[LLD][COFF] Case insensitive compares for /nodefaultlib

[aganea]

Summary

MSVC stamps uppercase strings in directive sections, thus /nodefaultlib must be handled with case insensitive tests.

[aganea]

Updated test.

[rnk]

I guess /nodefaultlib just isn't that common compared to /defaultlib, so this hadn't been reported yet. Fix makes sense to me.

COFF/Driver.cpp

303

I don't think we want this ifdef, I think we want LLD to do this when cross-linking from Linux to Windows. This is something we try to support for Chromium:
https://chromium.googlesource.com/chromium/src/+/master/docs/win_cross.md

[aganea]

Case-insensitive on Linux as requested.

[rnk]

lgtm

[ruiu]

LGTM

COFF/Config.h

struct Configuration {
   llvm::SmallString<128> PDBAltPath;
   llvm::SmallString<128> PDBPath;
   llvm::SmallString<128> PDBSourcePath;
   std::vector<llvm::StringRef> Argv;
 
   // Symbols in this set are considered as live by the garbage collector.
   std::vector<Symbol *> GCRoot;
 
-  std::set<StringRef> NoDefaultLibs;
+  std::set<std::string> NoDefaultLibs;
   bool NoDefaultLibAll = false;
 
   // True if we are creating a DLL.
   bool DLL = false;
   StringRef Implib;
   std::vector<Export> Exports;
   std::set<std::string> DelayLoads;
   std::map<std::string, int> DLLOrder;

COFF/Driver.cpp

static bool isDecorated(StringRef Sym) {
   return Sym.startswith("@") || Sym.contains("@@") || Sym.startswith("?") ||
          (!Config->MinGW && Sym.contains('@'));
 }
 
 // Parses .drectve section contents and returns a list of files
 // specified by /defaultlib.
 void LinkerDriver::parseDirectives(InputFile *File) {
   StringRef S = File->getDirectives();
   if (S.empty())
     return;
 
   log("Directives: " + toString(File) + ": " + S);
 
   ArgParser Parser;
   // .drectve is always tokenized using Windows shell rules.
   // /EXPORT: option can appear too many times, processing in fastpath.
   opt::InputArgList Args;
case OPT_failifmismatch:
       break;
     case OPT_incl:
       addUndefined(Arg->getValue());
       break;
     case OPT_merge:
       parseMerge(Arg->getValue());
       break;
     case OPT_nodefaultlib:
-      Config->NoDefaultLibs.insert(doFindLib(Arg->getValue()));
+      Config->NoDefaultLibs.insert(doFindLib(Arg->getValue()).lower());
       break;
     case OPT_section:
       parseSection(Arg->getValue());
       break;
     case OPT_subsystem:
       parseSubsystem(Arg->getValue(), &Config->Subsystem,
                      &Config->MajorOSVersion, &Config->MinorOSVersion);
       break;

 // it returns None).
 Optional<StringRef> LinkerDriver::findLib(StringRef Filename) {
   if (Config->NoDefaultLibAll)
     return None;
   if (!VisitedLibs.insert(Filename.lower()).second)
     return None;
 
   StringRef Path = doFindLib(Filename);
-  if (Config->NoDefaultLibs.count(Path))
+  if (Config->NoDefaultLibs.count(Path.lower()))
     return None;
 
   if (Optional<sys::fs::UniqueID> ID = getUniqueID(Path))
     if (!VisitedFiles.insert(*ID).second)
       return None;
   return Path;
 }
 
void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
   if (auto *Arg = Args.getLastArg(OPT_machine)) {
     Config->Machine = getMachineType(Arg->getValue());
     if (Config->Machine == IMAGE_FILE_MACHINE_UNKNOWN)
       fatal(Twine("unknown /machine argument: ") + Arg->getValue());
   }
 
   // Handle /nodefaultlib:<filename>
   for (auto *Arg : Args.filtered(OPT_nodefaultlib))
-    Config->NoDefaultLibs.insert(doFindLib(Arg->getValue()));
+    Config->NoDefaultLibs.insert(doFindLib(Arg->getValue()).lower());
 
   // Handle /nodefaultlib
   if (Args.hasArg(OPT_nodefaultlib_all))
     Config->NoDefaultLibAll = true;
 
   // Handle /base
   if (auto *Arg = Args.getLastArg(OPT_base))
     parseNumbers(Arg->getValue(), &Config->ImageBase);

test/COFF/nodefaultlib.test

 CHECK3: error: undefined symbol: MessageBoxA
 CHECK3-NEXT: >>> referenced by {{.*}}hello64.obj:(main)
 
 # RUN: lld-link /libpath:%T /out:%t.exe /entry:main \
 # RUN:   /subsystem:console hello64.obj /defaultlib:std64.lib
 
 # RUN: env LIB=%T lld-link /out:%t.exe /entry:main \
 # RUN:   /subsystem:console hello64.obj /defaultlib:std64.lib
+
+MSVC stamps uppercase references in OBJ directives, thus ensure that passing lowercase 'libcmt' and 'oldnames' to /nodefaultlib works.
+# RUN: lld-link %S/Inputs/precomp.obj %S/Inputs/precomp-a.obj %S/Inputs/precomp-b.obj /nodefaultlib:libcmt /nodefaultlib:oldnames /entry:main /debug /pdb:%t.pdb /out:%t.exe /opt:ref /opt:icf
+# RUN: llvm-pdbutil dump -modules %t.pdb | FileCheck %s -check-prefix UPPERCASE
+
+UPPERCASE-NOT: OLDNAMES
+UPPERCASE-NOT: LIBCMT