Value.h

Go to the documentation of this file.

//===- Value.h - Base of the SSA Value hierarchy ----------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines generic Value type and manipulation utilities.
//
//===----------------------------------------------------------------------===//
 
#ifndef MLIR_IR_VALUE_H
#define MLIR_IR_VALUE_H
 
#include "mlir/IR/Types.h"
#include "mlir/IR/UseDefLists.h"
#include "mlir/Support/LLVM.h"
#include "llvm/Support/PointerLikeTypeTraits.h"
 
namespace mlir {
class AsmState;
class Block;
class BlockArgument;
class Operation;
class OpOperand;
class OpPrintingFlags;
class OpResult;
class Region;
class Value;
 
//===----------------------------------------------------------------------===//
// Value
//===----------------------------------------------------------------------===//
 
namespace detail {
 
/// The base class for all derived Value classes. It contains all of the
/// components that are shared across Value classes.
class alignas(8) ValueImpl : public IRObjectWithUseList<OpOperand> {
public:
  /// The enumeration represents the various different kinds of values the
  /// internal representation may take. We use all of the bits from Type that we
  /// can to store indices inline.
  enum class Kind {
    /// The first N kinds are all inline operation results. An inline operation
    /// result means that the kind represents the result number. This removes
    /// the need to store an additional index value. The derived class here is
    /// an `OpResultImpl`.
    InlineOpResult = 0,
 
    /// The next kind represents a 'out-of-line' operation result. This is for
    /// results with numbers larger than we can represent inline. The derived
    /// class here is an `OpResultImpl`.
    OutOfLineOpResult = 6,
 
    /// The last kind represents a block argument. The derived class here is an
    /// `BlockArgumentImpl`.
    BlockArgument = 7
  };
 
  /// Return the type of this value.
  Type getType() const { return typeAndKind.getPointer(); }
 
  /// Set the type of this value.
  void setType(Type type) { return typeAndKind.setPointer(type); }
 
  /// Return the kind of this value.
  Kind getKind() const { return typeAndKind.getInt(); }
 
protected:
  ValueImpl(Type type, Kind kind) : typeAndKind(type, kind) {}
 
  /// Expose a few methods explicitly for the debugger to call for
  /// visualization.
#ifndef NDEBUG
  LLVM_DUMP_METHOD Type debug_getType() const { return getType(); }
  LLVM_DUMP_METHOD Kind debug_getKind() const { return getKind(); }
 
#endif
 
  /// The type of this result and the kind.
  llvm::PointerIntPair<Type, 3, Kind> typeAndKind;
};
} // namespace detail
 
/// This class represents an instance of an SSA value in the MLIR system,
/// representing a computable value that has a type and a set of users. An SSA
/// value is either a BlockArgument or the result of an operation. Note: This
/// class has value-type semantics and is just a simple wrapper around a
/// ValueImpl that is either owner by a block(in the case of a BlockArgument) or
/// an Operation(in the case of an OpResult).
/// As most IR constructs, this isn't const-correct, but we keep method
/// consistent and as such method that immediately modify this Value aren't
/// marked `const` (include modifying the Value use-list).
class Value {
public:
  constexpr Value(detail::ValueImpl *impl = nullptr) : impl(impl) {}
 
  explicit operator bool() const { return impl; }
  bool operator==(const Value &other) const { return impl == other.impl; }
  bool operator!=(const Value &other) const { return !(*this == other); }
 
  /// Return the type of this value.
  Type getType() const { return impl->getType(); }
 
  /// Utility to get the associated MLIRContext that this value is defined in.
  MLIRContext *getContext() const { return getType().getContext(); }
 
  /// Mutate the type of this Value to be of the specified type.
  ///
  /// Note that this is an extremely dangerous operation which can create
  /// completely invalid IR very easily.  It is strongly recommended that you
  /// recreate IR objects with the right types instead of mutating them in
  /// place.
  void setType(Type newType) { impl->setType(newType); }
 
  /// If this value is the result of an operation, return the operation that
  /// defines it.
  Operation *getDefiningOp() const;
 
  /// If this value is the result of an operation of type OpTy, return the
  /// operation that defines it.
  template <typename OpTy>
  OpTy getDefiningOp() const {
    return llvm::dyn_cast_or_null<OpTy>(getDefiningOp());
  }
 
  /// Return the location of this value.
  Location getLoc() const;
  void setLoc(Location loc);
 
  /// Return the Region in which this Value is defined.
  Region *getParentRegion();
 
