Instruction.h
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Instruction.h
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	//===-- llvm/Instruction.h - Instruction class definition -------- C++ --===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This file contains the declaration of the Instruction class, which is the
	// base class for all of the LLVM instructions.
	//
	//===----------------------------------------------------------------------===//

	#ifndef LLVM_IR_INSTRUCTION_H
	#define LLVM_IR_INSTRUCTION_H

	#include "llvm/ADT/ArrayRef.h"
	#include "llvm/ADT/None.h"
	#include "llvm/ADT/StringRef.h"
	#include "llvm/ADT/ilist_node.h"
	#include "llvm/IR/DebugLoc.h"
	#include "llvm/IR/SymbolTableListTraits.h"
	#include "llvm/IR/User.h"
	#include "llvm/IR/Value.h"
	#include "llvm/Support/Casting.h"
	#include <algorithm>
	#include <cassert>
	#include <cstdint>
	#include <utility>

	namespace llvm {

	class BasicBlock;
	class FastMathFlags;
	class MDNode;
	struct AAMDNodes;

	template <> struct ilist_alloc_traits<Instruction> {
	static inline void deleteNode(Instruction *V);
	};

	class Instruction : public User,
	public ilist_node_with_parent<Instruction, BasicBlock> {
	BasicBlock *Parent;
	DebugLoc DbgLoc; // 'dbg' Metadata cache.

	enum {
	/// This is a bit stored in the SubClassData field which indicates whether
	/// this instruction has metadata attached to it or not.
	HasMetadataBit = 1 << 15
	};

	protected:
	~Instruction(); // Use deleteValue() to delete a generic Instruction.

	public:
	Instruction(const Instruction &) = delete;
	Instruction &operator=(const Instruction &) = delete;

	/// Specialize the methods defined in Value, as we know that an instruction
	/// can only be used by other instructions.
	Instruction user_back() { return cast<Instruction>(user_begin());}
	const Instruction user_back() const { return cast<Instruction>(user_begin());}

	inline const BasicBlock *getParent() const { return Parent; }
	inline BasicBlock *getParent() { return Parent; }

	/// Return the module owning the function this instruction belongs to
	/// or nullptr it the function does not have a module.
	///
	/// Note: this is undefined behavior if the instruction does not have a
	/// parent, or the parent basic block does not have a parent function.
	const Module *getModule() const;
	Module *getModule() {
	return const_cast<Module *>(
	static_cast<const Instruction *>(this)->getModule());
	}

	/// Return the function this instruction belongs to.
	///
	/// Note: it is undefined behavior to call this on an instruction not
	/// currently inserted into a function.
	const Function *getFunction() const;
	Function *getFunction() {
	return const_cast<Function *>(
	static_cast<const Instruction *>(this)->getFunction());
	}

	/// This method unlinks 'this' from the containing basic block, but does not
	/// delete it.
	void removeFromParent();

	/// This method unlinks 'this' from the containing basic block and deletes it.
	///
	/// \returns an iterator pointing to the element after the erased one
	SymbolTableList<Instruction>::iterator eraseFromParent();

	/// Insert an unlinked instruction into a basic block immediately before
	/// the specified instruction.
	void insertBefore(Instruction *InsertPos);

	/// Insert an unlinked instruction into a basic block immediately after the
	/// specified instruction.
	void insertAfter(Instruction *InsertPos);

	/// Unlink this instruction from its current basic block and insert it into
	/// the basic block that MovePos lives in, right before MovePos.
	void moveBefore(Instruction *MovePos);

	/// Unlink this instruction and insert into BB before I.
	///
	/// \pre I is a valid iterator into BB.
	void moveBefore(BasicBlock &BB, SymbolTableList<Instruction>::iterator I);

	//===--------------------------------------------------------------------===//
	// Subclass classification.
	//===--------------------------------------------------------------------===//

	/// Returns a member of one of the enums like Instruction::Add.
	unsigned getOpcode() const { return getValueID() - InstructionVal; }

	const char *getOpcodeName() const { return getOpcodeName(getOpcode()); }
	bool isTerminator() const { return isTerminator(getOpcode()); }
	bool isBinaryOp() const { return isBinaryOp(getOpcode()); }
	bool isShift() { return isShift(getOpcode()); }
	bool isCast() const { return isCast(getOpcode()); }
	bool isFuncletPad() const { return isFuncletPad(getOpcode()); }

	static const char* getOpcodeName(unsigned OpCode);

	static inline bool isTerminator(unsigned OpCode) {
	return OpCode >= TermOpsBegin && OpCode < TermOpsEnd;
	}

	static inline bool isBinaryOp(unsigned Opcode) {
	return Opcode >= BinaryOpsBegin && Opcode < BinaryOpsEnd;
	}

