[ELF] Set `referenced` bit of Undefined created by BitcodeFile
D64136 and D65584, while fixing STB_WEAK issues and improving our
compatibility with ld.bfd, can cause another STB_WEAK problem related to
LTO:
If %tundef.o has an undefined reference on f,
and %tweakundef.o has a weak undefined reference on f,
%tdef.o has a definition of f
```
ld.lld %tundef.o %tweakundef.o --start-lib %tdef.o --end-lib
```
1) `%tundef.o` doesn't set the `referenced` bit.
2) `%weakundef.o` changes the binding from STB_GLOBAL to STB_WEAK
3) `%tdef.o` is not fetched because the binding is weak.
Step (1) is incorrect. This patch sets the `referenced` bit of Undefined
created by bitcode files.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D66992
git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@370437 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/ELF/InputFiles.cpp b/ELF/InputFiles.cpp
index 4d2533f..71f28f4 100644
--- a/ELF/InputFiles.cpp
+++ b/ELF/InputFiles.cpp
@@ -1478,7 +1478,9 @@
Undefined newSym(&f, name, binding, visibility, type);
if (canOmitFromDynSym)
newSym.exportDynamic = false;
- return symtab->addSymbol(newSym);
+ Symbol *ret = symtab->addSymbol(newSym);
+ ret->referenced = true;
+ return ret;
}
if (objSym.isCommon())
diff --git a/test/ELF/lto/Inputs/undef.ll b/test/ELF/lto/Inputs/undef.ll
new file mode 100644
index 0000000..48a4b69
--- /dev/null
+++ b/test/ELF/lto/Inputs/undef.ll
@@ -0,0 +1,4 @@
+target triple = "x86_64-unknown-linux-gnu"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+declare void @foo()
diff --git a/test/ELF/lto/undef-weak-lazy.ll b/test/ELF/lto/undef-weak-lazy.ll
new file mode 100644
index 0000000..5ce03ff
--- /dev/null
+++ b/test/ELF/lto/undef-weak-lazy.ll
@@ -0,0 +1,23 @@
+; REQUIRES: x86
+; RUN: llvm-as %S/Inputs/undef.ll -o %tundef.o
+; RUN: llvm-as %s -o %tweakundef.o
+; RUN: llvm-as %S/Inputs/archive-3.ll -o %tdef.o
+
+;; Test that the lazy bitcode %tdef.o is fetched.
+; RUN: ld.lld %tundef.o --start-lib %tdef.o --end-lib -shared -o %t.so
+; RUN: llvm-nm %t.so | FileCheck %s
+
+;; Test %tweakundef.o does not change STB_GLOBAL to STB_WEAK.
+; RUN: ld.lld %tundef.o %tweakundef.o --start-lib %tdef.o --end-lib -shared -o %t.so
+; RUN: llvm-nm %t.so | FileCheck %s
+
+;; %tweakundef.o does not fetch %tdef.o but %tundef.o does.
+; RUN: ld.lld --start-lib %tdef.o --end-lib %tweakundef.o %tundef.o -shared -o %t.so
+; RUN: llvm-nm %t.so | FileCheck %s
+
+; CHECK: T foo
+
+target triple = "x86_64-unknown-linux-gnu"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+declare extern_weak void @foo()
