X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FTransforms%2FScalar%2FSCCP.cpp;h=99d757da78e947ed387101d6fe6edf4a2a0c313a;hb=fe6f4e4d31aa5fd0840887883ffff45ae0e9295a;hp=48c8d90c62cd212ccb5b1d0cb7a38862a31a5c32;hpb=054ddf799b5487b85f6bc1d856c4e2a4978da4f7;p=oota-llvm.git diff --git a/lib/Transforms/Scalar/SCCP.cpp b/lib/Transforms/Scalar/SCCP.cpp index 48c8d90c62c..99d757da78e 100644 --- a/lib/Transforms/Scalar/SCCP.cpp +++ b/lib/Transforms/Scalar/SCCP.cpp @@ -17,33 +17,32 @@ // //===----------------------------------------------------------------------===// -#define DEBUG_TYPE "sccp" #include "llvm/Transforms/Scalar.h" -#include "llvm/Transforms/IPO.h" -#include "llvm/Constants.h" -#include "llvm/DerivedTypes.h" -#include "llvm/Instructions.h" -#include "llvm/Pass.h" -#include "llvm/Analysis/ConstantFolding.h" -#include "llvm/Analysis/ValueTracking.h" -#include "llvm/Transforms/Utils/Local.h" -#include "llvm/Target/TargetData.h" -#include "llvm/Support/CallSite.h" -#include "llvm/Support/Debug.h" -#include "llvm/Support/ErrorHandling.h" -#include "llvm/Support/InstVisitor.h" -#include "llvm/Support/raw_ostream.h" #include "llvm/ADT/DenseMap.h" #include "llvm/ADT/DenseSet.h" #include "llvm/ADT/PointerIntPair.h" #include "llvm/ADT/SmallPtrSet.h" #include "llvm/ADT/SmallVector.h" #include "llvm/ADT/Statistic.h" -#include "llvm/ADT/STLExtras.h" +#include "llvm/Analysis/ConstantFolding.h" +#include "llvm/IR/CallSite.h" +#include "llvm/IR/Constants.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/DerivedTypes.h" +#include "llvm/IR/InstVisitor.h" +#include "llvm/IR/Instructions.h" +#include "llvm/Pass.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/ErrorHandling.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Target/TargetLibraryInfo.h" +#include "llvm/Transforms/IPO.h" +#include "llvm/Transforms/Utils/Local.h" #include -#include using namespace llvm; +#define DEBUG_TYPE "sccp" + STATISTIC(NumInstRemoved, "Number of instructions removed"); STATISTIC(NumDeadBlocks , "Number of basic blocks unreachable"); @@ -59,7 +58,7 @@ class LatticeVal { enum LatticeValueTy { /// undefined - This LLVM Value has no known value yet. undefined, - + /// constant - This LLVM Value has a specific constant value. constant, @@ -68,7 +67,7 @@ class LatticeVal { /// with another (different) constant, it goes to overdefined, instead of /// asserting. forcedconstant, - + /// overdefined - This instruction is not known to be constant, and we know /// it has a value. overdefined @@ -77,30 +76,30 @@ class LatticeVal { /// Val: This stores the current lattice value along with the Constant* for /// the constant if this is a 'constant' or 'forcedconstant' value. PointerIntPair Val; - + LatticeValueTy getLatticeValue() const { return Val.getInt(); } - + public: LatticeVal() : Val(0, undefined) {} - + bool isUndefined() const { return getLatticeValue() == undefined; } bool isConstant() const { return getLatticeValue() == constant || getLatticeValue() == forcedconstant; } bool isOverdefined() const { return getLatticeValue() == overdefined; } - + Constant *getConstant() const { assert(isConstant() && "Cannot get the constant of a non-constant!"); return Val.getPointer(); } - + /// markOverdefined - Return true if this is a change in status. bool markOverdefined() { if (isOverdefined()) return false; - + Val.setInt(overdefined); return true; } @@ -111,17 +110,17 @@ public: assert(getConstant() == V && "Marking constant with different value"); return false; } - + if (isUndefined()) { Val.setInt(constant); assert(V && "Marking constant with NULL"); Val.setPointer(V); } else { - assert(getLatticeValue() == forcedconstant && + assert(getLatticeValue() == forcedconstant && "Cannot move from overdefined to constant!"); // Stay at forcedconstant if the constant is the same. if (V == getConstant()) return false; - + // Otherwise, we go to overdefined. Assumptions made based on the // forced value are possibly wrong. Assuming this is another constant // could expose a contradiction. @@ -137,7 +136,7 @@ public: return dyn_cast(getConstant()); return 0; } - + void markForcedConstant(Constant *V) { assert(isUndefined() && "Can't force a defined value!"); Val.setInt(forcedconstant); @@ -155,7 +154,8 @@ namespace { /// Constant Propagation. /// class SCCPSolver : public InstVisitor { - const TargetData *TD; + const DataLayout *DL; + const TargetLibraryInfo *TLI; SmallPtrSet BBExecutable; // The BBs that are executable. DenseMap ValueState; // The state each value is in. @@ -163,7 +163,7 @@ class SCCPSolver : public InstVisitor { /// StructType, for example for formal arguments, calls, insertelement, etc. /// DenseMap, LatticeVal> StructValueState; - + /// 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 /// the global, to the currently known value. If the value becomes @@ -178,7 +178,7 @@ class SCCPSolver : public InstVisitor { /// TrackedMultipleRetVals - Same as TrackedRetVals, but used for functions /// that return multiple values. DenseMap, LatticeVal> TrackedMultipleRetVals; - + /// MRVFunctionsTracked - Each