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InstructionSimplify.h
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1 //===-- InstructionSimplify.h - Fold instrs into simpler forms --*- 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 file declares routines for folding instructions into simpler forms
11 // that do not require creating new instructions. This does constant folding
12 // ("add i32 1, 1" -> "2") but can also handle non-constant operands, either
13 // returning a constant ("and i32 %x, 0" -> "0") or an already existing value
14 // ("and i32 %x, %x" -> "%x"). If the simplification is also an instruction
15 // then it dominates the original instruction.
16 //
17 // These routines implicitly resolve undef uses. The easiest way to be safe when
18 // using these routines to obtain simplified values for existing instructions is
19 // to always replace all uses of the instructions with the resulting simplified
20 // values. This will prevent other code from seeing the same undef uses and
21 // resolving them to different values.
22 //
23 // These routines are designed to tolerate moderately incomplete IR, such as
24 // instructions that are not connected to basic blocks yet. However, they do
25 // require that all the IR that they encounter be valid. In particular, they
26 // require that all non-constant values be defined in the same function, and the
27 // same call context of that function (and not split between caller and callee
28 // contexts of a directly recursive call, for example).
29 //
30 //===----------------------------------------------------------------------===//
31 
32 #ifndef LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H
33 #define LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H
34 
35 #include "llvm/IR/Instruction.h"
36 #include "llvm/IR/Operator.h"
37 #include "llvm/IR/User.h"
38 
39 namespace llvm {
40 class Function;
41 template <typename T, typename... TArgs> class AnalysisManager;
42 template <class T> class ArrayRef;
43 class AssumptionCache;
44 class DominatorTree;
45 class ImmutableCallSite;
46 class DataLayout;
47 class FastMathFlags;
50 class Pass;
51 class TargetLibraryInfo;
52 class Type;
53 class Value;
54 class MDNode;
55 class BinaryOperator;
56 
57 /// InstrInfoQuery provides an interface to query additional information for
58 /// instructions like metadata or keywords like nsw, which provides conservative
59 /// results if the users specified it is safe to use.
61  InstrInfoQuery(bool UMD) : UseInstrInfo(UMD) {}
63  bool UseInstrInfo = true;
64 
65  MDNode *getMetadata(const Instruction *I, unsigned KindID) const {
66  if (UseInstrInfo)
67  return I->getMetadata(KindID);
68  return nullptr;
69  }
70 
71  template <class InstT> bool hasNoUnsignedWrap(const InstT *Op) const {
72  if (UseInstrInfo)
73  return Op->hasNoUnsignedWrap();
74  return false;
75  }
76 
77  template <class InstT> bool hasNoSignedWrap(const InstT *Op) const {
78  if (UseInstrInfo)
79  return Op->hasNoSignedWrap();
80  return false;
81  }
82 
83  bool isExact(const BinaryOperator *Op) const {
84  if (UseInstrInfo && isa<PossiblyExactOperator>(Op))
85  return cast<PossiblyExactOperator>(Op)->isExact();
86  return false;
87  }
88 };
89 
90 struct SimplifyQuery {
91  const DataLayout &DL;
92  const TargetLibraryInfo *TLI = nullptr;
93  const DominatorTree *DT = nullptr;
94  AssumptionCache *AC = nullptr;
95  const Instruction *CxtI = nullptr;
96 
97  // Wrapper to query additional information for instructions like metadata or
98  // keywords like nsw, which provides conservative results if those cannot
99  // be safely used.
101 
102  SimplifyQuery(const DataLayout &DL, const Instruction *CXTI = nullptr)
103  : DL(DL), CxtI(CXTI) {}
104 
106  const DominatorTree *DT = nullptr,
107  AssumptionCache *AC = nullptr,
108  const Instruction *CXTI = nullptr, bool UseInstrInfo = true)
109  : DL(DL), TLI(TLI), DT(DT), AC(AC), CxtI(CXTI), IIQ(UseInstrInfo) {}
111  SimplifyQuery Copy(*this);
112  Copy.CxtI = I;
113  return Copy;
114  }
115 };
116 
117 // NOTE: the explicit multiple argument versions of these functions are
118 // deprecated.
119 // Please use the SimplifyQuery versions in new code.
120 
121 /// Given operands for an Add, fold the result or return null.
122 Value *SimplifyAddInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW,
123  const SimplifyQuery &Q);
124 
125 /// Given operands for a Sub, fold the result or return null.
