[PATCH] D59958: [llvm-objcopy] Change SHT_NOBITS to SHT_PROBITS for some --set-section-flags

[Fangrui Song via Phabricator via llvm-commits]

MaskRay added inline comments.


================
Comment at: llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp:107
+       SectionFlag::SecRom | SectionFlag::SecDebug))
+    Sec.Type = SHT_PROGBITS;
+}
----------------
rupprecht wrote:
> jhenderson wrote:
> > Won't this change the type of other non-NOBITS sections (e.g. SHT_RELA or SHT_DYNSYM)? Is that intended (I suspect not...)?
> I did some experimentation with gnu objcopy.
> * For some sections (rela, symtab, init_array), it never touched the section type, *or* SHF flags (so we're actually already different there)
> * For some sections like .gnu.hash, it *always* changed it to progbits (even for flags like alloc that don't change nobits to progbits).
> Fixed this to only change the type if the old type is NOBITS.
`SHT_NULL` may also change but it may not have much sense.

Other than that, `SHT_NOBITS` -> `SHT_PROGBITS` is the only possible change. I believe GNU objcopy's rule is similar to the following:

```
          if (Sec.Type == SHT_NOTES && NewFlags & SectionFlags::SecAlloc &&
              NewFlags & !(SectionFlags::SecLoad))
            Sec.Type = SHT_PROGBITS;
```


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D59958/new/

https://reviews.llvm.org/D59958