llvm/DWP/DWPStringPool.h

0001 #ifndef LLVM_DWP_DWPSTRINGPOOL_H
0002 #define LLVM_DWP_DWPSTRINGPOOL_H
0003
0004 #include "llvm/ADT/DenseMap.h"
0005 #include "llvm/MC/MCSection.h"
0006 #include "llvm/MC/MCStreamer.h"
0007 #include <cassert>
0008
0009 namespace llvm {
0010 class DWPStringPool {
0011
0012   struct CStrDenseMapInfo {
0013     static inline const char *getEmptyKey() {
0014       return reinterpret_cast<const char *>(~static_cast<uintptr_t>(0));
0015     }
0016     static inline const char *getTombstoneKey() {
0017       return reinterpret_cast<const char *>(~static_cast<uintptr_t>(1));
0018     }
0019     static unsigned getHashValue(const char *Val) {
0020       assert(Val != getEmptyKey() && "Cannot hash the empty key!");
0021       assert(Val != getTombstoneKey() && "Cannot hash the tombstone key!");
0022       return (unsigned)hash_value(StringRef(Val));
0023     }
0024     static bool isEqual(const char *LHS, const char *RHS) {
0025       if (RHS == getEmptyKey())
0026         return LHS == getEmptyKey();
0027       if (RHS == getTombstoneKey())
0028         return LHS == getTombstoneKey();
0029       return strcmp(LHS, RHS) == 0;
0030     }
0031   };
0032
0033   MCStreamer &Out;
0034   MCSection *Sec;
0035   DenseMap<const char *, uint32_t, CStrDenseMapInfo> Pool;
0036   uint32_t Offset = 0;
0037
0038 public:
0039   DWPStringPool(MCStreamer &Out, MCSection *Sec) : Out(Out), Sec(Sec) {}
0040
0041   uint32_t getOffset(const char *Str, unsigned Length) {
0042     assert(strlen(Str) + 1 == Length && "Ensure length hint is correct");
0043
0044     auto Pair = Pool.insert(std::make_pair(Str, Offset));
0045     if (Pair.second) {
0046       Out.switchSection(Sec);
0047       Out.emitBytes(StringRef(Str, Length));
0048       Offset += Length;
0049     }
0050
0051     return Pair.first->second;
0052   }
0053 };
0054 } // namespace llvm
0055
0056 #endif // LLVM_DWP_DWPSTRINGPOOL_H