[PATCH] D40026: [ELF] - Allow applying SHF_MERGE optimization for relocatable output.

[George Rimar via Phabricator via llvm-commits]

grimar added inline comments.


================
Comment at: ELF/Writer.cpp:494
+    // which is used for -r.
+    if (isa<SyntheticSection>(IS) && !(IS->Flags & SHF_MERGE))
+      continue;
----------------
ruiu wrote:
> grimar wrote:
> > ruiu wrote:
> > > I wonder if you really need to handle this as a special case.
> > Do you mean we can create symbols for all synthetic sections instead ? I think that is at least confusing to see in output and excessive.
> Well, I mean I actually do not understand what this code is for in the first place.
It is for this place:
https://github.com/llvm-mirror/lld/blob/master/ELF/SyntheticSections.cpp#L1529

When we rewrite relocations we updating info field and want to set proper section index.
Before this patch we had regular SHF_MERGE sections in output, so symbols were created for them.
But now them are synthetic and there is no symbol, so we emit wrong zero index and relocation is broken.

BTW, I think that affects regular output + --emit-relocs as well. I am going to check soon and will split that change to different patch if so.


https://reviews.llvm.org/D40026