Fix crash with unsupported architectures in Linux/Gnu target triples.

[fhahn]

Summary

This patch adds a check and an error message to gnutools::Linker::ConstructJob in case the architecture is not supported. For most other operating systems, the error message is created in lib/Basic/Targets.cpp:AllocateTarget, but when construction the linker arguments for the gnutools linker a supported architecture is required.

[fhahn]

Ping.

[echristo]

LGTM.

Thanks!

[joerg]

LGTM with a small cleanup.

lib/Driver/Tools.cpp

10018

Please write this as

 if (const char *LDMOption = ...) {
   ...
} else {
   D.Diag(...);
   return;
}

[fhahn]

Addressed @joerg's comment.

lib/Driver/Tools.cpp

case llvm::Triple::mips64el:
     return "elf64ltsmip";
   case llvm::Triple::systemz:
     return "elf64_s390";
   case llvm::Triple::x86_64:
     if (T.getEnvironment() == llvm::Triple::GNUX32)
       return "elf32_x86_64";
     return "elf_x86_64";
   default:
-    llvm_unreachable("Unexpected arch");
+    return nullptr;
   }
 }
 
 void gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
                                     const InputInfo &Output,
                                     const InputInfoList &Inputs,
                                     const ArgList &Args,
                                     const char *LinkingOutput) const {
void gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
 
   for (const auto &Opt : ToolChain.ExtraOpts)
     CmdArgs.push_back(Opt.c_str());
 
   if (!Args.hasArg(options::OPT_static)) {
     CmdArgs.push_back("--eh-frame-hdr");
   }
 
+  const char *LDMOption = getLDMOption(ToolChain.getTriple(), Args);
+  if (!LDMOption) {
+    D.Diag(diag::err_target_unknown_triple) << Triple.str();
+    return;
+  }
   CmdArgs.push_back("-m");
-  CmdArgs.push_back(getLDMOption(ToolChain.getTriple(), Args));
+  CmdArgs.push_back(LDMOption);
 
   if (Args.hasArg(options::OPT_static)) {
     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)) {

test/Driver/unsupported-target-arch.c

+// Tests that clang does not crash with invalid architectures in target triples.
+//
+// RUN: not %clang --target=noarch-unknown-linux -o %t.o %s 2> %t.err
+// RUN: FileCheck --input-file=%t.err --check-prefix=CHECK-NOARCH-LINUX %s
+// CHECK-NOARCH-LINUX: error: unknown target triple 'noarch-unknown-linux', please use -triple or -arch
+//
+// RUN: not %clang --target=noarch-unknown-darwin -o %t.o %s 2> %t.err
+// RUN: FileCheck --input-file=%t.err --check-prefix=CHECK-NOARCH-DARWIN %s
+// CHECK-NOARCH-DARWIN: error: unknown target triple 'unknown-unknown-macosx{{.+}}', please use -triple or -arch
+//
+// RUN: not %clang --target=noarch-unknown-windows -o %t.o %s 2> %t.err
+// RUN: FileCheck --input-file=%t.err --check-prefix=CHECK-NOARCH-WINDOWS %s
+// CHECK-NOARCH-WINDOWS: error: unknown target triple 'noarch-unknown-windows-{{.+}}', please use -triple or -arch
+//
+// RUN: not %clang --target=noarch-unknown-freebsd -o %t.o %s 2> %t.err
+// RUN: FileCheck --input-file=%t.err --check-prefix=CHECK-NOARCH-FREEBSD %s
+// CHECK-NOARCH-FREEBSD: error: unknown target triple 'noarch-unknown-freebsd', please use -triple or -arch
+//
+// RUN: not %clang --target=noarch-unknown-netbsd -o %t.o %s 2> %t.err
+// RUN: FileCheck --input-file=%t.err --check-prefix=CHECK-NOARCH-NETBSD %s
+// CHECK-NOARCH-NETBSD: error: unknown target triple 'noarch-unknown-netbsd', please use -triple or -arch
+//
+// RUN: not %clang --target=noarch-unknown-nacl -o %t.o %s 2> %t.err
+// RUN: FileCheck --input-file=%t.err --check-prefix=CHECK-NOARCH-NACL %s
+// CHECK-NOARCH-NACL:  error: the target architecture 'noarch' is not supported by the target 'Native Client'