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

7 files changed, 127 insertions, 7 deletions

diff --git a/lld/COFF/Config.h b/lld/COFF/Config.h
index 31534aeb397..fafd3bcde2e 100644
--- a/lld/COFF/Config.h
+++ b/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.
diff --git a/lld/COFF/DriverUtils.cpp b/lld/COFF/DriverUtils.cpp
index 2c9ba797f73..736e8463dd8 100644
--- a/lld/COFF/DriverUtils.cpp
+++ b/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;
diff --git a/lld/COFF/Librarian.cpp b/lld/COFF/Librarian.cpp
index 3ce72822180..91316ee6b0c 100644
--- a/lld/COFF/Librarian.cpp
+++ b/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,
-                                                  bool isData) {
+                                                  ImportType ImportType,
+                                                  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;
+  Imp->TypeInfo = (NameType << 2) | ImportType;
 
   // 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 =
diff --git a/lld/COFF/ModuleDef.cpp b/lld/COFF/ModuleDef.cpp
index c9a40ac5ab8..740ce867a7c 100644
--- a/lld/COFF/ModuleDef.cpp
+++ b/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;
diff --git a/lld/test/COFF/Inputs/constant-export.ll b/lld/test/COFF/Inputs/constant-export.ll
new file mode 100644
index 00000000000..2b57e8d083f
--- /dev/null
+++ b/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"}
diff --git a/lld/test/COFF/constant-export.test b/lld/test/COFF/constant-export.test
new file mode 100644
index 00000000000..18b1f5e30d2
--- /dev/null
+++ b/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
+
diff --git a/lld/test/COFF/constant-export.yaml b/lld/test/COFF/constant-export.yaml
new file mode 100644
index 00000000000..7e44bb70c9d
--- /dev/null
+++ b/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
+...