1 //===-- RegAllocPBQP.h ------------------------------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the PBQPBuilder interface, for classes which build PBQP
11 // instances to represent register allocation problems, and the RegAllocPBQP
14 //===----------------------------------------------------------------------===//
16 #ifndef LLVM_CODEGEN_REGALLOCPBQP_H
17 #define LLVM_CODEGEN_REGALLOCPBQP_H
19 #include "llvm/ADT/DenseMap.h"
20 #include "llvm/CodeGen/MachineFunctionPass.h"
21 #include "llvm/CodeGen/PBQP/Graph.h"
22 #include "llvm/CodeGen/PBQP/Solution.h"
29 class MachineFunction;
30 class MachineLoopInfo;
32 /// This class wraps up a PBQP instance representing a register allocation
33 /// problem, plus the structures necessary to map back from the PBQP solution
34 /// to a register allocation solution. (i.e. The PBQP-node <--> vreg map,
35 /// and the PBQP option <--> storage location map).
40 typedef SmallVector<unsigned, 16> AllowedSet;
42 PBQP::Graph& getGraph() { return graph; }
44 const PBQP::Graph& getGraph() const { return graph; }
46 /// Record the mapping between the given virtual register and PBQP node,
47 /// and the set of allowed pregs for the vreg.
49 /// If you are extending
50 /// PBQPBuilder you are unlikely to need this: Nodes and options for all
51 /// vregs will already have been set up for you by the base class.
52 template <typename AllowedRegsItr>
53 void recordVReg(unsigned vreg, PBQP::Graph::NodeItr node,
54 AllowedRegsItr arBegin, AllowedRegsItr arEnd) {
55 assert(node2VReg.find(node) == node2VReg.end() && "Re-mapping node.");
56 assert(vreg2Node.find(vreg) == vreg2Node.end() && "Re-mapping vreg.");
57 assert(allowedSets[vreg].empty() && "vreg already has pregs.");
59 node2VReg[node] = vreg;
60 vreg2Node[vreg] = node;
61 std::copy(arBegin, arEnd, std::back_inserter(allowedSets[vreg]));
64 /// Get the virtual register corresponding to the given PBQP node.
65 unsigned getVRegForNode(PBQP::Graph::ConstNodeItr node) const;
67 /// Get the PBQP node corresponding to the given virtual register.
68 PBQP::Graph::NodeItr getNodeForVReg(unsigned vreg) const;
70 /// Returns true if the given PBQP option represents a physical register,
72 bool isPRegOption(unsigned vreg, unsigned option) const {
73 // At present we only have spills or pregs, so anything that's not a
74 // spill is a preg. (This might be extended one day to support remat).
75 return !isSpillOption(vreg, option);
78 /// Returns true if the given PBQP option represents spilling, false
80 bool isSpillOption(unsigned vreg, unsigned option) const {
81 // We hardcode option zero as the spill option.
85 /// Returns the allowed set for the given virtual register.
86 const AllowedSet& getAllowedSet(unsigned vreg) const;
88 /// Get PReg for option.
89 unsigned getPRegForOption(unsigned vreg, unsigned option) const;
93 typedef std::map<PBQP::Graph::ConstNodeItr, unsigned,
94 PBQP::NodeItrComparator> Node2VReg;
95 typedef DenseMap<unsigned, PBQP::Graph::NodeItr> VReg2Node;
96 typedef std::map<unsigned, AllowedSet> AllowedSetMap;
102 AllowedSetMap allowedSets;
106 /// Builds PBQP instances to represent register allocation problems. Includes
107 /// spill, interference and coalescing costs by default. You can extend this
108 /// class to support additional constraints for your architecture.
111 PBQPBuilder(const PBQPBuilder&) {}
112 void operator=(const PBQPBuilder&) {}
115 typedef std::set<unsigned> RegSet;
117 /// Default constructor.
120 /// Clean up a PBQPBuilder.
121 virtual ~PBQPBuilder() {}
123 /// Build a PBQP instance to represent the register allocation problem for
124 /// the given MachineFunction.
125 virtual std::auto_ptr<PBQPRAProblem> build(
127 const LiveIntervals *lis,
128 const MachineLoopInfo *loopInfo,
129 const RegSet &vregs);
132 void addSpillCosts(PBQP::Vector &costVec, PBQP::PBQPNum spillCost);
134 void addInterferenceCosts(PBQP::Matrix &costMat,
135 const PBQPRAProblem::AllowedSet &vr1Allowed,
136 const PBQPRAProblem::AllowedSet &vr2Allowed,
137 const TargetRegisterInfo *tri);
140 /// Extended builder which adds coalescing constraints to a problem.
141 class PBQPBuilderWithCoalescing : public PBQPBuilder {
144 /// Build a PBQP instance to represent the register allocation problem for
145 /// the given MachineFunction.