126 Value *SimplifySubInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW,
127  const SimplifyQuery &Q);
128 
129 /// Given operands for an FAdd, fold the result or return null.
131  const SimplifyQuery &Q);
132 
133 /// Given operands for an FSub, fold the result or return null.
135  const SimplifyQuery &Q);
136 
137 /// Given operands for an FMul, fold the result or return null.
139  const SimplifyQuery &Q);
140 
141 /// Given operands for a Mul, fold the result or return null.
142 Value *SimplifyMulInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
143 
144 /// Given operands for an SDiv, fold the result or return null.
145 Value *SimplifySDivInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
146 
147 /// Given operands for a UDiv, fold the result or return null.
148 Value *SimplifyUDivInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
149 
150 /// Given operands for an FDiv, fold the result or return null.
152  const SimplifyQuery &Q);
153 
154 /// Given operands for an SRem, fold the result or return null.
155 Value *SimplifySRemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
156 
157 /// Given operands for a URem, fold the result or return null.
158 Value *SimplifyURemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
159 
160 /// Given operands for an FRem, fold the result or return null.
162  const SimplifyQuery &Q);
163 
164 /// Given operands for a Shl, fold the result or return null.
165 Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
166  const SimplifyQuery &Q);
167 
168 /// Given operands for a LShr, fold the result or return null.
169 Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
170  const SimplifyQuery &Q);
171 
172 /// Given operands for a AShr, fold the result or return nulll.
173 Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
174  const SimplifyQuery &Q);
175 
176 /// Given operands for an And, fold the result or return null.
177 Value *SimplifyAndInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
178 
179 /// Given operands for an Or, fold the result or return null.
180 Value *SimplifyOrInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
181 
182 /// Given operands for an Xor, fold the result or return null.
183 Value *SimplifyXorInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
184 
185 /// Given operands for an ICmpInst, fold the result or return null.
186 Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
187  const SimplifyQuery &Q);
188 
189 /// Given operands for an FCmpInst, fold the result or return null.
190 Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
191  FastMathFlags FMF, const SimplifyQuery &Q);
192 
193 /// Given operands for a SelectInst, fold the result or return null.
194 Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
195  const SimplifyQuery &Q);
196 
197 /// Given operands for a GetElementPtrInst, fold the result or return null.
199  const SimplifyQuery &Q);
200 
201 /// Given operands for an InsertValueInst, fold the result or return null.
203  const SimplifyQuery &Q);
204 
205 /// Given operands for an InsertElement, fold the result or return null.
207  const SimplifyQuery &Q);
208 
209 /// Given operands for an ExtractValueInst, fold the result or return null.
211  const SimplifyQuery &Q);
212 
213 /// Given operands for an ExtractElementInst, fold the result or return null.
215  const SimplifyQuery &Q);
216 
217 /// Given operands for a CastInst, fold the result or return null.
218 Value *SimplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty,
219  const SimplifyQuery &Q);
220 
221 /// Given operands for a ShuffleVectorInst, fold the result or return null.
223  Type *RetTy, const SimplifyQuery &Q);
224 
225 //=== Helper functions for higher up the class hierarchy.
226 
227 /// Given operands for a CmpInst, fold the result or return null.
228 Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
229  const SimplifyQuery &Q);
230 
231 /// Given operands for a BinaryOperator, fold the result or return null.
232 Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
233  const SimplifyQuery &Q);
234 
235 /// Given operands for an FP BinaryOperator, fold the result or return null.
236 /// In contrast to SimplifyBinOp, try to use FastMathFlag when folding the
237 /// result. In case we don't need FastMathFlags, simply fall to SimplifyBinOp.
238 Value *SimplifyFPBinOp(unsigned Opcode, Value *LHS, Value *RHS,
239  FastMathFlags FMF, const SimplifyQuery &Q);
240 
241 /// Given a callsite, fold the result or return null.
243 
244 /// Given a function and iterators over arguments, fold the result or return
245 /// null.
247  User::op_iterator ArgEnd, const SimplifyQuery &Q);
248 
249 /// Given a function and set of arguments, fold the result or return null.
251  const SimplifyQuery &Q);
252 
253 /// See if we can compute a simplified version of this instruction. If not,
254 /// return null.
256  OptimizationRemarkEmitter *ORE = nullptr);
257 
258 /// Replace all uses of 'I' with 'SimpleV' and simplify the uses recursively.
