[LLD] [COFF] Skip exporting artificial symbols when exporting all symbols

[rnk]

lgtm

COFF/MinGW.cpp

bool AutoExporter::shouldExport(Defined *Sym) const {
   // Only allow the symbol kinds that make sense to export; in particular,
   // disallow import symbols.
   if (!isa<DefinedRegular>(Sym) && !isa<DefinedCommon>(Sym))
     return false;
   if (ExcludeSymbols.count(Sym->getName()))
     return false;
 
   // Don't export anything that looks like an import symbol (which also can be
-  // a manually defined data symbol with such a name).
-  if (Sym->getName().startswith("__imp_"))
+  // a manually defined data symbol with such a name); don't export artificial
+  // symbols like .refptr pointer stubs.
+  if (Sym->getName().startswith("__imp_") || Sym->getName().startswith("."))
     return false;
 
   // If a corresponding __imp_ symbol exists and is defined, don't export it.
   if (Symtab->find(("__imp_" + Sym->getName()).str()))
     return false;
 
   // Check that file is non-null before dereferencing it, symbols not
   // originating in regular object files probably shouldn't be exported.

test/COFF/export-all.s

 # IMPLIB: Symbol: __imp__foobar
 # IMPLIB: Symbol: _foobar
 
 .global _foobar
 .global _DllMainCRTStartup@12
 .global _dataSym
 .global _unexported
 .global __imp__unexported
+.global .refptr._foobar
 .text
 _DllMainCRTStartup@12:
   ret
 _foobar:
   ret
 _unexported:
   ret
 .data
 _dataSym:
   .int 4
 __imp__unexported:
   .int _unexported
+.refptr._foobar:
+  .int _foobar
 
 # Test specifying -export-all-symbols, on an object file that contains
 # dllexport directive for some of the symbols.
 
 # RUN: yaml2obj < %p/Inputs/export.yaml > %t.obj
 #
 # RUN: lld-link -out:%t.dll -dll %t.obj -lldmingw -export-all-symbols -output-def:%t.def
 # RUN: llvm-readobj -coff-exports %t.dll | FileCheck -check-prefix=CHECK2 %s