[PATCH] D13566: [ELF2] PPC64 needs to delay local-call relocations until after the function-descriptor values are known

[Rui Ueyama via llvm-commits]

ruiu added inline comments.

================
Comment at: ELF/Target.cpp:401-407
@@ -400,1 +400,9 @@
+
+    if (!ForPltEntry) {
+      // If this is a local call, and we currently have the address of a
+      // function-descriptor, get the underlying code address instead.
+      auto ARI = Addr64Relocs.find(R);
+      if (ARI != Addr64Relocs.end())
+        R = ARI->second;
+    }
 
----------------
hfinkel wrote:
> ruiu wrote:
> > You may be able to eliminate the hash table by reading back previous relocatino results for R_PPC64_ADDR64 from Buf.
> > 
> >   if (!ForPltEntry)
> >     R = read64be(Buf + R - BaseAddr);
> Two problems:
> 
>  1. The relocated addresses are in a different section (and, thus, I assume, have a different base buffer pointer)
> 
>  2. If the relocation is not pointing to a function descriptor (which it might not), then we need to keep the original symbol address.
> 
> An alternative would be to be able to explicitly get the .opd section, do a bounds check (just as I do for the .plt section), and then read from its buffer. Is there a good way to do that?
> 
Ah, you are right. But how about keeping a pointer to .opd section? If you have a pointer to .opd section, can you get the value you want from the section contents?


http://reviews.llvm.org/D13566