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-rw-r--r--lib/Transforms/Scalar/SCCP.cpp168
1 files changed, 1 insertions, 167 deletions
diff --git a/lib/Transforms/Scalar/SCCP.cpp b/lib/Transforms/Scalar/SCCP.cpp
index 196a847..f6762ad 100644
--- a/lib/Transforms/Scalar/SCCP.cpp
+++ b/lib/Transforms/Scalar/SCCP.cpp
@@ -201,10 +201,6 @@ class SCCPSolver : public InstVisitor<SCCPSolver> {
SmallVector<BasicBlock*, 64> BBWorkList; // The BasicBlock work list
- /// UsersOfOverdefinedPHIs - Keep track of any users of PHI nodes that are not
- /// overdefined, despite the fact that the PHI node is overdefined.
- std::multimap<PHINode*, Instruction*> UsersOfOverdefinedPHIs;
-
/// KnownFeasibleEdges - Entries in this set are edges which have already had
/// PHI nodes retriggered.
typedef std::pair<BasicBlock*, BasicBlock*> Edge;
@@ -466,33 +462,6 @@ private:
if (BBExecutable.count(I->getParent())) // Inst is executable?
visit(*I);
}
-
- /// RemoveFromOverdefinedPHIs - If I has any entries in the
- /// UsersOfOverdefinedPHIs map for PN, remove them now.
- void RemoveFromOverdefinedPHIs(Instruction *I, PHINode *PN) {
- if (UsersOfOverdefinedPHIs.empty()) return;
- typedef std::multimap<PHINode*, Instruction*>::iterator ItTy;
- std::pair<ItTy, ItTy> Range = UsersOfOverdefinedPHIs.equal_range(PN);
- for (ItTy It = Range.first, E = Range.second; It != E;) {
- if (It->second == I)
- UsersOfOverdefinedPHIs.erase(It++);
- else
- ++It;
- }
- }
-
- /// InsertInOverdefinedPHIs - Insert an entry in the UsersOfOverdefinedPHIS
- /// map for I and PN, but if one is there already, do not create another.
- /// (Duplicate entries do not break anything directly, but can lead to
- /// exponential growth of the table in rare cases.)
- void InsertInOverdefinedPHIs(Instruction *I, PHINode *PN) {
- typedef std::multimap<PHINode*, Instruction*>::iterator ItTy;
- std::pair<ItTy, ItTy> Range = UsersOfOverdefinedPHIs.equal_range(PN);
- for (ItTy J = Range.first, E = Range.second; J != E; ++J)
- if (J->second == I)
- return;
- UsersOfOverdefinedPHIs.insert(std::make_pair(PN, I));
- }
private:
friend class InstVisitor<SCCPSolver>;
@@ -700,23 +669,8 @@ void SCCPSolver::visitPHINode(PHINode &PN) {
if (PN.getType()->isStructTy())
return markAnythingOverdefined(&PN);
- if (getValueState(&PN).isOverdefined()) {
- // There may be instructions using this PHI node that are not overdefined
- // themselves. If so, make sure that they know that the PHI node operand
- // changed.
- typedef std::multimap<PHINode*, Instruction*>::iterator ItTy;
- std::pair<ItTy, ItTy> Range = UsersOfOverdefinedPHIs.equal_range(&PN);
-
- if (Range.first == Range.second)
- return;
-
- SmallVector<Instruction*, 16> Users;
- for (ItTy I = Range.first, E = Range.second; I != E; ++I)
- Users.push_back(I->second);
- while (!Users.empty())
- visit(Users.pop_back_val());
+ if (getValueState(&PN).isOverdefined())
return; // Quick exit
- }
// Super-extra-high-degree PHI nodes are unlikely to ever be marked constant,
// and slow us down a lot. Just mark them overdefined.
@@ -959,64 +913,6 @@ void SCCPSolver::visitBinaryOperator(Instruction &I) {
}
- // If both operands are PHI nodes, it is possible that this instruction has
- // a constant value, despite the fact that the PHI node doesn't. Check for
- // this condition now.
- if (PHINode *PN1 = dyn_cast<PHINode>(I.getOperand(0)))
- if (PHINode *PN2 = dyn_cast<PHINode>(I.getOperand(1)))
- if (PN1->getParent() == PN2->getParent()) {
- // Since the two PHI nodes are in the same basic block, they must have
- // entries for the same predecessors. Walk the predecessor list, and
- // if all of the incoming values are constants, and the result of
- // evaluating this expression with all incoming value pairs is the
- // same, then this expression is a constant even though the PHI node
- // is not a constant!
