[XCOFF] Support the subtype in Dwarf section headers

llvm/include/llvm/Object/XCOFFObjectFile.h

@@ -153,15 +153,19 @@ struct XCOFFAuxiliaryHeader64 : XCOFFAuxiliaryHeader<XCOFFAuxiliaryHeader64> {
 };
 
 template <typename T> struct XCOFFSectionHeader {
-  // Least significant 3 bits are reserved.
+  // The section flags definitions are the same in both 32- and 64-bit objects.
+  //  Least significant 3 bits are reserved.
   static constexpr unsigned SectionFlagsReservedMask = 0x7;
 
   // The low order 16 bits of section flags denotes the section type.
+  // The high order 16 bits of section flags denotes the section subtype.
+  // For now, this is only used for DWARF sections.
   static constexpr unsigned SectionFlagsTypeMask = 0xffffu;
 
 public:
   StringRef getName() const;
   uint16_t getSectionType() const;
+  uint32_t getSectionSubtype() const;
   bool isReservedSectionType() const;
 };
 

llvm/include/llvm/ObjectYAML/XCOFFYAML.h

@@ -79,6 +79,7 @@ struct Section {
   llvm::yaml::Hex16 NumberOfRelocations;
   llvm::yaml::Hex16 NumberOfLineNumbers; // Line number counts. Not supported yet.
   uint32_t Flags;
+  std::optional<XCOFF::DwarfSectionSubtypeFlags> SectionSubtype;
   yaml::BinaryRef SectionData;
   std::vector<Relocation> Relocations;
 };
@@ -232,6 +233,10 @@ template <> struct ScalarBitSetTraits<XCOFF::SectionTypeFlags> {
   static void bitset(IO &IO, XCOFF::SectionTypeFlags &Value);
 };
 
+template <> struct ScalarEnumerationTraits<XCOFF::DwarfSectionSubtypeFlags> {
+  static void enumeration(IO &IO, XCOFF::DwarfSectionSubtypeFlags &Value);
+};
+
 template <> struct ScalarEnumerationTraits<XCOFF::StorageClass> {
   static void enumeration(IO &IO, XCOFF::StorageClass &Value);
 };

llvm/lib/Object/XCOFFObjectFile.cpp

@@ -64,6 +64,12 @@ template <typename T> uint16_t XCOFFSectionHeader<T>::getSectionType() const {
   return DerivedXCOFFSectionHeader.Flags & SectionFlagsTypeMask;
 }
 
+template <typename T>
+uint32_t XCOFFSectionHeader<T>::getSectionSubtype() const {
+  const T &DerivedXCOFFSectionHeader = static_cast<const T &>(*this);
+  return DerivedXCOFFSectionHeader.Flags & ~SectionFlagsTypeMask;
+}
+
 template <typename T>
 bool XCOFFSectionHeader<T>::isReservedSectionType() const {
   return getSectionType() & SectionFlagsReservedMask;

llvm/lib/ObjectYAML/XCOFFEmitter.cpp

@@ -210,6 +210,21 @@ bool XCOFFWriter::initSectionHeaders(uint64_t &CurrentOffset) {
         return false;
       }
     }
+    if (InitSections[I].SectionSubtype) {
+      uint32_t DWARFSubtype =
+          static_cast<uint32_t>(*InitSections[I].SectionSubtype);
+      if (InitSections[I].Flags != XCOFF::STYP_DWARF) {
+        ErrHandler("a DWARFSectionSubtype is only allowed for a DWARF section");
+        return false;
+      }
+      unsigned Mask = Is64Bit ? XCOFFSectionHeader64::SectionFlagsTypeMask
+                              : XCOFFSectionHeader32::SectionFlagsTypeMask;
+      if (DWARFSubtype & Mask) {
+        ErrHandler("the low-order bits of DWARFSectionSubtype must be 0");
+        return false;
+      }
+      InitSections[I].Flags |= DWARFSubtype;
+    }
   }
   return initRelocations(CurrentOffset);
 }

llvm/lib/ObjectYAML/XCOFFYAML.cpp

@@ -44,6 +44,24 @@ void ScalarBitSetTraits<XCOFF::SectionTypeFlags>::bitset(
 #undef ECase
 }
 
