165 lines · cpp
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-exception6//7//===----------------------------------------------------------------------===//8 9#include "LiveDebugValues.h"10 11#include "llvm/CodeGen/LiveDebugValuesPass.h"12#include "llvm/CodeGen/MachineDominators.h"13#include "llvm/CodeGen/MachineFunction.h"14#include "llvm/CodeGen/MachineFunctionPass.h"15#include "llvm/CodeGen/Passes.h"16#include "llvm/CodeGen/TargetPassConfig.h"17#include "llvm/InitializePasses.h"18#include "llvm/Pass.h"19#include "llvm/PassRegistry.h"20#include "llvm/Support/CommandLine.h"21#include "llvm/Target/TargetMachine.h"22#include "llvm/TargetParser/Triple.h"23 24/// \file LiveDebugValues.cpp25///26/// The LiveDebugValues pass extends the range of variable locations27/// (specified by DBG_VALUE instructions) from single blocks to successors28/// and any other code locations where the variable location is valid.29/// There are currently two implementations: the "VarLoc" implementation30/// explicitly tracks the location of a variable, while the "InstrRef"31/// implementation tracks the values defined by instructions through locations.32///33/// This file implements neither; it merely registers the pass, allows the34/// user to pick which implementation will be used to propagate variable35/// locations.36 37#define DEBUG_TYPE "livedebugvalues"38 39using namespace llvm;40 41static cl::opt<bool>42 ForceInstrRefLDV("force-instr-ref-livedebugvalues", cl::Hidden,43 cl::desc("Use instruction-ref based LiveDebugValues with "44 "normal DBG_VALUE inputs"),45 cl::init(false));46 47static cl::opt<cl::boolOrDefault> ValueTrackingVariableLocations(48 "experimental-debug-variable-locations",49 cl::desc("Use experimental new value-tracking variable locations"));50 51// Options to prevent pathological compile-time behavior. If InputBBLimit and52// InputDbgValueLimit are both exceeded, range extension is disabled.53static cl::opt<unsigned> InputBBLimit(54 "livedebugvalues-input-bb-limit",55 cl::desc("Maximum input basic blocks before DBG_VALUE limit applies"),56 cl::init(10000), cl::Hidden);57static cl::opt<unsigned> InputDbgValueLimit(58 "livedebugvalues-input-dbg-value-limit",59 cl::desc(60 "Maximum input DBG_VALUE insts supported by debug range extension"),61 cl::init(50000), cl::Hidden);62 63namespace {64/// Generic LiveDebugValues pass. Calls through to VarLocBasedLDV or65/// InstrRefBasedLDV to perform location propagation, via the LDVImpl66/// base class.67class LiveDebugValuesLegacy : public MachineFunctionPass {68public:69 static char ID;70 71 LiveDebugValuesLegacy();72 ~LiveDebugValuesLegacy() override = default;73 74 /// Calculate the liveness information for the given machine function.75 bool runOnMachineFunction(MachineFunction &MF) override;76 77 void getAnalysisUsage(AnalysisUsage &AU) const override {78 AU.setPreservesCFG();79 AU.addRequired<TargetPassConfig>();80 MachineFunctionPass::getAnalysisUsage(AU);81 }82};83 84struct LiveDebugValues {85 LiveDebugValues();86 ~LiveDebugValues() = default;87 bool run(MachineFunction &MF, bool ShouldEmitDebugEntryValues);88 89private:90 std::unique_ptr<LDVImpl> InstrRefImpl;91 std::unique_ptr<LDVImpl> VarLocImpl;92 MachineDominatorTree MDT;93};94} // namespace95 96char LiveDebugValuesLegacy::ID = 0;97 98char &llvm::LiveDebugValuesID = LiveDebugValuesLegacy::ID;99 100INITIALIZE_PASS(LiveDebugValuesLegacy, DEBUG_TYPE, "Live DEBUG_VALUE analysis",101 false, false)102 103/// Default construct and initialize the pass.104LiveDebugValuesLegacy::LiveDebugValuesLegacy() : MachineFunctionPass(ID) {105 initializeLiveDebugValuesLegacyPass(*PassRegistry::getPassRegistry());106}107 108LiveDebugValues::LiveDebugValues() {109 InstrRefImpl =110 std::unique_ptr<LDVImpl>(llvm::makeInstrRefBasedLiveDebugValues());111 VarLocImpl = std::unique_ptr<LDVImpl>(llvm::makeVarLocBasedLiveDebugValues());112}113 114PreservedAnalyses115LiveDebugValuesPass::run(MachineFunction &MF,116 MachineFunctionAnalysisManager &MFAM) {117 if (!LiveDebugValues().run(MF, ShouldEmitDebugEntryValues))118 return PreservedAnalyses::all();119 auto PA = getMachineFunctionPassPreservedAnalyses();120 PA.preserveSet<CFGAnalyses>();121 return PA;122}123 124void LiveDebugValuesPass::printPipeline(125 raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {126 OS << MapClassName2PassName(name());127 if (ShouldEmitDebugEntryValues)128 OS << "<emit-debug-entry-values>";129}130 131bool LiveDebugValuesLegacy::runOnMachineFunction(MachineFunction &MF) {132 auto *TPC = &getAnalysis<TargetPassConfig>();133 return LiveDebugValues().run(134 MF, TPC->getTM<TargetMachine>().Options.ShouldEmitDebugEntryValues());135}136 137bool LiveDebugValues::run(MachineFunction &MF,138 bool ShouldEmitDebugEntryValues) {139 bool InstrRefBased = MF.useDebugInstrRef();140 // Allow the user to force selection of InstrRef LDV.141 InstrRefBased |= ForceInstrRefLDV;142 143 LDVImpl *TheImpl = &*VarLocImpl;144 145 MachineDominatorTree *DomTree = nullptr;146 if (InstrRefBased) {147 DomTree = &MDT;148 MDT.recalculate(MF);149 TheImpl = &*InstrRefImpl;150 }151 152 return TheImpl->ExtendRanges(MF, DomTree, ShouldEmitDebugEntryValues,153 InputBBLimit, InputDbgValueLimit);154}155 156bool llvm::debuginfoShouldUseDebugInstrRef(const Triple &T) {157 // Enable by default on x86_64, disable if explicitly turned off on cmdline.158 if (T.getArch() == llvm::Triple::x86_64 &&159 ValueTrackingVariableLocations != cl::boolOrDefault::BOU_FALSE)160 return true;161 162 // Enable if explicitly requested on command line.163 return ValueTrackingVariableLocations == cl::boolOrDefault::BOU_TRUE;164}165