| //===- llvm/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp --------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "DbgValueHistoryCalculator.h" |
| #include "llvm/ADT/BitVector.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/CodeGen/MachineBasicBlock.h" |
| #include "llvm/CodeGen/MachineFunction.h" |
| #include "llvm/CodeGen/MachineInstr.h" |
| #include "llvm/CodeGen/MachineOperand.h" |
| #include "llvm/CodeGen/TargetLowering.h" |
| #include "llvm/CodeGen/TargetRegisterInfo.h" |
| #include "llvm/CodeGen/TargetSubtargetInfo.h" |
| #include "llvm/IR/DebugInfoMetadata.h" |
| #include "llvm/IR/DebugLoc.h" |
| #include "llvm/MC/MCRegisterInfo.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include <cassert> |
| #include <map> |
| #include <utility> |
| |
| using namespace llvm; |
| |
| #define DEBUG_TYPE "dwarfdebug" |
| |
| // If @MI is a DBG_VALUE with debug value described by a |
| // defined register, returns the number of this register. |
| // In the other case, returns 0. |
| static unsigned isDescribedByReg(const MachineInstr &MI) { |
| assert(MI.isDebugValue()); |
| assert(MI.getNumOperands() == 4); |
| // If location of variable is described using a register (directly or |
| // indirectly), this register is always a first operand. |
| return MI.getOperand(0).isReg() ? MI.getOperand(0).getReg() : 0; |
| } |
| |
| void DbgValueHistoryMap::startInstrRange(InlinedVariable Var, |
| const MachineInstr &MI) { |
| // Instruction range should start with a DBG_VALUE instruction for the |
| // variable. |
| assert(MI.isDebugValue() && "not a DBG_VALUE"); |
| auto &Ranges = VarInstrRanges[Var]; |
| if (!Ranges.empty() && Ranges.back().second == nullptr && |
| Ranges.back().first->isIdenticalTo(MI)) { |
| LLVM_DEBUG(dbgs() << "Coalescing identical DBG_VALUE entries:\n" |
| << "\t" << Ranges.back().first << "\t" << MI << "\n"); |
| return; |
| } |
| Ranges.push_back(std::make_pair(&MI, nullptr)); |
| } |
| |
| void DbgValueHistoryMap::endInstrRange(InlinedVariable Var, |
| const MachineInstr &MI) { |
| auto &Ranges = VarInstrRanges[Var]; |
| // Verify that the current instruction range is not yet closed. |
| assert(!Ranges.empty() && Ranges.back().second == nullptr); |
| // For now, instruction ranges are not allowed to cross basic block |
| // boundaries. |
| assert(Ranges.back().first->getParent() == MI.getParent()); |
| Ranges.back().second = &MI; |
| } |
| |
| unsigned DbgValueHistoryMap::getRegisterForVar(InlinedVariable Var) const { |
| const auto &I = VarInstrRanges.find(Var); |
| if (I == VarInstrRanges.end()) |
| return 0; |
| const auto &Ranges = I->second; |
| if (Ranges.empty() || Ranges.back().second != nullptr) |
| return 0; |
| return isDescribedByReg(*Ranges.back().first); |
| } |
| |
| namespace { |
| |
| // Maps physreg numbers to the variables they describe. |
| using InlinedVariable = DbgValueHistoryMap::InlinedVariable; |
| using RegDescribedVarsMap = std::map<unsigned, SmallVector<InlinedVariable, 1>>; |
| |
| } // end anonymous namespace |
| |
| // Claim that @Var is not described by @RegNo anymore. |
| static void dropRegDescribedVar(RegDescribedVarsMap &RegVars, unsigned RegNo, |
| InlinedVariable Var) { |
| const auto &I = RegVars.find(RegNo); |
| assert(RegNo != 0U && I != RegVars.end()); |
| auto &VarSet = I->second; |
| const auto &VarPos = llvm::find(VarSet, Var); |
| assert(VarPos != VarSet.end()); |
| VarSet.erase(VarPos); |
| // Don't keep empty sets in a map to keep it as small as possible. |
| if (VarSet.empty()) |
| RegVars.erase(I); |
| } |
| |
| // Claim that @Var is now described by @RegNo. |
