[Driver] Correctly handle static C++ standard library

When statically linking C++ standard library, we shouldn't add -Bdynamic after including the library on the link line because that might override user settings like -static and -static-pie. Rather, we should surround the library with --push-state/--pop-state to make sure that -Bstatic only applies to C++ standard library and nothing else. This has been supported since GNU ld 2.25 (2014) so backwards compatibility should no longer be a concern. Differential Revision: https://reviews.llvm.org/D110128
dexonsmith · Sep 23, 2021 · 5e28c89 · 5e28c89
1 parent 6cef28e
commit 5e28c89
Show file tree

Hide file tree

Showing 4 changed files with 25 additions and 10 deletions.
diff --git a/clang/lib/Driver/ToolChains/Fuchsia.cpp b/clang/lib/Driver/ToolChains/Fuchsia.cpp
@@ -138,14 +138,13 @@ void fuchsia::Linker::ConstructJob(Compilation &C, const JobAction &JA,
         bool OnlyLibstdcxxStatic = Args.hasArg(options::OPT_static_libstdcxx) &&
                                    !Args.hasArg(options::OPT_static);
         CmdArgs.push_back("--push-state");
-        CmdArgs.push_back("--as-needed");
         if (OnlyLibstdcxxStatic)
           CmdArgs.push_back("-Bstatic");
+        else
+          CmdArgs.push_back("--as-needed");
         ToolChain.AddCXXStdlibLibArgs(Args, CmdArgs);
-        if (OnlyLibstdcxxStatic)
-          CmdArgs.push_back("-Bdynamic");
-        CmdArgs.push_back("-lm");
         CmdArgs.push_back("--pop-state");
+        CmdArgs.push_back("-lm");
       }
     }
 

diff --git a/clang/lib/Driver/ToolChains/Gnu.cpp b/clang/lib/Driver/ToolChains/Gnu.cpp
@@ -577,11 +577,11 @@ void tools::gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     if (ToolChain.ShouldLinkCXXStdlib(Args)) {
       bool OnlyLibstdcxxStatic = Args.hasArg(options::OPT_static_libstdcxx) &&
                                  !Args.hasArg(options::OPT_static);
+      CmdArgs.push_back("--push-state");
       if (OnlyLibstdcxxStatic)
         CmdArgs.push_back("-Bstatic");
       ToolChain.AddCXXStdlibLibArgs(Args, CmdArgs);
-      if (OnlyLibstdcxxStatic)
-        CmdArgs.push_back("-Bdynamic");
+      CmdArgs.push_back("--pop-state");
     }
     CmdArgs.push_back("-lm");
   }

diff --git a/clang/test/Driver/fuchsia.cpp b/clang/test/Driver/fuchsia.cpp
@@ -37,8 +37,8 @@
 // CHECK: "--push-state"
 // CHECK: "--as-needed"
 // CHECK: "-lc++"
-// CHECK: "-lm"
 // CHECK: "--pop-state"
+// CHECK: "-lm"
 // CHECK-X86_64: "[[RESOURCE_DIR]]{{/|\\\\}}lib{{/|\\\\}}x86_64-unknown-fuchsia{{/|\\\\}}libclang_rt.builtins.a"
 // CHECK-AARCH64: "[[RESOURCE_DIR]]{{/|\\\\}}lib{{/|\\\\}}aarch64-unknown-fuchsia{{/|\\\\}}libclang_rt.builtins.a"
 // CHECK-RISCV64: "[[RESOURCE_DIR]]{{/|\\\\}}lib{{/|\\\\}}riscv64-unknown-fuchsia{{/|\\\\}}libclang_rt.builtins.a"
@@ -55,12 +55,10 @@
 // RUN:     -fuse-ld=lld 2>&1 \
 // RUN:     | FileCheck %s -check-prefix=CHECK-STATIC
 // CHECK-STATIC: "--push-state"
-// CHECK-STATIC: "--as-needed"
 // CHECK-STATIC: "-Bstatic"
 // CHECK-STATIC: "-lc++"
-// CHECK-STATIC: "-Bdynamic"
-// CHECK-STATIC: "-lm"
 // CHECK-STATIC: "--pop-state"
+// CHECK-STATIC: "-lm"
 // CHECK-STATIC: "-lc"
 
 // RUN: %clangxx %s -### --target=x86_64-unknown-fuchsia -nostdlib++ -fuse-ld=lld 2>&1 \

diff --git a/clang/test/Driver/linux-ld.c b/clang/test/Driver/linux-ld.c
@@ -496,6 +496,24 @@
 // CHECK-GCC-VERSION1: "{{.*}}ld{{(.exe)?}}" "--sysroot=[[SYSROOT:[^"]+]]"
 // CHECK-GCC-VERSION1: "{{.*}}/Inputs/basic_linux_tree/usr/lib/gcc/i386-unknown-linux/10.2.0{{/|\\\\}}crtbegin.o"
 
+// RUN: %clangxx -x c++ %s -### 2>&1 \
+// RUN:     --target=x86_64-unknown-linux-gnu \
+// RUN:     -stdlib=libc++ \
+// RUN:   | FileCheck --check-prefix=CHECK-BASIC-LIBCXX-SHARED %s
+// CHECK-BASIC-LIBCXX-SHARED: "--push-state"
+// CHECK-BASIC-LIBCXX-SHARED-SAME: {{^}} "-lc++"
+// CHECK-BASIC-LIBCXX-SHARED-SAME: {{^}} "--pop-state"
+// CHECK-BASIC-LIBCXX-SHARED-SAME: {{^}} "-lm"
+// RUN: %clangxx  -x c++ %s -### 2>&1 \
+// RUN:     --target=x86_64-unknown-linux-gnu \
+// RUN:     -stdlib=libc++ -static-libstdc++ \
+// RUN:   | FileCheck --check-prefix=CHECK-BASIC-LIBCXX-STATIC %s
+// CHECK-BASIC-LIBCXX-STATIC: "--push-state"
+// CHECK-BASIC-LIBCXX-STATIC-SAME: {{^}} "-Bstatic"
+// CHECK-BASIC-LIBCXX-STATIC-SAME: {{^}} "-lc++"
+// CHECK-BASIC-LIBCXX-STATIC-SAME: {{^}} "--pop-state"
+// CHECK-BASIC-LIBCXX-STATIC-SAME: {{^}} "-lm"
+
 // Test a simulated installation of libc++ on Linux, both through sysroot and
 // the installation path of Clang.
 // RUN: %clangxx -no-canonical-prefixes -x c++ %s -### -o %t.o 2>&1 \