Make the big switch: Change MCSectionMachO to represent a section *semantically*

instead of syntactically as a string.  This means that it keeps track of the 
segment, section, flags, etc directly and asmprints them in the right format.
This also includes parsing and validation support for llvm-mc and 
"attribute(section)", so we should now start getting errors about invalid 
section attributes from the compiler instead of the assembler on darwin.

Still todo: 
1) Uniquing of darwin mcsections
2) Move all the Darwin stuff out to MCSectionMachO.[cpp|h]
3) there are a few FIXMEs, for example what is the syntax to get the
   S_GB_ZEROFILL segment type?

llvm-svn: 78547

Author: lattner

llvm/include/llvm/MC/MCSection.h

@@ -67,25 +67,154 @@ namespace llvm {
                                       raw_ostream &OS) const;
   };
 
+  
+  /// MCSectionMachO - This represents a section on a Mach-O system (used by
+  /// Mac OS X).  On a Mac system, these are also described in
+  /// /usr/include/mach-o/loader.h.
   class MCSectionMachO : public MCSection {
-    std::string Name;
+    char SegmentName[16];  // Not necessarily null terminated!
+    char SectionName[16];  // Not necessarily null terminated!
 
-    /// IsDirective - This is true if the section name is a directive, not
-    /// something that should be printed with ".section".
-    ///
-    /// FIXME: This is a hack.  Switch to a semantic view of the section instead
-    /// of a syntactic one.
-    bool IsDirective;
+    /// TypeAndAttributes - This is the SECTION_TYPE and SECTION_ATTRIBUTES
+    /// field of a section, drawn from the enums below.
+    unsigned TypeAndAttributes;
+    
+    /// Reserved2 - The 'reserved2' field of a section, used to represent the
+    /// size of stubs, for example.
+    unsigned Reserved2;
 
-    MCSectionMachO(const StringRef &Name, bool IsDirective, SectionKind K,
-                   MCContext &Ctx);
+    MCSectionMachO(const StringRef &Segment, const StringRef &Section,
+                   unsigned TAA, unsigned reserved2, SectionKind K)
+      : MCSection(K), TypeAndAttributes(TAA), Reserved2(reserved2) {
+      assert(Segment.size() <= 16 && Section.size() <= 16 &&
+             "Segment or section string too long");
+      for (unsigned i = 0; i != 16; ++i) {
+        if (i < Segment.size())
+          SegmentName[i] = Segment[i];
+        else
+          SegmentName[i] = 0;
+        
+        if (i < Section.size())
+          SectionName[i] = Section[i];
+        else
+          SectionName[i] = 0;
+      }        
+    }
   public:
 
-    static MCSectionMachO *Create(const StringRef &Name, bool IsDirective, 
+    static MCSectionMachO *Create(const StringRef &Segment,
+                                  const StringRef &Section,
+                                  unsigned TypeAndAttributes,
+                                  unsigned Reserved2,
                                   SectionKind K, MCContext &Ctx);
+    
+    /// These are the section type and attributes fields.  A MachO section can
+    /// have only one Type, but can have any of the attributes specified.
+    enum {
+      // TypeAndAttributes bitmasks.
+      SECTION_TYPE       = 0x000000FFU,
+      SECTION_ATTRIBUTES = 0xFFFFFF00U,
+      
+      // Valid section types.
+      
+      /// S_REGULAR - Regular section.
+      S_REGULAR                    = 0x00U,
+      /// S_ZEROFILL - Zero fill on demand section.
+      S_ZEROFILL                   = 0x01U,
+      /// S_CSTRING_LITERALS - Section with literal C strings.
+      S_CSTRING_LITERALS           = 0x02U,
+      /// S_4BYTE_LITERALS - Section with 4 byte literals.
+      S_4BYTE_LITERALS             = 0x03U,
+      /// S_8BYTE_LITERALS - Section with 8 byte literals.
+      S_8BYTE_LITERALS             = 0x04U,
+      /// S_LITERAL_POINTERS - Section with pointers to literals.
+      S_LITERAL_POINTERS           = 0x05U,
+      /// S_NON_LAZY_SYMBOL_POINTERS - Section with non-lazy symbol pointers.
+      S_NON_LAZY_SYMBOL_POINTERS   = 0x06U,
+      /// S_LAZY_SYMBOL_POINTERS - Section with lazy symbol pointers.
+      S_LAZY_SYMBOL_POINTERS       = 0x07U,
+      /// S_SYMBOL_STUBS - Section with symbol stubs, byte size of stub in
+      /// the Reserved2 field.
+      S_SYMBOL_STUBS               = 0x08U,
+      /// S_SYMBOL_STUBS - Section with only function pointers for
+      /// initialization.
+      S_MOD_INIT_FUNC_POINTERS     = 0x09U,
+      /// S_MOD_INIT_FUNC_POINTERS - Section with only function pointers for
+      /// termination.
+      S_MOD_TERM_FUNC_POINTERS     = 0x0AU,
+      /// S_COALESCED - Section contains symbols that are to be coalesced.
+      S_COALESCED                  = 0x0BU,
+      /// S_GB_ZEROFILL - Zero fill on demand section (that can be larger than 4
+      /// gigabytes).
+      S_GB_ZEROFILL                = 0x0CU,
+      /// S_INTERPOSING - Section with only pairs of function pointers for
+      /// interposing.
+      S_INTERPOSING                = 0x0DU,
+      /// S_16BYTE_LITERALS - Section with only 16 byte literals.
+      S_16BYTE_LITERALS            = 0x0EU,
+      /// S_DTRACE_DOF - Section contains DTrace Object Format.
+      S_DTRACE_DOF                 = 0x0FU,
+      /// S_LAZY_DYLIB_SYMBOL_POINTERS - Section with lazy symbol pointers to
+      /// lazy loaded dylibs.
+      S_LAZY_DYLIB_SYMBOL_POINTERS = 0x10U,
 
