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InstructionSimplify.h
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1 //===-- InstructionSimplify.h - Fold instrs into simpler forms --*- 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 file declares routines for folding instructions into simpler forms
10 // that do not require creating new instructions. This does constant folding
11 // ("add i32 1, 1" -> "2") but can also handle non-constant operands, either
12 // returning a constant ("and i32 %x, 0" -> "0") or an already existing value
13 // ("and i32 %x, %x" -> "%x"). If the simplification is also an instruction
14 // then it dominates the original instruction.
15 //
16 // These routines implicitly resolve undef uses. The easiest way to be safe when
17 // using these routines to obtain simplified values for existing instructions is
18 // to always replace all uses of the instructions with the resulting simplified
19 // values. This will prevent other code from seeing the same undef uses and
20 // resolving them to different values.
21 //
22 // These routines are designed to tolerate moderately incomplete IR, such as
23 // instructions that are not connected to basic blocks yet. However, they do
24 // require that all the IR that they encounter be valid. In particular, they
25 // require that all non-constant values be defined in the same function, and the
26 // same call context of that function (and not split between caller and callee
27 // contexts of a directly recursive call, for example).
28 //
29 //===----------------------------------------------------------------------===//
30 
31 #ifndef LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H
32 #define LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H
33 
34 #include "llvm/ADT/SetVector.h"
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 CallBase;
45 class DominatorTree;
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 operand for an FNeg, fold the result or return null.
123  const SimplifyQuery &Q);
124 
125 /// Given operands for an Add, fold the result or return null.
126 Value *SimplifyAddInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW,
127  const SimplifyQuery &Q);
128 
129 /// Given operands for a Sub, fold the result or return null.
130 Value *SimplifySubInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW,
131  const SimplifyQuery &Q);
132 
133 /// Given operands for an FAdd, fold the result or return null.
135  const SimplifyQuery &Q);
136 
137 /// Given operands for an FSub, fold the result or return null.
139  const SimplifyQuery &Q);
140 
141 /// Given operands for an FMul, fold the result or return null.
143  const SimplifyQuery &Q);
144 
145 /// Given operands for a Mul, fold the result or return null.
146 Value *SimplifyMulInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
147 
148 /// Given operands for an SDiv, fold the result or return null.
149 Value *SimplifySDivInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
150 
151 /// Given operands for a UDiv, fold the result or return null.
152 Value *SimplifyUDivInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
153 
154 /// Given operands for an FDiv, fold the result or return null.
156  const SimplifyQuery &Q);
157 
158 /// Given operands for an SRem, fold the result or return null.
159 Value *SimplifySRemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
160 
161 /// Given operands for a URem, fold the result or return null.
162 Value *SimplifyURemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
163 
164 /// Given operands for an FRem, fold the result or return null.
166  const SimplifyQuery &Q);
167 
168 /// Given operands for a Shl, fold the result or return null.
169 Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
170  const SimplifyQuery &Q);
171 
172 /// Given operands for a LShr, fold the result or return null.
173 Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
174  const SimplifyQuery &Q);
175 
176 /// Given operands for a AShr, fold the result or return nulll.
177 Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
178  const SimplifyQuery &Q);
179 
180 /// Given operands for an And, fold the result or return null.
181 Value *SimplifyAndInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
182 
183 /// Given operands for an Or, fold the result or return null.
184 Value *SimplifyOrInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
185 
186 /// Given operands for an Xor, fold the result or return null.
187 Value *SimplifyXorInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
188 
189 /// Given operands for an ICmpInst, fold the result or return null.
190 Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
191  const SimplifyQuery &Q);
192 
193 /// Given operands for an FCmpInst, fold the result or return null.
194 Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
195  FastMathFlags FMF, const SimplifyQuery &Q);
196 
197 /// Given operands for a SelectInst, fold the result or return null.
198 Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
199  const SimplifyQuery &Q);
200 
201 /// Given operands for a GetElementPtrInst, fold the result or return null.
203  const SimplifyQuery &Q);
204 
205 /// Given operands for an InsertValueInst, fold the result or return null.
207  const SimplifyQuery &Q);
208 
209 /// Given operands for an InsertElement, fold the result or return null.
211  const SimplifyQuery &Q);
212 
213 /// Given operands for an ExtractValueInst, fold the result or return null.
215  const SimplifyQuery &Q);
216 
217 /// Given operands for an ExtractElementInst, fold the result or return null.
219  const SimplifyQuery &Q);
220 
221 /// Given operands for a CastInst, fold the result or return null.
222 Value *SimplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty,
223  const SimplifyQuery &Q);
224 
225 /// Given operands for a ShuffleVectorInst, fold the result or return null.
