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authorDenis Protivensky <dprotivensky@accesssoftek.com>2015-10-05 09:43:57 +0000
committerDenis Protivensky <dprotivensky@accesssoftek.com>2015-10-05 09:43:57 +0000
commit22220d5d5f97c1e3192a42a81dfae76a593bc70b (patch)
tree790dd013e93b22d2113ed0f2f8877d97664a74ee
parent6967527441a6daa56027822ab9419dfb882e9780 (diff)
downloadbcm5719-llvm-22220d5d5f97c1e3192a42a81dfae76a593bc70b.tar.gz
bcm5719-llvm-22220d5d5f97c1e3192a42a81dfae76a593bc70b.zip
[ELF2] Add --undefined option
Add symbol specified with -u as undefined which may cause additional object files from archives to be linked into the resulting binary. Differential Revision: http://reviews.llvm.org/D13345 llvm-svn: 249295
-rw-r--r--lld/ELF/Driver.cpp3
-rw-r--r--lld/ELF/Options.td4
-rw-r--r--lld/ELF/SymbolTable.cpp25
-rw-r--r--lld/ELF/SymbolTable.h3
-rw-r--r--lld/ELF/Symbols.h10
-rw-r--r--lld/ELF/Writer.cpp6
-rw-r--r--lld/test/elf2/undefined-opt.s51
7 files changed, 96 insertions, 6 deletions
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index 7375b74565a..078382c0c4b 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -157,6 +157,9 @@ void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
if (Symtab.getObjectFiles().empty())
error("no input files.");
+ for (auto *Arg : Args.filtered(OPT_undefined))
+ Symtab.addUndefinedSym(Arg->getValue());
+
// Write the result.
const ELFFileBase *FirstObj = Symtab.getFirstELF();
switch (FirstObj->getELFKind()) {
diff --git a/lld/ELF/Options.td b/lld/ELF/Options.td
index 284c2abe91e..a9b0cf84d1c 100644
--- a/lld/ELF/Options.td
+++ b/lld/ELF/Options.td
@@ -61,6 +61,9 @@ def soname : Joined<["-"], "soname=">,
def sysroot : Joined<["--"], "sysroot=">,
HelpText<"Set the system root">;
+def undefined : Joined<["--"], "undefined=">,
+ HelpText<"Force undefined symbol during linking">;
+
def whole_archive : Flag<["--"], "whole-archive">,
HelpText<"Force load of all members in a static library">;
@@ -78,6 +81,7 @@ def alias_l__library : Joined<["--"], "library=">, Alias<l>;
def alias_rpath_rpath : Joined<["-"], "rpath=">, Alias<rpath>;
def alias_soname_h : Separate<["-"], "h">, Alias<soname>;
def alias_soname_soname : Separate<["-"], "soname">, Alias<soname>;
+def alias_undefined_u : Separate<["-"], "u">, Alias<undefined>;
// Options listed below are silently ignored now.
def O3 : Flag<["-"], "O3">;
diff --git a/lld/ELF/SymbolTable.cpp b/lld/ELF/SymbolTable.cpp
index 1e527629c5e..14fcb3548a8 100644
--- a/lld/ELF/SymbolTable.cpp
+++ b/lld/ELF/SymbolTable.cpp
@@ -70,6 +70,29 @@ static TargetInfo *createTarget(uint16_t EMachine) {
error("Unknown target machine");
}
+void SymbolTable::addUndefinedSym(StringRef Name) {
+ switch (getFirstELF()->getELFKind()) {
+ case ELF32LEKind:
+ addUndefinedSym<ELF32LE>(Name);
+ break;
+ case ELF32BEKind:
+ addUndefinedSym<ELF32BE>(Name);
+ break;
+ case ELF64LEKind:
+ addUndefinedSym<ELF64LE>(Name);
+ break;
+ case ELF64BEKind:
+ addUndefinedSym<ELF64BE>(Name);
+ break;
+ }
+}
+
+template <class ELFT> void SymbolTable::addUndefinedSym(StringRef Name) {
+ Undefined<ELFT>::SyntheticOptional.setVisibility(STV_HIDDEN);
+ resolve<ELFT>(new (Alloc)
+ Undefined<ELFT>(Name, Undefined<ELFT>::SyntheticOptional));
+}
+
template <class ELFT>
void SymbolTable::addSyntheticSym(StringRef Name, OutputSection<ELFT> &Section,
typename ELFFile<ELFT>::uintX_t Value) {
@@ -94,7 +117,7 @@ template <class ELFT> void SymbolTable::init(uint16_t EMachine) {
return;
EntrySym = new (Alloc) Undefined<ELFT>(
Config->Entry.empty() ? Target->getDefaultEntry() : Config->Entry,
- Undefined<ELFT>::Synthetic);
+ Undefined<ELFT>::SyntheticRequired);
resolve<ELFT>(EntrySym);
// In the assembly for 32 bit x86 the _GLOBAL_OFFSET_TABLE_ symbol is magical
diff --git a/lld/ELF/SymbolTable.h b/lld/ELF/SymbolTable.h
index c451a2d1b73..b545198e47b 100644
--- a/lld/ELF/SymbolTable.h
+++ b/lld/ELF/SymbolTable.h
@@ -61,6 +61,8 @@ public:
return EntrySym->getReplacement();
}
+ void addUndefinedSym(StringRef Name);
+
template <class ELFT>
void addSyntheticSym(StringRef Name, OutputSection<ELFT> &Section,
typename llvm::object::ELFFile<ELFT>::uintX_t Value);
@@ -73,6 +75,7 @@ private:
void addELFFile(ELFFileBase *File);
void addLazy(Lazy *New);
void addMemberFile(Lazy *Body);
