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_LIB_CODEGEN_ALLOCATIONORDER_H
18 #define LLVM_LIB_CODEGEN_ALLOCATIONORDER_H
20 #include "llvm/ADT/ArrayRef.h"
21 #include "llvm/MC/MCRegisterInfo.h"
25 class RegisterClassInfo;
29 class LLVM_LIBRARY_VISIBILITY AllocationOrder {
30 SmallVector<MCPhysReg, 16> Hints;
31 ArrayRef<MCPhysReg> Order;
35 /// Create a new AllocationOrder for VirtReg.
36 /// @param VirtReg Virtual register to allocate for.
37 /// @param VRM Virtual register map for function.
38 /// @param RegClassInfo Information about reserved and allocatable registers.
39 AllocationOrder(unsigned VirtReg,
40 const VirtRegMap &VRM,
41 const RegisterClassInfo &RegClassInfo,
42 const LiveRegMatrix *Matrix);
44 /// Get the allocation order without reordered hints.
45 ArrayRef<MCPhysReg> getOrder() const { return Order; }
47 /// Return the next physical register in the allocation order, or 0.
48 /// It is safe to call next() again after it returned 0, it will keep
49 /// returning 0 until rewind() is called.
50 unsigned next(unsigned Limit = 0) {
52 return Hints.end()[Pos++];
55 while (Pos < int(Limit)) {
56 unsigned Reg = Order[Pos++];
63 /// As next(), but allow duplicates to be returned, and stop before the
64 /// Limit'th register in the RegisterClassInfo allocation order.
66 /// This can produce more than Limit registers if there are hints.
67 unsigned nextWithDups(unsigned Limit) {
69 return Hints.end()[Pos++];
75 /// Start over from the beginning.
76 void rewind() { Pos = -int(Hints.size()); }
78 /// Return true if the last register returned from next() was a preferred register.
79 bool isHint() const { return Pos <= 0; }
81 /// Return true if PhysReg is a preferred register.
82 bool isHint(unsigned PhysReg) const {
83 return std::find(Hints.begin(), Hints.end(), PhysReg) != Hints.end();
87 } // end namespace llvm