AllocationOrder.cpp revision 296417 
1//===-- llvm/CodeGen/AllocationOrder.cpp - Allocation Order ---------------===//
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 implements an allocation order for virtual registers.
11//
12// The preferred allocation order for a virtual register depends on allocation
13// hints and target hooks. The AllocationOrder class encapsulates all of that.
14//
15//===----------------------------------------------------------------------===//
16
17#include "AllocationOrder.h"
18#include "llvm/CodeGen/MachineFunction.h"
19#include "llvm/CodeGen/MachineRegisterInfo.h"
20#include "llvm/CodeGen/RegisterClassInfo.h"
21#include "llvm/CodeGen/VirtRegMap.h"
22#include "llvm/Support/Debug.h"
23#include "llvm/Support/raw_ostream.h"
24
25using namespace llvm;
26
27#define DEBUG_TYPE "regalloc"
28
29// Compare VirtRegMap::getRegAllocPref().
30AllocationOrder::AllocationOrder(unsigned VirtReg,
31                                 const VirtRegMap &VRM,
32                                 const RegisterClassInfo &RegClassInfo,
33                                 const LiveRegMatrix *Matrix)
34  : Pos(0) {
35  const MachineFunction &MF = VRM.getMachineFunction();
36  const TargetRegisterInfo *TRI = &VRM.getTargetRegInfo();
37  Order = RegClassInfo.getOrder(MF.getRegInfo().getRegClass(VirtReg));
38  TRI->getRegAllocationHints(VirtReg, Order, Hints, MF, &VRM, Matrix);
39  rewind();
40
41  DEBUG({
42    if (!Hints.empty()) {
43      dbgs() << "hints:";
44      for (unsigned I = 0, E = Hints.size(); I != E; ++I)
45        dbgs() << ' ' << PrintReg(Hints[I], TRI);
46      dbgs() << '\n';
47    }
48  });
49#ifndef NDEBUG
50  for (unsigned I = 0, E = Hints.size(); I != E; ++I)
51    assert(std::find(Order.begin(), Order.end(), Hints[I]) != Order.end() &&
52           "Target hint is outside allocation order.");
53#endif
54}
55