If a .syms file is available alongside a sanitizer runtime, pass it to the

linker via --dynamic-list instead of using --export-dynamic. This reduces the
size of the dynamic symbol table, and thus of the binary (in some cases by up
to ~30%).


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177783 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Driver/CC1Options.td

@@ -282,8 +282,6 @@ def plugin_arg : JoinedAndSeparate<["-"], "plugin-arg-">,
     HelpText<"Pass <arg> to plugin <name>">;
 def add_plugin : Separate<["-"], "add-plugin">, MetaVarName<"<name>">,
   HelpText<"Use the named plugin action in addition to the default action">;
-def resource_dir : Separate<["-"], "resource-dir">,
-  HelpText<"The directory which holds the compiler resource files">;
 def version : Flag<["-"], "version">,
   HelpText<"Print the compiler version">;
 def ast_dump_filter : Separate<["-"], "ast-dump-filter">,

include/clang/Driver/Options.td

@@ -1016,6 +1016,11 @@ def rewrite_objc : Flag<["-"], "rewrite-objc">, Flags<[DriverOption,CC1Option]>,
 def rewrite_legacy_objc : Flag<["-"], "rewrite-legacy-objc">, Flags<[DriverOption]>,
   HelpText<"Rewrite Legacy Objective-C source to C++">;
 def rdynamic : Flag<["-"], "rdynamic">;
+def resource_dir : Separate<["-"], "resource-dir">,
+  Flags<[DriverOption, CC1Option, HelpHidden]>,
+  HelpText<"The directory which holds the compiler resource files">;
+def resource_dir_EQ : Joined<["-"], "resource-dir=">, Flags<[DriverOption]>,
+  Alias<resource_dir>;
 def rpath : Separate<["-"], "rpath">, Flags<[LinkerInput]>;
 def rtlib_EQ : Joined<["-", "--"], "rtlib=">;
 def r : Flag<["-"], "r">;

lib/Driver/Driver.cpp

@@ -287,7 +287,9 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
   // ccc-install-dir) can change 'Dir'.
   StringRef ClangResourceDir(CLANG_RESOURCE_DIR);
   SmallString<128> P(Dir);
-  if (!ClangResourceDir.empty())
+  if (const Arg *A = Args->getLastArg(options::OPT_resource_dir))
+    P = A->getValue();
+  else if (!ClangResourceDir.empty())
     llvm::sys::path::append(P, ClangResourceDir);
   else
     llvm::sys::path::append(P, "..", "lib", "clang", CLANG_VERSION_STRING);

lib/Driver/Tools.cpp

@@ -1575,7 +1575,8 @@ SanitizerArgs::SanitizerArgs(const Driver &D, const ArgList &Args)
 
 static void addSanitizerRTLinkFlagsLinux(
     const ToolChain &TC, const ArgList &Args, ArgStringList &CmdArgs,
-    const StringRef Sanitizer, bool BeforeLibStdCXX) {
+    const StringRef Sanitizer, bool BeforeLibStdCXX,
+    bool ExportSymbols = true) {
   // Sanitizer runtime is located in the Linux library directory and
   // has name "libclang_rt.<Sanitizer>-<ArchName>.a".
   SmallString<128> LibSanitizer(TC.getDriver().ResourceDir);
@@ -1599,7 +1600,17 @@ static void addSanitizerRTLinkFlagsLinux(
 
   CmdArgs.push_back("-lpthread");
   CmdArgs.push_back("-ldl");
-  CmdArgs.push_back("-export-dynamic");
+
+  // If possible, use a dynamic symbols file to export the symbols from the
+  // runtime library. If we can't do so, use -export-dynamic instead to export
+  // all symbols from the binary.
+  if (ExportSymbols) {
+    if (llvm::sys::fs::exists(LibSanitizer + ".syms"))
+      CmdArgs.push_back(
+          Args.MakeArgString("--dynamic-list=" + LibSanitizer + ".syms"));
+    else
+      CmdArgs.push_back("-export-dynamic");
+  }
 }
 