259 ///
260 /// This first performs a normal RAUW of I with SimpleV. It then recursively
261 /// attempts to simplify those users updated by the operation. The 'I'
262 /// instruction must not be equal to the simplified value 'SimpleV'.
263 ///
264 /// The function returns true if any simplifications were performed.
266  const TargetLibraryInfo *TLI = nullptr,
267  const DominatorTree *DT = nullptr,
268  AssumptionCache *AC = nullptr);
269 
270 /// Recursively attempt to simplify an instruction.
271 ///
272 /// This routine uses SimplifyInstruction to simplify 'I', and if successful
273 /// replaces uses of 'I' with the simplified value. It then recurses on each
274 /// of the users impacted. It returns true if any simplifications were
275 /// performed.
277  const TargetLibraryInfo *TLI = nullptr,
278  const DominatorTree *DT = nullptr,
279  AssumptionCache *AC = nullptr);
280 
281 // These helper functions return a SimplifyQuery structure that contains as
282 // many of the optional analysis we use as are currently valid. This is the
283 // strongly preferred way of constructing SimplifyQuery in passes.
285 template <class T, class... TArgs>
287  Function &);
289  const DataLayout &);
290 } // end namespace llvm
291 
292 #endif
293 
Pass interface - Implemented by all &#39;passes&#39;.
Definition: Pass.h:81
Value * SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, const SimplifyQuery &Q)
Given operands for an ICmpInst, fold the result or return null.
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:111
const InstrInfoQuery IIQ
Value * SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, FastMathFlags FMF, const SimplifyQuery &Q)
Given operands for an FCmpInst, fold the result or return null.
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
SimplifyQuery getWithInstruction(Instruction *I) const
const Instruction * CxtI
A cache of @llvm.assume calls within a function.
Value * SimplifySDivInst(Value *LHS, Value *RHS, const SimplifyQuery &Q)
Given operands for an SDiv, fold the result or return null.
Value * SimplifyUDivInst(Value *LHS, Value *RHS, const SimplifyQuery &Q)
Given operands for a UDiv, fold the result or return null.
Metadata node.
Definition: Metadata.h:864
The adaptor from a function pass to a loop pass computes these analyses and makes them available to t...
Value * SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, const SimplifyQuery &Q)
Given operands for a Shl, fold the result or return null.
block Block Frequency true
const SimplifyQuery getBestSimplifyQuery(Pass &, Function &)
Value * SimplifyOrInst(Value *LHS, Value *RHS, const SimplifyQuery &Q)
Given operands for an Or, fold the result or return null.
Value * SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, const SimplifyQuery &Q)
Given operands for a LShr, fold the result or return null.
Value * SimplifyFPBinOp(unsigned Opcode, Value *LHS, Value *RHS, FastMathFlags FMF, const SimplifyQuery &Q)
Given operands for an FP BinaryOperator, fold the result or return null.
Value * SimplifyExtractValueInst(Value *Agg, ArrayRef< unsigned > Idxs, const SimplifyQuery &Q)
Given operands for an ExtractValueInst, fold the result or return null.
SimplifyQuery(const DataLayout &DL, const Instruction *CXTI=nullptr)
Value * SimplifyGEPInst(Type *SrcTy, ArrayRef< Value *> Ops, const SimplifyQuery &Q)
Given operands for a GetElementPtrInst, fold the result or return null.
A Use represents the edge between a Value definition and its users.
Definition: Use.h:56
bool hasNoUnsignedWrap(const InstT *Op) const
Value * SimplifyFAddInst(Value *LHS, Value *RHS, FastMathFlags FMF, const SimplifyQuery &Q)
Given operands for an FAdd, fold the result or return null.
Value * SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, const SimplifyQuery &Q)
Given operands for a CmpInst, fold the result or return null.
#define T
Value * SimplifyMulInst(Value *LHS, Value *RHS, const SimplifyQuery &Q)
Given operands for a Mul, fold the result or return null.
MDNode * getMetadata(unsigned KindID) const
Get the metadata of given kind attached to this Instruction.
Definition: Instruction.h:217
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory)...
Definition: APInt.h:33
bool isExact(const BinaryOperator *Op) const
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:145
SimplifyQuery(const DataLayout &DL, const TargetLibraryInfo *TLI, const DominatorTree *DT=nullptr, AssumptionCache *AC=nullptr, const Instruction *CXTI=nullptr, bool UseInstrInfo=true)
Value * SimplifyInsertElementInst(Value *Vec, Value *Elt, Value *Idx, const SimplifyQuery &Q)
Given operands for an InsertElement, fold the result or return null.
