[InstrProf][Correlator] Do not compress names when reading debug info

[ellis]

Summary

There is no need to compress the names string when correlating with
debug info since InstrProfReader will immediately uncompress it anyway.
This also removes the dependency on zlib in this case.

[kyulee]

LGTM

compiler-rt/test/profile/Darwin/instrprof-debug-info-correlate.c

-// REQUIRES: zlib
-
 // Value profiling is currently not supported in lightweight mode.
 // RUN: %clang_pgogen -o %t -g -mllvm --debug-info-correlate -mllvm --disable-vp=true %S/../Inputs/instrprof-debug-info-correlate-main.cpp %S/../Inputs/instrprof-debug-info-correlate-foo.cpp
 // RUN: env LLVM_PROFILE_FILE=%t.proflite %run %t
 // RUN: llvm-profdata merge -o %t.profdata --debug-info=%t.dSYM %t.proflite
 
 // RUN: %clang_pgogen -o %t.normal -mllvm --disable-vp=true %S/../Inputs/instrprof-debug-info-correlate-main.cpp %S/../Inputs/instrprof-debug-info-correlate-foo.cpp
 // RUN: env LLVM_PROFILE_FILE=%t.profraw %run %t.normal
 // RUN: llvm-profdata merge -o %t.normal.profdata %t.profraw
 
 // RUN: diff %t.normal.profdata %t.profdata

compiler-rt/test/profile/Linux/instrprof-debug-info-correlate.c

-// REQUIRES: zlib
-
 // Value profiling is currently not supported in lightweight mode.
 // RUN: %clang_pgogen -o %t.normal -mllvm --disable-vp=true %S/../Inputs/instrprof-debug-info-correlate-main.cpp %S/../Inputs/instrprof-debug-info-correlate-foo.cpp
 // RUN: env LLVM_PROFILE_FILE=%t.profraw %run %t.normal
 // RUN: llvm-profdata merge -o %t.normal.profdata %t.profraw
 
 // RUN: %clang_pgogen -o %t.d4 -g -gdwarf-4 -mllvm --debug-info-correlate -mllvm --disable-vp=true %S/../Inputs/instrprof-debug-info-correlate-main.cpp %S/../Inputs/instrprof-debug-info-correlate-foo.cpp
 // RUN: env LLVM_PROFILE_FILE=%t.d4.proflite %run %t.d4
 // RUN: llvm-profdata merge -o %t.d4.profdata --debug-info=%t.d4 %t.d4.proflite
 
 // RUN: diff %t.normal.profdata %t.d4.profdata
 
 // RUN: %clang_pgogen -o %t -g -mllvm --debug-info-correlate -mllvm --disable-vp=true %S/../Inputs/instrprof-debug-info-correlate-main.cpp %S/../Inputs/instrprof-debug-info-correlate-foo.cpp
 // RUN: env LLVM_PROFILE_FILE=%t.proflite %run %t
 // RUN: llvm-profdata merge -o %t.profdata --debug-info=%t %t.proflite
 
 // RUN: diff %t.normal.profdata %t.profdata

llvm/include/llvm/ProfileData/InstrProfCorrelator.h

public:
   /// constructs.
   const RawInstrProf::ProfileData<IntPtrT> *getDataPointer() const {
     return Data.empty() ? nullptr : Data.data();
   }
 
   /// Return the number of ProfileData elements.
   size_t getDataSize() const { return Data.size(); }
 
-  /// Return a pointer to the compressed names string that this class
-  /// constructs.
-  const char *getCompressedNamesPointer() const {
-    return CompressedNames.c_str();
-  }
+  /// Return a pointer to the names string that this class constructs.
+  const char *getNamesPointer() const { return Names.c_str(); }
 
-  /// Return the number of bytes in the compressed names string.
-  size_t getCompressedNamesSize() const { return CompressedNames.size(); }
+  /// Return the number of bytes in the names string.
+  size_t getNamesSize() const { return Names.size(); }
 
   static llvm::Expected<std::unique_ptr<InstrProfCorrelatorImpl<IntPtrT>>>
   get(std::unique_ptr<InstrProfCorrelator::Context> Ctx,
       const object::ObjectFile &Obj);
 
 protected:
   std::vector<RawInstrProf::ProfileData<IntPtrT>> Data;
-  std::string CompressedNames;
+  std::string Names;
 
   Error correlateProfileData() override;
   virtual void correlateProfileDataImpl() = 0;
 
   void addProbe(StringRef FunctionName, uint64_t CFGHash, IntPtrT CounterOffset,
                 IntPtrT FunctionPtr, uint32_t NumCounters);
 
 private:
   InstrProfCorrelatorImpl(InstrProfCorrelatorKind Kind,
                           std::unique_ptr<InstrProfCorrelator::Context> Ctx)
       : InstrProfCorrelator(Kind, std::move(Ctx)){};
-  std::vector<std::string> Names;
+  std::vector<std::string> NamesVec;
   llvm::DenseSet<IntPtrT> CounterOffsets;
 
