From fef8bb24de86ff41d09a7787c6c52b058a853e39 Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Sat, 25 Jul 2009 01:13:03 +0000 Subject: [PATCH] Instead of eagerly creating new SCEVs to replace all SCEVs that are affected after a PHI node has been analyzed, just remove affected SCEVs from the Scalars map, so that they'll be (lazily) recreated as needed. This avoids creating SCEV objects that aren't actually needed. Also, rewrite the associated def-use walking code to be non-recursive and to continue traversing past Instructions that don't have an entry in the Scalars map. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77032 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Analysis/ScalarEvolution.h | 29 +--- .../Analysis/ScalarEvolutionExpressions.h | 74 +++----- lib/Analysis/ScalarEvolution.cpp | 159 ++++++------------ 3 files changed, 84 insertions(+), 178 deletions(-) diff --git a/include/llvm/Analysis/ScalarEvolution.h b/include/llvm/Analysis/ScalarEvolution.h index cfa504d6706..872c5ec0e49 100644 --- a/include/llvm/Analysis/ScalarEvolution.h +++ b/include/llvm/Analysis/ScalarEvolution.h @@ -96,15 +96,9 @@ namespace llvm { /// bool isAllOnesValue() const; - /// replaceSymbolicValuesWithConcrete - If this SCEV internally references - /// the symbolic value "Sym", construct and return a new SCEV that produces - /// the same value, but which uses the concrete value Conc instead of the - /// symbolic value. If this SCEV does not use the symbolic value, it - /// returns itself. - virtual const SCEV * - replaceSymbolicValuesWithConcrete(const SCEV *Sym, - const SCEV *Conc, - ScalarEvolution &SE) const = 0; + /// hasOperand - Test whether this SCEV has Op as a direct or + /// indirect operand. + virtual bool hasOperand(const SCEV *Op) const = 0; /// dominates - Return true if elements that makes up this SCEV dominates /// the specified basic block. @@ -145,10 +139,7 @@ namespace llvm { virtual const Type *getType() const; virtual bool hasComputableLoopEvolution(const Loop *L) const; virtual void print(raw_ostream &OS) const; - virtual const SCEV * - replaceSymbolicValuesWithConcrete(const SCEV *Sym, - const SCEV *Conc, - ScalarEvolution &SE) const; + virtual bool hasOperand(const SCEV *Op) const; virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const { return true; @@ -252,13 +243,11 @@ namespace llvm { /// SCEVs. const SCEV *createNodeForGEP(Operator *GEP); - /// ReplaceSymbolicValueWithConcrete - This looks up the computed SCEV value - /// for the specified instruction and replaces any references to the - /// symbolic value SymName with the specified value. This is used during - /// PHI resolution. - void ReplaceSymbolicValueWithConcrete(Instruction *I, - const SCEV *SymName, - const SCEV *NewVal); + /// ForgetSymbolicValue - This looks up computed SCEV values for all + /// instructions that depend on the given instruction and removes them from + /// the Scalars map if they reference SymName. This is used during PHI + /// resolution. + void ForgetSymbolicName(Instruction *I, const SCEV *SymName); /// getBECount - Subtract the end and start values and divide by the step, /// rounding up, to get the number of times the backedge is executed. Return diff --git a/include/llvm/Analysis/ScalarEvolutionExpressions.h b/include/llvm/Analysis/ScalarEvolutionExpressions.h index 830143b90e0..99df1dfefca 100644 --- a/include/llvm/Analysis/ScalarEvolutionExpressions.h +++ b/include/llvm/Analysis/ScalarEvolutionExpressions.h @@ -52,10 +52,8 @@ namespace llvm { virtual const Type *getType() const; - const SCEV *replaceSymbolicValuesWithConcrete(const SCEV *Sym, - const SCEV *Conc, - ScalarEvolution &SE) const { - return this; + virtual bool hasOperand(const SCEV *) const { + return false; } bool dominates(BasicBlock *BB, DominatorTree *DT) const { @@ -94,6 +92,10 @@ namespace llvm { return Op->hasComputableLoopEvolution(L); } + virtual bool