[PPC64] Sort .toc sections accessed with small code model relocs.

A follow up to the intial patch that unblocked linking against libgcc.
For lld we don't need to bother tracking which objects have got based small
code model relocations. This is due to the fact that the compilers on
powerpc64 use the .toc section to generate indirections to symbols (rather then
using got relocations) which keeps the got small. This makes overflowing a
small code model got relocation very unlikely.

Differential Revision: https://reviews.llvm.org/D57245

llvm-svn: 353849

1 files changed, 10 insertions, 2 deletions

diff --git a/lld/ELF/Relocations.cpp b/lld/ELF/Relocations.cpp
index 70aa7ba5594..7de2c05ffc6 100644
--- a/lld/ELF/Relocations.cpp
+++ b/lld/ELF/Relocations.cpp
@@ -1000,8 +1000,16 @@ static void scanReloc(InputSectionBase &Sec, OffsetGetter &GetOffset, RelTy *&I,
   if (isRelExprOneOf<R_HINT, R_NONE>(Expr))
     return;
 
-  if (Config->EMachine == EM_PPC64 && isPPC64SmallCodeModelReloc(Type))
-    Sec.File->PPC64SmallCodeModelRelocs = true;
+  // We can separate the small code model relocations into 2 categories:
+  // 1) Those that access the compiler generated .toc sections.
+  // 2) Those that access the linker allocated got entries.
+  // lld allocates got entries to symbols on demand. Since we don't try to sort
+  // the got entries in any way, we don't have to track which objects have
+  // got-based small code model relocs. The .toc sections get placed after the
+  // end of the linker allocated .got section and we do sort those so sections
+  // addressed with small code model relocations come first.
+  if (Config->EMachine == EM_PPC64 && isPPC64SmallCodeModelTocReloc(Type))
+    Sec.File->PPC64SmallCodeModelTocRelocs = true;
 
   // Strengthen or relax relocations.
   //