1 //===------ CFIInstrInserter.cpp - Insert additional CFI instructions -----===//
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
10 /// blocks. CFA information is information about offset and register set by CFI
15 /// don't. CFI instructions are inserted if basic blocks have incorrect offset
16 /// or register set by previous blocks, as a result of a non-linear layout of
18 //===----------------------------------------------------------------------===//
31 static cl::opt<bool> VerifyCFI("verify-cfiinstrs",
70     /// Value of cfa offset valid at basic block entry.
71     int64_t IncomingCFAOffset = -1;
72     /// Value of cfa offset valid at basic block exit.
73     int64_t OutgoingCFAOffset = -1;
82     /// If in/out cfa offset and register values for this block have already
89   /// contains the location where CSR register is saved.
92         : Reg(R), Offset(O) {}  in CSRSavedLocation()
94     std::optional<int> Offset;  member
97   /// Contains cfa offset and register values valid at entry and exit of basic
104   /// Calculate cfa offset and register values valid at entry and exit for all
107   /// Calculate cfa offset and register values valid at basic block exit by
111   /// Update in/out cfa offset and register values for successors of the basic
120   /// Return the cfa offset value that should be set at the beginning of a MBB
122   /// set absolute offset.
124     return MBBVector[MBB->getNumber()].IncomingCFAOffset;  in getCorrectCFAOffset()
129   /// Go through each MBB in a function and check that outgoing offset and
130   /// register of its predecessors match incoming offset and register of that
131   /// MBB, as well as that incoming offset and register of its successors match
132   /// outgoing offset and register of the MBB.
138 INITIALIZE_PASS(CFIInstrInserter, "cfi-instr-inserter",
145   // Initial CFA offset value i.e. the one valid at the beginning of the  in calculateCFAInfo()
148       MF.getSubtarget().getFrameLowering()->getInitialCFAOffset(MF);  in calculateCFAInfo()
152       MF.getSubtarget().getFrameLowering()->getInitialCFARegister(MF);  in calculateCFAInfo()
171   // i.e. that it has initial cfa offset and register values as incoming CFA  in calculateCFAInfo()
177   // Outgoing cfa offset set by the block.  in calculateOutgoingCFAInfo()
181   MachineFunction *MF = MBBInfo.MBB->getParent();  in calculateOutgoingCFAInfo()
182   const std::vector<MCCFIInstruction> &Instrs = MF->getFrameInstructions();  in calculateOutgoingCFAInfo()
183   const TargetRegisterInfo &TRI = *MF->getSubtarget().getRegisterInfo();  in calculateOutgoingCFAInfo()
187   // Determine cfa offset and register set by the block.  in calculateOutgoingCFAInfo()
215         CSROffset = CFI.getOffset() - SetOffset;  in calculateOutgoingCFAInfo()
259         } else if (It->second.Reg != CSRReg || It->second.Offset != CSROffset) {  in calculateOutgoingCFAInfo()
260           llvm_unreachable("Different saved locations for the same CSR");  in calculateOutgoingCFAInfo()
273   // Update outgoing CSR info.  in calculateOutgoingCFAInfo()
285     MBBCFAInfo &CurrentInfo = MBBVector[Current->getNumber()];  in updateSuccCFAInfo()
287     for (auto *Succ : CurrentInfo.MBB->successors()) {  in updateSuccCFAInfo()
288       MBBCFAInfo &SuccInfo = MBBVector[Succ->getNumber()];  in updateSuccCFAInfo()
310     auto MBBI = MBBInfo.MBB->begin();  in insertCFIInstrs()
311     DebugLoc DL = MBBInfo.MBB->findDebugLoc(MBBI);  in insertCFIInstrs()
317     if ((PrevMBBInfo->OutgoingCFAOffset != MBBInfo.IncomingCFAOffset &&  in insertCFIInstrs()
318          PrevMBBInfo->OutgoingCFARegister != MBBInfo.IncomingCFARegister) ||  in insertCFIInstrs()
