[lld] r325152 - Make --export-dynamic-symbol to add undefined symbols even if --export-dynamic is given.

[Rui Ueyama via llvm-commits]

Author: ruiu
Date: Wed Feb 14 10:38:33 2018
New Revision: 325152

URL: http://llvm.org/viewvc/llvm-project?rev=325152&view=rev
Log:
Make --export-dynamic-symbol to add undefined symbols even if --export-dynamic is given.

This patch addresses a minor compatibility issue with GNU linkers.
Previously, --export-dynamic-symbol is completely ignored if you
pass --export-dynamic together.

Differential Revision: https://reviews.llvm.org/D43266

Modified:
    lld/trunk/ELF/Driver.cpp
    lld/trunk/test/ELF/export-dynamic-symbol.s

Modified: lld/trunk/ELF/Driver.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Driver.cpp?rev=325152&r1=325151&r2=325152&view=diff
==============================================================================
--- lld/trunk/ELF/Driver.cpp (original)
+++ lld/trunk/ELF/Driver.cpp Wed Feb 14 10:38:33 2018
@@ -803,13 +803,18 @@ void LinkerDriver::readConfigs(opt::Inpu
       if (Optional<MemoryBufferRef> Buffer = readFile(Arg->getValue()))
         readDynamicList(*Buffer);
 
-    for (auto *Arg : Args.filtered(OPT_export_dynamic_symbol)) {
+    for (auto *Arg : Args.filtered(OPT_export_dynamic_symbol))
       Config->DynamicList.push_back(
           {Arg->getValue(), /*IsExternCpp*/ false, /*HasWildcard*/ false});
-      Config->Undefined.push_back(Arg->getValue());
-    }
   }
 
+  // If --export-dynamic-symbol=foo is given and symbol foo is defined in
+  // an object file in an archive file, that object file should be pulled
+  // out and linked. (It doesn't have to behave like that from technical
+  // point of view, but this is needed for compatibility with GNU.)
+  for (auto *Arg : Args.filtered(OPT_export_dynamic_symbol))
+    Config->Undefined.push_back(Arg->getValue());
+
   for (auto *Arg : Args.filtered(OPT_version_script))
     if (Optional<MemoryBufferRef> Buffer = readFile(Arg->getValue()))
       readVersionScript(*Buffer);

Modified: lld/trunk/test/ELF/export-dynamic-symbol.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/export-dynamic-symbol.s?rev=325152&r1=325151&r2=325152&view=diff
==============================================================================
--- lld/trunk/test/ELF/export-dynamic-symbol.s (original)
+++ lld/trunk/test/ELF/export-dynamic-symbol.s Wed Feb 14 10:38:33 2018
@@ -3,11 +3,14 @@
 # RUN: rm -f %t.a
 # RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %S/Inputs/archive2.s -o %t1.o
 # RUN: llvm-ar rcs %t.a %t1.o
-
 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t2.o
+
 # RUN: ld.lld -shared -o %t.so --export-dynamic-symbol foo %t.a %t2.o
+# RUN: llvm-readelf -dyn-symbols %t.so | FileCheck %s
 
+# RUN: ld.lld -shared -o %t.so --export-dynamic --export-dynamic-symbol foo %t.a %t2.o
 # RUN: llvm-readelf -dyn-symbols %t.so | FileCheck %s
+
 # CHECK: foo
 
 .global _start