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      1 //===---- CGLoopInfo.h - LLVM CodeGen for loop metadata -*- C++ -*---------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This is the internal state used for llvm translation for loop statement
     11 // metadata.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #ifndef CLANG_CODEGEN_CGLOOPINFO_H
     16 #define CLANG_CODEGEN_CGLOOPINFO_H
     17 
     18 #include "llvm/ADT/DenseMap.h"
     19 #include "llvm/ADT/SmallVector.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 namespace CodeGen {
     31 
     32 /// \brief Attributes that may be specified on loops.
     33 struct LoopAttributes {
     34   explicit LoopAttributes(bool IsParallel = false);
     35   void clear();
     36 
     37   /// \brief Generate llvm.loop.parallel metadata for loads and stores.
     38   bool IsParallel;
     39 
     40   /// \brief Values of llvm.loop.vectorize.enable metadata.
     41   enum LVEnableState { VecUnspecified, VecEnable, VecDisable };
     42 
     43   /// \brief llvm.loop.vectorize.enable
     44   LVEnableState VectorizerEnable;
     45 
     46   /// \brief llvm.loop.vectorize.width
     47   unsigned VectorizerWidth;
     48 
     49   /// \brief llvm.loop.vectorize.unroll
     50   unsigned VectorizerUnroll;
     51 };
     52 
     53 /// \brief Information used when generating a structured loop.
     54 class LoopInfo {
     55 public:
     56   /// \brief Construct a new LoopInfo for the loop with entry Header.
     57   LoopInfo(llvm::BasicBlock *Header, const LoopAttributes &Attrs);
     58 
     59   /// \brief Get the loop id metadata for this loop.
     60   llvm::MDNode *getLoopID() const { return LoopID; }
     61 
     62   /// \brief Get the header block of this loop.
     63   llvm::BasicBlock *getHeader() const { return Header; }
     64 
     65   /// \brief Get the set of attributes active for this loop.
     66   const LoopAttributes &getAttributes() const { return Attrs; }
     67 
     68 private:
     69   /// \brief Loop ID metadata.
     70   llvm::MDNode *LoopID;
     71   /// \brief Header block of this loop.
     72   llvm::BasicBlock *Header;
     73   /// \brief The attributes for this loop.
     74   LoopAttributes Attrs;
     75 };
     76 
     77 /// \brief A stack of loop information corresponding to loop nesting levels.
     78 /// This stack can be used to prepare attributes which are applied when a loop
     79 /// is emitted.
     80 class LoopInfoStack {
     81   LoopInfoStack(const LoopInfoStack &) LLVM_DELETED_FUNCTION;
     82   void operator=(const LoopInfoStack &) LLVM_DELETED_FUNCTION;
     83 
     84 public:
     85   LoopInfoStack() {}
     86 
     87   /// \brief Begin a new structured loop. The set of staged attributes will be
     88   /// applied to the loop and then cleared.
     89   void push(llvm::BasicBlock *Header);
     90 
     91   /// \brief End the current loop.
     92   void pop();
     93 
     94   /// \brief Return the top loop id metadata.
     95   llvm::MDNode *getCurLoopID() const { return getInfo().getLoopID(); }
     96 
     97   /// \brief Return true if the top loop is parallel.
     98   bool getCurLoopParallel() const {
     99     return hasInfo() ? getInfo().getAttributes().IsParallel : false;
    100   }
    101 
    102   /// \brief Function called by the CodeGenFunction when an instruction is
    103   /// created.
    104   void InsertHelper(llvm::Instruction *I) const;
    105 
    106   /// \brief Set the next pushed loop as parallel.
    107   void setParallel(bool Enable = true) { StagedAttrs.IsParallel = Enable; }
    108 
    109   /// \brief Set the next pushed loop 'vectorizer.enable'
    110   void setVectorizerEnable(bool Enable = true) {
    111     StagedAttrs.VectorizerEnable =
    112         Enable ? LoopAttributes::VecEnable : LoopAttributes::VecDisable;
    113   }
    114 
    115   /// \brief Set the vectorizer width for the next loop pushed.
    116   void setVectorizerWidth(unsigned W) { StagedAttrs.VectorizerWidth = W; }
    117 
    118   /// \brief Set the vectorizer unroll for the next loop pushed.
    119   void setVectorizerUnroll(unsigned U) { StagedAttrs.VectorizerUnroll = U; }
    120 
    121 private:
    122   /// \brief Returns true if there is LoopInfo on the stack.
    123   bool hasInfo() const { return !Active.empty(); }
    124   /// \brief Return the LoopInfo for the current loop. HasInfo should be called
    125   /// first to ensure LoopInfo is present.
    126   const LoopInfo &getInfo() const { return Active.back(); }
    127   /// \brief The set of attributes that will be applied to the next pushed loop.
    128   LoopAttributes StagedAttrs;
    129   /// \brief Stack of active loops.
    130   llvm::SmallVector<LoopInfo, 4> Active;
    131 };
    132 
    133 } // end namespace CodeGen
    134 } // end namespace clang
    135 
    136 #endif // CLANG_CODEGEN_CGLOOPINFO_H
    137