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eb6c8f53b4
For now the allocator still uses the old (internal) construction mechanism by default. This will be phased out soon assuming no issues with the builder system come up. To invoke the new construction mechanism just pass '-regalloc=pbqp -pbqp-builder' to llc. To provide custom constraints a Target just needs to extend PBQPBuilder and pass an instance of their derived builder to the RegAllocPBQP constructor. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114272 91177308-0d34-0410-b5e6-96231b3b80d8
261 lines
9.2 KiB
C++
261 lines
9.2 KiB
C++
//===-- RegAllocPBQP.h ------------------------------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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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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//===----------------------------------------------------------------------===//
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//
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// This file defines the PBQPBuilder interface, for classes which build PBQP
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// instances to represent register allocation problems, and the RegAllocPBQP
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// interface.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_REGALLOCPBQP_H
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#define LLVM_CODEGEN_REGALLOCPBQP_H
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/PBQP/Graph.h"
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#include "llvm/CodeGen/PBQP/Solution.h"
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#include <map>
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namespace llvm {
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class LiveInterval;
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class MachineFunction;
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/// This class wraps up a PBQP instance representing a register allocation
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/// problem, plus the structures necessary to map back from the PBQP solution
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/// to a register allocation solution. (i.e. The PBQP-node <--> vreg map,
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/// and the PBQP option <--> storage location map).
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class PBQPRAProblem {
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public:
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typedef SmallVector<unsigned, 16> AllowedSet;
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PBQP::Graph& getGraph() { return graph; }
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const PBQP::Graph& getGraph() const { return graph; }
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/// Record the mapping between the given virtual register and PBQP node,
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/// and the set of allowed pregs for the vreg.
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///
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/// If you are extending
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/// PBQPBuilder you are unlikely to need this: Nodes and options for all
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/// vregs will already have been set up for you by the base class.
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template <typename AllowedRegsItr>
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void recordVReg(unsigned vreg, PBQP::Graph::NodeItr node,
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AllowedRegsItr arBegin, AllowedRegsItr arEnd) {
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assert(node2VReg.find(node) == node2VReg.end() && "Re-mapping node.");
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assert(vreg2Node.find(vreg) == vreg2Node.end() && "Re-mapping vreg.");
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assert(allowedSets[vreg].empty() && "vreg already has pregs.");
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node2VReg[node] = vreg;
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vreg2Node[vreg] = node;
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std::copy(arBegin, arEnd, std::back_inserter(allowedSets[vreg]));
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}
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/// Get the virtual register corresponding to the given PBQP node.
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unsigned getVRegForNode(PBQP::Graph::ConstNodeItr node) const;
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/// Get the PBQP node corresponding to the given virtual register.
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PBQP::Graph::NodeItr getNodeForVReg(unsigned vreg) const;
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/// Returns true if the given PBQP option represents a physical register,
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/// false otherwise.
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bool isPRegOption(unsigned vreg, unsigned option) const {
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// At present we only have spills or pregs, so anything that's not a
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// spill is a preg. (This might be extended one day to support remat).
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return !isSpillOption(vreg, option);
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}
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/// Returns true if the given PBQP option represents spilling, false
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/// otherwise.
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bool isSpillOption(unsigned vreg, unsigned option) const {
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// We hardcode option zero as the spill option.
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return option == 0;
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}
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/// Returns the allowed set for the given virtual register.
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const AllowedSet& getAllowedSet(unsigned vreg) const;
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/// Get PReg for option.
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unsigned getPRegForOption(unsigned vreg, unsigned option) const;
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private:
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typedef std::map<PBQP::Graph::ConstNodeItr, unsigned,
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PBQP::NodeItrComparator> Node2VReg;
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typedef DenseMap<unsigned, PBQP::Graph::NodeItr> VReg2Node;
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typedef std::map<unsigned, AllowedSet> AllowedSetMap;
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PBQP::Graph graph;
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Node2VReg node2VReg;
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VReg2Node vreg2Node;
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AllowedSetMap allowedSets;
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};
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/// Builds PBQP instances to represent register allocation problems. Includes
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/// spill, interference and coalescing costs by default. You can extend this
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/// class to support additional constraints for your architecture.
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class PBQPBuilder {
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private:
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PBQPBuilder(const PBQPBuilder&) {}
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void operator=(const PBQPBuilder&) {}
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public:
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typedef std::set<unsigned> RegSet;
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/// Default constructor.
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PBQPBuilder() {}
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/// Clean up a PBQPBuilder.
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virtual ~PBQPBuilder() {}
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/// Build a PBQP instance to represent the register allocation problem for
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/// the given MachineFunction.
