//===---- CGLoopInfo.h - LLVM CodeGen for loop metadata -*- 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 is the internal state used for llvm translation for loop statement

// metadata.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_LIB_CODEGEN_CGLOOPINFO_H

#define LLVM_CLANG_LIB_CODEGEN_CGLOOPINFO_H

#include "llvm/ADT/ArrayRef.h"

#include "llvm/ADT/SmallVector.h"

#include "llvm/IR/DebugLoc.h"

#include "llvm/IR/Value.h"

#include "llvm/Support/Compiler.h"

namespace llvm {

class BasicBlock;

class Instruction;

class MDNode;

} // end namespace llvm

namespace clang {

class Attr;

class ASTContext;

class CodeGenOptions;

namespace CodeGen {

/// Attributes that may be specified on loops.

struct LoopAttributes {

  explicit LoopAttributes(bool IsParallel = false);

  void clear();

  /// Generate llvm.loop.parallel metadata for loads and stores.

  bool IsParallel;

  /// State of loop vectorization or unrolling.

  enum LVEnableState { Unspecified, Enable, Disable, Full };

  /// Value for llvm.loop.vectorize.enable metadata.

  LVEnableState VectorizeEnable;

  /// Value for llvm.loop.unroll.* metadata (enable, disable, or full).

  LVEnableState UnrollEnable;

  /// Value for llvm.loop.unroll_and_jam.* metadata (enable, disable, or full).

  LVEnableState UnrollAndJamEnable;

  /// Value for llvm.loop.vectorize.predicate metadata

  LVEnableState VectorizePredicateEnable;

  /// Value for llvm.loop.vectorize.width metadata.

  unsigned VectorizeWidth;

  // Value for llvm.loop.vectorize.scalable.enable

  LVEnableState VectorizeScalable;

  /// Value for llvm.loop.interleave.count metadata.

  unsigned InterleaveCount;

  /// llvm.unroll.

  unsigned UnrollCount;

  /// llvm.unroll.

  unsigned UnrollAndJamCount;

  /// Value for llvm.loop.distribute.enable metadata.

  LVEnableState DistributeEnable;

  /// Value for llvm.loop.pipeline.disable metadata.

  bool PipelineDisabled;

  /// Value for llvm.loop.pipeline.iicount metadata.

  unsigned PipelineInitiationInterval;

  /// Value for 'llvm.loop.align' metadata.

  unsigned CodeAlign;

  /// Value for whether the loop is required to make progress.

  bool MustProgress;

};

/// Information used when generating a structured loop.

class LoopInfo {

public:

  /// Construct a new LoopInfo for the loop with entry Header.

  LoopInfo(llvm::BasicBlock *Header, const LoopAttributes &Attrs,

           const llvm::DebugLoc &StartLoc, const llvm::DebugLoc &EndLoc,

           LoopInfo *Parent);

  /// Get the loop id metadata for this loop.

  llvm::MDNode *getLoopID() const { return TempLoopID.get(); }

  /// Get the header block of this loop.

  llvm::BasicBlock *getHeader() const { return Header; }

  /// Get the set of attributes active for this loop.

  const LoopAttributes &getAttributes() const { return Attrs; }

  /// Return this loop's access group or nullptr if it does not have one.

  llvm::MDNode *getAccessGroup() const { return AccGroup; }

  /// Create the loop's metadata. Must be called after its nested loops have

  /// been processed.

  void finish();

private:

  /// Loop ID metadata.

  llvm::TempMDTuple TempLoopID;

  /// Header block of this loop.

  llvm::BasicBlock *Header;

  /// The attributes for this loop.

  LoopAttributes Attrs;

  /// The access group for memory accesses parallel to this loop.

  llvm::MDNode *AccGroup = nullptr;

  /// Start location of this loop.

  llvm::DebugLoc StartLoc;

  /// End location of this loop.

  llvm::DebugLoc EndLoc;

  /// The next outer loop, or nullptr if this is the outermost loop.

