| //===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator -------*- 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 |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file declares a GenericLoopInfo instantiation for LLVM IR. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_ANALYSIS_LOOPINFO_H |
| #define LLVM_ANALYSIS_LOOPINFO_H |
| |
| #include "llvm/ADT/DenseMap.h" |
| #include "llvm/ADT/DenseSet.h" |
| #include "llvm/ADT/GraphTraits.h" |
| #include "llvm/ADT/SmallPtrSet.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/IR/CFG.h" |
| #include "llvm/IR/Instructions.h" |
| #include "llvm/IR/PassManager.h" |
| #include "llvm/Pass.h" |
| #include "llvm/Support/GenericLoopInfo.h" |
| #include <algorithm> |
| #include <optional> |
| #include <utility> |
| |
| namespace llvm { |
| |
| class DominatorTree; |
| class InductionDescriptor; |
| class Instruction; |
| class LoopInfo; |
| class Loop; |
| class MDNode; |
| class MemorySSAUpdater; |
| class ScalarEvolution; |
| class raw_ostream; |
| |
| // Implementation in Support/GenericLoopInfoImpl.h |
| extern template class LoopBase<BasicBlock, Loop>; |
| |
| /// Represents a single loop in the control flow graph. Note that not all SCCs |
| /// in the CFG are necessarily loops. |
| class LLVM_EXTERNAL_VISIBILITY Loop : public LoopBase<BasicBlock, Loop> { |
| public: |
| /// A range representing the start and end location of a loop. |
| class LocRange { |
| DebugLoc Start; |
| DebugLoc End; |
| |
| public: |
| LocRange() = default; |
| LocRange(DebugLoc Start) : Start(Start), End(Start) {} |
| LocRange(DebugLoc Start, DebugLoc End) |
| : Start(std::move(Start)), End(std::move(End)) {} |
| |
| const DebugLoc &getStart() const { return Start; } |
| const DebugLoc &getEnd() const { return End; } |
| |
| /// Check for null. |
| /// |
| explicit operator bool() const { return Start && End; } |
| }; |
| |
| /// Return true if the specified value is loop invariant. |
| bool isLoopInvariant(const Value *V) const; |
| |
| /// Return true if all the operands of the specified instruction are loop |
| /// invariant. |
| bool hasLoopInvariantOperands(const Instruction *I) const; |
| |
| /// If the given value is an instruction inside of the loop and it can be |
| /// hoisted, do so to make it trivially loop-invariant. |
| /// Return true if \c V is already loop-invariant, and false if \c V can't |
| /// be made loop-invariant. If \c V is made loop-invariant, \c Changed is |
| /// set to true. This function can be used as a slightly more aggressive |
| /// replacement for isLoopInvariant. |
| /// |
| /// If InsertPt is specified, it is the point to hoist instructions to. |
| /// If null, the terminator of the loop preheader is used. |
| /// |
| bool makeLoopInvariant(Value *V, bool &Changed, |
| Instruction *InsertPt = nullptr, |
| MemorySSAUpdater *MSSAU = nullptr, |
| ScalarEvolution *SE = nullptr) const; |
| |
| /// If the given instruction is inside of the loop and it can be hoisted, do |
| /// so to make it trivially loop-invariant. |
| /// Return true if \c I is already loop-invariant, and false if \c I can't |
| /// be made loop-invariant. If \c I is made loop-invariant, \c Changed is |
| /// set to true. This function can be used as a slightly more aggressive |
| /// replacement for isLoopInvariant. |
| /// |
| /// If InsertPt is specified, it is the point to hoist instructions to. |
| /// If null, the terminator of the loop preheader is used. |
| /// |
| bool makeLoopInvariant(Instruction *I, bool &Changed, |
| Instruction *InsertPt = nullptr, |
| MemorySSAUpdater *MSSAU = nullptr, |
| ScalarEvolution *SE = nullptr) const; |
| |
| /// Check to see if the loop has a canonical induction variable: an integer |
| /// recurrence that starts at 0 and increments by one each time through the |
| /// loop. If so, return the phi node that corresponds to it. |
| /// |