+void ScalarEnumerationTraits<XCOFF::DwarfSectionSubtypeFlags>::enumeration(
+    IO &IO, XCOFF::DwarfSectionSubtypeFlags &Value) {
+#define ECase(X) IO.enumCase(Value, #X, XCOFF::X)
+  ECase(SSUBTYP_DWINFO);
+  ECase(SSUBTYP_DWLINE);
+  ECase(SSUBTYP_DWPBNMS);
+  ECase(SSUBTYP_DWPBTYP);
+  ECase(SSUBTYP_DWARNGE);
+  ECase(SSUBTYP_DWABREV);
+  ECase(SSUBTYP_DWSTR);
+  ECase(SSUBTYP_DWRNGES);
+  ECase(SSUBTYP_DWLOC);
+  ECase(SSUBTYP_DWFRAME);
+  ECase(SSUBTYP_DWMAC);
+#undef ECase
+  IO.enumFallback<Hex32>(Value);
+}
+
 void ScalarEnumerationTraits<XCOFF::StorageClass>::enumeration(
     IO &IO, XCOFF::StorageClass &Value) {
 #define ECase(X) IO.enumCase(Value, #X, XCOFF::X)
@@ -232,6 +250,7 @@ void MappingTraits<XCOFFYAML::Section>::mapping(IO &IO,
   IO.mapOptional("NumberOfRelocations", Sec.NumberOfRelocations);
   IO.mapOptional("NumberOfLineNumbers", Sec.NumberOfLineNumbers);
   IO.mapOptional("Flags", NC->Flags);
+  IO.mapOptional("DWARFSectionSubtype", Sec.SectionSubtype);
   IO.mapOptional("SectionData", Sec.SectionData);
   IO.mapOptional("Relocations", Sec.Relocations);
 }

llvm/test/CodeGen/PowerPC/aix-dwarf.ll

@@ -84,6 +84,7 @@ entry:
 ; SEC-NEXT:      NumberOfRelocations: 0
 ; SEC-NEXT:      NumberOfLineNumbers: 0
 ; SEC-NEXT:      Type: STYP_DWARF (0x10)
+; SEC-NEXT:      DWARFSubType: SSUBTYP_DWABREV (0x60000)
 ; SEC-NEXT:    }
 ; SEC-NEXT:    Section {
 ; SEC-NEXT:      Index: 4
@@ -100,6 +101,7 @@ entry:
 ; SEC-NEXT:      NumberOfRelocations: 4
 ; SEC-NEXT:      NumberOfLineNumbers: 0
 ; SEC-NEXT:      Type: STYP_DWARF (0x10)
+; SEC-NEXT:      DWARFSubType: SSUBTYP_DWINFO (0x10000)
 ; SEC-NEXT:    }
 ; SEC-NEXT:    Section {
 ; SEC-NEXT:      Index: 5
@@ -116,6 +118,7 @@ entry:
 ; SEC-NEXT:      NumberOfRelocations: 1
 ; SEC-NEXT:      NumberOfLineNumbers: 0
 ; SEC-NEXT:      Type: STYP_DWARF (0x10)
+; SEC-NEXT:      DWARFSubType: SSUBTYP_DWLINE (0x20000)
 ; SEC-NEXT:    }
 ; SEC-NEXT:  ]
 

llvm/test/tools/llvm-readobj/XCOFF/sections.test

@@ -2,39 +2,61 @@
 
 # RUN: yaml2obj %s -o %t1
 # RUN: llvm-readobj --section-headers %t1 | \
-# RUN:   FileCheck --strict-whitespace --match-full-lines --check-prefix=SEC32 %s
+# RUN:   FileCheck --strict-whitespace --match-full-lines --check-prefixes=SEC,SEC32 %s
+
+# RUN: yaml2obj -DMAGIC=0x01F7 %s -o %t2
+# RUN: llvm-readobj --section-headers %t2 | \
+# RUN:   FileCheck --strict-whitespace --match-full-lines --check-prefixes=SEC,SEC64 %s
 
