r336664 | emaste | 2018-07-24 13:35:22 +0200 (Tue, 24 Jul 2018) | 11 lines

lld: fix addends with partial linking

[ELF] Update addends in non-allocatable sections for REL targets when
creating a relocatable output.

LLVM PR: 37735
LLVM Differential Revision: https://reviews.llvm.org/D48929

PR:		225128
Obtained from:	LLVM r336799 by Igor Kudrin

Index: tools/lld/ELF/InputSection.cpp
===================================================================
--- tools/lld/ELF/InputSection.cpp	(revision 336663)
+++ tools/lld/ELF/InputSection.cpp	(revision 336664)
@@ -686,6 +686,23 @@ void InputSection::relocateNonAlloc(uint8_t *Buf,
   }
 }
 
+// This is used when '-r' is given.
+// For REL targets, InputSection::copyRelocations() may store artificial
+// relocations aimed to update addends. They are handled in relocateAlloc()
+// for allocatable sections, and this function does the same for
+// non-allocatable sections, such as sections with debug information.
+static void relocateNonAllocForRelocatable(InputSection *Sec, uint8_t *Buf) {
+  const unsigned Bits = Config->Is64 ? 64 : 32;
+
+  for (const Relocation &Rel : Sec->Relocations) {
+    // InputSection::copyRelocations() adds only R_ABS relocations.
+    assert(Rel.Expr == R_ABS);
+    uint8_t *BufLoc = Buf + Rel.Offset + Sec->OutSecOff;
+    uint64_t TargetVA = SignExtend64(Rel.Sym->getVA(Rel.Addend), Bits);
+    Target->relocateOne(BufLoc, Rel.Type, TargetVA);
+  }
+}
+
 template <class ELFT>
 void InputSectionBase::relocate(uint8_t *Buf, uint8_t *BufEnd) {
   if (Flags & SHF_ALLOC) {
@@ -694,7 +711,9 @@ void InputSectionBase::relocate(uint8_t *Buf, uint
   }
 
   auto *Sec = cast<InputSection>(this);
-  if (Sec->AreRelocsRela)
+  if (Config->Relocatable)
+    relocateNonAllocForRelocatable(Sec, Buf);
+  else if (Sec->AreRelocsRela)
     Sec->relocateNonAlloc<ELFT>(Buf, Sec->template relas<ELFT>());
   else
     Sec->relocateNonAlloc<ELFT>(Buf, Sec->template rels<ELFT>());