From d31cf6065f4c096cf703ea32f84fa843b44a978b Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@google.com>
Date: Wed, 3 Dec 2014 04:34:20 +0000
Subject: [PATCH] [PECOFF] Fix a bug in /export option handler.

/export option can be given multiple times to specify multiple
symbols to be exported. /export accepts both decorated and
undecorated name.

If you give both undecorated and decorated name of the same symbol
to /export, they are resolved to the same symbol. In this case,
we need to de-duplicate the exported names, so that we don't have
duplicated items in the export symbol table in a DLL.

We remove duplicate items from a vector. The bug was there.
Because we had pointers pointing to elements of the vector,
after an item is removed, they would point wrong elements.

This patch is to remove these pointers. Added a test for that case.

llvm-svn: 223200
---
 lld/lib/ReaderWriter/PECOFF/LinkerGeneratedSymbolFile.h | 17 ++++++++++-------
 lld/test/pecoff/export.test                             |  2 ++
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/lld/lib/ReaderWriter/PECOFF/LinkerGeneratedSymbolFile.h b/lld/lib/ReaderWriter/PECOFF/LinkerGeneratedSymbolFile.h
index 409dd64..4feaec6 100644
--- a/lld/lib/ReaderWriter/PECOFF/LinkerGeneratedSymbolFile.h
+++ b/lld/lib/ReaderWriter/PECOFF/LinkerGeneratedSymbolFile.h
@@ -250,18 +250,16 @@ public:
       : VirtualArchiveLibraryFile("<export>"), _syms(syms),
         _ctx(const_cast<PECOFFLinkingContext *>(&ctx)) {
     for (PECOFFLinkingContext::ExportDesc &desc : _ctx->getDllExports())
-      _exportedSyms[desc.name] = &desc;
+      _exportedSyms.insert(desc.name);
   }
 
   const File *find(StringRef sym, bool dataSymbolOnly) const override {
     typedef PECOFFLinkingContext::ExportDesc ExportDesc;
-    auto it = _exportedSyms.find(sym);
-    if (it == _exportedSyms.end())
+    if (_exportedSyms.count(sym) == 0)
       return nullptr;
     std::string replace;
     if (!findDecoratedSymbol(_ctx, _syms.get(), sym.str(), replace))
       return nullptr;
-    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
@@ -273,10 +271,15 @@ public:
     if (isFound != exp.end()) {
       exp.erase(
           std::remove_if(exp.begin(), exp.end(),
-                         [&](ExportDesc &e) { return &e == desc; }),
+                         [&](ExportDesc &e) { return e.name == sym; }),
           exp.end());
     } else {
-      it->second->name = replace;
+      for (ExportDesc &e : exp) {
+        if (e.name == sym) {
+          e.name = replace;
+          break;
+        }
+      }
       if (_ctx->deadStrip())
         _ctx->addDeadStripRoot(_ctx->allocate(replace));
     }
@@ -285,7 +288,7 @@ public:
   }
 
 private:
-  std::map<std::string, PECOFFLinkingContext::ExportDesc *> _exportedSyms;
+  std::set<std::string> _exportedSyms;
   std::shared_ptr<ResolvableSymbols> _syms;
   mutable llvm::BumpPtrAllocator _alloc;
   mutable PECOFFLinkingContext *_ctx;
diff --git a/lld/test/pecoff/export.test b/lld/test/pecoff/export.test
index cbe8960..dd73c41 100644
--- a/lld/test/pecoff/export.test
+++ b/lld/test/pecoff/export.test
@@ -62,6 +62,7 @@ CHECK6:       Ordinal      RVA  Name
 CHECK6-NEXT:        1   0x2010  ?exportfn8@@YAXXZ
 
 # RUN: lld -flavor link /out:%t6.dll /dll /entry:init \
+# RUN:   /export:exportfn7 /export:exportfn7@8 \
 # RUN:   /export:exportfn8 /export:exportfn8 /export:exportfn3 -- %t.obj
 # RUN: llvm-objdump -p %t6.dll | FileCheck -check-prefix=DUP %s
 
@@ -70,6 +71,7 @@ DUP:      DLL name: export.test.tmp6.dll
 DUP:       Ordinal      RVA  Name
 DUP-NEXT:        1   0x2010  ?exportfn8@@YAXXZ
 DUP-NEXT:        2   0x2010  exportfn3@256
+DUP-NEXT:        3   0x2010  exportfn7@8
 DUP-NOT:  ?exportfn8@@YAXXZ
 DUP-NOT:  exportfn3@256
 
-- 
2.7.4