1 //===-- llvm/CodeGen/AllocationOrder.h - Allocation Order -*- 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 implements an allocation order for virtual registers.
12 // The preferred allocation order for a virtual register depends on allocation
13 // hints and target hooks. The AllocationOrder class encapsulates all of that.
15 //===----------------------------------------------------------------------===//
17 #ifndef LLVM_CODEGEN_ALLOCATIONORDER_H
18 #define LLVM_CODEGEN_ALLOCATIONORDER_H
22 class RegisterClassInfo;
25 class AllocationOrder {
26 const unsigned *Begin;
29 const RegisterClassInfo &RCI;
34 /// AllocationOrder - Create a new AllocationOrder for VirtReg.
35 /// @param VirtReg Virtual register to allocate for.
36 /// @param VRM Virtual register map for function.
37 /// @param RegClassInfo Information about reserved and allocatable registers.
38 AllocationOrder(unsigned VirtReg,
39 const VirtRegMap &VRM,
40 const RegisterClassInfo &RegClassInfo);
44 /// next - Return the next physical register in the allocation order, or 0.
45 /// It is safe to call next again after it returned 0.
46 /// It will keep returning 0 until rewind() is called.
48 // First take the hint.
54 // Then look at the order from TRI.
56 unsigned Reg = *Pos++;
63 /// rewind - Start over from the beginning.
64 void rewind() { Pos = 0; }
66 /// isHint - Return true if PhysReg is a preferred register.
67 bool isHint(unsigned PhysReg) const { return PhysReg == Hint; }
70 } // end namespace llvm