src/cpu/o3/rename_map.hh - public/gem5 - Git at Google

 /*
  * Copyright (c) 2015-2017 ARM Limited
  * All rights reserved.
  *
  * The license below extends only to copyright in the software and shall
  * not be construed as granting a license to any other intellectual
  * property including but not limited to intellectual property relating
  * to a hardware implementation of the functionality of the software
  * licensed hereunder.  You may use the software subject to the license
  * terms below provided that you ensure that this notice is replicated
  * unmodified and in its entirety in all distributions of the software,
  * modified or unmodified, in source code or in binary form.
  *
  * Copyright (c) 2004-2005 The Regents of The University of Michigan
  * Copyright (c) 2013 Advanced Micro Devices, Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met: redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer;
  * redistributions in binary form must reproduce the above copyright
  * notice, this list of conditions and the following disclaimer in the
  * documentation and/or other materials provided with the distribution;
  * neither the name of the copyright holders nor the names of its
  * contributors may be used to endorse or promote products derived from
  * this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #ifndef __CPU_O3_RENAME_MAP_HH__
 #define __CPU_O3_RENAME_MAP_HH__

 #include <algorithm>
 #include <array>
 #include <iostream>
 #include <limits>
 #include <utility>
 #include <vector>

 #include "arch/generic/isa.hh"
 #include "cpu/o3/dyn_inst_ptr.hh"
 #include "cpu/o3/free_list.hh"
 #include "cpu/o3/regfile.hh"
 #include "cpu/reg_class.hh"

 namespace gem5
 {

 namespace o3
 {

 /**
  * Register rename map for a single class of registers (e.g., integer
  * or floating point).  Because the register class is implicitly
  * determined by the rename map instance being accessed, all
  * architectural register index parameters and values in this class
  * are relative (e.g., %fp2 is just index 2).
  */
 class SimpleRenameMap
 {
   private:
     using Arch2PhysMap = std::vector<PhysRegIdPtr>;
     /** The acutal arch-to-phys register map */
     Arch2PhysMap map;
   public:
     using iterator = Arch2PhysMap::iterator;
     using const_iterator = Arch2PhysMap::const_iterator;
   private:

     /**
      * Pointer to the free list from which new physical registers
      * should be allocated in rename()
      */
     SimpleFreeList *freeList;

   public:

     SimpleRenameMap();

     /**
      * Because we have an array of rename maps (one per thread) in the CPU,
      * it's awkward to initialize this object via the constructor.
      * Instead, this method is used for initialization.
      */
     void init(const RegClass &reg_class, SimpleFreeList *_freeList);

     /**
      * Pair of a physical register and a physical register.  Used to
      * return the physical register that a logical register has been
      * renamed to, and the previous physical register that the same
      * logical register was previously mapped to.
      */
     typedef std::pair<PhysRegIdPtr, PhysRegIdPtr> RenameInfo;

     /**
      * Tell rename map to get a new free physical register to remap
      * the specified architectural register.
      * @param arch_reg The architectural register to remap.
      * @return A RenameInfo pair indicating both the new and previous
      * physical registers.
      */
     RenameInfo rename(const RegId& arch_reg);

     /**
      * Look up the physical register mapped to an architectural register.
      * @param arch_reg The architectural register to look up.
      * @return The physical register it is currently mapped to.
      */
     PhysRegIdPtr
     lookup(const RegId& arch_reg) const
     {
         assert(arch_reg.index() <= map.size());
         return map[arch_reg.index()];
     }

     /**
      * Update rename map with a specific mapping.  Generally used to
      * roll back to old mappings on a squash.
      * @param arch_reg The architectural register to remap.
      * @param phys_reg The physical register to remap it to.
      */
     void
     setEntry(const RegId& arch_reg, PhysRegIdPtr phys_reg)
     {
         assert(arch_reg.index() <= map.size());
         map[arch_reg.index()] = phys_reg;
     }

     /** Return the number of free entries on the associated free list. */
     unsigned numFreeEntries() const { return freeList->numFreeRegs(); }

     size_t numArchRegs() const { return map.size(); }

     /** Forward begin/cbegin to the map. */
     /** @{ */
     iterator begin() { return map.begin(); }
     const_iterator begin() const { return map.begin(); }
     const_iterator cbegin() const { return map.cbegin(); }
     /** @} */

