ELF: Add support for the exclude section bit for gas compat.

llvm-svn: 190769

include/llvm/Support/ELF.h

@@ -1196,6 +1196,9 @@ enum {
   // This section holds Thread-Local Storage.
   SHF_TLS = 0x400U,
 
+  // This section is excluded from the final executable or shared library.
+  SHF_EXCLUDE = 0x80000000U,
+
   // Start of target-specific flags.
 
   /// XCORE_SHF_CP_SECTION - All sections with the "c" flag are grouped

lib/MC/MCParser/ELFAsmParser.cpp

@@ -279,14 +279,17 @@ static SectionKind computeSectionKind(unsigned Flags) {
   return SectionKind::getDataRel();
 }
 
-static int parseSectionFlags(StringRef flagsStr, bool *UseLastGroup) {
+static unsigned parseSectionFlags(StringRef flagsStr, bool *UseLastGroup) {
-  int flags = 0;
+  unsigned flags = 0;
 
   for (unsigned i = 0; i < flagsStr.size(); i++) {
     switch (flagsStr[i]) {
     case 'a':
       flags |= ELF::SHF_ALLOC;
       break;
+    case 'e':
+      flags |= ELF::SHF_EXCLUDE;
+      break;
     case 'x':
       flags |= ELF::SHF_EXECINSTR;
       break;
@@ -315,7 +318,7 @@ static int parseSectionFlags(StringRef flagsStr, bool *UseLastGroup) {
       *UseLastGroup = true;
       break;
     default:
-      return -1;
+      return -1U;
     }
   }
 
@@ -381,8 +384,8 @@ bool ELFAsmParser::ParseSectionArguments(bool IsPush) {
     StringRef FlagsStr = getTok().getStringContents();
     Lex();
 
-    int extraFlags = parseSectionFlags(FlagsStr, &UseLastGroup);
+    unsigned extraFlags = parseSectionFlags(FlagsStr, &UseLastGroup);
-    if (extraFlags < 0)
+    if (extraFlags == -1U)
       return TokError("unknown flag");
     Flags |= extraFlags;
 

lib/MC/MCSectionELF.cpp

@@ -75,6 +75,8 @@ void MCSectionELF::PrintSwitchToSection(const MCAsmInfo &MAI,
       OS << ",#execinstr";
     if (Flags & ELF::SHF_WRITE)
       OS << ",#write";
+    if (Flags & ELF::SHF_EXCLUDE)
+      OS << ",#exclude";
     if (Flags & ELF::SHF_TLS)
       OS << ",#tls";
     OS << '\n';
@@ -84,6 +86,8 @@ void MCSectionELF::PrintSwitchToSection(const MCAsmInfo &MAI,
   OS << ",\"";
   if (Flags & ELF::SHF_ALLOC)
     OS << 'a';
+  if (Flags & ELF::SHF_EXCLUDE)
+    OS << 'e';
   if (Flags & ELF::SHF_EXECINSTR)
     OS << 'x';
   if (Flags & ELF::SHF_GROUP)

lib/Object/ELFYAML.cpp

@@ -266,6 +266,7 @@ void ScalarBitSetTraits<ELFYAML::ELF_SHF>::bitset(IO &IO,
 #define BCase(X) IO.bitSetCase(Value, #X, ELF::X);
   BCase(SHF_WRITE)
   BCase(SHF_ALLOC)
+  BCase(SHF_EXCLUDE)
   BCase(SHF_EXECINSTR)
   BCase(SHF_MERGE)
   BCase(SHF_STRINGS)

test/MC/ELF/section.s

@@ -8,9 +8,9 @@
 .section	-.note.GNU,"",@progbits
 
 // CHECK: Name: .note.GNU-stack (56)
-// CHECK: Name: .note.GNU-stack2 (143)
+// CHECK: Name: .note.GNU-stack2 (153)
-// CHECK: Name: .note.GNU- (160)
+// CHECK: Name: .note.GNU- (170)
-// CHECK: Name: -.note.GNU (132)
+// CHECK: Name: -.note.GNU (142)
 
 // Test that the defaults are used
 
@@ -120,11 +120,28 @@ bar:
 // CHECK-NEXT:     EntrySize: 0
 // CHECK-NEXT:   }
 
+.section .excluded,"e",@progbits
+
+// CHECK:      Section {
+// CHECK:        Name: .excluded (92)
+// CHECK-NEXT:   Type: SHT_PROGBITS (0x1)
+// CHECK-NEXT:   Flags [ (0x80000000)
+// CHECK-NEXT:     SHF_EXCLUDE (0x80000000)
+// CHECK-NEXT:   ]
+// CHECK-NEXT:   Address: 0x0
+// CHECK-NEXT:   Offset: 0x50
+// CHECK-NEXT:   Size: 0
+// CHECK-NEXT:   Link: 0
+// CHECK-NEXT:   Info: 0
+// CHECK-NEXT:   AddressAlignment: 1
+// CHECK-NEXT:   EntrySize: 0
+// CHECK-NEXT: }
+
 // Test that we handle the strings like gas
 .section bar-"foo"
 .section "foo"
 
 // CHECK:        Section {
-// CHECK:          Name: bar-"foo" (171)
+// CHECK:          Name: bar-"foo" (181)
 // CHECK:        Section {
 // CHECK:          Name: foo (52)

tools/llvm-readobj/ELFDumper.cpp

@@ -377,6 +377,7 @@ static const char *getElfSectionType(unsigned Arch, unsigned Type) {
 static const EnumEntry<unsigned> ElfSectionFlags[] = {
   LLVM_READOBJ_ENUM_ENT(ELF, SHF_WRITE           ),
   LLVM_READOBJ_ENUM_ENT(ELF, SHF_ALLOC           ),
+  LLVM_READOBJ_ENUM_ENT(ELF, SHF_EXCLUDE         ),
   LLVM_READOBJ_ENUM_ENT(ELF, SHF_EXECINSTR       ),
   LLVM_READOBJ_ENUM_ENT(ELF, SHF_MERGE           ),
   LLVM_READOBJ_ENUM_ENT(ELF, SHF_STRINGS         ),