Using crtp to refactor the xcoff section header

SUMMARY:
According to https://reviews.llvm.org/D68575#inline-617586, Create a NFC patch for it.

Using crtp to refactor the xcoff section header
Move the define of SectionFlagsReservedMask and SectionFlagsTypeMask from XCOFFDumper.cpp to XCOFFObjectFile.h

Reviewers: hubert.reinterpretcast,jasonliu
Subscribers: rupprecht, seiyai,hiraditya

Differential Revision: https://reviews.llvm.org/D69131

3 files changed, 36 insertions, 25 deletions

diff --git a/llvm/include/llvm/Object/XCOFFObjectFile.h b/llvm/include/llvm/Object/XCOFFObjectFile.h
index 84073ce5f6c..4f80297b04c 100644
--- a/llvm/include/llvm/Object/XCOFFObjectFile.h
+++ b/llvm/include/llvm/Object/XCOFFObjectFile.h
@@ -47,7 +47,20 @@ struct XCOFFFileHeader64 {
   support::ubig32_t NumberOfSymTableEntries;
 };
 
-struct XCOFFSectionHeader32 {
+template <typename T> struct XCOFFSectionHeader {
+  // Least significant 3 bits are reserved.
+  static constexpr unsigned SectionFlagsReservedMask = 0x7;
+
+  // The low order 16 bits of section flags denotes the section type.
+  static constexpr unsigned SectionFlagsTypeMask = 0xffffu;
+
+public:
+  StringRef getName() const;
+  uint16_t getSectionType() const;
+  bool isReservedSectionType() const;
+};
+
+struct XCOFFSectionHeader32 : XCOFFSectionHeader<XCOFFSectionHeader32> {
   char Name[XCOFF::NameSize];
   support::ubig32_t PhysicalAddress;
   support::ubig32_t VirtualAddress;
@@ -58,11 +71,9 @@ struct XCOFFSectionHeader32 {
   support::ubig16_t NumberOfRelocations;
   support::ubig16_t NumberOfLineNumbers;
   support::big32_t Flags;
-
-  StringRef getName() const;
 };
 
-struct XCOFFSectionHeader64 {
+struct XCOFFSectionHeader64 : XCOFFSectionHeader<XCOFFSectionHeader64> {
   char Name[XCOFF::NameSize];
   support::ubig64_t PhysicalAddress;
   support::ubig64_t VirtualAddress;
@@ -74,8 +85,6 @@ struct XCOFFSectionHeader64 {
   support::ubig32_t NumberOfLineNumbers;
   support::big32_t Flags;
   char Padding[4];
-
-  StringRef getName() const;
 };
 
 struct XCOFFSymbolEntry {
diff --git a/llvm/lib/Object/XCOFFObjectFile.cpp b/llvm/lib/Object/XCOFFObjectFile.cpp
index 98782c2701c..6f1d999bc20 100644
--- a/llvm/lib/Object/XCOFFObjectFile.cpp
+++ b/llvm/lib/Object/XCOFFObjectFile.cpp
@@ -46,6 +46,25 @@ static StringRef generateXCOFFFixedNameStringRef(const char *Name) {
                     : StringRef(Name, XCOFF::NameSize);
 }
 
+// Explictly instantiate template classes.
+template struct XCOFFSectionHeader<XCOFFSectionHeader32>;
+template struct XCOFFSectionHeader<XCOFFSectionHeader64>;
+
+template <typename T> StringRef XCOFFSectionHeader<T>::getName() const {
+  const T &DerivedXCOFFSectionHeader = static_cast<const T &>(*this);
+  return generateXCOFFFixedNameStringRef(DerivedXCOFFSectionHeader.Name);
+}
+
+template <typename T> uint16_t XCOFFSectionHeader<T>::getSectionType() const {
+  const T &DerivedXCOFFSectionHeader = static_cast<const T &>(*this);
+  return DerivedXCOFFSectionHeader.Flags & SectionFlagsTypeMask;
+}
+
+template <typename T>
+bool XCOFFSectionHeader<T>::isReservedSectionType() const {
+  return getSectionType() & SectionFlagsReservedMask;
+}
+
 bool XCOFFRelocation32::isRelocationSigned() const {
   return Info & XR_SIGN_INDICATOR_MASK;
 }
@@ -688,14 +707,6 @@ ObjectFile::createXCOFFObjectFile(MemoryBufferRef MemBufRef,
   return XCOFFObjectFile::create(FileType, MemBufRef);
 }
 
-StringRef XCOFFSectionHeader32::getName() const {
-  return generateXCOFFFixedNameStringRef(Name);
-}
-
-StringRef XCOFFSectionHeader64::getName() const {
-  return generateXCOFFFixedNameStringRef(Name);
-}
-
 XCOFF::StorageClass XCOFFSymbolRef::getStorageClass() const {
   return OwningObjectPtr->toSymbolEntry(SymEntDataRef)->StorageClass;
 }
diff --git a/llvm/tools/llvm-readobj/XCOFFDumper.cpp b/llvm/tools/llvm-readobj/XCOFFDumper.cpp
index fe95b6d1b49..1f940366559 100644
--- a/llvm/tools/llvm-readobj/XCOFFDumper.cpp
+++ b/llvm/tools/llvm-readobj/XCOFFDumper.cpp
@@ -49,13 +49,6 @@ private:
   void printCsectAuxEnt32(const XCOFFCsectAuxEnt32 *AuxEntPtr);
   void printSectAuxEntForStat(const XCOFFSectAuxEntForStat *AuxEntPtr);
   void printSymbol(const SymbolRef &);
-
-  // Least significant 3 bits are reserved.
-  static constexpr unsigned SectionFlagsReservedMask = 0x7;
-
-  // The low order 16 bits of section flags denotes the section type.
-  static constexpr unsigned SectionFlagsTypeMask = 0xffffu;
-
   void printRelocations(ArrayRef<XCOFFSectionHeader32> Sections);
   const XCOFFObjectFile &Obj;
 };
@@ -496,8 +489,7 @@ void XCOFFDumper::printSectionHeaders(ArrayRef<T> Sections) {
     DictScope SecDS(W, "Section");
 
     W.printNumber("Index", Index++);
-
-    uint16_t SectionType = Sec.Flags & SectionFlagsTypeMask;
+    uint16_t SectionType = Sec.getSectionType();
     switch (SectionType) {
     case XCOFF::STYP_OVRFLO:
       printOverflowSectionHeader(Sec);
@@ -513,8 +505,7 @@ void XCOFFDumper::printSectionHeaders(ArrayRef<T> Sections) {
       printGenericSectionHeader(Sec);
       break;
     }
-    // For now we just dump the section type portion of the flags.
-    if (SectionType & SectionFlagsReservedMask)
+    if (Sec.isReservedSectionType())
       W.printHex("Flags", "Reserved", SectionType);
     else
       W.printEnum("Type", SectionType, makeArrayRef(SectionTypeFlagsNames));