[PATCH] D59958: [llvm-objcopy] Change SHT_NOBITS to SHT_PROBITS for some --set-section-flags
Fangrui Song via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Sat Mar 30 08:56:48 PDT 2019
MaskRay added inline comments.
================
Comment at: llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp:107
+ SectionFlag::SecRom | SectionFlag::SecDebug))
+ Sec.Type = SHT_PROGBITS;
+}
----------------
MaskRay wrote:
> 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;
> ```
Sorry, excessive `!`. It should be:
```
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
More information about the llvm-commits
mailing list