ELF: Implement basic support for --version-script.
This patch only implements support for version scripts of the form:
{ [ global: symbol1; symbol2; [...]; symbolN; ] local: *; };
No wildcards are supported, other than for the local entry. Symbol versioning
is also not supported.
It works by introducing a new Symbol flag which tracks whether a symbol
appears in the global section of a version script.
This patch also simplifies the logic in SymbolBody::isPreemptible(), and
teaches it to handle the case where symbols with default visibility in DSOs
do not appear in the dynamic symbol table because of a version script.
Fixes PR27482.
Differential Revision: http://reviews.llvm.org/D19430
llvm-svn: 267208
diff --git a/lld/ELF/Symbols.cpp b/lld/ELF/Symbols.cpp
index 206a523..1b82348 100644
--- a/lld/ELF/Symbols.cpp
+++ b/lld/ELF/Symbols.cpp
@@ -115,31 +115,26 @@
if (isLocal())
return false;
+ // Shared symbols resolve to the definition in the DSO.
if (isShared())
return true;
- if (Backref->Visibility != STV_DEFAULT)
- return false;
-
- if (isUndefined()) {
- if (!isWeak())
- return true;
-
- // Ideally the static linker should see a definition for every symbol, but
- // shared object are normally allowed to have undefined references that the
- // static linker never sees a definition for.
- if (Config->Shared)
- return true;
-
- // Otherwise, just resolve to 0.
- return false;
- }
-
+ // That's all that can be preempted in a non-DSO.
if (!Config->Shared)
return false;
+
+ // Undefined symbols in DSOs can only be preempted if they are strong.
+ // Weak symbols just resolve to zero.
+ if (isUndefined())
+ return !isWeak();
+
+ // -Bsymbolic means that not even default visibility symbols can be preempted.
if (Config->Bsymbolic || (Config->BsymbolicFunctions && isFunc()))
return false;
- return true;
+
+ // Only default visibility symbols that appear in the dynamic symbol table can
+ // be preempted.
+ return Backref->Visibility == STV_DEFAULT && Backref->includeInDynsym();
}
template <class ELFT>
@@ -328,7 +323,7 @@
bool Symbol::includeInDynsym() const {
if (Visibility != STV_DEFAULT && Visibility != STV_PROTECTED)
return false;
- return ExportDynamic || Body->isShared();
+ return (ExportDynamic && VersionScriptGlobal) || Body->isShared();
}
template uint32_t SymbolBody::template getVA<ELF32LE>(uint32_t) const;
