/// Compute the sets of entry and return blocks for saving and restoring
/// callee-saved registers, and placing prolog and epilog code.
void PEI::calculateSaveRestoreBlocks(MachineFunction &MF) {
const MachineFrameInfo &MFI = MF.getFrameInfo();
// Even when we do not change any CSR, we still want to insert the
// prologue and epilogue of the function.
// So set the save points for those.
// Use the points found by shrink-wrapping, if any.
if (MFI.getSavePoint()) {
SaveBlocks.push_back(MFI.getSavePoint());
assert(MFI.getRestorePoint() && "Both restore and save must be set");
MachineBasicBlock *RestoreBlock = MFI.getRestorePoint();
// If RestoreBlock does not have any successor and is not a return block
// then the end point is unreachable and we do not need to insert any
// epilogue.
if (!RestoreBlock->succ_empty() || RestoreBlock->isReturnBlock())
RestoreBlocks.push_back(RestoreBlock);
return;
}
// Save refs to entry and return blocks.
SaveBlocks.push_back(&MF.front());
for (MachineBasicBlock &MBB : MF) {
if (MBB.isEHFuncletEntry())
SaveBlocks.push_back(&MBB);
if (MBB.isReturnBlock())
RestoreBlocks.push_back(&MBB);
}
}
void LivePhysRegs::addLiveOuts(const MachineBasicBlock &MBB) {
const MachineFunction &MF = *MBB.getParent();
const MachineFrameInfo &MFI = *MF.getFrameInfo();
if (MFI.isCalleeSavedInfoValid()) {
if (MBB.isReturnBlock()) {
// The return block has no successors whose live-ins we could merge
// below. So instead we add the callee saved registers manually.
for (const MCPhysReg *I = TRI->getCalleeSavedRegs(&MF); *I; ++I)
addReg(*I);
} else {
addPristines(*this, MF, MFI, *TRI);
}
}
addLiveOutsNoPristines(MBB);
}
void LiveRegUnits::addLiveOuts(const MachineBasicBlock &MBB) {
const MachineFunction &MF = *MBB.getParent();
addPristines(MF);
// To get the live-outs we simply merge the live-ins of all successors.
for (const MachineBasicBlock *Succ : MBB.successors())
addBlockLiveIns(*this, *Succ);
// For the return block: Add all callee saved registers.
if (MBB.isReturnBlock()) {
const MachineFrameInfo &MFI = MF.getFrameInfo();
if (MFI.isCalleeSavedInfoValid())
addCalleeSavedRegs(*this, MF);
}
}
/// Compute the sets of entry and return blocks for saving and restoring
/// callee-saved registers, and placing prolog and epilog code.
void PEI::calculateSaveRestoreBlocks(MachineFunction &Fn) {
MachineFrameInfo &MFI = Fn.getFrameInfo();
const TargetFrameLowering *TFI = Fn.getSubtarget().getFrameLowering();
// Even when we do not change any CSR, we still want to insert the
// prologue and epilogue of the function.
// So set the save points for those.
// Use the points found by shrink-wrapping, if any.
if (MFI.getSavePoint()) {
SaveBlocks.push_back(MFI.getSavePoint());
assert(MFI.getRestorePoint() && "Both restore and save must be set");
MachineBasicBlock *RestoreBlock = MFI.getRestorePoint();
// If RestoreBlock does not have any successor and is not a return block
// then the end point is unreachable and we do not need to insert any
// epilogue.
if (!RestoreBlock->succ_empty() || RestoreBlock->isReturnBlock())
RestoreBlocks.push_back(RestoreBlock);
// If we are adding return protectors ensure we can find a free register
if (MFI.hasReturnProtector() &&
!TFI->determineReturnProtectorTempRegister(Fn, SaveBlocks, RestoreBlocks)) {
// Shrinkwrapping will prevent finding a free register
SaveBlocks.clear();
RestoreBlocks.clear();
MFI.setSavePoint(nullptr);
MFI.setRestorePoint(nullptr);
} else {
return;
}
}
// Save refs to entry and return blocks.
SaveBlocks.push_back(&Fn.front());
for (MachineBasicBlock &MBB : Fn) {
if (MBB.isEHFuncletEntry())
SaveBlocks.push_back(&MBB);
if (MBB.isReturnBlock())
RestoreBlocks.push_back(&MBB);
}
if (MFI.hasReturnProtector())
TFI->determineReturnProtectorTempRegister(Fn, SaveBlocks, RestoreBlocks);
}