320       // If both outgoing offset and register of a previous block don't match  in insertCFIInstrs()
321       // incoming offset and register of this block, or if this block begins a  in insertCFIInstrs()
322       // section, add a def_cfa instruction with the correct offset and  in insertCFIInstrs()
326       BuildMI(*MBBInfo.MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))  in insertCFIInstrs()
329     } else if (PrevMBBInfo->OutgoingCFAOffset != MBBInfo.IncomingCFAOffset) {  in insertCFIInstrs()
330       // If outgoing offset of a previous block doesn't match incoming offset  in insertCFIInstrs()
332       // offset for this block.  in insertCFIInstrs()
335       BuildMI(*MBBInfo.MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))  in insertCFIInstrs()
338     } else if (PrevMBBInfo->OutgoingCFARegister !=  in insertCFIInstrs()
343       BuildMI(*MBBInfo.MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))  in insertCFIInstrs()
349       MF.getSubtarget().getFrameLowering()->emitCalleeSavedFrameMovesFullCFA(  in insertCFIInstrs()
357                      PrevMBBInfo->OutgoingCSRSaved, MBBInfo.IncomingCSRSaved);  in insertCFIInstrs()
361       BuildMI(*MBBInfo.MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))  in insertCFIInstrs()
367                      MBBInfo.IncomingCSRSaved, PrevMBBInfo->OutgoingCSRSaved);  in insertCFIInstrs()
372       CSRSavedLocation RO = it->second;  in insertCFIInstrs()
373       if (!RO.Reg && RO.Offset) {  in insertCFIInstrs()
375             MCCFIInstruction::createOffset(nullptr, Reg, *RO.Offset));  in insertCFIInstrs()
376       } else if (RO.Reg && !RO.Offset) {  in insertCFIInstrs()
380         llvm_unreachable("RO.Reg and RO.Offset cannot both be valid/invalid");  in insertCFIInstrs()
382       BuildMI(*MBBInfo.MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))  in insertCFIInstrs()
394   errs() << "*** Inconsistent CFA register and/or offset between pred and succ "  in reportCFAError()
396   errs() << "Pred: " << Pred.MBB->getName() << " #" << Pred.MBB->getNumber()  in reportCFAError()
397          << " in " << Pred.MBB->getParent()->getName()  in reportCFAError()
399   errs() << "Pred: " << Pred.MBB->getName() << " #" << Pred.MBB->getNumber()  in reportCFAError()
400          << " in " << Pred.MBB->getParent()->getName()  in reportCFAError()
401          << " outgoing CFA Offset:" << Pred.OutgoingCFAOffset << "\n";  in reportCFAError()
402   errs() << "Succ: " << Succ.MBB->getName() << " #" << Succ.MBB->getNumber()  in reportCFAError()
404   errs() << "Succ: " << Succ.MBB->getName() << " #" << Succ.MBB->getNumber()  in reportCFAError()
405          << " incoming CFA Offset:" << Succ.IncomingCFAOffset << "\n";  in reportCFAError()
410   errs() << "*** Inconsistent CSR Saved between pred and succ in function "  in reportCSRError()
411          << Pred.MBB->getParent()->getName() << " ***\n";  in reportCSRError()
412   errs() << "Pred: " << Pred.MBB->getName() << " #" << Pred.MBB->getNumber()  in reportCSRError()
413          << " outgoing CSR Saved: ";  in reportCSRError()
417   errs() << "Succ: " << Succ.MBB->getName() << " #" << Succ.MBB->getNumber()  in reportCSRError()
418          << " incoming CSR Saved: ";  in reportCSRError()
427     const MBBCFAInfo &CurrMBBInfo = MBBVector[CurrMBB->getNumber()];  in verify()
428     for (MachineBasicBlock *Succ : CurrMBB->successors()) {  in verify()
429       const MBBCFAInfo &SuccMBBInfo = MBBVector[Succ->getNumber()];  in verify()
430       // Check that incoming offset and register values of successors match the  in verify()
431       // outgoing offset and register values of CurrMBB  in verify()
436         if (SuccMBBInfo.MBB->succ_empty() && !SuccMBBInfo.MBB->isReturnBlock())  in verify()