[PATCH] D23405: [ELF] Do not add start and end symbols in case they are defined in linker script

[Eugene Leviant via llvm-commits]

evgeny777 updated this revision to Diff 67816.
evgeny777 added a comment.

Simplified


https://reviews.llvm.org/D23405

Files:
  ELF/Writer.cpp
  test/ELF/linkerscript/linkerscript-start-end.s

Index: test/ELF/linkerscript/linkerscript-start-end.s
===================================================================
--- test/ELF/linkerscript/linkerscript-start-end.s
+++ 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
Index: ELF/Writer.cpp
===================================================================
--- ELF/Writer.cpp
+++ ELF/Writer.cpp
@@ -521,6 +521,13 @@
   return Symtab<ELFT>::X->addSynthetic(Name, Sec, Val);
 }
 
+template <class ELFT>
+static void addRequiredSynthetic(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 @@
   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);
+      addRequiredSynthetic(Start, OS, 0);
+      addRequiredSynthetic(End, OS, DefinedSynthetic<ELFT>::SectionEnd);
     } else {
       addOptionalSynthetic(Start, (OutputSectionBase<ELFT> *)nullptr, 0);
       addOptionalSynthetic(End, (OutputSectionBase<ELFT> *)nullptr, 0);


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