	/// Determine if the Opcode is one of the shift instructions.
	static inline bool isShift(unsigned Opcode) {
	return Opcode >= Shl && Opcode <= AShr;
	}

	/// Return true if this is a logical shift left or a logical shift right.
	inline bool isLogicalShift() const {
	return getOpcode() == Shl \|\| getOpcode() == LShr;
	}

	/// Return true if this is an arithmetic shift right.
	inline bool isArithmeticShift() const {
	return getOpcode() == AShr;
	}

	/// Determine if the Opcode is and/or/xor.
	static inline bool isBitwiseLogicOp(unsigned Opcode) {
	return Opcode == And \|\| Opcode == Or \|\| Opcode == Xor;
	}

	/// Return true if this is and/or/xor.
	inline bool isBitwiseLogicOp() const {
	return isBitwiseLogicOp(getOpcode());
	}

	/// Determine if the OpCode is one of the CastInst instructions.
	static inline bool isCast(unsigned OpCode) {
	return OpCode >= CastOpsBegin && OpCode < CastOpsEnd;
	}

	/// Determine if the OpCode is one of the FuncletPadInst instructions.
	static inline bool isFuncletPad(unsigned OpCode) {
	return OpCode >= FuncletPadOpsBegin && OpCode < FuncletPadOpsEnd;
	}

	//===--------------------------------------------------------------------===//
	// Metadata manipulation.
	//===--------------------------------------------------------------------===//

	/// Return true if this instruction has any metadata attached to it.
	bool hasMetadata() const { return DbgLoc \|\| hasMetadataHashEntry(); }

	/// Return true if this instruction has metadata attached to it other than a
	/// debug location.
	bool hasMetadataOtherThanDebugLoc() const {
	return hasMetadataHashEntry();
	}

	/// Get the metadata of given kind attached to this Instruction.
	/// If the metadata is not found then return null.
	MDNode *getMetadata(unsigned KindID) const {
	if (!hasMetadata()) return nullptr;
	return getMetadataImpl(KindID);
	}

	/// Get the metadata of given kind attached to this Instruction.
	/// If the metadata is not found then return null.
	MDNode *getMetadata(StringRef Kind) const {
	if (!hasMetadata()) return nullptr;
	return getMetadataImpl(Kind);
	}

	/// Get all metadata attached to this Instruction. The first element of each
	/// pair returned is the KindID, the second element is the metadata value.
	/// This list is returned sorted by the KindID.
	void
	getAllMetadata(SmallVectorImpl<std::pair<unsigned, MDNode *>> &MDs) const {
	if (hasMetadata())
	getAllMetadataImpl(MDs);
	}

	/// This does the same thing as getAllMetadata, except that it filters out the
	/// debug location.
	void getAllMetadataOtherThanDebugLoc(
	SmallVectorImpl<std::pair<unsigned, MDNode *>> &MDs) const {
	if (hasMetadataOtherThanDebugLoc())
	getAllMetadataOtherThanDebugLocImpl(MDs);
	}

	/// Fills the AAMDNodes structure with AA metadata from this instruction.
	/// When Merge is true, the existing AA metadata is merged with that from this
	/// instruction providing the most-general result.
	void getAAMetadata(AAMDNodes &N, bool Merge = false) const;

	/// Set the metadata of the specified kind to the specified node. This updates
	/// or replaces metadata if already present, or removes it if Node is null.
	void setMetadata(unsigned KindID, MDNode *Node);
	void setMetadata(StringRef Kind, MDNode *Node);

	/// Copy metadata from \p SrcInst to this instruction. \p WL, if not empty,
	/// specifies the list of meta data that needs to be copied. If \p WL is
	/// empty, all meta data will be copied.
	void copyMetadata(const Instruction &SrcInst,
	ArrayRef<unsigned> WL = ArrayRef<unsigned>());

	/// If the instruction has "branch_weights" MD_prof metadata and the MDNode
	/// has three operands (including name string), swap the order of the
	/// metadata.
	void swapProfMetadata();

	/// Drop all unknown metadata except for debug locations.
	/// @{
	/// Passes are required to drop metadata they don't understand. This is a
	/// convenience method for passes to do so.
	void dropUnknownNonDebugMetadata(ArrayRef<unsigned> KnownIDs);
	void dropUnknownNonDebugMetadata() {
	return dropUnknownNonDebugMetadata(None);
	}
	void dropUnknownNonDebugMetadata(unsigned ID1) {
	return dropUnknownNonDebugMetadata(makeArrayRef(ID1));
	}
	void dropUnknownNonDebugMetadata(unsigned ID1, unsigned ID2) {
	unsigned IDs[] = {ID1, ID2};
	return dropUnknownNonDebugMetadata(IDs);
	}
	/// @}