hasOperand(const SCEV *O) const { + return Op == O || Op->hasOperand(O); + } + virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const; /// Methods for support type inquiry through isa, cast, and dyn_cast: @@ -116,15 +118,6 @@ namespace llvm { const SCEV *op, const Type *ty); public: - const SCEV *replaceSymbolicValuesWithConcrete(const SCEV *Sym, - const SCEV *Conc, - ScalarEvolution &SE) const { - const SCEV *H = Op->replaceSymbolicValuesWithConcrete(Sym, Conc, SE); - if (H == Op) - return this; - return SE.getTruncateExpr(H, Ty); - } - virtual void print(raw_ostream &OS) const; /// Methods for support type inquiry through isa, cast, and dyn_cast: @@ -145,15 +138,6 @@ namespace llvm { const SCEV *op, const Type *ty); public: - const SCEV *replaceSymbolicValuesWithConcrete(const SCEV *Sym, - const SCEV *Conc, - ScalarEvolution &SE) const { - const SCEV *H = Op->replaceSymbolicValuesWithConcrete(Sym, Conc, SE); - if (H == Op) - return this; - return SE.getZeroExtendExpr(H, Ty); - } - virtual void print(raw_ostream &OS) const; /// Methods for support type inquiry through isa, cast, and dyn_cast: @@ -174,15 +158,6 @@ namespace llvm { const SCEV *op, const Type *ty); public: - const SCEV *replaceSymbolicValuesWithConcrete(const SCEV *Sym, - const SCEV *Conc, - ScalarEvolution &SE) const { - const SCEV *H = Op->replaceSymbolicValuesWithConcrete(Sym, Conc, SE); - if (H == Op) - return this; - return SE.getSignExtendExpr(H, Ty); - } - virtual void print(raw_ostream &OS) const; /// Methods for support type inquiry through isa, cast, and dyn_cast: @@ -240,6 +215,13 @@ namespace llvm { return HasVarying; } + virtual bool hasOperand(const SCEV *O) const { + for (unsigned i = 0, e = getNumOperands(); i != e; ++i) + if (O == getOperand(i) || getOperand(i)->hasOperand(O)) + return true; + return false; + } + bool dominates(BasicBlock *BB, DominatorTree *DT) const; virtual const Type *getType() const { return getOperand(0)->getType(); } @@ -267,10 +249,6 @@ namespace llvm { : SCEVNAryExpr(ID, T, ops) {} public: - const SCEV *replaceSymbolicValuesWithConcrete(const SCEV *Sym, - const SCEV *Conc, - ScalarEvolution &SE) const; - virtual const char *getOperationStr() const = 0; virtual void print(raw_ostream &OS) const; @@ -353,15 +331,8 @@ namespace llvm { RHS->hasComputableLoopEvolution(L); } - const SCEV *replaceSymbolicValuesWithConcrete(const SCEV *Sym, - const SCEV *Conc, - ScalarEvolution &SE) const { - const SCEV *L = LHS->replaceSymbolicValuesWithConcrete(Sym, Conc, SE); - const SCEV *R = RHS->replaceSymbolicValuesWithConcrete(Sym, Conc, SE); - if (L == LHS && R == RHS) - return this; - else - return SE.getUDivExpr(L, R); + virtual bool hasOperand(const SCEV *O) const { + return O == LHS || O == RHS || LHS->hasOperand(O) || RHS->hasOperand(O); } bool dominates(BasicBlock *BB, DominatorTree *DT) const; @@ -449,14 +420,10 @@ namespace llvm { const SCEV *getNumIterationsInRange(ConstantRange Range, ScalarEvolution &SE) const; - const SCEV *replaceSymbolicValuesWithConcrete(const SCEV *Sym, - const SCEV *Conc, - ScalarEvolution &SE) const; - /// getPostIncExpr - Return an expression representing the value of /// this expression one iteration of the loop ahead. - const SCEV *getPostIncExpr(ScalarEvolution &SE) const { - return SE.getAddExpr(this, getStepRecurrence(SE)); + const SCEVAddRecExpr *getPostIncExpr(ScalarEvolution &SE) const { + return cast(SE.getAddExpr(this, getStepRecurrence(SE))); } bool hasNoUnsignedOverflow() const { return SubclassData & (1 << 0); } @@ -542,11 +509,8 @@ namespace llvm { return false; // not computable } - const SCEV *replaceSymbolicValuesWithConcrete(const SCEV *Sym, - const SCEV *Conc, - ScalarEvolution &SE) const { - if (&*Sym == this) return Conc; - return this; + virtual bool hasOperand(const SCEV *) const { + return false; } bool dominates(BasicBlock *BB, DominatorTree *DT) const; diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index 