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 
18 /// \file LiveDebugValues.cpp
19 ///
20 /// The LiveDebugValues pass extends the range of variable locations
21 /// (specified by DBG_VALUE instructions) from single blocks to successors
22 /// and any other code locations where the variable location is valid.
23 /// There are currently two implementations: the "VarLoc" implementation
24 /// explicitly tracks the location of a variable, while the "InstrRef"
25 /// implementation tracks the values defined by instructions through locations.
26 ///
27 /// This file implements neither; it merely registers the pass, allows the
28 /// user to pick which implementation will be used to propagate variable
29 /// locations.
30 
31 #define DEBUG_TYPE "livedebugvalues"
32 
33 using namespace llvm;
34 
35 /// Generic LiveDebugValues pass. Calls through to VarLocBasedLDV or
36 /// InstrRefBasedLDV to perform location propagation, via the LDVImpl
37 /// base class.
38 class LiveDebugValues : public MachineFunctionPass {
39 public:
40   static char ID;
41 
42   LiveDebugValues();
43   ~LiveDebugValues() { delete TheImpl; }
44 
45   /// Calculate the liveness information for the given machine function.
46   bool runOnMachineFunction(MachineFunction &MF) override;
47 
48   MachineFunctionProperties getRequiredProperties() const override {
49     return MachineFunctionProperties().set(
50         MachineFunctionProperties::Property::NoVRegs);
51   }
52 
53   void getAnalysisUsage(AnalysisUsage &AU) const override {
54     AU.setPreservesCFG();
55     MachineFunctionPass::getAnalysisUsage(AU);
56   }
57 
58 private:
59   LDVImpl *TheImpl;
60 };
61 
62 char LiveDebugValues::ID = 0;
63 
64 char &llvm::LiveDebugValuesID = LiveDebugValues::ID;
65 
66 INITIALIZE_PASS(LiveDebugValues, DEBUG_TYPE, "Live DEBUG_VALUE analysis", false,
67                 false)
68 
69 /// Default construct and initialize the pass.
70 LiveDebugValues::LiveDebugValues() : MachineFunctionPass(ID) {
71   initializeLiveDebugValuesPass(*PassRegistry::getPassRegistry());
72   TheImpl = llvm::makeVarLocBasedLiveDebugValues();
73 }
74 
75 bool LiveDebugValues::runOnMachineFunction(MachineFunction &MF) {
76   auto *TPC = getAnalysisIfAvailable<TargetPassConfig>();
77   return TheImpl->ExtendRanges(MF, TPC);
78 }
79