	/// Sets the metadata on this instruction from the AAMDNodes structure.
	void setAAMetadata(const AAMDNodes &N);

	/// Retrieve the raw weight values of a conditional branch or select.
	/// Returns true on success with profile weights filled in.
	/// Returns false if no metadata or invalid metadata was found.
	bool extractProfMetadata(uint64_t &TrueVal, uint64_t &FalseVal) const;

	/// Retrieve total raw weight values of a branch.
	/// Returns true on success with profile total weights filled in.
	/// Returns false if no metadata was found.
	bool extractProfTotalWeight(uint64_t &TotalVal) const;

	/// Updates branch_weights metadata by scaling it by \p S / \p T.
	void updateProfWeight(uint64_t S, uint64_t T);

	/// Sets the branch_weights metadata to \p W for CallInst.
	void setProfWeight(uint64_t W);

	/// Set the debug location information for this instruction.
	void setDebugLoc(DebugLoc Loc) { DbgLoc = std::move(Loc); }

	/// Return the debug location for this node as a DebugLoc.
	const DebugLoc &getDebugLoc() const { return DbgLoc; }

	/// Set or clear the nsw flag on this instruction, which must be an operator
	/// which supports this flag. See LangRef.html for the meaning of this flag.
	void setHasNoUnsignedWrap(bool b = true);

	/// Set or clear the nsw flag on this instruction, which must be an operator
	/// which supports this flag. See LangRef.html for the meaning of this flag.
	void setHasNoSignedWrap(bool b = true);

	/// Set or clear the exact flag on this instruction, which must be an operator
	/// which supports this flag. See LangRef.html for the meaning of this flag.
	void setIsExact(bool b = true);

	/// Determine whether the no unsigned wrap flag is set.
	bool hasNoUnsignedWrap() const;

	/// Determine whether the no signed wrap flag is set.
	bool hasNoSignedWrap() const;

	/// Drops flags that may cause this instruction to evaluate to poison despite
	/// having non-poison inputs.
	void dropPoisonGeneratingFlags();

	/// Determine whether the exact flag is set.
	bool isExact() const;

	/// Set or clear the unsafe-algebra flag on this instruction, which must be an
	/// operator which supports this flag. See LangRef.html for the meaning of
	/// this flag.
	void setHasUnsafeAlgebra(bool B);

	/// Set or clear the no-nans flag on this instruction, which must be an
	/// operator which supports this flag. See LangRef.html for the meaning of
	/// this flag.
	void setHasNoNaNs(bool B);

	/// Set or clear the no-infs flag on this instruction, which must be an
	/// operator which supports this flag. See LangRef.html for the meaning of
	/// this flag.
	void setHasNoInfs(bool B);

	/// Set or clear the no-signed-zeros flag on this instruction, which must be
	/// an operator which supports this flag. See LangRef.html for the meaning of
	/// this flag.
	void setHasNoSignedZeros(bool B);

	/// Set or clear the allow-reciprocal flag on this instruction, which must be
	/// an operator which supports this flag. See LangRef.html for the meaning of
	/// this flag.
	void setHasAllowReciprocal(bool B);

	/// Convenience function for setting multiple fast-math flags on this
	/// instruction, which must be an operator which supports these flags. See
	/// LangRef.html for the meaning of these flags.
	void setFastMathFlags(FastMathFlags FMF);

	/// Convenience function for transferring all fast-math flag values to this
	/// instruction, which must be an operator which supports these flags. See
	/// LangRef.html for the meaning of these flags.
	void copyFastMathFlags(FastMathFlags FMF);

	/// Determine whether the unsafe-algebra flag is set.
	bool hasUnsafeAlgebra() const;

	/// Determine whether the no-NaNs flag is set.
	bool hasNoNaNs() const;

	/// Determine whether the no-infs flag is set.
	bool hasNoInfs() const;

	/// Determine whether the no-signed-zeros flag is set.
	bool hasNoSignedZeros() const;

	/// Determine whether the allow-reciprocal flag is set.
	bool hasAllowReciprocal() const;

	/// Determine whether the allow-contract flag is set.
	bool hasAllowContract() const;

	/// Convenience function for getting all the fast-math flags, which must be an
	/// operator which supports these flags. See LangRef.html for the meaning of
	/// these flags.
	FastMathFlags getFastMathFlags() const;

	/// Copy I's fast-math flags
	void copyFastMathFlags(const Instruction *I);

