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
24namespace llvm {
25class BasicBlock;
26class Instruction;
27class MDNode;
28} // end namespace llvm
29
30namespace clang {
31class Attr;
32class ASTContext;
33namespace CodeGen {
34
35/// \brief Attributes that may be specified on loops.
36struct 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.
63class LoopInfo {
64public:
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.
69  llvm::MDNode *getLoopID() const { return LoopID; }
70
71  /// \brief Get the header block of this loop.
72  llvm::BasicBlock *getHeader() const { return Header; }
73
74  /// \brief Get the set of attributes active for this loop.
75  const LoopAttributes &getAttributes() const { return Attrs; }
76
77private:
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.
89class LoopInfoStack {
90  LoopInfoStack(const LoopInfoStack &) = delete;
91  void operator=(const LoopInfoStack &) = delete;
92
93public:
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.
109  llvm::MDNode *getCurLoopID() const { return getInfo().getLoopID(); }
110
111  /// \brief Return true if the top loop is parallel.
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.
130  void setUnrollState(const LoopAttributes::LVEnableState &State) {
131    StagedAttrs.UnrollEnable = State;
132  }
133
134  /// \brief Set the vectorize width for the next loop pushed.
135  void setVectorizeWidth(unsigned W) { StagedAttrs.VectorizeWidth = W; }
136
137  /// \brief Set the interleave count for the next loop pushed.
138  void setInterleaveCount(unsigned C) { StagedAttrs.InterleaveCount = C; }
139
140  /// \brief Set the unroll count for the next loop pushed.
141  void setUnrollCount(unsigned C) { StagedAttrs.UnrollCount = C; }
142
143private:
144  /// \brief Returns true if there is LoopInfo on the stack.
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.
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