class SymbolTableListTraits;
class Instruction : public User, public ilist_node<Instruction> {
- void operator=(const Instruction &); // Do not implement
- Instruction(const Instruction &); // Do not implement
+ void operator=(const Instruction &) LLVM_DELETED_FUNCTION;
+ Instruction(const Instruction &) LLVM_DELETED_FUNCTION;
BasicBlock *Parent;
DebugLoc DbgLoc; // 'dbg' Metadata cache.
bool isCommutative() const { return isCommutative(getOpcode()); }
static bool isCommutative(unsigned op);
+ /// isIdempotent - Return true if the instruction is idempotent:
+ ///
+ /// Idempotent operators satisfy: x op x === x
+ ///
+ /// In LLVM, the And and Or operators are idempotent.
+ ///
+ bool isIdempotent() const { return isIdempotent(getOpcode()); }
+ static bool isIdempotent(unsigned op);
+
+ /// isNilpotent - Return true if the instruction is nilpotent:
+ ///
+ /// Nilpotent operators satisfy: x op x === Id,
+ ///
+ /// where Id is the identity for the operator, i.e. a constant such that
+ /// x op Id === x and Id op x === x for all x.
+ ///
+ /// In LLVM, the Xor operator is nilpotent.
+ ///
+ bool isNilpotent() const { return isNilpotent(getOpcode()); }
+ static bool isNilpotent(unsigned op);
+
/// mayWriteToMemory - Return true if this instruction may modify memory.
///
bool mayWriteToMemory() const;
return mayWriteToMemory() || mayThrow();
}
- /// isSafeToSpeculativelyExecute - Return true if the instruction does not
- /// have any effects besides calculating the result and does not have
- /// undefined behavior.
- ///
- /// This method never returns true for an instruction that returns true for
- /// mayHaveSideEffects; however, this method also does some other checks in
- /// addition. It checks for undefined behavior, like dividing by zero or
- /// loading from an invalid pointer (but not for undefined results, like a
- /// shift with a shift amount larger than the width of the result). It checks
- /// for malloc and alloca because speculatively executing them might cause a
- /// memory leak. It also returns false for instructions related to control
- /// flow, specifically terminators and PHI nodes.
- ///
- /// This method only looks at the instruction itself and its operands, so if
- /// this method returns true, it is safe to move the instruction as long as
- /// the correct dominance relationships for the operands and users hold.
- /// However, this method can return true for instructions that read memory;
- /// for such instructions, moving them may change the resulting value.
- bool isSafeToSpeculativelyExecute() const;
-
/// clone() - Create a copy of 'this' instruction that is identical in all
/// ways except the following:
/// * The instruction has no parent
/// ignores the SubclassOptionalData flags, which specify conditions
/// under which the instruction's result is undefined.
bool isIdenticalToWhenDefined(const Instruction *I) const;
+
+ /// When checking for operation equivalence (using isSameOperationAs) it is
+ /// sometimes useful to ignore certain attributes.
+ enum OperationEquivalenceFlags {
+ /// Check for equivalence ignoring load/store alignment.
+ CompareIgnoringAlignment = 1<<0,
+ /// Check for equivalence treating a type and a vector of that type
+ /// as equivalent.
+ CompareUsingScalarTypes = 1<<1
+ };
/// This function determines if the specified instruction executes the same
/// operation as the current one. This means that the opcodes, type, operand
/// @returns true if the specified instruction is the same operation as
/// the current one.
/// @brief Determine if one instruction is the same operation as another.
- bool isSameOperationAs(const Instruction *I) const;
+ bool isSameOperationAs(const Instruction *I, unsigned flags = 0) const;
/// isUsedOutsideOfBlock - Return true if there are any uses of this
/// instruction in blocks other than the specified block. Note that PHI nodes
/// Methods for support type inquiry through isa, cast, and dyn_cast:
- static inline bool classof(const Instruction *) { return true; }
static inline bool classof(const Value *V) {
return V->getValueID() >= Value::InstructionVal;
}