Fix crash with -emit-relocs -shared.

The code to handle the input SHT_REL/SHT_RELA sections was getting
confused with the linker generated relocation sections.

llvm-svn: 295322
diff --git a/lld/ELF/OutputSections.cpp b/lld/ELF/OutputSections.cpp
index 25ea64a..d1f760d 100644
--- a/lld/ELF/OutputSections.cpp
+++ b/lld/ELF/OutputSections.cpp
@@ -119,10 +119,14 @@
   if (!Config->copyRelocs() || (Type != SHT_RELA && Type != SHT_REL))
     return;
 
+  InputSection<ELFT> *First = Sections[0];
+  if (isa<SyntheticSection<ELFT>>(First))
+    return;
+
   this->Link = In<ELFT>::SymTab->OutSec->SectionIndex;
   // sh_info for SHT_REL[A] sections should contain the section header index of
   // the section to which the relocation applies.
-  InputSectionBase<ELFT> *S = Sections[0]->getRelocatedSection();
+  InputSectionBase<ELFT> *S = First->getRelocatedSection();
   this->Info = S->OutSec->SectionIndex;
 }
 
diff --git a/lld/test/ELF/emit-relocs-shared.s b/lld/test/ELF/emit-relocs-shared.s
new file mode 100644
index 0000000..7a0d791
--- /dev/null
+++ b/lld/test/ELF/emit-relocs-shared.s
@@ -0,0 +1,16 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+# RUN: ld.lld --emit-relocs %t.o -o %t.so -shared
+# RUN: llvm-readobj -r %t.so | FileCheck %s
+
+.data
+.quad foo
+
+# CHECK:      Relocations [
+# CHECK-NEXT:   Section (4) .rela.dyn {
+# CHECK-NEXT:     0x1000 R_X86_64_64 foo 0x0
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Section (8) .rela.data {
+# CHECK-NEXT:     0x1000 R_X86_64_64 foo 0x0
+# CHECK-NEXT:   }
+# CHECK-NEXT: ]