[clang] 408e6de - [Driver][Gnu] Support -shared -static: pass -shared to ld and use crtbeginS.o

[Fangrui Song via cfe-commits]

Author: Fangrui Song
Date: 2021-10-19T01:09:41-07:00
New Revision: 408e6de8c09fc7e71329199947e977fe1c40caf1

URL: https://github.com/llvm/llvm-project/commit/408e6de8c09fc7e71329199947e977fe1c40caf1
DIFF: https://github.com/llvm/llvm-project/commit/408e6de8c09fc7e71329199947e977fe1c40caf1.diff

LOG: [Driver][Gnu] Support -shared -static: pass -shared to ld and use crtbeginS.o

This mode never works (mismatching crtbeginT.o and crtendS.o) and probably
unsupported by GCC on glibc based Linux distro (incorrect crtbeginT.o causes
linker error) but makes sense (-shared means building a shared object, -static
means avoid shared object dependencies) and can be used on musl based Linux
distro.

mingw supports this mode as well.

Added: 
    clang/test/Driver/Inputs/basic_linux_tree/usr/lib/gcc/x86_64-unknown-linux/10.2.0/crtbeginS.o
    clang/test/Driver/Inputs/basic_linux_tree/usr/lib/gcc/x86_64-unknown-linux/10.2.0/crtendS.o

Modified: 
    clang/lib/Driver/ToolChains/Gnu.cpp
    clang/test/Driver/linux-ld.c

Removed: 
    


################################################################################
diff  --git a/clang/lib/Driver/ToolChains/Gnu.cpp b/clang/lib/Driver/ToolChains/Gnu.cpp
index fe5bda5c6605e..80e379cb64711 100644
--- a/clang/lib/Driver/ToolChains/Gnu.cpp
+++ b/clang/lib/Driver/ToolChains/Gnu.cpp
@@ -473,17 +473,16 @@ void tools::gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     return;
   }
 
+  if (Args.hasArg(options::OPT_shared))
+    CmdArgs.push_back("-shared");
+
   if (IsStatic) {
     if (Arch == llvm::Triple::arm || Arch == llvm::Triple::armeb ||
         Arch == llvm::Triple::thumb || Arch == llvm::Triple::thumbeb)
       CmdArgs.push_back("-Bstatic");
     else
       CmdArgs.push_back("-static");
-  } else if (Args.hasArg(options::OPT_shared)) {
-    CmdArgs.push_back("-shared");
-  }
-
-  if (!IsStatic) {
+  } else {
     if (Args.hasArg(options::OPT_rdynamic))
       CmdArgs.push_back("-export-dynamic");
 
@@ -534,10 +533,10 @@ void tools::gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
       }
       if (P.empty()) {
         const char *crtbegin;
-        if (IsStatic)
-          crtbegin = isAndroid ? "crtbegin_static.o" : "crtbeginT.o";
-        else if (Args.hasArg(options::OPT_shared))
+        if (Args.hasArg(options::OPT_shared))
           crtbegin = isAndroid ? "crtbegin_so.o" : "crtbeginS.o";
+        else if (IsStatic)
+          crtbegin = isAndroid ? "crtbegin_static.o" : "crtbeginT.o";
         else if (IsPIE || IsStaticPIE)
           crtbegin = isAndroid ? "crtbegin_dynamic.o" : "crtbeginS.o";
         else

diff  --git a/clang/test/Driver/Inputs/basic_linux_tree/usr/lib/gcc/x86_64-unknown-linux/10.2.0/crtbeginS.o b/clang/test/Driver/Inputs/basic_linux_tree/usr/lib/gcc/x86_64-unknown-linux/10.2.0/crtbeginS.o
new file mode 100644
index 0000000000000..e69de29bb2d1d

diff  --git a/clang/test/Driver/Inputs/basic_linux_tree/usr/lib/gcc/x86_64-unknown-linux/10.2.0/crtendS.o b/clang/test/Driver/Inputs/basic_linux_tree/usr/lib/gcc/x86_64-unknown-linux/10.2.0/crtendS.o
new file mode 100644
index 0000000000000..e69de29bb2d1d

diff  --git a/clang/test/Driver/linux-ld.c b/clang/test/Driver/linux-ld.c
index cc505588331bb..102deda5c1c47 100644
--- a/clang/test/Driver/linux-ld.c
+++ b/clang/test/Driver/linux-ld.c
@@ -319,7 +319,13 @@
 // CHECK-LD-64-STATIC: "-L[[SYSROOT]]/lib"
 // CHECK-LD-64-STATIC: "-L[[SYSROOT]]/usr/lib"
 // CHECK-LD-64-STATIC: "--start-group" "-lgcc" "-lgcc_eh" "-lc" "--end-group"
-//
+
+// RUN: %clang -### %s --target=x86_64-unknown-linux -rtlib=platform --unwindlib=platform -shared -static \
+// RUN:   --gcc-toolchain= --sysroot=%S/Inputs/basic_linux_tree 2>&1 | FileCheck --check-prefix=CHECK-LD-SHARED-STATIC %s
+// CHECK-LD-SHARED-STATIC: "-shared" "-static"
+// CHECK-LD-SHARED-STATIC: "{{.*}}/usr/lib/gcc/x86_64-unknown-linux/10.2.0{{/|\\\\}}crtbeginS.o"
+// CHECK-LD-SHARED-STATIC: "{{.*}}/usr/lib/gcc/x86_64-unknown-linux/10.2.0{{/|\\\\}}crtendS.o"
+
 // Check that flags can be combined. The -static dominates.
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     --target=x86_64-unknown-linux -rtlib=platform --unwindlib=platform \