  LoopInfo *Parent;

  /// If this loop has unroll-and-jam metadata, this can be set by the inner

  /// loop's LoopInfo to set the llvm.loop.unroll_and_jam.followup_inner

  /// metadata.

  llvm::MDNode *UnrollAndJamInnerFollowup = nullptr;

  /// Create a LoopID without any transformations.

  llvm::MDNode *

  createLoopPropertiesMetadata(llvm::ArrayRef<llvm::Metadata *> LoopProperties);

  /// Create a LoopID for transformations.

  ///

  /// The methods call each other in case multiple transformations are applied

  /// to a loop. The transformation first to be applied will use LoopID of the

  /// next transformation in its followup attribute.

  ///

  /// @param Attrs             The loop's transformations.

  /// @param LoopProperties    Non-transformation properties such as debug

  ///                          location, parallel accesses and disabled

  ///                          transformations. These are added to the returned

  ///                          LoopID.

  /// @param HasUserTransforms [out] Set to true if the returned MDNode encodes

  ///                          at least one transformation.

  ///

  /// @return A LoopID (metadata node) that can be used for the llvm.loop

  ///         annotation or followup-attribute.

  /// @{

  llvm::MDNode *

  createPipeliningMetadata(const LoopAttributes &Attrs,

                           llvm::ArrayRef<llvm::Metadata *> LoopProperties,

                           bool &HasUserTransforms);

  llvm::MDNode *

  createPartialUnrollMetadata(const LoopAttributes &Attrs,

                              llvm::ArrayRef<llvm::Metadata *> LoopProperties,

                              bool &HasUserTransforms);

  llvm::MDNode *

  createUnrollAndJamMetadata(const LoopAttributes &Attrs,

                             llvm::ArrayRef<llvm::Metadata *> LoopProperties,

                             bool &HasUserTransforms);

  llvm::MDNode *

  createLoopVectorizeMetadata(const LoopAttributes &Attrs,

                              llvm::ArrayRef<llvm::Metadata *> LoopProperties,

                              bool &HasUserTransforms);

  llvm::MDNode *

  createLoopDistributeMetadata(const LoopAttributes &Attrs,

                               llvm::ArrayRef<llvm::Metadata *> LoopProperties,

                               bool &HasUserTransforms);

  llvm::MDNode *

  createFullUnrollMetadata(const LoopAttributes &Attrs,

                           llvm::ArrayRef<llvm::Metadata *> LoopProperties,

                           bool &HasUserTransforms);

  /// @}

  /// Create a LoopID for this loop, including transformation-unspecific

  /// metadata such as debug location.

  ///

  /// @param Attrs             This loop's attributes and transformations.

  /// @param LoopProperties    Additional non-transformation properties to add

  ///                          to the LoopID, such as transformation-specific

  ///                          metadata that are not covered by @p Attrs.

  /// @param HasUserTransforms [out] Set to true if the returned MDNode encodes

  ///                          at least one transformation.

  ///

  /// @return A LoopID (metadata node) that can be used for the llvm.loop

  ///         annotation.

  llvm::MDNode *createMetadata(const LoopAttributes &Attrs,

                               llvm::ArrayRef<llvm::Metadata *> LoopProperties,

                               bool &HasUserTransforms);

};

/// A stack of loop information corresponding to loop nesting levels.

/// This stack can be used to prepare attributes which are applied when a loop

/// is emitted.

class LoopInfoStack {

  LoopInfoStack(const LoopInfoStack &) = delete;

  void operator=(const LoopInfoStack &) = delete;

public:

  LoopInfoStack() {}

  /// Begin a new structured loop. The set of staged attributes will be

  /// applied to the loop and then cleared.

  void push(llvm::BasicBlock *Header, const llvm::DebugLoc &StartLoc,

            const llvm::DebugLoc &EndLoc);

  /// Begin a new structured loop. Stage attributes from the Attrs list.