- LatticeVal Result;
- for (unsigned i = 0, e = PN1->getNumIncomingValues(); i != e; ++i) {
- LatticeVal In1 = getValueState(PN1->getIncomingValue(i));
- BasicBlock *InBlock = PN1->getIncomingBlock(i);
- LatticeVal In2 =getValueState(PN2->getIncomingValueForBlock(InBlock));
-
- if (In1.isOverdefined() || In2.isOverdefined()) {
- Result.markOverdefined();
- break; // Cannot fold this operation over the PHI nodes!
- }
-
- if (In1.isConstant() && In2.isConstant()) {
- Constant *V = ConstantExpr::get(I.getOpcode(), In1.getConstant(),
- In2.getConstant());
- if (Result.isUndefined())
- Result.markConstant(V);
- else if (Result.isConstant() && Result.getConstant() != V) {
- Result.markOverdefined();
- break;
- }
- }
- }
-
- // If we found a constant value here, then we know the instruction is
- // constant despite the fact that the PHI nodes are overdefined.
- if (Result.isConstant()) {
- markConstant(IV, &I, Result.getConstant());
- // Remember that this instruction is virtually using the PHI node
- // operands.
- InsertInOverdefinedPHIs(&I, PN1);
- InsertInOverdefinedPHIs(&I, PN2);
- return;
- }
-
- if (Result.isUndefined())
- return;
-
- // Okay, this really is overdefined now. Since we might have
- // speculatively thought that this was not overdefined before, and
- // added ourselves to the UsersOfOverdefinedPHIs list for the PHIs,
- // make sure to clean out any entries that we put there, for
- // efficiency.
- RemoveFromOverdefinedPHIs(&I, PN1);
- RemoveFromOverdefinedPHIs(&I, PN2);
- }
-
markOverdefined(&I);
}
@@ -1037,68 +933,6 @@ void SCCPSolver::visitCmpInst(CmpInst &I) {
if (!V1State.isOverdefined() && !V2State.isOverdefined())
return;
- // If something is overdefined, use some tricks to avoid ending up and over
- // defined if we can.
-
- // If both operands are PHI nodes, it is possible that this instruction has
- // a constant value, despite the fact that the PHI node doesn't. Check for
- // this condition now.
- if (PHINode *PN1 = dyn_cast<PHINode>(I.getOperand(0)))
- if (PHINode *PN2 = dyn_cast<PHINode>(I.getOperand(1)))
- if (PN1->getParent() == PN2->getParent()) {
- // Since the two PHI nodes are in the same basic block, they must have
- // entries for the same predecessors. Walk the predecessor list, and
- // if all of the incoming values are constants, and the result of
- // evaluating this expression with all incoming value pairs is the
- // same, then this expression is a constant even though the PHI node
- // is not a constant!
- LatticeVal Result;
- for (unsigned i = 0, e = PN1->getNumIncomingValues(); i != e; ++i) {
- LatticeVal In1 = getValueState(PN1->getIncomingValue(i));
- BasicBlock *InBlock = PN1->getIncomingBlock(i);
- LatticeVal In2 =getValueState(PN2->getIncomingValueForBlock(InBlock));
-
- if (In1.isOverdefined() || In2.isOverdefined()) {
- Result.markOverdefined();
- break; // Cannot fold this operation over the PHI nodes!
- }
-
- if (In1.isConstant() && In2.isConstant()) {
- Constant *V = ConstantExpr::getCompare(I.getPredicate(),
- In1.getConstant(),
- In2.getConstant());
- if (Result.isUndefined())
- Result.markConstant(V);
- else if (Result.isConstant() && Result.getConstant() != V) {
- Result.markOverdefined();
- break;
- }
- }
- }
-
- // If we found a constant value here, then we know the instruction is
- // constant despite the fact that the PHI nodes are overdefined.
- if (Result.isConstant()) {
- markConstant(&I, Result.getConstant());
- // Remember that this instruction is virtually using the PHI node
- // operands.
- InsertInOverdefinedPHIs(&I, PN1);
- InsertInOverdefinedPHIs(&I, PN2);
- return;
- }
-
- if (Result.isUndefined())
- return;
-
- // Okay, this really is overdefined now. Since we might have
- // speculatively thought that this was not overdefined before, and
- // added ourselves to the UsersOfOverdefinedPHIs list for the PHIs,
- // make sure to clean out any entries that we put there, for
- // efficiency.
- RemoveFromOverdefinedPHIs(&I, PN1);
- RemoveFromOverdefinedPHIs(&I, PN2);
- }
-
markOverdefined(&I);
}
generated by cgit v1.1 at 2024-12-23 12:04:07 +0000