[llvm] [LLVM][DebugInfo] Refactor some code for easier sharing. (PR #82153)

[David Blaikie via llvm-commits]

================
@@ -552,32 +552,52 @@ DWARFDebugNames::NameIndex::extractAbbrev(uint64_t *Offset) {
   return Abbrev(Code, dwarf::Tag(Tag), AbbrevOffset, std::move(*AttrEncOr));
 }
 
+uint64_t
+llvm::FindDebugNamesOffsets(DWARFDebugNames::DWARFDebugNamesOffsets &Offsets,
+                            uint64_t HdrSize, dwarf::DwarfFormat Format,
+                            const DWARFDebugNames::Header &Hdr) {
+  uint32_t DwarfSize = (Format == llvm::dwarf::DwarfFormat::DWARF32) ? 4 : 8;
+  uint64_t Offset = HdrSize;
+  Offsets.CUsBase = Offset;
+  Offset += Hdr.CompUnitCount * DwarfSize;
+  Offset += Hdr.LocalTypeUnitCount * DwarfSize;
+  Offset += Hdr.ForeignTypeUnitCount * 8;
+
+  Offsets.BucketsBase = Offset;
+  Offset += Hdr.BucketCount * 4;
+
+  Offsets.HashesBase = Offset;
+  if (Hdr.BucketCount > 0)
+    Offset += Hdr.NameCount * 4;
+
+  Offsets.StringOffsetsBase = Offset;
+  Offset += Hdr.NameCount * DwarfSize;
+
+  Offsets.EntryOffsetsBase = Offset;
+  Offset += Hdr.NameCount * DwarfSize;
+
+  Offset += Hdr.AbbrevTableSize;
+  Offsets.EntriesBase = Offset;
+
+  return Offset;
+}
+
 Error DWARFDebugNames::NameIndex::extract() {
   const DWARFDataExtractor &AS = Section.AccelSection;
   uint64_t Offset = Base;
   if (Error E = Hdr.extract(AS, &Offset))
     return E;
 
   const unsigned SectionOffsetSize = dwarf::getDwarfOffsetByteSize(Hdr.Format);
-  CUsBase = Offset;
-  Offset += Hdr.CompUnitCount * SectionOffsetSize;
-  Offset += Hdr.LocalTypeUnitCount * SectionOffsetSize;
-  Offset += Hdr.ForeignTypeUnitCount * 8;
-  BucketsBase = Offset;
-  Offset += Hdr.BucketCount * 4;
-  HashesBase = Offset;
-  if (Hdr.BucketCount > 0)
-    Offset += Hdr.NameCount * 4;
-  StringOffsetsBase = Offset;
-  Offset += Hdr.NameCount * SectionOffsetSize;
-  EntryOffsetsBase = Offset;
-  Offset += Hdr.NameCount * SectionOffsetSize;
+  Offset = FindDebugNamesOffsets(Offsets, Offset, Hdr.Format, Hdr);
----------------
dwblaikie wrote:

This is strange that we assign to `Offset`, but then overwrite it on the next line?

So what's the return value for? Perhaps if it's needed by the future callers but not right now - maybe it should be in the `Offsets` structure, and that `Offsets` structure should be returned by this function, rather than as an input parameter?

https://github.com/llvm/llvm-project/pull/82153