  /// The staged attributes are applied to the loop and then cleared.

  void push(llvm::BasicBlock *Header, clang::ASTContext &Ctx,

            const clang::CodeGenOptions &CGOpts,

            llvm::ArrayRef<const Attr *> Attrs, const llvm::DebugLoc &StartLoc,

            const llvm::DebugLoc &EndLoc, bool MustProgress = false);

  /// End the current loop.

  void pop();

  /// Return the top loop id metadata.

  llvm::MDNode *getCurLoopID() const { return getInfo().getLoopID(); }

  /// Return true if the top loop is parallel.

  bool getCurLoopParallel() const {

    return hasInfo() ? getInfo().getAttributes().IsParallel : false;

  }

  /// Function called by the CodeGenFunction when an instruction is

  /// created.

  void InsertHelper(llvm::Instruction *I) const;

  /// Set the next pushed loop as parallel.

  void setParallel(bool Enable = true) { StagedAttrs.IsParallel = Enable; }

  /// Set the next pushed loop 'vectorize.enable'

  void setVectorizeEnable(bool Enable = true) {

    StagedAttrs.VectorizeEnable =

        Enable ? LoopAttributes::Enable : LoopAttributes::Disable;

  }

  /// Set the next pushed loop as a distribution candidate.

  void setDistributeState(bool Enable = true) {

    StagedAttrs.DistributeEnable =

        Enable ? LoopAttributes::Enable : LoopAttributes::Disable;

  }

  /// Set the next pushed loop unroll state.

  void setUnrollState(const LoopAttributes::LVEnableState &State) {

    StagedAttrs.UnrollEnable = State;

  }

  /// Set the next pushed vectorize predicate state.

  void setVectorizePredicateState(const LoopAttributes::LVEnableState &State) {

    StagedAttrs.VectorizePredicateEnable = State;

  }

  /// Set the next pushed loop unroll_and_jam state.

  void setUnrollAndJamState(const LoopAttributes::LVEnableState &State) {

    StagedAttrs.UnrollAndJamEnable = State;

  }

  /// Set the vectorize width for the next loop pushed.

  void setVectorizeWidth(unsigned W) { StagedAttrs.VectorizeWidth = W; }

  void setVectorizeScalable(const LoopAttributes::LVEnableState &State) {

    StagedAttrs.VectorizeScalable = State;

  }

  /// Set the interleave count for the next loop pushed.

  void setInterleaveCount(unsigned C) { StagedAttrs.InterleaveCount = C; }

  /// Set the unroll count for the next loop pushed.

  void setUnrollCount(unsigned C) { StagedAttrs.UnrollCount = C; }

  /// \brief Set the unroll count for the next loop pushed.

  void setUnrollAndJamCount(unsigned C) { StagedAttrs.UnrollAndJamCount = C; }

  /// Set the pipeline disabled state.

  void setPipelineDisabled(bool S) { StagedAttrs.PipelineDisabled = S; }

  /// Set the pipeline initiation interval.

  void setPipelineInitiationInterval(unsigned C) {

    StagedAttrs.PipelineInitiationInterval = C;

  }

  /// Set value of code align for the next loop pushed.

  void setCodeAlign(unsigned C) { StagedAttrs.CodeAlign = C; }

  /// Set no progress for the next loop pushed.

  void setMustProgress(bool P) { StagedAttrs.MustProgress = P; }

private:

  /// Returns true if there is LoopInfo on the stack.

  bool hasInfo() const { return !Active.empty(); }

  /// Return the LoopInfo for the current loop. HasInfo should be called

  /// first to ensure LoopInfo is present.

  const LoopInfo &getInfo() const { return *Active.back(); }

  /// The set of attributes that will be applied to the next pushed loop.

  LoopAttributes StagedAttrs;

  /// Stack of active loops.

  llvm::SmallVector<std::unique_ptr<LoopInfo>, 4> Active;

};

} // end namespace CodeGen

} // end namespace clang

#endif