[SampleFDO] Extract the code calling each section reader to addOneSection

[wmi]

Summary

This is a followup of https://reviews.llvm.org/D66513. I just realize I should put the code calling each section reader into a separate function (I name it addOneSection), so SampleProfileExtBinaryReader can override it. Otherwise, the base class SampleProfileExtBinaryBaseReader will need to be aware of all different kinds of section readers. That is not right.

[davidxl]

lgtm

llvm/include/llvm/ProfileData/SampleProfReader.h

 /// SampleProfileReaderExtBinaryBase/SampleProfileWriterExtBinaryBase.
 class SampleProfileReaderExtBinaryBase : public SampleProfileReaderBinary {
 protected:
   std::vector<SecHdrTableEntry> SecHdrTable;
   std::error_code readSecHdrTableEntry();
   std::error_code readSecHdrTable();
   virtual std::error_code readHeader() override;
   virtual std::error_code verifySPMagic(uint64_t Magic) override = 0;
+  virtual std::error_code readOneSection(const uint8_t *Start, uint64_t Size,
+                                         SecType Type) = 0;
 
 public:
   SampleProfileReaderExtBinaryBase(std::unique_ptr<MemoryBuffer> B,
                                    LLVMContext &C, SampleProfileFormat Format)
       : SampleProfileReaderBinary(std::move(B), C, Format) {}
 
   /// Read sample profiles in extensible format from the associated file.
   std::error_code read() override;
 };
 
 class SampleProfileReaderExtBinary : public SampleProfileReaderExtBinaryBase {
 private:
   virtual std::error_code verifySPMagic(uint64_t Magic) override;
+  virtual std::error_code readOneSection(const uint8_t *Start, uint64_t Size,
+                                         SecType Type) override;
 
 public:
   SampleProfileReaderExtBinary(std::unique_ptr<MemoryBuffer> B, LLVMContext &C,
                                SampleProfileFormat Format = SPF_Ext_Binary)
       : SampleProfileReaderExtBinaryBase(std::move(B), C, Format) {}
 
   /// \brief Return true if \p Buffer is in the format supported by this class.
   static bool hasFormat(const MemoryBuffer &Buffer);

llvm/lib/ProfileData/SampleProfReader.cpp

std::error_code SampleProfileReaderBinary::read() {
   while (!at_eof()) {
     if (std::error_code EC = readFuncProfile())
       return EC;
   }
 
   return sampleprof_error::success;
 }
 
-std::error_code SampleProfileReaderExtBinaryBase::read() {
-  const uint8_t *BufStart =
-      reinterpret_cast<const uint8_t *>(Buffer->getBufferStart());
-
-  for (auto &Entry : SecHdrTable) {
-    // Skip empty section.
-    if (!Entry.Size)
-      continue;
-    Data = BufStart + Entry.Offset;
-    switch (Entry.Type) {
-    case SecProfSummary:
-      if (std::error_code EC = readSummary())
-        return EC;
-      break;
-    case SecNameTable:
-      if (std::error_code EC = readNameTable())
-        return EC;
-      break;
-    case SecLBRProfile:
-      while (Data < BufStart + Entry.Offset + Entry.Size) {
-        if (std::error_code EC = readFuncProfile())
-          return EC;
-      }
-      break;
-    default:
-      continue;
-    }
-    if (Data != BufStart + Entry.Offset + Entry.Size)
+std::error_code
+SampleProfileReaderExtBinary::readOneSection(const uint8_t *Start,
+                                             uint64_t Size, SecType Type) {
+  Data = Start;
+  switch (Type) {
+    while (Data < Start + Size) {
+    break;
+  return sampleprof_error::success;
+}
+
+std::error_code SampleProfileReaderExtBinaryBase::read() {
+  const uint8_t *BufStart =
+      reinterpret_cast<const uint8_t *>(Buffer->getBufferStart());
+
+  for (auto &Entry : SecHdrTable) {
+    // Skip empty section.
+    if (!Entry.Size)
+      continue;
+    const uint8_t *SecStart = BufStart + Entry.Offset;
+    if (std::error_code EC = readOneSection(SecStart, Entry.Size, Entry.Type))
+      return EC;
+    if (Data != SecStart + Entry.Size)
       return sampleprof_error::malformed;
   }
 
   return sampleprof_error::success;
 }
 
 std::error_code SampleProfileReaderCompactBinary::read() {
   std::vector<uint64_t> OffsetsToUse;