| //===- PredicateInfo.h - Build PredicateInfo ----------------------*-C++-*-===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| /// |
| /// \file |
| /// This file implements the PredicateInfo analysis, which creates an Extended |
| /// SSA form for operations used in branch comparisons and llvm.assume |
| /// comparisons. |
| /// |
| /// Copies of these operations are inserted into the true/false edge (and after |
| /// assumes), and information attached to the copies. All uses of the original |
| /// operation in blocks dominated by the true/false edge (and assume), are |
| /// replaced with uses of the copies. This enables passes to easily and sparsely |
| /// propagate condition based info into the operations that may be affected. |
| /// |
| /// Example: |
| /// %cmp = icmp eq i32 %x, 50 |
| /// br i1 %cmp, label %true, label %false |
| /// true: |
| /// ret i32 %x |
| /// false: |
| /// ret i32 1 |
| /// |
| /// will become |
| /// |
| /// %cmp = icmp eq i32, %x, 50 |
| /// br i1 %cmp, label %true, label %false |
| /// true: |
| /// %x.0 = call \@llvm.ssa_copy.i32(i32 %x) |
| /// ret i32 %x.0 |
| /// false: |
| /// ret i32 1 |
| /// |
| /// Using getPredicateInfoFor on x.0 will give you the comparison it is |
| /// dominated by (the icmp), and that you are located in the true edge of that |
| /// comparison, which tells you x.0 is 50. |
| /// |
| /// In order to reduce the number of copies inserted, predicateinfo is only |
| /// inserted where it would actually be live. This means if there are no uses of |
| /// an operation dominated by the branch edges, or by an assume, the associated |
| /// predicate info is never inserted. |
| /// |
| /// |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_TRANSFORMS_UTILS_PREDICATEINFO_H |
| #define LLVM_TRANSFORMS_UTILS_PREDICATEINFO_H |
| |
| #include "llvm/ADT/DenseMap.h" |
| #include "llvm/ADT/SmallSet.h" |
| #include "llvm/ADT/ilist.h" |
| #include "llvm/ADT/ilist_node.h" |
| #include "llvm/IR/Instructions.h" |
| #include "llvm/IR/PassManager.h" |
| #include "llvm/IR/Value.h" |
| #include "llvm/IR/ValueHandle.h" |
| #include "llvm/Pass.h" |
| |
| namespace llvm { |
| |
| class AssumptionCache; |
| class DominatorTree; |
| class Function; |
| class IntrinsicInst; |
| class raw_ostream; |
| |
| enum PredicateType { PT_Branch, PT_Assume, PT_Switch }; |
| |
| /// Constraint for a predicate of the form "cmp Pred Op, OtherOp", where Op |
| /// is the value the constraint applies to (the ssa.copy result). |
| struct PredicateConstraint { |
| CmpInst::Predicate Predicate; |
| Value *OtherOp; |
| }; |
| |
| // Base class for all predicate information we provide. |
| // All of our predicate information has at least a comparison. |
| class PredicateBase : public ilist_node<PredicateBase> { |
| public: |
| PredicateType Type; |
| // The original operand before we renamed it. |
| // This can be use by passes, when destroying predicateinfo, to know |
| // whether they can just drop the intrinsic, or have to merge metadata. |
| Value *OriginalOp; |
| // The renamed operand in the condition used for this predicate. For nested |
| // predicates, this is different to OriginalOp which refers to the initial |
| // operand. |
| Value *RenamedOp; |
| // The condition associated with this predicate. |
| Value *Condition; |
| |
| PredicateBase(const PredicateBase &) = delete; |
| PredicateBase &operator=(const PredicateBase &) = delete; |
| PredicateBase() = delete; |
| virtual ~PredicateBase() = default; |
| static bool classof(const PredicateBase *PB) { |
| return PB->Type == PT_Assume || PB->Type == PT_Branch || |
| PB->Type == PT_Switch; |
| } |
| |
| /// Fetch condition in the form of PredicateConstraint, if possible. |
| Optional<PredicateConstraint> getConstraint() const; |
| |
| protected: |
| PredicateBase(PredicateType PT, Value *Op, Value *Condition) |
| : Type(PT), OriginalOp(Op), Condition(Condition) {} |
| }; |
| |
| // Provides predicate information for assumes. Since assumes are always true, |
| // we simply provide the assume instruction, so you can tell your relative |
| // position to it. |
| class PredicateAssume : public PredicateBase { |
| public: |
| IntrinsicInst *AssumeInst; |
