COFF: Handle /include in .drectve.

We don't want to insert a new symbol to the symbol table while reading
a .drectve section because it's going to be too complicated.
That we are reading a directive section means that we are currently
reading some object file. Adding a new undefined symbol to the symbol
table can trigger a library file to read a new file, so it would make
the call stack too deep.

In this patch, I add new symbol names to a list to resolve them later.

llvm-svn: 240076

lld/COFF/Config.h

@@ -53,6 +53,9 @@ struct Configuration {
   std::set<StringRef> NoDefaultLibs;
   bool NoDefaultLibAll = false;
 
+  // Used for /include.
+  std::set<StringRef> Includes;
+
   // True if we are creating a DLL.
   bool DLL = false;
   StringRef Implib;

lld/COFF/Driver.cpp

@@ -118,6 +118,9 @@ LinkerDriver::parseDirectives(StringRef S,
       if (auto EC = checkFailIfMismatch(Arg->getValue()))
         return EC;
       break;
+    case OPT_incl:
+      Config->Includes.insert(Arg->getValue());
+      break;
     default:
       llvm::errs() << Arg->getSpelling() << " is not allowed in .drectve\n";
       return make_error_code(LLDError::InvalidOption);
@@ -343,6 +346,10 @@ bool LinkerDriver::link(int Argc, const char *Argv[]) {
     if (parseAlternateName(Arg->getValue()))
       return false;
 
+  // Handle /include
+  for (auto *Arg : Args->filtered(OPT_incl))
+    Config->Includes.insert(Arg->getValue());
+
   // Handle /implib
   if (auto *Arg = Args->getLastArg(OPT_implib))
     Config->Implib = Arg->getValue();
@@ -443,11 +450,8 @@ bool LinkerDriver::link(int Argc, const char *Argv[]) {
 
   // Add undefined symbols given via the command line.
   // (/include is equivalent to Unix linker's -u option.)
-  for (auto *Arg : Args->filtered(OPT_incl)) {
-    StringRef Sym = Arg->getValue();
+  for (StringRef Sym : Config->Includes)
     Symtab.addUndefined(Sym);
-    Config->GCRoots.insert(Sym);
-  }
 
   // Windows specific -- Create a resource file containing a manifest file.
   if (Config->Manifest == Configuration::Embed) {
@@ -495,7 +499,6 @@ bool LinkerDriver::link(int Argc, const char *Argv[]) {
   for (size_t I = 0; I < Config->Exports.size(); ++I) {
     StringRef Sym = Config->Exports[I].Name;
     Symtab.addUndefined(Sym);
-    Config->GCRoots.insert(Sym);
   }
 
   // Windows specific -- If entry point name is not given, we need to
@@ -509,7 +512,6 @@ bool LinkerDriver::link(int Argc, const char *Argv[]) {
     }
     Config->EntryName = EntryOrErr.get();
   }
-  Config->GCRoots.insert(Config->EntryName);
 
   // Add weak aliases. Weak aliases is a mechanism to give remaining
   // undefined symbols final chance to be resolved successfully.
@@ -533,6 +535,13 @@ bool LinkerDriver::link(int Argc, const char *Argv[]) {
   if (Symtab.reportRemainingUndefines())
     return false;
 
+  // Initialize a list of GC root.
+  for (StringRef Sym : Config->Includes)
+    Config->GCRoots.insert(Sym);
+  for (Export &E : Config->Exports)
+    Config->GCRoots.insert(E.Name);
+  Config->GCRoots.insert(Config->EntryName);
+
   // Do LTO by compiling bitcode input files to a native COFF file
   // then link that file.
   if (auto EC = Symtab.addCombinedLTOObject()) {

lld/test/COFF/include.test

@@ -10,7 +10,9 @@
 # RUN: FileCheck -check-prefix=CHECK2 %s < %t.log
 
 # CHECK1:     Discarded unused
+# CHECK1-NOT: Discarded used
 # CHECK2-NOT: Discarded unused
+# CHECK2-NOT: Discarded used
 
 ---
 header:
@@ -25,6 +27,14 @@ sections:
     Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
     Alignment:       4
     SectionData:     B82A000000C3
+  - Name:            '.text$mn'
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       4
+    SectionData:     B82A000000C3
+  - Name:            .drectve
+    Characteristics: [ IMAGE_SCN_LNK_INFO, IMAGE_SCN_LNK_REMOVE ]
+    Alignment:       2147483648
+    SectionData:     2f696e636c7564653a7573656400  # /include:used
 symbols:
   - Name:            '.text$mn'
     Value:           0
@@ -58,10 +68,16 @@ symbols:
     SimpleType:      IMAGE_SYM_TYPE_NULL
     ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
     StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
-  - Name:            unused
+  - Name:            used
     Value:           0
     SectionNumber:   2
     SimpleType:      IMAGE_SYM_TYPE_NULL
     ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
     StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            unused
+    Value:           0
+    SectionNumber:   3
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
 ...