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      1 //===-- LiveStackAnalysis.h - Live Stack Slot Analysis ----------*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file implements the live stack slot analysis pass. It is analogous to
     11 // live interval analysis except it's analyzing liveness of stack slots rather
     12 // than registers.
     13 //
     14 //===----------------------------------------------------------------------===//
     15 
     16 #ifndef LLVM_CODEGEN_LIVESTACKANALYSIS_H
     17 #define LLVM_CODEGEN_LIVESTACKANALYSIS_H
     18 
     19 #include "llvm/CodeGen/LiveInterval.h"
     20 #include "llvm/CodeGen/MachineFunctionPass.h"
     21 #include "llvm/Support/Allocator.h"
     22 #include "llvm/Target/TargetRegisterInfo.h"
     23 #include <map>
     24 #include <unordered_map>
     25 
     26 namespace llvm {
     27 
     28 class LiveStacks : public MachineFunctionPass {
     29   const TargetRegisterInfo *TRI;
     30 
     31   /// Special pool allocator for VNInfo's (LiveInterval val#).
     32   ///
     33   VNInfo::Allocator VNInfoAllocator;
     34 
     35   /// S2IMap - Stack slot indices to live interval mapping.
     36   ///
     37   typedef std::unordered_map<int, LiveInterval> SS2IntervalMap;
     38   SS2IntervalMap S2IMap;
     39 
     40   /// S2RCMap - Stack slot indices to register class mapping.
     41   std::map<int, const TargetRegisterClass *> S2RCMap;
     42 
     43 public:
     44   static char ID; // Pass identification, replacement for typeid
     45   LiveStacks() : MachineFunctionPass(ID) {
     46     initializeLiveStacksPass(*PassRegistry::getPassRegistry());
     47   }
     48 
     49   typedef SS2IntervalMap::iterator iterator;
     50   typedef SS2IntervalMap::const_iterator const_iterator;
     51   const_iterator begin() const { return S2IMap.begin(); }
     52   const_iterator end() const { return S2IMap.end(); }
     53   iterator begin() { return S2IMap.begin(); }
     54   iterator end() { return S2IMap.end(); }
     55 
     56   unsigned getNumIntervals() const { return (unsigned)S2IMap.size(); }
     57 
     58   LiveInterval &getOrCreateInterval(int Slot, const TargetRegisterClass *RC);
     59 
     60   LiveInterval &getInterval(int Slot) {
     61     assert(Slot >= 0 && "Spill slot indice must be >= 0");
     62     SS2IntervalMap::iterator I = S2IMap.find(Slot);
     63     assert(I != S2IMap.end() && "Interval does not exist for stack slot");
     64     return I->second;
     65   }
     66 
     67   const LiveInterval &getInterval(int Slot) const {
     68     assert(Slot >= 0 && "Spill slot indice must be >= 0");
     69     SS2IntervalMap::const_iterator I = S2IMap.find(Slot);
     70     assert(I != S2IMap.end() && "Interval does not exist for stack slot");
     71     return I->second;
     72   }
     73 
     74   bool hasInterval(int Slot) const { return S2IMap.count(Slot); }
     75 
     76   const TargetRegisterClass *getIntervalRegClass(int Slot) const {
     77     assert(Slot >= 0 && "Spill slot indice must be >= 0");
     78     std::map<int, const TargetRegisterClass *>::const_iterator I =
     79         S2RCMap.find(Slot);
     80     assert(I != S2RCMap.end() &&
     81            "Register class info does not exist for stack slot");
     82     return I->second;
     83   }
     84 
     85   VNInfo::Allocator &getVNInfoAllocator() { return VNInfoAllocator; }
     86 
     87   void getAnalysisUsage(AnalysisUsage &AU) const override;
     88   void releaseMemory() override;
     89 
     90   /// runOnMachineFunction - pass entry point
     91   bool runOnMachineFunction(MachineFunction &) override;
     92 
     93   /// print - Implement the dump method.
     94   void print(raw_ostream &O, const Module * = nullptr) const override;
     95 };
     96 }
     97 
     98 #endif /* LLVM_CODEGEN_LIVESTACK_ANALYSIS_H */
     99