function in TrackedMultipleRetVals is /// represented here for efficient lookup. SmallPtrSet MRVFunctionsTracked; @@ -187,7 +187,7 @@ class SCCPSolver : public InstVisitor { /// arguments we make optimistic assumptions about and try to prove as /// constants. SmallPtrSet TrackingIncomingArguments; - + /// The reason for two worklists is that overdefined is the lowest state /// on the lattice, and moving things to overdefined as fast as possible /// makes SCCP converge much faster. @@ -201,16 +201,13 @@ class SCCPSolver : public InstVisitor { SmallVector 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 UsersOfOverdefinedPHIs; - /// KnownFeasibleEdges - Entries in this set are edges which have already had /// PHI nodes retriggered. typedef std::pair Edge; DenseSet KnownFeasibleEdges; public: - SCCPSolver(const TargetData *td) : TD(td) {} + SCCPSolver(const DataLayout *DL, const TargetLibraryInfo *tli) + : DL(DL), TLI(tli) {} /// MarkBlockExecutable - This method can be used by clients to mark all of /// the blocks that are known to be intrinsically live in the processed unit. @@ -218,7 +215,7 @@ public: /// This returns true if the block was not considered live before. bool MarkBlockExecutable(BasicBlock *BB) { if (!BBExecutable.insert(BB)) return false; - DEBUG(dbgs() << "Marking Block Executable: " << BB->getName() << "\n"); + DEBUG(dbgs() << "Marking Block Executable: " << BB->getName() << '\n'); BBWorkList.push_back(BB); // Add the block to the work list! return true; } @@ -253,7 +250,7 @@ public: void AddArgumentTrackedFunction(Function *F) { TrackingIncomingArguments.insert(F); } - + /// Solve - Solve for constants and executable blocks. /// void Solve(); @@ -274,13 +271,6 @@ public: assert(I != ValueState.end() && "V is not in valuemap!"); return I->second; } - - /*LatticeVal getStructLatticeValueFor(Value *V, unsigned i) const { - DenseMap, LatticeVal>::const_iterator I = - StructValueState.find(std::make_pair(V, i)); - assert(I != StructValueState.end() && "V is not in valuemap!"); - return I->second; - }*/ /// getTrackedRetVals - Get the inferred return value map. /// @@ -308,7 +298,7 @@ public: else markOverdefined(V); } - + private: // markConstant - Make a value be marked as "constant". If the value // is not already a constant, add it to the instruction work list so that @@ -322,7 +312,7 @@ private: else InstWorkList.push_back(V); } - + void markConstant(Value *V, Constant *C) { assert(!V->getType()->isStructTy() && "Should use other method"); markConstant(ValueState[V], V, C); @@ -338,14 +328,14 @@ private: else 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. void markOverdefined(LatticeVal &IV, Value *V) { if (!IV.markOverdefined()) return; - + DEBUG(dbgs() << "markOverdefined: "; if (Function *F = dyn_cast(V)) dbgs() << "Function '" << F->getName() << "'\n"; @@ -365,7 +355,7 @@ private: else if (IV.getConstant() != MergeWithV.getConstant()) markOverdefined(IV, V); } - + void mergeInValue(Value *V, LatticeVal MergeWithV) { assert(!V->getType()->isStructTy() && "Should use other method"); mergeInValue(ValueState[V], V, MergeWithV); @@ -390,7 +380,7 @@ private: if (!isa(V)) LV.markConstant(C); // Constants are constant } - + // All others are underdefined by default. return LV; } @@ -412,21 +402,20 @@ private: return LV; // Common case, already in the map. if (Constant *C = dyn_cast(V)) { - if (isa(C)) - ; // Undef values remain undefined. - else if (ConstantStruct *CS = dyn_cast(C)) - LV.markConstant(CS->getOperand(i)); // Constants are constant. - else if (isa(C)) { - Type *FieldTy = cast(V->getType())->getElementType(i); - LV.markConstant(Constant::getNullValue(FieldTy)); - } else + Constant *Elt = C->getAggregateElement(i); + + if (Elt == 0) LV.markOverdefined(); // Unknown sort of constant. + else if (isa(Elt)) + ; // Undef values remain undefined. + else + LV.markConstant(Elt); // Constants are constant. } - + // All others are underdefined by default. return LV; } - + /// markEdgeExecutable - Mark a basic block as executable, adding it to the BB /// work list if it is not already executable. @@ -439,7 +428,7 @@ private: // feasible that wasn't before. Revisit the PHI nodes in the block // because they have potentially new operands. DEBUG(dbgs() << "Marking Edge Executable: " << Source->getName() - << " -> " << Dest->getName() << "\n"); + << " -> " << Dest->getName() << '\n'); PHINode *PN; for (BasicBlock::iterator I = Dest->begin(); @@ -451,7 +440,7 @@ private: // getFeasibleSuccessors - Return a vector of booleans to indicate which // successors are reachable from a given terminator instruction. // - void getFeasibleSuccessors(TerminatorInst &TI, SmallVector &Succs); + void getFeasibleSuccessors(TerminatorInst &TI, SmallVectorImpl &Succs); // isEdgeFeasible - Return true if the control flow edge from the 'From' basic // block to the 'To' basic block is currently feasible. @@ -466,33 +455,6 @@ 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::iterator ItTy; - std::pair 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::iterator ItTy; - std::pair 