clang/lib/CodeGen/CGLoopInfo.h

   1 //===---- CGLoopInfo.h - LLVM CodeGen for loop metadata -*- C++ -*---------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This is the internal state used for llvm translation for loop statement
  10 // metadata.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifndef LLVM_CLANG_LIB_CODEGEN_CGLOOPINFO_H
  15 #define LLVM_CLANG_LIB_CODEGEN_CGLOOPINFO_H
  16
  17 #include "llvm/ADT/ArrayRef.h"
  18 #include "llvm/ADT/SmallVector.h"
  19 #include "llvm/IR/DebugLoc.h"
  20 #include "llvm/IR/Value.h"
  21 #include "llvm/Support/Compiler.h"
  22
  23 namespace llvm {
  24 class BasicBlock;
  25 class Instruction;
  26 class MDNode;
  27 } // end namespace llvm
  28
  29 namespace clang {
  30 class Attr;
  31 class ASTContext;
  32 class CodeGenOptions;
  33 namespace CodeGen {
  34
  35 /// Attributes that may be specified on loops.
  36 struct LoopAttributes {
  37   explicit LoopAttributes(bool IsParallel = false);
  38   void clear();
  39
  40   /// Generate llvm.loop.parallel metadata for loads and stores.
  41   bool IsParallel;
  42
  43   /// State of loop vectorization or unrolling.
  44   enum LVEnableState { Unspecified, Enable, Disable, Full };
  45
  46   /// Value for llvm.loop.vectorize.enable metadata.
  47   LVEnableState VectorizeEnable;
  48
  49   /// Value for llvm.loop.unroll.* metadata (enable, disable, or full).
  50   LVEnableState UnrollEnable;
  51
  52   /// Value for llvm.loop.unroll_and_jam.* metadata (enable, disable, or full).
  53   LVEnableState UnrollAndJamEnable;
  54
  55   /// Value for llvm.loop.vectorize.predicate metadata
  56   LVEnableState VectorizePredicateEnable;
  57
  58   /// Value for llvm.loop.vectorize.width metadata.
  59   unsigned VectorizeWidth;
  60
  61   // Value for llvm.loop.vectorize.scalable.enable
  62   LVEnableState VectorizeScalable;
  63
  64   /// Value for llvm.loop.interleave.count metadata.
  65   unsigned InterleaveCount;
  66
  67   /// llvm.unroll.
  68   unsigned UnrollCount;
  69
  70   /// llvm.unroll.
  71   unsigned UnrollAndJamCount;
  72
  73   /// Value for llvm.loop.distribute.enable metadata.
  74   LVEnableState DistributeEnable;
  75
  76   /// Value for llvm.loop.pipeline.disable metadata.
  77   bool PipelineDisabled;
  78
  79   /// Value for llvm.loop.pipeline.iicount metadata.
  80   unsigned PipelineInitiationInterval;
  81
  82   /// Value for whether the loop is required to make progress.
  83   bool MustProgress;
  84 };
  85
  86 /// Information used when generating a structured loop.
  87 class LoopInfo {
  88 public:
  89   /// Construct a new LoopInfo for the loop with entry Header.
  90   LoopInfo(llvm::BasicBlock *Header, const LoopAttributes &Attrs,
  91            const llvm::DebugLoc &StartLoc, const llvm::DebugLoc &EndLoc,
  92            LoopInfo *Parent);
  93
  94   /// Get the loop id metadata for this loop.
  95   llvm::MDNode *getLoopID() const { return TempLoopID.get(); }
  96
  97   /// Get the header block of this loop.
  98   llvm::BasicBlock *getHeader() const { return Header; }
  99
 100   /// Get the set of attributes active for this loop.
 101   const LoopAttributes &getAttributes() const { return Attrs; }
 102
 103   /// Return this loop's access group or nullptr if it does not have one.
 104   llvm::MDNode *getAccessGroup() const { return AccGroup; }
 105
 106   /// Create the loop's metadata. Must be called after its nested loops have
 107   /// been processed.
 108   void finish();
 109
 110 private:
 111   /// Loop ID metadata.
 112   llvm::TempMDTuple TempLoopID;
 113   /// Header block of this loop.
 114   llvm::BasicBlock *Header;
 115   /// The attributes for this loop.
 116   LoopAttributes Attrs;
 117   /// The access group for memory accesses parallel to this loop.
 118   llvm::MDNode *AccGroup = nullptr;
 119   /// Start location of this loop.