     /** Forward end/cend to the map. */
     /** @{ */
     iterator end() { return map.end(); }
     const_iterator end() const { return map.end(); }
     const_iterator cend() const { return map.cend(); }
     /** @} */
 };

 /**
  * Unified register rename map for all classes of registers.  Wraps a
  * set of class-specific rename maps.  Methods that do not specify a
  * register class (e.g., rename()) take register ids,
  * while methods that do specify a register class (e.g., renameInt())
  * take register indices.
  */
 class UnifiedRenameMap
 {
   private:
     std::array<SimpleRenameMap, CCRegClass + 1> renameMaps;

     static inline PhysRegId invalidPhysRegId{};

     /**
      * The register file object is used only to get PhysRegIdPtr
      * on MiscRegs, as they are stored in it.
      */
     PhysRegFile *regFile;

   public:

     typedef SimpleRenameMap::RenameInfo RenameInfo;

     /** Default constructor.  init() must be called prior to use. */
     UnifiedRenameMap() : regFile(nullptr) {};

     /** Destructor. */
     ~UnifiedRenameMap() {};

     /** Initializes rename map with given parameters. */
     void init(const BaseISA::RegClasses &regClasses,
               PhysRegFile *_regFile, UnifiedFreeList *freeList);

     /**
      * Tell rename map to get a new free physical register to remap
      * the specified architectural register. This version takes a
      * RegId and reads the  appropriate class-specific rename table.
      * @param arch_reg The architectural register id to remap.
      * @return A RenameInfo pair indicating both the new and previous
      * physical registers.
      */
     RenameInfo
     rename(const RegId& arch_reg)
     {
         if (!arch_reg.isRenameable()) {
             // misc regs aren't really renamed, just remapped
             PhysRegIdPtr phys_reg = lookup(arch_reg);
             // Set the new register to the previous one to keep the same
             // mapping throughout the execution.
             return RenameInfo(phys_reg, phys_reg);
         }

         return renameMaps[arch_reg.classValue()].rename(arch_reg);
     }

     /**
      * Look up the physical register mapped to an architectural register.
      * This version takes a flattened architectural register id
      * and calls the appropriate class-specific rename table.
      * @param arch_reg The architectural register to look up.
      * @return The physical register it is currently mapped to.
      */
     PhysRegIdPtr
     lookup(const RegId& arch_reg) const
     {
         auto reg_class = arch_reg.classValue();
         if (reg_class == InvalidRegClass) {
             return &invalidPhysRegId;
         } else if (reg_class == MiscRegClass) {
             // misc regs aren't really renamed, they keep the same
             // mapping throughout the execution.
             return regFile->getMiscRegId(arch_reg.index());
         }
         return renameMaps[reg_class].lookup(arch_reg);
     }

     /**
      * Update rename map with a specific mapping.  Generally used to
      * roll back to old mappings on a squash.  This version takes a
      * flattened architectural register id and calls the
      * appropriate class-specific rename table.
      * @param arch_reg The architectural register to remap.
      * @param phys_reg The physical register to remap it to.
      */
     void
     setEntry(const RegId& arch_reg, PhysRegIdPtr phys_reg)
     {
         assert(phys_reg->is(arch_reg.classValue()));
         if (!arch_reg.isRenameable()) {
             // Misc registers do not actually rename, so don't change
             // their mappings.  We end up here when a commit or squash
             // tries to update or undo a hardwired misc reg nmapping,
             // which should always be setting it to what it already is.
             assert(phys_reg == lookup(arch_reg));
             return;
         }

         return renameMaps[arch_reg.classValue()].setEntry(arch_reg, phys_reg);
     }

     /**
      * Return the minimum number of free entries across all of the
      * register classes.  The minimum is used so we guarantee that
      * this number of entries is available regardless of which class
      * of registers is requested.
      */
     unsigned
     numFreeEntries() const
     {
         auto min_free = std::numeric_limits<unsigned>::max();
         for (auto &map: renameMaps) {
             // If this map isn't empty (not used)...
             if (map.numArchRegs())
                 min_free = std::min(min_free, map.numFreeEntries());
         }
         return min_free;
     }

     unsigned
     numFreeEntries(RegClassType type) const
     {
         return renameMaps[type].numFreeEntries();
     }

     /**
      * Return whether there are enough registers to serve the request.
      */
     bool canRename(DynInstPtr inst) const;
 };

