[PATCH] D157036: Emit a .debug_str_offsets section with dsymutil to support DW_FORM_strx in dsymutil.

[Alexey Lapshin via Phabricator via llvm-commits]

avl added inline comments.


================
Comment at: llvm/lib/DWARFLinker/DWARFLinker.cpp:1063
       Info.MangledName = StringEntry;
-
+    if (AttrSpec.Form == dwarf::DW_FORM_strx ||
+        (AttrSpec.Form >= dwarf::DW_FORM_strx1 &&
----------------
I would suggest to use DwarfVersion as a sign of which resulting form would be used:

```
if (DwarfVersion >= 5) {
      // Switch everything to DW_FORM_strx strings.
      auto StringOffsetIndex =
          StringOffsetPool.getValueIndex(StringEntry.getOffset());
      return Die
          .addValue(DIEAlloc, AttrSpec.Attr,
                    dwarf::DW_FORM_strx, DIEInteger(StringOffsetIndex))
          ->sizeOf(U.getFormParams());
}

    // Switch everything to DW_FORM_strp strings.
    return Die
          .addValue(DIEAlloc, AttrSpec.Attr,
                    dwarf::DW_FORM_strp, DIEInteger(StringEntry.getOffset()))
          ->sizeOf(U.getFormParams());

```

This allows to save more space if original CU is of 5 version but uses DW_FORM_strp forms. Also it would allow to simplify patch by removing StrxFoundInCU and AttrStrOffsetBaseSeen flags. 

Though we would need to pay attention to the case when original CU of 5 dwarf version does not have  DW_AT_str_offsets_base because it uses DW_FORM_strp forms. We would need to add DW_AT_str_offsets_base in that case.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D157036/new/

https://reviews.llvm.org/D157036