tools/llvm-dwp/DWPStringPool.h

   1 #ifndef TOOLS_LLVM_DWP_DWPSTRINGPOOL
   2 #define TOOLS_LLVM_DWP_DWPSTRINGPOOL
   3
   4 #include "llvm/ADT/DenseMap.h"
   5 #include "llvm/MC/MCSection.h"
   6 #include "llvm/MC/MCStreamer.h"
   7 #include <cassert>
   8
   9 namespace llvm {
  10 class DWPStringPool {
  11
  12   struct CStrDenseMapInfo {
  13     static inline const char *getEmptyKey() {
  14       return reinterpret_cast<const char *>(~static_cast<uintptr_t>(0));
  15     }
  16     static inline const char *getTombstoneKey() {
  17       return reinterpret_cast<const char *>(~static_cast<uintptr_t>(1));
  18     }
  19     static unsigned getHashValue(const char *Val) {
  20       assert(Val != getEmptyKey() && "Cannot hash the empty key!");
  21       assert(Val != getTombstoneKey() && "Cannot hash the tombstone key!");
  22       return (unsigned)hash_value(StringRef(Val));
  23     }
  24     static bool isEqual(const char *LHS, const char *RHS) {
  25       if (RHS == getEmptyKey())
  26         return LHS == getEmptyKey();
  27       if (RHS == getTombstoneKey())
  28         return LHS == getTombstoneKey();
  29       return strcmp(LHS, RHS) == 0;
  30     }
  31   };
  32
  33   MCStreamer &Out;
  34   MCSection *Sec;
  35   DenseMap<const char *, uint32_t, CStrDenseMapInfo> Pool;
  36   uint32_t Offset = 0;
  37
  38 public:
  39   DWPStringPool(MCStreamer &Out, MCSection *Sec) : Out(Out), Sec(Sec) {}
  40
  41   uint32_t getOffset(const char *Str, unsigned Length) {
  42     assert(strlen(Str) + 1 == Length && "Ensure length hint is correct");
  43
  44     auto Pair = Pool.insert(std::make_pair(Str, Offset));
  45     if (Pair.second) {
  46       Out.SwitchSection(Sec);
  47       Out.EmitBytes(StringRef(Str, Length));
  48       Offset += Length;
  49     }
  50
  51     return Pair.first->second;
  52   }
  53 };
  54 }
  55
  56 #endif