227  Type *RetTy, const SimplifyQuery &Q);
228 
229 //=== Helper functions for higher up the class hierarchy.
230 
231 /// Given operands for a CmpInst, fold the result or return null.
232 Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
233  const SimplifyQuery &Q);
234 
235 /// Given operand for a UnaryOperator, fold the result or return null.
236 Value *SimplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q);
237 
238 /// Given operand for a UnaryOperator, fold the result or return null.
239 /// Try to use FastMathFlags when folding the result.
240 Value *SimplifyUnOp(unsigned Opcode, Value *Op, FastMathFlags FMF,
241  const SimplifyQuery &Q);
242 
243 /// Given operands for a BinaryOperator, fold the result or return null.
244 Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
245  const SimplifyQuery &Q);
246 
247 /// Given operands for a BinaryOperator, fold the result or return null.
248 /// Try to use FastMathFlags when folding the result.
249 Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
250  FastMathFlags FMF, const SimplifyQuery &Q);
251 
252 /// Given a callsite, fold the result or return null.
253 Value *SimplifyCall(CallBase *Call, const SimplifyQuery &Q);
254 
255 /// See if we can compute a simplified version of this instruction. If not,
256 /// return null.
258  OptimizationRemarkEmitter *ORE = nullptr);
259 
260 /// Replace all uses of 'I' with 'SimpleV' and simplify the uses recursively.
261 ///
262 /// This first performs a normal RAUW of I with SimpleV. It then recursively
263 /// attempts to simplify those users updated by the operation. The 'I'
264 /// instruction must not be equal to the simplified value 'SimpleV'.
265 /// If UnsimplifiedUsers is provided, instructions that could not be simplified
266 /// are added to it.
267 ///
268 /// The function returns true if any simplifications were performed.
270  Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI = nullptr,
271  const DominatorTree *DT = nullptr, AssumptionCache *AC = nullptr,
272  SmallSetVector<Instruction *, 8> *UnsimplifiedUsers = nullptr);
273 
274 /// Recursively attempt to simplify an instruction.
275 ///
276 /// This routine uses SimplifyInstruction to simplify 'I', and if successful
277 /// replaces uses of 'I' with the simplified value. It then recurses on each
278 /// of the users impacted. It returns true if any simplifications were
279 /// performed.
281  const TargetLibraryInfo *TLI = nullptr,
282  const DominatorTree *DT = nullptr,
283  AssumptionCache *AC = nullptr);
284 
285 // These helper functions return a SimplifyQuery structure that contains as
286 // many of the optional analysis we use as are currently valid. This is the
287 // strongly preferred way of constructing SimplifyQuery in passes.
289 template <class T, class... TArgs>
291  Function &);
293  const DataLayout &);
294 } // end namespace llvm
295 
296 #endif
297 
Pass interface - Implemented by all &#39;passes&#39;.
Definition: Pass.h:80
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.
This class represents lattice values for constants.
Definition: AllocatorList.h:23
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:863
The adaptor from a function pass to a loop pass computes these analyses and makes them available to t...
Base class for all callable instructions (InvokeInst and CallInst) Holds everything related to callin...
Definition: InstrTypes.h:1100
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 * 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)
bool replaceAndRecursivelySimplify(Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI=nullptr, const DominatorTree *DT=nullptr, AssumptionCache *AC=nullptr, SmallSetVector< Instruction *, 8 > *UnsimplifiedUsers=nullptr)
Replace all uses of &#39;I&#39; with &#39;SimpleV&#39; and simplify the uses recursively.
Value * SimplifyGEPInst(Type *SrcTy, ArrayRef< Value *> Ops, const SimplifyQuery &Q)
Given operands for a GetElementPtrInst, fold the result or return null.
bool hasNoUnsignedWrap(const InstT *Op) const
Value * SimplifyFNegInst(Value *Op, FastMathFlags FMF, const SimplifyQuery &Q)
Given operand for an FNeg, fold the result or return null.
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.
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:244
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory)...
Definition: APInt.h:32
bool isExact(const BinaryOperator *Op) const
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:144
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:45
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:41
InstrInfoQuery provides an interface to query additional information for instructions like metadata o...
Value * SimplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q)
Given operand for a UnaryOperator, fold the result or return null.
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 * SimplifyCall(CallBase *Call, const SimplifyQuery &Q)
Given a callsite, 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.
A SetVector that performs no allocations if smaller than a certain size.
Definition: SetVector.h:297
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:26
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.
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:80
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:159
A container for analyses that lazily runs them and caches their results.
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.