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/DebugLoc.h"
22#include "llvm/IR/Value.h"
23#include "llvm/Support/Compiler.h"
24
25namespace llvm {
26class BasicBlock;
27class Instruction;
28class MDNode;
29} // end namespace llvm
30
31namespace clang {
32class Attr;
33class ASTContext;
34namespace CodeGen {
35
36/// \brief Attributes that may be specified on loops.
37struct LoopAttributes {
38  explicit LoopAttributes(bool IsParallel = false);
39  void clear();
40
41  /// \brief Generate llvm.loop.parallel metadata for loads and stores.
42  bool IsParallel;
43
44  /// \brief State of loop vectorization or unrolling.
45  enum LVEnableState { Unspecified, Enable, Disable, Full };
46
47  /// \brief Value for llvm.loop.vectorize.enable metadata.
48  LVEnableState VectorizeEnable;
49
50  /// \brief Value for llvm.loop.unroll.* metadata (enable, disable, or full).
51  LVEnableState UnrollEnable;
52
53  /// \brief Value for llvm.loop.vectorize.width metadata.
54  unsigned VectorizeWidth;
55
56  /// \brief Value for llvm.loop.interleave.count metadata.
57  unsigned InterleaveCount;
58
59  /// \brief llvm.unroll.
60  unsigned UnrollCount;
61
62  /// \brief Value for llvm.loop.distribute.enable metadata.
63  LVEnableState DistributeEnable;
64};
65
66/// \brief Information used when generating a structured loop.
67class LoopInfo {
68public:
69  /// \brief Construct a new LoopInfo for the loop with entry Header.
70  LoopInfo(llvm::BasicBlock *Header, const LoopAttributes &Attrs,
71           llvm::DebugLoc Location);
72
73  /// \brief Get the loop id metadata for this loop.
74  llvm::MDNode *getLoopID() const { return LoopID; }
75
76  /// \brief Get the header block of this loop.
77  llvm::BasicBlock *getHeader() const { return Header; }
78
79  /// \brief Get the set of attributes active for this loop.
80  const LoopAttributes &getAttributes() const { return Attrs; }
81
82private:
83  /// \brief Loop ID metadata.
84  llvm::MDNode *LoopID;
85  /// \brief Header block of this loop.
86  llvm::BasicBlock *Header;
87  /// \brief The attributes for this loop.
88  LoopAttributes Attrs;
89};
90
91/// \brief A stack of loop information corresponding to loop nesting levels.
92/// This stack can be used to prepare attributes which are applied when a loop
93/// is emitted.
94class LoopInfoStack {
95  LoopInfoStack(const LoopInfoStack &) = delete;
96  void operator=(const LoopInfoStack &) = delete;
97
98public:
99  LoopInfoStack() {}
100
101  /// \brief Begin a new structured loop. The set of staged attributes will be
102  /// applied to the loop and then cleared.
103  void push(llvm::BasicBlock *Header,
104            llvm::DebugLoc Location = llvm::DebugLoc());
105
106  /// \brief Begin a new structured loop. Stage attributes from the Attrs list.
107  /// The staged attributes are applied to the loop and then cleared.
108  void push(llvm::BasicBlock *Header, clang::ASTContext &Ctx,
109            llvm::ArrayRef<const Attr *> Attrs,
110            llvm::DebugLoc Location = llvm::DebugLoc());
111
112  /// \brief End the current loop.
113  void pop();
114
115  /// \brief Return the top loop id metadata.
116  llvm::MDNode *getCurLoopID() const { return getInfo().getLoopID(); }
117
118  /// \brief Return true if the top loop is parallel.
119  bool getCurLoopParallel() const {
120    return hasInfo() ? getInfo().getAttributes().IsParallel : false;
121  }
122
123  /// \brief Function called by the CodeGenFunction when an instruction is
124  /// created.
125  void InsertHelper(llvm::Instruction *I) const;
126
127  /// \brief Set the next pushed loop as parallel.
128  void setParallel(bool Enable = true) { StagedAttrs.IsParallel = Enable; }
129
130  /// \brief Set the next pushed loop 'vectorize.enable'
131  void setVectorizeEnable(bool Enable = true) {
132    StagedAttrs.VectorizeEnable =
133        Enable ? LoopAttributes::Enable : LoopAttributes::Disable;
134  }
135
136  /// \brief Set the next pushed loop as a distribution candidate.
137  void setDistributeState(bool Enable = true) {
138    StagedAttrs.DistributeEnable =
139        Enable ? LoopAttributes::Enable : LoopAttributes::Disable;
140  }
141
142  /// \brief Set the next pushed loop unroll state.
143  void setUnrollState(const LoopAttributes::LVEnableState &State) {
144    StagedAttrs.UnrollEnable = State;
145  }
146
147  /// \brief Set the vectorize width for the next loop pushed.
148  void setVectorizeWidth(unsigned W) { StagedAttrs.VectorizeWidth = W; }
149
150  /// \brief Set the interleave count for the next loop pushed.
151  void setInterleaveCount(unsigned C) { StagedAttrs.InterleaveCount = C; }
152
153  /// \brief Set the unroll count for the next loop pushed.
154  void setUnrollCount(unsigned C) { StagedAttrs.UnrollCount = C; }
155
156private:
157  /// \brief Returns true if there is LoopInfo on the stack.
158  bool hasInfo() const { return !Active.empty(); }
159  /// \brief Return the LoopInfo for the current loop. HasInfo should be called
160  /// first to ensure LoopInfo is present.
161  const LoopInfo &getInfo() const { return Active.back(); }
162  /// \brief The set of attributes that will be applied to the next pushed loop.
163  LoopAttributes StagedAttrs;
164  /// \brief Stack of active loops.
165  llvm::SmallVector<LoopInfo, 4> Active;
166};
167
168} // end namespace CodeGen
169} // end namespace clang
170
171#endif
172