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);
42 // Out of line virtual method, so the vtable, etc has a home.
45 /// clone() - Create a copy of 'this' instruction that is identical in all
46 /// ways except the following:
47 /// * The instruction has no parent
48 /// * The instruction has no name
50 virtual Instruction *clone(LLVMContext &Context) const = 0;
52 /// isIdenticalTo - Return true if the specified instruction is exactly
53 /// identical to the current one. This means that all operands match and any
54 /// extra information (e.g. load is volatile) agree.
55 bool isIdenticalTo(const Instruction *I) const;
57 /// This function determines if the specified instruction executes the same
58 /// operation as the current one. This means that the opcodes, type, operand
59 /// types and any other factors affecting the operation must be the same. This
60 /// is similar to isIdenticalTo except the operands themselves don't have to
62 /// @returns true if the specified instruction is the same operation as
64 /// @brief Determine if one instruction is the same operation as another.
65 bool isSameOperationAs(const Instruction *I) const;
67 /// isUsedOutsideOfBlock - Return true if there are any uses of this
68 /// instruction in blocks other than the specified block. Note that PHI nodes
69 /// are considered to evaluate their operands in the corresponding predecessor
71 bool isUsedOutsideOfBlock(const BasicBlock *BB) const;
74 /// use_back - Specialize the methods defined in Value, as we know that an
75 /// instruction can only be used by other instructions.
76 Instruction *use_back() { return cast<Instruction>(*use_begin());}
77 const Instruction *use_back() const { return cast<Instruction>(*use_begin());}
79 // Accessor methods...
81 inline const BasicBlock *getParent() const { return Parent; }
82 inline BasicBlock *getParent() { return Parent; }
84 /// removeFromParent - This method unlinks 'this' from the containing basic
85 /// block, but does not delete it.
87 void removeFromParent();
89 /// eraseFromParent - This method unlinks 'this' from the containing basic
90 /// block and deletes it.
92 void eraseFromParent();
94 /// insertBefore - Insert an unlinked instructions into a basic block
95 /// immediately before the specified instruction.
96 void insertBefore(Instruction *InsertPos);
98 /// insertAfter - Insert an unlinked instructions into a basic block
99 /// immediately after the specified instruction.
100 void insertAfter(Instruction *InsertPos);
102 /// moveBefore - Unlink this instruction from its current basic block and
103 /// insert it into the basic block that MovePos lives in, right before
105 void moveBefore(Instruction *MovePos);
107 // ---------------------------------------------------------------------------
108 /// Subclass classification... getOpcode() returns a member of
109 /// one of the enums that is coming soon (down below)...
111 unsigned getOpcode() const { return getValueID() - InstructionVal; }
112 const char *getOpcodeName() const { return getOpcodeName(getOpcode()); }
113 bool isTerminator() const { return isTerminator(getOpcode()); }
114 bool isBinaryOp() const { return isBinaryOp(getOpcode()); }
115 bool isShift() { return isShift(getOpcode()); }
116 bool isCast() const { return isCast(getOpcode()); }
120 static const char* getOpcodeName(unsigned OpCode);
122 static inline bool isTerminator(unsigned OpCode) {
123 return OpCode >= TermOpsBegin && OpCode < TermOpsEnd;
126 static inline bool isBinaryOp(unsigned Opcode) {
127 return Opcode >= BinaryOpsBegin && Opcode < BinaryOpsEnd;
130 /// @brief Determine if the Opcode is one of the shift instructions.
131 static inline bool isShift(unsigned Opcode) {
132 return Opcode >= Shl && Opcode <= AShr;
135 /// isLogicalShift - Return true if this is a logical shift left or a logical
137 inline bool isLogicalShift() const {
138 return getOpcode() == Shl || getOpcode() == LShr;
141 /// isArithmeticShift - Return true if this is an arithmetic shift right.
142 inline bool isArithmeticShift() const {
143 return getOpcode() == AShr;
146 /// @brief Determine if the OpCode is one of the CastInst instructions.
147 static inline bool isCast(unsigned OpCode) {
148 return OpCode >= CastOpsBegin && OpCode < CastOpsEnd;
151 /// isAssociative - Return true if the instruction is associative:
153 /// Associative operators satisfy: x op (y op z) === (x op y) op z
155 /// In LLVM, the Add, Mul, And, Or, and Xor operators are associative, when
156 /// not applied to floating point types.
