Unshift the GDB index/GNU pubnames constants modified in r191025

Based on code review feedback from Eric Christopher, unshifting these
constants as they can appear in the gdb_index itself, shifted a further
24 bits. This means that keeping them preshifted is a bit inflexible, so
let's not do that.

Given the motivation, wrap up some nicer enums, more type safety, and
some utility functions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191035 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 42 insertions, 31 deletions

diff --git a/include/llvm/Support/Dwarf.h b/include/llvm/Support/Dwarf.h
index f06c4801fd..9f969728cf 100644
--- a/include/llvm/Support/Dwarf.h
+++ b/include/llvm/Support/Dwarf.h
@@ -790,39 +790,50 @@ enum AcceleratorTable {
 const char *AtomTypeString(unsigned Atom);
 
 // Constants for the GNU pubnames/pubtypes extensions supporting gdb index.
-enum GDBIndex {
-  // The gnu_pub* index value looks like:
-  //
-  // 0-3  reserved
-  // 4-6  symbol kind
-  // 7    0 == global, 1 == static
-
-  // Attributes kinds for the index.
-  GDB_INDEX_SYMBOL_KIND_OFFSET = 4,
-  GDB_INDEX_SYMBOL_KIND_MASK = 7 << GDB_INDEX_SYMBOL_KIND_OFFSET,
-
-  // Special value to indicate no attributes are present.
-  GDB_INDEX_SYMBOL_KIND_NONE = 0,
-  GDB_INDEX_SYMBOL_KIND_TYPE = 1 << GDB_INDEX_SYMBOL_KIND_OFFSET,
-  GDB_INDEX_SYMBOL_KIND_VARIABLE = 2 << GDB_INDEX_SYMBOL_KIND_OFFSET,
-  GDB_INDEX_SYMBOL_KIND_FUNCTION = 3 << GDB_INDEX_SYMBOL_KIND_OFFSET,
-  GDB_INDEX_SYMBOL_KIND_OTHER = 4 << GDB_INDEX_SYMBOL_KIND_OFFSET,
-  // 3 unused values.
-  GDB_INDEX_SYMBOL_KIND_UNUSED5 = 5 << GDB_INDEX_SYMBOL_KIND_OFFSET,
-  GDB_INDEX_SYMBOL_KIND_UNUSED6 = 6 << GDB_INDEX_SYMBOL_KIND_OFFSET,
-  GDB_INDEX_SYMBOL_KIND_UNUSED7 = 7 << GDB_INDEX_SYMBOL_KIND_OFFSET,
-
-  // Index values are defined via the set of CUs that define the
-  // symbol. For the pubnames/pubtypes extensions we need the
-  // various shifts and masks.
-  GDB_INDEX_SYMBOL_STATIC_OFFSET = 7,
-  GDB_INDEX_SYMBOL_STATIC_MASK = 1 << GDB_INDEX_SYMBOL_STATIC_OFFSET,
-  GDB_INDEX_SYMBOL_STATIC = 1 << GDB_INDEX_SYMBOL_STATIC_OFFSET,
-  GDB_INDEX_SYMBOL_NON_STATIC = 0
+enum GDBIndexEntryKind {
+  GIEK_NONE,
+  GIEK_TYPE,
+  GIEK_VARIABLE,
+  GIEK_FUNCTION,
+  GIEK_OTHER,
+  GIEK_UNUSED5,
+  GIEK_UNUSED6,
+  GIEK_UNUSED7,
 };
 
-/// GDBIndexTypeString - Return the string for the specified index type.
-const char *GDBIndexTypeString(unsigned Kind);
+enum GDBIndexEntryLinkage {
+  GIEL_EXTERNAL,
+  GIEL_STATIC
+};
+
+/// The gnu_pub* kind looks like:
+///
+/// 0-3  reserved
+/// 4-6  symbol kind
+/// 7    0 == global, 1 == static
+///
+/// A gdb_index descriptor includes the above kind, shifted 24 bits up with the
+/// offset of the cu within the debug_info section stored in those 24 bits.
+struct PubIndexEntryDescriptor {
+  GDBIndexEntryKind Kind;
+  bool Static;
+  PubIndexEntryDescriptor(GDBIndexEntryKind Kind, bool Static)
+      : Kind(Kind), Static(Static) {}
+  /* implicit */ PubIndexEntryDescriptor(GDBIndexEntryKind Kind)
+      : Kind(Kind), Static(false) {}
+  explicit PubIndexEntryDescriptor(uint8_t Value)
+      : Kind(static_cast<GDBIndexEntryKind>((Value & KIND_MASK) >>
+                                            KIND_OFFSET)),
+        Static(Value & STATIC_MASK) {}
+  uint8_t toBits() {
+    return Kind << KIND_OFFSET | Static << STATIC_OFFSET;
+  }
+private:
+  const uint8_t KIND_OFFSET = 4;
+  const uint8_t KIND_MASK = 7 << KIND_OFFSET;
+  const uint8_t STATIC_OFFSET = 7;
+  const uint8_t STATIC_MASK = 1 << STATIC_OFFSET;
+};
 
 } // End of namespace dwarf