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; @@ -530,7 +492,6 @@ private: } 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); } @@ -540,7 +501,7 @@ private: void visitInstruction(Instruction &I) { // If a new instruction is added to LLVM that we don't handle. - dbgs() << "SCCP: Don't know how to handle: " << I; + dbgs() << "SCCP: Don't know how to handle: " << I << '\n'; markAnythingOverdefined(&I); // Just in case } }; @@ -552,14 +513,14 @@ private: // successors are reachable from a given terminator instruction. // void SCCPSolver::getFeasibleSuccessors(TerminatorInst &TI, - SmallVector &Succs) { + SmallVectorImpl &Succs) { Succs.resize(TI.getNumSuccessors()); if (BranchInst *BI = dyn_cast(&TI)) { if (BI->isUnconditional()) { Succs[0] = true; return; } - + LatticeVal BCValue = getValueState(BI->getCondition()); ConstantInt *CI = BCValue.getConstantInt(); if (CI == 0) { @@ -569,44 +530,44 @@ void SCCPSolver::getFeasibleSuccessors(TerminatorInst &TI, Succs[0] = Succs[1] = true; return; } - + // Constant condition variables mean the branch can only go a single way. Succs[CI->isZero()] = true; return; } - + if (isa(TI)) { // Invoke instructions successors are always executable. Succs[0] = Succs[1] = true; return; } - + if (SwitchInst *SI = dyn_cast(&TI)) { - if (TI.getNumSuccessors() < 2) { + if (!SI->getNumCases()) { Succs[0] = true; return; } LatticeVal SCValue = getValueState(SI->getCondition()); ConstantInt *CI = SCValue.getConstantInt(); - + if (CI == 0) { // Overdefined or undefined condition? // All destinations are executable! if (!SCValue.isUndefined()) Succs.assign(TI.getNumSuccessors(), true); return; } - - Succs[SI->findCaseValue(CI)] = true; + + Succs[SI->findCaseValue(CI).getSuccessorIndex()] = true; return; } - + // TODO: This could be improved if the operand is a [cast of a] BlockAddress. if (isa(&TI)) { // Just mark all destinations executable! Succs.assign(TI.getNumSuccessors(), true); return; } - + #ifndef NDEBUG dbgs() << "Unknown terminator instruction: " << TI << '\n'; #endif @@ -628,7 +589,7 @@ bool SCCPSolver::isEdgeFeasible(BasicBlock *From, BasicBlock *To) { if (BranchInst *BI = dyn_cast(TI)) { if (BI->isUnconditional()) return true; - + LatticeVal BCValue = getValueState(BI->getCondition()); // Overdefined condition variables mean the branch could go either way, @@ -636,40 +597,33 @@ bool SCCPSolver::isEdgeFeasible(BasicBlock *From, BasicBlock *To) { ConstantInt *CI = BCValue.getConstantInt(); if (CI == 0) return !BCValue.isUndefined(); - + // Constant condition variables mean the branch can only go a single way. return BI->getSuccessor(CI->isZero()) == To; } - + // Invoke instructions successors are always executable. if (isa(TI)) return true; - + if (SwitchInst *SI = dyn_cast(TI)) { - if (SI->getNumSuccessors() < 2) + if (SI->getNumCases() < 1) return true; LatticeVal SCValue = getValueState(SI->getCondition()); ConstantInt *CI = SCValue.getConstantInt(); - + if (CI == 0) return !SCValue.isUndefined(); - // Make sure to skip the "default value" which isn't a value - for (unsigned i = 1, E = SI->getNumSuccessors(); i != E; ++i) - if (SI->getSuccessorValue(i) == CI) // Found the taken branch. - return SI->getSuccessor(i) == To; - - // If the constant value is not equal to any of the branches, we must - // execute default branch. - return SI->getDefaultDest() == To; + return SI->findCaseValue(CI).getCaseSuccessor() == To; } - + // Just mark all destinations executable! // TODO: This could be improved if the operand is a [cast of a] BlockAddress. if (isa(TI)) return true; - + #ifndef NDEBUG dbgs() << "Unknown terminator instruction: " << *TI << '\n'; #endif @@ -699,30 +653,15 @@ void SCCPSolver::visitPHINode(PHINode &PN) { // TODO: We could do a lot better than this if code actually uses this. 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::iterator ItTy; - std::pair Range = UsersOfOverdefinedPHIs.equal_range(&PN); - - if (Range.first == Range.second) - return; - - SmallVector 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. if (PN.getNumIncomingValues() > 64) 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 // constant, and they agree with each other, the PHI becomes the identical @@ -736,7 +675,7 @@ void SCCPSolver::visitPHINode(PHINode &PN) { if (!isEdgeFeasible(PN.getIncomingBlock(i), PN.getParent())) continue; - + if (IV.isOverdefined()) // PHI node becomes overdefined! return markOverdefined(&PN); @@ -744,11 +683,11 @@ void SCCPSolver::visitPHINode(PHINode &PN) { OperandVal = IV.getConstant(); continue; } - + // There is already a reachable operand. If we conflict with it, // then the PHI node becomes overdefined. If we agree with it, we // can continue on. - + // Check to see if there are two different constants merging, if so, the PHI // node is overdefined. if (IV.getConstant() != OperandVal) @@ -764,15 +703,12 @@ void SCCPSolver::visitPHINode(PHINode &PN) { markConstant(&PN, OperandVal); // Acquire operand value } - - - void SCCPSolver::visitReturnInst(ReturnInst &I) { if (I.getNumOperands() == 0) return; // ret void