 /// If AddressSanitizer is enabled, add appropriate linker flags (Linux).
@@ -1666,7 +1677,7 @@ static void addUbsanRTLinux(const ToolChain &TC, const ArgList &Args,
   // Need a copy of sanitizer_common. This could come from another sanitizer
   // runtime; if we're not including one, include our own copy.
   if (!HasOtherSanitizerRt)
-    addSanitizerRTLinkFlagsLinux(TC, Args, CmdArgs, "san", true);
+    addSanitizerRTLinkFlagsLinux(TC, Args, CmdArgs, "san", true, false);
 
   addSanitizerRTLinkFlagsLinux(TC, Args, CmdArgs, "ubsan", false);
 

test/Driver/sanitizer-ld.c

@@ -2,6 +2,7 @@
 
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -target i386-unknown-linux -fsanitize=address \
+// RUN:     -resource-dir=%S/Inputs/resource_dir \
 // RUN:     --sysroot=%S/Inputs/basic_linux_tree \
 // RUN:   | FileCheck --check-prefix=CHECK-ASAN-LINUX %s
 //
@@ -10,10 +11,12 @@
 // CHECK-ASAN-LINUX: libclang_rt.asan-i386.a"
 // CHECK-ASAN-LINUX: "-lpthread"
 // CHECK-ASAN-LINUX: "-ldl"
-// CHECK-ASAN-LINUX: "-export-dynamic"
+// CHECK-ASAN-LINUX-NOT: "-export-dynamic"
+// CHECK-ASAN-LINUX: "--dynamic-list={{.*}}libclang_rt.asan-i386.a.syms"
 
 // RUN: %clangxx -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -target i386-unknown-linux -fsanitize=address \
+// RUN:     -resource-dir=%S/Inputs/empty_resource_dir \
 // RUN:     --sysroot=%S/Inputs/basic_linux_tree \
 // RUN:   | FileCheck --check-prefix=CHECK-ASAN-LINUX-CXX %s
 //
@@ -23,6 +26,7 @@
 // CHECK-ASAN-LINUX-CXX: "-lpthread"
 // CHECK-ASAN-LINUX-CXX: "-ldl"
 // CHECK-ASAN-LINUX-CXX: "-export-dynamic"
+// CHECK-ASAN-LINUX-CXX-NOT: "--dynamic-list"
 // CHECK-ASAN-LINUX-CXX: stdc++
 
 // RUN: %clang -no-canonical-prefixes %s -### -o /dev/null -fsanitize=address \
@@ -58,6 +62,7 @@
 
 // RUN: %clangxx -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -target x86_64-unknown-linux -lstdc++ -fsanitize=thread \
+// RUN:     -resource-dir=%S/Inputs/resource_dir \
 // RUN:     --sysroot=%S/Inputs/basic_linux_tree \
 // RUN:   | FileCheck --check-prefix=CHECK-TSAN-LINUX-CXX %s
 //
@@ -66,11 +71,13 @@
 // CHECK-TSAN-LINUX-CXX: "-whole-archive" "{{.*}}libclang_rt.tsan-x86_64.a" "-no-whole-archive"
 // CHECK-TSAN-LINUX-CXX: "-lpthread"
 // CHECK-TSAN-LINUX-CXX: "-ldl"
-// CHECK-TSAN-LINUX-CXX: "-export-dynamic"
+// CHECK-TSAN-LINUX-CXX-NOT: "-export-dynamic"
+// CHECK-TSAN-LINUX-CXX: "--dynamic-list={{.*}}libclang_rt.tsan-x86_64.a.syms"
 // CHECK-TSAN-LINUX-CXX: stdc++
 
 // RUN: %clangxx -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -target x86_64-unknown-linux -lstdc++ -fsanitize=memory \
+// RUN:     -resource-dir=%S/Inputs/resource_dir \
 // RUN:     --sysroot=%S/Inputs/basic_linux_tree \
 // RUN:   | FileCheck --check-prefix=CHECK-MSAN-LINUX-CXX %s
 //
@@ -79,7 +86,8 @@
 // CHECK-MSAN-LINUX-CXX: "-whole-archive" "{{.*}}libclang_rt.msan-x86_64.a" "-no-whole-archive"
 // CHECK-MSAN-LINUX-CXX: "-lpthread"
 // CHECK-MSAN-LINUX-CXX: "-ldl"
-// CHECK-MSAN-LINUX-CXX: "-export-dynamic"
+// CHECK-MSAN-LINUX-CXX-NOT: "-export-dynamic"
+// CHECK-MSAN-LINUX-CXX: "--dynamic-list={{.*}}libclang_rt.msan-x86_64.a.syms"
 // CHECK-MSAN-LINUX-CXX: stdc++
 
 // RUN: %clang -fsanitize=undefined %s -### -o %t.o 2>&1 \