MDNode * getMetadata(const Instruction *I, unsigned KindID) const
Value * SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, const SimplifyQuery &Q)
Given operands for a SelectInst, fold the result or return null.
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
Value * SimplifyURemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q)
Given operands for a URem, fold the result or return null.
This is an important base class in LLVM.
Definition: Constant.h:42
InstrInfoQuery provides an interface to query additional information for instructions like metadata o...
Value * SimplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty, const SimplifyQuery &Q)
Given operands for a CastInst, fold the result or return null.
Value * SimplifyAddInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW, const SimplifyQuery &Q)
Given operands for an Add, fold the result or return null.
Value * SimplifyFDivInst(Value *LHS, Value *RHS, FastMathFlags FMF, const SimplifyQuery &Q)
Given operands for an FDiv, fold the result or return null.
Value * SimplifyFRemInst(Value *LHS, Value *RHS, FastMathFlags FMF, const SimplifyQuery &Q)
Given operands for an FRem, fold the result or return null.
Value * SimplifyShuffleVectorInst(Value *Op0, Value *Op1, Constant *Mask, Type *RetTy, const SimplifyQuery &Q)
Given operands for a ShuffleVectorInst, fold the result or return null.
bool recursivelySimplifyInstruction(Instruction *I, const TargetLibraryInfo *TLI=nullptr, const DominatorTree *DT=nullptr, AssumptionCache *AC=nullptr)
Recursively attempt to simplify an instruction.
Provides information about what library functions are available for the current target.
Predicate
Predicate - These are "(BI << 5) | BO" for various predicates.
Definition: PPCPredicates.h:27
Value * SimplifyCall(ImmutableCallSite CS, const SimplifyQuery &Q)
Given a callsite, fold the result or return null.
Value * SimplifyFSubInst(Value *LHS, Value *RHS, FastMathFlags FMF, const SimplifyQuery &Q)
Given operands for an FSub, fold the result or return null.
Value * SimplifyFMulInst(Value *LHS, Value *RHS, FastMathFlags FMF, const SimplifyQuery &Q)
Given operands for an FMul, fold the result or return null.
Value * SimplifyAndInst(Value *LHS, Value *RHS, const SimplifyQuery &Q)
Given operands for an And, fold the result or return null.
Establish a view to a call site for examination.
Definition: CallSite.h:714
Value * SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, const SimplifyQuery &Q)
Given operands for a AShr, fold the result or return nulll.
#define I(x, y, z)
Definition: MD5.cpp:58
Value * SimplifyXorInst(Value *LHS, Value *RHS, const SimplifyQuery &Q)
Given operands for an Xor, fold the result or return null.
Value * SimplifySRemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q)
Given operands for an SRem, fold the result or return null.
Value * SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, const SimplifyQuery &Q)
Given operands for a BinaryOperator, fold the result or return null.
LLVM Value Representation.
Definition: Value.h:73
Value * SimplifyExtractElementInst(Value *Vec, Value *Idx, const SimplifyQuery &Q)
Given operands for an ExtractElementInst, fold the result or return null.
std::underlying_type< E >::type Mask()
Get a bitmask with 1s in all places up to the high-order bit of E&#39;s largest value.
Definition: BitmaskEnum.h:81
const DataLayout & DL
Value * SimplifySubInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW, const SimplifyQuery &Q)
Given operands for a Sub, fold the result or return null.
Value * SimplifyInsertValueInst(Value *Agg, Value *Val, ArrayRef< unsigned > Idxs, const SimplifyQuery &Q)
Given operands for an InsertValueInst, fold the result or return null.
Convenience struct for specifying and reasoning about fast-math flags.
Definition: Operator.h:160
A container for analyses that lazily runs them and caches their results.
bool replaceAndRecursivelySimplify(Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI=nullptr, const DominatorTree *DT=nullptr, AssumptionCache *AC=nullptr)
Replace all uses of &#39;I&#39; with &#39;SimpleV&#39; and simplify the uses recursively.
bool hasNoSignedWrap(const InstT *Op) const
Value * SimplifyInstruction(Instruction *I, const SimplifyQuery &Q, OptimizationRemarkEmitter *ORE=nullptr)
See if we can compute a simplified version of this instruction.
The optimization diagnostic interface.
constexpr char Args[]
Key for Kernel::Metadata::mArgs.