//
// This file implements the LivePhysRegs utility for tracking liveness of
// physical registers across machine instructions in forward or backward order.
+// A more detailed description can be found in the corresponding header file.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/LivePhysRegs.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBundle.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
using namespace llvm;
-/// We assume the high bits of a physical super-register are not preserved
-/// unless the instruction has an implicit-use operand reading the
-/// super-register.
-
/// \brief Remove all registers from the set that get clobbered by the register
/// mask.
-void LivePhysRegs::removeRegsInMask(const MachineOperand &MO) {
+/// The clobbers set will be the list of live registers clobbered
+/// by the regmask.
+void LivePhysRegs::removeRegsInMask(const MachineOperand &MO,
+ SmallVectorImpl<std::pair<unsigned, const MachineOperand*>> *Clobbers) {
SparseSet<unsigned>::iterator LRI = LiveRegs.begin();
while (LRI != LiveRegs.end()) {
- if (MO.clobbersPhysReg(*LRI))
+ if (MO.clobbersPhysReg(*LRI)) {
+ if (Clobbers)
+ Clobbers->push_back(std::make_pair(*LRI, &MO));
LRI = LiveRegs.erase(LRI);
- else
+ } else
++LRI;
}
}
continue;
removeReg(Reg);
} else if (O->isRegMask())
- removeRegsInMask(*O);
+ removeRegsInMask(*O, nullptr);
}
// Add uses to the set.
/// killed-uses, add defs. This is the not recommended way, because it depends
/// on accurate kill flags. If possible use stepBackwards() instead of this
/// function.
-void LivePhysRegs::stepForward(const MachineInstr &MI) {
- SmallVector<unsigned, 4> Defs;
+void LivePhysRegs::stepForward(const MachineInstr &MI,
+ SmallVectorImpl<std::pair<unsigned, const MachineOperand*>> &Clobbers) {
// Remove killed registers from the set.
for (ConstMIBundleOperands O(&MI); O.isValid(); ++O) {
if (O->isReg()) {
if (Reg == 0)
continue;
if (O->isDef()) {
- if (!O->isDead())
- Defs.push_back(Reg);
+ // Note, dead defs are still recorded. The caller should decide how to
+ // handle them.
+ Clobbers.push_back(std::make_pair(Reg, &*O));
} else {
if (!O->isKill())
continue;
removeReg(Reg);
}
} else if (O->isRegMask())
- removeRegsInMask(*O);
+ removeRegsInMask(*O, &Clobbers);
}
// Add defs to the set.
- for (unsigned i = 0, e = Defs.size(); i != e; ++i)
- addReg(Defs[i]);
+ for (auto Reg : Clobbers) {
+ // Skip dead defs. They shouldn't be added to the set.
+ if (Reg.second->isReg() && Reg.second->isDead())
+ continue;
+ addReg(Reg.first);
+ }
+}
+
+/// Prin the currently live registers to OS.
+void LivePhysRegs::print(raw_ostream &OS) const {
+ OS << "Live Registers:";
+ if (!TRI) {
+ OS << " (uninitialized)\n";
+ return;
+ }
+
+ if (empty()) {
+ OS << " (empty)\n";
+ return;
+ }
+
+ for (const_iterator I = begin(), E = end(); I != E; ++I)
+ OS << " " << PrintReg(*I, TRI);
+ OS << "\n";
+}
+
+/// Dumps the currently live registers to the debug output.
+void LivePhysRegs::dump() const {
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+ dbgs() << " " << *this;
+#endif
+}
+
+/// Add live-in registers of basic block \p MBB to \p LiveRegs.
+static void addLiveIns(LivePhysRegs &LiveRegs, const MachineBasicBlock &MBB) {
+ for (unsigned Reg : make_range(MBB.livein_begin(), MBB.livein_end()))
+ LiveRegs.addReg(Reg);
+}
+
+/// Add pristine registers to the given \p LiveRegs. This function removes
+/// actually saved callee save registers when \p InPrologueEpilogue is false.
+static void addPristines(LivePhysRegs &LiveRegs, const MachineFunction &MF,
+ const TargetRegisterInfo &TRI) {
+ const MachineFrameInfo &MFI = *MF.getFrameInfo();
+ if (!MFI.isCalleeSavedInfoValid())
+ return;
+
+ for (const MCPhysReg *CSR = TRI.getCalleeSavedRegs(&MF); CSR && *CSR; ++CSR)
+ LiveRegs.addReg(*CSR);
+ for (const CalleeSavedInfo &Info : MFI.getCalleeSavedInfo())
+ LiveRegs.removeReg(Info.getReg());
+}
+
+void LivePhysRegs::addLiveOuts(const MachineBasicBlock *MBB,
+ bool AddPristines) {
+ if (AddPristines) {
+ const MachineFunction &MF = *MBB->getParent();
+ addPristines(*this, MF, *TRI);
+ }
+ for (const MachineBasicBlock *Succ : MBB->successors())
+ ::addLiveIns(*this, *Succ);
+}
+
+void LivePhysRegs::addLiveIns(const MachineBasicBlock *MBB,
+ bool AddPristines) {
+ if (AddPristines) {
+ const MachineFunction &MF = *MBB->getParent();
+ addPristines(*this, MF, *TRI);
+ }
+ ::addLiveIns(*this, *MBB);
}