6b64648f17f..c77c7c40ef1 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -163,12 +163,9 @@ bool SCEVCouldNotCompute::hasComputableLoopEvolution(const Loop *L) const { return false; } -const SCEV * -SCEVCouldNotCompute::replaceSymbolicValuesWithConcrete( - const SCEV *Sym, - const SCEV *Conc, - ScalarEvolution &SE) const { - return this; +bool SCEVCouldNotCompute::hasOperand(const SCEV *) const { + llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!"); + return false; } void SCEVCouldNotCompute::print(raw_ostream &OS) const { @@ -260,39 +257,6 @@ void SCEVCommutativeExpr::print(raw_ostream &OS) const { OS << ")"; } -const SCEV * -SCEVCommutativeExpr::replaceSymbolicValuesWithConcrete( - const SCEV *Sym, - const SCEV *Conc, - ScalarEvolution &SE) const { - for (unsigned i = 0, e = getNumOperands(); i != e; ++i) { - const SCEV *H = - getOperand(i)->replaceSymbolicValuesWithConcrete(Sym, Conc, SE); - if (H != getOperand(i)) { - SmallVector NewOps; - NewOps.reserve(getNumOperands()); - for (unsigned j = 0; j != i; ++j) - NewOps.push_back(getOperand(j)); - NewOps.push_back(H); - for (++i; i != e; ++i) - NewOps.push_back(getOperand(i)-> - replaceSymbolicValuesWithConcrete(Sym, Conc, SE)); - - if (isa(this)) - return SE.getAddExpr(NewOps); - else if (isa(this)) - return SE.getMulExpr(NewOps); - else if (isa(this)) - return SE.getSMaxExpr(NewOps); - else if (isa(this)) - return SE.getUMaxExpr(NewOps); - else - llvm_unreachable("Unknown commutative expr!"); - } - } - return this; -} - bool SCEVNAryExpr::dominates(BasicBlock *BB, DominatorTree *DT) const { for (unsigned i = 0, e = getNumOperands(); i != e; ++i) { if (!getOperand(i)->dominates(BB, DT)) @@ -318,30 +282,6 @@ const Type *SCEVUDivExpr::getType() const { return RHS->getType(); } -const SCEV * -SCEVAddRecExpr::replaceSymbolicValuesWithConcrete(const SCEV *Sym, - const SCEV *Conc, - ScalarEvolution &SE) const { - for (unsigned i = 0, e = getNumOperands(); i != e; ++i) { - const SCEV *H = - getOperand(i)->replaceSymbolicValuesWithConcrete(Sym, Conc, SE); - if (H != getOperand(i)) { - SmallVector NewOps; - NewOps.reserve(getNumOperands()); - for (unsigned j = 0; j != i; ++j) - NewOps.push_back(getOperand(j)); - NewOps.push_back(H); - for (++i; i != e; ++i) - NewOps.push_back(getOperand(i)-> - replaceSymbolicValuesWithConcrete(Sym, Conc, SE)); - - return SE.getAddRecExpr(NewOps, L); - } - } - return this; -} - - bool SCEVAddRecExpr::isLoopInvariant(const Loop *QueryLoop) const { // Add recurrences are never invariant in the function-body (null loop). if (!QueryLoop) @@ -2301,28 +2241,53 @@ const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(const SCEV *LHS, return getUMinExpr(PromotedLHS, PromotedRHS); } -/// ReplaceSymbolicValueWithConcrete - This looks up the computed SCEV value for -/// the specified instruction and replaces any references to the symbolic value -/// SymName with the specified value. This is used during PHI resolution. +/// PushDefUseChildren - Push users of the given Instruction +/// onto the given Worklist. +static void +PushDefUseChildren(Instruction *I, + SmallVectorImpl &Worklist) { + // Push the def-use children onto the Worklist stack. + for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); + UI != UE; ++UI) + Worklist.push_back(cast(UI)); +} + +/// ForgetSymbolicValue - This looks up computed SCEV values for all +/// instructions that depend on the given instruction and removes them from +/// the Scalars map if they reference SymName. This is used during PHI +/// resolution. void -ScalarEvolution::ReplaceSymbolicValueWithConcrete(Instruction *I, - const SCEV *SymName, - const SCEV *NewVal) { - std::map::iterator SI = - Scalars.find(SCEVCallbackVH(I, this)); - if (SI == Scalars.end()) return; +ScalarEvolution::ForgetSymbolicName(Instruction *I, const SCEV *SymName) { + SmallVector Worklist; + PushDefUseChildren(I, Worklist); - const