[PECOFF] Do not write duplicate directives to .def file.

This is a follow-up patch for r220333. r220333 renames exported symbols.
That raised another issue; if we have both decorated and undecorated names
for the same symbol, we'll end up have two duplicate exported symbol
entries.

This is a fix for that issue by removing duplciate entries.

llvm-svn: 220350

lld/lib/ReaderWriter/PECOFF/LinkerGeneratedSymbolFile.h

@@ -12,6 +12,7 @@
 #include "lld/Core/Simple.h"
 #include "lld/ReaderWriter/PECOFFLinkingContext.h"
 #include "llvm/Support/Allocator.h"
+#include <algorithm>
 #include <mutex>
 
 using llvm::COFF::WindowsSubsystem;
@@ -253,15 +254,33 @@ public:
   }
 
   const File *find(StringRef sym, bool dataSymbolOnly) const override {
+    typedef PECOFFLinkingContext::ExportDesc ExportDesc;
     auto it = _exportedSyms.find(sym);
     if (it == _exportedSyms.end())
       return nullptr;
     std::string replace;
     if (!findDecoratedSymbol(_ctx, _syms.get(), sym.str(), replace))
       return nullptr;
-    it->second->name = replace;
-    if (_ctx->deadStrip())
-      _ctx->addDeadStripRoot(_ctx->allocate(replace));
+    ExportDesc *desc = it->second;
+
+    // We found a decorated symbol. There may be another symbol that
+    // has the same decorated name. If that's the case, we remove the
+    // duplicate item.
+    std::vector<ExportDesc> &exp = _ctx->getDllExports();
+    auto isFound = std::find_if(
+        exp.begin(), exp.end(),
+        [&](ExportDesc &e) { return e.getExternalName().equals(replace); });
+    if (isFound != exp.end()) {
+      exp.erase(
+          std::remove_if(exp.begin(), exp.end(),
+                         [&](ExportDesc &e) { return &e == desc; }),
+          exp.end());
+    } else {
+      it->second->name = replace;
+      if (_ctx->deadStrip())
+        _ctx->addDeadStripRoot(_ctx->allocate(replace));
+    }
+
     return new (_alloc) impl::SymbolRenameFile(sym, replace);
   }
 

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

@@ -10,7 +10,7 @@ sections:
   - Name:            .drectve
     Characteristics: [ IMAGE_SCN_LNK_INFO, IMAGE_SCN_LNK_REMOVE ]
     Alignment:       2147483648
-    SectionData:     2f6578706f72743a6578706f7274666e334032353600  # /export:exportfn3@256
+    SectionData:     2f6578706f72743a5f6578706f7274666e334032353600  # /export:_exportfn3@256
 symbols:
   - Name:            .text
     Value:           0
@@ -42,7 +42,7 @@ symbols:
     SimpleType:      IMAGE_SYM_TYPE_NULL
     ComplexType:     IMAGE_SYM_DTYPE_NULL
     StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
-  - Name:            exportfn3@256
+  - Name:            _exportfn3@256
     Value:           16
     SectionNumber:   1
     SimpleType:      IMAGE_SYM_TYPE_NULL

lld/test/pecoff/export.test

@@ -39,8 +39,8 @@ 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  exportfn5
-CHECK4-NEXT:        8   0x2010  exportfn3@256
+CHECK4-NEXT:        7   0x2010  exportfn3@256
+CHECK4-NEXT:        8   0x2010  exportfn5
 
 # RUN: lld -flavor link /out:%t5.dll /dll /entry:init \
 # RUN:   /export:exportfn7 -- %t.obj
@@ -49,7 +49,8 @@ CHECK4-NEXT:        8   0x2010  exportfn3@256
 CHECK5:      Export Table:
 CHECK5:      DLL name: export.test.tmp5.dll
 CHECK5:       Ordinal      RVA  Name
-CHECK5-NEXT:        1   0x2010  exportfn7
+CHECK5-NEXT:        1   0x2010  exportfn3@256
+CHECK5-NEXT:        2   0x2010  exportfn7
 
 # RUN: lld -flavor link /out:%t6.dll /dll /entry:init \
 # RUN:   /export:exportfn8 -- %t.obj
@@ -61,14 +62,16 @@ CHECK6:       Ordinal      RVA  Name
 CHECK6-NEXT:        1   0x2010  ?exportfn8@@YAXXZ
 
 # RUN: lld -flavor link /out:%t6.dll /dll /entry:init \
-# RUN:   /export:exportfn8 /export:exportfn8 -- %t.obj
+# RUN:   /export:exportfn8 /export:exportfn8 /export:exportfn3 -- %t.obj
 # RUN: llvm-objdump -p %t6.dll | FileCheck -check-prefix=DUP %s
 
 DUP:      Export Table:
 DUP:      DLL name: export.test.tmp6.dll
 DUP:       Ordinal      RVA  Name
-DUP:            1   0x2010  ?exportfn8@@YAXXZ
-DUP-NOT:        1   0x2010  ?exportfn8@@YAXXZ
+DUP-NEXT:        1   0x2010  ?exportfn8@@YAXXZ
+DUP-NEXT:        2   0x2010  exportfn3@256
+DUP-NOT:  ?exportfn8@@YAXXZ
+DUP-NOT:  exportfn3@256
 
 # RUN: yaml2obj %p/Inputs/export.obj.yaml > %t.obj
 #