1 //===--- LiveRegUnits.cpp - Register Unit Set -----------------------------===//
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 /// \file This file imlements the LiveRegUnits set.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/CodeGen/LiveRegUnits.h"
15 #include "llvm/CodeGen/MachineFrameInfo.h"
16 #include "llvm/CodeGen/MachineFunction.h"
17 #include "llvm/CodeGen/MachineInstrBundle.h"
18 using namespace llvm;
19 
20 void LiveRegUnits::removeRegsNotPreserved(const uint32_t *RegMask) {
21   for (unsigned U = 0, E = TRI->getNumRegUnits(); U != E; ++U) {
22     for (MCRegUnitRootIterator RootReg(U, TRI); RootReg.isValid(); ++RootReg) {
23       if (MachineOperand::clobbersPhysReg(RegMask, *RootReg))
24         Units.reset(U);
25     }
26   }
27 }
28 
29 void LiveRegUnits::addRegsInMask(const uint32_t *RegMask) {
30   for (unsigned U = 0, E = TRI->getNumRegUnits(); U != E; ++U) {
31     for (MCRegUnitRootIterator RootReg(U, TRI); RootReg.isValid(); ++RootReg) {
32       if (MachineOperand::clobbersPhysReg(RegMask, *RootReg))
33         Units.set(U);
34     }
35   }
36 }
37 
38 void LiveRegUnits::stepBackward(const MachineInstr &MI) {
39   // Remove defined registers and regmask kills from the set.
40   for (ConstMIBundleOperands O(MI); O.isValid(); ++O) {
41     if (O->isReg()) {
42       if (!O->isDef())
43         continue;
44       unsigned Reg = O->getReg();
45       if (!TargetRegisterInfo::isPhysicalRegister(Reg))
46         continue;
47       removeReg(Reg);
48     } else if (O->isRegMask())
49       removeRegsNotPreserved(O->getRegMask());
50   }
51 
52   // Add uses to the set.
53   for (ConstMIBundleOperands O(MI); O.isValid(); ++O) {
54     if (!O->isReg() || !O->readsReg())
55       continue;
56     unsigned Reg = O->getReg();
57     if (!TargetRegisterInfo::isPhysicalRegister(Reg))
58       continue;
59     addReg(Reg);
60   }
61 }
62 
63 void LiveRegUnits::accumulateBackward(const MachineInstr &MI) {
64   // Add defs, uses and regmask clobbers to the set.
65   for (ConstMIBundleOperands O(MI); O.isValid(); ++O) {
66     if (O->isReg()) {
67       unsigned Reg = O->getReg();
68       if (!TargetRegisterInfo::isPhysicalRegister(Reg))
69         continue;
70       if (!O->isDef() && !O->readsReg())
71         continue;
72       addReg(Reg);
73     } else if (O->isRegMask())
74       addRegsInMask(O->getRegMask());
75   }
76 }
77 
78 /// Add live-in registers of basic block \p MBB to \p LiveUnits.
79 static void addLiveIns(LiveRegUnits &LiveUnits, const MachineBasicBlock &MBB) {
80   for (const auto &LI : MBB.liveins())
81     LiveUnits.addRegMasked(LI.PhysReg, LI.LaneMask);
82 }
83 
84 static void addLiveOuts(LiveRegUnits &LiveUnits, const MachineBasicBlock &MBB) {
85   // To get the live-outs we simply merge the live-ins of all successors.
86   for (const MachineBasicBlock *Succ : MBB.successors())
87     addLiveIns(LiveUnits, *Succ);
88 }
89 
90 /// Add pristine registers to the given \p LiveUnits. This function removes
91 /// actually saved callee save registers when \p InPrologueEpilogue is false.
92 static void removeSavedRegs(LiveRegUnits &LiveUnits, const MachineFunction &MF,
93                             const MachineFrameInfo &MFI,
94                             const TargetRegisterInfo &TRI) {
95   for (const CalleeSavedInfo &Info : MFI.getCalleeSavedInfo())
96     LiveUnits.removeReg(Info.getReg());
97 }
98 
99 void LiveRegUnits::addLiveOuts(const MachineBasicBlock &MBB) {
100   const MachineFunction &MF = *MBB.getParent();
101   const MachineFrameInfo &MFI = MF.getFrameInfo();
102   if (MFI.isCalleeSavedInfoValid()) {
103     for (const MCPhysReg *I = TRI->getCalleeSavedRegs(&MF); *I; ++I)
104       addReg(*I);
105     if (!MBB.isReturnBlock())
106       removeSavedRegs(*this, MF, MFI, *TRI);
107   }
108   ::addLiveOuts(*this, MBB);
109 }
110 
111 void LiveRegUnits::addLiveIns(const MachineBasicBlock &MBB) {
112   const MachineFunction &MF = *MBB.getParent();
113   const MachineFrameInfo &MFI = MF.getFrameInfo();
114   if (MFI.isCalleeSavedInfoValid()) {
115     for (const MCPhysReg *I = TRI->getCalleeSavedRegs(&MF); *I; ++I)
116       addReg(*I);
117     if (&MBB != &MF.front())
118       removeSavedRegs(*this, MF, MFI, *TRI);
119   }
120   ::addLiveIns(*this, MBB);
121 }
122