| /// The IndVarSimplify pass transforms loops to have a canonical induction |
| /// variable. |
| /// |
| PHINode *getCanonicalInductionVariable() const; |
| |
| /// Get the latch condition instruction. |
| ICmpInst *getLatchCmpInst() const; |
| |
| /// Obtain the unique incoming and back edge. Return false if they are |
| /// non-unique or the loop is dead; otherwise, return true. |
| bool getIncomingAndBackEdge(BasicBlock *&Incoming, |
| BasicBlock *&Backedge) const; |
| |
| /// Below are some utilities to get the loop guard, loop bounds and induction |
| /// variable, and to check if a given phinode is an auxiliary induction |
| /// variable, if the loop is guarded, and if the loop is canonical. |
| /// |
| /// Here is an example: |
| /// \code |
| /// for (int i = lb; i < ub; i+=step) |
| /// <loop body> |
| /// --- pseudo LLVMIR --- |
| /// beforeloop: |
| /// guardcmp = (lb < ub) |
| /// if (guardcmp) goto preheader; else goto afterloop |
| /// preheader: |
| /// loop: |
| /// i_1 = phi[{lb, preheader}, {i_2, latch}] |
| /// <loop body> |
| /// i_2 = i_1 + step |
| /// latch: |
| /// cmp = (i_2 < ub) |
| /// if (cmp) goto loop |
| /// exit: |
| /// afterloop: |
| /// \endcode |
| /// |
| /// - getBounds |
| /// - getInitialIVValue --> lb |
| /// - getStepInst --> i_2 = i_1 + step |
| /// - getStepValue --> step |
| /// - getFinalIVValue --> ub |
| /// - getCanonicalPredicate --> '<' |
| /// - getDirection --> Increasing |
| /// |
| /// - getInductionVariable --> i_1 |
| /// - isAuxiliaryInductionVariable(x) --> true if x == i_1 |
| /// - getLoopGuardBranch() |
| /// --> `if (guardcmp) goto preheader; else goto afterloop` |
| /// - isGuarded() --> true |
| /// - isCanonical --> false |
| struct LoopBounds { |
| /// Return the LoopBounds object if |
| /// - the given \p IndVar is an induction variable |
| /// - the initial value of the induction variable can be found |
| /// - the step instruction of the induction variable can be found |
| /// - the final value of the induction variable can be found |
| /// |
| /// Else std::nullopt. |
| static std::optional<Loop::LoopBounds> |
| getBounds(const Loop &L, PHINode &IndVar, ScalarEvolution &SE); |
| |
| /// Get the initial value of the loop induction variable. |
| Value &getInitialIVValue() const { return InitialIVValue; } |
| |
| /// Get the instruction that updates the loop induction variable. |
| Instruction &getStepInst() const { return StepInst; } |
| |
| /// Get the step that the loop induction variable gets updated by in each |
| /// loop iteration. Return nullptr if not found. |
| Value *getStepValue() const { return StepValue; } |
| |
| /// Get the final value of the loop induction variable. |
| Value &getFinalIVValue() const { return FinalIVValue; } |
| |
| /// Return the canonical predicate for the latch compare instruction, if |
| /// able to be calcuated. Else BAD_ICMP_PREDICATE. |
| /// |
| /// A predicate is considered as canonical if requirements below are all |
| /// satisfied: |
| /// 1. The first successor of the latch branch is the loop header |
| /// If not, inverse the predicate. |
| /// 2. One of the operands of the latch comparison is StepInst |
| /// If not, and |
| /// - if the current calcuated predicate is not ne or eq, flip the |
| /// predicate. |
| /// - else if the loop is increasing, return slt |
| /// (notice that it is safe to change from ne or eq to sign compare) |
| /// - else if the loop is decreasing, return sgt |
| /// (notice that it is safe to change from ne or eq to sign compare) |
| /// |
| /// Here is an example when both (1) and (2) are not satisfied: |
| /// \code |
| /// loop.header: |
| /// %iv = phi [%initialiv, %loop.preheader], [%inc, %loop.header] |
| /// %inc = add %iv, %step |
| /// %cmp = slt %iv, %finaliv |
| /// br %cmp, %loop.exit, %loop.header |
| /// loop.exit: |
| /// \endcode |