Function *F = I.getParent()->getParent(); Value *ResultOp = I.getOperand(0); - + // If we are tracking the return value of this function, merge it in. if (!TrackedRetVals.empty() && !ResultOp->getType()->isStructTy()) { DenseMap::iterator TFRVI = @@ -782,7 +718,7 @@ void SCCPSolver::visitReturnInst(ReturnInst &I) { return; } } - + // Handle functions that return multiple values. if (!TrackedMultipleRetVals.empty()) { if (StructType *STy = dyn_cast(ResultOp->getType())) @@ -790,7 +726,7 @@ void SCCPSolver::visitReturnInst(ReturnInst &I) { for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) mergeInValue(TrackedMultipleRetVals[std::make_pair(F, i)], F, getStructValueState(ResultOp, i)); - + } } @@ -811,7 +747,7 @@ void SCCPSolver::visitCastInst(CastInst &I) { if (OpSt.isOverdefined()) // Inherit overdefinedness of operand markOverdefined(&I); else if (OpSt.isConstant()) // Propagate constant value - markConstant(&I, ConstantExpr::getCast(I.getOpcode(), + markConstant(&I, ConstantExpr::getCast(I.getOpcode(), OpSt.getConstant(), I.getType())); } @@ -821,7 +757,7 @@ void SCCPSolver::visitExtractValueInst(ExtractValueInst &EVI) { // structs in structs. if (EVI.getType()->isStructTy()) return markAnythingOverdefined(&EVI); - + // If this is extracting from more than one level of struct, we don't know. if (EVI.getNumIndices() != 1) return markOverdefined(&EVI); @@ -841,15 +777,15 @@ void SCCPSolver::visitInsertValueInst(InsertValueInst &IVI) { StructType *STy = dyn_cast(IVI.getType()); if (STy == 0) return markOverdefined(&IVI); - + // If this has more than one index, we can't handle it, drive all results to // undef. if (IVI.getNumIndices() != 1) return markAnythingOverdefined(&IVI); - + Value *Aggr = IVI.getAggregateOperand(); unsigned Idx = *IVI.idx_begin(); - + // Compute the result based on what we're inserting. for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) { // This passes through all values that aren't the inserted element. @@ -858,7 +794,7 @@ void SCCPSolver::visitInsertValueInst(InsertValueInst &IVI) { mergeInValue(getStructValueState(&IVI, i), &IVI, EltVal); continue; } - + Value *Val = IVI.getInsertedValueOperand(); if (Val->getType()->isStructTy()) // We don't track structs in structs. @@ -875,25 +811,25 @@ void SCCPSolver::visitSelectInst(SelectInst &I) { // TODO: We could do a lot better than this if code actually uses this. if (I.getType()->isStructTy()) return markAnythingOverdefined(&I); - + LatticeVal CondValue = getValueState(I.getCondition()); if (CondValue.isUndefined()) return; - + if (ConstantInt *CondCB = CondValue.getConstantInt()) { 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()); - + // select ?, C, C -> C. - if (TVal.isConstant() && FVal.isConstant() && + if (TVal.isConstant() && FVal.isConstant() && TVal.getConstant() == FVal.getConstant()) return markConstant(&I, FVal.getConstant()); @@ -908,7 +844,7 @@ void SCCPSolver::visitSelectInst(SelectInst &I) { 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; @@ -916,14 +852,14 @@ void SCCPSolver::visitBinaryOperator(Instruction &I) { 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) { @@ -945,7 +881,7 @@ void SCCPSolver::visitBinaryOperator(Instruction &I) { Constant::getAllOnesValue(I.getType())); return; } - + if (I.getOpcode() == Instruction::And) { // X and 0 = 0 if (NonOverdefVal->getConstant()->isNullValue()) @@ -959,64 +895,6 @@ 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(I.getOperand(0))) - if (PHINode *PN2 = dyn_cast(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); } @@ -1029,75 +907,13 @@ void SCCPSolver::visitCmpInst(CmpInst &I) { if (IV.isOverdefined()) return; if (V1State.isConstant() && V2State.isConstant()) - return markConstant(IV, &I, ConstantExpr::getCompare(I.getPredicate(), - V1State.getConstant(), + 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(I.getOperand(0))) - if (PHINode *PN2 = dyn_cast(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); } @@ -1135,7 +951,7 @@ void SCCPSolver::visitInsertElementInst(InsertElementInst &I) { EltState.getConstant(), IdxState.getConstant())); else if (ValState.isUndefined() && EltState.isConstant() && - IdxState.isConstant()) + IdxState.isConstant()) markConstant(&I,ConstantExpr::getInsertElement(UndefValue::get(I.getType()), EltState.getConstant(), IdxState.getConstant())); @@ -1153,17 +969,17 @@ void SCCPSolver::visitShuffleVectorInst(ShuffleVectorInst &I) { if (MaskState.isUndefined() || (V1State.isUndefined() && V2State.isUndefined())) return; // Undefined output if mask or both inputs undefined. - + if (V1State.isOverdefined() || V2State.isOverdefined() || MaskState.isOverdefined()) { markOverdefined(&I); } else { // A mix of constant/undef inputs. - Constant *V1 = V1State.isConstant() ? + Constant *V1 = V1State.isConstant() ? V1State.getConstant() : UndefValue::get(I.getType()); - Constant *V2 = V2State.isConstant() ? + Constant *V2 = V2State.isConstant() ? V2State.getConstant() : UndefValue::get(I.getType()); - Constant *Mask = MaskState.isConstant() ? + Constant *Mask = MaskState.isConstant() ? MaskState.getConstant() : UndefValue::get(I.getOperand(2)->getType()); markConstant(&I, ConstantExpr::getShuffleVector(V1, V2, Mask)); } @@ -1183,7 +999,7 @@ void SCCPSolver::visitGetElementPtrInst(GetElementPtrInst &I) { LatticeVal State = getValueState(I.getOperand(i)); if (State.isUndefined()) return; // Operands are not resolved yet. - + if (State.isOverdefined()) return markOverdefined(&I); @@ -1200,10 +1016,10 @@ void SCCPSolver::visitStoreInst(StoreInst &SI) { // If this store is of a struct, ignore it. if (SI.getOperand(0)->getType()->isStructTy()) return; - + if (TrackedGlobals.empty() || !isa(SI.getOperand(1))) return; - + GlobalVariable *GV = cast(SI.getOperand(1)); DenseMap::iterator I = TrackedGlobals.find(GV); if (I == TrackedGlobals.end() || I->second.isOverdefined()) return; @@ -1221,22 +1037,22 @@ void SCCPSolver::visitLoadInst(LoadInst &I) { // If this load is of a struct, just mark the result overdefined. if (I.getType()->isStructTy()) return markAnythingOverdefined(&I); - + LatticeVal PtrVal = getValueState(I.getOperand(0)); if (PtrVal.isUndefined()) return; // The pointer is not resolved yet! - + LatticeVal &IV = ValueState[&I]; if (IV.isOverdefined()) return; if (!PtrVal.isConstant() || I.isVolatile()) return markOverdefined(IV, &I); - + Constant *Ptr = PtrVal.getConstant(); // load null -> null if (isa(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(Ptr)) { if (!TrackedGlobals.empty()) { @@ -1251,7 +1067,7 @@ void SCCPSolver::visitLoadInst(LoadInst &I) { } // Transform load from a constant into a constant if possible. - if (Constant *C = ConstantFoldLoadFromConstPtr(Ptr, TD)) + if (Constant *C = ConstantFoldLoadFromConstPtr(Ptr, DL)) return markConstant(IV, &I, C); // Otherwise we cannot say for certain what value this load will produce. @@ -1262,7 +1078,7 @@ void SCCPSolver::visitLoadInst(LoadInst &I) { void SCCPSolver::visitCallSite(CallSite CS) { Function *F = CS.getCalledFunction(); Instruction *I = CS.getInstruction(); - + // The common case is that we aren't tracking the callee, either because we // are not doing interprocedural analysis or the callee is indirect, or is // external. Handle these cases first. @@ -1270,17 +1086,17 @@ void SCCPSolver::visitCallSite(CallSite CS) { CallOverdefined: // Void return and not tracking callee, just bail. if (I->getType()->isVoidTy()) return; - + // Otherwise, if we have a single return value case, and if the function is // a declaration, maybe we can constant fold it. if (F && F->isDeclaration() && !I->getType()->isStructTy() && canConstantFoldCallTo(F)) { - + SmallVector Operands; for (CallSite::arg_iterator AI = CS.arg_begin(), E = CS.arg_end(); AI != E; ++AI) { LatticeVal State = getValueState(*AI); - + if (State.isUndefined()) return; // Operands are not resolved yet. if (State.isOverdefined()) @@ -1288,10 +1104,10 @@ CallOverdefined: assert(State.isConstant() && "Unknown state!"); Operands.push_back(State.getConstant()); } - + // If we can constant fold this, mark the result of the call as a // constant. - if (Constant *C = ConstantFoldCall(F, Operands)) + if (Constant *C = ConstantFoldCall(F, Operands, TLI)) return markConstant(I, C); } @@ -1304,7 +1120,7 @@ CallOverdefined: // the formal arguments of the function. if (!TrackingIncomingArguments.empty() && TrackingIncomingArguments.count(F)){ MarkBlockExecutable(F->begin()); - + // Propagate information from this call site into the callee. CallSite::arg_iterator CAI = CS.arg_begin(); for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); @@ -1315,7 +1131,7 @@ CallOverdefined: markOverdefined(AI); continue; } - + if (StructType *STy = dyn_cast(AI->getType())) { for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) { LatticeVal CallArg = getStructValueState(*CAI, i); @@ -1326,22 +1142,22 @@ CallOverdefined: } } } - + // If this is a single/zero retval case, see if we're tracking the function. if (StructType *STy = dyn_cast(F->getReturnType())) { if (!MRVFunctionsTracked.count(F)) goto CallOverdefined; // Not tracking this callee. - + // If we are tracking this callee, propagate the result of the function // into this call site. for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) - mergeInValue(getStructValueState(I, i), I, + mergeInValue(getStructValueState(I, i), I, TrackedMultipleRetVals[std::make_pair(F, i)]); } else { DenseMap::iterator TFRVI = TrackedRetVals.find(F); if (TFRVI == TrackedRetVals.end()) goto CallOverdefined; // Not tracking this callee. - + // If so, propagate the return value of the callee into this call result. mergeInValue(I, TFRVI->second); } @@ -1359,18 +1175,17 @@ void SCCPSolver::Solve() { DEBUG(dbgs() << "\nPopped off OI-WL: " << *I << '\n'); // "I" got into the work list because it either made the transition from - // bottom to constant + // bottom to constant, or to overdefined. // // Anything on this worklist that is overdefined need not be visited // since all of its users will have already been marked as overdefined // Update all of the users of this instruction's value. // - for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); - UI != E; ++UI) - if (Instruction *I = dyn_cast(*UI)) - OperandChangedState(I); + for (User *U : I->users()) + if (Instruction *UI = dyn_cast(U)) + OperandChangedState(UI); } - + // Process the instruction work list. while (!InstWorkList.empty()) { Value *I = InstWorkList.pop_back_val(); @@ -1385,10 +1200,9 @@ void SCCPSolver::Solve() { // Update all of the users of this instruction's value. // if (I->getType()->isStructTy() || !getValueState(I).isOverdefined()) - for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); - UI != E; ++UI) - if (Instruction *I = dyn_cast(*UI)) - OperandChangedState(I); + for (User *U : I->users()) + if (Instruction *UI = dyn_cast(U)) + OperandChangedState(UI); } // Process the basic block work list. @@ -1427,21 +1241,31 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) { for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { if (!BBExecutable.count(BB)) continue; - + for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { // Look for instructions which produce undef values. if (I->getType()->isVoidTy()) continue; - + if (StructType *STy = dyn_cast(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(I) || isa(I)) { - for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) { - LatticeVal &LV = getStructValueState(I, i); - if (LV.isUndefined()) - markOverdefined(LV, I); - } + // 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(I) || isa(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; } @@ -1449,16 +1273,31 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) { LatticeVal &LV = getValueState(I); if (!LV.isUndefined()) continue; + // extractvalue is safe; check here because the argument is a struct. + if (isa(I)) + continue; + + // 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) + if (I->getNumOperands() == 2) { + if (I->getOperand(1)->getType()->isStructTy()) { + markOverdefined(I); + return true; + } + Op1LV = getValueState(I->getOperand(1)); + } // If this is an instructions whose result is defined even if the input is // not fully defined, propagate the information. Type *ITy = I->getType(); switch (I->getOpcode()) { - case Instruction::ExtractValue: - break; // Extract of undef -> undef case Instruction::Add: case Instruction::Sub: case Instruction::Trunc: @@ -1524,12 +1363,12 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) { // X / undef -> undef. No change. // X % undef -> undef. No change. if (Op1LV.isUndefined()) break; - + // undef / X -> 0. X could be maxint. // undef % X -> 0. X could be 1. markForcedConstant(I, Constant::getNullValue(ITy)); return true; - + case Instruction::AShr: // X >>a undef -> undef. if (Op1LV.isUndefined()) break; @@ -1562,7 +1401,7 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) { } else { // Leave Op1LV as Operand(1)'s LatticeValue. } - + if (Op1LV.isConstant()) markForcedConstant(I, Op1LV.getConstant()); else @@ -1579,6 +1418,22 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) { break; markOverdefined(I); return true; + case Instruction::Call: + 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. @@ -1586,7 +1441,7 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) { return true; } } - + // Check to see if we have a branch or switch on an undefined value. If so // we force the branch to go one way or the other to make the successor // values live. It doesn't really matter which way we force it. @@ -1595,7 +1450,7 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) { if (!BI->isConditional()) continue; if (!getValueState(BI->getCondition()).isUndefined()) continue; - + // If the input to SCCP is actually branch on undef, fix the undef to // false. if (isa(BI->getCondition())) { @@ -1603,7 +1458,7 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) { markEdgeExecutable(BB, TI->getSuccessor(1)); return true; } - + // Otherwise, it is a branch on a symbolic value which is currently // considered to be undef. Handle this by forcing the input value to the // branch to false. @@ -1611,22 +1466,22 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) { ConstantInt::getFalse(TI->getContext())); return true; } - + if (SwitchInst *SI = dyn_cast(TI)) { - if (SI->getNumSuccessors() < 2) // no cases + if (!SI->getNumCases()) continue; if (!getValueState(SI->getCondition()).isUndefined()) continue; - + // If the input to SCCP is actually switch on undef, fix the undef to // the first constant. if (isa(SI->getCondition())) { - SI->setCondition(SI->getCaseValue(1)); - markEdgeExecutable(BB, TI->getSuccessor(1)); + SI->setCondition(SI->case_begin().getCaseValue()); + markEdgeExecutable(BB, SI->case_begin().getCaseSuccessor()); return true; } - - markForcedConstant(SI->getCondition(), SI->getCaseValue(1)); + + markForcedConstant(SI->getCondition(), SI->case_begin().getCaseValue()); return true; } } @@ -1642,6 +1497,9 @@ namespace { /// Sparse Conditional Constant Propagator. /// struct SCCP : public FunctionPass { + void getAnalysisUsage(AnalysisUsage &AU) const override { + AU.addRequired(); + } static char ID; // Pass identification, replacement