1 //===--- LivePhysRegs.cpp - Live Physical Register Set --------------------===//
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 the LivePhysRegs utility for tracking liveness of
11 // physical registers across machine instructions in forward or backward order.
12 // A more detailed description can be found in the corresponding header file.
14 //===----------------------------------------------------------------------===//
16 #include "llvm/CodeGen/LivePhysRegs.h"
17 #include "llvm/CodeGen/MachineInstrBundle.h"
18 #include "llvm/Support/Debug.h"
19 #include "llvm/Support/raw_ostream.h"
23 /// \brief Remove all registers from the set that get clobbered by the register
25 void LivePhysRegs::removeRegsInMask(const MachineOperand &MO) {
26 SparseSet<unsigned>::iterator LRI = LiveRegs.begin();
27 while (LRI != LiveRegs.end()) {
28 if (MO.clobbersPhysReg(*LRI))
29 LRI = LiveRegs.erase(LRI);
35 /// Simulates liveness when stepping backwards over an instruction(bundle):
36 /// Remove Defs, add uses. This is the recommended way of calculating liveness.
37 void LivePhysRegs::stepBackward(const MachineInstr &MI) {
38 // Remove defined registers and regmask kills from the set.
39 for (ConstMIBundleOperands O(&MI); O.isValid(); ++O) {
43 unsigned Reg = O->getReg();
47 } else if (O->isRegMask())
51 // Add uses to the set.
52 for (ConstMIBundleOperands O(&MI); O.isValid(); ++O) {
53 if (!O->isReg() || !O->readsReg() || O->isUndef())
55 unsigned Reg = O->getReg();
62 /// Simulates liveness when stepping forward over an instruction(bundle): Remove
63 /// killed-uses, add defs. This is the not recommended way, because it depends
64 /// on accurate kill flags. If possible use stepBackwards() instead of this
66 void LivePhysRegs::stepForward(const MachineInstr &MI) {
67 SmallVector<unsigned, 4> Defs;
68 // Remove killed registers from the set.
69 for (ConstMIBundleOperands O(&MI); O.isValid(); ++O) {
71 unsigned Reg = O->getReg();
83 } else if (O->isRegMask())
87 // Add defs to the set.
88 for (unsigned i = 0, e = Defs.size(); i != e; ++i)
92 /// Prin the currently live registers to OS.
93 void LivePhysRegs::print(raw_ostream &OS) const {
94 OS << "Live Registers:";
96 OS << " (uninitialized)\n";
105 for (const_iterator I = begin(), E = end(); I != E; ++I)
106 OS << " " << PrintReg(*I, TRI);
110 /// Dumps the currently live registers to the debug output.
111 void LivePhysRegs::dump() const {
112 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
113 dbgs() << " " << *this;