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 /// Generic LiveDebugValues pass. Calls through to VarLocBasedLDV or
44 /// InstrRefBasedLDV to perform location propagation, via the LDVImpl
45 /// base class.
46 class LiveDebugValues : public MachineFunctionPass {
47 public:
48 static char ID;
49
50 LiveDebugValues();
~LiveDebugValues()51 ~LiveDebugValues() {
52 if (TheImpl)
53 delete TheImpl;
54 }
55
56 /// Calculate the liveness information for the given machine function.
57 bool runOnMachineFunction(MachineFunction &MF) override;
58
getRequiredProperties() const59 MachineFunctionProperties getRequiredProperties() const override {
60 return MachineFunctionProperties().set(
61 MachineFunctionProperties::Property::NoVRegs);
62 }
63
getAnalysisUsage(AnalysisUsage & AU) const64 void getAnalysisUsage(AnalysisUsage &AU) const override {
65 AU.setPreservesCFG();
66 MachineFunctionPass::getAnalysisUsage(AU);
67 }
68
69 private:
70 LDVImpl *TheImpl;
71 TargetPassConfig *TPC;
72 };
73
74 char LiveDebugValues::ID = 0;
75
76 char &llvm::LiveDebugValuesID = LiveDebugValues::ID;
77
78 INITIALIZE_PASS(LiveDebugValues, DEBUG_TYPE, "Live DEBUG_VALUE analysis", false,
79 false)
80
81 /// Default construct and initialize the pass.
LiveDebugValues()82 LiveDebugValues::LiveDebugValues() : MachineFunctionPass(ID) {
83 initializeLiveDebugValuesPass(*PassRegistry::getPassRegistry());
84 TheImpl = nullptr;
85 }
86
runOnMachineFunction(MachineFunction & MF)87 bool LiveDebugValues::runOnMachineFunction(MachineFunction &MF) {
88 if (!TheImpl) {
89 TPC = getAnalysisIfAvailable<TargetPassConfig>();
90
91 bool InstrRefBased = false;
92 if (TPC) {
93 auto &TM = TPC->getTM<TargetMachine>();
94 InstrRefBased = TM.Options.ValueTrackingVariableLocations;
95 }
96
97 // Allow the user to force selection of InstrRef LDV.
98 InstrRefBased |= ForceInstrRefLDV;
99
100 if (InstrRefBased)
101 TheImpl = llvm::makeInstrRefBasedLiveDebugValues();
102 else
103 TheImpl = llvm::makeVarLocBasedLiveDebugValues();
104 }
105
106 return TheImpl->ExtendRanges(MF, TPC);
107 }
108