[llvm] r259941 - [PGO] Speed up name tab reading

[Sean Silva via llvm-commits]

On Fri, Feb 5, 2016 at 2:32 PM, Xinliang David Li via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: davidxl
> Date: Fri Feb  5 16:32:01 2016
> New Revision: 259941
>
> URL: http://llvm.org/viewvc/llvm-project?rev=259941&view=rev
> Log:
> [PGO] Speed up name tab reading
>  The change allows skipping duplicate strings
>  early to avoid redundant md5 computation and
>  string copying/swapping.
>
>
>
>
> Modified:
>     llvm/trunk/include/llvm/ProfileData/InstrProf.h
>
> Modified: llvm/trunk/include/llvm/ProfileData/InstrProf.h
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ProfileData/InstrProf.h?rev=259941&r1=259940&r2=259941&view=diff
>
> ==============================================================================
> --- llvm/trunk/include/llvm/ProfileData/InstrProf.h (original)
> +++ llvm/trunk/include/llvm/ProfileData/InstrProf.h Fri Feb  5 16:32:01
> 2016
> @@ -269,17 +269,20 @@ public:
>  private:
>    StringRef Data;
>    uint64_t Address;
> -  // A map from MD5 hash keys to function name strings.
> -  std::vector<std::pair<uint64_t, std::string>> HashNameMap;
> +  // Unique name strings.
> +  StringSet<> NameTab;
> +  // A map from MD5 keys to function name strings.
> +  std::vector<std::pair<uint64_t, StringRef>> MD5NameMap;
>    // A map from function runtime address to function name MD5 hash.
>    // This map is only populated and used by raw instr profile reader.
>    AddrHashMap AddrToMD5Map;
>
>  public:
> -  InstrProfSymtab() : Data(), Address(0), HashNameMap(), AddrToMD5Map() {}
> +  InstrProfSymtab()
> +      : Data(), Address(0), NameTab(), MD5NameMap(), AddrToMD5Map() {}
>
>    /// Create InstrProfSymtab from an object file section which
> -  /// contains function PGO names. When section may contain raw
> +  /// contains function PGO names. When section may contain raw
>    /// string data or string data in compressed form. This method
>    /// only initialize the symtab with reference to the data and
>    /// the section base address. The decompression will be delayed
> @@ -307,8 +310,10 @@ public:
>    /// Update the symtab by adding \p FuncName to the table. This interface
>    /// is used by the raw and text profile readers.
>    void addFuncName(StringRef FuncName) {
> -    HashNameMap.push_back(std::make_pair(
> -        IndexedInstrProf::ComputeHash(FuncName), FuncName.str()));
> +    auto ins = NameTab.insert(FuncName);
>

http://llvm.org/docs/CodingStandards.html#name-types-functions-variables-and-enumerators-properly

-- Sean Silva


> +    if (ins.second)
> +      MD5NameMap.push_back(std::make_pair(
> +          IndexedInstrProf::ComputeHash(FuncName), ins.first->getKey()));
>    }
>    /// Map a function address to its name's MD5 hash. This interface
>    /// is only used by the raw profiler reader.
> @@ -346,15 +351,13 @@ std::error_code InstrProfSymtab::create(
>  template <typename NameIterRange>
>  void InstrProfSymtab::create(const NameIterRange &IterRange) {
>    for (auto Name : IterRange)
> -    HashNameMap.push_back(
> -        std::make_pair(IndexedInstrProf::ComputeHash(Name), Name.str()));
> +    addFuncName(Name);
> +
>    finalizeSymtab();
>  }
>
>  void InstrProfSymtab::finalizeSymtab() {
> -  std::sort(HashNameMap.begin(), HashNameMap.end(), less_first());
> -  HashNameMap.erase(std::unique(HashNameMap.begin(), HashNameMap.end()),
> -                    HashNameMap.end());
> +  std::sort(MD5NameMap.begin(), MD5NameMap.end(), less_first());
>    std::sort(AddrToMD5Map.begin(), AddrToMD5Map.end(), less_first());
>    AddrToMD5Map.erase(std::unique(AddrToMD5Map.begin(),
> AddrToMD5Map.end()),
>                       AddrToMD5Map.end());
> @@ -362,10 +365,10 @@ void InstrProfSymtab::finalizeSymtab() {
>
>  StringRef InstrProfSymtab::getFuncName(uint64_t FuncMD5Hash) {
>    auto Result =
> -      std::lower_bound(HashNameMap.begin(), HashNameMap.end(),
> FuncMD5Hash,
> +      std::lower_bound(MD5NameMap.begin(), MD5NameMap.end(), FuncMD5Hash,
>                         [](const std::pair<uint64_t, std::string> &LHS,
>                            uint64_t RHS) { return LHS.first < RHS; });
> -  if (Result != HashNameMap.end())
> +  if (Result != MD5NameMap.end())
>      return Result->second;
>    return StringRef();
>  }
>
>
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