xref: /freebsd/contrib/llvm-project/clang/lib/CodeGen/CGLoopInfo.h (revision b51f459a2098622c31ed54f5c1bf0e03efce403b)
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.interleave.count metadata.
62   unsigned InterleaveCount;
63 
64   /// llvm.unroll.
65   unsigned UnrollCount;
66 
67   /// llvm.unroll.
68   unsigned UnrollAndJamCount;
69 
70   /// Value for llvm.loop.distribute.enable metadata.
71   LVEnableState DistributeEnable;
72 
73   /// Value for llvm.loop.pipeline.disable metadata.
74   bool PipelineDisabled;
75 
76   /// Value for llvm.loop.pipeline.iicount metadata.
77   unsigned PipelineInitiationInterval;
78 };
79 
80 /// Information used when generating a structured loop.
81 class LoopInfo {
82 public:
83   /// Construct a new LoopInfo for the loop with entry Header.
84   LoopInfo(llvm::BasicBlock *Header, const LoopAttributes &Attrs,
85            const llvm::DebugLoc &StartLoc, const llvm::DebugLoc &EndLoc,
86            LoopInfo *Parent);
87 
88   /// Get the loop id metadata for this loop.
89   llvm::MDNode *getLoopID() const { return TempLoopID.get(); }
90 
91   /// Get the header block of this loop.
92   llvm::BasicBlock *getHeader() const { return Header; }
93 
94   /// Get the set of attributes active for this loop.
95   const LoopAttributes &getAttributes() const { return Attrs; }
96 
97   /// Return this loop's access group or nullptr if it does not have one.
98   llvm::MDNode *getAccessGroup() const { return AccGroup; }
99 
100   /// Create the loop's metadata. Must be called after its nested loops have
101   /// been processed.
102   void finish();
103 
104 private:
105   /// Loop ID metadata.
106   llvm::TempMDTuple TempLoopID;
107   /// Header block of this loop.
108   llvm::BasicBlock *Header;
109   /// The attributes for this loop.
110   LoopAttributes Attrs;
111   /// The access group for memory accesses parallel to this loop.
112   llvm::MDNode *AccGroup = nullptr;
113   /// Start location of this loop.
114   llvm::DebugLoc StartLoc;
115   /// End location of this loop.
116   llvm::DebugLoc EndLoc;
117   /// The next outer loop, or nullptr if this is the outermost loop.
118   LoopInfo *Parent;
119   /// If this loop has unroll-and-jam metadata, this can be set by the inner
120   /// loop's LoopInfo to set the llvm.loop.unroll_and_jam.followup_inner
121   /// metadata.
122   llvm::MDNode *UnrollAndJamInnerFollowup = nullptr;
123 
124   /// Create a LoopID without any transformations.
125   llvm::MDNode *
126   createLoopPropertiesMetadata(llvm::ArrayRef<llvm::Metadata *> LoopProperties);
127 
128   /// Create a LoopID for transformations.
129   ///
130   /// The methods call each other in case multiple transformations are applied
131   /// to a loop. The transformation first to be applied will use LoopID of the
132   /// next transformation in its followup attribute.
133   ///
134   /// @param Attrs             The loop's transformations.
135   /// @param LoopProperties    Non-transformation properties such as debug
136   ///                          location, parallel accesses and disabled
137   ///                          transformations. These are added to the returned
138   ///                          LoopID.
139   /// @param HasUserTransforms [out] Set to true if the returned MDNode encodes
140   ///                          at least one transformation.
141   ///
142   /// @return A LoopID (metadata node) that can be used for the llvm.loop
143   ///         annotation or followup-attribute.
144   /// @{
145   llvm::MDNode *
146   createPipeliningMetadata(const LoopAttributes &Attrs,
147                            llvm::ArrayRef<llvm::Metadata *> LoopProperties,
148                            bool &HasUserTransforms);
149   llvm::MDNode *
150   createPartialUnrollMetadata(const LoopAttributes &Attrs,
151                               llvm::ArrayRef<llvm::Metadata *> LoopProperties,
152                               bool &HasUserTransforms);
153   llvm::MDNode *
154   createUnrollAndJamMetadata(const LoopAttributes &Attrs,
155                              llvm::ArrayRef<llvm::Metadata *> LoopProperties,
156                              bool &HasUserTransforms);
157   llvm::MDNode *
158   createLoopVectorizeMetadata(const LoopAttributes &Attrs,
159                               llvm::ArrayRef<llvm::Metadata *> LoopProperties,
160                               bool &HasUserTransforms);
161   llvm::MDNode *
162   createLoopDistributeMetadata(const LoopAttributes &Attrs,
163                                llvm::ArrayRef<llvm::Metadata *> LoopProperties,
164                                bool &HasUserTransforms);
165   llvm::MDNode *
166   createFullUnrollMetadata(const LoopAttributes &Attrs,
167                            llvm::ArrayRef<llvm::Metadata *> LoopProperties,
168                            bool &HasUserTransforms);
169   /// @}
170 
171   /// Create a LoopID for this loop, including transformation-unspecific
172   /// metadata such as debug location.
173   ///
174   /// @param Attrs             This loop's attributes and transformations.