| /// - The second successor of the latch branch is the loop header instead |
| /// of the first successor (slt -> sge) |
| /// - The first operand of the latch comparison (%cmp) is the IndVar (%iv) |
| /// instead of the StepInst (%inc) (sge -> sgt) |
| /// |
| /// The predicate would be sgt if both (1) and (2) are satisfied. |
| /// getCanonicalPredicate() returns sgt for this example. |
| /// Note: The IR is not changed. |
| ICmpInst::Predicate getCanonicalPredicate() const; |
| |
| /// An enum for the direction of the loop |
| /// - for (int i = 0; i < ub; ++i) --> Increasing |
| /// - for (int i = ub; i > 0; --i) --> Descresing |
| /// - for (int i = x; i != y; i+=z) --> Unknown |
| enum class Direction { Increasing, Decreasing, Unknown }; |
| |
| /// Get the direction of the loop. |
| Direction getDirection() const; |
| |
| private: |
| LoopBounds(const Loop &Loop, Value &I, Instruction &SI, Value *SV, Value &F, |
| ScalarEvolution &SE) |
| : L(Loop), InitialIVValue(I), StepInst(SI), StepValue(SV), |
| FinalIVValue(F), SE(SE) {} |
| |
| const Loop &L; |
| |
| // The initial value of the loop induction variable |
| Value &InitialIVValue; |
| |
| // The instruction that updates the loop induction variable |
| Instruction &StepInst; |
| |
| // The value that the loop induction variable gets updated by in each loop |
| // iteration |
| Value *StepValue; |
| |
| // The final value of the loop induction variable |
| Value &FinalIVValue; |
| |
| ScalarEvolution &SE; |
| }; |
| |
| /// Return the struct LoopBounds collected if all struct members are found, |
| /// else std::nullopt. |
| std::optional<LoopBounds> getBounds(ScalarEvolution &SE) const; |
| |
| /// Return the loop induction variable if found, else return nullptr. |
| /// An instruction is considered as the loop induction variable if |
| /// - it is an induction variable of the loop; and |
| /// - it is used to determine the condition of the branch in the loop latch |
| /// |
| /// Note: the induction variable doesn't need to be canonical, i.e. starts at |
| /// zero and increments by one each time through the loop (but it can be). |
| PHINode *getInductionVariable(ScalarEvolution &SE) const; |
| |
| /// Get the loop induction descriptor for the loop induction variable. Return |
| /// true if the loop induction variable is found. |
| bool getInductionDescriptor(ScalarEvolution &SE, |
| InductionDescriptor &IndDesc) const; |
| |
| /// Return true if the given PHINode \p AuxIndVar is |
| /// - in the loop header |
| /// - not used outside of the loop |
| /// - incremented by a loop invariant step for each loop iteration |
| /// - step instruction opcode should be add or sub |
| /// Note: auxiliary induction variable is not required to be used in the |
| /// conditional branch in the loop latch. (but it can be) |
| bool isAuxiliaryInductionVariable(PHINode &AuxIndVar, |
| ScalarEvolution &SE) const; |
| |
| /// Return the loop guard branch, if it exists. |
| /// |
| /// This currently only works on simplified loop, as it requires a preheader |
| /// and a latch to identify the guard. It will work on loops of the form: |
| /// \code |
| /// GuardBB: |
| /// br cond1, Preheader, ExitSucc <== GuardBranch |
| /// Preheader: |
| /// br Header |
| /// Header: |
| /// ... |
| /// br Latch |
| /// Latch: |
| /// br cond2, Header, ExitBlock |
| /// ExitBlock: |
| /// br ExitSucc |
| /// ExitSucc: |
| /// \endcode |
| BranchInst *getLoopGuardBranch() const; |
| |
| /// Return true iff the loop is |
| /// - in simplify rotated form, and |
| /// - guarded by a loop guard branch. |
| bool isGuarded() const { return (getLoopGuardBranch() != nullptr); } |
| |
| /// Return true if the loop is in rotated form. |
| /// |
| /// This does not check if the loop was rotated by loop rotation, instead it |
| /// only checks if the loop is in rotated form (has a valid latch that exists |
| /// the loop). |
