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/IR/Instruction.h"
35#include "llvm/IR/Operator.h"
36
37namespace llvm {
38
39template <typename T, typename... TArgs> class AnalysisManager;
40template <class T> class ArrayRef;
41class AssumptionCache;
42class BinaryOperator;
43class CallBase;
44class DataLayout;
45class DominatorTree;
46class Function;
47struct LoopStandardAnalysisResults;
48class MDNode;
49class OptimizationRemarkEmitter;
50class Pass;
51template <class T, unsigned n> class SmallSetVector;
52class TargetLibraryInfo;
53class Type;
54class Value;
55
56/// InstrInfoQuery provides an interface to query additional information for
57/// instructions like metadata or keywords like nsw, which provides conservative
58/// results if the users specified it is safe to use.
59struct InstrInfoQuery {
60  InstrInfoQuery(bool UMD) : UseInstrInfo(UMD) {}
61  InstrInfoQuery() : UseInstrInfo(true) {}
62  bool UseInstrInfo = true;
63
64  MDNode *getMetadata(const Instruction *I, unsigned KindID) const {
65    if (UseInstrInfo)
66      return I->getMetadata(KindID);
67    return nullptr;
68  }
69
70  template <class InstT> bool hasNoUnsignedWrap(const InstT *Op) const {
71    if (UseInstrInfo)
72      return Op->hasNoUnsignedWrap();
73    return false;
74  }
75
76  template <class InstT> bool hasNoSignedWrap(const InstT *Op) const {
77    if (UseInstrInfo)
78      return Op->hasNoSignedWrap();
79    return false;
80  }
81
82  bool isExact(const BinaryOperator *Op) const {
83    if (UseInstrInfo && isa<PossiblyExactOperator>(Op))
84      return cast<PossiblyExactOperator>(Op)->isExact();
85    return false;
86  }
87};
88
89struct SimplifyQuery {
90  const DataLayout &DL;
91  const TargetLibraryInfo *TLI = nullptr;
92  const DominatorTree *DT = nullptr;
93  AssumptionCache *AC = nullptr;
94  const Instruction *CxtI = nullptr;
95
96  // Wrapper to query additional information for instructions like metadata or
97  // keywords like nsw, which provides conservative results if those cannot
98  // be safely used.
99  const InstrInfoQuery IIQ;
100
101  SimplifyQuery(const DataLayout &DL, const Instruction *CXTI = nullptr)
102      : DL(DL), CxtI(CXTI) {}
103
104  SimplifyQuery(const DataLayout &DL, const TargetLibraryInfo *TLI,
105                const DominatorTree *DT = nullptr,
106                AssumptionCache *AC = nullptr,
107                const Instruction *CXTI = nullptr, bool UseInstrInfo = true)
108      : DL(DL), TLI(TLI), DT(DT), AC(AC), CxtI(CXTI), IIQ(UseInstrInfo) {}
109  SimplifyQuery getWithInstruction(Instruction *I) const {
110    SimplifyQuery Copy(*this);
111    Copy.CxtI = I;
112    return Copy;
113  }
114};
115
116// NOTE: the explicit multiple argument versions of these functions are
117// deprecated.
118// Please use the SimplifyQuery versions in new code.
119
120/// Given operand for an FNeg, fold the result or return null.
121Value *SimplifyFNegInst(Value *Op, FastMathFlags FMF,
122                        const SimplifyQuery &Q);
123
124/// Given operands for an Add, fold the result or return null.
125Value *SimplifyAddInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW,
126                       const SimplifyQuery &Q);
127
128/// Given operands for a Sub, fold the result or return null.
129Value *SimplifySubInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW,
130                       const SimplifyQuery &Q);
131
132/// Given operands for an FAdd, fold the result or return null.
133Value *SimplifyFAddInst(Value *LHS, Value *RHS, FastMathFlags FMF,
134                        const SimplifyQuery &Q);
135
136/// Given operands for an FSub, fold the result or return null.
137Value *SimplifyFSubInst(Value *LHS, Value *RHS, FastMathFlags FMF,
138                        const SimplifyQuery &Q);
139
140/// Given operands for an FMul, fold the result or return null.
141Value *SimplifyFMulInst(Value *LHS, Value *RHS, FastMathFlags FMF,
142                        const SimplifyQuery &Q);
143
144/// Given operands for the multiplication of a FMA, fold the result or return
145/// null. In contrast to SimplifyFMulInst, this function will not perform
146/// simplifications whose unrounded results differ when rounded to the argument
147/// type.
148Value *SimplifyFMAFMul(Value *LHS, Value *RHS, FastMathFlags FMF,
149                       const SimplifyQuery &Q);
150
151/// Given operands for a Mul, fold the result or return null.
152Value *SimplifyMulInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
153
154/// Given operands for an SDiv, fold the result or return null.
155Value *SimplifySDivInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
156
157/// Given operands for a UDiv, fold the result or return null.
158Value *SimplifyUDivInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
159
160/// Given operands for an FDiv, fold the result or return null.
161Value *SimplifyFDivInst(Value *LHS, Value *RHS, FastMathFlags FMF,
162                        const SimplifyQuery &Q);
163
164/// Given operands for an SRem, fold the result or return null.
165Value *SimplifySRemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
166
167/// Given operands for a URem, fold the result or return null.
168Value *SimplifyURemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
169
170/// Given operands for an FRem, fold the result or return null.
171Value *SimplifyFRemInst(Value *LHS, Value *RHS, FastMathFlags FMF,
172                        const SimplifyQuery &Q);
173
174/// Given operands for a Shl, fold the result or return null.
175Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
176                       const SimplifyQuery &Q);
177
178/// Given operands for a LShr, fold the result or return null.
179Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
180                        const SimplifyQuery &Q);
181
182/// Given operands for a AShr, fold the result or return nulll.
183Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
184                        const SimplifyQuery &Q);
185
186/// Given operands for an And, fold the result or return null.
187Value *SimplifyAndInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
188
189/// Given operands for an Or, fold the result or return null.
190Value *SimplifyOrInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
191
192/// Given operands for an Xor, fold the result or return null.
193Value *SimplifyXorInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
194
195/// Given operands for an ICmpInst, fold the result or return null.
196Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
197                        const SimplifyQuery &Q);
198
199/// Given operands for an FCmpInst, fold the result or return null.
200Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
201                        FastMathFlags FMF, const SimplifyQuery &Q);
202
203/// Given operands for a SelectInst, fold the result or return null.
204Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
205                          const SimplifyQuery &Q);
206
207/// Given operands for a GetElementPtrInst, fold the result or return null.
208Value *SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops,
209                       const SimplifyQuery &Q);
210
211/// Given operands for an InsertValueInst, fold the result or return null.
212Value *SimplifyInsertValueInst(Value *Agg, Value *Val, ArrayRef<unsigned> Idxs,
213                               const SimplifyQuery &Q);
214
215/// Given operands for an InsertElement, fold the result or return null.
216Value *SimplifyInsertElementInst(Value *Vec, Value *Elt, Value *Idx,
217                                 const SimplifyQuery &Q);
218
219/// Given operands for an ExtractValueInst, fold the result or return null.
220Value *SimplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs,
221                                const SimplifyQuery &Q);
222
223/// Given operands for an ExtractElementInst, fold the result or return null.
224Value *SimplifyExtractElementInst(Value *Vec, Value *Idx,
225                                  const SimplifyQuery &Q);
226
227/// Given operands for a CastInst, fold the result or return null.
228Value *SimplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty,
229                        const SimplifyQuery &Q);
230
231/// Given operands for a ShuffleVectorInst, fold the result or return null.
232/// See class ShuffleVectorInst for a description of the mask representation.
233Value *SimplifyShuffleVectorInst(Value *Op0, Value *Op1, ArrayRef<int> Mask,
234                                 Type *RetTy, const SimplifyQuery &Q);
235
236//=== Helper functions for higher up the class hierarchy.
237
238/// Given operands for a CmpInst, fold the result or return null.
239Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
240                       const SimplifyQuery &Q);
241
242/// Given operand for a UnaryOperator, fold the result or return null.
243Value *SimplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q);
244
245/// Given operand for a UnaryOperator, fold the result or return null.
246/// Try to use FastMathFlags when folding the result.
247Value *SimplifyUnOp(unsigned Opcode, Value *Op, FastMathFlags FMF,
248                    const SimplifyQuery &Q);
249
250/// Given operands for a BinaryOperator, fold the result or return null.
251Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
252                     const SimplifyQuery &Q);
253
254/// Given operands for a BinaryOperator, fold the result or return null.
255/// Try to use FastMathFlags when folding the result.
256Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
257                     FastMathFlags FMF, const SimplifyQuery &Q);
258
259/// Given a callsite, fold the result or return null.
260Value *SimplifyCall(CallBase *Call, const SimplifyQuery &Q);
261
262/// Given an operand for a Freeze, see if we can fold the result.
263/// If not, this returns null.
264Value *SimplifyFreezeInst(Value *Op, const SimplifyQuery &Q);
265
266/// See if we can compute a simplified version of this instruction. If not,
267/// return null.
268Value *SimplifyInstruction(Instruction *I, const SimplifyQuery &Q,
269                           OptimizationRemarkEmitter *ORE = nullptr);
270
271/// See if V simplifies when its operand Op is replaced with RepOp.
272/// AllowRefinement specifies whether the simplification can be a refinement,
273/// or whether it needs to be strictly identical.
274Value *SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
275                              const SimplifyQuery &Q, bool AllowRefinement);
276
277/// Replace all uses of 'I' with 'SimpleV' and simplify the uses recursively.
278///
279/// This first performs a normal RAUW of I with SimpleV. It then recursively
280/// attempts to simplify those users updated by the operation. The 'I'
281/// instruction must not be equal to the simplified value 'SimpleV'.
282/// If UnsimplifiedUsers is provided, instructions that could not be simplified
283/// are added to it.
284///
285/// The function returns true if any simplifications were performed.
286bool replaceAndRecursivelySimplify(
287    Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI = nullptr,
288    const DominatorTree *DT = nullptr, AssumptionCache *AC = nullptr,
289    SmallSetVector<Instruction *, 8> *UnsimplifiedUsers = nullptr);
290
291/// Recursively attempt to simplify an instruction.
292///
293/// This routine uses SimplifyInstruction to simplify 'I', and if successful
294/// replaces uses of 'I' with the simplified value. It then recurses on each
295/// of the users impacted. It returns true if any simplifications were
296/// performed.
297bool recursivelySimplifyInstruction(Instruction *I,
298                                    const TargetLibraryInfo *TLI = nullptr,
299                                    const DominatorTree *DT = nullptr,
300                                    AssumptionCache *AC = nullptr);
301
302// These helper functions return a SimplifyQuery structure that contains as
303// many of the optional analysis we use as are currently valid.  This is the
304// strongly preferred way of constructing SimplifyQuery in passes.
305const SimplifyQuery getBestSimplifyQuery(Pass &, Function &);
306template <class T, class... TArgs>
307const SimplifyQuery getBestSimplifyQuery(AnalysisManager<T, TArgs...> &,
308                                         Function &);
309const SimplifyQuery getBestSimplifyQuery(LoopStandardAnalysisResults &,
310                                         const DataLayout &);
311} // end namespace llvm
312
313#endif
314
315