1 //===- LiveDebugValues.cpp - Tracking Debug Value MIs ---------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "LiveDebugValues.h" 10 11 #include "llvm/CodeGen/MachineBasicBlock.h" 12 #include "llvm/CodeGen/MachineFrameInfo.h" 13 #include "llvm/CodeGen/MachineFunctionPass.h" 14 #include "llvm/CodeGen/Passes.h" 15 #include "llvm/InitializePasses.h" 16 #include "llvm/Pass.h" 17 #include "llvm/Support/CommandLine.h" 18 #include "llvm/Target/TargetMachine.h" 19 20 /// \file LiveDebugValues.cpp 21 /// 22 /// The LiveDebugValues pass extends the range of variable locations 23 /// (specified by DBG_VALUE instructions) from single blocks to successors 24 /// and any other code locations where the variable location is valid. 25 /// There are currently two implementations: the "VarLoc" implementation 26 /// explicitly tracks the location of a variable, while the "InstrRef" 27 /// implementation tracks the values defined by instructions through locations. 28 /// 29 /// This file implements neither; it merely registers the pass, allows the 30 /// user to pick which implementation will be used to propagate variable 31 /// locations. 32 33 #define DEBUG_TYPE "livedebugvalues" 34 35 using namespace llvm; 36 37 static cl::opt<bool> 38 ForceInstrRefLDV("force-instr-ref-livedebugvalues", cl::Hidden, 39 cl::desc("Use instruction-ref based LiveDebugValues with " 40 "normal DBG_VALUE inputs"), 41 cl::init(false)); 42 43 // Options to prevent pathological compile-time behavior. If InputBBLimit and 44 // InputDbgValueLimit are both exceeded, range extension is disabled. 45 static cl::opt<unsigned> InputBBLimit( 46 "livedebugvalues-input-bb-limit", 47 cl::desc("Maximum input basic blocks before DBG_VALUE limit applies"), 48 cl::init(10000), cl::Hidden); 49 static cl::opt<unsigned> InputDbgValueLimit( 50 "livedebugvalues-input-dbg-value-limit", 51 cl::desc( 52 "Maximum input DBG_VALUE insts supported by debug range extension"), 53 cl::init(50000), cl::Hidden); 54 55 namespace { 56 /// Generic LiveDebugValues pass. Calls through to VarLocBasedLDV or 57 /// InstrRefBasedLDV to perform location propagation, via the LDVImpl 58 /// base class. 59 class LiveDebugValues : public MachineFunctionPass { 60 public: 61 static char ID; 62 63 LiveDebugValues(); 64 ~LiveDebugValues() {} 65 66 /// Calculate the liveness information for the given machine function. 67 bool runOnMachineFunction(MachineFunction &MF) override; 68 69 MachineFunctionProperties getRequiredProperties() const override { 70 return MachineFunctionProperties().set( 71 MachineFunctionProperties::Property::NoVRegs); 72 } 73 74 void getAnalysisUsage(AnalysisUsage &AU) const override { 75 AU.setPreservesCFG(); 76 MachineFunctionPass::getAnalysisUsage(AU); 77 } 78 79 private: 80 std::unique_ptr<LDVImpl> InstrRefImpl; 81 std::unique_ptr<LDVImpl> VarLocImpl; 82 TargetPassConfig *TPC; 83 MachineDominatorTree MDT; 84 }; 85 } // namespace 86 87 char LiveDebugValues::ID = 0; 88 89 char &llvm::LiveDebugValuesID = LiveDebugValues::ID; 90 91 INITIALIZE_PASS(LiveDebugValues, DEBUG_TYPE, "Live DEBUG_VALUE analysis", false, 92 false) 93 94 /// Default construct and initialize the pass. 95 LiveDebugValues::LiveDebugValues() : MachineFunctionPass(ID) { 96 initializeLiveDebugValuesPass(*PassRegistry::getPassRegistry()); 97 InstrRefImpl = 98 std::unique_ptr<LDVImpl>(llvm::makeInstrRefBasedLiveDebugValues()); 99 VarLocImpl = std::unique_ptr<LDVImpl>(llvm::makeVarLocBasedLiveDebugValues()); 100 } 101 102 bool LiveDebugValues::runOnMachineFunction(MachineFunction &MF) { 103 bool InstrRefBased = MF.useDebugInstrRef(); 104 // Allow the user to force selection of InstrRef LDV. 105 InstrRefBased |= ForceInstrRefLDV; 106 107 TPC = getAnalysisIfAvailable<TargetPassConfig>(); 108 LDVImpl *TheImpl = &*VarLocImpl; 109 110 MachineDominatorTree *DomTree = nullptr; 111 if (InstrRefBased) { 112 DomTree = &MDT; 113 MDT.calculate(MF); 114 TheImpl = &*InstrRefImpl; 115 } 116 117 return TheImpl->ExtendRanges(MF, DomTree, TPC, InputBBLimit, 118 InputDbgValueLimit); 119 } 120