+ template <class ELFT> void addUndefinedSym(StringRef Name);
template <class ELFT> void init(uint16_t EMachine);
template <class ELFT> void resolve(SymbolBody *Body);
diff --git a/lld/ELF/Symbols.h b/lld/ELF/Symbols.h
index fd928baac6c..39e3d31b4ae 100644
--- a/lld/ELF/Symbols.h
+++ b/lld/ELF/Symbols.h
@@ -53,7 +53,6 @@ public:
bool isWeak() const { return IsWeak; }
bool isUndefined() const { return SymbolKind == UndefinedKind; }
bool isDefined() const { return SymbolKind <= DefinedLast; }
- bool isStrongUndefined() const { return !IsWeak && isUndefined(); }
bool isCommon() const { return SymbolKind == DefinedCommonKind; }
bool isLazy() const { return SymbolKind == LazyKind; }
bool isShared() const { return SymbolKind == SharedKind; }
@@ -235,7 +234,8 @@ template <class ELFT> class Undefined : public ELFSymbolBody<ELFT> {
typedef typename Base::Elf_Sym Elf_Sym;
public:
- static Elf_Sym Synthetic;
+ static Elf_Sym SyntheticRequired;
+ static Elf_Sym SyntheticOptional;
Undefined(StringRef N, const Elf_Sym &Sym)
: ELFSymbolBody<ELFT>(Base::UndefinedKind, N, Sym) {}
@@ -243,10 +243,14 @@ public:
static bool classof(const SymbolBody *S) {
return S->kind() == Base::UndefinedKind;
}
+
+ bool canKeepUndefined() const { return &this->Sym == &SyntheticOptional; }
};
template <class ELFT>
-typename Undefined<ELFT>::Elf_Sym Undefined<ELFT>::Synthetic;
+typename Undefined<ELFT>::Elf_Sym Undefined<ELFT>::SyntheticRequired;
+template <class ELFT>
+typename Undefined<ELFT>::Elf_Sym Undefined<ELFT>::SyntheticOptional;
template <class ELFT> class SharedSymbol : public Defined<ELFT> {
typedef Defined<ELFT> Base;
diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index cd9b760bb23..c7dbafe86ed 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -334,8 +334,10 @@ template <class ELFT> void Writer<ELFT>::createSections() {
for (auto &P : Symtab.getSymbols()) {
StringRef Name = P.first;
SymbolBody *Body = P.second->Body;
- if (Body->isStrongUndefined())
- reportUndefined<ELFT>(Symtab, *Body);
+ if (auto *U = dyn_cast<Undefined<ELFT>>(Body)) {
+ if (!U->isWeak() && !U->canKeepUndefined())
+ reportUndefined<ELFT>(Symtab, *Body);
+ }
if (auto *C = dyn_cast<DefinedCommon<ELFT>>(Body))
CommonSymbols.push_back(C);
diff --git a/lld/test/elf2/undefined-opt.s b/lld/test/elf2/undefined-opt.s
new file mode 100644
index 00000000000..5fcf6dc3c8c
--- /dev/null
+++ b/lld/test/elf2/undefined-opt.s
@@ -0,0 +1,51 @@
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux \
+# RUN: %p/Inputs/abs.s -o %tabs.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux \
+# RUN: %p/Inputs/shared.s -o %tshared.o
+# RUN: rm -f %tar.a
+# RUN: llvm-ar rcs %tar.a %tabs.o %tshared.o
+# REQUIRES: x86
+
+# Symbols from the archive are not in if not needed
+# RUN: lld -flavor gnu2 -o %t1 %t.o %tar.a
+# RUN: llvm-readobj --symbols %t1 | FileCheck --check-prefix=NO-UNDEFINED %s
+# NO-UNDEFINED: Symbols [
+# NO-UNDEFINED-NOT: Name: abs
+# NO-UNDEFINED-NOT: Name: big
+# NO-UNDEFINED-NOT: Name: bar
+# NO-UNDEFINED-NOT: Name: zed
+# NO-UNDEFINED: ]
+
+# Symbols from the archive are in if needed, but only from the
+# containing object file
+# RUN: lld -flavor gnu2 -o %t2 %t.o %tar.a -u bar
+# RUN: llvm-readobj --symbols %t2 | FileCheck --check-prefix=ONE-UNDEFINED %s
+# ONE-UNDEFINED: Symbols [
+# ONE-UNDEFINED-NOT: Name: abs
+# ONE-UNDEFINED-NOT: Name: big
+# ONE-UNDEFINED: Name: bar
+# ONE-UNDEFINED: Name: zed
+# ONE-UNDEFINED: ]
+
+# Use the option couple of times, both short and long forms
+# RUN: lld -flavor gnu2 -o %t3 %t.o %tar.a -u bar --undefined=abs
+# RUN: llvm-readobj --symbols %t3 | FileCheck --check-prefix=TWO-UNDEFINED %s
+# TWO-UNDEFINED: Symbols [
+# TWO-UNDEFINED: Name: abs
+# TWO-UNDEFINED: Name: big
+# TWO-UNDEFINED: Name: bar
+# TWO-UNDEFINED: Name: zed
+# TWO-UNDEFINED: ]
+
+# Added undefined symbol may be left undefined without error, but
+# shouldn't show up in the dynamic table.
+# RUN: lld -flavor gnu2 -shared -o %t4 %t.o %tar.a -u unknown
+# RUN: llvm-readobj --dyn-symbols %t4 | \
+# RUN: FileCheck --check-prefix=UNK-UNDEFINED-SO %s
+# UNK-UNDEFINED-SO: DynamicSymbols [
+# UNK-UNDEFINED-SO-NOT: Name: unknown
+# UNK-UNDEFINED-SO: ]
+
+.globl _start;
+_start:
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