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Diffstat (limited to 'contrib/llvm/lib/Transforms/Scalar/SCCP.cpp')
-rw-r--r--contrib/llvm/lib/Transforms/Scalar/SCCP.cpp250
1 files changed, 173 insertions, 77 deletions
diff --git a/contrib/llvm/lib/Transforms/Scalar/SCCP.cpp b/contrib/llvm/lib/Transforms/Scalar/SCCP.cpp
index 083412ed942d..196a847fc0ea 100644
--- a/contrib/llvm/lib/Transforms/Scalar/SCCP.cpp
+++ b/contrib/llvm/lib/Transforms/Scalar/SCCP.cpp
@@ -156,7 +156,7 @@ namespace {
///
class SCCPSolver : public InstVisitor<SCCPSolver> {
const TargetData *TD;
- SmallPtrSet<BasicBlock*, 8> BBExecutable;// The BBs that are executable.
+ SmallPtrSet<BasicBlock*, 8> BBExecutable; // The BBs that are executable.
DenseMap<Value*, LatticeVal> ValueState; // The state each value is in.
/// StructValueState - This maintains ValueState for values that have
@@ -241,7 +241,7 @@ public:
/// this method must be called.
void AddTrackedFunction(Function *F) {
// Add an entry, F -> undef.
- if (const StructType *STy = dyn_cast<StructType>(F->getReturnType())) {
+ if (StructType *STy = dyn_cast<StructType>(F->getReturnType())) {
MRVFunctionsTracked.insert(F);
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
TrackedMultipleRetVals.insert(std::make_pair(std::make_pair(F, i),
@@ -302,7 +302,7 @@ public:
/// markAnythingOverdefined - Mark the specified value overdefined. This
/// works with both scalars and structs.
void markAnythingOverdefined(Value *V) {
- if (const StructType *STy = dyn_cast<StructType>(V->getType()))
+ if (StructType *STy = dyn_cast<StructType>(V->getType()))
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
markOverdefined(getStructValueState(V, i), V);
else
@@ -417,7 +417,7 @@ private:
else if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C))
LV.markConstant(CS->getOperand(i)); // Constants are constant.
else if (isa<ConstantAggregateZero>(C)) {
- const Type *FieldTy = cast<StructType>(V->getType())->getElementType(i);
+ Type *FieldTy = cast<StructType>(V->getType())->getElementType(i);
LV.markConstant(Constant::getNullValue(FieldTy));
} else
LV.markOverdefined(); // Unknown sort of constant.
@@ -471,9 +471,9 @@ private:
/// UsersOfOverdefinedPHIs map for PN, remove them now.
void RemoveFromOverdefinedPHIs(Instruction *I, PHINode *PN) {
if (UsersOfOverdefinedPHIs.empty()) return;
- std::multimap<PHINode*, Instruction*>::iterator It, E;
- tie(It, E) = UsersOfOverdefinedPHIs.equal_range(PN);
- while (It != E) {
+ 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
@@ -486,9 +486,9 @@ private:
/// (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) {
- std::multimap<PHINode*, Instruction*>::iterator J, E;
- tie(J, E) = UsersOfOverdefinedPHIs.equal_range(PN);
- for (; J != E; ++J)
+ 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));
@@ -515,6 +515,7 @@ private:
void visitShuffleVectorInst(ShuffleVectorInst &I);
void visitExtractValueInst(ExtractValueInst &EVI);
void visitInsertValueInst(InsertValueInst &IVI);
+ void visitLandingPadInst(LandingPadInst &I) { markAnythingOverdefined(&I); }
// Instructions that cannot be folded away.