 #      SEC32:Format: aixcoff-rs6000
+#      SEC64:Format: aix5coff64-rs6000
 # SEC32-NEXT:Arch: powerpc
+# SEC64-NEXT:Arch: powerpc64
 # SEC32-NEXT:AddressSize: 32bit
-# SEC32-NEXT:Sections [
-# SEC32-NEXT:  Section {
-# SEC32-NEXT:    Index: 1
-# SEC32-NEXT:    Name: .text
-# SEC32-NEXT:    PhysicalAddress: 0x0
-# SEC32-NEXT:    VirtualAddress: 0x0
-# SEC32-NEXT:    Size: 0x2
-# SEC32-NEXT:    RawDataOffset: 0x64
-# SEC32-NEXT:    RelocationPointer: 0x0
-# SEC32-NEXT:    LineNumberPointer: 0x0
-# SEC32-NEXT:    NumberOfRelocations: 0
-# SEC32-NEXT:    NumberOfLineNumbers: 0
-# SEC32-NEXT:    Type: STYP_TEXT (0x20)
-# SEC32-NEXT:  }
-# SEC32-NEXT:  Section {
-# SEC32-NEXT:    Index: 2
-# SEC32-NEXT:    Name: .data
-# SEC32-NEXT:    PhysicalAddress: 0x0
-# SEC32-NEXT:    VirtualAddress: 0x0
-# SEC32-NEXT:    Size: 0x2
-# SEC32-NEXT:    RawDataOffset: 0x68
-# SEC32-NEXT:    RelocationPointer: 0x6A
-# SEC32-NEXT:    LineNumberPointer: 0x0
-# SEC32-NEXT:    NumberOfRelocations: 1
-# SEC32-NEXT:    NumberOfLineNumbers: 0
-# SEC32-NEXT:    Type: STYP_DATA (0x40)
-# SEC32-NEXT:  }
-# SEC32-NEXT:]
+# SEC64-NEXT:AddressSize: 64bit
+#   SEC-NEXT:Sections [
+#   SEC-NEXT:  Section {
+#   SEC-NEXT:    Index: 1
+#   SEC-NEXT:    Name: .text
+#   SEC-NEXT:    PhysicalAddress: 0x0
+#   SEC-NEXT:    VirtualAddress: 0x0
+#   SEC-NEXT:    Size: 0x2
+# SEC32-NEXT:    RawDataOffset: 0xB4
+# SEC64-NEXT:    RawDataOffset: 0x138
+#   SEC-NEXT:    RelocationPointer: 0x0
+#   SEC-NEXT:    LineNumberPointer: 0x0
+#   SEC-NEXT:    NumberOfRelocations: 0
+#   SEC-NEXT:    NumberOfLineNumbers: 0
+#   SEC-NEXT:    Type: STYP_TEXT (0x20)
+#   SEC-NEXT:  }
+#   SEC-NEXT:  Section {
+#   SEC-NEXT:    Index: 2
+#   SEC-NEXT:    Name: .data
+#   SEC-NEXT:    PhysicalAddress: 0x0
+#   SEC-NEXT:    VirtualAddress: 0x0
+#   SEC-NEXT:    Size: 0x2
+# SEC32-NEXT:    RawDataOffset: 0xB8
+# SEC64-NEXT:    RawDataOffset: 0x13C
+# SEC32-NEXT:    RelocationPointer: 0xC4
+# SEC64-NEXT:    RelocationPointer: 0x148
+#   SEC-NEXT:    LineNumberPointer: 0x0
+#   SEC-NEXT:    NumberOfRelocations: 1
+#   SEC-NEXT:    NumberOfLineNumbers: 0
+#   SEC-NEXT:    Type: STYP_DATA (0x40)
+#   SEC-NEXT:  }
+#   SEC-NEXT:  Section {
+#   SEC-NEXT:    Index: 3
+#   SEC-NEXT:    Name: .dwabrev
+#        SEC:    Type: STYP_DWARF (0x10)
+#   SEC-NEXT:    DWARFSubType: SSUBTYP_DWABREV (0x60000)
+#   SEC-NEXT:  }
+#   SEC-NEXT:  Section {
+#   SEC-NEXT:    Index: 4
+#   SEC-NEXT:    Name: .dwinfo
+#        SEC:    Type: STYP_DWARF (0x10)
+#   SEC-NEXT:    DWARFSubType: SSUBTYP_DWINFO (0x10000)
+#   SEC-NEXT:  }
+#   SEC-NEXT:]
 