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virtual std::auto_ptr<PBQPRAProblem> build(
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MachineFunction *mf,
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const LiveIntervals *lis,
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const RegSet &vregs);
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private:
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void addSpillCosts(PBQP::Vector &costVec, PBQP::PBQPNum spillCost);
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void addInterferenceCosts(PBQP::Matrix &costMat,
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const PBQPRAProblem::AllowedSet &vr1Allowed,
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const PBQPRAProblem::AllowedSet &vr2Allowed,
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const TargetRegisterInfo *tri);
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};
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///
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/// PBQP based allocators solve the register allocation problem by mapping
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/// register allocation problems to Partitioned Boolean Quadratic
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/// Programming problems.
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class RegAllocPBQP : public MachineFunctionPass {
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public:
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static char ID;
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/// Construct a PBQP register allocator.
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RegAllocPBQP(std::auto_ptr<PBQPBuilder> b) : MachineFunctionPass(ID), builder(b) {}
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/// Return the pass name.
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virtual const char* getPassName() const {
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return "PBQP Register Allocator";
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}
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/// PBQP analysis usage.
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virtual void getAnalysisUsage(AnalysisUsage &au) const;
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/// Perform register allocation
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virtual bool runOnMachineFunction(MachineFunction &MF);
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private:
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typedef std::map<const LiveInterval*, unsigned> LI2NodeMap;
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typedef std::vector<const LiveInterval*> Node2LIMap;
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typedef std::vector<unsigned> AllowedSet;
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typedef std::vector<AllowedSet> AllowedSetMap;
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typedef std::pair<unsigned, unsigned> RegPair;
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typedef std::map<RegPair, PBQP::PBQPNum> CoalesceMap;
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typedef std::vector<PBQP::Graph::NodeItr> NodeVector;
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typedef std::set<unsigned> RegSet;
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std::auto_ptr<PBQPBuilder> builder;
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MachineFunction *mf;
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const TargetMachine *tm;
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const TargetRegisterInfo *tri;
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const TargetInstrInfo *tii;
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const MachineLoopInfo *loopInfo;
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MachineRegisterInfo *mri;
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RenderMachineFunction *rmf;
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LiveIntervals *lis;
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LiveStacks *lss;
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VirtRegMap *vrm;
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LI2NodeMap li2Node;
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Node2LIMap node2LI;
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AllowedSetMap allowedSets;
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RegSet vregsToAlloc, emptyIntervalVRegs;
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NodeVector problemNodes;
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/// Builds a PBQP cost vector.
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template <typename RegContainer>
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PBQP::Vector buildCostVector(unsigned vReg,
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const RegContainer &allowed,
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const CoalesceMap &cealesces,
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PBQP::PBQPNum spillCost) const;
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/// \brief Builds a PBQP interference matrix.
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///
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/// @return Either a pointer to a non-zero PBQP matrix representing the
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/// allocation option costs, or a null pointer for a zero matrix.
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///
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/// Expects allowed sets for two interfering LiveIntervals. These allowed
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/// sets should contain only allocable registers from the LiveInterval's
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/// register class, with any interfering pre-colored registers removed.
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template <typename RegContainer>
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PBQP::Matrix* buildInterferenceMatrix(const RegContainer &allowed1,
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const RegContainer &allowed2) const;
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///
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/// Expects allowed sets for two potentially coalescable LiveIntervals,
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/// and an estimated benefit due to coalescing. The allowed sets should
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/// contain only allocable registers from the LiveInterval's register
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/// classes, with any interfering pre-colored registers removed.
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template <typename RegContainer>
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PBQP::Matrix* buildCoalescingMatrix(const RegContainer &allowed1,
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const RegContainer &allowed2,
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PBQP::PBQPNum cBenefit) const;
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/// \brief Finds coalescing opportunities and returns them as a map.
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///
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/// Any entries in the map are guaranteed coalescable, even if their
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/// corresponding live intervals overlap.
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CoalesceMap findCoalesces();
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/// \brief Finds the initial set of vreg intervals to allocate.
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void findVRegIntervalsToAlloc();
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/// \brief Constructs a PBQP problem representation of the register
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/// allocation problem for this function.
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///
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/// @return a PBQP solver object for the register allocation problem.
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PBQP::Graph constructPBQPProblem();
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/// \brief Adds a stack interval if the given live interval has been
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/// spilled. Used to support stack slot coloring.
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void addStackInterval(const LiveInterval *spilled,MachineRegisterInfo* mri);
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/// \brief Given a solved PBQP problem maps this solution back to a register
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/// assignment.
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bool mapPBQPToRegAlloc(const PBQP::Solution &solution);
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/// \brief Given a solved PBQP problem maps this solution back to a register
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/// assignment.
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bool mapPBQPToRegAlloc2(const PBQPRAProblem &problem,
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const PBQP::Solution &solution);
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/// \brief Postprocessing before final spilling. Sets basic block "live in"
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/// variables.
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void finalizeAlloc() const;
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};
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}
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#endif /* LLVM_CODEGEN_REGALLOCPBQP_H */
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