void visitStoreInst (StoreInst &I);
@@ -528,8 +529,12 @@ private:
visitTerminatorInst(II);
}
void visitCallSite (CallSite CS);
+ void visitResumeInst (TerminatorInst &I) { /*returns void*/ }
void visitUnwindInst (TerminatorInst &I) { /*returns void*/ }
void visitUnreachableInst(TerminatorInst &I) { /*returns void*/ }
+ void visitFenceInst (FenceInst &I) { /*returns void*/ }
+ void visitAtomicCmpXchgInst (AtomicCmpXchgInst &I) { markOverdefined(&I); }
+ void visitAtomicRMWInst (AtomicRMWInst &I) { markOverdefined(&I); }
void visitAllocaInst (Instruction &I) { markOverdefined(&I); }
void visitVAArgInst (Instruction &I) { markAnythingOverdefined(&I); }
@@ -577,6 +582,10 @@ void SCCPSolver::getFeasibleSuccessors(TerminatorInst &TI,
}
if (SwitchInst *SI = dyn_cast<SwitchInst>(&TI)) {
+ if (TI.getNumSuccessors() < 2) {
+ Succs[0] = true;
+ return;
+ }
LatticeVal SCValue = getValueState(SI->getCondition());
ConstantInt *CI = SCValue.getConstantInt();
@@ -637,6 +646,9 @@ bool SCCPSolver::isEdgeFeasible(BasicBlock *From, BasicBlock *To) {
return true;
if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
+ if (SI->getNumSuccessors() < 2)
+ return true;
+
LatticeVal SCValue = getValueState(SI->getCondition());
ConstantInt *CI = SCValue.getConstantInt();
@@ -692,13 +704,14 @@ void SCCPSolver::visitPHINode(PHINode &PN) {
// 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)
+ 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 (; I != E; ++I)
+ for (ItTy I = Range.first, E = Range.second; I != E; ++I)
Users.push_back(I->second);
while (!Users.empty())
visit(Users.pop_back_val());
@@ -772,7 +785,7 @@ void SCCPSolver::visitReturnInst(ReturnInst &I) {
// Handle functions that return multiple values.
if (!TrackedMultipleRetVals.empty()) {
- if (const StructType *STy = dyn_cast<StructType>(ResultOp->getType()))
+ if (StructType *STy = dyn_cast<StructType>(ResultOp->getType()))
if (MRVFunctionsTracked.count(F))
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
mergeInValue(TrackedMultipleRetVals[std::make_pair(F, i)], F,
@@ -825,7 +838,7 @@ void SCCPSolver::visitExtractValueInst(ExtractValueInst &EVI) {
}
void SCCPSolver::visitInsertValueInst(InsertValueInst &IVI) {
- const StructType *STy = dyn_cast<StructType>(IVI.getType());
+ StructType *STy = dyn_cast<StructType>(IVI.getType());
if (STy == 0)
return markOverdefined(&IVI);
@@ -925,7 +938,7 @@ void SCCPSolver::visitBinaryOperator(Instruction &I) {
// 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()))
+ else if (VectorType *PT = dyn_cast<VectorType>(I.getType()))
markConstant(IV, &I, Constant::getAllOnesValue(PT));
else
markConstant(IV, &I,
@@ -1179,8 +1192,8 @@ void SCCPSolver::visitGetElementPtrInst(GetElementPtrInst &I) {
}
Constant *Ptr = Operands[0];
- markConstant(&I, ConstantExpr::getGetElementPtr(Ptr, &Operands[0]+1,
- Operands.size()-1));
+ ArrayRef<Constant *> Indices(Operands.begin() + 1, Operands.end());
+ markConstant(&I, ConstantExpr::getGetElementPtr(Ptr, Indices));
}
void SCCPSolver::visitStoreInst(StoreInst &SI) {
@@ -1278,7 +1291,7 @@ CallOverdefined:
// If we can constant fold this, mark the result of the call as a
// constant.
- if (Constant *C = ConstantFoldCall(F, Operands.data(), Operands.size()))
+ if (Constant *C = ConstantFoldCall(F, Operands))
return markConstant(I, C);
}
@@ -1303,7 +1316,7 @@ CallOverdefined:
continue;
}
- if (const StructType *STy = dyn_cast<StructType>(AI->getType())) {
+ if (StructType *STy = dyn_cast<StructType>(AI->getType())) {
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
LatticeVal CallArg = getStructValueState(*CAI, i);
mergeInValue(getStructValueState(AI, i), AI, CallArg);
@@ -1315,7 +1328,7 @@ CallOverdefined:
}
// If this is a single/zero retval case, see if we're tracking the function.
- if (const StructType *STy = dyn_cast<StructType>(F->getReturnType())) {
+ if (StructType *STy = dyn_cast<StructType>(F->getReturnType())) {
if (!MRVFunctionsTracked.count(F))
goto CallOverdefined; // Not tracking this callee.