 --- !XCOFF
 FileHeader:
@@ -51,39 +73,15 @@ Sections:
         Symbol:  0x21
         Info:    0x1F
         Type:    0x0
-
-# RUN: yaml2obj -DMAGIC=0x01F7 %s -o %t2
-# RUN: llvm-readobj --section-headers %t2 | \
-# RUN:   FileCheck --strict-whitespace --match-full-lines --check-prefix=SEC64 %s
-
-#      SEC64:Format: aix5coff64-rs6000
-# SEC64-NEXT:Arch: powerpc64
-# SEC64-NEXT:AddressSize: 64bit
-# SEC64-NEXT:Sections [
-# SEC64-NEXT:  Section {
-# SEC64-NEXT:    Index: 1
-# SEC64-NEXT:    Name: .text
-# SEC64-NEXT:    PhysicalAddress: 0x0
-# SEC64-NEXT:    VirtualAddress: 0x0
-# SEC64-NEXT:    Size: 0x2
-# SEC64-NEXT:    RawDataOffset: 0xA8
-# SEC64-NEXT:    RelocationPointer: 0x0
-# SEC64-NEXT:    LineNumberPointer: 0x0
-# SEC64-NEXT:    NumberOfRelocations: 0
-# SEC64-NEXT:    NumberOfLineNumbers: 0
-# SEC64-NEXT:    Type: STYP_TEXT (0x20)
-# SEC64-NEXT:  }
-# SEC64-NEXT:  Section {
-# SEC64-NEXT:    Index: 2
-# SEC64-NEXT:    Name: .data
-# SEC64-NEXT:    PhysicalAddress: 0x0
-# SEC64-NEXT:    VirtualAddress: 0x0
-# SEC64-NEXT:    Size: 0x2
-# SEC64-NEXT:    RawDataOffset: 0xAC
-# SEC64-NEXT:    RelocationPointer: 0xAE
-# SEC64-NEXT:    LineNumberPointer: 0x0
-# SEC64-NEXT:    NumberOfRelocations: 1
-# SEC64-NEXT:    NumberOfLineNumbers: 0
-# SEC64-NEXT:    Type: STYP_DATA (0x40)
-# SEC64-NEXT:  }
-# SEC64-NEXT:]
+  - Name:            .dwabrev
+    Address:         0x0
+    Size:            0x4
+    Flags:           [ STYP_DWARF ]
+    DWARFSectionSubtype: SSUBTYP_DWABREV
+    SectionData:     01110125
+  - Name:            .dwinfo
+    Address:         0x0
+    Size:            0x4
+    Flags:           [ STYP_DWARF ]
+    DWARFSectionSubtype: SSUBTYP_DWINFO
+    SectionData:     00000080

