1 //===-- llvm/Instruction.h - Instruction class definition -------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains the declaration of the Instruction class, which is the
11 // base class for all of the LLVM instructions.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_INSTRUCTION_H
16 #define LLVM_INSTRUCTION_H
18 #include "llvm/User.h"
19 #include "llvm/ADT/ilist_node.h"
25 template<typename ValueSubClass, typename ItemParentClass>
26 class SymbolTableListTraits;
28 class Instruction : public User, public ilist_node<Instruction> {
29 void operator=(const Instruction &); // Do not implement
30 Instruction(const Instruction &); // Do not implement
34 friend class SymbolTableListTraits<Instruction, BasicBlock>;
35 void setParent(BasicBlock *P);
37 Instruction(const Type *Ty, unsigned iType, Use *Ops, unsigned NumOps,
38 Instruction *InsertBefore = 0);
39 Instruction(const Type *Ty, unsigned iType, Use *Ops, unsigned NumOps,
40 BasicBlock *InsertAtEnd);
41 virtual Instruction *clone_impl() const = 0;
43 // Out of line virtual method, so the vtable, etc has a home.
46 /// clone() - Create a copy of 'this' instruction that is identical in all
47 /// ways except the following:
48 /// * The instruction has no parent
49 /// * The instruction has no name
51 Instruction *clone() const;
53 /// isIdenticalTo - Return true if the specified instruction is exactly
54 /// identical to the current one. This means that all operands match and any
55 /// extra information (e.g. load is volatile) agree.
56 bool isIdenticalTo(const Instruction *I) const;
58 /// isIdenticalToWhenDefined - This is like isIdenticalTo, except that it
59 /// ignores the SubclassOptionalData flags, which specify conditions
60 /// under which the instruction's result is undefined.
61 bool isIdenticalToWhenDefined(const Instruction *I) const;
63 /// This function determines if the specified instruction executes the same
64 /// operation as the current one. This means that the opcodes, type, operand
65 /// types and any other factors affecting the operation must be the same. This
66 /// is similar to isIdenticalTo except the operands themselves don't have to
68 /// @returns true if the specified instruction is the same operation as
70 /// @brief Determine if one instruction is the same operation as another.
71 bool isSameOperationAs(const Instruction *I) const;
73 /// isUsedOutsideOfBlock - Return true if there are any uses of this
74 /// instruction in blocks other than the specified block. Note that PHI nodes
75 /// are considered to evaluate their operands in the corresponding predecessor
77 bool isUsedOutsideOfBlock(const BasicBlock *BB) const;
80 /// use_back - Specialize the methods defined in Value, as we know that an
81 /// instruction can only be used by other instructions.
82 Instruction *use_back() { return cast<Instruction>(*use_begin());}
83 const Instruction *use_back() const { return cast<Instruction>(*use_begin());}
85 // Accessor methods...
87 inline const BasicBlock *getParent() const { return Parent; }
88 inline BasicBlock *getParent() { return Parent; }
90 /// removeFromParent - This method unlinks 'this' from the containing basic
91 /// block, but does not delete it.
93 void removeFromParent();
95 /// eraseFromParent - This method unlinks 'this' from the containing basic
96 /// block and deletes it.
98 void eraseFromParent();
100 /// insertBefore - Insert an unlinked instructions into a basic block
101 /// immediately before the specified instruction.
102 void insertBefore(Instruction *InsertPos);
104 /// insertAfter - Insert an unlinked instructions into a basic block
105 /// immediately after the specified instruction.
106 void insertAfter(Instruction *InsertPos);
108 /// moveBefore - Unlink this instruction from its current basic block and
109 /// insert it into the basic block that MovePos lives in, right before
111 void moveBefore(Instruction *MovePos);
113 // ---------------------------------------------------------------------------
114 /// Subclass classification... getOpcode() returns a member of
115 /// one of the enums that is coming soon (down below)...
117 unsigned getOpcode() const { return getValueID() - InstructionVal; }
118 const char *getOpcodeName() const { return getOpcodeName(getOpcode()); }
119 bool isTerminator() const { return isTerminator(getOpcode()); }
120 bool isBinaryOp() const { return isBinaryOp(getOpcode()); }
121 bool isShift() { return isShift(getOpcode()); }
122 bool isCast() const { return isCast(getOpcode()); }
126 static const char* getOpcodeName(unsigned OpCode);
128 static inline bool isTerminator(unsigned OpCode) {
129 return OpCode >= TermOpsBegin && OpCode < TermOpsEnd;
132 static inline bool isBinaryOp(unsigned Opcode) {
133 return Opcode >= BinaryOpsBegin && Opcode < BinaryOpsEnd;
136 /// @brief Determine if the Opcode is one of the shift instructions.
137 static inline bool isShift(unsigned Opcode) {
138 return Opcode >= Shl && Opcode <= AShr;
141 /// isLogicalShift - Return true if this is a logical shift left or a logical
143 inline bool isLogicalShift() const {
144 return getOpcode() == Shl || getOpcode() == LShr;
147 /// isArithmeticShift - Return true if this is an arithmetic shift right.
