1 //===-- RegAllocBase.h - basic regalloc interface and driver --*- C++ -*---===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file defines the RegAllocBase class, which is the skeleton of a basic 11 // register allocation algorithm and interface for extending it. It provides the 12 // building blocks on which to construct other experimental allocators and test 13 // the validity of two principles: 14 // 15 // - If virtual and physical register liveness is modeled using intervals, then 16 // on-the-fly interference checking is cheap. Furthermore, interferences can be 17 // lazily cached and reused. 18 // 19 // - Register allocation complexity, and generated code performance is 20 // determined by the effectiveness of live range splitting rather than optimal 21 // coloring. 22 // 23 // Following the first principle, interfering checking revolves around the 24 // LiveIntervalUnion data structure. 25 // 26 // To fulfill the second principle, the basic allocator provides a driver for 27 // incremental splitting. It essentially punts on the problem of register 28 // coloring, instead driving the assignment of virtual to physical registers by 29 // the cost of splitting. The basic allocator allows for heuristic reassignment 30 // of registers, if a more sophisticated allocator chooses to do that. 31 // 32 // This framework provides a way to engineer the compile time vs. code 33 // quality trade-off without relying on a particular theoretical solver. 34 // 35 //===----------------------------------------------------------------------===// 36 37 #ifndef LLVM_CODEGEN_REGALLOCBASE 38 #define LLVM_CODEGEN_REGALLOCBASE 39 40 #include "LiveIntervalUnion.h" 41 #include "llvm/CodeGen/RegisterClassInfo.h" 42 #include "llvm/ADT/OwningPtr.h" 43 44 namespace llvm { 45 46 template<typename T> class SmallVectorImpl; 47 class TargetRegisterInfo; 48 class VirtRegMap; 49 class LiveIntervals; 50 class LiveRegMatrix; 51 class Spiller; 52 53 /// RegAllocBase provides the register allocation driver and interface that can 54 /// be extended to add interesting heuristics. 55 /// 56 /// Register allocators must override the selectOrSplit() method to implement 57 /// live range splitting. They must also override enqueue/dequeue to provide an 58 /// assignment order. 59 class RegAllocBase { 60 protected: 61 const TargetRegisterInfo *TRI; 62 MachineRegisterInfo *MRI; 63 VirtRegMap *VRM; 64 LiveIntervals *LIS; 65 LiveRegMatrix *Matrix; 66 RegisterClassInfo RegClassInfo; 67 68 RegAllocBase(): TRI(0), MRI(0), VRM(0), LIS(0), Matrix(0) {} 69 70 virtual ~RegAllocBase() {} 71 72 // A RegAlloc pass should call this before allocatePhysRegs. 73 void init(VirtRegMap &vrm, LiveIntervals &lis, LiveRegMatrix &mat); 74 75 // The top-level driver. The output is a VirtRegMap that us updated with 76 // physical register assignments. 77 void allocatePhysRegs(); 78 79 // Get a temporary reference to a Spiller instance. 80 virtual Spiller &spiller() = 0; 81 82 /// enqueue - Add VirtReg to the priority queue of unassigned registers. 83 virtual void enqueue(LiveInterval *LI) = 0; 84 85 /// dequeue - Return the next unassigned register, or NULL. 86 virtual LiveInterval *dequeue() = 0; 87 88 // A RegAlloc pass should override this to provide the allocation heuristics. 89 // Each call must guarantee forward progess by returning an available PhysReg 90 // or new set of split live virtual registers. It is up to the splitter to 91 // converge quickly toward fully spilled live ranges. 92 virtual unsigned selectOrSplit(LiveInterval &VirtReg, 93 SmallVectorImpl<LiveInterval*> &splitLVRs) = 0; 94 95 // Use this group name for NamedRegionTimer. 96 static const char *TimerGroupName; 97 98 public: 99 /// VerifyEnabled - True when -verify-regalloc is given. 100 static bool VerifyEnabled; 101 102 private: 103 void seedLiveRegs(); 104 }; 105 106 } // end namespace llvm 107 108 #endif // !defined(LLVM_CODEGEN_REGALLOCBASE) 109