 } // namespace o3
 } // namespace gem5

 #endif //__CPU_O3_RENAME_MAP_HH__
	/*
	* Copyright (c) 2015-2017 ARM Limited
	* All rights reserved.
	*
	* The license below extends only to copyright in the software and shall
	* not be construed as granting a license to any other intellectual
	* property including but not limited to intellectual property relating
	* to a hardware implementation of the functionality of the software
	* licensed hereunder. You may use the software subject to the license
	* terms below provided that you ensure that this notice is replicated
	* unmodified and in its entirety in all distributions of the software,
	* modified or unmodified, in source code or in binary form.
	*
	* Copyright (c) 2004-2005 The Regents of The University of Michigan
	* Copyright (c) 2013 Advanced Micro Devices, Inc.
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions are
	* met: redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer;
	* redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution;
	* neither the name of the copyright holders nor the names of its
	* contributors may be used to endorse or promote products derived from
	* this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#ifndef __CPU_O3_RENAME_MAP_HH__
	#define __CPU_O3_RENAME_MAP_HH__

	#include <algorithm>
	#include <array>
	#include <iostream>
	#include <limits>
	#include <utility>
	#include <vector>

	#include "arch/generic/isa.hh"
	#include "cpu/o3/dyn_inst_ptr.hh"
	#include "cpu/o3/free_list.hh"
	#include "cpu/o3/regfile.hh"
	#include "cpu/reg_class.hh"

	namespace gem5
	{

	namespace o3
	{

	/**
	* Register rename map for a single class of registers (e.g., integer
	* or floating point). Because the register class is implicitly
	* determined by the rename map instance being accessed, all
	* architectural register index parameters and values in this class
	* are relative (e.g., %fp2 is just index 2).
	*/
	class SimpleRenameMap
	{
	private:
	using Arch2PhysMap = std::vector<PhysRegIdPtr>;
	/** The acutal arch-to-phys register map */
	Arch2PhysMap map;
	public:
	using iterator = Arch2PhysMap::iterator;
	using const_iterator = Arch2PhysMap::const_iterator;
	private:

	/**
	* Pointer to the free list from which new physical registers
	* should be allocated in rename()
	*/
	SimpleFreeList *freeList;

	public:

	SimpleRenameMap();

	/**
	* Because we have an array of rename maps (one per thread) in the CPU,
	* it's awkward to initialize this object via the constructor.
	* Instead, this method is used for initialization.
	*/
	void init(const RegClass &reg_class, SimpleFreeList *_freeList);

	/**
	* Pair of a physical register and a physical register. Used to
	* return the physical register that a logical register has been
	* renamed to, and the previous physical register that the same
	* logical register was previously mapped to.
	*/
	typedef std::pair<PhysRegIdPtr, PhysRegIdPtr> RenameInfo;

	/**
	* Tell rename map to get a new free physical register to remap
	* the specified architectural register.
	* @param arch_reg The architectural register to remap.
	* @return A RenameInfo pair indicating both the new and previous
	* physical registers.
	*/
	RenameInfo rename(const RegId& arch_reg);

	/**
	* Look up the physical register mapped to an architectural register.
	* @param arch_reg The architectural register to look up.
	* @return The physical register it is currently mapped to.
	*/
	PhysRegIdPtr
	lookup(const RegId& arch_reg) const
	{
	assert(arch_reg.index() <= map.size());
	return map[arch_reg.index()];
	}

	/**
	* Update rename map with a specific mapping. Generally used to
	* roll back to old mappings on a squash.
	* @param arch_reg The architectural register to remap.
	* @param phys_reg The physical register to remap it to.
	*/
	void
	setEntry(const RegId& arch_reg, PhysRegIdPtr phys_reg)
	{
	assert(arch_reg.index() <= map.size());
	map[arch_reg.index()] = phys_reg;
	}

	/** Return the number of free entries on the associated free list. */
	unsigned numFreeEntries() const { return freeList->numFreeRegs(); }

	size_t numArchRegs() const { return map.size(); }

	/** Forward begin/cbegin to the map. */
	/** @{ */
	iterator begin() { return map.begin(); }
	const_iterator begin() const { return map.begin(); }
	const_iterator cbegin() const { return map.cbegin(); }
	/** @} */

	/** Forward end/cend to the map. */
	/** @{ */
	iterator end() { return map.end(); }
	const_iterator end() const { return map.end(); }
	const_iterator cend() const { return map.cend(); }
	/** @} */
	};

