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/MachineBasicBlock.h"
16 #include "llvm/CodeGen/MachineFrameInfo.h"
17 #include "llvm/CodeGen/MachineFunction.h"
18 #include "llvm/CodeGen/MachineInstrBundle.h"
19 #include "llvm/CodeGen/MachineOperand.h"
20 #include "llvm/MC/MCRegisterInfo.h"
21 #include "llvm/Target/TargetRegisterInfo.h"
22 
23 using namespace llvm;
24 
25 void LiveRegUnits::removeRegsNotPreserved(const uint32_t *RegMask) {
26   for (unsigned U = 0, E = TRI->getNumRegUnits(); U != E; ++U) {
27     for (MCRegUnitRootIterator RootReg(U, TRI); RootReg.isValid(); ++RootReg) {
28       if (MachineOperand::clobbersPhysReg(RegMask, *RootReg))
29         Units.reset(U);
30     }
31   }
32 }
33 
34 void LiveRegUnits::addRegsInMask(const uint32_t *RegMask) {
35   for (unsigned U = 0, E = TRI->getNumRegUnits(); U != E; ++U) {
36     for (MCRegUnitRootIterator RootReg(U, TRI); RootReg.isValid(); ++RootReg) {
37       if (MachineOperand::clobbersPhysReg(RegMask, *RootReg))
38         Units.set(U);
39     }
40   }
41 }
42 
43 void LiveRegUnits::stepBackward(const MachineInstr &MI) {
44   // Remove defined registers and regmask kills from the set.
45   for (ConstMIBundleOperands O(MI); O.isValid(); ++O) {
46     if (O->isReg()) {
47       if (!O->isDef())
48         continue;
49       unsigned Reg = O->getReg();
50       if (!TargetRegisterInfo::isPhysicalRegister(Reg))
51         continue;
52       removeReg(Reg);
53     } else if (O->isRegMask())
54       removeRegsNotPreserved(O->getRegMask());
55   }
56 
57   // Add uses to the set.
58   for (ConstMIBundleOperands O(MI); O.isValid(); ++O) {
59     if (!O->isReg() || !O->readsReg())
60       continue;
61     unsigned Reg = O->getReg();
62     if (!TargetRegisterInfo::isPhysicalRegister(Reg))
63       continue;
64     addReg(Reg);
65   }
66 }
67 
68 void LiveRegUnits::accumulateBackward(const MachineInstr &MI) {
69   // Add defs, uses and regmask clobbers to the set.
70   for (ConstMIBundleOperands O(MI); O.isValid(); ++O) {
71     if (O->isReg()) {
72       unsigned Reg = O->getReg();
73       if (!TargetRegisterInfo::isPhysicalRegister(Reg))
74         continue;
75       if (!O->isDef() && !O->readsReg())
76         continue;
77       addReg(Reg);
78     } else if (O->isRegMask())
79       addRegsInMask(O->getRegMask());
80   }
81 }
82 
83 /// Add live-in registers of basic block \p MBB to \p LiveUnits.
84 static void addLiveIns(LiveRegUnits &LiveUnits, const MachineBasicBlock &MBB) {
85   for (const auto &LI : MBB.liveins())
86     LiveUnits.addRegMasked(LI.PhysReg, LI.LaneMask);
87 }
88 
89 static void addLiveOuts(LiveRegUnits &LiveUnits, const MachineBasicBlock &MBB) {
90   // To get the live-outs we simply merge the live-ins of all successors.
91   for (const MachineBasicBlock *Succ : MBB.successors())
92     addLiveIns(LiveUnits, *Succ);
93 }
94 
95 /// Add pristine registers to the given \p LiveUnits. This function removes
96 /// actually saved callee save registers when \p InPrologueEpilogue is false.
97 static void removeSavedRegs(LiveRegUnits &LiveUnits, const MachineFunction &MF,
98                             const MachineFrameInfo &MFI,
99                             const TargetRegisterInfo &TRI) {
100   for (const CalleeSavedInfo &Info : MFI.getCalleeSavedInfo())
101     LiveUnits.removeReg(Info.getReg());
102 }
103 
104 void LiveRegUnits::addLiveOuts(const MachineBasicBlock &MBB) {
105   const MachineFunction &MF = *MBB.getParent();
106   const MachineFrameInfo &MFI = MF.getFrameInfo();
107   if (MFI.isCalleeSavedInfoValid()) {
108     for (const MCPhysReg *I = TRI->getCalleeSavedRegs(&MF); *I; ++I)
109       addReg(*I);
110     if (!MBB.isReturnBlock())
111       removeSavedRegs(*this, MF, MFI, *TRI);
112   }
113   ::addLiveOuts(*this, MBB);
114 }
115 
116 void LiveRegUnits::addLiveIns(const MachineBasicBlock &MBB) {
117   const MachineFunction &MF = *MBB.getParent();
118   const MachineFrameInfo &MFI = MF.getFrameInfo();
119   if (MFI.isCalleeSavedInfoValid()) {
120     for (const MCPhysReg *I = TRI->getCalleeSavedRegs(&MF); *I; ++I)
121       addReg(*I);
122     if (&MBB != &MF.front())
123       removeSavedRegs(*this, MF, MFI, *TRI);
124   }
125   ::addLiveIns(*this, MBB);
126 }
127