	/// Convenience method to copy supported exact, fast-math, and (optionally)
	/// wrapping flags from V to this instruction.
	void copyIRFlags(const Value *V, bool IncludeWrapFlags = true);

	/// Logical 'and' of any supported wrapping, exact, and fast-math flags of
	/// V and this instruction.
	void andIRFlags(const Value *V);

	private:
	/// Return true if we have an entry in the on-the-side metadata hash.
	bool hasMetadataHashEntry() const {
	return (getSubclassDataFromValue() & HasMetadataBit) != 0;
	}

	// These are all implemented in Metadata.cpp.
	MDNode *getMetadataImpl(unsigned KindID) const;
	MDNode *getMetadataImpl(StringRef Kind) const;
	void
	getAllMetadataImpl(SmallVectorImpl<std::pair<unsigned, MDNode *>> &) const;
	void getAllMetadataOtherThanDebugLocImpl(
	SmallVectorImpl<std::pair<unsigned, MDNode *>> &) const;
	/// Clear all hashtable-based metadata from this instruction.
	void clearMetadataHashEntries();

	public:
	//===--------------------------------------------------------------------===//
	// Predicates and helper methods.
	//===--------------------------------------------------------------------===//

	/// Return true if the instruction is associative:
	///
	/// Associative operators satisfy: x op (y op z) === (x op y) op z
	///
	/// In LLVM, the Add, Mul, And, Or, and Xor operators are associative.
	///
	bool isAssociative() const LLVM_READONLY;
	static bool isAssociative(unsigned Opcode) {
	return Opcode == And \|\| Opcode == Or \|\| Opcode == Xor \|\|
	Opcode == Add \|\| Opcode == Mul;
	}

	/// Return true if the instruction is commutative:
	///
	/// Commutative operators satisfy: (x op y) === (y op x)
	///
	/// In LLVM, these are the commutative operators, plus SetEQ and SetNE, when
	/// applied to any type.
	///
	bool isCommutative() const { return isCommutative(getOpcode()); }
	static bool isCommutative(unsigned Opcode) {
	switch (Opcode) {
	case Add: case FAdd:
	case Mul: case FMul:
	case And: case Or: case Xor:
	return true;
	default:
	return false;
	}
	}

	/// 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 Opcode) {
	return Opcode == And \|\| Opcode == Or;
	}

	/// 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 Opcode) {
	return Opcode == Xor;
	}

	/// Return true if this instruction may modify memory.
	bool mayWriteToMemory() const;

	/// Return true if this instruction may read memory.
	bool mayReadFromMemory() const;

	/// Return true if this instruction may read or write memory.
	bool mayReadOrWriteMemory() const {
	return mayReadFromMemory() \|\| mayWriteToMemory();
	}

	/// Return true if this instruction has an AtomicOrdering of unordered or
	/// higher.
	bool isAtomic() const;

	/// Return true if this atomic instruction loads from memory.
	bool hasAtomicLoad() const;

	/// Return true if this atomic instruction stores to memory.
	bool hasAtomicStore() const;

	/// Return true if this instruction may throw an exception.
	bool mayThrow() const;

	/// Return true if this instruction behaves like a memory fence: it can load
	/// or store to memory location without being given a memory location.
	bool isFenceLike() const {
	switch (getOpcode()) {
	default:
	return false;
	// This list should be kept in sync with the list in mayWriteToMemory for
	// all opcodes which don't have a memory location.
	case Instruction::Fence:
	case Instruction::CatchPad:
	case Instruction::CatchRet:
	case Instruction::Call:
	case Instruction::Invoke:
	return true;
	}
	}

	/// Return true if the instruction may have side effects.
	///
	/// Note that this does not consider malloc and alloca to have side
	/// effects because the newly allocated memory is completely invisible to
	/// instructions which don't use the returned value. For cases where this
	/// matters, isSafeToSpeculativelyExecute may be more appropriate.
	bool mayHaveSideEffects() const { return mayWriteToMemory() \|\| mayThrow(); }

	/// Return true if the instruction is a variety of EH-block.
	bool isEHPad() const {
	switch (getOpcode()) {
	case Instruction::CatchSwitch:
	case Instruction::CatchPad:
	case Instruction::CleanupPad:
	case Instruction::LandingPad:
	return true;
	default:
	return false;
	}
	}

	/// Create a copy of 'this' instruction that is identical in all ways except
	/// the following:
	/// * The instruction has no parent
	/// * The instruction has no name
	///
	Instruction *clone() const;

	/// Return true if the specified instruction is exactly identical to the
	/// current one. This means that all operands match and any extra information
	/// (e.g. load is volatile) agree.
	bool isIdenticalTo(const Instruction *I) const;