| bool isRotatedForm() const { |
| assert(!isInvalid() && "Loop not in a valid state!"); |
| BasicBlock *Latch = getLoopLatch(); |
| return Latch && isLoopExiting(Latch); |
| } |
| |
| /// Return true if the loop induction variable starts at zero and increments |
| /// by one each time through the loop. |
| bool isCanonical(ScalarEvolution &SE) const; |
| |
| /// Return true if the Loop is in LCSSA form. If \p IgnoreTokens is set to |
| /// true, token values defined inside loop are allowed to violate LCSSA form. |
| bool isLCSSAForm(const DominatorTree &DT, bool IgnoreTokens = true) const; |
| |
| /// Return true if this Loop and all inner subloops are in LCSSA form. If \p |
| /// IgnoreTokens is set to true, token values defined inside loop are allowed |
| /// to violate LCSSA form. |
| bool isRecursivelyLCSSAForm(const DominatorTree &DT, const LoopInfo &LI, |
| bool IgnoreTokens = true) const; |
| |
| /// Return true if the Loop is in the form that the LoopSimplify form |
| /// transforms loops to, which is sometimes called normal form. |
| bool isLoopSimplifyForm() const; |
| |
| /// Return true if the loop body is safe to clone in practice. |
| bool isSafeToClone() const; |
| |
| /// Returns true if the loop is annotated parallel. |
| /// |
| /// A parallel loop can be assumed to not contain any dependencies between |
| /// iterations by the compiler. That is, any loop-carried dependency checking |
| /// can be skipped completely when parallelizing the loop on the target |
| /// machine. Thus, if the parallel loop information originates from the |
| /// programmer, e.g. via the OpenMP parallel for pragma, it is the |
| /// programmer's responsibility to ensure there are no loop-carried |
| /// dependencies. The final execution order of the instructions across |
| /// iterations is not guaranteed, thus, the end result might or might not |
| /// implement actual concurrent execution of instructions across multiple |
| /// iterations. |
| bool isAnnotatedParallel() const; |
| |
| /// Return the llvm.loop loop id metadata node for this loop if it is present. |
| /// |
| /// If this loop contains the same llvm.loop metadata on each branch to the |
| /// header then the node is returned. If any latch instruction does not |
| /// contain llvm.loop or if multiple latches contain different nodes then |
| /// 0 is returned. |
| MDNode *getLoopID() const; |
| /// Set the llvm.loop loop id metadata for this loop. |
| /// |
| /// The LoopID metadata node will be added to each terminator instruction in |
| /// the loop that branches to the loop header. |
| /// |
| /// The LoopID metadata node should have one or more operands and the first |
| /// operand should be the node itself. |
| void setLoopID(MDNode *LoopID) const; |
| |
| /// Add llvm.loop.unroll.disable to this loop's loop id metadata. |
| /// |
| /// Remove existing unroll metadata and add unroll disable metadata to |
| /// indicate the loop has already been unrolled. This prevents a loop |
| /// from being unrolled more than is directed by a pragma if the loop |
| /// unrolling pass is run more than once (which it generally is). |
| void setLoopAlreadyUnrolled(); |
| |
| /// Add llvm.loop.mustprogress to this loop's loop id metadata. |
| void setLoopMustProgress(); |
| |
| void dump() const; |
| void dumpVerbose() const; |
| |
| /// Return the debug location of the start of this loop. |
| /// This looks for a BB terminating instruction with a known debug |
| /// location by looking at the preheader and header blocks. If it |
| /// cannot find a terminating instruction with location information, |
| /// it returns an unknown location. |
| DebugLoc getStartLoc() const; |
| |
| /// Return the source code span of the loop. |
| LocRange getLocRange() const; |
| |
| StringRef getName() const { |
| if (BasicBlock *Header = getHeader()) |
| if (Header->hasName()) |
| return Header->getName(); |
