[NFC][InstrProf]Refactor readPGOFuncNameStrings (#71566)

Refactor this function to take a callback for each decoded string, rename it and change it to a static function in cpp. Move its (sole) caller definition from header to cpp.
- This is a split of patch #66825; to minimize the diff created in a big PR.

Author: mingmingl-llvm

llvm/include/llvm/ProfileData/InstrProf.h

@@ -242,11 +242,6 @@ Error collectGlobalObjectNameStrings(ArrayRef<std::string> NameStrs,
 Error collectPGOFuncNameStrings(ArrayRef<GlobalVariable *> NameVars,
                                 std::string &Result, bool doCompression = true);
 
-/// \c NameStrings is a string composed of one of more sub-strings encoded in
-/// the format described above. The substrings are separated by 0 or more zero
-/// bytes. This method decodes the string and populates the \c Symtab.
-Error readPGOFuncNameStrings(StringRef NameStrings, InstrProfSymtab &Symtab);
-
 /// Check if INSTR_PROF_RAW_VERSION_VAR is defined. This global is only being
 /// set in IR PGO compilation.
 bool isIRPGOFlagSet(const Module *M);
@@ -469,14 +464,14 @@ class InstrProfSymtab {
   /// until before it is used. See also \c create(StringRef) method.
   Error create(object::SectionRef &Section);
 
-  /// This interface is used by reader of CoverageMapping test
-  /// format.
-  inline Error create(StringRef D, uint64_t BaseAddr);
-
   /// \c NameStrings is a string composed of one of more sub-strings
   ///  encoded in the format described in \c collectPGOFuncNameStrings.
   /// This method is a wrapper to \c readPGOFuncNameStrings method.
-  inline Error create(StringRef NameStrings);
+  Error create(StringRef NameStrings);
+
+  /// This interface is used by reader of CoverageMapping test
+  /// format.
+  inline Error create(StringRef D, uint64_t BaseAddr);
 
   /// A wrapper interface to populate the PGO symtab with functions
   /// decls from module \c M. This interface is used by transformation
@@ -547,10 +542,6 @@ Error InstrProfSymtab::create(StringRef D, uint64_t BaseAddr) {
   return Error::success();
 }
 
-Error InstrProfSymtab::create(StringRef NameStrings) {
-  return readPGOFuncNameStrings(NameStrings, *this);
-}
-
 template <typename NameIterRange>
 Error InstrProfSymtab::create(const NameIterRange &IterRange) {
   for (auto Name : IterRange)

llvm/lib/ProfileData/InstrProf.cpp

@@ -458,6 +458,59 @@ Error InstrProfSymtab::create(Module &M, bool InLTO) {
   return Error::success();
 }
 
+/// \c NameStrings is a string composed of one of more possibly encoded
+/// sub-strings. The substrings are separated by 0 or more zero bytes. This
+/// method decodes the string and calls `NameCallback` for each substring.
+static Error
+readAndDecodeStrings(StringRef NameStrings,
+                     std::function<Error(StringRef)> NameCallback) {
+  const uint8_t *P = NameStrings.bytes_begin();
+  const uint8_t *EndP = NameStrings.bytes_end();
+  while (P < EndP) {
+    uint32_t N;
+    uint64_t UncompressedSize = decodeULEB128(P, &N);
+    P += N;
+    uint64_t CompressedSize = decodeULEB128(P, &N);
+    P += N;
+    bool isCompressed = (CompressedSize != 0);
+    SmallVector<uint8_t, 128> UncompressedNameStrings;
+    StringRef NameStrings;
+    if (isCompressed) {
+      if (!llvm::compression::zlib::isAvailable())
+        return make_error<InstrProfError>(instrprof_error::zlib_unavailable);
+
+      if (Error E = compression::zlib::decompress(ArrayRef(P, CompressedSize),
+                                                  UncompressedNameStrings,
+                                                  UncompressedSize)) {
+        consumeError(std::move(E));
+        return make_error<InstrProfError>(instrprof_error::uncompress_failed);
+      }
+      P += CompressedSize;
+      NameStrings = toStringRef(UncompressedNameStrings);
+    } else {
+      NameStrings =
+          StringRef(reinterpret_cast<const char *>(P), UncompressedSize);
+      P += UncompressedSize;
+    }
+    // Now parse the name strings.
+    SmallVector<StringRef, 0> Names;
+    NameStrings.split(Names, getInstrProfNameSeparator());
+    for (StringRef &Name : Names)
+      if (Error E = NameCallback(Name))
+        return E;
+
+    while (P < EndP && *P == 0)
+      P++;
+  }
+  return Error::success();
+}
+
+Error InstrProfSymtab::create(StringRef NameStrings) {
+  return readAndDecodeStrings(
+      NameStrings,
+      std::bind(&InstrProfSymtab::addFuncName, this, std::placeholders::_1));
+}
+
 Error InstrProfSymtab::addFuncWithName(Function &F, StringRef PGOFuncName) {
   if (Error E = addFuncName(PGOFuncName))
     return E;
@@ -566,48 +619,6 @@ Error collectPGOFuncNameStrings(ArrayRef<GlobalVariable *> NameVars,
       NameStrs, compression::zlib::isAvailable() && doCompression, Result);
 }
 
-Error readPGOFuncNameStrings(StringRef NameStrings, InstrProfSymtab &Symtab) {
-  const uint8_t *P = NameStrings.bytes_begin();
-  const uint8_t *EndP = NameStrings.bytes_end();
-  while (P < EndP) {
-    uint32_t N;
-    uint64_t UncompressedSize = decodeULEB128(P, &N);
-    P += N;
-    uint64_t CompressedSize = decodeULEB128(P, &N);
-    P += N;
-    bool isCompressed = (CompressedSize != 0);
-    SmallVector<uint8_t, 128> UncompressedNameStrings;
-    StringRef NameStrings;
-    if (isCompressed) {
-      if (!llvm::compression::zlib::isAvailable())
-        return make_error<InstrProfError>(instrprof_error::zlib_unavailable);
-
-      if (Error E = compression::zlib::decompress(ArrayRef(P, CompressedSize),
-                                                  UncompressedNameStrings,
-                                                  UncompressedSize)) {
-        consumeError(std::move(E));
-        return make_error<InstrProfError>(instrprof_error::uncompress_failed);
-      }
-      P += CompressedSize;
-      NameStrings = toStringRef(UncompressedNameStrings);
-    } else {
-      NameStrings =
-          StringRef(reinterpret_cast<const char *>(P), UncompressedSize);
-      P += UncompressedSize;
-    }
-    // Now parse the name strings.
-    SmallVector<StringRef, 0> Names;
-    NameStrings.split(Names, getInstrProfNameSeparator());
-    for (StringRef &Name : Names)
-      if (Error E = Symtab.addFuncName(Name))
-        return E;
-
-    while (P < EndP && *P == 0)
-      P++;
-  }
-  return Error::success();
-}
-
 void InstrProfRecord::accumulateCounts(CountSumOrPercent &Sum) const {
   uint64_t FuncSum = 0;
   Sum.NumEntries += Counts.size();