  /// Return the Block in which this Value is defined.
  Block *getParentBlock();
 
  //===--------------------------------------------------------------------===//
  // UseLists
  //===--------------------------------------------------------------------===//
 
  /// Drop all uses of this object from their respective owners.
  void dropAllUses() { return impl->dropAllUses(); }
 
  /// Replace all uses of 'this' value with the new value, updating anything in
  /// the IR that uses 'this' to use the other value instead.  When this returns
  /// there are zero uses of 'this'.
  void replaceAllUsesWith(Value newValue) {
    impl->replaceAllUsesWith(newValue);
  }
 
  /// Replace all uses of 'this' value with 'newValue', updating anything in the
  /// IR that uses 'this' to use the other value instead except if the user is
  /// listed in 'exceptions' .
  void replaceAllUsesExcept(Value newValue,
                            const SmallPtrSetImpl<Operation *> &exceptions);
 
  /// Replace all uses of 'this' value with 'newValue', updating anything in the
  /// IR that uses 'this' to use the other value instead except if the user is
  /// 'exceptedUser'.
  void replaceAllUsesExcept(Value newValue, Operation *exceptedUser);
 
  /// Replace all uses of 'this' value with 'newValue' if the given callback
  /// returns true.
  void replaceUsesWithIf(Value newValue,
                         function_ref<bool(OpOperand &)> shouldReplace);
 
  /// Returns true if the value is used outside of the given block.
  bool isUsedOutsideOfBlock(Block *block) const;
 
  /// Shuffle the use list order according to the provided indices. It is
  /// responsibility of the caller to make sure that the indices map the current
  /// use-list chain to another valid use-list chain.
  void shuffleUseList(ArrayRef<unsigned> indices);
 
  //===--------------------------------------------------------------------===//
  // Uses
 
  /// This class implements an iterator over the uses of a value.
  using use_iterator = ValueUseIterator<OpOperand>;
  using use_range = iterator_range<use_iterator>;
 
  use_iterator use_begin() const { return impl->use_begin(); }
  use_iterator use_end() const { return use_iterator(); }
 
  /// Returns a range of all uses, which is useful for iterating over all uses.
  use_range getUses() const { return {use_begin(), use_end()}; }
 
  /// This method computes the number of uses of this Value.
  ///
  /// This is a linear time operation.  Use hasOneUse, hasNUses, or
  /// hasNUsesOrMore to check for specific values.
  unsigned getNumUses() const;
 
  /// Returns true if this value has exactly one use.
  bool hasOneUse() const { return impl->hasOneUse(); }
 
  /// Return true if this Value has exactly n uses.
  bool hasNUses(unsigned n) const;
 
  /// Return true if this value has n uses or more.
  ///
  /// This is logically equivalent to getNumUses() >= N.
  bool hasNUsesOrMore(unsigned n) const;
 
  /// Returns true if this value has no uses.
  bool use_empty() const { return impl->use_empty(); }
 
  //===--------------------------------------------------------------------===//
  // Users
 
  using user_iterator = ValueUserIterator<use_iterator, OpOperand>;
  using user_range = iterator_range<user_iterator>;
 
  user_iterator user_begin() const { return use_begin(); }
  user_iterator user_end() const { return use_end(); }
  user_range getUsers() const { return {user_begin(), user_end()}; }
 
  //===--------------------------------------------------------------------===//
  // Utilities
 
  void print(raw_ostream &os) const;
  void print(raw_ostream &os, const OpPrintingFlags &flags) const;
  void print(raw_ostream &os, AsmState &state) const;
  void dump() const;
 
  /// Print this value as if it were an operand.
  void printAsOperand(raw_ostream &os, AsmState &state) const;
  void printAsOperand(raw_ostream &os, const OpPrintingFlags &flags) const;
 
  /// Methods for supporting PointerLikeTypeTraits.
  void *getAsOpaquePointer() const { return impl; }
  static Value getFromOpaquePointer(const void *pointer) {
    return reinterpret_cast<detail::ValueImpl *>(const_cast<void *>(pointer));
  }
  detail::ValueImpl *getImpl() const { return impl; }
 
  friend ::llvm::hash_code hash_value(Value arg);
 
protected:
  /// A pointer to the internal implementation of the value.
  detail::ValueImpl *impl;
};
 
inline raw_ostream &operator<<(raw_ostream &os, Value value) {
  value.print(os);
  return os;
}
 
//===----------------------------------------------------------------------===//
// OpOperand
//===----------------------------------------------------------------------===//
 