| return "<unnamed loop>"; |
| } |
| |
| private: |
| Loop() = default; |
| |
| friend class LoopInfoBase<BasicBlock, Loop>; |
| friend class LoopBase<BasicBlock, Loop>; |
| explicit Loop(BasicBlock *BB) : LoopBase<BasicBlock, Loop>(BB) {} |
| ~Loop() = default; |
| }; |
| |
| // Implementation in Support/GenericLoopInfoImpl.h |
| extern template class LoopInfoBase<BasicBlock, Loop>; |
| |
| class LoopInfo : public LoopInfoBase<BasicBlock, Loop> { |
| typedef LoopInfoBase<BasicBlock, Loop> BaseT; |
| |
| friend class LoopBase<BasicBlock, Loop>; |
| |
| void operator=(const LoopInfo &) = delete; |
| LoopInfo(const LoopInfo &) = delete; |
| |
| public: |
| LoopInfo() = default; |
| explicit LoopInfo(const DominatorTreeBase<BasicBlock, false> &DomTree); |
| |
| LoopInfo(LoopInfo &&Arg) : BaseT(std::move(static_cast<BaseT &>(Arg))) {} |
| LoopInfo &operator=(LoopInfo &&RHS) { |
| BaseT::operator=(std::move(static_cast<BaseT &>(RHS))); |
| return *this; |
| } |
| |
| /// Handle invalidation explicitly. |
| bool invalidate(Function &F, const PreservedAnalyses &PA, |
| FunctionAnalysisManager::Invalidator &); |
| |
| // Most of the public interface is provided via LoopInfoBase. |
| |
| /// Update LoopInfo after removing the last backedge from a loop. This updates |
| /// the loop forest and parent loops for each block so that \c L is no longer |
| /// referenced, but does not actually delete \c L immediately. The pointer |
| /// will remain valid until this LoopInfo's memory is released. |
| void erase(Loop *L); |
| |
| /// Returns true if replacing From with To everywhere is guaranteed to |
| /// preserve LCSSA form. |
| bool replacementPreservesLCSSAForm(Instruction *From, Value *To) { |
| // Preserving LCSSA form is only problematic if the replacing value is an |
| // instruction. |
| Instruction *I = dyn_cast<Instruction>(To); |
| if (!I) |
| return true; |
| // If both instructions are defined in the same basic block then replacement |
| // cannot break LCSSA form. |
| if (I->getParent() == From->getParent()) |
| return true; |
| // If the instruction is not defined in a loop then it can safely replace |
| // anything. |
| Loop *ToLoop = getLoopFor(I->getParent()); |
| if (!ToLoop) |
| return true; |
| // If the replacing instruction is defined in the same loop as the original |
| // instruction, or in a loop that contains it as an inner loop, then using |
| // it as a replacement will not break LCSSA form. |
| return ToLoop->contains(getLoopFor(From->getParent())); |
| } |
| |
| /// Checks if moving a specific instruction can break LCSSA in any loop. |
| /// |
| /// Return true if moving \p Inst to before \p NewLoc will break LCSSA, |
| /// assuming that the function containing \p Inst and \p NewLoc is currently |
| /// in LCSSA form. |
| bool movementPreservesLCSSAForm(Instruction *Inst, Instruction *NewLoc) { |
| assert(Inst->getFunction() == NewLoc->getFunction() && |
| "Can't reason about IPO!"); |
| |
| auto *OldBB = Inst->getParent(); |
| auto *NewBB = NewLoc->getParent(); |
| |
| // Movement within the same loop does not break LCSSA (the equality check is |
| // to avoid doing a hashtable lookup in case of intra-block movement). |
| if (OldBB == NewBB) |
| return true; |
| |
| auto *OldLoop = getLoopFor(OldBB); |
| auto *NewLoop = getLoopFor(NewBB); |
| |
| if (OldLoop == NewLoop) |
| return true; |
| |
| // Check if Outer contains Inner; with the null loop counting as the |
| // "outermost" loop. |
| auto Contains = [](const Loop *Outer, const Loop *Inner) { |
| return !Outer || Outer->contains(Inner); |
| }; |
| |
| // To check that the movement of Inst to before NewLoc does not break LCSSA, |
| // we need to check two sets of uses for possible LCSSA violations at |
| // NewLoc: the users of NewInst, and the operands of NewInst. |
| |
| // If we know we're hoisting Inst out of an inner loop to an outer loop, |