for typeid SCCP() : FunctionPass(ID) { initializeSCCPPass(*PassRegistry::getPassRegistry()); @@ -1650,7 +1508,7 @@ namespace { // runOnFunction - Run the Sparse Conditional Constant Propagation // algorithm, and return true if the function was modified. // - bool runOnFunction(Function &F); + bool runOnFunction(Function &F) override; }; } // end anonymous namespace @@ -1666,15 +1524,25 @@ 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(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(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(Inst)) { + EndInst = Inst; + continue; + } + BB->getInstList().erase(Inst); ++NumInstRemoved; } } @@ -1683,8 +1551,14 @@ static void DeleteInstructionInBlock(BasicBlock *BB) { // and return true if the function was modified. // bool SCCP::runOnFunction(Function &F) { + if (skipOptnoneFunction(F)) + return false; + DEBUG(dbgs() << "SCCP on function '" << F.getName() << "'\n"); - SCCPSolver Solver(getAnalysisIfAvailable()); + const DataLayoutPass *DLP = getAnalysisIfAvailable(); + const DataLayout *DL = DLP ? &DLP->getDataLayout() : 0; + const TargetLibraryInfo *TLI = &getAnalysis(); + SCCPSolver Solver(DL, TLI); // Mark the first block of the function as being executable. Solver.MarkBlockExecutable(F.begin()); @@ -1713,7 +1587,7 @@ bool SCCP::runOnFunction(Function &F) { MadeChanges = true; continue; } - + // Iterate over all of the instructions in a function, replacing them with // constants if we have found them to be of constant values. // @@ -1721,25 +1595,25 @@ bool SCCP::runOnFunction(Function &F) { Instruction *Inst = BI++; if (Inst->getType()->isVoidTy() || isa(Inst)) continue; - + // TODO: Reconstruct structs from their elements. if (Inst->getType()->isStructTy()) continue; - + LatticeVal IV = Solver.getLatticeValueFor(Inst); if (IV.isOverdefined()) continue; - + Constant *Const = IV.isConstant() ? IV.getConstant() : UndefValue::get(Inst->getType()); - DEBUG(dbgs() << " Constant: " << *Const << " = " << *Inst); + DEBUG(dbgs() << " Constant: " << *Const << " = " << *Inst << '\n'); // Replaces all of the uses of a variable with uses of the constant. Inst->replaceAllUsesWith(Const); - + // Delete the instruction. Inst->eraseFromParent(); - + // Hey, we just changed something! MadeChanges = true; ++NumInstRemoved; @@ -1756,16 +1630,23 @@ namespace { /// Constant Propagation. /// struct IPSCCP : public ModulePass { + void getAnalysisUsage(AnalysisUsage &AU) const override { + AU.addRequired(); + } static char ID; IPSCCP() : ModulePass(ID) { initializeIPSCCPPass(*PassRegistry::getPassRegistry()); } - bool runOnModule(Module &M); + bool runOnModule(Module &M) override; }; } // end anonymous namespace char IPSCCP::ID = 0; -INITIALIZE_PASS(IPSCCP, "ipsccp", +INITIALIZE_PASS_BEGIN(IPSCCP, "ipsccp", + "Interprocedural Sparse Conditional Constant Propagation", + false, false) +INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo) +INITIALIZE_PASS_END(IPSCCP, "ipsccp", "Interprocedural Sparse Conditional Constant Propagation", false, false) @@ -1779,21 +1660,20 @@ static bool AddressIsTaken(const GlobalValue *GV) { // Delete any dead constantexpr klingons. GV->removeDeadConstantUsers(); - for (Value::const_use_iterator UI = GV->use_begin(), E = GV->use_end(); - UI != E; ++UI) { - const User *U = *UI; - if (const StoreInst *SI = dyn_cast(U)) { + for (const Use &U : GV->uses()) { + const User *UR = U.getUser(); + if (const StoreInst *SI = dyn_cast(UR)) { if (SI->getOperand(0) == GV || SI->isVolatile()) return true; // Storing addr of GV. - } else if (isa(U) || isa(U)) { + } else if (isa(UR) || isa(UR)) { // Make sure we are calling the function, not passing the address. - ImmutableCallSite CS(cast(U)); - if (!CS.isCallee(UI)) + ImmutableCallSite CS(cast(UR)); + if (!CS.isCallee(&U)) return true; - } else if (const LoadInst *LI = dyn_cast(U)) { + } else if (const LoadInst *LI = dyn_cast(UR)) { if (LI->isVolatile()) return true; - } else if (isa(U)) { + } else if (isa(UR)) { // blockaddress doesn't take the address of the function, it takes addr // of label. } else { @@ -1804,7 +1684,10 @@ static bool AddressIsTaken(const GlobalValue *GV) { } bool IPSCCP::runOnModule(Module &M) { - SCCPSolver Solver(getAnalysisIfAvailable()); + DataLayoutPass *DLP = getAnalysisIfAvailable(); + const DataLayout *DL = DLP ? &DLP->getDataLayout() : 0; + const TargetLibraryInfo *TLI = &getAnalysis(); + SCCPSolver Solver(DL, TLI); // AddressTakenFunctions - This set keeps track of the address-taken functions // that are in the input. As IPSCCP runs through and simplifies code, @@ -1812,19 +1695,19 @@ bool IPSCCP::runOnModule(Module &M) { // address-taken-ness. Because of this, we keep track of their addresses from // the first pass so we can use them for the later simplification pass. SmallPtrSet AddressTakenFunctions; - + // Loop over all functions, marking arguments to those with their addresses // taken or that are external as overdefined. // for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) { if (F->isDeclaration()) continue; - + // If this is a strong or ODR