[lld] r248054 - [elf2] Relocate against common symbols.

[Michael J. Spencer via llvm-commits]

Author: mspencer
Date: Fri Sep 18 17:13:25 2015
New Revision: 248054

URL: http://llvm.org/viewvc/llvm-project?rev=248054&view=rev
Log:
[elf2] Relocate against common symbols.

Added:
    lld/trunk/test/elf2/relocation-common.s
Modified:
    lld/trunk/ELF/Symbols.h
    lld/trunk/ELF/Writer.cpp

Modified: lld/trunk/ELF/Symbols.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Symbols.h?rev=248054&r1=248053&r2=248054&view=diff
==============================================================================
--- lld/trunk/ELF/Symbols.h (original)
+++ lld/trunk/ELF/Symbols.h Fri Sep 18 17:13:25 2015
@@ -24,6 +24,7 @@ class Chunk;
 class InputFile;
 class SymbolBody;
 template <class ELFT> class ObjectFile;
+template <class ELFT> class OutputSection;
 
 // A real symbol object, SymbolBody, is usually accessed indirectly
 // through a Symbol. There's always one Symbol for each symbol name.
@@ -180,6 +181,8 @@ public:
 
   // The maximum alignment we have seen for this symbol.
   uintX_t MaxAlignment;
+
+  OutputSection<ELFT> *OutputSec = nullptr;
 };
 
 // Regular defined symbols read from object file symbol tables.

Modified: lld/trunk/ELF/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=248054&r1=248053&r2=248054&view=diff
==============================================================================
--- lld/trunk/ELF/Writer.cpp (original)
+++ lld/trunk/ELF/Writer.cpp Fri Sep 18 17:13:25 2015
@@ -738,8 +738,11 @@ void OutputSection<ELFT>::relocate(
     case SymbolBody::DefinedAbsoluteKind:
       SymVA = cast<DefinedAbsolute<ELFT>>(Body)->Sym.st_value;
       break;
-    case SymbolBody::DefinedCommonKind:
-      continue;
+    case SymbolBody::DefinedCommonKind: {
+      auto *DC = cast<DefinedCommon<ELFT>>(Body);
+      SymVA = DC->OutputSec->getVA() + DC->OffsetInBSS;
+      break;
+    }
     case SymbolBody::SharedKind:
       if (!relocNeedsGOT(Type))
         continue;
@@ -1063,6 +1066,7 @@ template <class ELFT> void Writer<ELFT>:
     uintX_t Align = C->MaxAlignment;
     Off = RoundUpToAlignment(Off, Align);
     C->OffsetInBSS = Off;
+    C->OutputSec = BSSSec;
     Off += Sym.st_size;
   }
 

Added: lld/trunk/test/elf2/relocation-common.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/elf2/relocation-common.s?rev=248054&view=auto
==============================================================================
--- lld/trunk/test/elf2/relocation-common.s (added)
+++ lld/trunk/test/elf2/relocation-common.s Fri Sep 18 17:13:25 2015
@@ -0,0 +1,14 @@
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t
+// RUN: lld -flavor gnu2 %t -o %tout
+// RUN: llvm-objdump -t -d %tout | FileCheck %s
+// REQUIRES: x86
+
+.global _start
+_start:
+  movl $1, sym1(%rip)
+
+.global sym1
+.comm sym1,4,4
+
+// CHECK: 11000: {{.*}} movl    $1, 4086(%rip)
+// CHECK: 0000000000012000 g       .bss            00000004 sym1