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 LLVM_CLANG_LIB_CODEGEN_CGLOOPINFO_H
16 #define LLVM_CLANG_LIB_CODEGEN_CGLOOPINFO_H
17 
18 #include "llvm/ADT/ArrayRef.h"
19 #include "llvm/ADT/DenseMap.h"
20 #include "llvm/ADT/SmallVector.h"
21 #include "llvm/IR/Value.h"
22 #include "llvm/Support/Compiler.h"
23 
24 namespace llvm {
25 class BasicBlock;
26 class Instruction;
27 class MDNode;
28 } // end namespace llvm
29 
30 namespace clang {
31 class Attr;
32 class ASTContext;
33 namespace CodeGen {
34 
35 /// \brief Attributes that may be specified on loops.
36 struct LoopAttributes {
37   explicit LoopAttributes(bool IsParallel = false);
38   void clear();
39 
40   /// \brief Generate llvm.loop.parallel metadata for loads and stores.
41   bool IsParallel;
42 
43   /// \brief State of loop vectorization or unrolling.
44   enum LVEnableState { Unspecified, Enable, Disable, Full };
45 
46   /// \brief Value for llvm.loop.vectorize.enable metadata.
47   LVEnableState VectorizeEnable;
48 
49   /// \brief Value for llvm.loop.unroll.* metadata (enable, disable, or full).
50   LVEnableState UnrollEnable;
51 
52   /// \brief Value for llvm.loop.vectorize.width metadata.
53   unsigned VectorizeWidth;
54 
55   /// \brief Value for llvm.loop.interleave.count metadata.
56   unsigned InterleaveCount;
57 
58   /// \brief llvm.unroll.
59   unsigned UnrollCount;
60 };
61 
62 /// \brief Information used when generating a structured loop.
63 class LoopInfo {
64 public:
65   /// \brief Construct a new LoopInfo for the loop with entry Header.
66   LoopInfo(llvm::BasicBlock *Header, const LoopAttributes &Attrs);
67 
68   /// \brief Get the loop id metadata for this loop.
getLoopID()69   llvm::MDNode *getLoopID() const { return LoopID; }
70 
71   /// \brief Get the header block of this loop.
getHeader()72   llvm::BasicBlock *getHeader() const { return Header; }
73 
74   /// \brief Get the set of attributes active for this loop.
getAttributes()75   const LoopAttributes &getAttributes() const { return Attrs; }
76 
77 private:
78   /// \brief Loop ID metadata.
79   llvm::MDNode *LoopID;
80   /// \brief Header block of this loop.
81   llvm::BasicBlock *Header;
82   /// \brief The attributes for this loop.
83   LoopAttributes Attrs;
84 };
85 
86 /// \brief A stack of loop information corresponding to loop nesting levels.
87 /// This stack can be used to prepare attributes which are applied when a loop
88 /// is emitted.
89 class LoopInfoStack {
90   LoopInfoStack(const LoopInfoStack &) = delete;
91   void operator=(const LoopInfoStack &) = delete;
92 
93 public:
LoopInfoStack()94   LoopInfoStack() {}
95 
96   /// \brief Begin a new structured loop. The set of staged attributes will be
97   /// applied to the loop and then cleared.
98   void push(llvm::BasicBlock *Header);
99 
100   /// \brief Begin a new structured loop. Stage attributes from the Attrs list.
101   /// The staged attributes are applied to the loop and then cleared.
102   void push(llvm::BasicBlock *Header, clang::ASTContext &Ctx,
103             llvm::ArrayRef<const Attr *> Attrs);
104 
105   /// \brief End the current loop.
106   void pop();
107 
108   /// \brief Return the top loop id metadata.
getCurLoopID()109   llvm::MDNode *getCurLoopID() const { return getInfo().getLoopID(); }
110 
111   /// \brief Return true if the top loop is parallel.
getCurLoopParallel()112   bool getCurLoopParallel() const {
113     return hasInfo() ? getInfo().getAttributes().IsParallel : false;
114   }
115 
116   /// \brief Function called by the CodeGenFunction when an instruction is
117   /// created.
118   void InsertHelper(llvm::Instruction *I) const;
119 
120   /// \brief Set the next pushed loop as parallel.
121   void setParallel(bool Enable = true) { StagedAttrs.IsParallel = Enable; }
122 
123   /// \brief Set the next pushed loop 'vectorize.enable'
124   void setVectorizeEnable(bool Enable = true) {
125     StagedAttrs.VectorizeEnable =
126         Enable ? LoopAttributes::Enable : LoopAttributes::Disable;
127   }
128 
129   /// \brief Set the next pushed loop unroll state.
setUnrollState(const LoopAttributes::LVEnableState & State)130   void setUnrollState(const LoopAttributes::LVEnableState &State) {
131     StagedAttrs.UnrollEnable = State;
132   }
133 
134   /// \brief Set the vectorize width for the next loop pushed.
setVectorizeWidth(unsigned W)135   void setVectorizeWidth(unsigned W) { StagedAttrs.VectorizeWidth = W; }
136 
137   /// \brief Set the interleave count for the next loop pushed.
setInterleaveCount(unsigned C)138   void setInterleaveCount(unsigned C) { StagedAttrs.InterleaveCount = C; }
139 
140   /// \brief Set the unroll count for the next loop pushed.
setUnrollCount(unsigned C)141   void setUnrollCount(unsigned C) { StagedAttrs.UnrollCount = C; }
142 
143 private:
144   /// \brief Returns true if there is LoopInfo on the stack.
hasInfo()145   bool hasInfo() const { return !Active.empty(); }
146   /// \brief Return the LoopInfo for the current loop. HasInfo should be called
147   /// first to ensure LoopInfo is present.
getInfo()148   const LoopInfo &getInfo() const { return Active.back(); }
149   /// \brief The set of attributes that will be applied to the next pushed loop.
150   LoopAttributes StagedAttrs;
151   /// \brief Stack of active loops.
152   llvm::SmallVector<LoopInfo, 4> Active;
153 };
154 
155 } // end namespace CodeGen
156 } // end namespace clang
157 
158 #endif
159