is null because there are no defined incoming arguments. If
// this is the case, the PHI remains undefined.
// this is the case, the PHI remains unknown.
//
if (OperandVal)
markConstant(&PN, OperandVal); // Acquire operand value
@ -833,7 +833,7 @@ void SCCPSolver::visitSelectInst(SelectInst &I) {
return markAnythingOverdefined(&I);
LatticeVal CondValue = getValueState(I.getCondition());
if (CondValue.isUndefined())
if (CondValue.isUnknown())
return;
if (ConstantInt *CondCB = CondValue.getConstantInt()) {
@ -853,9 +853,9 @@ void SCCPSolver::visitSelectInst(SelectInst &I) {
TVal.getConstant() == FVal.getConstant())
return markConstant(&I, FVal.getConstant());
if (TVal.isUndefined()) // select ?, undef, X -> X.
if (TVal.isUnknown()) // select ?, undef, X -> X.
return mergeInValue(&I, FVal);
if (FVal.isUndefined()) // select ?, X, undef -> X.
if (FVal.isUnknown()) // select ?, X, undef -> X.
return mergeInValue(&I, TVal);
markOverdefined(&I);
}
@ -894,7 +894,7 @@ void SCCPSolver::visitBinaryOperator(Instruction &I) {
NonOverdefVal = &V2State;
if (NonOverdefVal) {
if (NonOverdefVal->isUndefined()) {
if (NonOverdefVal->isUnknown()) {
// Could annihilate value.
if (I.getOpcode() == Instruction::And)
markConstant(IV, &I, Constant::getNullValue(I.getType()));
@ -938,7 +938,7 @@ void SCCPSolver::visitCmpInst(CmpInst &I) {
return markConstant(IV, &I, C);
}
// If operands are still undefined, wait for it to resolve.
// If operands are still unknown, wait for it to resolve.
if (!V1State.isOverdefined() && !V2State.isOverdefined())
return;
@ -971,7 +971,7 @@ void SCCPSolver::visitGetElementPtrInst(GetElementPtrInst &I) {
for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i) {
LatticeVal State = getValueState(I.getOperand(i));
if (State.isUndefined())
if (State.isUnknown())
return; // Operands are not resolved yet.
if (State.isOverdefined())
@ -1017,7 +1017,7 @@ void SCCPSolver::visitLoadInst(LoadInst &I) {
return markAnythingOverdefined(&I);
LatticeVal PtrVal = getValueState(I.getOperand(0));
if (PtrVal.isUndefined()) return; // The pointer is not resolved yet!
if (PtrVal.isUnknown()) return; // The pointer is not resolved yet!
LatticeVal &IV = ValueState[&I];
if (IV.isOverdefined()) return;
@ -1078,7 +1078,7 @@ CallOverdefined:
AI != E; ++AI) {
LatticeVal State = getValueState(*AI);
if (State.isUndefined())
if (State.isUnknown())
return; // Operands are not resolved yet.
if (State.isOverdefined())
return markOverdefined(I);
@ -1252,14 +1252,14 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
// 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())
if (LV.isUnknown())
markOverdefined(LV, &I);
}
continue;
}
LatticeVal &LV = getValueState(&I);
if (!LV.isUndefined()) continue;
if (!LV.isUnknown()) continue;
// extractvalue is safe; check here because the argument is a struct.
if (isa<ExtractValueInst>(I))
@ -1298,7 +1298,7 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
case Instruction::FDiv:
case Instruction::FRem:
// Floating-point binary operation: be conservative.
if (Op0LV.isUndefined() && Op1LV.isUndefined())
if (Op0LV.isUnknown() && Op1LV.isUnknown())
markForcedConstant(&I, Constant::getNullValue(ITy));
else
markOverdefined(&I);
@ -1318,7 +1318,7 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
case Instruction::Mul:
case Instruction::And:
// Both operands undef -> undef
if (Op0LV.isUndefined() && Op1LV.isUndefined())
if (Op0LV.isUnknown() && Op1LV.isUnknown())
break;
// undef * X -> 0. X could be zero.
// undef & X -> 0. X could be zero.
@ -1327,7 +1327,7 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
case Instruction::Or:
// Both operands undef -> undef
if (Op0LV.isUndefined() && Op1LV.isUndefined())
if (Op0LV.isUnknown() && Op1LV.isUnknown())
break;
// undef | X -> -1. X could be -1.
markForcedConstant(&I, Constant::getAllOnesValue(ITy));
@ -1337,7 +1337,7 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
// 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()) {
if (Op0LV.isUnknown() && Op1LV.isUnknown()) {
markForcedConstant(&I, Constant::getNullValue(ITy));
return true;
}
@ -1350,7 +1350,7 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
case Instruction::URem:
// X / undef -> undef. No change.
// X % undef -> undef. No change.
if (Op1LV.isUndefined()) break;
if (Op1LV.isUnknown()) break;
// X / 0 -> undef. No change.
// X % 0 -> undef. No change.
@ -1364,7 +1364,7 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
case Instruction::AShr:
// X >>a undef -> undef.
if (Op1LV.isUndefined()) break;
if (Op1LV.isUnknown()) break;
// Shifting by the bitwidth or more is undefined.
if (Op1LV.isConstant()) {
@ -1381,7 +1381,7 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
case Instruction::Shl:
// X << undef -> undef.
// X >> undef -> undef.
if (Op1LV.isUndefined()) break;
if (Op1LV.isUnknown()) break;
// Shifting by the bitwidth or more is undefined.
if (Op1LV.isConstant()) {
@ -1398,13 +1398,13 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
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 (Op0LV.isUnknown()) {
if (!Op1LV.isConstant()) // Pick the constant one if there is any.
Op1LV = getValueState(I.getOperand(2));
} else if (Op1LV.isUndefined()) {
} else if (Op1LV.isUnknown()) {
// c ? undef : undef -> undef. No change.
Op1LV = getValueState(I.getOperand(2));
if (Op1LV.isUndefined())
if (Op1LV.isUnknown())
break;
// Otherwise, c ? undef : x -> x.
} else {
@ -1457,7 +1457,7 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
TerminatorInst *TI = BB.getTerminator();
if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
if (!BI->isConditional()) continue;
if (!getValueState(BI->getCondition()).isUndefined())
if (!getValueState(BI->getCondition()).isUnknown())
continue;
// If the input to SCCP is actually branch on undef, fix the undef to
@ -1479,7 +1479,7 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
if (!SI->getNumCases())
continue;
if (!getValueState(SI->getCondition()).isUndefined())
if (!getValueState(SI->getCondition()).isUnknown())
continue;
// If the input to SCCP is actually switch on undef, fix the undef to