/// This class represents an operand of an operation. Instances of this class
/// contain a reference to a specific `Value`.
class OpOperand : public IROperand<OpOperand, Value> {
public:
  /// Provide the use list that is attached to the given value.
  static IRObjectWithUseList<OpOperand> *getUseList(Value value) {
    return value.getImpl();
  }
 
  /// Return which operand this is in the OpOperand list of the Operation.
  unsigned getOperandNumber();
 
  /// Set the current value being used by this operand.
  void assign(Value value) { set(value); }
 
private:
  /// Keep the constructor private and accessible to the OperandStorage class
  /// only to avoid hard-to-debug typo/programming mistakes.
  friend class OperandStorage;
  using IROperand<OpOperand, Value>::IROperand;
};
 
//===----------------------------------------------------------------------===//
// BlockArgument
//===----------------------------------------------------------------------===//
 
namespace detail {
/// The internal implementation of a BlockArgument.
class BlockArgumentImpl : public ValueImpl {
public:
  static bool classof(const ValueImpl *value) {
    return value->getKind() == ValueImpl::Kind::BlockArgument;
  }
 
private:
  BlockArgumentImpl(Type type, Block *owner, int64_t index, Location loc)
      : ValueImpl(type, Kind::BlockArgument), owner(owner), index(index),
        loc(loc) {}
 
  /// The owner of this argument.
  Block *owner;
 
  /// The position in the argument list.
  int64_t index;
 
  /// The source location of this argument.
  Location loc;
 
  /// Allow access to owner and constructor.
  friend BlockArgument;
};
} // namespace detail
 
/// This class represents an argument of a Block.
class BlockArgument : public Value {
public:
  using Value::Value;
 
  static bool classof(Value value) {
    return llvm::isa<detail::BlockArgumentImpl>(value.getImpl());
  }
 
  /// Returns the block that owns this argument.
  Block *getOwner() const { return getImpl()->owner; }
 
  /// Returns the number of this argument.
  unsigned getArgNumber() const { return getImpl()->index; }
 
  /// Return the location for this argument.
  Location getLoc() const { return getImpl()->loc; }
  void setLoc(Location loc) { getImpl()->loc = loc; }
 
private:
  /// Allocate a new argument with the given type and owner.
  static BlockArgument create(Type type, Block *owner, int64_t index,
                              Location loc) {
    return new detail::BlockArgumentImpl(type, owner, index, loc);
  }
 
  /// Destroy and deallocate this argument.
  void destroy() { delete getImpl(); }
 
  /// Get a raw pointer to the internal implementation.
  detail::BlockArgumentImpl *getImpl() const {
    return reinterpret_cast<detail::BlockArgumentImpl *>(impl);
  }
 
  /// Cache the position in the block argument list.
  void setArgNumber(int64_t index) { getImpl()->index = index; }
 
  /// Allow access to `create`, `destroy` and `setArgNumber`.
  friend Block;
 
  /// Allow access to 'getImpl'.
  friend Value;
};
 
//===----------------------------------------------------------------------===//
// OpResult
//===----------------------------------------------------------------------===//
 
namespace detail {
/// This class provides the implementation for an operation result.
class alignas(8) OpResultImpl : public ValueImpl {
public:
  using ValueImpl::ValueImpl;
 
  static bool classof(const ValueImpl *value) {
    return value->getKind() != ValueImpl::Kind::BlockArgument;
  }
 
  /// Returns the parent operation of this result.
  Operation *getOwner() const;
 
  /// Returns the result number of this op result.
  unsigned getResultNumber() const;
 
  /// Returns the next operation result at `offset` after this result. This
  /// method is useful when indexing the result storage of an operation, given
  /// that there is more than one kind of operation result (with the different
  /// kinds having different sizes) and that operations are stored in reverse
  /// order.
  OpResultImpl *getNextResultAtOffset(intptr_t offset);
 
  /// Returns the maximum number of results that can be stored inline.
  static unsigned getMaxInlineResults() {
    return static_cast<unsigned>(Kind::OutOfLineOpResult);
  }
};
 
/// This class provides the implementation for an operation result whose index
/// can be represented "inline" in the underlying ValueImpl.
struct InlineOpResult : public OpResultImpl {
public:
  InlineOpResult(Type type, unsigned resultNo)
      : OpResultImpl(type, static_cast<ValueImpl::Kind>(resultNo)) {
    assert(resultNo < getMaxInlineResults());
  }
 
