Add EXPERIMENTAL --rtlib=compiler-rt to GNU Clang

This commit is not strictly correct nor accounts for all uses (shared
objects, for example), but it allows one to test the compiler-rt library
on GNU targets.

Using this patch to run the test-suite has already shown me problems
on ARM. Since this is a Darwin-only flag, nobody is using it, so it
shouldn't be a problem.

I will need extension to deal with the shared cases, but since we're
not compiling libclang_rt.so, that's not yet applicable. Many other
problems will have to be fixed first in compiler-rt (such as removing
the 'arch' name from it and making it trully multi-arch, moving it to
the default lib directory, make both .a and .so variants, etc).

llvm-svn: 201307

clang/lib/Driver/Tools.cpp

@@ -1737,6 +1737,24 @@ static StringRef getArchNameForCompilerRTLib(const ToolChain &TC) {
     return TC.getArchName();
 }
 
+// This adds the static libclang_rt.arch.a directly to the command line
+// FIXME: Make sure we can also emit shared objects if they're requested
+// and available, check for possible errors, etc.
+static void addClangRTLinux(
+    const ToolChain &TC, const ArgList &Args, ArgStringList &CmdArgs) {
+  // The runtime is located in the Linux library directory and has name
+  // "libclang_rt.<ArchName>.a".
+  SmallString<128> LibProfile(TC.getDriver().ResourceDir);
+  llvm::sys::path::append(
+      LibProfile, "lib", "linux",
+      Twine("libclang_rt.") + getArchNameForCompilerRTLib(TC) + ".a");
+
+  CmdArgs.push_back(Args.MakeArgString(LibProfile));
+  CmdArgs.push_back("-lgcc_s");
+  if (TC.getDriver().CCCIsCXX())
+    CmdArgs.push_back("-lgcc_eh");
+}
+
 static void addProfileRTLinux(
     const ToolChain &TC, const ArgList &Args, ArgStringList &CmdArgs) {
   if (!(Args.hasArg(options::OPT_fprofile_arcs) ||
@@ -6534,6 +6552,23 @@ static StringRef getLinuxDynamicLinker(const ArgList &Args,
     return "/lib64/ld-linux-x86-64.so.2";
 }
 
+static void AddRunTimeLibs(const ToolChain &TC, const Driver &D,
+                      ArgStringList &CmdArgs, const ArgList &Args) {
+  // Make use of compiler-rt if --rtlib option is used
+  ToolChain::RuntimeLibType RLT = TC.GetRuntimeLibType(Args);
+
+  switch(RLT) {
+  case ToolChain::RLT_CompilerRT:
+    addClangRTLinux(TC, Args, CmdArgs);
+    break;
+  case ToolChain::RLT_Libgcc:
+    AddLibgcc(TC.getTriple(), D, CmdArgs, Args);
+    break;
+  default:
+    llvm_unreachable("Unknown RT-Lib type");
+  }
+}
+
 void gnutools::Link::ConstructJob(Compilation &C, const JobAction &JA,
                                   const InputInfo &Output,
                                   const InputInfoList &Inputs,
@@ -6737,7 +6772,7 @@ void gnutools::Link::ConstructJob(Compilation &C, const JobAction &JA,
         CmdArgs.push_back("-lrt");
       }
 
-      AddLibgcc(ToolChain.getTriple(), D, CmdArgs, Args);
+      AddRunTimeLibs(ToolChain, D, CmdArgs, Args);
 
       if (Args.hasArg(options::OPT_pthread) ||
           Args.hasArg(options::OPT_pthreads) || OpenMP)
@@ -6748,7 +6783,7 @@ void gnutools::Link::ConstructJob(Compilation &C, const JobAction &JA,
       if (Args.hasArg(options::OPT_static))
         CmdArgs.push_back("--end-group");
       else
-        AddLibgcc(ToolChain.getTriple(), D, CmdArgs, Args);
+        AddRunTimeLibs(ToolChain, D, CmdArgs, Args);
     }
 