158 bool isAssociative() const { return isAssociative(getOpcode(), getType()); }
159 static bool isAssociative(unsigned op, const Type *Ty);
161 /// isCommutative - Return true if the instruction is commutative:
163 /// Commutative operators satisfy: (x op y) === (y op x)
165 /// In LLVM, these are the associative operators, plus SetEQ and SetNE, when
166 /// applied to any type.
168 bool isCommutative() const { return isCommutative(getOpcode()); }
169 static bool isCommutative(unsigned op);
171 /// mayWriteToMemory - Return true if this instruction may modify memory.
173 bool mayWriteToMemory() const;
175 /// mayReadFromMemory - Return true if this instruction may read memory.
177 bool mayReadFromMemory() const;
179 /// mayThrow - Return true if this instruction may throw an exception.
181 bool mayThrow() const;
183 /// mayHaveSideEffects - Return true if the instruction may have side effects.
185 /// Note that this does not consider malloc and alloca to have side
186 /// effects because the newly allocated memory is completely invisible to
187 /// instructions which don't used the returned value. For cases where this
188 /// matters, isSafeToSpeculativelyExecute may be more appropriate.
189 bool mayHaveSideEffects() const {
190 return mayWriteToMemory() || mayThrow();
193 /// isSafeToSpeculativelyExecute - Return true if the instruction does not
194 /// have any effects besides calculating the result and does not have
195 /// undefined behavior.
197 /// This method never returns true for an instruction that returns true for
198 /// mayHaveSideEffects; however, this method also does some other checks in
199 /// addition. It checks for undefined behavior, like dividing by zero or
200 /// loading from an invalid pointer (but not for undefined results, like a
201 /// shift with a shift amount larger than the width of the result). It checks
202 /// for malloc and alloca because speculatively executing them might cause a
203 /// memory leak. It also returns false for instructions related to control
204 /// flow, specifically terminators and PHI nodes.
206 /// This method only looks at the instruction itself and its operands, so if
207 /// this method returns true, it is safe to move the instruction as long as
208 /// the correct dominance relationships for the operands and users hold.
209 /// However, this method can return true for instructions that read memory;
210 /// for such instructions, moving them may change the resulting value.
211 bool isSafeToSpeculativelyExecute() const;
213 /// Methods for support type inquiry through isa, cast, and dyn_cast:
214 static inline bool classof(const Instruction *) { return true; }
215 static inline bool classof(const Value *V) {
216 return V->getValueID() >= Value::InstructionVal;
219 //----------------------------------------------------------------------
220 // Exported enumerations...
222 enum TermOps { // These terminate basic blocks
223 #define FIRST_TERM_INST(N) TermOpsBegin = N,
224 #define HANDLE_TERM_INST(N, OPC, CLASS) OPC = N,
225 #define LAST_TERM_INST(N) TermOpsEnd = N+1
226 #include "llvm/Instruction.def"
230 #define FIRST_BINARY_INST(N) BinaryOpsBegin = N,
231 #define HANDLE_BINARY_INST(N, OPC, CLASS) OPC = N,
232 #define LAST_BINARY_INST(N) BinaryOpsEnd = N+1
233 #include "llvm/Instruction.def"
237 #define FIRST_MEMORY_INST(N) MemoryOpsBegin = N,
238 #define HANDLE_MEMORY_INST(N, OPC, CLASS) OPC = N,
239 #define LAST_MEMORY_INST(N) MemoryOpsEnd = N+1
240 #include "llvm/Instruction.def"
244 #define FIRST_CAST_INST(N) CastOpsBegin = N,
245 #define HANDLE_CAST_INST(N, OPC, CLASS) OPC = N,
246 #define LAST_CAST_INST(N) CastOpsEnd = N+1
247 #include "llvm/Instruction.def"
251 #define FIRST_OTHER_INST(N) OtherOpsBegin = N,
252 #define HANDLE_OTHER_INST(N, OPC, CLASS) OPC = N,
253 #define LAST_OTHER_INST(N) OtherOpsEnd = N+1
254 #include "llvm/Instruction.def"
258 // Instruction* is only 4-byte aligned.
260 class PointerLikeTypeTraits<Instruction*> {
261 typedef Instruction* PT;
263 static inline void *getAsVoidPointer(PT P) { return P; }
264 static inline PT getFromVoidPointer(void *P) {
265 return static_cast<PT>(P);
267 enum { NumLowBitsAvailable = 2 };
270 } // End llvm namespace