[llvm] [AsmPrinter][DebugNames] Implement DW_IDX_parent entries (PR #77457)

[David Blaikie via llvm-commits]

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@@ -395,36 +401,90 @@ void Dwarf5AccelTableWriter::Header::emit(Dwarf5AccelTableWriter &Ctx) {
   Asm->OutStreamer->emitBytes({AugmentationString, AugmentationStringSize});
 }
 
-static uint32_t constexpr LowerBitSize = dwarf::DW_IDX_type_hash;
+std::optional<uint64_t>
+DWARF5AccelTableData::getDefiningParentDieOffset(const DIE &Die) {
+  if (auto *Parent = Die.getParent();
+      Parent && !Parent->findAttribute(dwarf::Attribute::DW_AT_declaration))
+    return Parent->getOffset();
+  return {};
+}
+
+enum IdxParentEncoding : uint8_t {
+  NoIndexedParent = 0, /// Parent information present but parent isn't indexed.
+  Ref4 = 1,            /// Parent information present and parent is indexed.
+  NoParent = 2,        /// Parent information missing.
+};
+
+static uint32_t constexpr NumBitsIdxParent = 2;
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dwblaikie wrote:

I /think/ we usually put `constexpr` before the type name?

https://github.com/llvm/llvm-project/pull/77457