[lld] r290122 - [ELF] - Implemented --retain-symbols-file option
George Rimar via llvm-commits
llvm-commits at lists.llvm.org
Mon Dec 19 10:00:52 PST 2016
Author: grimar
Date: Mon Dec 19 12:00:52 2016
New Revision: 290122
URL: http://llvm.org/viewvc/llvm-project?rev=290122&view=rev
Log:
[ELF] - Implemented --retain-symbols-file option
--retain-symbols-file=filename
Retain only the symbols listed in the file filename, discarding all others.
filename is simply a flat file, with one symbol name per line. This option
is especially useful in environments (such as VxWorks) where a large global
symbol table is accumulated gradually, to conserve run-time memory.
Note: though documentation says "--retain-symbols-file does not discard
undefined symbols, or symbols needed for relocations.", both bfd and gold
do that, and this patch too, like testcase show.
Differential revision: https://reviews.llvm.org/D27716
Added:
lld/trunk/test/ELF/retain-symbols-file.s
Modified:
lld/trunk/ELF/Config.h
lld/trunk/ELF/Driver.cpp
lld/trunk/ELF/Options.td
lld/trunk/ELF/Writer.cpp
Modified: lld/trunk/ELF/Config.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Config.h?rev=290122&r1=290121&r2=290122&view=diff
==============================================================================
--- lld/trunk/ELF/Config.h (original)
+++ lld/trunk/ELF/Config.h Mon Dec 19 12:00:52 2016
@@ -12,6 +12,7 @@
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/StringSet.h"
#include "llvm/Support/ELF.h"
#include <vector>
@@ -33,8 +34,8 @@ enum ELFKind {
// For --build-id.
enum class BuildIdKind { None, Fast, Md5, Sha1, Hexstring, Uuid };
-// For --discard-{all,locals,none}.
-enum class DiscardPolicy { Default, All, Locals, None };
+// For --discard-{all,locals,none} and --retain-symbols-file.
+enum class DiscardPolicy { Default, All, Locals, RetainFile, None };
// For --strip-{all,debug}.
enum class StripPolicy { None, All, Debug };
@@ -83,6 +84,7 @@ struct Configuration {
llvm::StringRef OutputFile;
llvm::StringRef SoName;
llvm::StringRef Sysroot;
+ llvm::StringSet<> RetainSymbolsFile;
std::string RPath;
std::vector<VersionDefinition> VersionDefinitions;
std::vector<llvm::StringRef> AuxiliaryList;
Modified: lld/trunk/ELF/Driver.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Driver.cpp?rev=290122&r1=290121&r2=290122&view=diff
==============================================================================
--- lld/trunk/ELF/Driver.cpp (original)
+++ lld/trunk/ELF/Driver.cpp Mon Dec 19 12:00:52 2016
@@ -478,16 +478,35 @@ static SortSectionPolicy getSortKind(opt
return SortSectionPolicy::Default;
}
+static std::vector<StringRef> getLines(MemoryBufferRef MB) {
+ std::vector<StringRef> Ret;
+ SmallVector<StringRef, 0> Arr;
+ MB.getBuffer().split(Arr, '\n');
+ for (StringRef S : Arr) {
+ S = S.trim();
+ if (!S.empty())
+ Ret.push_back(S);
+ }
+ return Ret;
+}
+
// Parse the --symbol-ordering-file argument. File has form:
// symbolName1
// [...]
// symbolNameN
static void parseSymbolOrderingList(MemoryBufferRef MB) {
unsigned I = 0;
- SmallVector<StringRef, 0> Arr;
- MB.getBuffer().split(Arr, '\n');
- for (StringRef S : Arr)
- Config->SymbolOrderingFile.insert({S.trim(), I++});
+ for (StringRef S : getLines(MB))
+ Config->SymbolOrderingFile.insert({S, I++});
+}
+
+// Parse the --retain-symbols-file argument. File has form:
+// symbolName1
+// [...]
+// symbolNameN
+static void parseRetainSymbolsList(MemoryBufferRef MB) {
+ for (StringRef S : getLines(MB))
+ Config->RetainSymbolsFile.insert(S);
}
// Initializes Config members by the command line options.
@@ -636,6 +655,14 @@ void LinkerDriver::readConfigs(opt::Inpu
if (Optional<MemoryBufferRef> Buffer = readFile(Arg->getValue()))
parseSymbolOrderingList(*Buffer);
+ // If --retain-symbol-file is used, we'll retail only the symbols listed in
+ // the file and discard all others.