146 virtual std::auto_ptr<PBQPRAProblem> build(
148 const LiveIntervals *lis,
149 const MachineLoopInfo *loopInfo,
150 const RegSet &vregs);
154 void addPhysRegCoalesce(PBQP::Vector &costVec, unsigned pregOption,
155 PBQP::PBQPNum benefit);
157 void addVirtRegCoalesce(PBQP::Matrix &costMat,
158 const PBQPRAProblem::AllowedSet &vr1Allowed,
159 const PBQPRAProblem::AllowedSet &vr2Allowed,
160 PBQP::PBQPNum benefit);
164 /// PBQP based allocators solve the register allocation problem by mapping
165 /// register allocation problems to Partitioned Boolean Quadratic
166 /// Programming problems.
167 class RegAllocPBQP : public MachineFunctionPass {
172 /// Construct a PBQP register allocator.
173 RegAllocPBQP(std::auto_ptr<PBQPBuilder> b) : MachineFunctionPass(ID), builder(b) {}
175 /// Return the pass name.
176 virtual const char* getPassName() const {
177 return "PBQP Register Allocator";
180 /// PBQP analysis usage.
181 virtual void getAnalysisUsage(AnalysisUsage &au) const;
183 /// Perform register allocation
184 virtual bool runOnMachineFunction(MachineFunction &MF);
188 typedef std::map<const LiveInterval*, unsigned> LI2NodeMap;
189 typedef std::vector<const LiveInterval*> Node2LIMap;
190 typedef std::vector<unsigned> AllowedSet;
191 typedef std::vector<AllowedSet> AllowedSetMap;
192 typedef std::pair<unsigned, unsigned> RegPair;
193 typedef std::map<RegPair, PBQP::PBQPNum> CoalesceMap;
194 typedef std::vector<PBQP::Graph::NodeItr> NodeVector;
195 typedef std::set<unsigned> RegSet;
198 std::auto_ptr<PBQPBuilder> builder;
201 const TargetMachine *tm;
202 const TargetRegisterInfo *tri;
203 const TargetInstrInfo *tii;
204 const MachineLoopInfo *loopInfo;
205 MachineRegisterInfo *mri;
206 RenderMachineFunction *rmf;
214 AllowedSetMap allowedSets;
215 RegSet vregsToAlloc, emptyIntervalVRegs;
216 NodeVector problemNodes;
219 /// Builds a PBQP cost vector.
220 template <typename RegContainer>
221 PBQP::Vector buildCostVector(unsigned vReg,
222 const RegContainer &allowed,
223 const CoalesceMap &cealesces,
224 PBQP::PBQPNum spillCost) const;
226 /// \brief Builds a PBQP interference matrix.
228 /// @return Either a pointer to a non-zero PBQP matrix representing the
229 /// allocation option costs, or a null pointer for a zero matrix.
231 /// Expects allowed sets for two interfering LiveIntervals. These allowed
232 /// sets should contain only allocable registers from the LiveInterval's
233 /// register class, with any interfering pre-colored registers removed.
234 template <typename RegContainer>
235 PBQP::Matrix* buildInterferenceMatrix(const RegContainer &allowed1,
236 const RegContainer &allowed2) const;
239 /// Expects allowed sets for two potentially coalescable LiveIntervals,
240 /// and an estimated benefit due to coalescing. The allowed sets should
241 /// contain only allocable registers from the LiveInterval's register
242 /// classes, with any interfering pre-colored registers removed.
243 template <typename RegContainer>
244 PBQP::Matrix* buildCoalescingMatrix(const RegContainer &allowed1,
245 const RegContainer &allowed2,
246 PBQP::PBQPNum cBenefit) const;
248 /// \brief Finds coalescing opportunities and returns them as a map.
250 /// Any entries in the map are guaranteed coalescable, even if their
251 /// corresponding live intervals overlap.
252 CoalesceMap findCoalesces();
254 /// \brief Finds the initial set of vreg intervals to allocate.
255 void findVRegIntervalsToAlloc();
257 /// \brief Constructs a PBQP problem representation of the register
258 /// allocation problem for this function.
260 /// @return a PBQP solver object for the register allocation problem.
261 PBQP::Graph constructPBQPProblem();
263 /// \brief Adds a stack interval if the given live interval has been
264 /// spilled. Used to support stack slot coloring.
265 void addStackInterval(const LiveInterval *spilled,MachineRegisterInfo* mri);
267 /// \brief Given a solved PBQP problem maps this solution back to a register
269 bool mapPBQPToRegAlloc(const PBQP::Solution &solution);
271 /// \brief Given a solved PBQP problem maps this solution back to a register
273 bool mapPBQPToRegAlloc2(const PBQPRAProblem &problem,
274 const PBQP::Solution &solution);
276 /// \brief Postprocessing before final spilling. Sets basic block "live in"
278 void finalizeAlloc() const;
284 #endif /* LLVM_CODEGEN_REGALLOCPBQP_H */