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//===-- CodeGen/MachineConstantPool.h - Abstract Constant Pool --*- C++ -*-===//
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// The LLVM Compiler Infrastructure
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//===----------------------------------------------------------------------===//
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/// This file declares the MachineConstantPool class which is an abstract
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/// constant pool to keep track of constants referenced by a function.
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_MACHINECONSTANTPOOL_H
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#define LLVM_CODEGEN_MACHINECONSTANTPOOL_H
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#include "llvm/ADT/DenseSet.h"
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class FoldingSetNodeID;
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class MachineConstantPool;
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/// Abstract base class for all machine specific constantpool value subclasses.
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class MachineConstantPoolValue {
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virtual void anchor();
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explicit MachineConstantPoolValue(Type *ty) : Ty(ty) {}
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virtual ~MachineConstantPoolValue() {}
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/// getType - get type of this MachineConstantPoolValue.
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Type *getType() const { return Ty; }
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/// getRelocationInfo - This method classifies the entry according to
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/// whether or not it may generate a relocation entry. This must be
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/// conservative, so if it might codegen to a relocatable entry, it should say
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/// so. The return values are the same as Constant::getRelocationInfo().
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virtual unsigned getRelocationInfo() const = 0;
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virtual int getExistingMachineCPValue(MachineConstantPool *CP,
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unsigned Alignment) = 0;
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virtual void addSelectionDAGCSEId(FoldingSetNodeID &ID) = 0;
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/// print - Implement operator<<
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virtual void print(raw_ostream &O) const = 0;
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inline raw_ostream &operator<<(raw_ostream &OS,
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const MachineConstantPoolValue &V) {
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/// This class is a data container for one entry in a MachineConstantPool.
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/// It contains a pointer to the value and an offset from the start of
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/// the constant pool.
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/// @brief An entry in a MachineConstantPool
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class MachineConstantPoolEntry {
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/// The constant itself.
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const Constant *ConstVal;
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MachineConstantPoolValue *MachineCPVal;
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/// The required alignment for this entry. The top bit is set when Val is
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/// a target specific MachineConstantPoolValue.
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MachineConstantPoolEntry(const Constant *V, unsigned A)
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MachineConstantPoolEntry(MachineConstantPoolValue *V, unsigned A)
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Alignment |= 1U << (sizeof(unsigned)*CHAR_BIT-1);
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/// isMachineConstantPoolEntry - Return true if the MachineConstantPoolEntry
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/// is indeed a target specific constantpool entry, not a wrapper over a
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bool isMachineConstantPoolEntry() const {
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return (int)Alignment < 0;
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int getAlignment() const {
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return Alignment & ~(1 << (sizeof(unsigned)*CHAR_BIT-1));
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Type *getType() const;
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/// getRelocationInfo - This method classifies the entry according to
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/// whether or not it may generate a relocation entry. This must be
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/// conservative, so if it might codegen to a relocatable entry, it should say
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/// so. The return values are:
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/// 0: This constant pool entry is guaranteed to never have a relocation
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/// applied to it (because it holds a simple constant like '4').
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/// 1: This entry has relocations, but the entries are guaranteed to be
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/// resolvable by the static linker, so the dynamic linker will never see
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/// 2: This entry may have arbitrary relocations.
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unsigned getRelocationInfo() const;
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/// The MachineConstantPool class keeps track of constants referenced by a
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/// function which must be spilled to memory. This is used for constants which
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/// are unable to be used directly as operands to instructions, which typically
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/// include floating point and large integer constants.
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/// Instructions reference the address of these constant pool constants through
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/// the use of MO_ConstantPoolIndex values. When emitting assembly or machine
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/// code, these virtual address references are converted to refer to the
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/// address of the function constant pool values.
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/// @brief The machine constant pool.
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class MachineConstantPool {
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const TargetData *TD; ///< The machine's TargetData.
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unsigned PoolAlignment; ///< The alignment for the pool.
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std::vector<MachineConstantPoolEntry> Constants; ///< The pool of constants.
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/// MachineConstantPoolValues that use an existing MachineConstantPoolEntry.
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DenseSet<MachineConstantPoolValue*> MachineCPVsSharingEntries;
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/// @brief The only constructor.
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explicit MachineConstantPool(const TargetData *td)
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: TD(td), PoolAlignment(1) {}
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~MachineConstantPool();
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/// getConstantPoolAlignment - Return the alignment required by
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/// the whole constant pool, of which the first element must be aligned.
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unsigned getConstantPoolAlignment() const { return PoolAlignment; }
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/// getConstantPoolIndex - Create a new entry in the constant pool or return
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/// an existing one. User must specify the minimum required alignment for
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unsigned getConstantPoolIndex(const Constant *C, unsigned Alignment);
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unsigned getConstantPoolIndex(MachineConstantPoolValue *V,unsigned Alignment);
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/// isEmpty - Return true if this constant pool contains no constants.
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bool isEmpty() const { return Constants.empty(); }
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const std::vector<MachineConstantPoolEntry> &getConstants() const {
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/// print - Used by the MachineFunction printer to print information about
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/// constant pool objects. Implemented in MachineFunction.cpp
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void print(raw_ostream &OS) const;
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/// dump - Call print(cerr) to be called from the debugger.
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} // End llvm namespace