[lld] r249397 - External symbols need a full dynamic reloc, not R_X86_64_RELATIVE.

[Rafael Espindola via llvm-commits]

Author: rafael
Date: Tue Oct  6 07:39:58 2015
New Revision: 249397

URL: http://llvm.org/viewvc/llvm-project?rev=249397&view=rev
Log:
External symbols need a full dynamic reloc, not R_X86_64_RELATIVE.

We were already doing the right thing if the symbol was seen in a shared
library, but not if it was completely missing.

Modified:
    lld/trunk/ELF/OutputSections.cpp
    lld/trunk/test/elf2/relative-dynamic-reloc.s

Modified: lld/trunk/ELF/OutputSections.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/OutputSections.cpp?rev=249397&r1=249396&r2=249397&view=diff
==============================================================================
--- lld/trunk/ELF/OutputSections.cpp (original)
+++ lld/trunk/ELF/OutputSections.cpp Tue Oct  6 07:39:58 2015
@@ -92,6 +92,12 @@ RelocationSection<ELFT>::RelocationSecti
   this->Header.sh_addralign = ELFT::Is64Bits ? 8 : 4;
 }
 
+static bool isLocalDefinition(const SymbolBody *Body) {
+  if (!Body)
+    return true;
+  return !Body->isShared() && !Body->isUndefined();
+}
+
 template <class ELFT> void RelocationSection<ELFT>::writeTo(uint8_t *Buf) {
   const unsigned EntrySize = IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
   bool IsMips64EL = Relocs[0].C.getFile()->getObj().isMips64EL();
@@ -118,7 +124,7 @@ template <class ELFT> void RelocationSec
       if (IsRela)
         Addent = static_cast<const Elf_Rela &>(RI).r_addend;
 
-      if (Body && Body->isShared()) {
+      if (!isLocalDefinition(Body)) {
         P->setSymbolAndType(Body->getDynamicSymbolTableIndex(), Type,
                             IsMips64EL);
       } else {

Modified: lld/trunk/test/elf2/relative-dynamic-reloc.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/elf2/relative-dynamic-reloc.s?rev=249397&r1=249396&r2=249397&view=diff
==============================================================================
--- lld/trunk/test/elf2/relative-dynamic-reloc.s (original)
+++ lld/trunk/test/elf2/relative-dynamic-reloc.s Tue Oct  6 07:39:58 2015
@@ -12,6 +12,7 @@
 // CHECK-NEXT:     0x2010 R_X86_64_RELATIVE - 0x2009
 // CHECK-NEXT:     0x{{.*}} R_X86_64_RELATIVE - 0x[[ZED_ADDR:.*]]
 // CHECK-NEXT:     0x{{.*}} R_X86_64_RELATIVE - 0x[[FOO_ADDR]]
+// CHECK-NEXT:     0x1008 R_X86_64_64 external 0x0
 // CHECK-NEXT:   }
 // CHECK-NEXT: ]
 
@@ -34,6 +35,15 @@
 // CHECK-NEXT:     Other: 0
 // CHECK-NEXT:     Section: Undefined
 // CHECK-NEXT:   }
+// CHECK-NEXT:   Symbol {
+// CHECK-NEXT:     Name: external@
+// CHECK-NEXT:     Value: 0x0
+// CHECK-NEXT:     Size: 0
+// CHECK-NEXT:     Binding: Global
+// CHECK-NEXT:     Type: None
+// CHECK-NEXT:     Other: 0
+// CHECK-NEXT:     Section: Undefined
+// CHECK-NEXT:   }
 // CHECK-NEXT: ]
 
 foo:
@@ -51,3 +61,5 @@ bar:
 
         .section abc,"a"
         .quad foo
+
+        .quad external