From a5c8a685356a5c5e956723429f7c2c39f8fbcd37 Mon Sep 17 00:00:00 2001
From: Eugene Leviant <evgeny.leviant@gmail.com>
Date: Mon, 15 Aug 2016 07:24:20 +0000
Subject: [PATCH] [ELF] Do not add start and end symbols in case they are
 already defined

llvm-svn: 278657
---
 lld/ELF/Writer.cpp                                 | 12 +++++++++---
 lld/test/ELF/linkerscript/linkerscript-start-end.s | 16 ++++++++++++++++
 2 files changed, 25 insertions(+), 3 deletions(-)
 create mode 100644 lld/test/ELF/linkerscript/linkerscript-start-end.s

diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index 416ef76..108ca54 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -521,6 +521,13 @@ static Symbol *addOptionalSynthetic(StringRef Name,
   return Symtab<ELFT>::X->addSynthetic(Name, Sec, Val);
 }
 
+template <class ELFT>
+static void addSynthetic(StringRef Name, OutputSectionBase<ELFT> *Sec,
+                                 typename ELFT::uint Val) {
+  SymbolBody *S = Symtab<ELFT>::X->find(Name);
+  if (!S || S->isUndefined() || S->isShared())
+    Symtab<ELFT>::X->addSynthetic(Name, Sec, Val);
+}
 // The beginning and the ending of .rel[a].plt section are marked
 // with __rel[a]_iplt_{start,end} symbols if it is a statically linked
 // executable. The runtime needs these symbols in order to resolve
@@ -856,9 +863,8 @@ template <class ELFT> void Writer<ELFT>::addStartEndSymbols() {
   auto Define = [&](StringRef Start, StringRef End,
                     OutputSectionBase<ELFT> *OS) {
     if (OS) {
-      Symtab<ELFT>::X->addSynthetic(Start, OS, 0);
-      Symtab<ELFT>::X->addSynthetic(End, OS,
-                                    DefinedSynthetic<ELFT>::SectionEnd);
+      addSynthetic(Start, OS, 0);
+      addSynthetic(End, OS, DefinedSynthetic<ELFT>::SectionEnd);
     } else {
       addOptionalSynthetic(Start, (OutputSectionBase<ELFT> *)nullptr, 0);
       addOptionalSynthetic(End, (OutputSectionBase<ELFT> *)nullptr, 0);
diff --git a/lld/test/ELF/linkerscript/linkerscript-start-end.s b/lld/test/ELF/linkerscript/linkerscript-start-end.s
new file mode 100644
index 0000000..b68606a
--- /dev/null
+++ b/lld/test/ELF/linkerscript/linkerscript-start-end.s
@@ -0,0 +1,16 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+# RUN: echo "SECTIONS { \
+# RUN:      .init_array : { \
+# RUN:        __init_array_start = .; \
+# RUN:        *(.init_array) \
+# RUN:        __init_array_end = .; } }" > %t.script
+# RUN: ld.lld %t.o -script %t.script -o %t 2>&1
+
+.globl _start
+.text
+_start:
+  nop
+
+.section .init_array, "aw"
+  .quad 0
-- 
2.7.4