llvm/test/tools/yaml2obj/XCOFF/dwarf-subsection-types.yaml

@@ -0,0 +1,105 @@
+## Test that we can generate and read DWARF section headers.
+
+# RUN: yaml2obj --docnum=1 %s -o %t32
+# RUN: obj2yaml %t32 | FileCheck --check-prefix=YAML %s
+
+# RUN: yaml2obj --docnum=1 -DMAGIC=0x01F7 %s -o %t64
+# RUN: obj2yaml %t64 | FileCheck --check-prefix=YAML %s
+
+# YAML:         - Name:            .dwabrev
+# YAML:         Flags:           [ STYP_DWARF ]
+# YAML-NEXT:    DWARFSectionSubtype: SSUBTYP_DWABREV
+# YAML:         - Name:            .dwinfo
+# YAML:         Flags:           [ STYP_DWARF ]
+# YAML-NEXT:    DWARFSectionSubtype: SSUBTYP_DWINFO
+# YAML:         - Name:            .dwline
+# YAML:         Flags:           [ STYP_DWARF ]
+# YAML-NEXT:    DWARFSectionSubtype: SSUBTYP_DWLINE
+
+--- !XCOFF
+FileHeader:
+  MagicNumber: [[MAGIC=0x01DF]]
+  NumberOfSections: 4
+  CreationTime:    0
+  AuxiliaryHeaderSize: 0
+  Flags:           0x0
+Sections:
+  - Name:            .data
+    Address:         0x0
+    Size:            0x4
+    Flags:           [ STYP_DATA ]
+    SectionData:     '00000001'
+  - Name:            .dwabrev
+    Address:         0x0
+    Size:            0x4
+    Flags:           [ STYP_DWARF ]
+    DWARFSectionSubtype: SSUBTYP_DWABREV
+    SectionData:     01110125
+  - Name:            .dwinfo
+    Address:         0x0
+    Size:            0x4
+    Flags:           [ STYP_DWARF ]
+    DWARFSectionSubtype: SSUBTYP_DWINFO
+    SectionData:     00000080
+  - Name:            .dwline
+    Address:         0x0
+    Size:            0x4
+    Flags:           [ STYP_DWARF ]
+    DWARFSectionSubtype: SSUBTYP_DWLINE
+    SectionData:     00000021
+StringTable:     {}
+...
+
+## Test that an invalid DWARF section subtype is diagnosed.
+# RUN: not yaml2obj --docnum=2 %s -o %t 2>&1 | FileCheck --check-prefix=ERR1 %s
+
+# ERR1: the low-order bits of DWARFSectionSubtype must be 0
+
+--- !XCOFF
+FileHeader:
+  MagicNumber: 0x01DF
+  NumberOfSections: 2
+  CreationTime:    0
+  AuxiliaryHeaderSize: 0
+  Flags:           0x0
+Sections:
+  - Name:            .data
+    Address:         0x0
+    Size:            0x4
+    Flags:           [ STYP_DATA ]
+    SectionData:     '00000001'
+  - Name:            .dwabrev
+    Address:         0x0
+    Size:            0x4
+    Flags:           [ STYP_DWARF ]
+    DWARFSectionSubtype: 0x12345
+    SectionData:     01110125
+StringTable:     {}
+...
+
+## Test that a DWARF section subtype on a non-DWARF section is diagnosed.
+# RUN: not yaml2obj --docnum=3 %s -o %t 2>&1 | FileCheck --check-prefix=ERR2 %s
+
+# ERR2: a DWARFSectionSubtype is only allowed for a DWARF section
+
+--- !XCOFF
+FileHeader:
+  MagicNumber: 0x01DF
+  NumberOfSections: 2
+  CreationTime:    0
+  AuxiliaryHeaderSize: 0
+  Flags:           0x0
+Sections:
+  - Name:            .data
+    Address:         0x0
+    Size:            0x4
+    Flags:           [ STYP_DATA ]
+    DWARFSectionSubtype: SSUBTYP_DWABREV
+    SectionData:     '00000001'
+  - Name:            .dwabrev
+    Address:         0x0
+    Size:            0x4
+    Flags:           [ STYP_DWARF ]
+    SectionData:     01110125
+StringTable:     {}
+...