| // then the uses *of* Inst don't need to be checked. |
| |
| if (!Contains(NewLoop, OldLoop)) { |
| for (Use &U : Inst->uses()) { |
| auto *UI = cast<Instruction>(U.getUser()); |
| auto *UBB = isa<PHINode>(UI) ? cast<PHINode>(UI)->getIncomingBlock(U) |
| : UI->getParent(); |
| if (UBB != NewBB && getLoopFor(UBB) != NewLoop) |
| return false; |
| } |
| } |
| |
| // If we know we're sinking Inst from an outer loop into an inner loop, then |
| // the *operands* of Inst don't need to be checked. |
| |
| if (!Contains(OldLoop, NewLoop)) { |
| // See below on why we can't handle phi nodes here. |
| if (isa<PHINode>(Inst)) |
| return false; |
| |
| for (Use &U : Inst->operands()) { |
| auto *DefI = dyn_cast<Instruction>(U.get()); |
| if (!DefI) |
| return false; |
| |
| // This would need adjustment if we allow Inst to be a phi node -- the |
| // new use block won't simply be NewBB. |
| |
| auto *DefBlock = DefI->getParent(); |
| if (DefBlock != NewBB && getLoopFor(DefBlock) != NewLoop) |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| |
| // Return true if a new use of V added in ExitBB would require an LCSSA PHI |
| // to be inserted at the begining of the block. Note that V is assumed to |
| // dominate ExitBB, and ExitBB must be the exit block of some loop. The |
| // IR is assumed to be in LCSSA form before the planned insertion. |
| bool wouldBeOutOfLoopUseRequiringLCSSA(const Value *V, |
| const BasicBlock *ExitBB) const; |
| }; |
| |
| /// Enable verification of loop info. |
| /// |
| /// The flag enables checks which are expensive and are disabled by default |
| /// unless the `EXPENSIVE_CHECKS` macro is defined. The `-verify-loop-info` |
| /// flag allows the checks to be enabled selectively without re-compilation. |
| extern bool VerifyLoopInfo; |
| |
| // Allow clients to walk the list of nested loops... |
| template <> struct GraphTraits<const Loop *> { |
| typedef const Loop *NodeRef; |
| typedef LoopInfo::iterator ChildIteratorType; |
| |
| static NodeRef getEntryNode(const Loop *L) { return L; } |
| static ChildIteratorType child_begin(NodeRef N) { return N->begin(); } |
| static ChildIteratorType child_end(NodeRef N) { return N->end(); } |
| }; |
| |
| template <> struct GraphTraits<Loop *> { |
| typedef Loop *NodeRef; |
| typedef LoopInfo::iterator ChildIteratorType; |
| |
| static NodeRef getEntryNode(Loop *L) { return L; } |
| static ChildIteratorType child_begin(NodeRef N) { return N->begin(); } |
| static ChildIteratorType child_end(NodeRef N) { return N->end(); } |
| }; |
| |
| /// Analysis pass that exposes the \c LoopInfo for a function. |
| class LoopAnalysis : public AnalysisInfoMixin<LoopAnalysis> { |
| friend AnalysisInfoMixin<LoopAnalysis>; |
| static AnalysisKey Key; |
| |
| public: |
| typedef LoopInfo Result; |
| |
| LoopInfo run(Function &F, FunctionAnalysisManager &AM); |
| }; |
| |
| /// Printer pass for the \c LoopAnalysis results. |
| class LoopPrinterPass : public PassInfoMixin<LoopPrinterPass> { |
| raw_ostream &OS; |
| |
| public: |
| explicit LoopPrinterPass(raw_ostream &OS) : OS(OS) {} |
| PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM); |
| }; |
| |
| /// Verifier pass for the \c LoopAnalysis results. |
| struct LoopVerifierPass : public PassInfoMixin<LoopVerifierPass> { |
| PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM); |
| }; |
| |
| /// The legacy pass manager's analysis pass to compute loop information. |
| class LoopInfoWrapperPass : public FunctionPass { |
| LoopInfo LI; |
| |
| public: |
| static char ID; // Pass identification, replacement for typeid |
| |
| LoopInfoWrapperPass(); |
| |
| LoopInfo &getLoopInfo() { return LI; } |
| const LoopInfo &getLoopInfo() const { return LI; } |
| |
| /// Calculate the natural loop information for a given function. |
| bool runOnFunction(Function &F) override; |
| |
| void verifyAnalysis() const override; |