148 inline bool isArithmeticShift() const {
149 return getOpcode() == AShr;
152 /// @brief Determine if the OpCode is one of the CastInst instructions.
153 static inline bool isCast(unsigned OpCode) {
154 return OpCode >= CastOpsBegin && OpCode < CastOpsEnd;
157 /// isAssociative - Return true if the instruction is associative:
159 /// Associative operators satisfy: x op (y op z) === (x op y) op z
161 /// In LLVM, the Add, Mul, And, Or, and Xor operators are associative, when
162 /// not applied to floating point types.
164 bool isAssociative() const { return isAssociative(getOpcode(), getType()); }
165 static bool isAssociative(unsigned op, const Type *Ty);
167 /// isCommutative - Return true if the instruction is commutative:
169 /// Commutative operators satisfy: (x op y) === (y op x)
171 /// In LLVM, these are the associative operators, plus SetEQ and SetNE, when
172 /// applied to any type.
174 bool isCommutative() const { return isCommutative(getOpcode()); }
175 static bool isCommutative(unsigned op);
177 /// mayWriteToMemory - Return true if this instruction may modify memory.
179 bool mayWriteToMemory() const;
181 /// mayReadFromMemory - Return true if this instruction may read memory.
183 bool mayReadFromMemory() const;
185 /// mayThrow - Return true if this instruction may throw an exception.
187 bool mayThrow() const;
189 /// mayHaveSideEffects - Return true if the instruction may have side effects.
191 /// Note that this does not consider malloc and alloca to have side
192 /// effects because the newly allocated memory is completely invisible to
193 /// instructions which don't used the returned value. For cases where this
194 /// matters, isSafeToSpeculativelyExecute may be more appropriate.
195 bool mayHaveSideEffects() const {
196 return mayWriteToMemory() || mayThrow();
199 /// isSafeToSpeculativelyExecute - Return true if the instruction does not
200 /// have any effects besides calculating the result and does not have
201 /// undefined behavior.
203 /// This method never returns true for an instruction that returns true for
204 /// mayHaveSideEffects; however, this method also does some other checks in
205 /// addition. It checks for undefined behavior, like dividing by zero or
206 /// loading from an invalid pointer (but not for undefined results, like a
207 /// shift with a shift amount larger than the width of the result). It checks
208 /// for malloc and alloca because speculatively executing them might cause a
209 /// memory leak. It also returns false for instructions related to control
210 /// flow, specifically terminators and PHI nodes.
212 /// This method only looks at the instruction itself and its operands, so if
213 /// this method returns true, it is safe to move the instruction as long as
214 /// the correct dominance relationships for the operands and users hold.
215 /// However, this method can return true for instructions that read memory;
216 /// for such instructions, moving them may change the resulting value.
217 bool isSafeToSpeculativelyExecute() const;
219 /// Methods for support type inquiry through isa, cast, and dyn_cast:
220 static inline bool classof(const Instruction *) { return true; }
221 static inline bool classof(const Value *V) {
222 return V->getValueID() >= Value::InstructionVal;
225 //----------------------------------------------------------------------
226 // Exported enumerations...
228 enum TermOps { // These terminate basic blocks
229 #define FIRST_TERM_INST(N) TermOpsBegin = N,
230 #define HANDLE_TERM_INST(N, OPC, CLASS) OPC = N,
231 #define LAST_TERM_INST(N) TermOpsEnd = N+1
232 #include "llvm/Instruction.def"
236 #define FIRST_BINARY_INST(N) BinaryOpsBegin = N,
237 #define HANDLE_BINARY_INST(N, OPC, CLASS) OPC = N,
238 #define LAST_BINARY_INST(N) BinaryOpsEnd = N+1
239 #include "llvm/Instruction.def"
243 #define FIRST_MEMORY_INST(N) MemoryOpsBegin = N,
244 #define HANDLE_MEMORY_INST(N, OPC, CLASS) OPC = N,
245 #define LAST_MEMORY_INST(N) MemoryOpsEnd = N+1
246 #include "llvm/Instruction.def"
250 #define FIRST_CAST_INST(N) CastOpsBegin = N,
251 #define HANDLE_CAST_INST(N, OPC, CLASS) OPC = N,
252 #define LAST_CAST_INST(N) CastOpsEnd = N+1
253 #include "llvm/Instruction.def"
257 #define FIRST_OTHER_INST(N) OtherOpsBegin = N,
258 #define HANDLE_OTHER_INST(N, OPC, CLASS) OPC = N,
259 #define LAST_OTHER_INST(N) OtherOpsEnd = N+1
260 #include "llvm/Instruction.def"
264 // Instruction* is only 4-byte aligned.
266 class PointerLikeTypeTraits<Instruction*> {
267 typedef Instruction* PT;
269 static inline void *getAsVoidPointer(PT P) { return P; }
270 static inline PT getFromVoidPointer(void *P) {
271 return static_cast<PT>(P);
273 enum { NumLowBitsAvailable = 2 };
276 } // End llvm namespace