| PredicateAssume(Value *Op, IntrinsicInst *AssumeInst, Value *Condition) |
| : PredicateBase(PT_Assume, Op, Condition), AssumeInst(AssumeInst) {} |
| PredicateAssume() = delete; |
| static bool classof(const PredicateBase *PB) { |
| return PB->Type == PT_Assume; |
| } |
| }; |
| |
| // Mixin class for edge predicates. The FROM block is the block where the |
| // predicate originates, and the TO block is the block where the predicate is |
| // valid. |
| class PredicateWithEdge : public PredicateBase { |
| public: |
| BasicBlock *From; |
| BasicBlock *To; |
| PredicateWithEdge() = delete; |
| static bool classof(const PredicateBase *PB) { |
| return PB->Type == PT_Branch || PB->Type == PT_Switch; |
| } |
| |
| protected: |
| PredicateWithEdge(PredicateType PType, Value *Op, BasicBlock *From, |
| BasicBlock *To, Value *Cond) |
| : PredicateBase(PType, Op, Cond), From(From), To(To) {} |
| }; |
| |
| // Provides predicate information for branches. |
| class PredicateBranch : public PredicateWithEdge { |
| public: |
| // If true, SplitBB is the true successor, otherwise it's the false successor. |
| bool TrueEdge; |
| PredicateBranch(Value *Op, BasicBlock *BranchBB, BasicBlock *SplitBB, |
| Value *Condition, bool TakenEdge) |
| : PredicateWithEdge(PT_Branch, Op, BranchBB, SplitBB, Condition), |
| TrueEdge(TakenEdge) {} |
| PredicateBranch() = delete; |
| static bool classof(const PredicateBase *PB) { |
| return PB->Type == PT_Branch; |
| } |
| }; |
| |
| class PredicateSwitch : public PredicateWithEdge { |
| public: |
| Value *CaseValue; |
| // This is the switch instruction. |
| SwitchInst *Switch; |
| PredicateSwitch(Value *Op, BasicBlock *SwitchBB, BasicBlock *TargetBB, |
| Value *CaseValue, SwitchInst *SI) |
| : PredicateWithEdge(PT_Switch, Op, SwitchBB, TargetBB, |
| SI->getCondition()), |
| CaseValue(CaseValue), Switch(SI) {} |
| PredicateSwitch() = delete; |
| static bool classof(const PredicateBase *PB) { |
| return PB->Type == PT_Switch; |
| } |
| }; |
| |
| /// Encapsulates PredicateInfo, including all data associated with memory |
| /// accesses. |
| class PredicateInfo { |
| public: |
| PredicateInfo(Function &, DominatorTree &, AssumptionCache &); |
| ~PredicateInfo(); |
| |
| void verifyPredicateInfo() const; |
| |
| void dump() const; |
| void print(raw_ostream &) const; |
| |
| const PredicateBase *getPredicateInfoFor(const Value *V) const { |
| return PredicateMap.lookup(V); |
| } |
| |
| protected: |
| // Used by PredicateInfo annotater, dumpers, and wrapper pass. |
| friend class PredicateInfoAnnotatedWriter; |
| friend class PredicateInfoPrinterLegacyPass; |
| friend class PredicateInfoBuilder; |
| |
| private: |
| Function &F; |
| |
| // This owns the all the predicate infos in the function, placed or not. |
| iplist<PredicateBase> AllInfos; |
| |
| // This maps from copy operands to Predicate Info. Note that it does not own |
| // the Predicate Info, they belong to the ValueInfo structs in the ValueInfos |
| // vector. |
| DenseMap<const Value *, const PredicateBase *> PredicateMap; |
| // The set of ssa_copy declarations we created with our custom mangling. |
| SmallSet<AssertingVH<Function>, 20> CreatedDeclarations; |
| }; |
| |
| // This pass does eager building and then printing of PredicateInfo. It is used |
| // by |
| // the tests to be able to build, dump, and verify PredicateInfo. |
| class PredicateInfoPrinterLegacyPass : public FunctionPass { |
| public: |
| PredicateInfoPrinterLegacyPass(); |
| |
| static char ID; |
| bool runOnFunction(Function &) override; |
| void getAnalysisUsage(AnalysisUsage &AU) const override; |
| }; |
| |
| /// Printer pass for \c PredicateInfo. |
| class PredicateInfoPrinterPass |
| : public PassInfoMixin<PredicateInfoPrinterPass> { |
| raw_ostream &OS; |
| |
| public: |
| explicit PredicateInfoPrinterPass(raw_ostream &OS) : OS(OS) {} |
| PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM); |
| }; |
| |
| /// Verifier pass for \c PredicateInfo. |
| struct PredicateInfoVerifierPass : PassInfoMixin<PredicateInfoVerifierPass> { |
| PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM); |
| }; |
| |
| } // end namespace llvm |
| |
| #endif // LLVM_TRANSFORMS_UTILS_PREDICATEINFO_H |