[DebugInfo] Improvements to representation of enumeration types (PR36168)

This patch is the LLVM part of fixing the issues, described in
https://bugs.llvm.org/show_bug.cgi?id=36168

* The representation of enumerator values in the debug info metadata now
  contains a boolean flag isUnsigned, which determines how the bits of
  the value are interpreted.
* The DW_TAG_enumeration type DIE now always (for DWARF version >= 3)
  includes a DW_AT_type attribute, which refers to the underlying
  integer type, as suggested in DWARFv4 (5.7 Enumeration Type Entries).
* The debug info metadata for enumeration type contains (in flags)
  indication whether this is a C++11 "fixed enum".
* For C++11 enumeration with a fixed underlying type, the DIE also
  includes the DW_AT_enum_class attribute (for DWARF version >= 4).
* Encoding of enumerator constants uses DW_FORM_sdata for signed values
  and DW_FORM_udata for unsigned values, as suggested by DWARFv4 (7.5.4
  Attribute Encodings).

The changes should be backwards compatible:

* the isUnsigned attribute is optional and defaults to false.
* if the underlying type for the enumeration is not available, the
  enumerator values are considered signed.
* the FixedEnum flag defaults to clear.
* the bitcode format for DIEnumerator stores the unsigned flag bit #1 of
  the first record element, so the format does not change and the zero
  previously stored there is consistent with the false default for
  IsUnsigned.

Differential Revision: https://reviews.llvm.org/D42734

llvm-svn: 324489

1 files changed, 7 insertions, 3 deletions

diff --git a/llvm/lib/IR/LLVMContextImpl.h b/llvm/lib/IR/LLVMContextImpl.h
index db7f368230d..c4cd7850f79 100644
--- a/llvm/lib/IR/LLVMContextImpl.h
+++ b/llvm/lib/IR/LLVMContextImpl.h
@@ -354,13 +354,17 @@ template <> struct MDNodeKeyImpl<DISubrange> {
 template <> struct MDNodeKeyImpl<DIEnumerator> {
   int64_t Value;
   MDString *Name;
+  bool IsUnsigned;
 
-  MDNodeKeyImpl(int64_t Value, MDString *Name) : Value(Value), Name(Name) {}
+  MDNodeKeyImpl(int64_t Value, bool IsUnsigned, MDString *Name)
+      : Value(Value), Name(Name), IsUnsigned(IsUnsigned) {}
   MDNodeKeyImpl(const DIEnumerator *N)
-      : Value(N->getValue()), Name(N->getRawName()) {}
+      : Value(N->getValue()), Name(N->getRawName()),
+        IsUnsigned(N->isUnsigned()) {}
 
   bool isKeyOf(const DIEnumerator *RHS) const {
-    return Value == RHS->getValue() && Name == RHS->getRawName();
+    return Value == RHS->getValue() && IsUnsigned == RHS->isUnsigned() &&
+           Name == RHS->getRawName();
   }
 
   unsigned getHashValue() const { return hash_combine(Value, Name); }