	/**
	* Unified register rename map for all classes of registers. Wraps a
	* set of class-specific rename maps. Methods that do not specify a
	* register class (e.g., rename()) take register ids,
	* while methods that do specify a register class (e.g., renameInt())
	* take register indices.
	*/
	class UnifiedRenameMap
	{
	private:
	std::array<SimpleRenameMap, CCRegClass + 1> renameMaps;

	static inline PhysRegId invalidPhysRegId{};

	/**
	* The register file object is used only to get PhysRegIdPtr
	* on MiscRegs, as they are stored in it.
	*/
	PhysRegFile *regFile;

	public:

	typedef SimpleRenameMap::RenameInfo RenameInfo;

	/** Default constructor. init() must be called prior to use. */
	UnifiedRenameMap() : regFile(nullptr) {};

	/** Destructor. */
	~UnifiedRenameMap() {};

	/** Initializes rename map with given parameters. */
	void init(const BaseISA::RegClasses &regClasses,
	PhysRegFile _regFile, UnifiedFreeList freeList);

	/**
	* Tell rename map to get a new free physical register to remap
	* the specified architectural register. This version takes a
	* RegId and reads the appropriate class-specific rename table.
	* @param arch_reg The architectural register id to remap.
	* @return A RenameInfo pair indicating both the new and previous
	* physical registers.
	*/
	RenameInfo
	rename(const RegId& arch_reg)
	{
	if (!arch_reg.isRenameable()) {
	// misc regs aren't really renamed, just remapped
	PhysRegIdPtr phys_reg = lookup(arch_reg);
	// Set the new register to the previous one to keep the same
	// mapping throughout the execution.
	return RenameInfo(phys_reg, phys_reg);
	}

	return renameMaps[arch_reg.classValue()].rename(arch_reg);
	}

	/**
	* Look up the physical register mapped to an architectural register.
	* This version takes a flattened architectural register id
	* and calls the appropriate class-specific rename table.
	* @param arch_reg The architectural register to look up.
	* @return The physical register it is currently mapped to.
	*/
	PhysRegIdPtr
	lookup(const RegId& arch_reg) const
	{
	auto reg_class = arch_reg.classValue();
	if (reg_class == InvalidRegClass) {
	return &invalidPhysRegId;
	} else if (reg_class == MiscRegClass) {
	// misc regs aren't really renamed, they keep the same
	// mapping throughout the execution.
	return regFile->getMiscRegId(arch_reg.index());
	}
	return renameMaps[reg_class].lookup(arch_reg);
	}

	/**
	* Update rename map with a specific mapping. Generally used to
	* roll back to old mappings on a squash. This version takes a
	* flattened architectural register id and calls the
	* appropriate class-specific rename table.
	* @param arch_reg The architectural register to remap.
	* @param phys_reg The physical register to remap it to.
	*/
	void
	setEntry(const RegId& arch_reg, PhysRegIdPtr phys_reg)
	{
	assert(phys_reg->is(arch_reg.classValue()));
	if (!arch_reg.isRenameable()) {
	// Misc registers do not actually rename, so don't change
	// their mappings. We end up here when a commit or squash
	// tries to update or undo a hardwired misc reg nmapping,
	// which should always be setting it to what it already is.
	assert(phys_reg == lookup(arch_reg));
	return;
	}

	return renameMaps[arch_reg.classValue()].setEntry(arch_reg, phys_reg);
	}

	/**
	* Return the minimum number of free entries across all of the
	* register classes. The minimum is used so we guarantee that
	* this number of entries is available regardless of which class
	* of registers is requested.
	*/
	unsigned
	numFreeEntries() const
	{
	auto min_free = std::numeric_limits<unsigned>::max();
	for (auto &map: renameMaps) {
	// If this map isn't empty (not used)...
	if (map.numArchRegs())
	min_free = std::min(min_free, map.numFreeEntries());
	}
	return min_free;
	}

	unsigned
	numFreeEntries(RegClassType type) const
	{
	return renameMaps[type].numFreeEntries();
	}

	/**
	* Return whether there are enough registers to serve the request.
	*/
	bool canRename(DynInstPtr inst) const;
	};

	} // namespace o3
	} // namespace gem5

	#endif //__CPU_O3_RENAME_MAP_HH__