definition of this function, then we can // propagate information about its result into callsites of it. if (!F->mayBeOverridden()) Solver.AddTrackedFunction(F); - + // If this function only has direct calls that we can see, we can track its // arguments and return value aggressively, and can assume it is not called // unless we see evidence to the contrary. @@ -1839,7 +1722,7 @@ bool IPSCCP::runOnModule(Module &M) { // Assume the function is called. Solver.MarkBlockExecutable(F->begin()); - + // Assume nothing about the incoming arguments. for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); AI != E; ++AI) @@ -1877,17 +1760,17 @@ bool IPSCCP::runOnModule(Module &M) { for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); AI != E; ++AI) { if (AI->use_empty() || AI->getType()->isStructTy()) continue; - + // TODO: Could use getStructLatticeValueFor to find out if the entire // result is a constant and replace it entirely if so. LatticeVal IV = Solver.getLatticeValueFor(AI); if (IV.isOverdefined()) continue; - + Constant *CST = IV.isConstant() ? IV.getConstant() : UndefValue::get(AI->getType()); DEBUG(dbgs() << "*** Arg " << *AI << " = " << *CST <<"\n"); - + // Replaces all of the uses of a variable with uses of the // constant. AI->replaceAllUsesWith(CST); @@ -1916,27 +1799,27 @@ bool IPSCCP::runOnModule(Module &M) { new UnreachableInst(M.getContext(), BB); continue; } - + for (BasicBlock::iterator BI = BB->begin(), E = BB->end(); BI != E; ) { Instruction *Inst = BI++; if (Inst->getType()->isVoidTy() || Inst->getType()->isStructTy()) continue; - + // TODO: Could use getStructLatticeValueFor to find out if the entire // result is a constant and replace it entirely if so. - + LatticeVal IV = Solver.getLatticeValueFor(Inst); if (IV.isOverdefined()) continue; - + Constant *Const = IV.isConstant() ? IV.getConstant() : UndefValue::get(Inst->getType()); - DEBUG(dbgs() << " Constant: " << *Const << " = " << *Inst); + DEBUG(dbgs() << " Constant: " << *Const << " = " << *Inst << '\n'); // Replaces all of the uses of a variable with uses of the // constant. Inst->replaceAllUsesWith(Const); - + // Delete the instruction. if (!isa(Inst) && !isa(Inst)) Inst->eraseFromParent(); @@ -1953,8 +1836,9 @@ bool IPSCCP::runOnModule(Module &M) { for (unsigned i = 0, e = BlocksToErase.size(); i != e; ++i) { // If there are any PHI nodes in this successor, drop entries for BB now. BasicBlock *DeadBB = BlocksToErase[i]; - for (Value::use_iterator UI = DeadBB->use_begin(), UE = DeadBB->use_end(); - UI != UE; ) { + for (Value::user_iterator UI = DeadBB->user_begin(), + UE = DeadBB->user_end(); + UI != UE;) { // Grab the user and then increment the iterator early, as the user // will be deleted. Step past all adjacent uses from the same user. Instruction *I = dyn_cast(*UI); @@ -1978,15 +1862,15 @@ bool IPSCCP::runOnModule(Module &M) { llvm_unreachable("Didn't fold away reference to block!"); } #endif - + // Make this an uncond branch to the first successor. TerminatorInst *TI = I->getParent()->getTerminator(); BranchInst::Create(TI->getSuccessor(0), TI); - + // Remove entries in successor phi nodes to remove edges. for (unsigned i = 1, e = TI->getNumSuccessors(); i != e; ++i) TI->getSuccessor(i)->removePredecessor(TI->getParent()); - + // Remove the old terminator. TI->eraseFromParent(); } @@ -2009,7 +1893,7 @@ bool IPSCCP::runOnModule(Module &M) { // last use of a function, the order of processing functions would affect // whether other functions are optimizable. SmallVector ReturnsToZap; - + // TODO: Process multiple value ret instructions also. const DenseMap &RV = Solver.getTrackedRetVals(); for (DenseMap::const_iterator I = RV.begin(), @@ -2017,11 +1901,11 @@ bool IPSCCP::runOnModule(Module &M) { Function *F = I->first; if (I->second.isOverdefined() || F->getReturnType()->isVoidTy()) continue; - + // We can only do this if we know that nothing else can call the function. if (!F->hasLocalLinkage() || AddressTakenFunctions.count(F)) continue; - + for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) if (ReturnInst *RI = dyn_cast(BB->getTerminator())) if (!isa(RI->getOperand(0))) @@ -2033,9 +1917,9 @@ bool IPSCCP::runOnModule(Module &M) { Function *F = ReturnsToZap[i]->getParent()->getParent(); ReturnsToZap[i]->setOperand(0, UndefValue::get(F->getReturnType())); } - - // If we inferred constant or undef values for globals variables, we can delete - // the global and any stores that remain to it. + + // If we inferred constant or undef values for globals variables, we can + // delete the global and any stores that remain to it. const DenseMap &TG = Solver.getTrackedGlobals(); for (DenseMap::const_iterator I = TG.begin(), E = TG.end(); I != E; ++I) { @@ -2044,7 +1928,7 @@ bool IPSCCP::runOnModule(Module &M) { "Overdefined values should have been taken out of the map!"); DEBUG(dbgs() << "Found that GV '" << GV->getName() << "' is constant!\n"); while (!GV->use_empty()) { - StoreInst *SI = cast(GV->use_back()); + StoreInst *SI = cast(GV->user_back()); SI->eraseFromParent(); } M.getGlobalList().erase(GV);