| static void addRegDescribedVar(RegDescribedVarsMap &RegVars, unsigned RegNo, |
| InlinedVariable Var) { |
| assert(RegNo != 0U); |
| auto &VarSet = RegVars[RegNo]; |
| assert(!is_contained(VarSet, Var)); |
| VarSet.push_back(Var); |
| } |
| |
| // Terminate the location range for variables described by register at |
| // @I by inserting @ClobberingInstr to their history. |
| static void clobberRegisterUses(RegDescribedVarsMap &RegVars, |
| RegDescribedVarsMap::iterator I, |
| DbgValueHistoryMap &HistMap, |
| const MachineInstr &ClobberingInstr) { |
| // Iterate over all variables described by this register and add this |
| // instruction to their history, clobbering it. |
| for (const auto &Var : I->second) |
| HistMap.endInstrRange(Var, ClobberingInstr); |
| RegVars.erase(I); |
| } |
| |
| // Terminate the location range for variables described by register |
| // @RegNo by inserting @ClobberingInstr to their history. |
| static void clobberRegisterUses(RegDescribedVarsMap &RegVars, unsigned RegNo, |
| DbgValueHistoryMap &HistMap, |
| const MachineInstr &ClobberingInstr) { |
| const auto &I = RegVars.find(RegNo); |
| if (I == RegVars.end()) |
| return; |
| clobberRegisterUses(RegVars, I, HistMap, ClobberingInstr); |
| } |
| |
| // Returns the first instruction in @MBB which corresponds to |
| // the function epilogue, or nullptr if @MBB doesn't contain an epilogue. |
| static const MachineInstr *getFirstEpilogueInst(const MachineBasicBlock &MBB) { |
| auto LastMI = MBB.getLastNonDebugInstr(); |
| if (LastMI == MBB.end() || !LastMI->isReturn()) |
| return nullptr; |
| // Assume that epilogue starts with instruction having the same debug location |
| // as the return instruction. |
| DebugLoc LastLoc = LastMI->getDebugLoc(); |
| auto Res = LastMI; |
| for (MachineBasicBlock::const_reverse_iterator I = LastMI.getReverse(), |
| E = MBB.rend(); |
| I != E; ++I) { |
| if (I->getDebugLoc() != LastLoc) |
| return &*Res; |
| Res = &*I; |
| } |
| // If all instructions have the same debug location, assume whole MBB is |
| // an epilogue. |
| return &*MBB.begin(); |
| } |
| |
| // Collect registers that are modified in the function body (their |
| // contents is changed outside of the prologue and epilogue). |
| static void collectChangingRegs(const MachineFunction *MF, |
| const TargetRegisterInfo *TRI, |
| BitVector &Regs) { |
| for (const auto &MBB : *MF) { |
| auto FirstEpilogueInst = getFirstEpilogueInst(MBB); |
| |
| for (const auto &MI : MBB) { |
| // Avoid looking at prologue or epilogue instructions. |
| if (&MI == FirstEpilogueInst) |
| break; |
| if (MI.getFlag(MachineInstr::FrameSetup)) |
| continue; |
| |
| // Look for register defs and register masks. Register masks are |
| // typically on calls and they clobber everything not in the mask. |
| for (const MachineOperand &MO : MI.operands()) { |
| // Skip virtual registers since they are handled by the parent. |
| if (MO.isReg() && MO.isDef() && MO.getReg() && |
| !TRI->isVirtualRegister(MO.getReg())) { |
| for (MCRegAliasIterator AI(MO.getReg(), TRI, true); AI.isValid(); |
| ++AI) |
| Regs.set(*AI); |
| } else if (MO.isRegMask()) { |
| Regs.setBitsNotInMask(MO.getRegMask()); |
| } |
| } |
| } |
| } |
| } |
| |
| void llvm::calculateDbgValueHistory(const MachineFunction *MF, |
| const TargetRegisterInfo *TRI, |
| DbgValueHistoryMap &Result) { |
| BitVector ChangingRegs(TRI->getNumRegs()); |
| collectChangingRegs(MF, TRI, ChangingRegs); |
| |
| const TargetLowering *TLI = MF->getSubtarget().getTargetLowering(); |
| unsigned SP = TLI->getStackPointerRegisterToSaveRestore(); |
| RegDescribedVarsMap RegVars; |