   // Byte-swap the value if necessary.
   template <class T> T maybeSwap(T Value) const {
     return Ctx->ShouldSwapBytes ? sys::getSwappedBytes(Value) : Value;
   }
 };
 
private:
   /// Return the address of the object that the provided DIE symbolizes.
   llvm::Optional<uint64_t> getLocation(const DWARFDie &Die) const;
 
   /// Returns true if the provided DIE symbolizes an instrumentation probe
   /// symbol.
   static bool isDIEOfProbe(const DWARFDie &Die);
 
   /// Iterate over DWARF DIEs to find those that symbolize instrumentation
-  /// probes and construct the ProfileData vector and CompressedNames string.
+  /// probes and construct the ProfileData vector and Names string.
   ///
   /// Here is some example DWARF for an instrumentation probe we are looking
   /// for:
   /// \code
   ///   DW_TAG_subprogram
   ///   DW_AT_low_pc  (0x0000000000000000)
   ///   DW_AT_high_pc (0x0000000000000014)
   ///   DW_AT_name  ("foo")

llvm/lib/ProfileData/InstrProfCorrelator.cpp

if (Obj.isELF() || Obj.isMachO()) {
     return std::make_unique<DwarfInstrProfCorrelator<IntPtrT>>(std::move(DICtx),
                                                                std::move(Ctx));
   }
   return make_error<InstrProfError>(instrprof_error::unsupported_debug_format);
 }
 
 template <class IntPtrT>
 Error InstrProfCorrelatorImpl<IntPtrT>::correlateProfileData() {
-  assert(Data.empty() && CompressedNames.empty() && Names.empty());
+  assert(Data.empty() && Names.empty() && NamesVec.empty());
   correlateProfileDataImpl();
   auto Result =
-      collectPGOFuncNameStrings(Names, /*doCompression=*/true, CompressedNames);
+      collectPGOFuncNameStrings(NamesVec, /*doCompression=*/false, Names);
   CounterOffsets.clear();
-  Names.clear();
+  NamesVec.clear();
   return Result;
 }
 
 template <class IntPtrT>
 void InstrProfCorrelatorImpl<IntPtrT>::addProbe(StringRef FunctionName,
                                                 uint64_t CFGHash,
                                                 IntPtrT CounterOffset,
                                                 IntPtrT FunctionPtr,
                                                 uint32_t NumCounters) {
   // Check if a probe was already added for this counter offset.
   if (!CounterOffsets.insert(CounterOffset).second)
     return;
   Data.push_back({
       maybeSwap<uint64_t>(IndexedInstrProf::ComputeHash(FunctionName)),
       maybeSwap<uint64_t>(CFGHash),
       // In this mode, CounterPtr actually stores the section relative address
       // of the counter.
       maybeSwap<IntPtrT>(CounterOffset),
       maybeSwap<IntPtrT>(FunctionPtr),
       // TODO: Value profiling is not yet supported.
       /*ValuesPtr=*/maybeSwap<IntPtrT>(0),
       maybeSwap<uint32_t>(NumCounters),
       /*NumValueSites=*/{maybeSwap<uint16_t>(0), maybeSwap<uint16_t>(0)},
   });
-  Names.push_back(FunctionName.str());
+  NamesVec.push_back(FunctionName.str());
 }
 
 template <class IntPtrT>
 llvm::Optional<uint64_t>
 DwarfInstrProfCorrelator<IntPtrT>::getLocation(const DWARFDie &Die) const {
   auto Locations = Die.getLocations(dwarf::DW_AT_location);
   if (!Locations) {
     consumeError(Locations.takeError());

llvm/lib/ProfileData/InstrProfReader.cpp

Error RawInstrProfReader<IntPtrT>::readHeader(
 
   if (Correlator) {
     // These sizes in the raw file are zero because we constructed them in the
     // Correlator.
     assert(DataSize == 0 && NamesSize == 0);
     assert(CountersDelta == 0 && NamesDelta == 0);
     Data = Correlator->getDataPointer();
     DataEnd = Data + Correlator->getDataSize();
-    NamesStart = Correlator->getCompressedNamesPointer();
-    NamesEnd = NamesStart + Correlator->getCompressedNamesSize();
+    NamesStart = Correlator->getNamesPointer();
+    NamesEnd = NamesStart + Correlator->getNamesSize();
   } else {
     Data = reinterpret_cast<const RawInstrProf::ProfileData<IntPtrT> *>(
         Start + DataOffset);
     DataEnd = Data + NumData;
     NamesStart = Start + NamesOffset;
     NamesEnd = NamesStart + NamesSize;
   }