 120   llvm::DebugLoc StartLoc;
 121   /// End location of this loop.
 122   llvm::DebugLoc EndLoc;
 123   /// The next outer loop, or nullptr if this is the outermost loop.
 124   LoopInfo *Parent;
 125   /// If this loop has unroll-and-jam metadata, this can be set by the inner
 126   /// loop's LoopInfo to set the llvm.loop.unroll_and_jam.followup_inner
 127   /// metadata.
 128   llvm::MDNode *UnrollAndJamInnerFollowup = nullptr;
 129
 130   /// Create a LoopID without any transformations.
 131   llvm::MDNode *
 132   createLoopPropertiesMetadata(llvm::ArrayRef<llvm::Metadata *> LoopProperties);
 133
 134   /// Create a LoopID for transformations.
 135   ///
 136   /// The methods call each other in case multiple transformations are applied
 137   /// to a loop. The transformation first to be applied will use LoopID of the
 138   /// next transformation in its followup attribute.
 139   ///
 140   /// @param Attrs             The loop's transformations.
 141   /// @param LoopProperties    Non-transformation properties such as debug
 142   ///                          location, parallel accesses and disabled
 143   ///                          transformations. These are added to the returned
 144   ///                          LoopID.
 145   /// @param HasUserTransforms [out] Set to true if the returned MDNode encodes
 146   ///                          at least one transformation.
 147   ///
 148   /// @return A LoopID (metadata node) that can be used for the llvm.loop
 149   ///         annotation or followup-attribute.
 150   /// @{
 151   llvm::MDNode *
 152   createPipeliningMetadata(const LoopAttributes &Attrs,
 153                            llvm::ArrayRef<llvm::Metadata *> LoopProperties,
 154                            bool &HasUserTransforms);
 155   llvm::MDNode *
 156   createPartialUnrollMetadata(const LoopAttributes &Attrs,
 157                               llvm::ArrayRef<llvm::Metadata *> LoopProperties,
 158                               bool &HasUserTransforms);
 159   llvm::MDNode *
 160   createUnrollAndJamMetadata(const LoopAttributes &Attrs,
 161                              llvm::ArrayRef<llvm::Metadata *> LoopProperties,
 162                              bool &HasUserTransforms);
 163   llvm::MDNode *
 164   createLoopVectorizeMetadata(const LoopAttributes &Attrs,
 165                               llvm::ArrayRef<llvm::Metadata *> LoopProperties,
 166                               bool &HasUserTransforms);
 167   llvm::MDNode *
 168   createLoopDistributeMetadata(const LoopAttributes &Attrs,
 169                                llvm::ArrayRef<llvm::Metadata *> LoopProperties,
 170                                bool &HasUserTransforms);
 171   llvm::MDNode *
 172   createFullUnrollMetadata(const LoopAttributes &Attrs,
 173                            llvm::ArrayRef<llvm::Metadata *> LoopProperties,
 174                            bool &HasUserTransforms);
 175   /// @}
 176
 177   /// Create a LoopID for this loop, including transformation-unspecific
 178   /// metadata such as debug location.
 179   ///
 180   /// @param Attrs             This loop's attributes and transformations.
 181   /// @param LoopProperties    Additional non-transformation properties to add
 182   ///                          to the LoopID, such as transformation-specific
 183   ///                          metadata that are not covered by @p Attrs.
 184   /// @param HasUserTransforms [out] Set to true if the returned MDNode encodes
 185   ///                          at least one transformation.
 186   ///
 187   /// @return A LoopID (metadata node) that can be used for the llvm.loop
 188   ///         annotation.
 189   llvm::MDNode *createMetadata(const LoopAttributes &Attrs,
 190                                llvm::ArrayRef<llvm::Metadata *> LoopProperties,
 191                                bool &HasUserTransforms);
 192 };
 193
 194 /// A stack of loop information corresponding to loop nesting levels.
 195 /// This stack can be used to prepare attributes which are applied when a loop
 196 /// is emitted.
 197 class LoopInfoStack {
 198   LoopInfoStack(const LoopInfoStack &) = delete;
 199   void operator=(const LoopInfoStack &) = delete;
 200
 201 public:
 202   LoopInfoStack() {}
 203
 204   /// Begin a new structured loop. The set of staged attributes will be
 205   /// applied to the loop and then cleared.
 206   void push(llvm::BasicBlock *Header, const llvm::DebugLoc &StartLoc,
 207             const llvm::DebugLoc &EndLoc);
 208
 209   /// Begin a new structured loop. Stage attributes from the Attrs list.