SCEV *NV = - SI->second->replaceSymbolicValuesWithConcrete(SymName, NewVal, *this); - if (NV == SI->second) return; // No change. + SmallPtrSet Visited; + Visited.insert(I); + while (!Worklist.empty()) { + Instruction *I = Worklist.pop_back_val(); + if (!Visited.insert(I)) continue; - SI->second = NV; // Update the scalars map! + std::map::iterator It = + Scalars.find(static_cast(I)); + if (It != Scalars.end()) { + // Short-circuit the def-use traversal if the symbolic name + // ceases to appear in expressions. + if (!It->second->hasOperand(SymName)) + continue; + + // SCEVUnknown for a PHI either means that it has an unrecognized + // structure, or it's a PHI that's in the progress of being computed + // by createNodeForPHI. In the former case, additional loop trip + // count information isn't going to change anything. In the later + // case, createNodeForPHI will perform the necessary updates on its + // own when it gets to that point. + if (!isa(I) || !isa(It->second)) + Scalars.erase(It); + ValuesAtScopes.erase(I); + } - // Any instruction values that use this instruction might also need to be - // updated! - for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); - UI != E; ++UI) - ReplaceSymbolicValueWithConcrete(cast(*UI), SymName, NewVal); + PushDefUseChildren(I, Worklist); + } } /// createNodeForPHI - PHI nodes have two cases. Either the PHI node exists in @@ -2345,7 +2310,8 @@ const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) { // Using this symbolic name for the PHI, analyze the value coming around // the back-edge. - const SCEV *BEValue = getSCEV(PN->getIncomingValue(BackEdge)); + Value *BEValueV = PN->getIncomingValue(BackEdge); + const SCEV *BEValue = getSCEV(BEValueV); // NOTE: If BEValue is loop invariant, we know that the PHI node just // has a special value for the first iteration of the loop. @@ -2382,11 +2348,10 @@ const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) { getAddRecExpr(StartVal, Accum, L); // Okay, for the entire analysis of this edge we assumed the PHI - // to be symbolic. We now need to go back and update all of the - // entries for the scalars that use the PHI (except for the PHI - // itself) to use the new analyzed value instead of the "symbolic" - // value. - ReplaceSymbolicValueWithConcrete(PN, SymbolicName, PHISCEV); + // to be symbolic. We now need to go back and purge all of the + // entries for the scalars that use the symbolic expression. + ForgetSymbolicName(PN, SymbolicName); + Scalars[SCEVCallbackVH(PN, this)] = PHISCEV; return PHISCEV; } } @@ -2408,11 +2373,10 @@ const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) { getAddRecExpr(StartVal, AddRec->getOperand(1), L); // Okay, for the entire analysis of this edge we assumed the PHI - // to be symbolic. We now need to go back and update all of the - // entries for the scalars that use the PHI (except for the PHI - // itself) to use the new analyzed value instead of the "symbolic" - // value. - ReplaceSymbolicValueWithConcrete(PN, SymbolicName, PHISCEV); + // to be symbolic. We now need to go back and purge all of the + // entries for the scalars that use the symbolic expression. + ForgetSymbolicName(PN, SymbolicName); + Scalars[SCEVCallbackVH(PN, this)] = PHISCEV; return PHISCEV; } } @@ -3058,17 +3022,6 @@ PushLoopPHIs(const Loop *L, SmallVectorImpl &Worklist) { Worklist.push_back(PN); } -/// PushDefUseChildren - Push users of the given Instruction -/// onto the given Worklist. -static void -PushDefUseChildren(Instruction *I, - SmallVectorImpl &Worklist) { - // Push the def-use children onto the Worklist stack. - for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); - UI != UE; ++UI) - Worklist.push_back(cast(UI)); -} - const ScalarEvolution::BackedgeTakenInfo & ScalarEvolution::getBackedgeTakenInfo(const Loop *L) { // Initially insert a CouldNotCompute for this loop. If the insertion -- 2.34.1