[Driver] Support ubsan-minimal on Darwin

[vsk]

Summary

Make it possible to use the minimal ubsan runtime on Darwin.

cfe/trunk/lib/Driver/ToolChains/Darwin.cpp

void DarwinClang::AddLinkRuntimeLibArgs(const ArgList &Args,
   }
 
   const SanitizerArgs &Sanitize = getSanitizerArgs();
   if (Sanitize.needsAsanRt())
     AddLinkSanitizerLibArgs(Args, CmdArgs, "asan");
   if (Sanitize.needsLsanRt())
     AddLinkSanitizerLibArgs(Args, CmdArgs, "lsan");
   if (Sanitize.needsUbsanRt())
-    AddLinkSanitizerLibArgs(Args, CmdArgs, "ubsan");
+    AddLinkSanitizerLibArgs(Args, CmdArgs,
+                            Sanitize.requiresMinimalRuntime() ? "ubsan_minimal"
+                                                              : "ubsan");
   if (Sanitize.needsTsanRt())
     AddLinkSanitizerLibArgs(Args, CmdArgs, "tsan");
   if (Sanitize.needsFuzzer() && !Args.hasArg(options::OPT_dynamiclib)) {
     AddLinkSanitizerLibArgs(Args, CmdArgs, "fuzzer", /*shared=*/false);
 
     // Libfuzzer is written in C++ and requires libcxx.
     AddCXXStdlibLibArgs(Args, CmdArgs);
   }

cfe/trunk/test/Driver/sanitizer-ld.c

 // RUN: %clang -fsanitize=undefined -fsanitize-minimal-runtime %s -### -o %t.o 2>&1 \
 // RUN:     -target i386-unknown-linux -fuse-ld=ld \
 // RUN:     --sysroot=%S/Inputs/basic_linux_tree \
 // RUN:   | FileCheck --check-prefix=CHECK-UBSAN-MINIMAL-LINUX %s
 // CHECK-UBSAN-MINIMAL-LINUX: "{{.*}}ld{{(.exe)?}}"
 // CHECK-UBSAN-MINIMAL-LINUX: "-whole-archive" "{{.*}}libclang_rt.ubsan_minimal-i386.a" "-no-whole-archive"
 // CHECK-UBSAN-MINIMAL-LINUX: "-lpthread"
 
+// RUN: %clang -fsanitize=undefined -fsanitize-minimal-runtime %s -### -o %t.o 2>&1 \
+// RUN:     -target x86_64-apple-darwin -fuse-ld=ld \
+// RUN:     --sysroot=%S/Inputs/basic_linux_tree \
+// RUN:   | FileCheck --check-prefix=CHECK-UBSAN-MINIMAL-DARWIN %s
+// CHECK-UBSAN-MINIMAL-DARWIN: "{{.*}}ld{{(.exe)?}}"
+// CHECK-UBSAN-MINIMAL-DARWIN: "{{.*}}libclang_rt.ubsan_minimal_osx_dynamic.dylib"
+
 // RUN: %clang -fsanitize=address,undefined %s -### -o %t.o 2>&1 \
 // RUN:     -target i386-unknown-linux -fuse-ld=ld \
 // RUN:     --sysroot=%S/Inputs/basic_linux_tree \
 // RUN:   | FileCheck --check-prefix=CHECK-ASAN-UBSAN-LINUX %s
 // CHECK-ASAN-UBSAN-LINUX: "{{.*}}ld{{(.exe)?}}"
 // CHECK-ASAN-UBSAN-LINUX: "-whole-archive" "{{.*}}libclang_rt.asan-i386.a" "-no-whole-archive"
 // CHECK-ASAN-UBSAN-LINUX-NOT: libclang_rt.ubsan
 // CHECK-ASAN-UBSAN-LINUX-NOT: "-lstdc++"