MachineRegisterInfo.cpp revision 11a26f3697ea6520022ea6d3fa6a07b3c1b988cd 
1//===-- lib/Codegen/MachineRegisterInfo.cpp -------------------------------===//
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// Implementation of the MachineRegisterInfo class.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/CodeGen/MachineRegisterInfo.h"
15using namespace llvm;
16
17MachineRegisterInfo::MachineRegisterInfo(const TargetRegisterInfo &TRI) {
18  VRegInfo.reserve(256);
19  RegClass2VRegMap.resize(TRI.getNumRegClasses()+1); // RC ID starts at 1.
20  UsedPhysRegs.resize(TRI.getNumRegs());
21
22  // Create the physreg use/def lists.
23  PhysRegUseDefLists = new MachineOperand*[TRI.getNumRegs()];
24  memset(PhysRegUseDefLists, 0, sizeof(MachineOperand*)*TRI.getNumRegs());
25}
26
27MachineRegisterInfo::~MachineRegisterInfo() {
28#ifndef NDEBUG
29  for (unsigned i = 0, e = VRegInfo.size(); i != e; ++i)
30    assert(VRegInfo[i].second == 0 && "Vreg use list non-empty still?");
31  for (unsigned i = 0, e = UsedPhysRegs.size(); i != e; ++i)
32    assert(!PhysRegUseDefLists[i] &&
33           "PhysRegUseDefLists has entries after all instructions are deleted");
34#endif
35  delete [] PhysRegUseDefLists;
36}
37
38/// HandleVRegListReallocation - We just added a virtual register to the
39/// VRegInfo info list and it reallocated.  Update the use/def lists info
40/// pointers.
41void MachineRegisterInfo::HandleVRegListReallocation() {
42  // The back pointers for the vreg lists point into the previous vector.
43  // Update them to point to their correct slots.
44  for (unsigned i = 0, e = VRegInfo.size(); i != e; ++i) {
45    MachineOperand *List = VRegInfo[i].second;
46    if (!List) continue;
47    // Update the back-pointer to be accurate once more.
48    List->Contents.Reg.Prev = &VRegInfo[i].second;
49  }
50}
51
52/// replaceRegWith - Replace all instances of FromReg with ToReg in the
53/// machine function.  This is like llvm-level X->replaceAllUsesWith(Y),
54/// except that it also changes any definitions of the register as well.
55void MachineRegisterInfo::replaceRegWith(unsigned FromReg, unsigned ToReg) {
56  assert(FromReg != ToReg && "Cannot replace a reg with itself");
57
58  // TODO: This could be more efficient by bulk changing the operands.
59  for (reg_iterator I = reg_begin(FromReg), E = reg_end(); I != E; ) {
60    MachineOperand &O = I.getOperand();
61    ++I;
62    O.setReg(ToReg);
63  }
64}
65
66
67/// getVRegDef - Return the machine instr that defines the specified virtual
68/// register or null if none is found.  This assumes that the code is in SSA
69/// form, so there should only be one definition.
70MachineInstr *MachineRegisterInfo::getVRegDef(unsigned Reg) const {
71  assert(Reg-TargetRegisterInfo::FirstVirtualRegister < VRegInfo.size() &&
72         "Invalid vreg!");
73  for (reg_iterator I = reg_begin(Reg), E = reg_end(); I != E; ++I) {
74    // Since we are in SSA form, we can stop at the first definition.
75    if (I.getOperand().isDef())
76      return &*I;
77  }
78  return 0;
79}
80
81
82#ifndef NDEBUG
83void MachineRegisterInfo::dumpUses(unsigned Reg) const {
84  for (use_iterator I = use_begin(Reg), E = use_end(); I != E; ++I)
85    I.getOperand().getParent()->dump();
86}
87#endif
88