[Lldb-commits] [lldb] Enable LLDB to load large dSYM files. (PR #164471)

[Ellis Hoag via lldb-commits]

================
@@ -1697,6 +1701,14 @@ void ObjectFileMachO::ProcessSegmentCommand(
     // isn't stored in the abstracted Sections.
     m_mach_sections.push_back(sect64);
 
+    // Make sure we can load dSYM files whose __DWARF sections exceed the 4GB
+    // barrier. llvm::MachO::section_64 have only 32 bit file offsets for the
+    // section contents.
+    const uint64_t section_file_offset = sect64.offset + section_offset_adjust;
+    // If this section overflows a 4GB barrier, then we need to adjust any
+    // subsequent the section offsets.
+    if (is_dsym && ((uint64_t)sect64.offset + sect64.size) >= UINT32_MAX)
+      section_offset_adjust += 0x100000000ull;
----------------
ellishg wrote:

I know it's an edge case, but I believe this will be incorrect if `sect64.size > 2^32`. I would suggest masking out the lower 32 bits and adding that to the adjust value, but there might be a cleaner way.

```suggestion
    if (is_dsym && ((uint64_t)sect64.offset + sect64.size) >= UINT32_MAX)
      section_offset_adjust += ~((1 << 32) - 1) & ((uint64_t)sect64.offset + sect64.size);
```

https://github.com/llvm/llvm-project/pull/164471