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109 lines
3.9 KiB
C++
109 lines
3.9 KiB
C++
//===-- RegAllocBase.h - basic regalloc interface and driver --*- 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 RegAllocBase class, which is the skeleton of a basic
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// register allocation algorithm and interface for extending it. It provides the
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// building blocks on which to construct other experimental allocators and test
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// the validity of two principles:
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//
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// - If virtual and physical register liveness is modeled using intervals, then
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// on-the-fly interference checking is cheap. Furthermore, interferences can be
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// lazily cached and reused.
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//
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// - Register allocation complexity, and generated code performance is
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// determined by the effectiveness of live range splitting rather than optimal
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// coloring.
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//
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// Following the first principle, interfering checking revolves around the
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// LiveIntervalUnion data structure.
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//
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// To fulfill the second principle, the basic allocator provides a driver for
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// incremental splitting. It essentially punts on the problem of register
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// coloring, instead driving the assignment of virtual to physical registers by
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// the cost of splitting. The basic allocator allows for heuristic reassignment
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// of registers, if a more sophisticated allocator chooses to do that.
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//
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// This framework provides a way to engineer the compile time vs. code
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// quality trade-off without relying on a particular theoretical solver.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_REGALLOCBASE
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#define LLVM_CODEGEN_REGALLOCBASE
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#include "LiveIntervalUnion.h"
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#include "llvm/CodeGen/RegisterClassInfo.h"
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#include "llvm/ADT/OwningPtr.h"
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namespace llvm {
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template<typename T> class SmallVectorImpl;
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class TargetRegisterInfo;
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class VirtRegMap;
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class LiveIntervals;
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class LiveRegMatrix;
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class Spiller;
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/// RegAllocBase provides the register allocation driver and interface that can
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/// be extended to add interesting heuristics.
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///
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/// Register allocators must override the selectOrSplit() method to implement
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/// live range splitting. They must also override enqueue/dequeue to provide an
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/// assignment order.
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class RegAllocBase {
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protected:
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const TargetRegisterInfo *TRI;
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MachineRegisterInfo *MRI;
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VirtRegMap *VRM;
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LiveIntervals *LIS;
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LiveRegMatrix *Matrix;
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RegisterClassInfo RegClassInfo;
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RegAllocBase(): TRI(0), MRI(0), VRM(0), LIS(0), Matrix(0) {}
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virtual ~RegAllocBase() {}
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// A RegAlloc pass should call this before allocatePhysRegs.
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void init(VirtRegMap &vrm, LiveIntervals &lis, LiveRegMatrix &mat);
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// The top-level driver. The output is a VirtRegMap that us updated with
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// physical register assignments.
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void allocatePhysRegs();
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// Get a temporary reference to a Spiller instance.
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virtual Spiller &spiller() = 0;
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/// enqueue - Add VirtReg to the priority queue of unassigned registers.
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virtual void enqueue(LiveInterval *LI) = 0;
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/// dequeue - Return the next unassigned register, or NULL.
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virtual LiveInterval *dequeue() = 0;
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// A RegAlloc pass should override this to provide the allocation heuristics.
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// Each call must guarantee forward progess by returning an available PhysReg
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// or new set of split live virtual registers. It is up to the splitter to
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// converge quickly toward fully spilled live ranges.
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virtual unsigned selectOrSplit(LiveInterval &VirtReg,
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SmallVectorImpl<LiveInterval*> &splitLVRs) = 0;
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// Use this group name for NamedRegionTimer.
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static const char *TimerGroupName;
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public:
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/// VerifyEnabled - True when -verify-regalloc is given.
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static bool VerifyEnabled;
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private:
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void seedLiveRegs();
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};
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} // end namespace llvm
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#endif // !defined(LLVM_CODEGEN_REGALLOCBASE)
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