  /// Return the result number of this op result.
  unsigned getResultNumber() const { return static_cast<unsigned>(getKind()); }
 
  static bool classof(const OpResultImpl *value) {
    return value->getKind() != ValueImpl::Kind::OutOfLineOpResult;
  }
};
 
/// This class provides the implementation for an operation result whose index
/// cannot be represented "inline", and thus requires an additional index field.
class OutOfLineOpResult : public OpResultImpl {
public:
  OutOfLineOpResult(Type type, uint64_t outOfLineIndex)
      : OpResultImpl(type, Kind::OutOfLineOpResult),
        outOfLineIndex(outOfLineIndex) {}
 
  static bool classof(const OpResultImpl *value) {
    return value->getKind() == ValueImpl::Kind::OutOfLineOpResult;
  }
 
  /// Return the result number of this op result.
  unsigned getResultNumber() const {
    return outOfLineIndex + getMaxInlineResults();
  }
 
  /// The trailing result number, or the offset from the beginning of the
  /// `OutOfLineOpResult` array.
  uint64_t outOfLineIndex;
};
 
/// Return the result number of this op result.
inline unsigned OpResultImpl::getResultNumber() const {
  if (const auto *outOfLineResult = dyn_cast<OutOfLineOpResult>(this))
    return outOfLineResult->getResultNumber();
  return cast<InlineOpResult>(this)->getResultNumber();
}
 
/// TypedValue is a Value with a statically know type.
/// TypedValue can be null/empty
template <typename Ty>
struct TypedValue : Value {
  using Value::Value;
  using ValueType = Ty;
 
  static bool classof(Value value) { return llvm::isa<Ty>(value.getType()); }
 
  /// TypedValue<B> can implicitly convert to TypedValue<A> if B is assignable
  /// to A.
  template <typename ToTy,
            typename = typename std::enable_if<std::is_assignable<
                typename ToTy::ValueType &, Ty>::value>::type>
  operator ToTy() const {
    return llvm::cast<ToTy>(*this);
  }
 
  /// Return the known Type
  Ty getType() const { return llvm::cast<Ty>(Value::getType()); }
  void setType(Ty ty) { Value::setType(ty); }
};
 
} // namespace detail
 
/// This is a value defined by a result of an operation.
class OpResult : public Value {
public:
  using Value::Value;
 
  static bool classof(Value value) {
    return llvm::isa<detail::OpResultImpl>(value.getImpl());
  }
 
  /// Returns the operation that owns this result.
  Operation *getOwner() const { return getImpl()->getOwner(); }
 
  /// Returns the number of this result.
  unsigned getResultNumber() const { return getImpl()->getResultNumber(); }
 
private:
  /// Get a raw pointer to the internal implementation.
  detail::OpResultImpl *getImpl() const {
    return reinterpret_cast<detail::OpResultImpl *>(impl);
  }
 
  /// Given a number of operation results, returns the number that need to be
  /// stored inline.
  static unsigned getNumInline(unsigned numResults);
 
  /// Given a number of operation results, returns the number that need to be
  /// stored as trailing.
  static unsigned getNumTrailing(unsigned numResults);
 
  /// Allow access to constructor.
  friend Operation;
};
 
/// Make Value hashable.
inline ::llvm::hash_code hash_value(Value arg) {
  return ::llvm::hash_value(arg.getImpl());
}
 
template <typename Ty, typename Value = mlir::Value>
/// If Ty is mlir::Type this will select `Value` instead of having a wrapper
/// around it. This helps resolve ambiguous conversion issues.
using TypedValue = std::conditional_t<std::is_same_v<Ty, mlir::Type>,
                                      mlir::Value, detail::TypedValue<Ty>>;
 