@@ -1419,67 +1432,116 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
// Look for instructions which produce undef values.
if (I->getType()->isVoidTy()) continue;
- if (const StructType *STy = dyn_cast<StructType>(I->getType())) {
- // Only a few things that can be structs matter for undef. Just send
- // all their results to overdefined. We could be more precise than this
- // but it isn't worth bothering.
- if (isa<CallInst>(I) || isa<SelectInst>(I)) {
- for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
- LatticeVal &LV = getStructValueState(I, i);
- if (LV.isUndefined())
- markOverdefined(LV, I);
- }
+ if (StructType *STy = dyn_cast<StructType>(I->getType())) {
+ // Only a few things that can be structs matter for undef.
+
+ // Tracked calls must never be marked overdefined in ResolvedUndefsIn.
+ if (CallSite CS = CallSite(I))
+ if (Function *F = CS.getCalledFunction())
+ if (MRVFunctionsTracked.count(F))
+ continue;
+
+ // extractvalue and insertvalue don't need to be marked; they are
+ // tracked as precisely as their operands.
+ if (isa<ExtractValueInst>(I) || isa<InsertValueInst>(I))
+ continue;
+
+ // Send the results of everything else to overdefined. We could be
+ // 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())
+ markOverdefined(LV, I);
}
continue;
}
-
+
LatticeVal &LV = getValueState(I);
if (!LV.isUndefined()) continue;
- // No instructions using structs need disambiguation.
- if (I->getOperand(0)->getType()->isStructTy())
+ // extractvalue is safe; check here because the argument is a struct.
+ if (isa<ExtractValueInst>(I))
continue;
- // Get the lattice values of the first two operands for use below.
+ // Compute the operand LatticeVals, for convenience below.
+ // Anything taking a struct is conservatively assumed to require
+ // overdefined markings.
+ if (I->getOperand(0)->getType()->isStructTy()) {
+ markOverdefined(I);
+ return true;
+ }
LatticeVal Op0LV = getValueState(I->getOperand(0));
LatticeVal Op1LV;
if (I->getNumOperands() == 2) {
- // No instructions using structs need disambiguation.
- if (I->getOperand(1)->getType()->isStructTy())
- continue;
-
- // If this is a two-operand instruction, and if both operands are
- // undefs, the result stays undef.
+ if (I->getOperand(1)->getType()->isStructTy()) {
+ markOverdefined(I);
+ return true;
+ }
+
Op1LV = getValueState(I->getOperand(1));
- if (Op0LV.isUndefined() && Op1LV.isUndefined())
- continue;
}
-
// If this is an instructions whose result is defined even if the input is
// not fully defined, propagate the information.
- const Type *ITy = I->getType();
+ Type *ITy = I->getType();
switch (I->getOpcode()) {
- default: break; // Leave the instruction as an undef.
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Trunc:
+ case Instruction::FPTrunc:
+ case Instruction::BitCast:
+ break; // Any undef -> undef
+ case Instruction::FSub:
+ case Instruction::FAdd:
+ case Instruction::FMul:
+ case Instruction::FDiv:
+ case Instruction::FRem:
+ // Floating-point binary operation: be conservative.
+ if (Op0LV.isUndefined() && Op1LV.isUndefined())
+ markForcedConstant(I, Constant::getNullValue(ITy));
+ else
+ markOverdefined(I);
+ return true;
case Instruction::ZExt:
- // 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.
- case Instruction::SIToFP: // some FP values are not possible, just use 0.
- case Instruction::UIToFP: // some FP values are not possible, just use 0.
+ case Instruction::SExt:
+ case Instruction::FPToUI:
+ case Instruction::FPToSI:
+ case Instruction::FPExt:
+ case Instruction::PtrToInt:
+ case Instruction::IntToPtr:
+ case Instruction::SIToFP:
+ case Instruction::UIToFP:
+ // undef -> 0; some outputs are impossible
markForcedConstant(I, Constant::getNullValue(ITy));
return true;
case Instruction::Mul:
case Instruction::And:
+ // Both operands undef -> undef
+ if (Op0LV.isUndefined() && Op1LV.isUndefined())
+ break;
// undef * X -> 0. X could be zero.
