[PATCH] D27041: [ELF] - Disable emiting multiple output sections when merging is disabled.

[Rui Ueyama via Phabricator via llvm-commits]

ruiu added inline comments.


================
Comment at: ELF/InputSection.cpp:60-62
+  if (Config->Optimize == 0)
+    return Flags & ~(SHF_MERGE | SHF_STRINGS);
+  return Flags;
----------------
grimar wrote:
> ruiu wrote:
> > We shouldn't implement the same logic again here. You want to change this line https://github.com/llvm-mirror/lld/blob/d93aa5ab9ac56831d625a0233a0e17f482822d07/ELF/InputSection.cpp#L208to turn off SHF_MERGE and SHF_STRINGS flags unconditionally.
> That will not work unfortunately.
> Next code is involved here and not that line:
> 
> ```
>   if (shouldMerge(Sec))
>     return make<MergeInputSection<ELFT>>(this, &Sec, Name);
>   return make<InputSection<ELFT>>(this, &Sec, Name);
> ```
> calls:
> ```
> template <class ELFT>
> InputSection<ELFT>::InputSection(elf::ObjectFile<ELFT> *F,
>                                  const Elf_Shdr *Header, StringRef Name)
>     : InputSectionBase<ELFT>(F, Header, Name, Base::Regular) {}
> ```
> 
> So the suggested change will not take any affect on .data
But implementing the same logic here is not right.


================
Comment at: ELF/InputSection.cpp:91
   Alignment = V;
 }
 
----------------
How about this. You could add code here to drop the flag.

  // If it is not a mergeable section, overwrite the flag so that the flag
  // is consistent with the class. This inconsistency could occur when
  // string merging is disabled using -O0 flag.
  if (!isa<MergeInputSection<ELFT>>(this))
    Flags &= ~(SHF_MERGE | SHF_STRINGS);



https://reviews.llvm.org/D27041