} // namespace mlir
 
namespace llvm {
 
template <>
struct DenseMapInfo<mlir::Value> {
  static mlir::Value getEmptyKey() {
    void *pointer = llvm::DenseMapInfo<void *>::getEmptyKey();
    return mlir::Value::getFromOpaquePointer(pointer);
  }
  static mlir::Value getTombstoneKey() {
    void *pointer = llvm::DenseMapInfo<void *>::getTombstoneKey();
    return mlir::Value::getFromOpaquePointer(pointer);
  }
  static unsigned getHashValue(mlir::Value val) {
    return mlir::hash_value(val);
  }
  static bool isEqual(mlir::Value lhs, mlir::Value rhs) { return lhs == rhs; }
};
template <>
struct DenseMapInfo<mlir::BlockArgument> : public DenseMapInfo<mlir::Value> {
  static mlir::BlockArgument getEmptyKey() {
    void *pointer = llvm::DenseMapInfo<void *>::getEmptyKey();
    return reinterpret_cast<mlir::detail::BlockArgumentImpl *>(pointer);
  }
  static mlir::BlockArgument getTombstoneKey() {
    void *pointer = llvm::DenseMapInfo<void *>::getTombstoneKey();
    return reinterpret_cast<mlir::detail::BlockArgumentImpl *>(pointer);
  }
};
template <>
struct DenseMapInfo<mlir::OpResult> : public DenseMapInfo<mlir::Value> {
  static mlir::OpResult getEmptyKey() {
    void *pointer = llvm::DenseMapInfo<void *>::getEmptyKey();
    return reinterpret_cast<mlir::detail::OpResultImpl *>(pointer);
  }
  static mlir::OpResult getTombstoneKey() {
    void *pointer = llvm::DenseMapInfo<void *>::getTombstoneKey();
    return reinterpret_cast<mlir::detail::OpResultImpl *>(pointer);
  }
};
template <typename T>
struct DenseMapInfo<mlir::detail::TypedValue<T>>
    : public DenseMapInfo<mlir::Value> {
  static mlir::detail::TypedValue<T> getEmptyKey() {
    void *pointer = llvm::DenseMapInfo<void *>::getEmptyKey();
    return reinterpret_cast<mlir::detail::ValueImpl *>(pointer);
  }
  static mlir::detail::TypedValue<T> getTombstoneKey() {
    void *pointer = llvm::DenseMapInfo<void *>::getTombstoneKey();
    return reinterpret_cast<mlir::detail::ValueImpl *>(pointer);
  }
};
 
/// Allow stealing the low bits of a value.
template <>
struct PointerLikeTypeTraits<mlir::Value> {
public:
  static inline void *getAsVoidPointer(mlir::Value value) {
    return const_cast<void *>(value.getAsOpaquePointer());
  }
  static inline mlir::Value getFromVoidPointer(void *pointer) {
    return mlir::Value::getFromOpaquePointer(pointer);
  }
  enum {
    NumLowBitsAvailable =
        PointerLikeTypeTraits<mlir::detail::ValueImpl *>::NumLowBitsAvailable
  };
};
template <>
struct PointerLikeTypeTraits<mlir::BlockArgument>
    : public PointerLikeTypeTraits<mlir::Value> {
public:
  static inline mlir::BlockArgument getFromVoidPointer(void *pointer) {
    return reinterpret_cast<mlir::detail::BlockArgumentImpl *>(pointer);
  }
};
template <>
struct PointerLikeTypeTraits<mlir::OpResult>
    : public PointerLikeTypeTraits<mlir::Value> {
public:
  static inline mlir::OpResult getFromVoidPointer(void *pointer) {
    return reinterpret_cast<mlir::detail::OpResultImpl *>(pointer);
  }
};
template <typename T>
struct PointerLikeTypeTraits<mlir::detail::TypedValue<T>>
    : public PointerLikeTypeTraits<mlir::Value> {
public:
  static inline mlir::detail::TypedValue<T> getFromVoidPointer(void *pointer) {
    return reinterpret_cast<mlir::detail::ValueImpl *>(pointer);
  }
};
 
/// Add support for llvm style casts. We provide a cast between To and From if
/// From is mlir::Value or derives from it.
template <typename To, typename From>
struct CastInfo<
    To, From,
    std::enable_if_t<std::is_same_v<mlir::Value, std::remove_const_t<From>> ||
                     std::is_base_of_v<mlir::Value, From>>>
    : NullableValueCastFailed<To>,
      DefaultDoCastIfPossible<To, From, CastInfo<To, From>> {
  /// Arguments are taken as mlir::Value here and not as `From`, because
  /// when casting from an intermediate type of the hierarchy to one of its
  /// children, the val.getKind() inside T::classof will use the static
  /// getKind() of the parent instead of the non-static ValueImpl::getKind()
  /// that returns the dynamic type. This means that T::classof would end up
  /// comparing the static Kind of the children to the static Kind of its
  /// parent, making it impossible to downcast from the parent to the child.
  static inline bool isPossible(mlir::Value ty) {
    /// Return a constant true instead of a dynamic true when casting to self or
    /// up the hierarchy.
    if constexpr (std::is_base_of_v<To, From>) {
      return true;
    } else {
      return To::classof(ty);
    }
  }
  static inline To doCast(mlir::Value value) { return To(value.getImpl()); }
};
 
} // namespace llvm
 
#endif