COFF: add support for CONSTANT exports

The CONSTANT export type is marked as obsolete, but link still supports
this.  Furthermore, WinObjC uses this for certain exports.  Add support
for this export type.

llvm-svn: 301013

lld/COFF/Config.h

@@ -43,6 +43,7 @@ struct Export {
   bool Noname = false;
   bool Data = false;
   bool Private = false;
+  bool Constant = false;
 
   // If an export is a form of /export:foo=dllname.bar, that means
   // that foo should be exported as an alias to bar in the DLL.

lld/COFF/DriverUtils.cpp

@@ -479,6 +479,10 @@ Export parseExport(StringRef Arg) {
       E.Data = true;
       continue;
     }
+    if (Tok.equals_lower("constant")) {
+      E.Constant = true;
+      continue;
+    }
     if (Tok.equals_lower("private")) {
       E.Private = true;
       continue;

lld/COFF/Librarian.cpp

@@ -162,7 +162,7 @@ public:
   // Create a short import file which is described in PE/COFF spec 7. Import
   // Library Format.
   NewArchiveMember createShortImport(StringRef Sym, uint16_t Ordinal,
-                                     ImportNameType NameType, bool isData);
+                                     ImportType Type, ImportNameType NameType);
 };
 }
 
@@ -440,8 +440,8 @@ NewArchiveMember ObjectFactory::createNullThunk(std::vector<uint8_t> &Buffer) {
 
 NewArchiveMember ObjectFactory::createShortImport(StringRef Sym,
                                                   uint16_t Ordinal,
-                                                  ImportNameType NameType,
+                                                  ImportType ImportType,
-                                                  bool isData) {
+                                                  ImportNameType NameType) {
   size_t ImpSize = DLLName.size() + Sym.size() + 2; // +2 for NULs
   size_t Size = sizeof(coff_import_header) + ImpSize;
   char *Buf = Alloc.Allocate<char>(Size);
@@ -456,8 +456,7 @@ NewArchiveMember ObjectFactory::createShortImport(StringRef Sym,
   Imp->SizeOfData = ImpSize;
   if (Ordinal > 0)
     Imp->OrdinalHint = Ordinal;
-  Imp->TypeInfo = (isData ? IMPORT_DATA : IMPORT_CODE);
+  Imp->TypeInfo = (NameType << 2) | ImportType;
-  Imp->TypeInfo |= NameType << 2;
 
   // Write symbol name and DLL name.
   memcpy(P, Sym.data(), Sym.size());
@@ -490,11 +489,18 @@ void lld::coff::writeImportLibrary() {
     if (E.Private)
       continue;
 
-    ImportNameType Type = getNameType(E.SymbolName, E.Name);
+    ImportType ImportType = IMPORT_CODE;
+    if (E.Data)
+      ImportType = IMPORT_DATA;
+    if (E.Constant)
+      ImportType = IMPORT_CONST;
+
+    ImportNameType NameType = getNameType(E.SymbolName, E.Name);
     std::string Name = E.ExtName.empty()
                            ? std::string(E.SymbolName)
                            : replace(E.SymbolName, E.Name, E.ExtName);
-    Members.push_back(OF.createShortImport(Name, E.Ordinal, Type, E.Data));
+    Members.push_back(OF.createShortImport(Name, E.Ordinal, ImportType,
+                                           NameType));
   }
 
   std::pair<StringRef, std::error_code> Result =

lld/COFF/ModuleDef.cpp

@@ -38,6 +38,7 @@ enum Kind {
   Comma,
   Equal,
   KwBase,
+  KwConstant,
   KwData,
   KwExports,
   KwHeapsize,
@@ -92,6 +93,7 @@ public:
       StringRef Word = Buf.substr(0, End);
       Kind K = llvm::StringSwitch<Kind>(Word)
                    .Case("BASE", KwBase)
+                   .Case("CONSTANT", KwConstant)
                    .Case("DATA", KwData)
                    .Case("EXPORTS", KwExports)
                    .Case("HEAPSIZE", KwHeapsize)
@@ -227,6 +229,11 @@ private:
         E.Data = true;
         continue;
       }
+      if (Tok.K == KwConstant) {
+        warn("CONSTANT keyword is obsolete; use DATA");
+        E.Constant = true;
+        continue;
+      }
       if (Tok.K == KwPrivate) {
         E.Private = true;
         continue;

lld/test/COFF/Inputs/constant-export.ll

@@ -0,0 +1,10 @@
+target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
+target triple = "i686-unknown-windows-msvc18.0.0"
+
+@__CFConstantStringClassReference = common global [32 x i32] zeroinitializer, align 4
+
+!llvm.module.flags = !{!0}
+
+!0 = !{i32 6, !"Linker Options", !1}
+!1 = !{!2}
+!2 = !{!" -export:___CFConstantStringClassReference,CONSTANT"}

lld/test/COFF/constant-export.test

@@ -0,0 +1,9 @@
+# RUN: mkdir -p %t
+# RUN: yaml2obj -o %t/constant-export.obj %S/constant-export.yaml
+# RUN: lld-link /machine:x86 /dll /entry:__CFConstantStringClassReference -out:%t/constant-export.dll %t/constant-export.obj
+# RUN: llvm-readobj -coff-exports %t/constant-export.lib | FileCheck %s
+
+# CHECK: Type: const
+# CHECK: Name type: noprefix
+# CHECK: Symbol: __imp____CFConstantStringClassReference
+

lld/test/COFF/constant-export.yaml

@@ -0,0 +1,83 @@
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_I386
+  Characteristics: [  ]
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       4
+    SectionData:     ''
+  - Name:            .data
+    Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_MEM_READ, IMAGE_SCN_MEM_WRITE ]
+    Alignment:       4
+    SectionData:     ''
+  - Name:            .bss
+    Characteristics: [ IMAGE_SCN_CNT_UNINITIALIZED_DATA, IMAGE_SCN_MEM_READ, IMAGE_SCN_MEM_WRITE ]
+    Alignment:       4
+    SectionData:     ''
+  - Name:            .drectve
+    Characteristics: [ IMAGE_SCN_LNK_INFO, IMAGE_SCN_LNK_REMOVE ]
+    Alignment:       1
+    SectionData:     20202D6578706F72743A5F5F5F4346436F6E7374616E74537472696E67436C6173735265666572656E63652C434F4E5354414E54
+symbols:
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          0
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        0
+      Number:          1
+  - Name:            .data
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          0
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        0
+      Number:          2
+  - Name:            .bss
+    Value:           0
+    SectionNumber:   3
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          0
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        0
+      Number:          3
+  - Name:            .drectve
+    Value:           0
+    SectionNumber:   4
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          52
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        1983959296
+      Number:          4
+  - Name:            '@feat.00'
+    Value:           1
+    SectionNumber:   -1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+  - Name:            ___CFConstantStringClassReference
+    Value:           128
+    SectionNumber:   0
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...