-    const std::string &getName() const { return Name; }
-    bool isDirective() const { return IsDirective; }
+      LAST_KNOWN_SECTION_TYPE = S_LAZY_DYLIB_SYMBOL_POINTERS,
+      
+
+      // Valid section attributes.
+      
+      /// S_ATTR_PURE_INSTRUCTIONS - Section contains only true machine
+      /// instructions.
+      S_ATTR_PURE_INSTRUCTIONS   = 1U << 31,
+      /// S_ATTR_NO_TOC - Section contains coalesced symbols that are not to be
+      /// in a ranlib table of contents.
+      S_ATTR_NO_TOC              = 1U << 30,
+      /// S_ATTR_STRIP_STATIC_SYMS - Ok to strip static symbols in this section
+      /// in files with the MY_DYLDLINK flag.
+      S_ATTR_STRIP_STATIC_SYMS   = 1U << 29,
+      /// S_ATTR_NO_DEAD_STRIP - No dead stripping.
+      S_ATTR_NO_DEAD_STRIP       = 1U << 28,
+      /// S_ATTR_LIVE_SUPPORT - Blocks are live if they reference live blocks.
+      S_ATTR_LIVE_SUPPORT        = 1U << 27,
+      /// S_ATTR_SELF_MODIFYING_CODE - Used with i386 code stubs written on by
+      /// dyld.
+      S_ATTR_SELF_MODIFYING_CODE = 1U << 26,
+      /// S_ATTR_DEBUG - A debug section.
+      S_ATTR_DEBUG               = 1U << 25,
+      /// S_ATTR_SOME_INSTRUCTIONS - Section contains some machine instructions.
+      S_ATTR_SOME_INSTRUCTIONS   = 1U << 10,
+      /// S_ATTR_EXT_RELOC - Section has external relocation entries.
+      S_ATTR_EXT_RELOC           = 1U << 9,
+      /// S_ATTR_LOC_RELOC - Section has local relocation entries.
+      S_ATTR_LOC_RELOC           = 1U << 8
+    };
+
+    StringRef getSegmentName() const {
+      // SegmentName is not necessarily null terminated!
+      if (SegmentName[15])
+        return StringRef(SegmentName, 16);
+      return StringRef(SegmentName);
+    }
+    StringRef getSectionName() const {
+      // SectionName is not necessarily null terminated!
+      if (SectionName[15])
+        return StringRef(SectionName, 16);
+      return StringRef(SectionName);
+    }
+    
+    unsigned getTypeAndAttributes() const { return TypeAndAttributes; }
+    
+    
+    /// ParseSectionSpecifier - Parse the section specifier indicated by "Spec".
+    /// This is a string that can appear after a .section directive in a mach-o
+    /// flavored .s file.  If successful, this fills in the specified Out
+    /// parameters and returns an empty string.  When an invalid section
+    /// specifier is present, this returns a string indicating the problem.
+    static std::string ParseSectionSpecifier(StringRef Spec,       // In.
+                                             StringRef &Segment,   // Out.
+                                             StringRef &Section,   // Out.
+                                             unsigned  &TAA,       // Out.
+                                             unsigned  &StubSize); // Out.
 
     virtual void PrintSwitchToSection(const TargetAsmInfo &TAI,
                                       raw_ostream &OS) const;

llvm/include/llvm/Target/TargetLoweringObjectFile.h

@@ -257,9 +257,30 @@ class TargetLoweringObjectFileMachO : public TargetLoweringObjectFile {
                                           Mangler *) const;
 
   /// getMachOSection - Return the MCSection for the specified mach-o section.
-  /// FIXME: Switch this to a semantic view eventually.
-  const MCSection *getMachOSection(const char *Name, bool isDirective,
-                                   SectionKind K) const;
+  /// This requires the operands to be valid.
+  const MCSection *getMachOSection(StringRef Segment, StringRef Section,
+                                   unsigned TypeAndAttributes,
+                                   SectionKind K) const {
+    return getMachOSection(Segment, Section, TypeAndAttributes, 0, K);
+  }
+  const MCSection *getMachOSection(StringRef Segment, StringRef Section,
+                                   unsigned TypeAndAttributes,
+                                   unsigned Reserved2, SectionKind K) const;
+
+  /// getTextCoalSection - Return the "__TEXT,__textcoal_nt" section we put weak
+  /// symbols into.
+  const MCSection *getTextCoalSection() const {
+    return TextCoalSection;
+  }
+  
+  /// getLazySymbolPointerSection - Return the section corresponding to
+  /// the .lazy_symbol_pointer directive.
+  const MCSection *getLazySymbolPointerSection() const;
+  
+  /// getNonLazySymbolPointerSection - Return the section corresponding to
+  /// the .non_lazy_symbol_pointer directive.
+  const MCSection *getNonLazySymbolPointerSection() const;
+  
 };
 
 

llvm/lib/MC/MCAsmStreamer.cpp

@@ -222,7 +222,9 @@ void MCAsmStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
   OS << ".zerofill ";
 
   // This is a mach-o specific directive.
-  OS << '"' << ((MCSectionMachO*)Section)->getName() << '"';
+  const MCSectionMachO *MOSection = ((const MCSectionMachO*)Section);
+  OS << '"' << MOSection->getSegmentName() << ","
+     << MOSection->getSectionName() << '"';
 
 
   if (Symbol != NULL) {