Home | History | Annotate | Line # | Download | only in LiveDebugValues 
      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/Target/TargetMachine.h"
     18 
     19 /// \file LiveDebugValues.cpp
     20 ///
     21 /// The LiveDebugValues pass extends the range of variable locations
     22 /// (specified by DBG_VALUE instructions) from single blocks to successors
     23 /// and any other code locations where the variable location is valid.
     24 /// There are currently two implementations: the "VarLoc" implementation
     25 /// explicitly tracks the location of a variable, while the "InstrRef"
     26 /// implementation tracks the values defined by instructions through locations.
     27 ///
     28 /// This file implements neither; it merely registers the pass, allows the
     29 /// user to pick which implementation will be used to propagate variable
     30 /// locations.
     31 
     32 #define DEBUG_TYPE "livedebugvalues"
     33 
     34 using namespace llvm;
     35 
     36 /// Generic LiveDebugValues pass. Calls through to VarLocBasedLDV or
     37 /// InstrRefBasedLDV to perform location propagation, via the LDVImpl
     38 /// base class.
     39 class LiveDebugValues : public MachineFunctionPass {
     40 public:
     41   static char ID;
     42 
     43   LiveDebugValues();
     44   ~LiveDebugValues() {
     45     if (TheImpl)
     46       delete TheImpl;
     47   }
     48 
     49   /// Calculate the liveness information for the given machine function.
     50   bool runOnMachineFunction(MachineFunction &MF) override;
     51 
     52   MachineFunctionProperties getRequiredProperties() const override {
     53     return MachineFunctionProperties().set(
     54         MachineFunctionProperties::Property::NoVRegs);
     55   }
     56 
     57   void getAnalysisUsage(AnalysisUsage &AU) const override {
     58     AU.setPreservesCFG();
     59     MachineFunctionPass::getAnalysisUsage(AU);
     60   }
     61 
     62 private:
     63   LDVImpl *TheImpl;
     64   TargetPassConfig *TPC;
     65 };
     66 
     67 char LiveDebugValues::ID = 0;
     68 
     69 char &llvm::LiveDebugValuesID = LiveDebugValues::ID;
     70 
     71 INITIALIZE_PASS(LiveDebugValues, DEBUG_TYPE, "Live DEBUG_VALUE analysis", false,
     72                 false)
     73 
     74 /// Default construct and initialize the pass.
     75 LiveDebugValues::LiveDebugValues() : MachineFunctionPass(ID) {
     76   initializeLiveDebugValuesPass(*PassRegistry::getPassRegistry());
     77   TheImpl = nullptr;
     78 }
     79 
     80 bool LiveDebugValues::runOnMachineFunction(MachineFunction &MF) {
     81   if (!TheImpl) {
     82     TPC = getAnalysisIfAvailable<TargetPassConfig>();
     83 
     84     bool InstrRefBased = false;
     85     if (TPC) {
     86       auto &TM = TPC->getTM<TargetMachine>();
     87       InstrRefBased = TM.Options.ValueTrackingVariableLocations;
     88     }
     89 
     90     if (InstrRefBased)
     91       TheImpl = llvm::makeInstrRefBasedLiveDebugValues();
     92     else
     93       TheImpl = llvm::makeVarLocBasedLiveDebugValues();
     94   }
     95 
     96   return TheImpl->ExtendRanges(MF, TPC);
     97 }
     98