175   /// @param LoopProperties    Additional non-transformation properties to add
176   ///                          to the LoopID, such as transformation-specific
177   ///                          metadata that are not covered by @p Attrs.
178   /// @param HasUserTransforms [out] Set to true if the returned MDNode encodes
179   ///                          at least one transformation.
180   ///
181   /// @return A LoopID (metadata node) that can be used for the llvm.loop
182   ///         annotation.
183   llvm::MDNode *createMetadata(const LoopAttributes &Attrs,
184                                llvm::ArrayRef<llvm::Metadata *> LoopProperties,
185                                bool &HasUserTransforms);
186 };
187 
188 /// A stack of loop information corresponding to loop nesting levels.
189 /// This stack can be used to prepare attributes which are applied when a loop
190 /// is emitted.
191 class LoopInfoStack {
192   LoopInfoStack(const LoopInfoStack &) = delete;
193   void operator=(const LoopInfoStack &) = delete;
194 
195 public:
196   LoopInfoStack() {}
197 
198   /// Begin a new structured loop. The set of staged attributes will be
199   /// applied to the loop and then cleared.
200   void push(llvm::BasicBlock *Header, const llvm::DebugLoc &StartLoc,
201             const llvm::DebugLoc &EndLoc);
202 
203   /// Begin a new structured loop. Stage attributes from the Attrs list.
204   /// The staged attributes are applied to the loop and then cleared.
205   void push(llvm::BasicBlock *Header, clang::ASTContext &Ctx,
206             const clang::CodeGenOptions &CGOpts,
207             llvm::ArrayRef<const Attr *> Attrs, const llvm::DebugLoc &StartLoc,
208             const llvm::DebugLoc &EndLoc);
209 
210   /// End the current loop.
211   void pop();
212 
213   /// Return the top loop id metadata.
214   llvm::MDNode *getCurLoopID() const { return getInfo().getLoopID(); }
215 
216   /// Return true if the top loop is parallel.
217   bool getCurLoopParallel() const {
218     return hasInfo() ? getInfo().getAttributes().IsParallel : false;
219   }
220 
221   /// Function called by the CodeGenFunction when an instruction is
222   /// created.
223   void InsertHelper(llvm::Instruction *I) const;
224 
225   /// Set the next pushed loop as parallel.
226   void setParallel(bool Enable = true) { StagedAttrs.IsParallel = Enable; }
227 
228   /// Set the next pushed loop 'vectorize.enable'
229   void setVectorizeEnable(bool Enable = true) {
230     StagedAttrs.VectorizeEnable =
231         Enable ? LoopAttributes::Enable : LoopAttributes::Disable;
232   }
233 
234   /// Set the next pushed loop as a distribution candidate.
235   void setDistributeState(bool Enable = true) {
236     StagedAttrs.DistributeEnable =
237         Enable ? LoopAttributes::Enable : LoopAttributes::Disable;
238   }
239 
240   /// Set the next pushed loop unroll state.
241   void setUnrollState(const LoopAttributes::LVEnableState &State) {
242     StagedAttrs.UnrollEnable = State;
243   }
244 
245   /// Set the next pushed vectorize predicate state.
246   void setVectorizePredicateState(const LoopAttributes::LVEnableState &State) {
247     StagedAttrs.VectorizePredicateEnable = State;
248   }
249 
250   /// Set the next pushed loop unroll_and_jam state.
251   void setUnrollAndJamState(const LoopAttributes::LVEnableState &State) {
252     StagedAttrs.UnrollAndJamEnable = State;
253   }
254 
255   /// Set the vectorize width for the next loop pushed.
256   void setVectorizeWidth(unsigned W) { StagedAttrs.VectorizeWidth = W; }
257 
258   /// Set the interleave count for the next loop pushed.
259   void setInterleaveCount(unsigned C) { StagedAttrs.InterleaveCount = C; }
260 
261   /// Set the unroll count for the next loop pushed.
262   void setUnrollCount(unsigned C) { StagedAttrs.UnrollCount = C; }
263 
264   /// \brief Set the unroll count for the next loop pushed.
265   void setUnrollAndJamCount(unsigned C) { StagedAttrs.UnrollAndJamCount = C; }
266 
267   /// Set the pipeline disabled state.
268   void setPipelineDisabled(bool S) { StagedAttrs.PipelineDisabled = S; }
269 
270   /// Set the pipeline initiation interval.
271   void setPipelineInitiationInterval(unsigned C) {
272     StagedAttrs.PipelineInitiationInterval = C;
273   }
274 
275 private:
276   /// Returns true if there is LoopInfo on the stack.
277   bool hasInfo() const { return !Active.empty(); }
278   /// Return the LoopInfo for the current loop. HasInfo should be called
279   /// first to ensure LoopInfo is present.
280   const LoopInfo &getInfo() const { return *Active.back(); }
281   /// The set of attributes that will be applied to the next pushed loop.
282   LoopAttributes StagedAttrs;
283   /// Stack of active loops.
284   llvm::SmallVector<std::unique_ptr<LoopInfo>, 4> Active;
285 };
286 
287 } // end namespace CodeGen
288 } // end namespace clang
289 
290 #endif
291