[PATCH] D47975: [ELF] Fix copy relocation when two symbols share the same Symbol instance.

[Fangrui Song via Phabricator via llvm-commits]

MaskRay updated this revision to Diff 150810.
MaskRay marked an inline comment as done.
MaskRay added a comment.

Add test


Repository:
  rLLD LLVM Linker

https://reviews.llvm.org/D47975

Files:
  ELF/Relocations.cpp
  test/ELF/copy-rel-version.s


Index: test/ELF/copy-rel-version.s
===================================================================
--- /dev/null
+++ test/ELF/copy-rel-version.s
@@ -0,0 +1,15 @@
+// REQUIRES: x86
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/copy-rel-version.s -o %t1.o
+// RUN: echo "v1 {}; v2 {};" > %t.ver
+// RUN: ld.lld %t1.o -shared -soname t1.so --version-script=%t.ver -o %t1.so
+// RUN: ld.lld %t.o %t1.so -o %t
+// RUN: llvm-readobj -t %t | FileCheck %s
+
+.global _start
+_start:
+  leaq foo, %rax
+
+// CHECK: Name: foo (
+// CHECK: Value:
+// CHECK: Size: 8
Index: ELF/Relocations.cpp
===================================================================
--- ELF/Relocations.cpp
+++ ELF/Relocations.cpp
@@ -52,6 +52,7 @@
 #include "Thunks.h"
 #include "lld/Common/Memory.h"
 #include "lld/Common/Strings.h"
+#include "llvm/ADT/SmallSet.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
@@ -432,22 +433,23 @@
 //
 // If two or more symbols are at the same offset, and at least one of
 // them are copied by a copy relocation, all of them need to be copied.
-// Otherwise, they would refer different places at runtime.
+// Otherwise, they would refer to different places at runtime.
 template <class ELFT>
-static std::vector<SharedSymbol *> getSymbolsAt(SharedSymbol &SS) {
+static SmallSet<SharedSymbol *, 4> getSymbolsAt(SharedSymbol &SS) {
   typedef typename ELFT::Sym Elf_Sym;
 
   SharedFile<ELFT> &File = SS.getFile<ELFT>();
 
-  std::vector<SharedSymbol *> Ret;
+  // Use a set to deduplicate symbols.
+  SmallSet<SharedSymbol *, 4> Ret;
   for (const Elf_Sym &S : File.getGlobalELFSyms()) {
     if (S.st_shndx == SHN_UNDEF || S.st_shndx == SHN_ABS ||
         S.st_value != SS.Value)
       continue;
     StringRef Name = check(S.getName(File.getStringTable()));
     Symbol *Sym = Symtab->find(Name);
     if (auto *Alias = dyn_cast_or_null<SharedSymbol>(Sym))
-      Ret.push_back(Alias);
+      Ret.insert(Alias);
   }
   return Ret;
 }


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