[MS Compat] Second try to fix quoting behavior of linker directives

[mkuper]

Summary

Apparently, MSVC behavior is somewhat surprising:
For #pragma comment(linker, ...) it expects the comment string to be quoted, but for #pragma comment(lib, ...) it quotes the library name.

So, these are legal:
#pragma comment(linker, "/DEFAULTLIB:\"foo bar.lib\"")
#pragma comment(lib, "foo bar.lib")
And these get rejected:
#pragma comment(linker, "/DEFAULTLIB:foo bar.lib")
#pragma comment(lib, "\"foo bar.lib\"")

[mkuper]

Accompanying backend patch here:
http://reviews.llvm.org/D7652

[rnk]

lgtm

lib/CodeGen/TargetInfo.cpp

public:
   void getDependentLibraryOption(llvm::StringRef Lib,
                                  llvm::SmallString<24> &Opt) const {
     Opt = "\01";
     Opt += Lib;
   }
 };
 
 static std::string qualifyWindowsLibrary(llvm::StringRef Lib) {
-  // If the argument does not end in .lib, automatically add the suffix. This
-  // matches the behavior of MSVC.
-  std::string ArgStr = Lib;
+  // If the argument does not end in .lib, automatically add the suffix.
+  // If the argument contains a space, enclose it in quotes.
+  // This matches the behavior of MSVC.
+  bool Quote = (Lib.find(" ") != StringRef::npos);
+  std::string ArgStr = Quote ? "\"" : "";
+  ArgStr += Lib;
   if (!Lib.endswith_lower(".lib"))
     ArgStr += ".lib";
+  ArgStr += Quote ? "\"" : "";
   return ArgStr;
 }
 
 class WinX86_32TargetCodeGenInfo : public X86_32TargetCodeGenInfo {
 public:
   WinX86_32TargetCodeGenInfo(CodeGen::CodeGenTypes &CGT,
         bool d, bool p, bool w, unsigned RegParms)
     : X86_32TargetCodeGenInfo(CGT, d, p, w, RegParms) {}

test/CodeGen/pragma-comment.c

 // RUN: %clang_cc1 %s -triple i686-pc-win32 -fms-extensions -emit-llvm -o - | FileCheck %s
 // RUN: %clang_cc1 %s -triple x86_64-pc-win32 -fms-extensions -emit-llvm -o - | FileCheck %s
 // RUN: %clang_cc1 %s -triple i686-pc-linux -fms-extensions -emit-llvm -o - | FileCheck -check-prefix LINUX %s
 // RUN: %clang_cc1 %s -triple x86_64-scei-ps4 -fms-extensions -emit-llvm -o - | FileCheck -check-prefix PS4 %s
 
 #pragma comment(lib, "msvcrt.lib")
 #pragma comment(lib, "kernel32")
 #pragma comment(lib, "USER32.LIB")
+#pragma comment(lib, "with space")
 
 #define BAR "2"
 #pragma comment(linker," /bar=" BAR)
+#pragma comment(linker," /foo=\"foo bar\"")
 
 // CHECK: !llvm.module.flags = !{{{.*}}}
 // CHECK: !{{[0-9]+}} = !{i32 6, !"Linker Options", ![[link_opts:[0-9]+]]}
-// CHECK: ![[link_opts]] = !{![[msvcrt:[0-9]+]], ![[kernel32:[0-9]+]], ![[USER32:[0-9]+]], ![[bar:[0-9]+]]}
+// CHECK: ![[link_opts]] = !{![[msvcrt:[0-9]+]], ![[kernel32:[0-9]+]], ![[USER32:[0-9]+]], ![[space:[0-9]+]], ![[bar:[0-9]+]], ![[foo:[0-9]+]]}
 // CHECK: ![[msvcrt]] = !{!"/DEFAULTLIB:msvcrt.lib"}
 // CHECK: ![[kernel32]] = !{!"/DEFAULTLIB:kernel32.lib"}
 // CHECK: ![[USER32]] = !{!"/DEFAULTLIB:USER32.LIB"}
+// CHECK: ![[space]] = !{!"/DEFAULTLIB:\22with space.lib\22"}
 // CHECK: ![[bar]] = !{!" /bar=2"}
+// CHECK: ![[foo]] = !{!" /foo=\22foo bar\22"}
 
 // LINUX: !{!"-lmsvcrt.lib"}
 // LINUX: !{!"-lkernel32"}
 // LINUX: !{!"-lUSER32.LIB"}
 // LINUX: !{!" /bar=2"}
 
 // PS4: !{!"\01msvcrt.lib"}
 // PS4: !{!"\01kernel32"}
 // PS4: !{!"\01USER32.LIB"}
 // PS4: !{!" /bar=2"}