+ if (auto *Arg = Args.getLastArg(OPT_retain_symbols_file)) {
+ Config->Discard = DiscardPolicy::RetainFile;
+ if (Optional<MemoryBufferRef> Buffer = readFile(Arg->getValue()))
+ parseRetainSymbolsList(*Buffer);
+ }
+
for (auto *Arg : Args.filtered(OPT_export_dynamic_symbol))
Config->VersionScriptGlobals.push_back(
{Arg->getValue(), /*IsExternCpp*/ false, /*HasWildcard*/ false});
Modified: lld/trunk/ELF/Options.td
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Options.td?rev=290122&r1=290121&r2=290122&view=diff
==============================================================================
--- lld/trunk/ELF/Options.td (original)
+++ lld/trunk/ELF/Options.td Mon Dec 19 12:00:52 2016
@@ -176,6 +176,9 @@ def rpath: S<"rpath">, HelpText<"Add a D
def relocatable: F<"relocatable">, HelpText<"Create relocatable object file">;
+def retain_symbols_file: J<"retain-symbols-file=">, MetaVarName<"<file>">,
+ HelpText<"Retain only the symbols listed in the file">;
+
def script: S<"script">, HelpText<"Read linker script">;
def section_start: S<"section-start">, MetaVarName<"<address>">,
@@ -269,6 +272,7 @@ def alias_o_output: Joined<["--"], "outp
def alias_o_output2 : Separate<["--"], "output">, Alias<o>;
def alias_pie_pic_executable: F<"pic-executable">, Alias<pie>;
def alias_relocatable_r: Flag<["-"], "r">, Alias<relocatable>;
+def alias_retain_symbols_file: S<"retain-symbols-file">, Alias<retain_symbols_file>;
def alias_rpath_R: JoinedOrSeparate<["-"], "R">, Alias<rpath>;
def alias_rpath_rpath: J<"rpath=">, Alias<rpath>;
def alias_script_T: JoinedOrSeparate<["-"], "T">, Alias<script>;
Modified: lld/trunk/ELF/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=290122&r1=290121&r2=290122&view=diff
==============================================================================
--- lld/trunk/ELF/Writer.cpp (original)
+++ lld/trunk/ELF/Writer.cpp Mon Dec 19 12:00:52 2016
@@ -420,6 +420,12 @@ template <class ELFT> static bool includ
if (!B.isLocal() && !B.symbol()->IsUsedInRegularObj)
return false;
+ // If --retain-symbols-file is given, we'll keep only symbols listed in that
+ // file.
+ if (Config->Discard == DiscardPolicy::RetainFile &&
+ !Config->RetainSymbolsFile.count(B.getName()))
+ return false;
+
if (auto *D = dyn_cast<DefinedRegular<ELFT>>(&B)) {
// Always include absolute symbols.
if (!D->Section)
Added: lld/trunk/test/ELF/retain-symbols-file.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/retain-symbols-file.s?rev=290122&view=auto
==============================================================================
--- lld/trunk/test/ELF/retain-symbols-file.s (added)
+++ lld/trunk/test/ELF/retain-symbols-file.s Mon Dec 19 12:00:52 2016
@@ -0,0 +1,44 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t
+# RUN: echo "bar" > %t_retain.txt
+# RUN: echo "foo" >> %t_retain.txt
+# RUN: ld.lld -shared --retain-symbols-file=%t_retain.txt %t -o %t2
+# RUN: llvm-readobj -s -sd -t %t2 | FileCheck %s
+
+## Check separate form.
+# RUN: ld.lld -shared --retain-symbols-file %t_retain.txt %t -o %t2
+# RUN: llvm-readobj -s -sd -t %t2 | FileCheck %s
+
+# CHECK: Symbols [
+# CHECK-NEXT: Symbol {
+# CHECK-NEXT: Name: (0)
+# CHECK: Symbol {
+# CHECK-NEXT: Name: bar
+# CHECK: Symbol {
+# CHECK-NEXT: Name: foo
+# CHECK-NOT: Symbol
+
+.text
+.globl _start
+_start:
+call zed at PLT
+call und at PLT
+
+.globl foo
+.type foo, at function
+foo:
+retq
+
+.globl bar
+.type bar, at function
+bar:
+retq
+
+.globl zed
+.type zed, at function
+zed:
+retq
+
+.type loc, at function
+loc:
+retq
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