[llvm-commits] [llvm] r85788 - /llvm/trunk/lib/Transforms/Scalar/SCCP.cpp
Chris Lattner
sabre at nondot.org
Sun Nov 1 21:55:41 PST 2009
Author: lattner
Date: Sun Nov 1 23:55:40 2009
New Revision: 85788
URL: http://llvm.org/viewvc/llvm-project?rev=85788&view=rev
Log:
switch the main 'ValueState' map from being an std::map to being
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.
Modified:
llvm/trunk/lib/Transforms/Scalar/SCCP.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/SCCP.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SCCP.cpp?rev=85788&r1=85787&r2=85788&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SCCP.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SCCP.cpp Sun Nov 1 23:55:40 2009
@@ -155,7 +155,7 @@
///
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 @@
}
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
}
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 @@
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 @@
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 @@
// 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 @@
//
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::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 @@
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::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::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.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 (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 (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 (In1.isOverdefined() || In2.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()) {
+ 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!
- }
-
- 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;
- }
+ 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;
- }
+ // 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;
- markOverdefined(IV, &I);
- } else if (V1State.isConstant() && V2State.isConstant()) {
- markConstant(IV, &I,
- ConstantExpr::get(I.getOpcode(), V1State.getConstant(),
- V2State.getConstant()));
- }
+ // 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.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 (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 (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;
- }
+ // 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;
- markOverdefined(IV, &I);
- } else if (V1State.isConstant() && V2State.isConstant()) {
- markConstant(IV, &I, ConstantExpr::getCompare(I.getPredicate(),
- V1State.getConstant(),
- V2State.getConstant()));
- }
+ // 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 @@
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 @@
}
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 @@
// 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 @@
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 @@
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 @@
// 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 @@
// 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 @@
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 @@
// 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 @@
// 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 @@
// 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 @@
// 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 @@
}
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;
}
}
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