| for (const auto &MBB : *MF) { |
| for (const auto &MI : MBB) { |
| if (!MI.isDebugInstr()) { |
| // Not a DBG_VALUE instruction. It may clobber registers which describe |
| // some variables. |
| for (const MachineOperand &MO : MI.operands()) { |
| if (MO.isReg() && MO.isDef() && MO.getReg()) { |
| // Ignore call instructions that claim to clobber SP. The AArch64 |
| // backend does this for aggregate function arguments. |
| if (MI.isCall() && MO.getReg() == SP) |
| continue; |
| // If this is a virtual register, only clobber it since it doesn't |
| // have aliases. |
| if (TRI->isVirtualRegister(MO.getReg())) |
| clobberRegisterUses(RegVars, MO.getReg(), Result, MI); |
| // If this is a register def operand, it may end a debug value |
| // range. |
| else { |
| for (MCRegAliasIterator AI(MO.getReg(), TRI, true); AI.isValid(); |
| ++AI) |
| if (ChangingRegs.test(*AI)) |
| clobberRegisterUses(RegVars, *AI, Result, MI); |
| } |
| } else if (MO.isRegMask()) { |
| // If this is a register mask operand, clobber all debug values in |
| // non-CSRs. |
| for (unsigned I : ChangingRegs.set_bits()) { |
| // Don't consider SP to be clobbered by register masks. |
| if (unsigned(I) != SP && TRI->isPhysicalRegister(I) && |
| MO.clobbersPhysReg(I)) { |
| clobberRegisterUses(RegVars, I, Result, MI); |
| } |
| } |
| } |
| } |
| continue; |
| } |
| |
| // Skip DBG_LABEL instructions. |
| if (MI.isDebugLabel()) |
| continue; |
| |
| assert(MI.getNumOperands() > 1 && "Invalid DBG_VALUE instruction!"); |
| // Use the base variable (without any DW_OP_piece expressions) |
| // as index into History. The full variables including the |
| // piece expressions are attached to the MI. |
| const DILocalVariable *RawVar = MI.getDebugVariable(); |
| assert(RawVar->isValidLocationForIntrinsic(MI.getDebugLoc()) && |
| "Expected inlined-at fields to agree"); |
| InlinedVariable Var(RawVar, MI.getDebugLoc()->getInlinedAt()); |
| |
| if (unsigned PrevReg = Result.getRegisterForVar(Var)) |
| dropRegDescribedVar(RegVars, PrevReg, Var); |
| |
| Result.startInstrRange(Var, MI); |
| |
| if (unsigned NewReg = isDescribedByReg(MI)) |
| addRegDescribedVar(RegVars, NewReg, Var); |
| } |
| |
| // Make sure locations for register-described variables are valid only |
| // until the end of the basic block (unless it's the last basic block, in |
| // which case let their liveness run off to the end of the function). |
| if (!MBB.empty() && &MBB != &MF->back()) { |
| for (auto I = RegVars.begin(), E = RegVars.end(); I != E;) { |
| auto CurElem = I++; // CurElem can be erased below. |
| if (TRI->isVirtualRegister(CurElem->first) || |
| ChangingRegs.test(CurElem->first)) |
| clobberRegisterUses(RegVars, CurElem, Result, MBB.back()); |
| } |
| } |
| } |
| } |
| |
| #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) |
| LLVM_DUMP_METHOD void DbgValueHistoryMap::dump() const { |
| dbgs() << "DbgValueHistoryMap:\n"; |
| for (const auto &VarRangePair : *this) { |
| const InlinedVariable &Var = VarRangePair.first; |
| const InstrRanges &Ranges = VarRangePair.second; |
| |
| const DILocalVariable *LocalVar = Var.first; |
| const DILocation *Location = Var.second; |
| |
| dbgs() << " - " << LocalVar->getName() << " at "; |
| |
| if (Location) |
| dbgs() << Location->getFilename() << ":" << Location->getLine() << ":" |
| << Location->getColumn(); |
| else |
| dbgs() << "<unknown location>"; |
| |
| dbgs() << " --\n"; |
| |
| for (const InstrRange &Range : Ranges) { |
| dbgs() << " Begin: " << *Range.first; |
| if (Range.second) |
| dbgs() << " End : " << *Range.second; |
| dbgs() << "\n"; |
| } |
| } |
| } |
| #endif |