| |
| void releaseMemory() override { LI.releaseMemory(); } |
| |
| void print(raw_ostream &O, const Module *M = nullptr) const override; |
| |
| void getAnalysisUsage(AnalysisUsage &AU) const override; |
| }; |
| |
| /// Function to print a loop's contents as LLVM's text IR assembly. |
| void printLoop(Loop &L, raw_ostream &OS, const std::string &Banner = ""); |
| |
| /// Find and return the loop attribute node for the attribute @p Name in |
| /// @p LoopID. Return nullptr if there is no such attribute. |
| MDNode *findOptionMDForLoopID(MDNode *LoopID, StringRef Name); |
| |
| /// Find string metadata for a loop. |
| /// |
| /// Returns the MDNode where the first operand is the metadata's name. The |
| /// following operands are the metadata's values. If no metadata with @p Name is |
| /// found, return nullptr. |
| MDNode *findOptionMDForLoop(const Loop *TheLoop, StringRef Name); |
| |
| std::optional<bool> getOptionalBoolLoopAttribute(const Loop *TheLoop, |
| StringRef Name); |
| |
| /// Returns true if Name is applied to TheLoop and enabled. |
| bool getBooleanLoopAttribute(const Loop *TheLoop, StringRef Name); |
| |
| /// Find named metadata for a loop with an integer value. |
| std::optional<int> getOptionalIntLoopAttribute(const Loop *TheLoop, |
| StringRef Name); |
| |
| /// Find named metadata for a loop with an integer value. Return \p Default if |
| /// not set. |
| int getIntLoopAttribute(const Loop *TheLoop, StringRef Name, int Default = 0); |
| |
| /// Find string metadata for loop |
| /// |
| /// If it has a value (e.g. {"llvm.distribute", 1} return the value as an |
| /// operand or null otherwise. If the string metadata is not found return |
| /// Optional's not-a-value. |
| std::optional<const MDOperand *> findStringMetadataForLoop(const Loop *TheLoop, |
| StringRef Name); |
| |
| /// Look for the loop attribute that requires progress within the loop. |
| /// Note: Most consumers probably want "isMustProgress" which checks |
| /// the containing function attribute too. |
| bool hasMustProgress(const Loop *L); |
| |
| /// Return true if this loop can be assumed to make progress. (i.e. can't |
| /// be infinite without side effects without also being undefined) |
| bool isMustProgress(const Loop *L); |
| |
| /// Return true if this loop can be assumed to run for a finite number of |
| /// iterations. |
| bool isFinite(const Loop *L); |
| |
| /// Return whether an MDNode might represent an access group. |
| /// |
| /// Access group metadata nodes have to be distinct and empty. Being |
| /// always-empty ensures that it never needs to be changed (which -- because |
| /// MDNodes are designed immutable -- would require creating a new MDNode). Note |
| /// that this is not a sufficient condition: not every distinct and empty NDNode |
| /// is representing an access group. |
| bool isValidAsAccessGroup(MDNode *AccGroup); |
| |
| /// Create a new LoopID after the loop has been transformed. |
| /// |
| /// This can be used when no follow-up loop attributes are defined |
| /// (llvm::makeFollowupLoopID returning None) to stop transformations to be |
| /// applied again. |
| /// |
| /// @param Context The LLVMContext in which to create the new LoopID. |
| /// @param OrigLoopID The original LoopID; can be nullptr if the original |
| /// loop has no LoopID. |
| /// @param RemovePrefixes Remove all loop attributes that have these prefixes. |
| /// Use to remove metadata of the transformation that has |
| /// been applied. |
| /// @param AddAttrs Add these loop attributes to the new LoopID. |
| /// |
| /// @return A new LoopID that can be applied using Loop::setLoopID(). |
| llvm::MDNode * |
| makePostTransformationMetadata(llvm::LLVMContext &Context, MDNode *OrigLoopID, |
| llvm::ArrayRef<llvm::StringRef> RemovePrefixes, |
| llvm::ArrayRef<llvm::MDNode *> AddAttrs); |
| |
| } // namespace llvm |
| |
| #endif |