 210   /// The staged attributes are applied to the loop and then cleared.
 211   void push(llvm::BasicBlock *Header, clang::ASTContext &Ctx,
 212             const clang::CodeGenOptions &CGOpts,
 213             llvm::ArrayRef<const Attr *> Attrs, const llvm::DebugLoc &StartLoc,
 214             const llvm::DebugLoc &EndLoc, bool MustProgress = false);
 215
 216   /// End the current loop.
 217   void pop();
 218
 219   /// Return the top loop id metadata.
 220   llvm::MDNode *getCurLoopID() const { return getInfo().getLoopID(); }
 221
 222   /// Return true if the top loop is parallel.
 223   bool getCurLoopParallel() const {
 224     return hasInfo() ? getInfo().getAttributes().IsParallel : false;
 225   }
 226
 227   /// Function called by the CodeGenFunction when an instruction is
 228   /// created.
 229   void InsertHelper(llvm::Instruction *I) const;
 230
 231   /// Set the next pushed loop as parallel.
 232   void setParallel(bool Enable = true) { StagedAttrs.IsParallel = Enable; }
 233
 234   /// Set the next pushed loop 'vectorize.enable'
 235   void setVectorizeEnable(bool Enable = true) {
 236     StagedAttrs.VectorizeEnable =
 237         Enable ? LoopAttributes::Enable : LoopAttributes::Disable;
 238   }
 239
 240   /// Set the next pushed loop as a distribution candidate.
 241   void setDistributeState(bool Enable = true) {
 242     StagedAttrs.DistributeEnable =
 243         Enable ? LoopAttributes::Enable : LoopAttributes::Disable;
 244   }
 245
 246   /// Set the next pushed loop unroll state.
 247   void setUnrollState(const LoopAttributes::LVEnableState &State) {
 248     StagedAttrs.UnrollEnable = State;
 249   }
 250
 251   /// Set the next pushed vectorize predicate state.
 252   void setVectorizePredicateState(const LoopAttributes::LVEnableState &State) {
 253     StagedAttrs.VectorizePredicateEnable = State;
 254   }
 255
 256   /// Set the next pushed loop unroll_and_jam state.
 257   void setUnrollAndJamState(const LoopAttributes::LVEnableState &State) {
 258     StagedAttrs.UnrollAndJamEnable = State;
 259   }
 260
 261   /// Set the vectorize width for the next loop pushed.
 262   void setVectorizeWidth(unsigned W) { StagedAttrs.VectorizeWidth = W; }
 263
 264   void setVectorizeScalable(const LoopAttributes::LVEnableState &State) {
 265     StagedAttrs.VectorizeScalable = State;
 266   }
 267
 268   /// Set the interleave count for the next loop pushed.
 269   void setInterleaveCount(unsigned C) { StagedAttrs.InterleaveCount = C; }
 270
 271   /// Set the unroll count for the next loop pushed.
 272   void setUnrollCount(unsigned C) { StagedAttrs.UnrollCount = C; }
 273
 274   /// \brief Set the unroll count for the next loop pushed.
 275   void setUnrollAndJamCount(unsigned C) { StagedAttrs.UnrollAndJamCount = C; }
 276
 277   /// Set the pipeline disabled state.
 278   void setPipelineDisabled(bool S) { StagedAttrs.PipelineDisabled = S; }
 279
 280   /// Set the pipeline initiation interval.
 281   void setPipelineInitiationInterval(unsigned C) {
 282     StagedAttrs.PipelineInitiationInterval = C;
 283   }
 284
 285   /// Set no progress for the next loop pushed.
 286   void setMustProgress(bool P) { StagedAttrs.MustProgress = P; }
 287
 288 private:
 289   /// Returns true if there is LoopInfo on the stack.
 290   bool hasInfo() const { return !Active.empty(); }
 291   /// Return the LoopInfo for the current loop. HasInfo should be called
 292   /// first to ensure LoopInfo is present.
 293   const LoopInfo &getInfo() const { return *Active.back(); }
 294   /// The set of attributes that will be applied to the next pushed loop.
 295   LoopAttributes StagedAttrs;
 296   /// Stack of active loops.
 297   llvm::SmallVector<std::unique_ptr<LoopInfo>, 4> Active;
 298 };
 299
 300 } // end namespace CodeGen
 301 } // end namespace clang
 302
 303 #endif