     if (!Args.hasArg(options::OPT_nostartfiles)) {

clang/test/Driver/linux-ld.c

@@ -35,6 +35,46 @@
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     --target=x86_64-unknown-linux \
+// RUN:     --sysroot=%S/Inputs/basic_linux_tree \
+// RUN:     --rtlib=compiler-rt \
+// RUN:   | FileCheck --check-prefix=CHECK-LD-RT %s
+// CHECK-LD-RT-NOT: warning:
+// CHECK-LD-RT: "{{.*}}ld{{(.exe)?}}" "--sysroot=[[SYSROOT:[^"]+]]"
+// CHECK-LD-RT: "--eh-frame-hdr"
+// CHECK-LD-RT: "-m" "elf_x86_64"
+// CHECK-LD-RT: "-dynamic-linker"
+// CHECK-LD-RT: "{{.*}}/usr/lib/gcc/x86_64-unknown-linux/4.6.0{{/|\\\\}}crtbegin.o"
+// CHECK-LD-RT: "-L[[SYSROOT]]/usr/lib/gcc/x86_64-unknown-linux/4.6.0"
+// CHECK-LD-RT: "-L[[SYSROOT]]/usr/lib/gcc/x86_64-unknown-linux/4.6.0/../../../../x86_64-unknown-linux/lib"
+// CHECK-LD-RT: "-L[[SYSROOT]]/usr/lib/gcc/x86_64-unknown-linux/4.6.0/../../.."
+// CHECK-LD-RT: "-L[[SYSROOT]]/lib"
+// CHECK-LD-RT: "-L[[SYSROOT]]/usr/lib"
+// CHECK-LD-RT: libclang_rt.x86_64.a" "-lgcc_s"
+// CHECK-LD-RT: "-lc"
+// CHECK-LD-RT: libclang_rt.x86_64.a" "-lgcc_s"
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN:     --target=x86_64-unknown-linux \
+// RUN:     --sysroot=%S/Inputs/basic_linux_tree \
+// RUN:     --rtlib=libgcc \
+// RUN:   | FileCheck --check-prefix=CHECK-LD-GCC %s
+// CHECK-LD-GCC-NOT: warning:
+// CHECK-LD-GCC: "{{.*}}ld{{(.exe)?}}" "--sysroot=[[SYSROOT:[^"]+]]"
+// CHECK-LD-GCC: "--eh-frame-hdr"
+// CHECK-LD-GCC: "-m" "elf_x86_64"
+// CHECK-LD-GCC: "-dynamic-linker"
+// CHECK-LD-GCC: "{{.*}}/usr/lib/gcc/x86_64-unknown-linux/4.6.0{{/|\\\\}}crtbegin.o"
+// CHECK-LD-GCC: "-L[[SYSROOT]]/usr/lib/gcc/x86_64-unknown-linux/4.6.0"
+// CHECK-LD-GCC: "-L[[SYSROOT]]/usr/lib/gcc/x86_64-unknown-linux/4.6.0/../../../../x86_64-unknown-linux/lib"
+// CHECK-LD-GCC: "-L[[SYSROOT]]/usr/lib/gcc/x86_64-unknown-linux/4.6.0/../../.."
+// CHECK-LD-GCC: "-L[[SYSROOT]]/lib"
+// CHECK-LD-GCC: "-L[[SYSROOT]]/usr/lib"
+// CHECK-LD-GCC "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed"
+// CHECK-LD-GCC: "-lc"
+// CHECK-LD-GCC: "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed"
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN:     --target=x86_64-unknown-linux \
 // RUN:     -static-libgcc \
 // RUN:     --sysroot=%S/Inputs/basic_linux_tree \
 // RUN:   | FileCheck --check-prefix=CHECK-LD-64-STATIC-LIBGCC %s