// undef & X -> 0. X could be zero.
markForcedConstant(I, Constant::getNullValue(ITy));
return true;
case Instruction::Or:
+ // Both operands undef -> undef
+ if (Op0LV.isUndefined() && Op1LV.isUndefined())
+ break;
// undef | X -> -1. X could be -1.
markForcedConstant(I, Constant::getAllOnesValue(ITy));
return true;
+ case Instruction::Xor:
+ // 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()) {
+ markForcedConstant(I, Constant::getNullValue(ITy));
+ return true;
+ }
+ // undef ^ X -> undef
+ break;
+
case Instruction::SDiv:
case Instruction::UDiv:
case Instruction::SRem:
@@ -1494,26 +1556,24 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
return true;
case Instruction::AShr:
- // undef >>s X -> undef. No change.
- if (Op0LV.isUndefined()) break;
-
- // X >>s undef -> X. X could be 0, X could have the high-bit known set.
- if (Op0LV.isConstant())
- markForcedConstant(I, Op0LV.getConstant());
- else
- markOverdefined(I);
+ // X >>a undef -> undef.
+ if (Op1LV.isUndefined()) break;
+
+ // undef >>a X -> all ones
+ markForcedConstant(I, Constant::getAllOnesValue(ITy));
return true;
case Instruction::LShr:
case Instruction::Shl:
- // undef >> X -> undef. No change.
- // undef << X -> undef. No change.
- if (Op0LV.isUndefined()) break;
-
- // X >> undef -> 0. X could be 0.
- // X << undef -> 0. X could be 0.
+ // X << undef -> undef.
+ // X >> undef -> undef.
+ if (Op1LV.isUndefined()) break;
+
+ // undef << X -> 0
+ // undef >> X -> 0
markForcedConstant(I, Constant::getNullValue(ITy));
return true;
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 (!Op1LV.isConstant()) // Pick the constant one if there is any.
@@ -1533,9 +1593,35 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
else
markOverdefined(I);
return true;
+ case Instruction::Load:
+ // A load here means one of two things: a load of undef from a global,
+ // a load from an unknown pointer. Either way, having it return undef
+ // is okay.
+ break;
+ case Instruction::ICmp:
+ // X == undef -> undef. Other comparisons get more complicated.
+ if (cast<ICmpInst>(I)->isEquality())
+ break;
+ 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
+ case Instruction::Invoke: {
+ // There are two reasons a call can have an undef result
+ // 1. It could be tracked.
+ // 2. It could be constant-foldable.
+ // Because of the way we solve return values, tracked calls must
+ // never be marked overdefined in ResolvedUndefsIn.
+ if (Function *F = CallSite(I).getCalledFunction())
+ if (TrackedRetVals.count(F))
+ break;
+
+ // If the call is constant-foldable, we mark it overdefined because
+ // we do not know what return values are valid.
+ markOverdefined(I);
+ return true;
+ }
+ default:
+ // If we don't know what should happen here, conservatively mark it
// overdefined.
markOverdefined(I);
return true;
@@ -1621,15 +1707,25 @@ FunctionPass *llvm::createSCCPPass() {
static void DeleteInstructionInBlock(BasicBlock *BB) {
DEBUG(dbgs() << " BasicBlock Dead:" << *BB);
++NumDeadBlocks;
-
- // Delete the instructions backwards, as it has a reduced likelihood of
- // having to update as many def-use and use-def chains.
- while (!isa<TerminatorInst>(BB->begin())) {
- Instruction *I = --BasicBlock::iterator(BB->getTerminator());
-
- if (!I->use_empty())
- I->replaceAllUsesWith(UndefValue::get(I->getType()));
- BB->getInstList().erase(I);
+
+ // Check to see if there are non-terminating instructions to delete.
+ if (isa<TerminatorInst>(BB->begin()))
+ return;
+
+ // Delete the instructions backwards, as it has a reduced likelihood of having
+ // to update as many def-use and use-def chains.
+ Instruction *EndInst = BB->getTerminator(); // Last not to be deleted.
+ while (EndInst != BB->begin()) {
+ // Delete the next to last instruction.
+ BasicBlock::iterator I = EndInst;
+ Instruction *Inst = --I;
+ if (!Inst->use_empty())
+ Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
+ if (isa<LandingPadInst>(Inst)) {
+ EndInst = Inst;
+ continue;
+ }
+ BB->getInstList().erase(Inst);
++NumInstRemoved;
}
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-03 04:56:38 +0000