[PECOFF] Drop stdcall's atsign suffix only.

You can omit @number suffix when specifying /export option,
but you can do that only for stdcall functions.

llvm-svn: 207809

lld/lib/ReaderWriter/PECOFF/EdataPass.cpp

@@ -46,7 +46,9 @@ static void assignOrdinals(PECOFFLinkingContext &ctx) {
   ctx.getDllExports().swap(exports);
 }
 
-static StringRef removeAtSignSuffix(StringRef sym) {
+static StringRef removeStdcallSuffix(StringRef sym) {
+  if (!sym.startswith("_"))
+    return sym;
   StringRef trimmed = sym.rtrim("0123456789");
   if (sym.size() != trimmed.size() && trimmed.endswith("@"))
     return trimmed.drop_back();
@@ -63,7 +65,7 @@ static bool getExportedAtoms(PECOFFLinkingContext &ctx, MutableFile *file,
                              std::vector<TableEntry> &ret) {
   std::map<StringRef, const DefinedAtom *> definedAtoms;
   for (const DefinedAtom *atom : file->defined())
-    definedAtoms[removeAtSignSuffix(atom->name())] = atom;
+    definedAtoms[removeStdcallSuffix(atom->name())] = atom;
 
   std::set<PECOFFLinkingContext::ExportDesc> exports;
   for (PECOFFLinkingContext::ExportDesc desc : ctx.getDllExports()) {

lld/test/pecoff/Inputs/export.obj.yaml

@@ -7,6 +7,10 @@ sections:
     Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
     Alignment:       4
     SectionData:     B800000000506800000000680000000050E80000000050E800000000
+  - Name:            .drectve
+    Characteristics: [ IMAGE_SCN_LNK_INFO, IMAGE_SCN_LNK_REMOVE ]
+    Alignment:       2147483648
+    SectionData:     2f6578706f72743a6578706f7274666e334032353600  # /export:exportfn3@256
 symbols:
   - Name:            .text
     Value:           0
@@ -38,4 +42,10 @@ symbols:
     SimpleType:      IMAGE_SYM_TYPE_NULL
     ComplexType:     IMAGE_SYM_DTYPE_NULL
     StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            exportfn3@256
+    Value:           16
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
 ...

lld/test/pecoff/export.test

@@ -39,3 +39,4 @@ CHECK4:      DLL name: export.test.tmp4.dll
 CHECK4:       Ordinal      RVA  Name
 CHECK4-NEXT:        5   0x2008  exportfn1
 CHECK4-NEXT:        6   0x2010  exportfn2
+CHECK4-NEXT:        7   0x2010  exportfn3@256