	/// This is like isIdenticalTo, except that it ignores the
	/// SubclassOptionalData flags, which may 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
	/// types and any other factors affecting the operation must be the same. This
	/// is similar to isIdenticalTo except the operands themselves don't have to
	/// be identical.
	/// @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, unsigned flags = 0) const;

	/// Return true if there are any uses of this instruction in blocks other than
	/// the specified block. Note that PHI nodes are considered to evaluate their
	/// operands in the corresponding predecessor block.
	bool isUsedOutsideOfBlock(const BasicBlock *BB) const;


	/// Methods for support type inquiry through isa, cast, and dyn_cast:
	static bool classof(const Value *V) {
	return V->getValueID() >= Value::InstructionVal;
	}

	//----------------------------------------------------------------------
	// Exported enumerations.
	//
	enum TermOps { // These terminate basic blocks
	#define FIRST_TERM_INST(N) TermOpsBegin = N,
	#define HANDLE_TERM_INST(N, OPC, CLASS) OPC = N,
	#define LAST_TERM_INST(N) TermOpsEnd = N+1
	#include "llvm/IR/Instruction.def"
	};

	enum BinaryOps {
	#define FIRST_BINARY_INST(N) BinaryOpsBegin = N,
	#define HANDLE_BINARY_INST(N, OPC, CLASS) OPC = N,
	#define LAST_BINARY_INST(N) BinaryOpsEnd = N+1
	#include "llvm/IR/Instruction.def"
	};

	enum MemoryOps {
	#define FIRST_MEMORY_INST(N) MemoryOpsBegin = N,
	#define HANDLE_MEMORY_INST(N, OPC, CLASS) OPC = N,
	#define LAST_MEMORY_INST(N) MemoryOpsEnd = N+1
	#include "llvm/IR/Instruction.def"
	};

	enum CastOps {
	#define FIRST_CAST_INST(N) CastOpsBegin = N,
	#define HANDLE_CAST_INST(N, OPC, CLASS) OPC = N,
	#define LAST_CAST_INST(N) CastOpsEnd = N+1
	#include "llvm/IR/Instruction.def"
	};

	enum FuncletPadOps {
	#define FIRST_FUNCLETPAD_INST(N) FuncletPadOpsBegin = N,
	#define HANDLE_FUNCLETPAD_INST(N, OPC, CLASS) OPC = N,
	#define LAST_FUNCLETPAD_INST(N) FuncletPadOpsEnd = N+1
	#include "llvm/IR/Instruction.def"
	};

	enum OtherOps {
	#define FIRST_OTHER_INST(N) OtherOpsBegin = N,
	#define HANDLE_OTHER_INST(N, OPC, CLASS) OPC = N,
	#define LAST_OTHER_INST(N) OtherOpsEnd = N+1
	#include "llvm/IR/Instruction.def"
	};

	private:
	friend class SymbolTableListTraits<Instruction>;

	// Shadow Value::setValueSubclassData with a private forwarding method so that
	// subclasses cannot accidentally use it.
	void setValueSubclassData(unsigned short D) {
	Value::setValueSubclassData(D);
	}

	unsigned short getSubclassDataFromValue() const {
	return Value::getSubclassDataFromValue();
	}

	void setHasMetadataHashEntry(bool V) {
	setValueSubclassData((getSubclassDataFromValue() & ~HasMetadataBit) \|
	(V ? HasMetadataBit : 0));
	}

	void setParent(BasicBlock *P);

	protected:
	// Instruction subclasses can stick up to 15 bits of stuff into the
	// SubclassData field of instruction with these members.

	// Verify that only the low 15 bits are used.
	void setInstructionSubclassData(unsigned short D) {
	assert((D & HasMetadataBit) == 0 && "Out of range value put into field");
	setValueSubclassData((getSubclassDataFromValue() & HasMetadataBit) \| D);
	}

	unsigned getSubclassDataFromInstruction() const {
	return getSubclassDataFromValue() & ~HasMetadataBit;
	}

	Instruction(Type Ty, unsigned iType, Use Ops, unsigned NumOps,
	Instruction *InsertBefore = nullptr);
	Instruction(Type Ty, unsigned iType, Use Ops, unsigned NumOps,
	BasicBlock *InsertAtEnd);

	private:
	/// Create a copy of this instruction.
	Instruction *cloneImpl() const;
	};

	inline void ilist_alloc_traits<Instruction>::deleteNode(Instruction *V) {
	V->deleteValue();
	}

	} // end namespace llvm

	#endif // LLVM_IR_INSTRUCTION_H

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